From f8eaf398c667ab4455bb480fcbece7240aeeb9f3 Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Thu, 12 May 2022 14:18:58 -0400 Subject: stat: Factor the BFS_STAT_TRYFOLLOW retry logic out --- src/stat.c | 55 +++++++++++++++++++++++++------------------------------ 1 file changed, 25 insertions(+), 30 deletions(-) diff --git a/src/stat.c b/src/stat.c index 1cd4658..0326ba2 100644 --- a/src/stat.c +++ b/src/stat.c @@ -85,15 +85,6 @@ const char *bfs_stat_field_name(enum bfs_stat_field field) { return "???"; } -/** - * Check if we should retry a failed stat() due to a potentially broken link. - */ -static bool bfs_stat_retry(int ret, enum bfs_stat_flags flags) { - return ret != 0 - && (flags & (BFS_STAT_NOFOLLOW | BFS_STAT_TRYFOLLOW)) == BFS_STAT_TRYFOLLOW - && is_nonexistence_error(errno); -} - /** * Convert a struct stat to a struct bfs_stat. */ @@ -150,19 +141,12 @@ static void bfs_stat_convert(const struct stat *statbuf, struct bfs_stat *buf) { /** * bfs_stat() implementation backed by stat(). */ -static int bfs_stat_impl(int at_fd, const char *at_path, int at_flags, enum bfs_stat_flags flags, struct bfs_stat *buf) { +static int bfs_stat_impl(int at_fd, const char *at_path, int at_flags, struct bfs_stat *buf) { struct stat statbuf; int ret = fstatat(at_fd, at_path, &statbuf, at_flags); - - if (bfs_stat_retry(ret, 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; } @@ -188,16 +172,10 @@ static int bfs_statx(int at_fd, const char *at_path, int at_flags, unsigned int /** * bfs_stat() implementation backed by statx(). */ -static int bfs_statx_impl(int at_fd, const char *at_path, int at_flags, enum bfs_stat_flags flags, struct bfs_stat *buf) { +static int bfs_statx_impl(int at_fd, const char *at_path, int at_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, flags)) { - at_flags |= AT_SYMLINK_NOFOLLOW; - ret = bfs_statx(at_fd, at_path, at_flags, mask, &xbuf); - } - if (ret != 0) { return ret; } @@ -288,14 +266,14 @@ static int bfs_statx_impl(int at_fd, const char *at_path, int at_flags, enum bfs #endif // BFS_STATX /** - * Allows calling stat with custom at_flags. + * Calls the stat() implementation with explicit flags. */ -static int bfs_stat_explicit(int at_fd, const char *at_path, int at_flags, enum bfs_stat_flags flags, struct bfs_stat *buf) { +static int bfs_stat_explicit(int at_fd, const char *at_path, int at_flags, struct bfs_stat *buf) { #if BFS_STATX static bool has_statx = true; if (has_statx) { - int ret = bfs_statx_impl(at_fd, at_path, at_flags, flags, buf); + int ret = bfs_statx_impl(at_fd, at_path, at_flags, buf); // EPERM is commonly returned in a seccomp() sandbox that does // not allow statx() if (ret != 0 && (errno == ENOSYS || errno == EPERM)) { @@ -306,7 +284,24 @@ static int bfs_stat_explicit(int at_fd, const char *at_path, int at_flags, enum } #endif - return bfs_stat_impl(at_fd, at_path, at_flags, flags, buf); + return bfs_stat_impl(at_fd, at_path, at_flags, buf); +} + +/** + * Implements the BFS_STAT_TRYFOLLOW retry logic. + */ +static int bfs_stat_tryfollow(int at_fd, const char *at_path, int at_flags, enum bfs_stat_flags bfs_flags, struct bfs_stat *buf) { + int ret = bfs_stat_explicit(at_fd, at_path, at_flags, buf); + + if (ret != 0 + && (bfs_flags & (BFS_STAT_NOFOLLOW | BFS_STAT_TRYFOLLOW)) == BFS_STAT_TRYFOLLOW + && is_nonexistence_error(errno)) + { + at_flags |= AT_SYMLINK_NOFOLLOW; + ret = bfs_stat_explicit(at_fd, at_path, at_flags, buf); + } + + return ret; } int bfs_stat(int at_fd, const char *at_path, enum bfs_stat_flags flags, struct bfs_stat *buf) { @@ -322,7 +317,7 @@ int bfs_stat(int at_fd, const char *at_path, enum bfs_stat_flags flags, struct b #endif if (at_path) { - return bfs_stat_explicit(at_fd, at_path, at_flags, flags, buf); + return bfs_stat_tryfollow(at_fd, at_path, at_flags, flags, buf); } // Check __GNU__ to work around https://lists.gnu.org/archive/html/bug-hurd/2021-12/msg00001.html @@ -330,7 +325,7 @@ int bfs_stat(int at_fd, const char *at_path, enum bfs_stat_flags flags, struct b static bool has_at_ep = true; if (has_at_ep) { at_flags |= AT_EMPTY_PATH; - int ret = bfs_stat_explicit(at_fd, "", at_flags, flags, buf); + int ret = bfs_stat_explicit(at_fd, "", at_flags, buf); if (ret != 0 && errno == EINVAL) { has_at_ep = false; } else { -- cgit v1.2.3