dd: fix handling of short result of full_write(), closes 11711
$ dd bs=1G <sda1 of=/dev/sda1
dd: error writing '/dev/sda1': No space left on device
1+0 records in
0+0 records out
999292928 bytes (953.0MB) copied, 0.784617 seconds, 1.2GB/s
function old new delta
write_and_stats 99 102 +3
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/coreutils/dd.c b/coreutils/dd.c
index 2fb9da7..b5f3cbe 100644
--- a/coreutils/dd.c
+++ b/coreutils/dd.c
@@ -192,23 +192,15 @@
#endif
}
-static ssize_t full_write_or_warn(const void *buf, size_t len,
- const char *const filename)
-{
- ssize_t n = full_write(ofd, buf, len);
- if (n < 0)
- bb_perror_msg("writing '%s'", filename);
- return n;
-}
-
static bool write_and_stats(const void *buf, size_t len, size_t obs,
const char *filename)
{
- ssize_t n = full_write_or_warn(buf, len, filename);
- if (n < 0)
- return 1;
+ ssize_t n;
+
+ n = full_write(ofd, buf, len);
#if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
- G.total_bytes += n;
+ if (n > 0)
+ G.total_bytes += n;
#endif
if ((size_t)n == obs) {
G.out_full++;
@@ -218,6 +210,14 @@
G.out_part++;
return 0;
}
+ /* n is < len (and possibly is -1).
+ * Even if n >= 0, errno is usually set correctly.
+ * For example, if writing to block device and getting ENOSPC,
+ * full_write() first sees a short write, then tries to write
+ * the remainder and gets errno set to ENOSPC.
+ * It returns n > 0 (the amount which it did write).
+ */
+ bb_perror_msg("error writing '%s'", filename);
return 1;
}
diff --git a/libbb/full_write.c b/libbb/full_write.c
index 2b7983f..15766fc 100644
--- a/libbb/full_write.c
+++ b/libbb/full_write.c
@@ -11,7 +11,8 @@
/*
* Write all of the supplied buffer out to a file.
* This does multiple writes as necessary.
- * Returns the amount written, or -1 on an error.
+ * Returns the amount written, or -1 if error was seen
+ * on the very first write.
*/
ssize_t FAST_FUNC full_write(int fd, const void *buf, size_t len)
{
