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authorXin LI <delphij@FreeBSD.org>2020-01-03 00:31:48 +0000
committerXin LI <delphij@FreeBSD.org>2020-01-03 00:31:48 +0000
commit9708ba9f29bd83e21d532f89f93b8c3bf945e843 (patch)
tree70fc505629589f9d42164d41b6dd23ba662748d1
parentf6afed726b00d16cf7a63f9285efb13d99a88da8 (diff)
downloadsrc-9708ba9f29bd83e21d532f89f93b8c3bf945e843.tar.gz
src-9708ba9f29bd83e21d532f89f93b8c3bf945e843.zip
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy. This utility was initially written for FAT12/16, which were inherently small. When FAT32 support was added, the old data structure and algorithms remain used with minimal changes. With growing size of FAT32 media, the current data structure that requires 4 32-bit variables per each FAT32 table entry would consume up to 4 GiB of RAM, which can be too big for systems with limited RAM available. Address this by taking a different approach of validating the FAT. The FAT is essentially a set of linked lists of chains that was referenced by directory entries, and the checker needs to make sure that the linked chains of clusters do not have cross-linked chains, and every chain were referenced by one and only one directory entry. Instead of keeping track of the chain's 'head' cluster number, the size of the chain, the used status of the chain and the "next" pointer which is content of the FAT table, we create accessors for the FAT table data for the "next" pointer, and keep only one bit to indicate if the current cluster is a 'head' node of a cluster chain, in a bitmap. We further overhaul the FAT checker to find out the possible head nodes by excluding ones that are not (in other words, nodes that have some other nodes claiming them as the next node) instead of marking the head nodes for each node on the chain. This approach greatly reduced the complexiety of computation from O(N^2) worst case, to an O(N) scan for worst case. The file (cluster chain) length is not useful for the FAT checker, so don't bother to calculate them in the FAT checker and instead leave the task to the directory structure check, at which point we would have non-crossed cluster chains, and we are guaranteed that each cluster will be visited for at most one time. When checking the directory structures, we use the head node indicator to as the visited (used) flag: every cluster chain can only be referenced by one directory entry, so we clear them when calculating the length of the chain, and we can immediately tell if there are anomalies in the directory entry. As a result, the required RAM size is now 1 bit per each entry of the FAT table, plus memory needed to hold the FAT table in memory, instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16, we will load the whole FAT table into memory as they are smaller than 128KiB, and for FAT32, we first attempt to mmap() it into memory, and when that fails, we would fall back to a simple LRU cache of 4 MiB of RAM. sbin/fsck_msdosfs/boot.c: - Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster number. - FAT32: check if root directory starts with a valid cluster number, moved from dir.c. There is no point to proceed if the filesystem is already damaged beyond repair. sbin/fsck_msdosfs/check.c: - Combine phase 1 and phase 2, now that the readfat() is able to detect cross chains. sbin/fsck_msdosfs/dir.c: - Refactor code to use FAT accessor instead of accessing the internal representation of FAT table. - Make use of the cluster chain head bitmap. - Clarify and simplify directory entry check, remove unnecessary checks that are would be done at a later time (for example, whether the directory's second cluster is a valid one, which is examined more throughly in a later checkchain() and does not prevent us from proceeding further). sbin/fsck_msdosfs/dosfs.h: - Remove internal representation of FAT table, which is replaced by the head bitmap that is opaque to other code. - Added a special CLUST_DEAD cluster type to indicate errors. sbin/fsck_msdosfs/ext.h: - Added a flag that overrides mmap(2) setting. The corresponding command line option, -M is intentionally undocumented as we do not expect users to need it. - Added accessors for FAT table and convert existing interface to use it. sbin/fsck_msdosfs/fat.c: - Added head bitmap to represent whether a cluster is a head cluster. - Converted FAT internal representation to accessors. - Implemented a LRU cache for FAT32 when mmap(2) should not or can not be used. - _readfat: Attempt a mmap(2) and fall back to regular read for non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate the cache with the first 4MiB of the entries. - readfat: Added support of head bitmap and use the population scan to detect bogus chains. - clusterdiff: removed, FATs are copied from the checked copy via writefat()/copyfat(). - checkchain: calculates the length of a cluster chain and make sure that it ends with a valid EOF marker. - clearchain: follow and clear a chain and maintain the free cluster count. - checklost: convert to use head bitmap. At the end of all other scans, the remaining 'head' nodes are leaders of lost cluster chains. sbin/fsck_msdosfs/fat.c: - Added a new -M option which is intentionally undocumented, to disable the use of mmap(). Reviewed by: kevlo MFC after: 1 month Relnotes: yes Differential Revision: https://reviews.freebsd.org/D22965
Notes
Notes: svn path=/head/; revision=356313
-rw-r--r--sbin/fsck_msdosfs/boot.c28
-rw-r--r--sbin/fsck_msdosfs/check.c49
-rw-r--r--sbin/fsck_msdosfs/dir.c362
-rw-r--r--sbin/fsck_msdosfs/dosfs.h10
-rw-r--r--sbin/fsck_msdosfs/ext.h47
-rw-r--r--sbin/fsck_msdosfs/fat.c1351
-rw-r--r--sbin/fsck_msdosfs/main.c8
7 files changed, 1217 insertions, 638 deletions
diff --git a/sbin/fsck_msdosfs/boot.c b/sbin/fsck_msdosfs/boot.c
index 61920e68af52..a3ba7abccb9a 100644
--- a/sbin/fsck_msdosfs/boot.c
+++ b/sbin/fsck_msdosfs/boot.c
@@ -152,9 +152,6 @@ readboot(int dosfs, struct bootblock *boot)
boot->NumSectors = boot->bpbHugeSectors;
}
-
-
-
if (boot->flags & FAT32) {
/* If the OEM Name field is EXFAT, it's not FAT32, so bail */
if (!memcmp(&block[3], "EXFAT ", 8)) {
@@ -272,13 +269,30 @@ readboot(int dosfs, struct bootblock *boot)
boot->NumClusters = (boot->NumSectors - boot->FirstCluster) / boot->bpbSecPerClust +
CLUST_FIRST;
- if (boot->flags & FAT32)
+ if (boot->flags & FAT32) {
+ if (boot->NumClusters > (CLUST_RSRVD & CLUST32_MASK)) {
+ pfatal("Filesystem too big (%u clusters) for FAT32 partition",
+ boot->NumClusters);
+ return FSFATAL;
+ }
+ if (boot->NumClusters < (CLUST_RSRVD & CLUST16_MASK)) {
+ pfatal("Filesystem too small (%u clusters) for FAT32 partition",
+ boot->NumClusters);
+ return FSFATAL;
+ }
boot->ClustMask = CLUST32_MASK;
- else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK))
+
+ if (boot->bpbRootClust < CLUST_FIRST ||
+ boot->bpbRootClust >= boot->NumClusters) {
+ pfatal("Root directory starts with cluster out of range(%u)",
+ boot->bpbRootClust);
+ return FSFATAL;
+ }
+ } else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK)) {
boot->ClustMask = CLUST12_MASK;
- else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK))
+ } else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK)) {
boot->ClustMask = CLUST16_MASK;
- else {
+ } else {
pfatal("Filesystem too big (%u clusters) for non-FAT32 partition",
boot->NumClusters);
return FSFATAL;
diff --git a/sbin/fsck_msdosfs/check.c b/sbin/fsck_msdosfs/check.c
index 2431bd38dd66..2c3866223a71 100644
--- a/sbin/fsck_msdosfs/check.c
+++ b/sbin/fsck_msdosfs/check.c
@@ -47,9 +47,8 @@ checkfilesys(const char *fname)
{
int dosfs;
struct bootblock boot;
- struct fatEntry *fat = NULL;
+ struct fat_descriptor *fat = NULL;
int finish_dosdirsection=0;
- u_int i;
int mod = 0;
int ret = 8;
@@ -88,65 +87,39 @@ checkfilesys(const char *fname)
}
if (!preen) {
- if (boot.ValidFat < 0)
- printf("** Phase 1 - Read and Compare FATs\n");
- else
- printf("** Phase 1 - Read FAT\n");
+ printf("** Phase 1 - Read FAT and checking connectivity\n");
}
- mod |= readfat(dosfs, &boot, boot.ValidFat >= 0 ? boot.ValidFat : 0, &fat);
+ mod |= readfat(dosfs, &boot, &fat);
if (mod & FSFATAL) {
close(dosfs);
return 8;
}
- if (boot.ValidFat < 0)
- for (i = 1; i < boot.bpbFATs; i++) {
- struct fatEntry *currentFat;
-
- mod |= readfat(dosfs, &boot, i, &currentFat);
-
- if (mod & FSFATAL)
- goto out;
-
- mod |= comparefat(&boot, fat, currentFat, i);
- free(currentFat);
- if (mod & FSFATAL)
- goto out;
- }
-
- if (!preen)
- printf("** Phase 2 - Check Cluster Chains\n");
-
- mod |= checkfat(&boot, fat);
- if (mod & FSFATAL)
- goto out;
- /* delay writing FATs */
-
if (!preen)
- printf("** Phase 3 - Checking Directories\n");
+ printf("** Phase 2 - Checking Directories\n");
- mod |= resetDosDirSection(&boot, fat);
+ mod |= resetDosDirSection(fat);
finish_dosdirsection = 1;
if (mod & FSFATAL)
goto out;
/* delay writing FATs */
- mod |= handleDirTree(dosfs, &boot, fat);
+ mod |= handleDirTree(fat);
if (mod & FSFATAL)
goto out;
if (!preen)
- printf("** Phase 4 - Checking for Lost Files\n");
+ printf("** Phase 3 - Checking for Lost Files\n");
- mod |= checklost(dosfs, &boot, fat);
+ mod |= checklost(fat);
if (mod & FSFATAL)
goto out;
/* now write the FATs */
- if (mod & (FSFATMOD|FSFIXFAT)) {
+ if (mod & FSFATMOD) {
if (ask(1, "Update FATs")) {
- mod |= writefat(dosfs, &boot, fat, mod & FSFIXFAT);
+ mod |= writefat(fat);
if (mod & FSFATAL)
goto out;
} else
@@ -170,7 +143,7 @@ checkfilesys(const char *fname)
if (mod & FSDIRTY) {
pwarn("MARKING FILE SYSTEM CLEAN\n");
- mod |= writefat(dosfs, &boot, fat, 1);
+ mod |= writefat(fat);
} else {
pwarn("\n***** FILE SYSTEM IS LEFT MARKED AS DIRTY *****\n");
mod |= FSERROR; /* file system not clean */
diff --git a/sbin/fsck_msdosfs/dir.c b/sbin/fsck_msdosfs/dir.c
index 7e459c75d4ff..6bdc3b4d0f94 100644
--- a/sbin/fsck_msdosfs/dir.c
+++ b/sbin/fsck_msdosfs/dir.c
@@ -1,6 +1,7 @@
/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
+ * Copyright (c) 2019 Google LLC
* Copyright (C) 1995, 1996, 1997 Wolfgang Solfrank
* Copyright (c) 1995 Martin Husemann
* Some structure declaration borrowed from Paul Popelka
@@ -95,14 +96,11 @@ static struct dirTodoNode *newDirTodo(void);
static void freeDirTodo(struct dirTodoNode *);
static char *fullpath(struct dosDirEntry *);
static u_char calcShortSum(u_char *);
-static int delete(int, struct bootblock *, struct fatEntry *, cl_t, int,
- cl_t, int, int);
-static int removede(int, struct bootblock *, struct fatEntry *, u_char *,
- u_char *, cl_t, cl_t, cl_t, char *, int);
-static int checksize(struct bootblock *, struct fatEntry *, u_char *,
- struct dosDirEntry *);
-static int readDosDirSection(int, struct bootblock *, struct fatEntry *,
- struct dosDirEntry *);
+static int delete(struct fat_descriptor *, cl_t, int, cl_t, int, int);
+static int removede(struct fat_descriptor *, u_char *, u_char *,
+ cl_t, cl_t, cl_t, char *, int);
+static int checksize(struct fat_descriptor *, u_char *, struct dosDirEntry *);
+static int readDosDirSection(struct fat_descriptor *, struct dosDirEntry *);
/*
* Manage free dosDirEntry structures.
