aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--toys/pending/dd.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/toys/pending/dd.c b/toys/pending/dd.c
index 7de91825..a7b7f5fd 100644
--- a/toys/pending/dd.c
+++ b/toys/pending/dd.c
@@ -224,7 +224,12 @@ void dd_main()
if (!(TT.oflag & _DD_oflag_seek_bytes)) bs *= TT.out.sz;
if (bs) {
xlseek(TT.out.fd, bs, SEEK_CUR);
- if (trunc && ftruncate(TT.out.fd, bs)) perror_exit("ftruncate");
+ if (trunc && ftruncate(TT.out.fd, bs)) {
+ struct stat st;
+ if (fstat(TT.out.fd, &st) < 0 || S_ISREG(st.st_mode) || S_ISDIR(st.st_mode)) {
+ perror_exit("unexpected ftruncate failure");
+ }
+ }
}
unsigned long long bytes_left = TT.c_count;