Welcome back our old friend from procfs, "file"!

3 files changed, 155 insertions, 19 deletions

diff --git a/sys/fs/procfs/procfs.h b/sys/fs/procfs/procfs.h
index f0000267b5d7..ebeea31534c0 100644
--- a/sys/fs/procfs/procfs.h
+++ b/sys/fs/procfs/procfs.h
@@ -140,6 +140,7 @@ int procfs_domap __P((struct proc *, struct proc *, struct pfsnode *pfsp, struct
 int procfs_dotype __P((struct proc *, struct proc *, struct pfsnode *pfsp, struct uio *uio));
 int procfs_docmdline __P((struct proc *, struct proc *, struct pfsnode *pfsp, struct uio *uio));
 int procfs_dorlimit __P((struct proc *, struct proc *, struct pfsnode *pfsp, struct uio *uio));
+int procfs_fullpath __P((struct proc *p, char **retbuf, char **retfreebuf));
 
 /* Return 1 if process has special kernel digging privileges */
 int procfs_kmemaccess __P((struct proc *));
diff --git a/sys/fs/procfs/procfs_subr.c b/sys/fs/procfs/procfs_subr.c
index 01e8ae9e014a..a7bbfd716075 100644
--- a/sys/fs/procfs/procfs_subr.c
+++ b/sys/fs/procfs/procfs_subr.c
@@ -41,9 +41,13 @@
 
 #include <sys/param.h>
 #include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/sysctl.h>
 #include <sys/proc.h>
+#include <sys/mount.h>
 #include <sys/vnode.h>
 #include <sys/malloc.h>
+
 #include <miscfs/procfs/procfs.h>
 
 static struct pfsnode *pfshead;
@@ -159,6 +163,10 @@ loop:
 		break;
 
 	case Pfile:
+		pfs->pfs_mode = (VREAD|VEXEC);
+		vp->v_type = VLNK;
+		break;
+
 	case Pmem:
 		pfs->pfs_mode = (VREAD|VWRITE) |
 				(VREAD) >> 3;;
@@ -400,3 +408,99 @@ procfs_exit(struct proc *p)
 			pfs = pfs->pfs_next;
 	}
 }
+
+/*
+ * Thus begins the fullpath magic.
+ */
+
+SYSCTL_DECL(_vfs_cache);
+
+#define STATNODE(name)							\
+	static u_int name;						\
+	SYSCTL_INT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "")
+
+static int disablefullpath;
+SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW,
+    &disablefullpath, 0, "");
+
+STATNODE(numfullpathcalls);
+STATNODE(numfullpathfail1);
+STATNODE(numfullpathfail2);
+STATNODE(numfullpathfail3);
+STATNODE(numfullpathfail4);
+STATNODE(numfullpathfound);
+
+int
+procfs_fullpath(struct proc *p, char **retbuf, char **retfreebuf) {
+	char *bp, *buf;
+	int i, slash_prefixed;
+	struct filedesc *fdp;
+	struct namecache *ncp;
+	struct vnode *vp, *textvp;
+
+	numfullpathcalls++;
+	if (disablefullpath)
+		return (ENODEV);
+	textvp = p->p_textvp;
+	if (textvp == NULL)
+		return (EINVAL);
+	buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
+	bp = buf + MAXPATHLEN - 1;
+	*bp = '\0';
+	fdp = p->p_fd;
+	slash_prefixed = 0;
+	for (vp = textvp; vp != fdp->fd_rdir && vp != rootvnode;) {
+		if (vp->v_flag & VROOT) {
+			if (vp->v_mount == NULL) {	/* forced unmount */
+				free(buf, M_TEMP);
+				return (EBADF);
+			}
+			vp = vp->v_mount->mnt_vnodecovered;
+			continue;
+		}
+		if (vp != textvp && vp->v_dd->v_id != vp->v_ddid) {
+			numfullpathfail1++;
+			free(buf, M_TEMP);
+			return (ENOTDIR);
+		}
+		ncp = TAILQ_FIRST(&vp->v_cache_dst);
+		if (!ncp) {
+			numfullpathfail2++;
+			free(buf, M_TEMP);
+			return (ENOENT);
+		}
+		if (vp != textvp && ncp->nc_dvp != vp->v_dd) {
+			numfullpathfail3++;
+			free(buf, M_TEMP);
+			return (EBADF);
+		}
+		for (i = ncp->nc_nlen - 1; i >= 0; i--) {
+			if (bp == buf) {
+				numfullpathfail4++;
+				free(buf, M_TEMP);
+				return (ENOMEM);
+			}
+			*--bp = ncp->nc_name[i];
+		}
+		if (bp == buf) {
+			numfullpathfail4++;
+			free(buf, M_TEMP);
+			return (ENOMEM);
+		}
+		*--bp = '/';
+		slash_prefixed = 1;
+		vp = ncp->nc_dvp;
+	}
+	if (!slash_prefixed) {
+		if (bp == buf) {
+			numfullpathfail4++;
+			free(buf, M_TEMP);
+			return (ENOMEM);
+		}
+		*--bp = '/';
+	}
+	numfullpathfound++;
+	*retbuf = bp; 
+	*retfreebuf = buf;
+	return (0);
+}
diff --git a/sys/fs/procfs/procfs_vnops.c b/sys/fs/procfs/procfs_vnops.c
index d7de7ce230f8..a38fe8191b83 100644
--- a/sys/fs/procfs/procfs_vnops.c
+++ b/sys/fs/procfs/procfs_vnops.c
@@ -52,9 +52,11 @@
 #include <sys/proc.h>
 #include <sys/signalvar.h>
 #include <sys/vnode.h>
+#include <sys/uio.h>
 #include <sys/mount.h>
 #include <sys/namei.h>
 #include <sys/dirent.h>
+#include <sys/malloc.h>
 #include <machine/reg.h>
 #include <vm/vm_zone.h>
 #include <miscfs/procfs/procfs.h>
@@ -103,6 +105,7 @@ static struct proc_target {
 	{ DT_REG, N("etype"),	Ptype,		procfs_validtype },
 	{ DT_REG, N("cmdline"),	Pcmdline,	NULL },
 	{ DT_REG, N("rlimit"),	Prlimit,	NULL },
+	{ DT_LNK, N("file"),	Pfile,		NULL },
 #undef N
 };
 static const int nproc_targets = sizeof(proc_targets) / sizeof(proc_targets[0]);
@@ -529,9 +532,19 @@ procfs_getattr(ap)
 		vap->va_size = vap->va_bytes = DEV_BSIZE;
 		break;
 
