udev: always close lock file descriptor

https://bugs.freedesktop.org/show_bug.cgi?id=79576

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

2 files changed, 26 insertions, 0 deletions

diff --git a/src/libudev/util.c b/src/libudev/util.c
index 4796505a5c..cfdf848cce 100644
--- a/src/libudev/util.c
+++ b/src/libudev/util.c
@@ -154,6 +154,30 @@ void close_nointr_nofail(int fd) {
         assert_se(close_nointr(fd) == 0);
 }
 
+int safe_close(int fd) {
+
+        /*
+         * Like close_nointr() but cannot fail. Guarantees errno is
+         * unchanged. Is a NOP with negative fds passed, and returns
+         * -1, so that it can be used in this syntax:
+         *
+         * fd = safe_close(fd);
+         */
+
+        if (fd >= 0) {
+                PROTECT_ERRNO;
+
+                /* The kernel might return pretty much any error code
+                 * via close(), but the fd will be closed anyway. The
+                 * only condition we want to check for here is whether
+                 * the fd was invalid at all... */
+
+                assert_se(close_nointr(fd) != -EBADF);
+        }
+
+        return -1;
+}
+
 int unlink_noerrno(const char *path) {
         PROTECT_ERRNO;
         int r;
diff --git a/src/libudev/util.h b/src/libudev/util.h
index a950f2658f..332dfb6207 100644
--- a/src/libudev/util.h
+++ b/src/libudev/util.h
@@ -124,6 +124,8 @@ static inline const char *startswith(const char *s, const char *prefix) {
 char *endswith(const char *s, const char *postfix) _pure_;
 
 int close_nointr(int fd);
+int safe_close(int fd);
+
 void close_nointr_nofail(int fd);
 
 int safe_atou(const char *s, unsigned *ret_u);