config: avoid "write_in_full(fd, buf, len) != len" pattern

As explained in commit 06f46f2 (avoid "write_in_full(fd, buf, len)
!= len" pattern, 2017–09–13) the return value of write_in_full() is
either -1 or the requested number of bytes. As such comparing the
return value to an unsigned value such as strbuf.len will fail to
catch errors. Change the code to use the preferred '< 0' check.

Signed-off-by: Phillip Wood <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: phillipwood

config.c

@@ -2700,7 +2700,7 @@ static int git_config_copy_or_rename_section_in_file(const char *config_filename
 			 * multiple [branch "$name"] sections.
 			 */
 			if (copystr.len > 0) {
-				if (write_in_full(out_fd, copystr.buf, copystr.len) != copystr.len) {
+				if (write_in_full(out_fd, copystr.buf, copystr.len) < 0) {
 					ret = write_error(get_lock_file_path(lock));
 					goto out;
 				}
@@ -2763,7 +2763,7 @@ static int git_config_copy_or_rename_section_in_file(const char *config_filename
 	 * logic in the loop above.
 	 */
 	if (copystr.len > 0) {
-		if (write_in_full(out_fd, copystr.buf, copystr.len) != copystr.len) {
+		if (write_in_full(out_fd, copystr.buf, copystr.len) < 0) {
 			ret = write_error(get_lock_file_path(lock));
 			goto out;
 		}