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Merge pull request #19726 from poettering/path-event-symlink

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teach .path units to notice events on paths with components that are symlinks
This commit is contained in:
Yu Watanabe 2021-05-26 10:51:00 +09:00 committed by GitHub
commit 89c629fc4b
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1 changed files with 61 additions and 37 deletions
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98
src/core/path.c
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@ -36,10 +36,10 @@ static int path_dispatch_io(sd_event_source *source, int fd, uint32_t revents, v
int path_spec_watch(PathSpec *s, sd_event_io_handler_t handler) {
static const int flags_table[_PATH_TYPE_MAX] = {
[PATH_EXISTS] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
[PATH_EXISTS_GLOB] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
[PATH_CHANGED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO,
[PATH_MODIFIED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO|IN_MODIFY,
[PATH_EXISTS] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
[PATH_EXISTS_GLOB] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
[PATH_CHANGED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO,
[PATH_MODIFIED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO|IN_MODIFY,
[PATH_DIRECTORY_NOT_EMPTY] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CREATE|IN_MOVED_TO,
};
@ -55,13 +55,15 @@ int path_spec_watch(PathSpec *s, sd_event_io_handler_t handler) {
s->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC);
if (s->inotify_fd < 0) {
r = -errno;
r = log_error_errno(errno, "Failed to allocate inotify fd: %m");
goto fail;
}
r = sd_event_add_io(s->unit->manager->event, &s->event_source, s->inotify_fd, EPOLLIN, handler, s);
if (r < 0)
if (r < 0) {
log_error_errno(r, "Failed to add inotify fd to event loop: %m");
goto fail;
}
(void) sd_event_source_set_description(s->event_source, "path");
@ -69,9 +71,9 @@ int path_spec_watch(PathSpec *s, sd_event_io_handler_t handler) {
assert(!strstr(s->path, "//"));
for (slash = strchr(s->path, '/'); ; slash = strchr(slash+1, '/')) {
char *cut = NULL;
int flags;
char tmp;
bool incomplete = false;
int flags, wd = -1;
char tmp, *cut;
if (slash) {
cut = slash + (slash == s->path);
@ -79,28 +81,50 @@ int path_spec_watch(PathSpec *s, sd_event_io_handler_t handler) {
*cut = '\0';
flags = IN_MOVE_SELF | IN_DELETE_SELF | IN_ATTRIB | IN_CREATE | IN_MOVED_TO;
} else
} else {
cut = NULL;
flags = flags_table[s->type];
r = inotify_add_watch(s->inotify_fd, s->path, flags);
if (r < 0) {
if (IN_SET(errno, EACCES, ENOENT)) {
if (cut)
*cut = tmp;
break;
}
/* This second call to inotify_add_watch() should fail like the previous
* one and is done for logging the error in a comprehensive way. */
r = inotify_add_watch_and_warn(s->inotify_fd, s->path, flags);
if (r < 0) {
if (cut)
*cut = tmp;
goto fail;
}
/* Hmm, we succeeded in adding the watch this time... let's continue. */
}
/* If this is a symlink watch both the symlink inode and where it points to. If the inode is
* not a symlink both calls will install the same watch, which is redundant and doesn't
* hurt. */
for (int follow_symlink = 0; follow_symlink < 2; follow_symlink ++) {
uint32_t f = flags;
SET_FLAG(f, IN_DONT_FOLLOW, !follow_symlink);
wd = inotify_add_watch(s->inotify_fd, s->path, f);
if (wd < 0) {
if (IN_SET(errno, EACCES, ENOENT)) {
incomplete = true; /* This is an expected error, let's accept this
* quietly: we have an incomplete watch for
* now. */
break;
}
/* This second call to inotify_add_watch() should fail like the previous one
* and is done for logging the error in a comprehensive way. */
wd = inotify_add_watch_and_warn(s->inotify_fd, s->path, f);
if (wd < 0) {
if (cut)
*cut = tmp;
r = wd;
goto fail;
}
/* Hmm, we succeeded in adding the watch this time... let's continue. */
}
}
if (incomplete) {
if (cut)
*cut = tmp;
break;
}
exists = true;
/* Path exists, we don't need to watch parent too closely. */
@ -122,7 +146,7 @@ int path_spec_watch(PathSpec *s, sd_event_io_handler_t handler) {
oldslash = slash;
else {
/* whole path has been iterated over */
s->primary_wd = r;
s->primary_wd = wd;
break;
}
}
@ -151,7 +175,8 @@ int path_spec_fd_event(PathSpec *s, uint32_t revents) {
union inotify_event_buffer buffer;
struct inotify_event *e;
ssize_t l;
int r = 0;
assert(s);
if (revents != EPOLLIN)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
@ -165,13 +190,12 @@ int path_spec_fd_event(PathSpec *s, uint32_t revents) {
return log_error_errno(errno, "Failed to read inotify event: %m");
}
FOREACH_INOTIFY_EVENT(e, buffer, l) {
if (IN_SET(s->type, PATH_CHANGED, PATH_MODIFIED) &&
s->primary_wd == e->wd)
r = 1;
}
if (IN_SET(s->type, PATH_CHANGED, PATH_MODIFIED))
FOREACH_INOTIFY_EVENT(e, buffer, l)
if (s->primary_wd == e->wd)
return 1;
return r;
return 0;
}
static bool path_spec_check_good(PathSpec *s, bool initial, bool from_trigger_notify) {