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-rw-r--r--sys/contrib/libsodium/src/libsodium/sodium/utils.c733
1 files changed, 733 insertions, 0 deletions
diff --git a/sys/contrib/libsodium/src/libsodium/sodium/utils.c b/sys/contrib/libsodium/src/libsodium/sodium/utils.c
new file mode 100644
index 000000000000..3a5f835b9f0d
--- /dev/null
+++ b/sys/contrib/libsodium/src/libsodium/sodium/utils.c
@@ -0,0 +1,733 @@
+#ifndef __STDC_WANT_LIB_EXT1__
+# define __STDC_WANT_LIB_EXT1__ 1
+#endif
+#include <assert.h>
+#include <errno.h>
+#include <limits.h>
+#include <signal.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef HAVE_SYS_MMAN_H
+# include <sys/mman.h>
+#endif
+
+#ifdef _WIN32
+# include <windows.h>
+# include <wincrypt.h>
+#else
+# include <unistd.h>
+#endif
+
+#ifndef HAVE_C_VARARRAYS
+# ifdef HAVE_ALLOCA_H
+# include <alloca.h>
+# elif !defined(alloca)
+# if defined(__clang__) || defined(__GNUC__)
+# define alloca __builtin_alloca
+# elif defined _AIX
+# define alloca __alloca
+# elif defined _MSC_VER
+# include <malloc.h>
+# define alloca _alloca
+# else
+# include <stddef.h>
+# ifdef __cplusplus
+extern "C"
+# endif
+void *alloca (size_t);
+# endif
+# endif
+#endif
+
+#include "core.h"
+#include "randombytes.h"
+#include "utils.h"
+
+#ifndef ENOSYS
+# define ENOSYS ENXIO
+#endif
+
+#if defined(_WIN32) && \
+ (!defined(WINAPI_FAMILY) || WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP)
+# define WINAPI_DESKTOP
+#endif
+
+#define CANARY_SIZE 16U
+#define GARBAGE_VALUE 0xdb
+
+#ifndef MAP_NOCORE
+# define MAP_NOCORE 0
+#endif
+#if !defined(MAP_ANON) && defined(MAP_ANONYMOUS)
+# define MAP_ANON MAP_ANONYMOUS
+#endif
+#if defined(WINAPI_DESKTOP) || (defined(MAP_ANON) && defined(HAVE_MMAP)) || \
+ defined(HAVE_POSIX_MEMALIGN)
+# define HAVE_ALIGNED_MALLOC
+#endif
+#if defined(HAVE_MPROTECT) && \
+ !(defined(PROT_NONE) && defined(PROT_READ) && defined(PROT_WRITE))
+# undef HAVE_MPROTECT
+#endif
+#if defined(HAVE_ALIGNED_MALLOC) && \
+ (defined(WINAPI_DESKTOP) || defined(HAVE_MPROTECT))
+# define HAVE_PAGE_PROTECTION
+#endif
+#if !defined(MADV_DODUMP) && defined(MADV_CORE)
+# define MADV_DODUMP MADV_CORE
+# define MADV_DONTDUMP MADV_NOCORE
+#endif
+
+static size_t page_size;
+static unsigned char canary[CANARY_SIZE];
+
+/* LCOV_EXCL_START */
+#ifdef HAVE_WEAK_SYMBOLS
+__attribute__((weak)) void
+_sodium_dummy_symbol_to_prevent_memzero_lto(void *const pnt,
+ const size_t len);
+__attribute__((weak)) void
+_sodium_dummy_symbol_to_prevent_memzero_lto(void *const pnt,
+ const size_t len)
+{
+ (void) pnt; /* LCOV_EXCL_LINE */
+ (void) len; /* LCOV_EXCL_LINE */
+}
+#endif
+/* LCOV_EXCL_STOP */
+
+void
+sodium_memzero(void *const pnt, const size_t len)
+{
+#ifdef _WIN32
+ SecureZeroMemory(pnt, len);
+#elif defined(HAVE_MEMSET_S)
+ if (len > 0U && memset_s(pnt, (rsize_t) len, 0, (rsize_t) len) != 0) {
+ sodium_misuse(); /* LCOV_EXCL_LINE */
+ }
+#elif defined(HAVE_EXPLICIT_BZERO)