@@ -116,7 +114,7 @@ newDosDirEntry(void)
if (!(de = freede)) {
if (!(de = malloc(sizeof *de)))
- return 0;
+ return (NULL);
} else
freede = de->next;
return de;
@@ -193,7 +191,7 @@ fullpath(struct dosDirEntry *dir)
/*
* Calculate a checksum over an 8.3 alias name
*/
-static u_char
+static inline u_char
calcShortSum(u_char *p)
{
u_char sum = 0;
@@ -221,21 +219,24 @@ static struct dosDirEntry *lostDir;
* Init internal state for a new directory scan.
*/
int
-resetDosDirSection(struct bootblock *boot, struct fatEntry *fat)
+resetDosDirSection(struct fat_descriptor *fat)
{
- int b1, b2;
+ int rootdir_size, cluster_size;
int ret = FSOK;
size_t len;
+ struct bootblock *boot;
+
+ boot = fat_get_boot(fat);
- b1 = boot->bpbRootDirEnts * 32;
- b2 = boot->bpbSecPerClust * boot->bpbBytesPerSec;
+ rootdir_size = boot->bpbRootDirEnts * 32;
+ cluster_size = boot->bpbSecPerClust * boot->bpbBytesPerSec;
- if ((buffer = malloc(len = MAX(b1, b2))) == NULL) {
+ if ((buffer = malloc(len = MAX(rootdir_size, cluster_size))) == NULL) {
perr("No space for directory buffer (%zu)", len);
return FSFATAL;
}
- if ((delbuf = malloc(len = b2)) == NULL) {
+ if ((delbuf = malloc(len = cluster_size)) == NULL) {
free(buffer);
perr("No space for directory delbuf (%zu)", len);
return FSFATAL;
@@ -250,18 +251,10 @@ resetDosDirSection(struct bootblock *boot, struct fatEntry *fat)
memset(rootDir, 0, sizeof *rootDir);
if (boot->flags & FAT32) {
- if (boot->bpbRootClust < CLUST_FIRST ||
- boot->bpbRootClust >= boot->NumClusters) {
- pfatal("Root directory starts with cluster out of range(%u)",
- boot->bpbRootClust);
- return FSFATAL;
- }
- if (fat[boot->bpbRootClust].head != boot->bpbRootClust) {
+ if (!fat_is_cl_head(fat, boot->bpbRootClust)) {
pfatal("Root directory doesn't start a cluster chain");
return FSFATAL;
}
-
- fat[boot->bpbRootClust].flags |= FAT_USED;
rootDir->head = boot->bpbRootClust;
}
@@ -302,16 +295,21 @@ finishDosDirSection(void)
* Delete directory entries between startcl, startoff and endcl, endoff.
*/
static int
-delete(int f, struct bootblock *boot, struct fatEntry *fat, cl_t startcl,
+delete(struct fat_descriptor *fat, cl_t startcl,
int startoff, cl_t endcl, int endoff, int notlast)
{
u_char *s, *e;
off_t off;
- int clsz = boot->bpbSecPerClust * boot->bpbBytesPerSec;
+ int clsz, fd;
+ struct bootblock *boot;
+
+ boot = fat_get_boot(fat);
+ fd = fat_get_fd(fat);
+ clsz = boot->bpbSecPerClust * boot->bpbBytesPerSec;
s = delbuf + startoff;
e = delbuf + clsz;
- while (startcl >= CLUST_FIRST && startcl < boot->NumClusters) {
+ while (fat_is_valid_cl(fat, startcl)) {
if (startcl == endcl) {
if (notlast)
break;
@@ -320,11 +318,11 @@ delete(int f, struct bootblock *boot, struct fatEntry *fat, cl_t startcl,
off = (startcl - CLUST_FIRST) * boot->bpbSecPerClust + boot->FirstCluster;
off *= boot->bpbBytesPerSec;
- if (lseek(f, off, SEEK_SET) != off) {
+ if (lseek(fd, off, SEEK_SET) != off) {
perr("Unable to lseek to %" PRId64, off);
return FSFATAL;
}
- if (read(f, delbuf, clsz) != clsz) {
+ if (read(fd, delbuf, clsz) != clsz) {
perr("Unable to read directory");
return FSFATAL;
}
@@ -332,25 +330,26 @@ delete(int f, struct bootblock *boot, struct fatEntry *fat, cl_t startcl,
*s = SLOT_DELETED;
s += 32;
}
- if (lseek(f, off, SEEK_SET) != off) {
+ if (lseek(fd, off, SEEK_SET) != off) {
perr("Unable to lseek to %" PRId64, off);
return FSFATAL;
}
- if (write(f, delbuf, clsz) != clsz) {
+ if (write(fd, delbuf, clsz) != clsz) {
perr("Unable to write directory");
return FSFATAL;
}
if (startcl == endcl)
break;
- startcl = fat[startcl].next;
+ startcl = fat_get_cl_next(fat, startcl);
s = delbuf;
}
return FSOK;
}
static int
-removede(int f, struct bootblock *boot, struct fatEntry *fat, u_char *start,
- u_char *end, cl_t startcl, cl_t endcl, cl_t curcl, char *path, int type)
+removede(struct fat_descriptor *fat, u_char *start,
+ u_char *end, cl_t startcl, cl_t endcl, cl_t curcl,
+ char *path, int type)
{
switch (type) {
case 0:
@@ -366,14 +365,14 @@ removede(int f, struct bootblock *boot, struct fatEntry *fat, u_char *start,
}
if (ask(0, "Remove")) {
if (startcl != curcl) {
- if (delete(f, boot, fat,
+ if (delete(fat,
startcl, start - buffer,
endcl, end - buffer,
endcl == curcl) == FSFATAL)
return FSFATAL;
start = buffer;
}
- /* startcl is < CLUST_FIRST for !fat32 root */
+ /* startcl is < CLUST_FIRST for !FAT32 root */
if ((endcl == curcl) || (startcl < CLUST_FIRST))
for (; start < end; start += 32)
*start = SLOT_DELETED;
@@ -386,23 +385,37 @@ removede(int f, struct bootblock *boot, struct fatEntry *fat, u_char *start,
* Check an in-memory file entry
*/
static int
-checksize(struct bootblock *boot, struct fatEntry *fat, u_char *p,
- struct dosDirEntry *dir)
+checksize(struct fat_descriptor *fat, u_char *p, struct dosDirEntry *dir)
{
+ int ret = FSOK;
+ size_t physicalSize;
+ struct bootblock *boot;
+
+ boot = fat_get_boot(fat);
+
/*
* Check size on ordinary files
*/
- u_int32_t physicalSize;
-
- if (dir->head == CLUST_FREE)
+ if (dir->head == CLUST_FREE) {
physicalSize = 0;
- else {
- if (dir->head < CLUST_FIRST || dir->head >= boot->NumClusters)
+ } else {
+ if (!fat_is_valid_cl(fat, dir->head))
return FSERROR;
- physicalSize = fat[dir->head].length * boot->ClusterSize;
+ ret = checkchain(fat, dir->head, &physicalSize);
+ /*
+ * Upon return, physicalSize would hold the chain length
+ * that checkchain() was able to validate, but if the user
+ * refused the proposed repair, it would be unsafe to
+ * proceed with directory entry fix, so bail out in that
+ * case.
+ */
+ if (ret == FSERROR) {
+ return (FSERROR);
+ }
+ physicalSize *= boot->ClusterSize;
}
if (physicalSize < dir->size) {
- pwarn("size of %s is %u, should at most be %u\n",
+ pwarn("size of %s is %u, should at most be %zu\n",
fullpath(dir), dir->size, physicalSize);
if (ask(1, "Truncate")) {
dir->size = physicalSize;
@@ -422,11 +435,10 @@ checksize(struct bootblock *boot, struct fatEntry *fat, u_char *p,
for (cl = dir->head, len = sz = 0;
(sz += boot->ClusterSize) < dir->size; len++)
- cl = fat[cl].next;
- clearchain(boot, fat, fat[cl].next);
- fat[cl].next = CLUST_EOF;
- fat[dir->head].length = len;
- return FSFATMOD;
+ cl = fat_get_cl_next(fat, cl);
+ clearchain(fat, fat_get_cl_next(fat, cl));
+ ret = fat_set_cl_next(fat, cl, CLUST_EOF);
+ return (FSFATMOD | ret);
} else
return FSERROR;
}
@@ -442,15 +454,20 @@ static const u_char dotdot_name[11] = ".. ";
* when we traverse into it.
*/
static int
-check_subdirectory(int f, struct bootblock *boot, struct dosDirEntry *dir)
+check_subdirectory(struct fat_descriptor *fat, struct dosDirEntry *dir)
{
u_char *buf, *cp;
off_t off;
cl_t cl;
int retval = FSOK;
+ int fd;
+ struct bootblock *boot;
+
+ boot = fat_get_boot(fat);
+ fd = fat_get_fd(fat);
cl = dir->head;
- if (dir->parent && (cl < CLUST_FIRST || cl >= boot->NumClusters)) {
+ if (dir->parent && !fat_is_valid_cl(fat, cl)) {
return FSERROR;
}
@@ -474,8 +491,8 @@ check_subdirectory(int f, struct bootblock *boot, struct dosDirEntry *dir)
}
off *= boot->bpbBytesPerSec;
- if (lseek(f, off, SEEK_SET) != off ||
- read(f, buf, boot->bpbBytesPerSec) != (ssize_t)boot->bpbBytesPerSec) {
+ if (lseek(fd, off, SEEK_SET) != off ||
+ read(fd, buf, boot->bpbBytesPerSec) != (ssize_t)boot->bpbBytesPerSec) {
perr("Unable to read directory");
free(buf);
return FSFATAL;
@@ -509,22 +526,27 @@ check_subdirectory(int f, struct bootblock *boot, struct dosDirEntry *dir)
* - push directories onto the todo-stack
*/
static int
-readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat,
- struct dosDirEntry *dir)
+readDosDirSection(struct fat_descriptor *fat, struct dosDirEntry *dir)
{
+ struct bootblock *boot;
struct dosDirEntry dirent, *d;
u_char *p, *vallfn, *invlfn, *empty;
off_t off;
- int i, j, k, last;
+ int fd, i, j, k, iosize, entries;
+ bool is_legacyroot;
cl_t cl, valcl = ~0, invcl = ~0, empcl = ~0;
char *t;
u_int lidx = 0;
int shortSum;
int mod = FSOK;
+ size_t dirclusters;
#define THISMOD 0x8000 /* Only used within this routine */
+ boot = fat_get_boot(fat);
+ fd = fat_get_fd(fat);
+
cl = dir->head;
- if (dir->parent && (cl < CLUST_FIRST || cl >= boot->NumClusters)) {
+ if (dir->parent && (!fat_is_valid_cl(fat, cl))) {
/*
* Already handled somewhere else.
