fseek() with SEEK_SET is broken on large file capable 32-bit systems, so

revert to the SEEK_END method of repositioning the stream after a ftruncate()
and only use SEEK_SET if ftruncate() isn't available.

1 files changed, 9 insertions, 3 deletions

diff --git a/src/main.c b/src/main.c
index 43e9c4939..2d80e726f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -3773,10 +3773,16 @@ operate(struct Configurable *config, int argc, char *argv[])
                 /* truncate file at the position where we started appending */
 #ifdef HAVE_FTRUNCATE
                 ftruncate( fileno(outs.stream), outs.init);
-#endif
                 /* now seek to the end of the file, the position where we
-                   just truncated the file */
-                fseek(outs.stream, outs.init, SEEK_SET);
+                   just truncated the file in a large file-safe way */
+                fseek(outs.stream, 0, SEEK_END);
+#else
+                /* ftruncate is not available, so just reposition the file
+                   to the location we would have truncated it. This won't
+                   work properly with large files on 32-bit systems, but
+                   most of those will have ftruncate. */
+                fseek(outs.stream, (long)outs.init, SEEK_SET);
+#endif
                 outs.bytes = 0; /* clear for next round */
               }
               continue;