[LTP] [PATCH v2 13/15] ujson: writer: Set errno when a flush fails

[Andrea Cervesato]

From: Andrea Cervesato <andrea.cervesato@suse.com>

ujson_writer_file_close() uses errno to decide whether flushing the
buffered data failed. out_writer_file_write() can fail without setting
errno, when write() returns 0 or more bytes than requested, so close
could report success even though data was lost. Set errno to EAGAIN or
EIO in these cases.

Fixes: c50a0e0751c8 ("libs: Vendor ujson library")
Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
---
 libs/ujson/ujson_writer.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/libs/ujson/ujson_writer.c b/libs/ujson/ujson_writer.c
index 7882a5ab5..eb446749f 100644
--- a/libs/ujson/ujson_writer.c
+++ b/libs/ujson/ujson_writer.c
@@ -404,13 +404,20 @@ static int out_writer_file_write(ujson_writer *self, int fd, const char *buf, ss
 {
 	do {
 		ssize_t ret = write(fd, buf, buf_len);
-		if (ret <= 0) {
+		if (ret < 0) {
 			err(self, "Failed to write to a file");
 			return 1;
 		}
 
+		if (ret == 0) {
+			err(self, "The write() syscall returned 0");
+			errno = EAGAIN;
+			return 1;
+		}
+
 		if (ret > buf_len) {
 			err(self, "Wrote more bytes than requested?!");
+			errno = EIO;
 			return 1;
 		}
 

-- 
2.51.0