+ explicit_bzero(pnt, len);
+#elif HAVE_WEAK_SYMBOLS
+ memset(pnt, 0, len);
+ _sodium_dummy_symbol_to_prevent_memzero_lto(pnt, len);
+# ifdef HAVE_INLINE_ASM
+ __asm__ __volatile__ ("" : : "r"(pnt) : "memory");
+# endif
+#else
+ volatile unsigned char *volatile pnt_ =
+ (volatile unsigned char *volatile) pnt;
+ size_t i = (size_t) 0U;
+
+ while (i < len) {
+ pnt_[i++] = 0U;
+ }
+#endif
+}
+
+void
+sodium_stackzero(const size_t len)
+{
+#ifdef HAVE_C_VARARRAYS
+ unsigned char fodder[len];
+ sodium_memzero(fodder, len);
+#elif HAVE_ALLOCA
+ sodium_memzero(alloca(len), len);
+#endif
+}
+
+#ifdef HAVE_WEAK_SYMBOLS
+__attribute__((weak)) void
+_sodium_dummy_symbol_to_prevent_memcmp_lto(const unsigned char *b1,
+ const unsigned char *b2,
+ const size_t len);
+__attribute__((weak)) void
+_sodium_dummy_symbol_to_prevent_memcmp_lto(const unsigned char *b1,
+ const unsigned char *b2,
+ const size_t len)
+{
+ (void) b1;
+ (void) b2;
+ (void) len;
+}
+#endif
+
+int
+sodium_memcmp(const void *const b1_, const void *const b2_, size_t len)
+{
+#ifdef HAVE_WEAK_SYMBOLS
+ const unsigned char *b1 = (const unsigned char *) b1_;
+ const unsigned char *b2 = (const unsigned char *) b2_;
+#else
+ const volatile unsigned char *volatile b1 =
+ (const volatile unsigned char *volatile) b1_;
+ const volatile unsigned char *volatile b2 =
+ (const volatile unsigned char *volatile) b2_;
+#endif
+ size_t i;
+ volatile unsigned char d = 0U;
+
+#if HAVE_WEAK_SYMBOLS
+ _sodium_dummy_symbol_to_prevent_memcmp_lto(b1, b2, len);
+#endif
+ for (i = 0U; i < len; i++) {
+ d |= b1[i] ^ b2[i];
+ }
+ return (1 & ((d - 1) >> 8)) - 1;
+}
+
+#ifdef HAVE_WEAK_SYMBOLS
+__attribute__((weak)) void
+_sodium_dummy_symbol_to_prevent_compare_lto(const unsigned char *b1,
+ const unsigned char *b2,
+ const size_t len);
+__attribute__((weak)) void
+_sodium_dummy_symbol_to_prevent_compare_lto(const unsigned char *b1,
+ const unsigned char *b2,
+ const size_t len)
+{
+ (void) b1;
+ (void) b2;
+ (void) len;
+}
+#endif
+
+int
+sodium_compare(const unsigned char *b1_, const unsigned char *b2_, size_t len)
+{
+#ifdef HAVE_WEAK_SYMBOLS
+ const unsigned char *b1 = b1_;
+ const unsigned char *b2 = b2_;
+#else
+ const volatile unsigned char *volatile b1 =
+ (const volatile unsigned char *volatile) b1_;
+ const volatile unsigned char *volatile b2 =
+ (const volatile unsigned char *volatile) b2_;
+#endif
+ size_t i;
+ volatile unsigned char gt = 0U;
+ volatile unsigned char eq = 1U;
+ uint16_t x1, x2;
+
+#if HAVE_WEAK_SYMBOLS
+ _sodium_dummy_symbol_to_prevent_compare_lto(b1, b2, len);
+#endif
+ i = len;
+ while (i != 0U) {
+ i--;
+ x1 = b1[i];
+ x2 = b2[i];
+ gt |= ((x2 - x1) >> 8) & eq;
+ eq &= ((x2 ^ x1) - 1) >> 8;
+ }
+ return (int) (gt + gt + eq) - 1;
+}
+
+int
+sodium_is_zero(const unsigned char *n, const size_t nlen)
+{
+ size_t i;
+ volatile unsigned char d = 0U;
+
+ for (i = 0U; i < nlen; i++) {
+ d |= n[i];
+ }
+ return 1 & ((d - 1) >> 8);