*/
@@ -532,24 +554,50 @@ readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat,
}
shortSum = -1;
vallfn = invlfn = empty = NULL;
+
+ /*
+ * If we are checking the legacy root (for FAT12/FAT16),
+ * we will operate on the whole directory; otherwise, we
+ * will operate on one cluster at a time, and also take
+ * this opportunity to examine the chain.
+ *
+ * Derive how many entries we are going to encounter from
+ * the I/O size.
+ */
+ is_legacyroot = (dir->parent == NULL && !(boot->flags & FAT32));
+ if (is_legacyroot) {
+ iosize = boot->bpbRootDirEnts * 32;
+ entries = boot->bpbRootDirEnts;
+ } else {
+ iosize = boot->bpbSecPerClust * boot->bpbBytesPerSec;
+ entries = iosize / 32;
+ mod |= checkchain(fat, dir->head, &dirclusters);
+ }
+
do {
- if (!(boot->flags & FAT32) && !dir->parent) {
- last = boot->bpbRootDirEnts * 32;
+ if (is_legacyroot) {
+ /*
+ * Special case for FAT12/FAT16 root -- read
+ * in the whole root directory.
+ */
off = boot->bpbResSectors + boot->bpbFATs *
boot->FATsecs;
} else {
- last = boot->bpbSecPerClust * boot->bpbBytesPerSec;
+ /*
+ * Otherwise, read in a cluster of the
+ * directory.
+ */
off = (cl - CLUST_FIRST) * boot->bpbSecPerClust + boot->FirstCluster;
}
off *= boot->bpbBytesPerSec;
- if (lseek(f, off, SEEK_SET) != off
- || read(f, buffer, last) != last) {
+ if (lseek(fd, off, SEEK_SET) != off ||
+ read(fd, buffer, iosize) != iosize) {
perr("Unable to read directory");
return FSFATAL;
}
- last /= 32;
- for (p = buffer, i = 0; i < last; i++, p += 32) {
+
+ for (p = buffer, i = 0; i < entries; i++, p += 32) {
if (dir->fsckflags & DIREMPWARN) {
*p = SLOT_EMPTY;
continue;
@@ -572,7 +620,7 @@ readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat,
u_char *q;
dir->fsckflags &= ~DIREMPTY;
- if (delete(f, boot, fat,
+ if (delete(fat,
empcl, empty - buffer,
cl, p - buffer, 1) == FSFATAL)
return FSFATAL;
@@ -701,7 +749,7 @@ readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat,
if (dirent.flags & ATTR_VOLUME) {
if (vallfn || invlfn) {
- mod |= removede(f, boot, fat,
+ mod |= removede(fat,
invlfn ? invlfn : vallfn, p,
invlfn ? invcl : valcl, -1, 0,
fullpath(dir), 2);
@@ -741,7 +789,7 @@ readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat,
dirent.next = dir->child;
if (invlfn) {
- mod |= k = removede(f, boot, fat,
+ mod |= k = removede(fat,
invlfn, vallfn ? vallfn : p,
invcl, vallfn ? valcl : cl, cl,
fullpath(&dirent), 0);
@@ -757,74 +805,61 @@ readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat,
vallfn = NULL; /* not used any longer */
invlfn = NULL;
- if (dirent.size == 0 && !(dirent.flags & ATTR_DIRECTORY)) {
- if (dirent.head != 0) {
- pwarn("%s has clusters, but size 0\n",
- fullpath(&dirent));
- if (ask(1, "Drop allocated clusters")) {
- p[26] = p[27] = 0;
- if (boot->ClustMask == CLUST32_MASK)
- p[20] = p[21] = 0;
- clearchain(boot, fat, dirent.head);
- dirent.head = 0;
- mod |= THISMOD|FSDIRMOD|FSFATMOD;
- } else
- mod |= FSERROR;
- }
- } else if (dirent.head == 0
- && !strcmp(dirent.name, "..")
- && dir->parent /* XXX */
- && !dir->parent->parent) {
- /*
- * Do nothing, the parent is the root
- */
- } else if (dirent.head < CLUST_FIRST
- || dirent.head >= boot->NumClusters
- || fat[dirent.head].next == CLUST_FREE
- || (fat[dirent.head].next >= CLUST_RSRVD
- && fat[dirent.head].next < CLUST_EOFS)
- || fat[dirent.head].head != dirent.head) {
- if (dirent.head == 0)
- pwarn("%s has no clusters\n",
- fullpath(&dirent));
- else if (dirent.head < CLUST_FIRST
- || dirent.head >= boot->NumClusters)
- pwarn("%s starts with cluster out of range(%u)\n",
- fullpath(&dirent),
- dirent.head);
- else if (fat[dirent.head].next == CLUST_FREE)
- pwarn("%s starts with free cluster\n",
- fullpath(&dirent));
- else if (fat[dirent.head].next >= CLUST_RSRVD)
- pwarn("%s starts with cluster marked %s\n",
- fullpath(&dirent),
- rsrvdcltype(fat[dirent.head].next));
- else
- pwarn("%s doesn't start a cluster chain\n",
- fullpath(&dirent));
- if (dirent.flags & ATTR_DIRECTORY) {
- if (ask(0, "Remove")) {
- *p = SLOT_DELETED;
- mod |= THISMOD|FSDIRMOD;
- } else
- mod |= FSERROR;
- continue;
- } else {
- if (ask(1, "Truncate")) {
- p[28] = p[29] = p[30] = p[31] = 0;
- p[26] = p[27] = 0;
- if (boot->ClustMask == CLUST32_MASK)
- p[20] = p[21] = 0;
- dirent.size = 0;
- mod |= THISMOD|FSDIRMOD;
- } else
- mod |= FSERROR;
+ /*
+ * Check if the directory entry is sane.
+ *
+ * '.' and '..' are skipped, their sanity is
+ * checked somewhere else.
+ *
+ * For everything else, check if we have a new,
+ * valid cluster chain (beginning of a file or
+ * directory that was never previously claimed
+ * by another file) when it's a non-empty file
+ * or a directory. The sanity of the cluster
+ * chain is checked at a later time when we
+ * traverse into the directory, or examine the
+ * file's directory entry.
+ *
+ * The only possible fix is to delete the entry
+ * if it's a directory; for file, we have to
+ * truncate the size to 0.
+ */
+ if (!(dirent.flags & ATTR_DIRECTORY) ||
+ (strcmp(dirent.name, ".") != 0 &&
+ strcmp(dirent.name, "..") != 0)) {
+ if ((dirent.size != 0 || (dirent.flags & ATTR_DIRECTORY)) &&
+ ((!fat_is_valid_cl(fat, dirent.head) ||
+ !fat_is_cl_head(fat, dirent.head)))) {
+ if (!fat_is_valid_cl(fat, dirent.head)) {
+ pwarn("%s starts with cluster out of range(%u)\n",
+ fullpath(&dirent),
+ dirent.head);
+ } else {
+ pwarn("%s doesn't start a new cluster chain\n",
+ fullpath(&dirent));
+ }
+
+ if (dirent.flags & ATTR_DIRECTORY) {
+ if (ask(0, "Remove")) {
+ *p = SLOT_DELETED;
+ mod |= THISMOD|FSDIRMOD;
+ } else
+ mod |= FSERROR;
+ continue;
+ } else {
+ if (ask(1, "Truncate")) {
+ p[28] = p[29] = p[30] = p[31] = 0;
+ p[26] = p[27] = 0;
+ if (boot->ClustMask == CLUST32_MASK)
+ p[20] = p[21] = 0;
+ dirent.size = 0;
+ dirent.head = 0;
+ mod |= THISMOD|FSDIRMOD;
+ } else
+ mod |= FSERROR;
+ }
}
}
-
- if (dirent.head >= CLUST_FIRST && dirent.head < boot->NumClusters)
- fat[dirent.head].flags |= FAT_USED;
-
if (dirent.flags & ATTR_DIRECTORY) {
/*
* gather more info for directories
@@ -861,8 +896,7 @@ readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat,
mod |= FSERROR;
}
continue;
- }
- if (strcmp(dirent.name, "..") == 0) {
+ } else if (strcmp(dirent.name, "..") == 0) {
if (dir->parent) { /* XXX */
if (!dir->parent->parent) {
if (dirent.head) {
@@ -908,7 +942,7 @@ readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat,
} else
mod |= FSERROR;
continue;
- } else if ((check_subdirectory(f, boot,
+ } else if ((check_subdirectory(fat,
&dirent) & FSERROR) == FSERROR) {
/*
* A subdirectory should have
@@ -944,39 +978,43 @@ readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat,
n->dir = d;
pendingDirectories = n;
} else {
- mod |= k = checksize(boot, fat, p, &dirent);
+ mod |= k = checksize(fat, p, &dirent);
if (k & FSDIRMOD)
mod |= THISMOD;
}
boot->NumFiles++;
}
- if (!(boot->flags & FAT32) && !dir->parent)
+ if (is_legacyroot) {
+ /*
+ * Don't bother to write back right now because
+ * we may continue to make modification to the
+ * non-FAT32 root directory below.
+ */
break;
-
- if (mod & THISMOD) {
- last *= 32;
- if (lseek(f, off, SEEK_SET) != off
- || write(f, buffer, last) != last) {
+ } else if (mod & THISMOD) {
+ if (lseek(fd, off, SEEK_SET) != off
+ || write(fd, buffer, iosize) != iosize) {
perr("Unable to write directory");
return FSFATAL;
}
mod &= ~THISMOD;
}
- } while ((cl = fat[cl].next) >= CLUST_FIRST && cl < boot->NumClusters);
+ } while (fat_is_valid_cl(fat, (cl = fat_get_cl_next(fat, cl))));
if (invlfn || vallfn)
- mod |= removede(f, boot, fat,
+ mod |= removede(fat,
invlfn ? invlfn : vallfn, p,
invlfn ? invcl : valcl, -1, 0,
fullpath(dir), 1);
- /* The root directory of non fat32 filesystems is in a special
- * area and may have been modified above without being written out.
+ /*
+ * The root directory of non-FAT32 filesystems is in a special
+ * area and may have been modified above removede() without
+ * being written out.
