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machine-id-setup: move code to use chase() (#35979)

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I just wanted to switch the machine id setup code to use chase() or its
changes, given it supports --root=/--image= operation. That turned out
to be a rabbit hole, and became much bigger...
This commit is contained in:
Lennart Poettering
2025-01-20 21:18:24 +01:00
committed by GitHub
parent 52e2033ebc 09b70f7cc9
commit c66a7ca6e5
9 changed files with 289 additions and 103 deletions
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src/basic/chase.c
+27 -15
View File
@@ -89,9 +89,8 @@ int chaseat(int dir_fd, const char *path, ChaseFlags flags, char **ret_path, int
int r;
assert(!FLAGS_SET(flags, CHASE_PREFIX_ROOT));
assert(!FLAGS_SET(flags, CHASE_MUST_BE_DIRECTORY|CHASE_MUST_BE_REGULAR));
assert(!FLAGS_SET(flags, CHASE_STEP|CHASE_EXTRACT_FILENAME));
assert(!FLAGS_SET(flags, CHASE_TRAIL_SLASH|CHASE_EXTRACT_FILENAME));
assert(!FLAGS_SET(flags, CHASE_MKDIR_0755) || (flags & (CHASE_NONEXISTENT | CHASE_PARENT)) != 0);
assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
/* Either the file may be missing, or we return an fd to the final object, but both make no sense */
@@ -244,8 +243,15 @@ int chaseat(int dir_fd, const char *path, ChaseFlags flags, char **ret_path, int
if (root_fd < 0)
return -errno;
if (FLAGS_SET(flags, CHASE_TRAIL_SLASH))
append_trail_slash = ENDSWITH_SET(buffer, "/", "/.");
if (ENDSWITH_SET(buffer, "/", "/.")) {
flags |= CHASE_MUST_BE_DIRECTORY;
if (FLAGS_SET(flags, CHASE_TRAIL_SLASH))
append_trail_slash = true;
} else if (dot_or_dot_dot(buffer) || endswith(buffer, "/.."))
flags |= CHASE_MUST_BE_DIRECTORY;
if (FLAGS_SET(flags, CHASE_PARENT))
flags |= CHASE_MUST_BE_DIRECTORY;
for (todo = buffer;;) {
_cleanup_free_ char *first = NULL;
@@ -256,19 +262,15 @@ int chaseat(int dir_fd, const char *path, ChaseFlags flags, char **ret_path, int
r = path_find_first_component(&todo, /* accept_dot_dot= */ true, &e);
if (r < 0)
return r;
if (r == 0) { /* We reached the end. */
if (append_trail_slash)
if (!strextend(&done, "/"))
return -ENOMEM;
if (r == 0) /* We reached the end. */
break;
}
first = strndup(e, r);
if (!first)
return -ENOMEM;
/* Two dots? Then chop off the last bit of what we already found out. */
if (path_equal(first, "..")) {
if (streq(first, "..")) {
_cleanup_free_ char *parent = NULL;
_cleanup_close_ int fd_parent = -EBADF;
struct stat st_parent;
@@ -370,13 +372,13 @@ int chaseat(int dir_fd, const char *path, ChaseFlags flags, char **ret_path, int
if (r != -ENOENT)
return r;
if (!isempty(todo) && !path_is_safe(todo))
if (!isempty(todo) && !path_is_safe(todo)) /* Refuse parent/mkdir handling if suffix contains ".." or something weird */
return r;
if (FLAGS_SET(flags, CHASE_MKDIR_0755) && !isempty(todo)) {
if (FLAGS_SET(flags, CHASE_MKDIR_0755) && (!isempty(todo) || !(flags & (CHASE_PARENT|CHASE_NONEXISTENT)))) {
child = xopenat_full(fd,
first,
O_DIRECTORY|O_CREAT|O_EXCL|O_NOFOLLOW|O_CLOEXEC,
O_DIRECTORY|O_CREAT|O_EXCL|O_NOFOLLOW|O_PATH|O_CLOEXEC,
/* xopen_flags = */ 0,
0755);
if (child < 0)
@@ -477,12 +479,18 @@ int chaseat(int dir_fd, const char *path, ChaseFlags flags, char **ret_path, int
close_and_replace(fd, child);
}
if (FLAGS_SET(flags, CHASE_PARENT)) {
if (FLAGS_SET(flags, CHASE_MUST_BE_DIRECTORY)) {
r = stat_verify_directory(&st);
if (r < 0)
return r;
}
if (FLAGS_SET(flags, CHASE_MUST_BE_REGULAR)) {
r = stat_verify_regular(&st);
if (r < 0)
return r;
}
if (ret_path) {
if (FLAGS_SET(flags, CHASE_EXTRACT_FILENAME) && done) {
_cleanup_free_ char *f = NULL;
@@ -497,11 +505,15 @@ int chaseat(int dir_fd, const char *path, ChaseFlags flags, char **ret_path, int
if (!done) {
assert(!need_absolute || FLAGS_SET(flags, CHASE_EXTRACT_FILENAME));
done = strdup(append_trail_slash ? "./" : ".");
done = strdup(".");
if (!done)
return -ENOMEM;
}
if (append_trail_slash)
if (!strextend(&done, "/"))
return -ENOMEM;
*ret_path = TAKE_PTR(done);
}
src/basic/chase.h
+3 -5
View File
@@ -27,12 +27,10 @@ typedef enum ChaseFlags {
* also points to the result path even if this flag is set.
* When this specified, chase() will succeed with 1 even if the
* file points to the last path component does not exist. */
CHASE_MKDIR_0755 = 1 << 11, /* Create any missing parent directories in the given path. This
* needs to be set with CHASE_NONEXISTENT and/or CHASE_PARENT.
* Note, chase_and_open() or friends always add CHASE_PARENT flag
* when internally call chase(), hence CHASE_MKDIR_0755 can be
* safely set without CHASE_NONEXISTENT and CHASE_PARENT. */
CHASE_MKDIR_0755 = 1 << 11, /* Create any missing directories in the given path. */
CHASE_EXTRACT_FILENAME = 1 << 12, /* Only return the last component of the resolved path */
CHASE_MUST_BE_DIRECTORY = 1 << 13, /* Fail if returned inode fd is not a dir */
CHASE_MUST_BE_REGULAR = 1 << 14, /* Fail if returned inode fd is not a regular file */
} ChaseFlags;
bool unsafe_transition(const struct stat *a, const struct stat *b);