+}
+
+void
+sodium_increment(unsigned char *n, const size_t nlen)
+{
+ size_t i = 0U;
+ uint_fast16_t c = 1U;
+
+#ifdef HAVE_AMD64_ASM
+ uint64_t t64, t64_2;
+ uint32_t t32;
+
+ if (nlen == 12U) {
+ __asm__ __volatile__(
+ "xorq %[t64], %[t64] \n"
+ "xorl %[t32], %[t32] \n"
+ "stc \n"
+ "adcq %[t64], (%[out]) \n"
+ "adcl %[t32], 8(%[out]) \n"
+ : [t64] "=&r"(t64), [t32] "=&r"(t32)
+ : [out] "D"(n)
+ : "memory", "flags", "cc");
+ return;
+ } else if (nlen == 24U) {
+ __asm__ __volatile__(
+ "movq $1, %[t64] \n"
+ "xorq %[t64_2], %[t64_2] \n"
+ "addq %[t64], (%[out]) \n"
+ "adcq %[t64_2], 8(%[out]) \n"
+ "adcq %[t64_2], 16(%[out]) \n"
+ : [t64] "=&r"(t64), [t64_2] "=&r"(t64_2)
+ : [out] "D"(n)
+ : "memory", "flags", "cc");
+ return;
+ } else if (nlen == 8U) {
+ __asm__ __volatile__("incq (%[out]) \n"
+ :
+ : [out] "D"(n)
+ : "memory", "flags", "cc");
+ return;
+ }
+#endif
+ for (; i < nlen; i++) {
+ c += (uint_fast16_t) n[i];
+ n[i] = (unsigned char) c;
+ c >>= 8;
+ }
+}
+
+void
+sodium_add(unsigned char *a, const unsigned char *b, const size_t len)
+{
+ size_t i = 0U;
+ uint_fast16_t c = 0U;
+
+#ifdef HAVE_AMD64_ASM
+ uint64_t t64, t64_2, t64_3;
+ uint32_t t32;
+
+ if (len == 12U) {
+ __asm__ __volatile__(
+ "movq (%[in]), %[t64] \n"
+ "movl 8(%[in]), %[t32] \n"
+ "addq %[t64], (%[out]) \n"
+ "adcl %[t32], 8(%[out]) \n"
+ : [t64] "=&r"(t64), [t32] "=&r"(t32)
+ : [in] "S"(b), [out] "D"(a)
+ : "memory", "flags", "cc");
+ return;
+ } else if (len == 24U) {
+ __asm__ __volatile__(
+ "movq (%[in]), %[t64] \n"
+ "movq 8(%[in]), %[t64_2] \n"
+ "movq 16(%[in]), %[t64_3] \n"
+ "addq %[t64], (%[out]) \n"
+ "adcq %[t64_2], 8(%[out]) \n"
+ "adcq %[t64_3], 16(%[out]) \n"
+ : [t64] "=&r"(t64), [t64_2] "=&r"(t64_2), [t64_3] "=&r"(t64_3)
+ : [in] "S"(b), [out] "D"(a)
+ : "memory", "flags", "cc");
+ return;
+ } else if (len == 8U) {
+ __asm__ __volatile__(
+ "movq (%[in]), %[t64] \n"
+ "addq %[t64], (%[out]) \n"
+ : [t64] "=&r"(t64)
+ : [in] "S"(b), [out] "D"(a)
+ : "memory", "flags", "cc");
+ return;
+ }
+#endif
+ for (; i < len; i++) {
+ c += (uint_fast16_t) a[i] + (uint_fast16_t) b[i];
+ a[i] = (unsigned char) c;
+ c >>= 8;
+ }
+}
+
+int
+_sodium_alloc_init(void)
+{
+#ifdef HAVE_ALIGNED_MALLOC
+# if defined(_SC_PAGESIZE)
+ long page_size_ = sysconf(_SC_PAGESIZE);
+ if (page_size_ > 0L) {
+ page_size = (size_t) page_size_;
+ }
+# elif defined(WINAPI_DESKTOP)
+ SYSTEM_INFO si;
+ GetSystemInfo(&si);
+ page_size = (size_t) si.dwPageSize;
+# endif
+ if (page_size < CANARY_SIZE || page_size < sizeof(size_t)) {
+ sodium_misuse(); /* LCOV_EXCL_LINE */
+ }
+#endif
+ randombytes_buf(canary, sizeof canary);
+
+ return 0;
+}
+
+int
+sodium_mlock(void *const addr, const size_t len)
+{
+#if defined(MADV_DONTDUMP) && defined(HAVE_MADVISE)
+ (void) madvise(addr, len, MADV_DONTDUMP);
+#endif
+#ifdef HAVE_MLOCK
+ return mlock(addr, len);
+#elif defined(WINAPI_DESKTOP)
+ return -(VirtualLock(addr, len) == 0);
+#else