*/
- if ((mod & FSDIRMOD) && !(boot->flags & FAT32) && !dir->parent) {
- last *= 32;
- if (lseek(f, off, SEEK_SET) != off
- || write(f, buffer, last) != last) {
+ if ((mod & FSDIRMOD) && is_legacyroot) {
+ if (lseek(fd, off, SEEK_SET) != off
+ || write(fd, buffer, iosize) != iosize) {
perr("Unable to write directory");
return FSFATAL;
}
@@ -986,11 +1024,11 @@ readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat,
}
int
-handleDirTree(int dosfs, struct bootblock *boot, struct fatEntry *fat)
+handleDirTree(struct fat_descriptor *fat)
{
int mod;
- mod = readDosDirSection(dosfs, boot, fat, rootDir);
+ mod = readDosDirSection(fat, rootDir);
if (mod & FSFATAL)
return FSFATAL;
@@ -1011,7 +1049,7 @@ handleDirTree(int dosfs, struct bootblock *boot, struct fatEntry *fat)
/*
* handle subdirectory
*/
- mod |= readDosDirSection(dosfs, boot, fat, dir);
+ mod |= readDosDirSection(fat, dir);
if (mod & FSFATAL)
return FSFATAL;
}
@@ -1027,12 +1065,15 @@ static cl_t lfcl;
static off_t lfoff;
int
-reconnect(int dosfs, struct bootblock *boot, struct fatEntry *fat, cl_t head)
+reconnect(struct fat_descriptor *fat, cl_t head, size_t length)
{
+ struct bootblock *boot = fat_get_boot(fat);
struct dosDirEntry d;
- int len;
+ int len, dosfs;
u_char *p;
+ dosfs = fat_get_fd(fat);
+
if (!ask(1, "Reconnect"))
return FSERROR;
@@ -1063,7 +1104,7 @@ reconnect(int dosfs, struct bootblock *boot, struct fatEntry *fat, cl_t head)
break;
if (p && p < lfbuf + boot->ClusterSize)
break;
- lfcl = p ? fat[lfcl].next : lostDir->head;
+ lfcl = p ? fat_get_cl_next(fat, lfcl) : lostDir->head;
if (lfcl < CLUST_FIRST || lfcl >= boot->NumClusters) {
/* Extend LOSTDIR? XXX */
pwarn("No space in %s\n", LOSTDIR);
@@ -1088,7 +1129,7 @@ reconnect(int dosfs, struct bootblock *boot, struct fatEntry *fat, cl_t head)
len = snprintf(d.name, sizeof(d.name), "%u", head);
d.flags = 0;
d.head = head;
- d.size = fat[head].length * boot->ClusterSize;
+ d.size = length * boot->ClusterSize;
memcpy(p, d.name, len);
memset(p + len, ' ', 11 - len);
@@ -1103,7 +1144,6 @@ reconnect(int dosfs, struct bootblock *boot, struct fatEntry *fat, cl_t head)
p[29] = (u_char)(d.size >> 8);
p[30] = (u_char)(d.size >> 16);
p[31] = (u_char)(d.size >> 24);
- fat[head].flags |= FAT_USED;
if (lseek(dosfs, lfoff, SEEK_SET) != lfoff
|| (size_t)write(dosfs, lfbuf, boot->ClusterSize) != boot->ClusterSize) {
perr("could not write LOST.DIR");
diff --git a/sbin/fsck_msdosfs/dosfs.h b/sbin/fsck_msdosfs/dosfs.h
index 9f1480f17b00..d89a08689825 100644
--- a/sbin/fsck_msdosfs/dosfs.h
+++ b/sbin/fsck_msdosfs/dosfs.h
@@ -83,19 +83,13 @@ struct bootblock {
u_int NumBad; /* # of bad clusters */
};
-struct fatEntry {
- cl_t next; /* pointer to next cluster */
- cl_t head; /* pointer to start of chain */
- u_int32_t length; /* number of clusters on chain */
- int flags; /* see below */
-};
-
#define CLUST_FREE 0 /* 0 means cluster is free */
#define CLUST_FIRST 2 /* 2 is the minimum valid cluster number */
#define CLUST_RSRVD 0xfffffff6 /* start of reserved clusters */
#define CLUST_BAD 0xfffffff7 /* a cluster with a defect */
#define CLUST_EOFS 0xfffffff8 /* start of EOF indicators */
#define CLUST_EOF 0xffffffff /* standard value for last cluster */
+#define CLUST_DEAD 0xfdeadc0d /* error encountered */
/*
* Masks for cluster values
@@ -104,8 +98,6 @@ struct fatEntry {
#define CLUST16_MASK 0xffff
#define CLUST32_MASK 0xfffffff
-#define FAT_USED 1 /* This fat chain is used in a file */
-
#define DOSLONGNAMELEN 256 /* long name maximal length */
#define LRFIRST 0x40 /* first long name record */
#define LRNOMASK 0x1f /* mask to extract long record
diff --git a/sbin/fsck_msdosfs/ext.h b/sbin/fsck_msdosfs/ext.h
index ebc94677b9b3..6e9ba7f56b3a 100644
--- a/sbin/fsck_msdosfs/ext.h
+++ b/sbin/fsck_msdosfs/ext.h
@@ -32,6 +32,8 @@
#include <sys/types.h>
+#include <stdbool.h>
+
#include "dosfs.h"
#define LOSTDIR "LOST.DIR"
@@ -44,6 +46,7 @@ extern int alwaysyes; /* assume "yes" for all questions */
extern int preen; /* we are preening */
extern int rdonly; /* device is opened read only (supersedes above) */
extern int skipclean; /* skip clean file systems if preening */
+extern int allow_mmap; /* allow the use of mmap() */
/*
* function declarations
@@ -72,7 +75,6 @@ int checkfilesys(const char *);
#define FSERROR 8 /* Some unrecovered error remains */
#define FSFATAL 16 /* Some unrecoverable error occurred */
#define FSDIRTY 32 /* File system is dirty */
-#define FSFIXFAT 64 /* Fix file system FAT */
/*
* read a boot block in a machine independent fashion and translate
@@ -85,46 +87,53 @@ int readboot(int, struct bootblock *);
*/
int writefsinfo(int, struct bootblock *);
-/*
- * Read one of the FAT copies and return a pointer to the new
- * allocated array holding our description of it.
- */
-int readfat(int, struct bootblock *, u_int, struct fatEntry **);
+/* Opaque type */
+struct fat_descriptor;
-/*
- * Check two FAT copies for consistency and merge changes into the
- * first if necessary.
- */
-int comparefat(struct bootblock *, struct fatEntry *, struct fatEntry *, u_int);
+void fat_clear_cl_head(struct fat_descriptor *, cl_t);
+bool fat_is_cl_head(struct fat_descriptor *, cl_t);
+
+cl_t fat_get_cl_next(struct fat_descriptor *, cl_t);
+
+int fat_set_cl_next(struct fat_descriptor *, cl_t, cl_t);
+
+cl_t fat_allocate_cluster(struct fat_descriptor *fat);
+
+struct bootblock* fat_get_boot(struct fat_descriptor *);
+int fat_get_fd(struct fat_descriptor *);
+bool fat_is_valid_cl(struct fat_descriptor *, cl_t);
/*
- * Check a FAT
+ * Read the FAT 0 and return a pointer to the newly allocated
+ * descriptor of it.
*/
-int checkfat(struct bootblock *, struct fatEntry *);
+int readfat(int, struct bootblock *, struct fat_descriptor **);
/*
* Write back FAT entries
*/
-int writefat(int, struct bootblock *, struct fatEntry *, int);
+int writefat(struct fat_descriptor *);
/*
* Read a directory
*/
-int resetDosDirSection(struct bootblock *, struct fatEntry *);
+int resetDosDirSection(struct fat_descriptor *);
void finishDosDirSection(void);
-int handleDirTree(int, struct bootblock *, struct fatEntry *);
+int handleDirTree(struct fat_descriptor *);
/*
* Cross-check routines run after everything is completely in memory
*/
+int checkchain(struct fat_descriptor *, cl_t, size_t *);
+
/*
* Check for lost cluster chains
*/
-int checklost(int, struct bootblock *, struct fatEntry *);
+int checklost(struct fat_descriptor *);
/*
* Try to reconnect a lost cluster chain
*/
-int reconnect(int, struct bootblock *, struct fatEntry *, cl_t);
+int reconnect(struct fat_descriptor *, cl_t, size_t);
void finishlf(void);
/*
@@ -138,6 +147,6 @@ const char *rsrvdcltype(cl_t);
/*
* Clear a cluster chain in a FAT
*/
-void clearchain(struct bootblock *, struct fatEntry *, cl_t);
+void clearchain(struct fat_descriptor *, cl_t);
#endif
diff --git a/sbin/fsck_msdosfs/fat.c b/sbin/fsck_msdosfs/fat.c
index 7ca81ab115ef..12050c2591d4 100644
--- a/sbin/fsck_msdosfs/fat.c
+++ b/sbin/fsck_msdosfs/fat.c
@@ -1,6 +1,7 @@
/*-
* SPDX-License-Identifier: BSD-2-Clause
*
+ * Copyright (c) 2019 Google LLC
* Copyright (C) 1995, 1996, 1997 Wolfgang Solfrank
* Copyright (c) 1995 Martin Husemann
*
@@ -33,6 +34,14 @@ static const char rcsid[] =
"$FreeBSD$";
#endif /* not lint */
+#include <sys/endian.h>
+#include <sys/queue.h>
+#include <sys/limits.h>
+#include <sys/mman.h>
+#include <sys/param.h>
+
+#include <assert.h>
+#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
@@ -42,12 +51,517 @@ static const char rcsid[] =
#include "ext.h"
#include "fsutil.h"
-static int checkclnum(struct bootblock *, u_int, cl_t, cl_t *);
-static int clustdiffer(cl_t, cl_t *, cl_t *, u_int);
-static int tryclear(struct bootblock *, struct fatEntry *, cl_t, cl_t *);
-static int _readfat(int, struct bootblock *, u_int, u_char **);
+static int _readfat(struct fat_descriptor *);
+static inline struct bootblock* boot_of_(struct fat_descriptor *);
+static inline int fd_of_(struct fat_descriptor *);
+static inline bool valid_cl(struct fat_descriptor *, cl_t);
-/*-
+
+/*
+ * Head bitmap for FAT scanning.
+ *
+ * FAT32 have up to 2^28 = 256M entries, and FAT16/12 have much less.
+ * For each cluster, we use 1 bit to represent if it's a head cluster
+ * (the first cluster of a cluster chain).
+ *
+ * Head bitmap
+ * ===========
+ * Initially, we set all bits to 1. In readfat(), we traverse the
+ * whole FAT and mark each cluster identified as "next" cluster as
+ * 0. After the scan, we have a bitmap with 1's to indicate the
+ * corresponding cluster was a "head" cluster.
+ *
+ * We use head bitmap to identify lost chains: a head cluster that was
+ * not being claimed by any file or directories is the head cluster of
+ * a lost chain.
+ *
+ * Handle of lost chains
+ * =====================
+ * At the end of scanning, we can easily find all lost chain's heads
+ * by finding out the 1's in the head bitmap.
+ */
+
+typedef struct long_bitmap {
+ unsigned long *map;
+ size_t count; /* Total set bits in the map */
+} long_bitmap_t;
+
+static inline void
+bitmap_clear(long_bitmap_t *lbp, cl_t cl)
+{
+ cl_t i = cl / LONG_BIT;
+ unsigned long clearmask = ~(1UL << (cl % LONG_BIT));
+
+ assert((lbp->map[i] & ~clearmask) != 0);
+ lbp->map[i] &= clearmask;
+ lbp->count--;
+}
+
+static inline bool
+bitmap_get(long_bitmap_t *lbp, cl_t cl)
+{
+ cl_t i = cl / LONG_BIT;
+ unsigned long usedbit = 1UL << (cl % LONG_BIT);
+
+ return ((lbp->map[i] & usedbit) == usedbit);
+}
+
+static inline bool
+bitmap_none_in_range(long_bitmap_t *lbp, cl_t cl)
+{
+ cl_t i = cl / LONG_BIT;
+
+ return (lbp->map[i] == 0);
+}
+
+static inline size_t
+bitmap_count(long_bitmap_t *lbp)
+{
+ return (lbp->count);
+}
+
+static int
+bitmap_ctor(long_bitmap_t *lbp, size_t bits, bool allone)
+{
+ size_t bitmap_size = roundup2(bits, LONG_BIT) / (LONG_BIT / 8);
+
+ free(lbp->map);
+ lbp->map = calloc(1, bitmap_size);
+ if (lbp->map == NULL)
+ return FSFATAL;
+
+ if (allone) {
+ memset(lbp->map, 0xff, bitmap_size);
+ lbp->count = bits;
+ } else {
+ lbp->count = 0;
+ }
+ return FSOK;
+}
+
+static void
+bitmap_dtor(long_bitmap_t *lbp)
+{
+ free(lbp->map);
+ lbp->map = NULL;
+}
+
+/*
+ * FAT32 can be as big as 256MiB (2^26 entries * 4 bytes), when we
+ * can not ask the kernel to manage the access, use a simple LRU
+ * cache with chunk size of 128 KiB to manage it.
