include: add close_fd() for noticing write errors before close()

Essentially this helper function is similar to close_stream(), but for
file descriptors.

When a file descriptors are close()'d status of write is often
overlooked.  The close_fd() will try to determine what happen to writes
with fsync() before closing the file descriptor.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

diff --git a/include/closestream.h b/include/closestream.h
index d61b83b5ec4c7da22abad642d3612943940000d8..2535c8b22eb1cbc8b8c76d31297e50b2421ba465 100644 (file)
--- a/include/closestream.h
+++ b/include/closestream.h
@@ -48,4 +48,23 @@ close_stdout(void)
                _exit(EXIT_FAILURE);
 }
 
+#ifndef HAVE_FSYNC
+static inline int
+fsync(int fd __attribute__((__unused__)))
+{
+       return 0;
+}
+#endif
+
+static inline int
+close_fd(int fd)
+{
+       const int fsync_fail = (fsync(fd) != 0);
+       const int close_fail = (close(fd) != 0);
+
+       if (fsync_fail || close_fail)
+               return EOF;
+       return 0;
+}
+
 #endif /* UTIL_LINUX_CLOSESTREAM_H */