convert less-trivial versions of "write_in_full() != len"

The prior commit converted many sites to check the return
value of write_in_full() for negativity, rather than a
mismatch with the input length. This patch covers similar
cases, but where the return value is stored in an
intermediate variable. These should get the same treatment,
but they need to be reviewed more carefully since it would
be a bug if the return value is stored in an unsigned type
(which indeed, it is in one of the cases).

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

entry.c

@@ -244,7 +244,8 @@ static int write_entry(struct cache_entry *ce,
 	char *new;
 	struct strbuf buf = STRBUF_INIT;
 	unsigned long size;
-	size_t wrote, newsize = 0;
+	ssize_t wrote;
+	size_t newsize = 0;
 	struct stat st;
 	const struct submodule *sub;
 
@@ -319,7 +320,7 @@ static int write_entry(struct cache_entry *ce,
 			fstat_done = fstat_output(fd, state, &st);
 		close(fd);
 		free(new);
-		if (wrote != size)
+		if (wrote < 0)
 			return error("unable to write file %s", path);
 		break;
 	case S_IFGITLINK:

refs/files-backend.c

@@ -2039,7 +2039,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
 
 	written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
 	free(logrec);
-	if (written != len)
+	if (written < 0)
 		return -1;
 
 	return 0;

streaming.c

@@ -539,7 +539,7 @@ int stream_blob_to_fd(int fd, const struct object_id *oid, struct stream_filter
 			kept = 0;
 		wrote = write_in_full(fd, buf, readlen);
 
-		if (wrote != readlen)
+		if (wrote < 0)
 			goto close_and_exit;
 	}
 	if (kept && (lseek(fd, kept - 1, SEEK_CUR) == (off_t) -1 ||