Be more careful when checking for empty files

If we want to avoid reading a totally empty file, it seems better
to check after we have opened the file, not before.

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>

2 files changed, 12 insertions, 0 deletions

diff --git a/src/libudev/util.c b/src/libudev/util.c
index af7477ba6f..116d723a0f 100644
--- a/src/libudev/util.c
+++ b/src/libudev/util.c
@@ -658,6 +658,17 @@ int null_or_empty_path(const char *fn) {
         return null_or_empty(&st);
 }
 
+int null_or_empty_fd(int fd) {
+        struct stat st;
+
+        assert(fd >= 0);
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        return null_or_empty(&st);
+}
+
 bool dirent_is_file_with_suffix(const struct dirent *de, const char *suffix) {
         assert(de);
 
diff --git a/src/libudev/util.h b/src/libudev/util.h
index bde7b91e6f..a38e8e61c5 100644
--- a/src/libudev/util.h
+++ b/src/libudev/util.h
@@ -222,6 +222,7 @@ int chmod_and_chown(const char *path, mode_t mode, uid_t uid, gid_t gid);
 
 bool null_or_empty(struct stat *st) _pure_;
 int null_or_empty_path(const char *fn);
+int null_or_empty_fd(int fd);
 
 int execute_command(const char *command, char *const argv[]);