+ */
+struct fat32_cache_entry {
+ TAILQ_ENTRY(fat32_cache_entry) entries;
+ uint8_t *chunk; /* pointer to chunk */
+ off_t addr; /* offset */
+ bool dirty; /* dirty bit */
+};
+
+static const size_t fat32_cache_chunk_size = 131072; /* MAXPHYS */
+static const size_t fat32_cache_size = 4194304;
+static const size_t fat32_cache_entries = 32; /* XXXgcc: cache_size / cache_chunk_size */
+
+/*
+ * FAT table descriptor, represents a FAT table that is already loaded
+ * into memory.
+ */
+struct fat_descriptor {
+ struct bootblock *boot;
+ uint8_t *fatbuf;
+ cl_t (*get)(struct fat_descriptor *, cl_t);
+ int (*set)(struct fat_descriptor *, cl_t, cl_t);
+ long_bitmap_t headbitmap;
+ int fd;
+ bool is_mmapped;
+ bool use_cache;
+ size_t fatsize;
+
+ size_t fat32_cached_chunks;
+ TAILQ_HEAD(cachehead, fat32_cache_entry) fat32_cache_head;
+ struct fat32_cache_entry *fat32_cache_allentries;
+ off_t fat32_offset;
+ off_t fat32_lastaddr;
+};
+
+void
+fat_clear_cl_head(struct fat_descriptor *fat, cl_t cl)
+{
+ bitmap_clear(&fat->headbitmap, cl);
+}
+
+bool
+fat_is_cl_head(struct fat_descriptor *fat, cl_t cl)
+{
+ return (bitmap_get(&fat->headbitmap, cl));
+}
+
+static inline bool
+fat_is_cl_head_in_range(struct fat_descriptor *fat, cl_t cl)
+{
+ return (!(bitmap_none_in_range(&fat->headbitmap, cl)));
+}
+
+static size_t
+fat_get_head_count(struct fat_descriptor *fat)
+{
+ return (bitmap_count(&fat->headbitmap));
+}
+
+/*
+ * FAT12 accessors.
+ *
+ * FAT12s are sufficiently small, expect it to always fit in the RAM.
+ */
+static inline uint8_t *
+fat_get_fat12_ptr(struct fat_descriptor *fat, cl_t cl)
+{
+ return (fat->fatbuf + ((cl + (cl >> 1))));
+}
+
+static cl_t
+fat_get_fat12_next(struct fat_descriptor *fat, cl_t cl)
+{
+ const uint8_t *p;
+ cl_t retval;
+
+ p = fat_get_fat12_ptr(fat, cl);
+ retval = le16dec(p);
+ /* Odd cluster: lower 4 bits belongs to the subsequent cluster */
+ if ((cl & 1) == 1)
+ retval >>= 4;
+ retval &= CLUST12_MASK;
+
+ if (retval >= (CLUST_BAD & CLUST12_MASK))
+ retval |= ~CLUST12_MASK;
+
+ return (retval);
+}
+
+static int
+fat_set_fat12_next(struct fat_descriptor *fat, cl_t cl, cl_t nextcl)
+{
+ uint8_t *p;
+
+ /* Truncate 'nextcl' value, if needed */
+ nextcl &= CLUST12_MASK;
+
+ p = fat_get_fat12_ptr(fat, cl);
+
+ /*
+ * Read in the 4 bits from the subsequent (for even clusters)
+ * or the preceding (for odd clusters) cluster and combine
+ * it to the nextcl value for encoding
+ */
+ if ((cl & 1) == 0) {
+ nextcl |= ((p[1] & 0xf0) << 8);
+ } else {
+ nextcl <<= 4;
+ nextcl |= (p[0] & 0x0f);
+ }
+
+ le16enc(p, (uint16_t)nextcl);
+
+ return (0);
+}
+
+/*
+ * FAT16 accessors.
+ *
+ * FAT16s are sufficiently small, expect it to always fit in the RAM.
+ */
+static inline uint8_t *
+fat_get_fat16_ptr(struct fat_descriptor *fat, cl_t cl)
+{
+ return (fat->fatbuf + (cl << 1));
+}
+
+static cl_t
+fat_get_fat16_next(struct fat_descriptor *fat, cl_t cl)
+{
+ const uint8_t *p;
+ cl_t retval;
+
+ p = fat_get_fat16_ptr(fat, cl);
+ retval = le16dec(p) & CLUST16_MASK;
+
+ if (retval >= (CLUST_BAD & CLUST16_MASK))
+ retval |= ~CLUST16_MASK;
+
+ return (retval);
+}
+
+static int
+fat_set_fat16_next(struct fat_descriptor *fat, cl_t cl, cl_t nextcl)
+{
+ uint8_t *p;
+
+ /* Truncate 'nextcl' value, if needed */
+ nextcl &= CLUST16_MASK;
+
+ p = fat_get_fat16_ptr(fat, cl);
+
+ le16enc(p, (uint16_t)nextcl);
+
+ return (0);
+}
+
+/*
+ * FAT32 accessors.
+ */
+static inline uint8_t *
+fat_get_fat32_ptr(struct fat_descriptor *fat, cl_t cl)
+{
+ return (fat->fatbuf + (cl << 2));
+}
+
+static cl_t
+fat_get_fat32_next(struct fat_descriptor *fat, cl_t cl)
+{
+ const uint8_t *p;
+ cl_t retval;
+
+ p = fat_get_fat32_ptr(fat, cl);
+ retval = le32dec(p) & CLUST32_MASK;
+
+ if (retval >= (CLUST_BAD & CLUST32_MASK))
+ retval |= ~CLUST32_MASK;
+
+ return (retval);
+}
+
+static int
+fat_set_fat32_next(struct fat_descriptor *fat, cl_t cl, cl_t nextcl)
+{
+ uint8_t *p;
+
+ /* Truncate 'nextcl' value, if needed */
+ nextcl &= CLUST32_MASK;
+
+ p = fat_get_fat32_ptr(fat, cl);
+
+ le32enc(p, (uint32_t)nextcl);
+
+ return (0);
+}
+
+static inline size_t
+fat_get_iosize(struct fat_descriptor *fat, off_t address)
+{
+
+ if (address == fat->fat32_lastaddr) {
+ return (fat->fatsize & ((off_t)fat32_cache_chunk_size - 1));
+ } else {
+ return (fat32_cache_chunk_size);
+ }
+}
+
+static int
+fat_flush_fat32_cache_entry(struct fat_descriptor *fat,
+ struct fat32_cache_entry *entry)
+{
+ int fd;
+ off_t fat_addr;
+ size_t writesize;
+
+ fd = fd_of_(fat);
+
+ if (!entry->dirty)
+ return (FSOK);
+
+ writesize = fat_get_iosize(fat, entry->addr);
+
+ fat_addr = fat->fat32_offset + entry->addr;
+ if (lseek(fd, fat_addr, SEEK_SET) != fat_addr ||
+ (size_t)write(fd, entry->chunk, writesize) != writesize) {
+ pfatal("Unable to write FAT");
+ return (FSFATAL);
+ }
+
+ entry->dirty = false;
+ return (FSOK);
+}
+
+static struct fat32_cache_entry *
+fat_get_fat32_cache_entry(struct fat_descriptor *fat, off_t addr,
+ bool writing)
+{
+ int fd;
+ struct fat32_cache_entry *entry, *first;
+ off_t fat_addr;
+ size_t rwsize;
+
+ addr &= ~(fat32_cache_chunk_size - 1);
+
+ first = TAILQ_FIRST(&fat->fat32_cache_head);
+
+ /*
+ * Cache hit: if we already have the chunk, move it to list head
+ */
+ TAILQ_FOREACH(entry, &fat->fat32_cache_head, entries) {
+ if (entry->addr == addr) {
+ if (writing) {
+ entry->dirty = true;
+ }
+ if (entry != first) {
+
+ TAILQ_REMOVE(&fat->fat32_cache_head, entry, entries);
+ TAILQ_INSERT_HEAD(&fat->fat32_cache_head, entry, entries);
+ }
+ return (entry);
+ }
+ }
+
+ /*
+ * Cache miss: detach the chunk at tail of list, overwrite with
+ * the located chunk, and populate with data from disk.
+ */
+ entry = TAILQ_LAST(&fat->fat32_cache_head, cachehead);
+ TAILQ_REMOVE(&fat->fat32_cache_head, entry, entries);
+ if (fat_flush_fat32_cache_entry(fat, entry) != FSOK) {
+ return (NULL);
+ }
+
+ rwsize = fat_get_iosize(fat, addr);
+ fat_addr = fat->fat32_offset + addr;
+ entry->addr = addr;
+ fd = fd_of_(fat);
+ if (lseek(fd, fat_addr, SEEK_SET) != fat_addr ||
+ (size_t)read(fd, entry->chunk, rwsize) != rwsize) {
+ pfatal("Unable to read FAT");
+ return (NULL);
+ }
+ if (writing) {
+ entry->dirty = true;
+ }
+ TAILQ_INSERT_HEAD(&fat->fat32_cache_head, entry, entries);
+
+ return (entry);
+}
+
+static inline uint8_t *
+fat_get_fat32_cached_ptr(struct fat_descriptor *fat, cl_t cl, bool writing)
+{
+ off_t addr, off;
+ struct fat32_cache_entry *entry;
+
+ addr = cl << 2;
+ entry = fat_get_fat32_cache_entry(fat, addr, writing);
+
+ if (entry != NULL) {
+ off = addr & (fat32_cache_chunk_size - 1);
+ return (entry->chunk + off);
+ } else {
+ return (NULL);
+ }
+}
+
+
+static cl_t
+fat_get_fat32_cached_next(struct fat_descriptor *fat, cl_t cl)
+{
+ const uint8_t *p;
+ cl_t retval;
+
+ p = fat_get_fat32_cached_ptr(fat, cl, false);
+ if (p != NULL) {
+ retval = le32dec(p) & CLUST32_MASK;
+ if (retval >= (CLUST_BAD & CLUST32_MASK))
+ retval |= ~CLUST32_MASK;
+ } else {
+ retval = CLUST_DEAD;
+ }
+
+ return (retval);
+}
+
+static int
+fat_set_fat32_cached_next(struct fat_descriptor *fat, cl_t cl, cl_t nextcl)
+{
+ uint8_t *p;
+
+ /* Truncate 'nextcl' value, if needed */
+ nextcl &= CLUST32_MASK;
+
+ p = fat_get_fat32_cached_ptr(fat, cl, true);
+ if (p != NULL) {
+ le32enc(p, (uint32_t)nextcl);
+ return FSOK;
+ } else {
+ return FSFATAL;
+ }
+}
+
+cl_t fat_get_cl_next(struct fat_descriptor *fat, cl_t cl)
+{
+
+ if (!valid_cl(fat, cl)) {
+ pfatal("Invalid cluster: %ud", cl);
+ return CLUST_DEAD;
+ }
+
+ return (fat->get(fat, cl));
+}
+
+int fat_set_cl_next(struct fat_descriptor *fat, cl_t cl, cl_t nextcl)
+{
+
+ if (rdonly) {
+ pwarn(" (NO WRITE)\n");
+ return FSFATAL;
+ }
+
+ if (!valid_cl(fat, cl)) {
+ pfatal("Invalid cluster: %ud", cl);
+ return FSFATAL;
+ }
+
+ return (fat->set(fat, cl, nextcl));
+}
+
+static inline struct bootblock*
+boot_of_(struct fat_descriptor *fat) {
+
+ return (fat->boot);
+}
+
+struct bootblock*
+fat_get_boot(struct fat_descriptor *fat) {
+
+ return (boot_of_(fat));
+}
+
+static inline int
+fd_of_(struct fat_descriptor *fat)
+{
+ return (fat->fd);
+}
+
+int
+fat_get_fd(struct fat_descriptor * fat)
+{
+ return (fd_of_(fat));
+}
+
+/*
+ * Whether a cl is in valid data range.
