util: add a bit of syntactic sugar for saving/restoring errno

3 files changed, 15 insertions, 26 deletions

diff --git a/src/shared/log.c b/src/shared/log.c
index 293c261f9e..0dd04bc51e 100644
--- a/src/shared/log.c
+++ b/src/shared/log.c
@@ -598,18 +598,14 @@ int log_dump_internal(
         const char *func,
         char *buffer) {
 
-        int saved_errno, r;
+        PROTECT_ERRNO;
 
         /* This modifies the buffer... */
 
         if (_likely_(LOG_PRI(level) > log_max_level))
                 return 0;
 
-        saved_errno = errno;
-        r = log_dispatch(level, file, line, func, NULL, NULL, buffer);
-        errno = saved_errno;
-
-        return r;
+        return log_dispatch(level, file, line, func, NULL, NULL, buffer);
 }
 
 int log_metav(
@@ -620,20 +616,16 @@ int log_metav(
         const char *format,
         va_list ap) {
 
+        PROTECT_ERRNO;
         char buffer[LINE_MAX];
-        int saved_errno, r;
 
         if (_likely_(LOG_PRI(level) > log_max_level))
                 return 0;
 
-        saved_errno = errno;
         vsnprintf(buffer, sizeof(buffer), format, ap);
         char_array_0(buffer);
 
-        r = log_dispatch(level, file, line, func, NULL, NULL, buffer);
-        errno = saved_errno;
-
-        return r;
+        return log_dispatch(level, file, line, func, NULL, NULL, buffer);
 }
 
 int log_meta(
@@ -663,21 +655,17 @@ int log_metav_object(
         const char *format,
         va_list ap) {
 
+        PROTECT_ERRNO;
         char buffer[LINE_MAX];
-        int saved_errno, r;
 
         if (_likely_(LOG_PRI(level) > log_max_level))
                 return 0;
 
-        saved_errno = errno;
         vsnprintf(buffer, sizeof(buffer), format, ap);
         char_array_0(buffer);
 
-        r = log_dispatch(level, file, line, func,
-                         object_name, object, buffer);
-        errno = saved_errno;
-
-        return r;
+        return log_dispatch(level, file, line, func,
+                            object_name, object, buffer);
 }
 
 int log_meta_object(
@@ -735,7 +723,7 @@ int log_struct_internal(
                 const char *func,
                 const char *format, ...) {
 
-        int saved_errno;
+        PROTECT_ERRNO;
         va_list ap;
         int r;
 
@@ -748,8 +736,6 @@ int log_struct_internal(
         if ((level & LOG_FACMASK) == 0)
                 level = log_facility | LOG_PRI(level);
 
-        saved_errno = errno;
-
         if ((log_target == LOG_TARGET_AUTO ||
              log_target == LOG_TARGET_JOURNAL_OR_KMSG ||
              log_target == LOG_TARGET_JOURNAL) &&
@@ -843,7 +829,6 @@ int log_struct_internal(
                         r = -EINVAL;
         }
 
-        errno = saved_errno;
         return r;
 }
 
diff --git a/src/shared/util.c b/src/shared/util.c
index 46c20bec9c..b69e7e882a 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -207,14 +207,12 @@ int close_nointr(int fd) {
 }
 
 void close_nointr_nofail(int fd) {
-        int saved_errno = errno;
+        PROTECT_ERRNO;
 
         /* like close_nointr() but cannot fail, and guarantees errno
          * is unchanged */
 
         assert_se(close_nointr(fd) == 0);
-
-        errno = saved_errno;
 }
 
 void close_many(const int fds[], unsigned n_fd) {
diff --git a/src/shared/util.h b/src/shared/util.h
index d1cdd901a0..7f050758a0 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -615,3 +615,9 @@ char *strextend(char **x, ...);
 char *strrep(const char *s, unsigned n);
 
 void* greedy_realloc(void **p, size_t *allocated, size_t need);
+
+static inline void reset_errno(int *saved_errno) {
+        errno = *saved_errno;
+}
+
+#define PROTECT_ERRNO __attribute__((cleanup(reset_errno))) int _saved_errno_ = errno