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.

2 files changed, 12 insertions, 0 deletions

diff --git a/src/shared/util.c b/src/shared/util.c
index 75dc58b63d..4fda31c838 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -3604,6 +3604,17 @@ 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);
+}
+
 DIR *xopendirat(int fd, const char *name, int flags) {
         int nfd;
         DIR *d;
diff --git a/src/shared/util.h b/src/shared/util.h
index b3187a9ea1..d9d525e8a5 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -499,6 +499,7 @@ noreturn void freeze(void);
 
 bool null_or_empty(struct stat *st) _pure_;
 int null_or_empty_path(const char *fn);
+int null_or_empty_fd(int fd);
 
 DIR *xopendirat(int dirfd, const char *name, int flags);