From f8eaf398c667ab4455bb480fcbece7240aeeb9f3 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
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(-)
(limited to 'src')
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 {
--
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