+ */
+bool
+fat_is_valid_cl(struct fat_descriptor *fat, cl_t cl)
+{
+
+ return (valid_cl(fat, cl));
+}
+
+static inline bool
+valid_cl(struct fat_descriptor *fat, cl_t cl)
+{
+ const struct bootblock *boot = boot_of_(fat);
+
+ return (cl >= CLUST_FIRST && cl < boot->NumClusters);
+}
+
+/*
* The first 2 FAT entries contain pseudo-cluster numbers with the following
* layout:
*
@@ -129,93 +643,178 @@ err:
}
/*
- * Check a cluster number for valid value
+ * Read a FAT from disk. Returns 1 if successful, 0 otherwise.
*/
static int
-checkclnum(struct bootblock *boot, u_int fat, cl_t cl, cl_t *next)
+_readfat(struct fat_descriptor *fat)
{
- if (*next >= (CLUST_RSRVD&boot->ClustMask))
- *next |= ~boot->ClustMask;
- if (*next == CLUST_FREE) {
- boot->NumFree++;
- return FSOK;
- }
- if (*next == CLUST_BAD) {
- boot->NumBad++;
- return FSOK;
- }
- if (*next < CLUST_FIRST
- || (*next >= boot->NumClusters && *next < CLUST_EOFS)) {
- pwarn("Cluster %u in FAT %d continues with %s cluster number %u\n",
- cl, fat,
- *next < CLUST_RSRVD ? "out of range" : "reserved",
- *next&boot->ClustMask);
- if (ask(0, "Truncate")) {
- *next = CLUST_EOF;
- return FSFATMOD;
+ int fd;
+ size_t i;
+ off_t off;
+ size_t readsize;
+ struct bootblock *boot;
+ struct fat32_cache_entry *entry;
+
+ boot = boot_of_(fat);
+ fd = fd_of_(fat);
+ fat->fatsize = boot->FATsecs * boot->bpbBytesPerSec;
+
+ off = boot->bpbResSectors;
+ off *= boot->bpbBytesPerSec;
+
+ fat->is_mmapped = false;
+ fat->use_cache = false;
+
+ /* Attempt to mmap() first */
+ if (allow_mmap) {
+ fat->fatbuf = mmap(NULL, fat->fatsize,
+ PROT_READ | (rdonly ? 0 : PROT_WRITE),
+ MAP_SHARED, fd_of_(fat), off);
+ if (fat->fatbuf != MAP_FAILED) {
+ fat->is_mmapped = true;
+ return 1;
}
- return FSERROR;
}
- return FSOK;
-}
-/*
- * Read a FAT from disk. Returns 1 if successful, 0 otherwise.
- */
-static int
-_readfat(int fs, struct bootblock *boot, u_int no, u_char **buffer)
-{
- off_t off;
+ /*
+ * Unfortunately, we were unable to mmap().
+ *
+ * Only use the cache manager when it's necessary, that is,
+ * when the FAT is sufficiently large; in that case, only
+ * read in the first 4 MiB of FAT into memory, and split the
+ * buffer into chunks and insert to the LRU queue to populate
+ * the cache with data.
+ */
+ if (boot->ClustMask == CLUST32_MASK &&
+ fat->fatsize >= fat32_cache_size) {
+ readsize = fat32_cache_size;
+ fat->use_cache = true;
- *buffer = calloc(boot->FATsecs, boot->bpbBytesPerSec);
- if (*buffer == NULL) {
- perr("No space for FAT sectors (%zu)",
- (size_t)boot->FATsecs);
+ fat->fat32_offset = boot->bpbResSectors * boot->bpbBytesPerSec;
+ fat->fat32_lastaddr = fat->fatsize & ~(fat32_cache_chunk_size);
+ } else {
+ readsize = fat->fatsize;
+ }
+ fat->fatbuf = malloc(readsize);
+ if (fat->fatbuf == NULL) {
+ perr("No space for FAT (%zu)", readsize);
return 0;
}
- off = boot->bpbResSectors + no * boot->FATsecs;
- off *= boot->bpbBytesPerSec;
-
- if (lseek(fs, off, SEEK_SET) != off) {
+ if (lseek(fd, off, SEEK_SET) != off) {
perr("Unable to read FAT");
goto err;
}
-
- if ((size_t)read(fs, *buffer, boot->FATsecs * boot->bpbBytesPerSec)
- != boot->FATsecs * boot->bpbBytesPerSec) {
+ if ((size_t)read(fd, fat->fatbuf, readsize) != readsize) {
perr("Unable to read FAT");
goto err;
}
+ /*
+ * When cache is used, split the buffer into chunks, and
+ * connect the buffer into the cache.
+ */
+ if (fat->use_cache) {
+ TAILQ_INIT(&fat->fat32_cache_head);
+ entry = calloc(fat32_cache_entries, sizeof(*entry));
+ if (entry == NULL) {
+ perr("No space for FAT cache (%zu of %zu)",
+ fat32_cache_entries, sizeof(entry));
+ goto err;
+ }
+ for (i = 0; i < fat32_cache_entries; i++) {
+ entry[i].addr = fat32_cache_chunk_size * i;
+ entry[i].chunk = &fat->fatbuf[entry[i].addr];
+ TAILQ_INSERT_TAIL(&fat->fat32_cache_head,
+ &entry[i], entries);
+ }
+ fat->fat32_cache_allentries = entry;
+ }
+
return 1;
- err:
- free(*buffer);
+err:
+ free(fat->fatbuf);
+ fat->fatbuf = NULL;
return 0;
}
+static void
+releasefat(struct fat_descriptor *fat)
+{
+ if (fat->is_mmapped) {
+ munmap(fat->fatbuf, fat->fatsize);
+ } else {
+ if (fat->use_cache) {
+ free(fat->fat32_cache_allentries);
+ fat->fat32_cache_allentries = NULL;
+ }
+ free(fat->fatbuf);
+ }
+ fat->fatbuf = NULL;
+ bitmap_dtor(&fat->headbitmap);
+}
+
/*
- * Read a FAT and decode it into internal format
+ * Read or map a FAT and populate head bitmap
*/
int
-readfat(int fs, struct bootblock *boot, u_int no, struct fatEntry **fp)
+readfat(int fs, struct bootblock *boot, struct fat_descriptor **fp)
{
- struct fatEntry *fat;
+ struct fat_descriptor *fat;
u_char *buffer, *p;
- cl_t cl;
+ cl_t cl, nextcl;
int ret = FSOK;
boot->NumFree = boot->NumBad = 0;
- if (!_readfat(fs, boot, no, &buffer))
+ fat = calloc(1, sizeof(struct fat_descriptor));
+ if (fat == NULL) {
+ perr("No space for FAT descriptor");
return FSFATAL;
+ }
- fat = calloc(boot->NumClusters, sizeof(struct fatEntry));
- if (fat == NULL) {
- perr("No space for FAT clusters (%zu)",
+ fat->fd = fs;
+ fat->boot = boot;
+
+ if (!_readfat(fat)) {
+ free(fat);
+ return FSFATAL;
+ }
+ buffer = fat->fatbuf;
+
+ /* Populate accessors */
+ switch(boot->ClustMask) {
+ case CLUST12_MASK:
+ fat->get = fat_get_fat12_next;
+ fat->set = fat_set_fat12_next;
+ break;
+ case CLUST16_MASK:
+ fat->get = fat_get_fat16_next;
+ fat->set = fat_set_fat16_next;
+ break;
+ case CLUST32_MASK:
+ if (fat->is_mmapped || !fat->use_cache) {
+ fat->get = fat_get_fat32_next;
+ fat->set = fat_set_fat32_next;
+ } else {
+ fat->get = fat_get_fat32_cached_next;
+ fat->set = fat_set_fat32_cached_next;
+ }
+ break;
+ default:
+ pfatal("Invalid ClustMask: %d", boot->ClustMask);
+ releasefat(fat);
+ free(fat);
+ return FSFATAL;
+ }
+
+ if (bitmap_ctor(&fat->headbitmap, boot->NumClusters,
+ true) != FSOK) {
+ perr("No space for head bitmap for FAT clusters (%zu)",
(size_t)boot->NumClusters);
- free(buffer);
+ releasefat(fat);
+ free(fat);
return FSFATAL;
}
@@ -263,54 +862,106 @@ readfat(int fs, struct bootblock *boot, u_int no, struct fatEntry **fp)
break;
}
+ if (ask(1, "Correct")) {
+ ret |= FSFATMOD;
+ p = buffer;
- if (ask(1, "Correct"))
- ret |= FSFIXFAT;
+ *p++ = (u_char)boot->bpbMedia;
+ *p++ = 0xff;
+ *p++ = 0xff;
+ switch (boot->ClustMask) {
+ case CLUST16_MASK:
+ *p++ = 0xff;
+ break;
+ case CLUST32_MASK:
+ *p++ = 0x0f;
+ *p++ = 0xff;
+ *p++ = 0xff;
+ *p++ = 0xff;
+ *p++ = 0x0f;
+ break;
+ default:
+ break;
+ }
+ }
}
}
- switch (boot->ClustMask) {
- case CLUST32_MASK:
- p = buffer + 8;
- break;
- case CLUST16_MASK:
- p = buffer + 4;
- break;
- default:
- p = buffer + 3;
- break;
- }
- for (cl = CLUST_FIRST; cl < boot->NumClusters;) {
- switch (boot->ClustMask) {
- case CLUST32_MASK:
- fat[cl].next = p[0] + (p[1] << 8)
- + (p[2] << 16) + (p[3] << 24);
- fat[cl].next &= boot->ClustMask;
- ret |= checkclnum(boot, no, cl, &fat[cl].next);
- cl++;
- p += 4;
- break;
- case CLUST16_MASK:
- fat[cl].next = p[0] + (p[1] << 8);
- ret |= checkclnum(boot, no, cl, &fat[cl].next);
- cl++;
- p += 2;
- break;
- default:
- fat[cl].next = (p[0] + (p[1] << 8)) & 0x0fff;
- ret |= checkclnum(boot, no, cl, &fat[cl].next);
- cl++;
- if (cl >= boot->NumClusters)
- break;
- fat[cl].next = ((p[1] >> 4) + (p[2] << 4)) & 0x0fff;
- ret |= checkclnum(boot, no, cl, &fat[cl].next);
- cl++;
- p += 3;
- break;
+
+ /*
+ * Traverse the FAT table and populate head map. Initially, we
+ * consider all clusters as possible head cluster (beginning of
+ * a file or directory), and traverse the whole allocation table
+ * by marking every non-head nodes as such (detailed below) and
+ * fix obvious issues while we walk.
+ *
+ * For each "next" cluster, the possible values are:
+ *
+ * a) CLUST_FREE or CLUST_BAD. The *current* cluster can't be a
+ * head node.
+ * b) An out-of-range value. The only fix would be to truncate at
+ * the cluster.
+ * c) A valid cluster. It means that cluster (nextcl) is not a
+ * head cluster. Note that during the scan, every cluster is
+ * expected to be seen for at most once, and when we saw them
+ * twice, it means a cross-linked chain which should be
+ * truncated at the current cluster.