+ errno = ENOSYS;
+ return -1;
+#endif
+}
+
+int
+sodium_munlock(void *const addr, const size_t len)
+{
+ sodium_memzero(addr, len);
+#if defined(MADV_DODUMP) && defined(HAVE_MADVISE)
+ (void) madvise(addr, len, MADV_DODUMP);
+#endif
+#ifdef HAVE_MLOCK
+ return munlock(addr, len);
+#elif defined(WINAPI_DESKTOP)
+ return -(VirtualUnlock(addr, len) == 0);
+#else
+ errno = ENOSYS;
+ return -1;
+#endif
+}
+
+static int
+_mprotect_noaccess(void *ptr, size_t size)
+{
+#ifdef HAVE_MPROTECT
+ return mprotect(ptr, size, PROT_NONE);
+#elif defined(WINAPI_DESKTOP)
+ DWORD old;
+ return -(VirtualProtect(ptr, size, PAGE_NOACCESS, &old) == 0);
+#else
+ errno = ENOSYS;
+ return -1;
+#endif
+}
+
+static int
+_mprotect_readonly(void *ptr, size_t size)
+{
+#ifdef HAVE_MPROTECT
+ return mprotect(ptr, size, PROT_READ);
+#elif defined(WINAPI_DESKTOP)
+ DWORD old;
+ return -(VirtualProtect(ptr, size, PAGE_READONLY, &old) == 0);
+#else
+ errno = ENOSYS;
+ return -1;
+#endif
+}
+
+static int
+_mprotect_readwrite(void *ptr, size_t size)
+{
+#ifdef HAVE_MPROTECT
+ return mprotect(ptr, size, PROT_READ | PROT_WRITE);
+#elif defined(WINAPI_DESKTOP)
+ DWORD old;
+ return -(VirtualProtect(ptr, size, PAGE_READWRITE, &old) == 0);
+#else
+ errno = ENOSYS;
+ return -1;
+#endif
+}
+
+#ifdef HAVE_ALIGNED_MALLOC
+
+__attribute__((noreturn)) static void
+_out_of_bounds(void)
+{
+# ifdef SIGSEGV
+ raise(SIGSEGV);
+# elif defined(SIGKILL)
+ raise(SIGKILL);
+# endif
+ abort(); /* not something we want any higher-level API to catch */
+} /* LCOV_EXCL_LINE */
+
+static inline size_t
+_page_round(const size_t size)
+{
+ const size_t page_mask = page_size - 1U;
+
+ return (size + page_mask) & ~page_mask;
+}
+
+static __attribute__((malloc)) unsigned char *
+_alloc_aligned(const size_t size)
+{
+ void *ptr;
+
+# if defined(MAP_ANON) && defined(HAVE_MMAP)
+ if ((ptr = mmap(NULL, size, PROT_READ | PROT_WRITE,
+ MAP_ANON | MAP_PRIVATE | MAP_NOCORE, -1, 0)) ==
+ MAP_FAILED) {
+ ptr = NULL; /* LCOV_EXCL_LINE */
+ } /* LCOV_EXCL_LINE */
+# elif defined(HAVE_POSIX_MEMALIGN)
+ if (posix_memalign(&ptr, page_size, size) != 0) {
+ ptr = NULL; /* LCOV_EXCL_LINE */
+ } /* LCOV_EXCL_LINE */
+# elif defined(WINAPI_DESKTOP)
+ ptr = VirtualAlloc(NULL, size, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
+# else
+# error Bug
+# endif
+ return (unsigned char *) ptr;
+}
+
+static void
+_free_aligned(unsigned char *const ptr, const size_t size)
+{
+# if defined(MAP_ANON) && defined(HAVE_MMAP)
+ (void) munmap(ptr, size);
+# elif defined(HAVE_POSIX_MEMALIGN)
+ free(ptr);
+# elif defined(WINAPI_DESKTOP)
+ VirtualFree(ptr, 0U, MEM_RELEASE);
+# else
+# error Bug
+#endif
+}
+
+static unsigned char *
+_unprotected_ptr_from_user_ptr(void *const ptr)
+{
+ uintptr_t unprotected_ptr_u;
+ unsigned char *canary_ptr;
+ size_t page_mask;
+
+ canary_ptr = ((unsigned char *) ptr) - sizeof canary;
+ page_mask = page_size - 1U;
