From 9fe64023e32ab9e3fbbfeefc2168a49b748a1846 Mon Sep 17 00:00:00 2001

From: Samuel Cabrero <scabrero@suse.de>

Date: Fri, 19 Jul 2019 12:24:56 +0200

Subject: [PATCH 21/21] MONITOR: Resolve symlinks setting the inotify watchers

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If resolv.conf is a symlink and sssd starts before getting an address

from dhcp the data provider will remain forever offline, as the watched

parent directory is the directory containing the symlink.

Signed-off-by: Samuel Cabrero <scabrero@suse.de>

Reviewed-by: Sumit Bose <sbose@redhat.com>

(cherry picked from commit d57c67e4efc64a16b874b46eb9670fdc9c73a39f)

Reviewed-by: Pavel Březina <pbrezina@redhat.com>

---

 src/util/inotify.c | 55 +++++++++++++++++++++++++++++++++++++++++++---

 1 file changed, 52 insertions(+), 3 deletions(-)

diff --git a/src/util/inotify.c b/src/util/inotify.c

index 2e2dc1a6e..ffc15ad4d 100644

--- a/src/util/inotify.c

+++ b/src/util/inotify.c

@@ -381,13 +381,62 @@ static int watch_ctx_destructor(void *memptr)

     return 0;

 }

+static errno_t resolve_filename(struct snotify_ctx *snctx,

+                                const char *filename,

+                                char *resolved,

+                                size_t resolved_size)

+{

+    /* NOTE: The code below relies in the GNU extensions for realpath,

+     * which will store in 'resolved' the prefix of 'filename' that does

+     * not exists if realpath call fails and errno is set to ENOENT */

+    if (realpath(filename, resolved) == NULL) {

+        char fcopy[PATH_MAX + 1];

+        char *p;

+        struct stat st;

+

+        if (errno != ENOENT) {

+            return errno;

+        }

+

+        /* Check if the unique missing component is the basename. The

+         * dirname must exist to be notified watching the parent dir. */

+        strncpy(fcopy, filename, sizeof(fcopy) - 1);

+        fcopy[PATH_MAX] = '\0';

+

+        p = dirname(fcopy);

+        if (p == NULL) {

+            return EIO;

+        }

+

+        if (stat(p, &st) == -1) {

+            return errno;

+        }

+

+        /* The basedir exist, check the caller requested to watch it.

+         * Otherwise return error as never will be notified. */

+

+        if ((snctx->snotify_flags & SNOTIFY_WATCH_DIR) == 0) {

+            return ENOENT;

+        }

+    }

+

+    return EOK;

+}

+

 static errno_t copy_filenames(struct snotify_ctx *snctx,

                               const char *filename)

 {

     char *p;

+    char resolved[PATH_MAX + 1];

     char fcopy[PATH_MAX + 1];

+    errno_t ret;

+

+    ret = resolve_filename(snctx, filename, resolved, sizeof(resolved));

+    if (ret != EOK) {

+		return ret;

+    }

-    strncpy(fcopy, filename, sizeof(fcopy) - 1);

+    strncpy(fcopy, resolved, sizeof(fcopy) - 1);

     fcopy[PATH_MAX] = '\0';

     p = dirname(fcopy);

@@ -400,7 +449,7 @@ static errno_t copy_filenames(struct snotify_ctx *snctx,

         return ENOMEM;

     }

-    strncpy(fcopy, filename, sizeof(fcopy) - 1);

+    strncpy(fcopy, resolved, sizeof(fcopy) - 1);

     fcopy[PATH_MAX] = '\0';

     p = basename(fcopy);

@@ -413,7 +462,7 @@ static errno_t copy_filenames(struct snotify_ctx *snctx,

         return ENOMEM;

     }

-    snctx->filename = talloc_strdup(snctx, filename);

+    snctx->filename = talloc_strdup(snctx, resolved);

     if (snctx->filename == NULL) {

         return ENOMEM;

     }

-- 

2.21.1