From 50432108fb3ef826301626b94c5e82ad2ab2bd75 Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Mon, 8 Jan 2018 21:43:23 -0500 Subject: stat: New wrapper around the stat() family This lets bfs transparently support the new statx() system call on Linux, giving it access to file birth times. --- stat.c | 243 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 243 insertions(+) create mode 100644 stat.c (limited to 'stat.c') diff --git a/stat.c b/stat.c new file mode 100644 index 0000000..4f1c2fc --- /dev/null +++ b/stat.c @@ -0,0 +1,243 @@ +/**************************************************************************** + * bfs * + * Copyright (C) 2018 Tavian Barnes * + * * + * 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 +#include +#include +#include +#include +#include + +#if __linux__ +# include +# include +# include +#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 +} -- cgit v1.2.3