+ unprotected_ptr_u = ((uintptr_t) canary_ptr & (uintptr_t) ~page_mask);
+ if (unprotected_ptr_u <= page_size * 2U) {
+ sodium_misuse(); /* LCOV_EXCL_LINE */
+ }
+ return (unsigned char *) unprotected_ptr_u;
+}
+
+#endif /* HAVE_ALIGNED_MALLOC */
+
+#ifndef HAVE_ALIGNED_MALLOC
+static __attribute__((malloc)) void *
+_sodium_malloc(const size_t size)
+{
+ return malloc(size > (size_t) 0U ? size : (size_t) 1U);
+}
+#else
+static __attribute__((malloc)) void *
+_sodium_malloc(const size_t size)
+{
+ void *user_ptr;
+ unsigned char *base_ptr;
+ unsigned char *canary_ptr;
+ unsigned char *unprotected_ptr;
+ size_t size_with_canary;
+ size_t total_size;
+ size_t unprotected_size;
+
+ if (size >= (size_t) SIZE_MAX - page_size * 4U) {
+ errno = ENOMEM;
+ return NULL;
+ }
+ if (page_size <= sizeof canary || page_size < sizeof unprotected_size) {
+ sodium_misuse(); /* LCOV_EXCL_LINE */
+ }
+ size_with_canary = (sizeof canary) + size;
+ unprotected_size = _page_round(size_with_canary);
+ total_size = page_size + page_size + unprotected_size + page_size;
+ if ((base_ptr = _alloc_aligned(total_size)) == NULL) {
+ return NULL; /* LCOV_EXCL_LINE */
+ }
+ unprotected_ptr = base_ptr + page_size * 2U;
+ _mprotect_noaccess(base_ptr + page_size, page_size);
+# ifndef HAVE_PAGE_PROTECTION
+ memcpy(unprotected_ptr + unprotected_size, canary, sizeof canary);
+# endif
+ _mprotect_noaccess(unprotected_ptr + unprotected_size, page_size);
+ sodium_mlock(unprotected_ptr, unprotected_size);
+ canary_ptr =
+ unprotected_ptr + _page_round(size_with_canary) - size_with_canary;
+ user_ptr = canary_ptr + sizeof canary;
+ memcpy(canary_ptr, canary, sizeof canary);
+ memcpy(base_ptr, &unprotected_size, sizeof unprotected_size);
+ _mprotect_readonly(base_ptr, page_size);
+ assert(_unprotected_ptr_from_user_ptr(user_ptr) == unprotected_ptr);
+
+ return user_ptr;
+}
+#endif /* !HAVE_ALIGNED_MALLOC */
+
+__attribute__((malloc)) void *
+sodium_malloc(const size_t size)
+{
+ void *ptr;
+
+ if ((ptr = _sodium_malloc(size)) == NULL) {
+ return NULL;
+ }
+ memset(ptr, (int) GARBAGE_VALUE, size);
+
+ return ptr;
+}
+
+__attribute__((malloc)) void *
+sodium_allocarray(size_t count, size_t size)
+{
+ if (count > (size_t) 0U && size >= (size_t) SIZE_MAX / count) {
+ errno = ENOMEM;
+ return NULL;
+ }
+ return sodium_malloc(count * size);
+}
+
+#ifndef HAVE_ALIGNED_MALLOC
+void
+sodium_free(void *ptr)
+{
+ free(ptr);
+}
+#else
+void
+sodium_free(void *ptr)
+{
+ unsigned char *base_ptr;
+ unsigned char *canary_ptr;
+ unsigned char *unprotected_ptr;
+ size_t total_size;
+ size_t unprotected_size;
+
+ if (ptr == NULL) {
+ return;
+ }
+ canary_ptr = ((unsigned char *) ptr) - sizeof canary;
+ unprotected_ptr = _unprotected_ptr_from_user_ptr(ptr);
+ base_ptr = unprotected_ptr - page_size * 2U;
+ memcpy(&unprotected_size, base_ptr, sizeof unprotected_size);
+ total_size = page_size + page_size + unprotected_size + page_size;
+ _mprotect_readwrite(base_ptr, total_size);