+ *
+ * After scan, the remaining set bits indicates all possible
+ * head nodes, because they were never claimed by any other
+ * node as the next node, but we do not know if these chains
+ * would end with a valid EOF marker. We will check that in
+ * checkchain() at a later time when checking directories,
+ * where these head nodes would be marked as non-head.
+ *
+ * In the final pass, all head nodes should be cleared, and if
+ * there is still head nodes, these would be leaders of lost
+ * chain.
+ */
+ for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++) {
+ nextcl = fat_get_cl_next(fat, cl);
+
+ /* Check if the next cluster number is valid */
+ if (nextcl == CLUST_FREE) {
+ /* Save a hint for next free cluster */
+ if (boot->FSNext == 0) {
+ boot->FSNext = cl;
+ }
+ if (fat_is_cl_head(fat, cl)) {
+ fat_clear_cl_head(fat, cl);
+ }
+ boot->NumFree++;
+ } else if (nextcl == CLUST_BAD) {
+ if (fat_is_cl_head(fat, cl)) {
+ fat_clear_cl_head(fat, cl);
+ }
+ boot->NumBad++;
+ } else if (!valid_cl(fat, nextcl) && nextcl < CLUST_EOFS) {
+ pwarn("Cluster %u continues with %s "
+ "cluster number %u\n",
+ cl, (nextcl < CLUST_RSRVD) ?
+ "out of range" : "reserved",
+ nextcl & boot->ClustMask);
+ if (ask(0, "Truncate")) {
+ ret |= fat_set_cl_next(fat, cl, CLUST_EOF);
+ ret |= FSFATMOD;
+ }
+ } else if (nextcl < boot->NumClusters) {
+ if (fat_is_cl_head(fat, nextcl)) {
+ fat_clear_cl_head(fat, nextcl);
+ } else {
+ pwarn("Cluster %u crossed another chain at %u\n",
+ cl, nextcl);
+ if (ask(0, "Truncate")) {
+ ret |= fat_set_cl_next(fat, cl, CLUST_EOF);
+ ret |= FSFATMOD;
+ }
+ }
}
+
}
- free(buffer);
if (ret & FSFATAL) {
+ releasefat(fat);
free(fat);
*fp = NULL;
} else
@@ -333,332 +984,202 @@ rsrvdcltype(cl_t cl)
return "bad";
}
-static int
-clustdiffer(cl_t cl, cl_t *cp1, cl_t *cp2, u_int fatnum)
-{
- if (*cp1 == CLUST_FREE || *cp1 >= CLUST_RSRVD) {
- if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
- if ((*cp1 != CLUST_FREE && *cp1 < CLUST_BAD
- && *cp2 != CLUST_FREE && *cp2 < CLUST_BAD)
- || (*cp1 > CLUST_BAD && *cp2 > CLUST_BAD)) {
- pwarn("Cluster %u is marked %s with different indicators\n",
- cl, rsrvdcltype(*cp1));
- if (ask(1, "Fix")) {
- *cp2 = *cp1;
- return FSFATMOD;
- }
- return FSFATAL;
- }
- pwarn("Cluster %u is marked %s in FAT 0, %s in FAT %u\n",
- cl, rsrvdcltype(*cp1), rsrvdcltype(*cp2), fatnum);
- if (ask(0, "Use FAT 0's entry")) {
- *cp2 = *cp1;
- return FSFATMOD;
- }
- if (ask(0, "Use FAT %u's entry", fatnum)) {
- *cp1 = *cp2;
- return FSFATMOD;
- }
- return FSFATAL;
- }
- pwarn("Cluster %u is marked %s in FAT 0, but continues with cluster %u in FAT %d\n",
- cl, rsrvdcltype(*cp1), *cp2, fatnum);
- if (ask(0, "Use continuation from FAT %u", fatnum)) {
- *cp1 = *cp2;
- return FSFATMOD;
- }
- if (ask(0, "Use mark from FAT 0")) {
- *cp2 = *cp1;
- return FSFATMOD;
- }
- return FSFATAL;
- }
- if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
- pwarn("Cluster %u continues with cluster %u in FAT 0, but is marked %s in FAT %u\n",
- cl, *cp1, rsrvdcltype(*cp2), fatnum);
- if (ask(0, "Use continuation from FAT 0")) {
- *cp2 = *cp1;
- return FSFATMOD;
- }
- if (ask(0, "Use mark from FAT %d", fatnum)) {
- *cp1 = *cp2;
- return FSFATMOD;
- }
+/*
+ * Offer to truncate a chain at the specified CL, called by checkchain().
+ */
+static inline int
+truncate_at(struct fat_descriptor *fat, cl_t current_cl, size_t *chainsize)
+{
+ int ret = 0;
+
+ if (ask(0, "Truncate")) {
+ ret = fat_set_cl_next(fat, current_cl, CLUST_EOF);
+ (*chainsize)++;
+ return (ret | FSFATMOD);
+ } else {
return FSERROR;
}
- pwarn("Cluster %u continues with cluster %u in FAT 0, but with cluster %u in FAT %u\n",
- cl, *cp1, *cp2, fatnum);
- if (ask(0, "Use continuation from FAT 0")) {
- *cp2 = *cp1;
- return FSFATMOD;
- }
- if (ask(0, "Use continuation from FAT %u", fatnum)) {
- *cp1 = *cp2;
- return FSFATMOD;
- }
- return FSERROR;
}
/*
- * Compare two FAT copies in memory. Resolve any conflicts and merge them
- * into the first one.
+ * Examine a cluster chain for errors and count its size.
*/
int
-comparefat(struct bootblock *boot, struct fatEntry *first,
- struct fatEntry *second, u_int fatnum)
+checkchain(struct fat_descriptor *fat, cl_t head, size_t *chainsize)
{
- cl_t cl;
- int ret = FSOK;
+ cl_t current_cl, next_cl;
- for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++)
- if (first[cl].next != second[cl].next)
- ret |= clustdiffer(cl, &first[cl].next, &second[cl].next, fatnum);
- return ret;
+ /*
+ * We expect that the caller to give us a real, unvisited 'head'
+ * cluster, and it must be a valid cluster. While scanning the
+ * FAT table, we already excluded all clusters that was claimed
+ * as a "next" cluster. Assert all the three conditions.
+ */
+ assert(valid_cl(fat, head));
+ assert(fat_is_cl_head(fat, head));
+
+ /*
+ * Immediately mark the 'head' cluster that we are about to visit.
+ */
+ fat_clear_cl_head(fat, head);
+
+ /*
+ * The allocation of a non-zero sized file or directory is
+ * represented as a singly linked list, and the tail node
+ * would be the EOF marker (>=CLUST_EOFS).
+ *
+ * With a valid head node at hand, we expect all subsequent
+ * cluster to be either a not yet seen and valid cluster (we
+ * would continue counting), or the EOF marker (we conclude
+ * the scan of this chain).
+ *
+ * For all other cases, the chain is invalid, and the only
+ * viable fix would be to truncate at the current node (mark
+ * it as EOF) when the next node violates that.
+ */
+ *chainsize = 0;
+ current_cl = head;
+ for (next_cl = fat_get_cl_next(fat, current_cl);
+ valid_cl(fat, next_cl);
+ current_cl = next_cl, next_cl = fat_get_cl_next(fat, current_cl))
+ (*chainsize)++;
+
+ /* A natural end */
+ if (next_cl >= CLUST_EOFS) {
+ (*chainsize)++;
+ return FSOK;
+ }
+
+ /* The chain ended with an out-of-range cluster number. */
+ pwarn("Cluster %u continues with %s cluster number %u\n",
+ current_cl,
+ next_cl < CLUST_RSRVD ? "out of range" : "reserved",
+ next_cl & boot_of_(fat)->ClustMask);
+ return (truncate_at(fat, current_cl, chainsize));
}
+/*
+ * Clear cluster chain from head.
+ */
void
-clearchain(struct bootblock *boot, struct fatEntry *fat, cl_t head)
+clearchain(struct fat_descriptor *fat, cl_t head)
{
- cl_t p, q;
+ cl_t current_cl, next_cl;
+ struct bootblock *boot = boot_of_(fat);
+
+ current_cl = head;
- for (p = head; p >= CLUST_FIRST && p < boot->NumClusters; p = q) {
- if (fat[p].head != head)
- break;
- q = fat[p].next;
- fat[p].next = fat[p].head = CLUST_FREE;
- fat[p].length = 0;
+ while (valid_cl(fat, current_cl)) {
+ next_cl = fat_get_cl_next(fat, head);
+ (void)fat_set_cl_next(fat, current_cl, CLUST_FREE);
+ boot->NumFree++;
+ current_cl = next_cl;
}
-}
-int
-tryclear(struct bootblock *boot, struct fatEntry *fat, cl_t head, cl_t *truncp)
-{
- if (ask(0, "Clear chain starting at %u", head)) {
- clearchain(boot, fat, head);
- return FSFATMOD;
- } else if (ask(0, "Truncate")) {
- uint32_t len;
- cl_t p;
-
- for (p = head, len = 0;
- p >= CLUST_FIRST && p < boot->NumClusters;
- p = fat[p].next, len++)
- continue;
- *truncp = CLUST_EOF;
- fat[head].length = len;
- return FSFATMOD;
- } else
- return FSERROR;
}
/*
- * Check a complete FAT in-memory for crosslinks
+ * Overwrite the n-th FAT with FAT0
*/
-int
-checkfat(struct bootblock *boot, struct fatEntry *fat)
+static int
+copyfat(struct fat_descriptor *fat, int n)
{
- cl_t head, p, h, n;
- u_int len;
- int ret = 0;
- int conf;
+ size_t rwsize, tailsize, blobs, i;
+ off_t dst_off, src_off;
+ struct bootblock *boot;
+ int ret, fd;
- /*
- * pass 1: figure out the cluster chains.
- */
- for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
- /* find next untravelled chain */
- if (fat[head].head != 0 /* cluster already belongs to some chain */
- || fat[head].next == CLUST_FREE
- || fat[head].next == CLUST_BAD)
- continue; /* skip it. */
-
- /* follow the chain and mark all clusters on the way */
- for (len = 0, p = head;
- p >= CLUST_FIRST && p < boot->NumClusters &&
- fat[p].head != head;
- p = fat[p].next) {
- fat[p].head = head;
- len++;
- }
+ ret = FSOK;
+ fd = fd_of_(fat);
+ boot = boot_of_(fat);
- /* the head record gets the length */
- fat[head].length = fat[head].next == CLUST_FREE ? 0 : len;
+ blobs = howmany(fat->fatsize, fat32_cache_size);
+ tailsize = fat->fatsize % fat32_cache_size;
+ if (tailsize == 0) {
+ tailsize = fat32_cache_size;
}
+ rwsize = fat32_cache_size;
- /*
- * pass 2: check for crosslinked chains (we couldn't do this in pass 1 because
- * we didn't know the real start of the chain then - would have treated partial
- * chains as interlinked with their main chain)
- */
- for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
- /* find next untravelled chain */
- if (fat[head].head != head)
- continue;
+ src_off = fat->fat32_offset;
+ dst_off = boot->bpbResSectors + n * boot->FATsecs;
+ dst_off *= boot->bpbBytesPerSec;
- /* follow the chain to its end (hopefully) */
- for (len = fat[head].length, p = head;
- (n = fat[p].next) >= CLUST_FIRST && n < boot->NumClusters;
- p = n)
- if (fat[n].head != head || len-- < 2)
- break;
- if (n >= CLUST_EOFS)
- continue;
-
- if (n == CLUST_FREE || n >= CLUST_RSRVD) {
- pwarn("Cluster chain starting at %u ends with cluster marked %s\n",
- head, rsrvdcltype(n));
-clear:
- ret |= tryclear(boot, fat, head, &fat[p].next);
- continue;
+ for (i = 0; i < blobs;
+ i++, src_off += fat32_cache_size, dst_off += fat32_cache_size) {
+ if (i == blobs - 1) {
+ rwsize = tailsize;
}
- if (n < CLUST_FIRST || n >= boot->NumClusters) {
- pwarn("Cluster chain starting at %u ends with cluster out of range (%u)\n",
- head, n);
- goto clear;
- }
- if (head == fat[n].head) {
- pwarn("Cluster chain starting at %u loops at cluster %u\n",
- head, p);
- goto clear;
+ if ((lseek(fd, src_off, SEEK_SET) != src_off ||
+ (size_t)read(fd, fat->fatbuf, rwsize) != rwsize) &&
+ ret == FSOK) {
+ perr("Unable to read FAT0");
+ ret = FSFATAL;
+ continue;
}
- pwarn("Cluster chains starting at %u and %u are linked at cluster %u\n",
- head, fat[n].head, n);
- conf = tryclear(boot, fat, head, &fat[p].next);
- if (ask(0, "Clear chain starting at %u", h = fat[n].head)) {
- if (conf == FSERROR) {
- /*
- * Transfer the common chain to the one not cleared above.
