From 430fbf8e7ff4368f6d43a8f86e0bc6494b0a979c Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 25 Apr 2016 00:18:27 +0200
Subject: [PATCH] journal: add inotify watches by-fd instead of by-path

This is slightly nicer, since we actually watch the directories we opened and
enumerate. However, primarily this is preparation for adding support for
opening journal files by fd without specifying any path, to be added in a later
commit.
---
 src/basic/fs-util.c      | 15 +++++++++++++++
 src/basic/fs-util.h      |  2 ++
 src/journal/sd-journal.c | 10 +++++-----
 3 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/basic/fs-util.c b/src/basic/fs-util.c
index 51268828af..e24e7036f7 100644
--- a/src/basic/fs-util.c
+++ b/src/basic/fs-util.c
@@ -38,6 +38,7 @@
 #include "mkdir.h"
 #include "parse-util.h"
 #include "path-util.h"
+#include "stdio-util.h"
 #include "string-util.h"
 #include "strv.h"
 #include "time-util.h"
@@ -493,3 +494,17 @@ int get_files_in_directory(const char *path, char ***list) {
 
         return n;
 }
+
+int inotify_add_watch_fd(int fd, int what, uint32_t mask) {
+        char path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1];
+        int r;
+
+        /* This is like inotify_add_watch(), except that the file to watch is not referenced by a path, but by an fd */
+        xsprintf(path, "/proc/self/fd/%i", what);
+
+        r = inotify_add_watch(fd, path, mask);
+        if (r < 0)
+                return -errno;
+
+        return r;
+}
diff --git a/src/basic/fs-util.h b/src/basic/fs-util.h
index 0d23f8635f..517b599d6f 100644
--- a/src/basic/fs-util.h
+++ b/src/basic/fs-util.h
@@ -72,3 +72,5 @@ union inotify_event_buffer {
         struct inotify_event ev;
         uint8_t raw[INOTIFY_EVENT_MAX];
 };
+
+int inotify_add_watch_fd(int fd, int what, uint32_t mask);
diff --git a/src/journal/sd-journal.c b/src/journal/sd-journal.c
index 3c21d4129e..7ae8941a5e 100644
--- a/src/journal/sd-journal.c
+++ b/src/journal/sd-journal.c
@@ -1420,10 +1420,10 @@ static int add_directory(sd_journal *j, const char *prefix, const char *dirname)
 
         if (m->wd <= 0 && j->inotify_fd >= 0) {
 
-                m->wd = inotify_add_watch(j->inotify_fd, m->path,
-                                          IN_CREATE|IN_MOVED_TO|IN_MODIFY|IN_ATTRIB|IN_DELETE|
-                                          IN_DELETE_SELF|IN_MOVE_SELF|IN_UNMOUNT|IN_MOVED_FROM|
-                                          IN_ONLYDIR);
+                m->wd = inotify_add_watch_fd(j->inotify_fd, dirfd(d),
+                                             IN_CREATE|IN_MOVED_TO|IN_MODIFY|IN_ATTRIB|IN_DELETE|
+                                             IN_DELETE_SELF|IN_MOVE_SELF|IN_UNMOUNT|IN_MOVED_FROM|
+                                             IN_ONLYDIR);
 
                 if (m->wd > 0 && hashmap_put(j->directories_by_wd, INT_TO_PTR(m->wd), m) < 0)
                         inotify_rm_watch(j->inotify_fd, m->wd);
@@ -1505,7 +1505,7 @@ static int add_root_directory(sd_journal *j, const char *p, bool missing_ok) {
 
         if (m->wd <= 0 && j->inotify_fd >= 0) {
 
-                m->wd = inotify_add_watch(j->inotify_fd, m->path,
+                m->wd = inotify_add_watch_fd(j->inotify_fd, dirfd(d),
                                           IN_CREATE|IN_MOVED_TO|IN_MODIFY|IN_ATTRIB|IN_DELETE|
                                           IN_ONLYDIR);