-	case Pfile:
-		error = EOPNOTSUPP;
+	case Pfile: {
+		char *fullpath, *freepath;
+		error = procfs_fullpath(procp, &fullpath, &freepath);
+		if (error == 0) {
+			vap->va_size = strlen(fullpath);
+			free(freepath, M_TEMP);
+		} else {
+			vap->va_size = sizeof("unknown") - 1;
+			error = 0;
+		}
+		vap->va_bytes = vap->va_size;
 		break;
+	}
 
 	case Pmem:
 		/*
@@ -686,7 +699,6 @@ procfs_lookup(ap)
 	char *pname = cnp->cn_nameptr;
 	struct proc *curp = cnp->cn_proc;
 	struct proc_target *pt;
-	struct vnode *fvp;
 	pid_t pid;
 	struct pfsnode *pfs;
 	struct proc *p;
@@ -738,17 +750,7 @@ procfs_lookup(ap)
 				goto found;
 		}
 		break;
-
 	found:
-		if (pt->pt_pfstype == Pfile) {
-			fvp = procfs_findtextvp(p);
-			/* We already checked that it exists. */
-			VREF(fvp);
-			vn_lock(fvp, LK_EXCLUSIVE | LK_RETRY, curp);
-			*vpp = fvp;
-			return (0);
-		}
-
 		return (procfs_allocvp(dvp->v_mount, vpp, pfs->pfs_pid,
 		    pt->pt_pfstype));
 
@@ -932,21 +934,50 @@ procfs_readdir(ap)
 }
 
 /*
- * readlink reads the link of `curproc'
+ * readlink reads the link of `curproc' or `file'
  */
 static int
 procfs_readlink(ap)
 	struct vop_readlink_args *ap;
 {
 	char buf[16];		/* should be enough */
-	int len;
+	struct proc *procp;
+	struct vnode *vp = ap->a_vp;
+	struct pfsnode *pfs = VTOPFS(vp);
+	char *fullpath, *freepath;
+	int error, len;
 
-	if (VTOPFS(ap->a_vp)->pfs_fileno != PROCFS_FILENO(0, Pcurproc))
-		return (EINVAL);
+	switch (pfs->pfs_type) {
+	case Pcurproc:
+		if (pfs->pfs_fileno != PROCFS_FILENO(0, Pcurproc))
+			return (EINVAL);
 
-	len = snprintf(buf, sizeof(buf), "%ld", (long)curproc->p_pid);
+		len = snprintf(buf, sizeof(buf), "%ld", (long)curproc->p_pid);
 
-	return (uiomove((caddr_t)buf, len, ap->a_uio));
+		return (uiomove(buf, len, ap->a_uio));
+	/*
+	 * There _should_ be no way for an entire process to disappear
+	 * from under us...
+	 */
+	case Pfile:
+		procp = PFIND(pfs->pfs_pid);
+		if (procp == NULL || procp->p_cred == NULL ||
+		    procp->p_ucred == NULL) {
+			printf("procfs_readlink: pid %d disappeared\n",
+			    pfs->pfs_pid);
+			return (uiomove("unknown", sizeof("unknown") - 1,
+			    ap->a_uio));
+		}
+		error = procfs_fullpath(procp, &fullpath, &freepath);
+		if (error != 0)
+			return (uiomove("unknown", sizeof("unknown") - 1,
+			    ap->a_uio));
+		error = uiomove(fullpath, strlen(fullpath), ap->a_uio);
+		free(freepath, M_TEMP);
+		return (error);
+	default:
+		return (EINVAL);
+	}
 }
 
 /*