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-rw-r--r--stat.c243
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diff --git a/stat.c b/stat.c
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+/****************************************************************************
+ * bfs *
+ * Copyright (C) 2018 Tavian Barnes <tavianator@tavianator.com> *
+ * *
+ * Permission to use, copy, modify, and/or distribute this software for any *
+ * purpose with or without fee is hereby granted. *
+ * *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES *
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF *
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR *
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES *
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN *
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF *
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *
+ ****************************************************************************/
+
+#include "stat.h"
+#include "util.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#if __linux__
+# include <linux/stat.h>
+# include <sys/syscall.h>
+# include <sys/sysmacros.h>
+#elif __APPLE__
+# define st_atim st_atimespec
+# define st_ctim st_ctimespec
+# define st_mtim st_mtimespec
+# define st_birthtim st_birthtimespec
+#endif
+
+/**
+ * Check if we should retry a failed stat() due to a potentially broken link.
+ */
+static bool bfs_stat_retry(int ret, int at_flags, enum bfs_stat_flag flags) {
+ return ret != 0
+ && !(at_flags & AT_SYMLINK_NOFOLLOW)
+ && (flags & BFS_STAT_BROKEN_OK)
+ && is_nonexistence_error(errno);
+}
+
+/**
+ * Convert a struct stat to a struct bfs_stat.
+ */
+static void bfs_stat_convert(const struct stat *statbuf, struct bfs_stat *buf) {
+ buf->mask = 0;
+
+ buf->dev = statbuf->st_dev;
+ buf->mask |= BFS_STAT_DEV;
+
+ buf->ino = statbuf->st_ino;
+ buf->mask |= BFS_STAT_INO;
+
+ buf->mode = statbuf->st_mode;
+ buf->mask |= BFS_STAT_TYPE | BFS_STAT_MODE;
+
+ buf->nlink = statbuf->st_nlink;
+ buf->mask |= BFS_STAT_NLINK;
+
+ buf->gid = statbuf->st_gid;
+ buf->mask |= BFS_STAT_GID;
+
+ buf->uid = statbuf->st_uid;
+ buf->mask |= BFS_STAT_UID;
+
+ buf->size = statbuf->st_size;
+ buf->mask |= BFS_STAT_SIZE;
+
+ buf->blocks = statbuf->st_blocks;
+ buf->mask |= BFS_STAT_BLOCKS;
+
+ buf->atime = statbuf->st_atim;
+ buf->mask |= BFS_STAT_ATIME;
+
+ buf->ctime = statbuf->st_ctim;
+ buf->mask |= BFS_STAT_CTIME;
+
+ buf->mtime = statbuf->st_mtim;
+ buf->mask |= BFS_STAT_MTIME;
+
+#if __APPLE__ || __FreeBSD__ || __NetBSD__
+ buf->btime = statbuf->st_birthtim;
+ buf->mask |= BFS_STAT_BTIME;
+#endif
+}
+
+/**
+ * bfs_stat() implementation backed by stat().
+ */
+static int bfs_stat_impl(int at_fd, const char *at_path, int at_flags, enum bfs_stat_flag flags, struct bfs_stat *buf) {
+ struct stat statbuf;
+ int ret = fstatat(at_fd, at_path, &statbuf, at_flags);
+
+ if (bfs_stat_retry(ret, at_flags, flags)) {
+ at_flags |= AT_SYMLINK_NOFOLLOW;
+ ret = fstatat(at_fd, at_path, &statbuf, at_flags);
+ }
+
+ if (ret == 0) {
+ bfs_stat_convert(&statbuf, buf);
+ }
+
+ return ret;
+}
+
+#ifdef STATX_BASIC_STATS
+
+/**
+ * Wrapper for the statx() system call, which has no native glibc wrapper.
+ */
+static int bfs_statx(int at_fd, const char *at_path, int at_flags, unsigned int mask, struct statx *buf) {
+ return syscall(__NR_statx, at_fd, at_path, at_flags, mask, buf);
+}
+
+/**
+ * bfs_stat() implementation backed by statx().