+ if (sodium_memcmp(canary_ptr, canary, sizeof canary) != 0) {
+ _out_of_bounds();
+ }
+# ifndef HAVE_PAGE_PROTECTION
+ if (sodium_memcmp(unprotected_ptr + unprotected_size, canary,
+ sizeof canary) != 0) {
+ _out_of_bounds();
+ }
+# endif
+ sodium_munlock(unprotected_ptr, unprotected_size);
+ _free_aligned(base_ptr, total_size);
+}
+#endif /* HAVE_ALIGNED_MALLOC */
+
+#ifndef HAVE_PAGE_PROTECTION
+static int
+_sodium_mprotect(void *ptr, int (*cb)(void *ptr, size_t size))
+{
+ (void) ptr;
+ (void) cb;
+ errno = ENOSYS;
+ return -1;
+}
+#else
+static int
+_sodium_mprotect(void *ptr, int (*cb)(void *ptr, size_t size))
+{
+ unsigned char *base_ptr;
+ unsigned char *unprotected_ptr;
+ size_t unprotected_size;
+
+ unprotected_ptr = _unprotected_ptr_from_user_ptr(ptr);
+ base_ptr = unprotected_ptr - page_size * 2U;
+ memcpy(&unprotected_size, base_ptr, sizeof unprotected_size);
+
+ return cb(unprotected_ptr, unprotected_size);
+}
+#endif
+
+int
+sodium_mprotect_noaccess(void *ptr)
+{
+ return _sodium_mprotect(ptr, _mprotect_noaccess);
+}
+
+int
+sodium_mprotect_readonly(void *ptr)
+{
+ return _sodium_mprotect(ptr, _mprotect_readonly);
+}
+
+int
+sodium_mprotect_readwrite(void *ptr)
+{
+ return _sodium_mprotect(ptr, _mprotect_readwrite);
+}
+
+int
+sodium_pad(size_t *padded_buflen_p, unsigned char *buf,
+ size_t unpadded_buflen, size_t blocksize, size_t max_buflen)
+{
+ unsigned char *tail;
+ size_t i;
+ size_t xpadlen;
+ size_t xpadded_len;
+ volatile unsigned char mask;
+ unsigned char barrier_mask;
+
+ if (blocksize <= 0U) {
+ return -1;
+ }
+ xpadlen = blocksize - 1U;
+ if ((blocksize & (blocksize - 1U)) == 0U) {
+ xpadlen -= unpadded_buflen & (blocksize - 1U);
+ } else {
+ xpadlen -= unpadded_buflen % blocksize;
+ }
+ if ((size_t) SIZE_MAX - unpadded_buflen <= xpadlen) {
+ sodium_misuse();
+ }
+ xpadded_len = unpadded_buflen + xpadlen;
+ if (xpadded_len >= max_buflen) {
+ return -1;
+ }
+ tail = &buf[xpadded_len];
+ if (padded_buflen_p != NULL) {
+ *padded_buflen_p = xpadded_len + 1U;
+ }
+ mask = 0U;
+ for (i = 0; i < blocksize; i++) {
+ barrier_mask = (unsigned char) (((i ^ xpadlen) - 1U) >> 8);
+ tail[-i] = (tail[-i] & mask) | (0x80 & barrier_mask);
+ mask |= barrier_mask;
+ }
+ return 0;
+}
+
+int
+sodium_unpad(size_t *unpadded_buflen_p, const unsigned char *buf,
+ size_t padded_buflen, size_t blocksize)
+{
+ const unsigned char *tail;
+ unsigned char acc = 0U;
+ unsigned char c;
+ unsigned char valid = 0U;
+ volatile size_t pad_len = 0U;
+ size_t i;
+ size_t is_barrier;
+
+ if (padded_buflen < blocksize || blocksize <= 0U) {
+ return -1;
+ }
+ tail = &buf[padded_buflen - 1U];
+
+ for (i = 0U; i < blocksize; i++) {
+ c = tail[-i];
+ is_barrier =
+ (( (acc - 1U) & (pad_len - 1U) & ((c ^ 0x80) - 1U) ) >> 8) & 1U;
+ acc |= c;
+ pad_len |= i & (1U + ~is_barrier);
+ valid |= (unsigned char) is_barrier;
+ }
+ *unpadded_buflen_p = padded_buflen - 1U - pad_len;
+
+ return (int) (valid - 1U);
+}