- */
- for (p = n;
- p >= CLUST_FIRST && p < boot->NumClusters;
- p = fat[p].next) {
- if (h != fat[p].head) {
- /*
- * Have to reexamine this chain.
- */
- head--;
- break;
- }
- fat[p].head = head;
- }
- }
- clearchain(boot, fat, h);
- conf |= FSFATMOD;
+ if ((lseek(fd, dst_off, SEEK_SET) != dst_off ||
+ (size_t)write(fd, fat->fatbuf, rwsize) != rwsize) &&
+ ret == FSOK) {
+ perr("Unable to write FAT %d", n);
+ ret = FSERROR;
}
- ret |= conf;
}
-
- return ret;
+ return (ret);
}
/*
- * Write out FATs encoding them from the internal format
+ * Write out FAT
*/
int
-writefat(int fs, struct bootblock *boot, struct fatEntry *fat, int correct_fat)
+writefat(struct fat_descriptor *fat)
{
- u_char *buffer, *p;
- cl_t cl;
u_int i;
- size_t fatsz;
- off_t off;
- int ret = FSOK;
+ size_t writesz;
+ off_t dst_base;
+ int ret = FSOK, fd;
+ struct bootblock *boot;
+ struct fat32_cache_entry *entry;
- fatsz = boot->FATsecs * boot->bpbBytesPerSec;
- buffer = calloc(boot->FATsecs, boot->bpbBytesPerSec);
- if (buffer == NULL) {
- perr("No space for FAT sectors (%zu)",
- (size_t)boot->FATsecs);
- return FSFATAL;
- }
- boot->NumFree = 0;
- p = buffer;
- if (correct_fat) {
- *p++ = (u_char)boot->bpbMedia;
- *p++ = 0xff;
- *p++ = 0xff;
- switch (boot->ClustMask) {
- case CLUST16_MASK:
- *p++ = 0xff;
- break;
- case CLUST32_MASK:
- *p++ = 0x0f;
- *p++ = 0xff;
- *p++ = 0xff;
- *p++ = 0xff;
- *p++ = 0x0f;
- break;
- }
- } else {
- /* use same FAT signature as the old FAT has */
- int count;
- u_char *old_fat;
-
- switch (boot->ClustMask) {
- case CLUST32_MASK:
- count = 8;
- break;
- case CLUST16_MASK:
- count = 4;
- break;
- default:
- count = 3;
- break;
- }
+ boot = boot_of_(fat);
+ fd = fd_of_(fat);
- if (!_readfat(fs, boot, boot->ValidFat >= 0 ? boot->ValidFat :0,
- &old_fat)) {
- free(buffer);
- return FSFATAL;
+ if (fat->use_cache) {
+ /*
+ * Attempt to flush all in-flight cache, and bail out
+ * if we encountered an error (but only emit error
+ * message once). Stop proceeding with copyfat()
+ * if any flush failed.
+ */
+ TAILQ_FOREACH(entry, &fat->fat32_cache_head, entries) {
+ if (fat_flush_fat32_cache_entry(fat, entry) != FSOK) {
+ if (ret == FSOK) {
+ perr("Unable to write FAT");
+ ret = FSFATAL;
+ }
+ }
}
+ if (ret != FSOK)
+ return (ret);
- memcpy(p, old_fat, count);
- free(old_fat);
- p += count;
- }
-
- for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++) {
- switch (boot->ClustMask) {
- case CLUST32_MASK:
- if (fat[cl].next == CLUST_FREE)
- boot->NumFree++;
- *p++ = (u_char)fat[cl].next;
- *p++ = (u_char)(fat[cl].next >> 8);
- *p++ = (u_char)(fat[cl].next >> 16);
- *p &= 0xf0;
- *p++ |= (fat[cl].next >> 24)&0x0f;
- break;
- case CLUST16_MASK:
- if (fat[cl].next == CLUST_FREE)
- boot->NumFree++;
- *p++ = (u_char)fat[cl].next;
- *p++ = (u_char)(fat[cl].next >> 8);
- break;
- default:
- if (fat[cl].next == CLUST_FREE)
- boot->NumFree++;
- *p++ = (u_char)fat[cl].next;
- *p = (u_char)((fat[cl].next >> 8) & 0xf);
- cl++;
- if (cl >= boot->NumClusters)
- break;
- if (fat[cl].next == CLUST_FREE)
- boot->NumFree++;
- *p++ |= (u_char)(fat[cl].next << 4);
- *p++ = (u_char)(fat[cl].next >> 4);
- break;
+ /* Update backup copies of FAT, error is not fatal */
+ for (i = 1; i < boot->bpbFATs; i++) {
+ if (copyfat(fat, i) != FSOK)
+ ret = FSERROR;
}
- }
- for (i = 0; i < boot->bpbFATs; i++) {
- off = boot->bpbResSectors + i * boot->FATsecs;
- off *= boot->bpbBytesPerSec;
- if (lseek(fs, off, SEEK_SET) != off
- || (size_t)write(fs, buffer, fatsz) != fatsz) {
- perr("Unable to write FAT");
- ret = FSFATAL; /* Return immediately? XXX */
+ } else {
+ writesz = fat->fatsize;
+
+ for (i = fat->is_mmapped ? 1 : 0; i < boot->bpbFATs; i++) {
+ dst_base = boot->bpbResSectors + i * boot->FATsecs;
+ dst_base *= boot->bpbBytesPerSec;
+ if ((lseek(fd, dst_base, SEEK_SET) != dst_base ||
+ (size_t)write(fd, fat->fatbuf, writesz) != writesz) &&
+ ret == FSOK) {
+ perr("Unable to write FAT %d", i);
+ ret = ((i == 0) ? FSFATAL : FSERROR);
+ }
}
}
- free(buffer);
+
return ret;
}
@@ -666,31 +1187,55 @@ writefat(int fs, struct bootblock *boot, struct fatEntry *fat, int correct_fat)
* Check a complete in-memory FAT for lost cluster chains
*/
int
-checklost(int dosfs, struct bootblock *boot, struct fatEntry *fat)
+checklost(struct fat_descriptor *fat)
{
cl_t head;
int mod = FSOK;
- int ret;
-
- for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
- /* find next untravelled chain */
- if (fat[head].head != head
- || fat[head].next == CLUST_FREE
- || (fat[head].next >= CLUST_RSRVD
- && fat[head].next < CLUST_EOFS)
- || (fat[head].flags & FAT_USED))
- continue;
+ int dosfs, ret;
+ size_t chains, chainlength;
+ struct bootblock *boot;
+
+ dosfs = fd_of_(fat);
+ boot = boot_of_(fat);
- pwarn("Lost cluster chain at cluster %u\n%d Cluster(s) lost\n",
- head, fat[head].length);
- mod |= ret = reconnect(dosfs, boot, fat, head);
- if (mod & FSFATAL)
- break;
- if (ret == FSERROR && ask(0, "Clear")) {
- clearchain(boot, fat, head);
- mod |= FSFATMOD;
+ /*
+ * At this point, we have already traversed all directories.
+ * All remaining chain heads in the bitmap are heads of lost
+ * chains.
+ */
+ chains = fat_get_head_count(fat);
+ for (head = CLUST_FIRST;
+ chains > 0 && head < boot->NumClusters;
+ ) {
+ /*
+ * We expect the bitmap to be very sparse, so skip if
+ * the range is full of 0's
+ */
+ if (head % LONG_BIT == 0 &&
+ !fat_is_cl_head_in_range(fat, head)) {
+ head += LONG_BIT;
+ continue;
+ }
+ if (fat_is_cl_head(fat, head)) {
+ ret = checkchain(fat, head, &chainlength);
+ if (ret != FSERROR) {
+ pwarn("Lost cluster chain at cluster %u\n"
+ "%zd Cluster(s) lost\n",
+ head, chainlength);
+ mod |= ret = reconnect(fat, head,
+ chainlength);
+ }
+ if (mod & FSFATAL)
+ break;
+ if (ret == FSERROR && ask(0, "Clear")) {
+ clearchain(fat, head);
+ mod |= FSFATMOD;
+ }
+ chains--;
}
+ head++;
}
+
finishlf();
if (boot->bpbFSInfo) {
@@ -706,13 +1251,13 @@ checklost(int dosfs, struct bootblock *boot, struct fatEntry *fat)
}
if (boot->FSNext != 0xffffffffU &&
(boot->FSNext >= boot->NumClusters ||
- (boot->NumFree && fat[boot->FSNext].next != CLUST_FREE))) {
+ (boot->NumFree && fat_get_cl_next(fat, boot->FSNext) != CLUST_FREE))) {
pwarn("Next free cluster in FSInfo block (%u) %s\n",
boot->FSNext,
(boot->FSNext >= boot->NumClusters) ? "invalid" : "not free");
- if (ask(1, "fix"))
+ if (ask(1, "Fix"))
for (head = CLUST_FIRST; head < boot->NumClusters; head++)
- if (fat[head].next == CLUST_FREE) {
+ if (fat_get_cl_next(fat, head) == CLUST_FREE) {
boot->FSNext = head;
ret = 1;
break;
diff --git a/sbin/fsck_msdosfs/main.c b/sbin/fsck_msdosfs/main.c
index 6802afcefc46..de54cd18eae7 100644
--- a/sbin/fsck_msdosfs/main.c
+++ b/sbin/fsck_msdosfs/main.c
@@ -48,6 +48,7 @@ int alwaysyes; /* assume "yes" for all questions */
int preen; /* set when preening */
int rdonly; /* device is opened read only (supersedes above) */
int skipclean; /* skip clean file systems if preening */
+int allow_mmap; /* Allow the use of mmap(), if possible */
static void usage(void) __dead2;
@@ -68,7 +69,8 @@ main(int argc, char **argv)
int ch;
skipclean = 1;
- while ((ch = getopt(argc, argv, "CfFnpy")) != -1) {
+ allow_mmap = 1;
+ while ((ch = getopt(argc, argv, "CfFnpyM")) != -1) {
switch (ch) {
case 'C': /* for fsck_ffs compatibility */
break;
@@ -98,6 +100,10 @@ main(int argc, char **argv)
preen = 1;
break;
+ case 'M':
+ allow_mmap = 0;
+ break;
+
default:
usage();
break;