+ */
+static int bfs_statx_impl(int at_fd, const char *at_path, int at_flags, enum bfs_stat_flag flags, struct bfs_stat *buf) {
+ unsigned int mask = STATX_BASIC_STATS | STATX_BTIME;
+ struct statx xbuf;
+ int ret = bfs_statx(at_fd, at_path, at_flags, mask, &xbuf);
+
+ if (bfs_stat_retry(ret, at_flags, flags)) {
+ at_flags |= AT_SYMLINK_NOFOLLOW;
+ ret = bfs_statx(at_fd, at_path, at_flags, mask, &xbuf);
+ }
+
+ if (ret != 0) {
+ return ret;
+ }
+
+ if ((xbuf.stx_mask & STATX_BASIC_STATS) != STATX_BASIC_STATS) {
+ // Callers shouldn't have to check anything except BFS_STAT_BTIME
+ errno = EINVAL;
+ return -1;
+ }
+
+ buf->mask = 0;
+
+ buf->dev = makedev(xbuf.stx_dev_major, xbuf.stx_dev_minor);
+ buf->mask |= BFS_STAT_DEV;
+
+ if (xbuf.stx_mask & STATX_INO) {
+ buf->ino = xbuf.stx_ino;
+ buf->mask |= BFS_STAT_INO;
+ }
+
+ buf->mode = xbuf.stx_mode;
+ if (xbuf.stx_mask & STATX_TYPE) {
+ buf->mask |= BFS_STAT_TYPE;
+ }
+ if (xbuf.stx_mask & STATX_MODE) {
+ buf->mask |= BFS_STAT_MODE;
+ }
+
+ if (xbuf.stx_mask & STATX_NLINK) {
+ buf->nlink = xbuf.stx_nlink;
+ buf->mask |= BFS_STAT_NLINK;
+ }
+
+ if (xbuf.stx_mask & STATX_GID) {
+ buf->gid = xbuf.stx_gid;
+ buf->mask |= BFS_STAT_GID;
+ }
+
+ if (xbuf.stx_mask & STATX_UID) {
+ buf->uid = xbuf.stx_uid;
+ buf->mask |= BFS_STAT_UID;
+ }
+
+ if (xbuf.stx_mask & STATX_SIZE) {
+ buf->size = xbuf.stx_size;
+ buf->mask |= BFS_STAT_SIZE;
+ }
+
+ if (xbuf.stx_mask & STATX_BLOCKS) {
+ buf->blocks = xbuf.stx_blocks;
+ buf->mask |= BFS_STAT_BLOCKS;
+ }
+
+ if (xbuf.stx_mask & STATX_ATIME) {
+ buf->atime.tv_sec = xbuf.stx_atime.tv_sec;
+ buf->atime.tv_nsec = xbuf.stx_atime.tv_nsec;
+ buf->mask |= BFS_STAT_ATIME;
+ }
+
+ if (xbuf.stx_mask & STATX_BTIME) {
+ buf->btime.tv_sec = xbuf.stx_btime.tv_sec;
+ buf->btime.tv_nsec = xbuf.stx_btime.tv_nsec;
+ buf->mask |= BFS_STAT_BTIME;
+ }
+
+ if (xbuf.stx_mask & STATX_CTIME) {
+ buf->ctime.tv_sec = xbuf.stx_ctime.tv_sec;
+ buf->ctime.tv_nsec = xbuf.stx_ctime.tv_nsec;
+ buf->mask |= BFS_STAT_CTIME;
+ }
+
+ if (xbuf.stx_mask & STATX_MTIME) {
+ buf->mtime.tv_sec = xbuf.stx_mtime.tv_sec;
+ buf->mtime.tv_nsec = xbuf.stx_mtime.tv_nsec;
+ buf->mask |= BFS_STAT_MTIME;
+ }
+
+ return ret;
+}
+
+#endif // STATX_BASIC_STATS
+
+int bfs_stat(int at_fd, const char *at_path, int at_flags, enum bfs_stat_flag flags, struct bfs_stat *buf) {
+#ifdef STATX_BASIC_STATS
+ static bool has_statx = true;
+
+ if (has_statx) {
+ int ret = bfs_statx_impl(at_fd, at_path, at_flags, flags, buf);
+ if (ret != 0 && errno == ENOSYS) {
+ has_statx = false;
+ } else {
+ return ret;
+ }
+ }
+#endif
+
+ return bfs_stat_impl(at_fd, at_path, at_flags, flags, buf);
+}
+
+int bfs_fstat(int fd, struct bfs_stat *buf) {
+#ifdef AT_EMPTY_PATH
+ return bfs_stat(fd, "", AT_EMPTY_PATH, 0, buf);
+#else
+ struct stat statbuf;
+ int ret = fstat(fd, &statbuf);
+ if (ret == 0) {
+ bfs_stat_convert(&statbuf, buf);
+ }
+ return ret;
+#endif
+}