[PATCH 05/11] kselftest/arm64: mte: common: Fix write() warnings

[Andre Przywara]

Out of the box Ubuntu's 20.04 compiler warns about missing return value
checks for write() (sys)calls.

Make GCC happy by checking whether we actually managed to write out our
buffer.

Reviewed-by: Andre Przywara <andre.przywara at arm.com>
---
 .../selftests/arm64/mte/mte_common_util.c     | 23 +++++++++++++++----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/arm64/mte/mte_common_util.c b/tools/testing/selftests/arm64/mte/mte_common_util.c
index 39f8908988ea..4e887dad762d 100644
--- a/tools/testing/selftests/arm64/mte/mte_common_util.c
+++ b/tools/testing/selftests/arm64/mte/mte_common_util.c
@@ -181,10 +181,17 @@ void *mte_allocate_file_memory(size_t size, int mem_type, int mapping, bool tags
 	}
 	/* Initialize the file for mappable size */
 	lseek(fd, 0, SEEK_SET);
-	for (index = INIT_BUFFER_SIZE; index < size; index += INIT_BUFFER_SIZE)
-		write(fd, buffer, INIT_BUFFER_SIZE);
+	for (index = INIT_BUFFER_SIZE; index < size; index += INIT_BUFFER_SIZE) {
+		if (write(fd, buffer, INIT_BUFFER_SIZE) != INIT_BUFFER_SIZE) {
+			perror("initialising buffer");
+			return NULL;
+		}
+	}
 	index -= INIT_BUFFER_SIZE;
-	write(fd, buffer, size - index);
+	if (write(fd, buffer, size - index) != size - index) {
+		perror("initialising buffer");
+		return NULL;
+	}
 	return __mte_allocate_memory_range(size, mem_type, mapping, 0, 0, tags, fd);
 }
 
@@ -202,9 +209,15 @@ void *mte_allocate_file_memory_tag_range(size_t size, int mem_type, int mapping,
 	/* Initialize the file for mappable size */
 	lseek(fd, 0, SEEK_SET);
 	for (index = INIT_BUFFER_SIZE; index < map_size; index += INIT_BUFFER_SIZE)
-		write(fd, buffer, INIT_BUFFER_SIZE);
+		if (write(fd, buffer, INIT_BUFFER_SIZE) != INIT_BUFFER_SIZE) {
+			perror("initialising buffer");
+			return NULL;
+		}
 	index -= INIT_BUFFER_SIZE;
-	write(fd, buffer, map_size - index);
+	if (write(fd, buffer, map_size - index) != map_size - index) {
+		perror("initialising buffer");
+		return NULL;
+	}
 	return __mte_allocate_memory_range(size, mem_type, mapping, range_before,
 					   range_after, true, fd);
 }
-- 
2.17.5