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path-lookup: properly chase paths when reducing with root dir (#8750)

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Let's make this correct.
This commit is contained in:
Lennart Poettering 2018-04-18 16:19:46 +02:00 committed by GitHub
parent 57ea45e11a
commit d2bcd0ba75
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 48 additions and 13 deletions
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40
src/basic/fs-util.c
View File

@ -951,6 +951,46 @@ int chase_symlinks_and_opendir(
return 0;
}
int chase_symlinks_and_stat(
const char *path,
const char *root,
unsigned chase_flags,
char **ret_path,
struct stat *ret_stat) {
_cleanup_close_ int path_fd = -1;
_cleanup_free_ char *p = NULL;
assert(path);
assert(ret_stat);
if (chase_flags & CHASE_NONEXISTENT)
return -EINVAL;
if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) {
/* Shortcut this call if none of the special features of this call are requested */
if (stat(path, ret_stat) < 0)
return -errno;
return 1;
}
path_fd = chase_symlinks(path, root, chase_flags|CHASE_OPEN, ret_path ? &p : NULL);
if (path_fd < 0)
return path_fd;
if (fstat(path_fd, ret_stat) < 0)
return -errno;
if (ret_path)
*ret_path = TAKE_PTR(p);
if (chase_flags & CHASE_OPEN)
return TAKE_FD(path_fd);
return 1;
}
int access_fd(int fd, int mode) {
char p[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(fd) + 1];
int r;

1
src/basic/fs-util.h
View File

@ -81,6 +81,7 @@ int chase_symlinks(const char *path_with_prefix, const char *root, unsigned flag
int chase_symlinks_and_open(const char *path, const char *root, unsigned chase_flags, int open_flags, char **ret_path);
int chase_symlinks_and_opendir(const char *path, const char *root, unsigned chase_flags, char **ret_path, DIR **ret_dir);
int chase_symlinks_and_stat(const char *path, const char *root, unsigned chase_flags, char **ret_path, struct stat *ret_stat);
/* Useful for usage with _cleanup_(), removes a directory and frees the pointer */
static inline void rmdir_and_free(char *p) {

20
src/shared/path-lookup.c
View File

@ -723,14 +723,13 @@ int lookup_paths_reduce(LookupPaths *p) {
assert(p);
/* Drop duplicates and non-existing directories from the search path. We figure out whether two directories are
* the same by comparing their device and inode numbers. Note one special tweak: when we have a root path set,
* we do not follow symlinks when retrieving them, because the kernel wouldn't take the root prefix into
* account when following symlinks. When we have no root path set this restriction does not apply however. */
* the same by comparing their device and inode numbers. */
if (!p->search_path)
return 0;
while (p->search_path[c]) {
_cleanup_free_ char *chased = NULL;
struct stat st;
unsigned k;
@ -742,25 +741,20 @@ int lookup_paths_reduce(LookupPaths *p) {
continue;
}
if (p->root_dir)
r = lstat(p->search_path[c], &st);
else
r = stat(p->search_path[c], &st);
r = chase_symlinks_and_stat(p->search_path[c], p->root_dir, 0, NULL, &st);
if (r == -ENOENT)
goto remove_item;
if (r < 0) {
if (errno == ENOENT)
goto remove_item;
/* If something we don't grok happened, let's better leave it in. */
log_debug_errno(errno, "Failed to stat %s: %m", p->search_path[c]);
log_debug_errno(r, "Failed to chase and stat %s: %m", p->search_path[c]);
c++;
continue;
}
for (k = 0; k < n_stats; k++) {
for (k = 0; k < n_stats; k++)
if (stats[k].st_dev == st.st_dev &&
stats[k].st_ino == st.st_ino)
break;
}
if (k < n_stats) /* Is there already an entry with the same device/inode? */
goto remove_item;