[hackers] [ubase] dd: truncate file when using seek= || Eivind Uggedal

[git]

commit 596663c1b1f140c10ba1facede783201d6a876a7
Author:     Eivind Uggedal <eiv...@uggedal.com>
AuthorDate: Tue Mar 15 21:06:28 2016 +0000
Commit:     sin <s...@2f30.org>
CommitDate: Wed Mar 16 10:17:51 2016 +0000

    dd: truncate file when using seek=

diff --git a/dd.c b/dd.c
index daa75fd..912ca83 100644
--- a/dd.c
+++ b/dd.c
@@ -108,6 +108,15 @@ prepare_copy(struct dd_config *ddc, int *ifd, int *ofd)
                return -1;
        }
 
+       if (ddc->seek) {
+               if (fstat(*ofd, &st) < 0)
+                       return -1;
+               if (!S_ISREG(st.st_mode))
+                       ;
+               else if (ftruncate(*ofd, ddc->seek) < 0)
+                       return -1;
+       }
+
        if (lseek(*ifd, ddc->skip, SEEK_CUR) < 0) {
                char buffer[ddc->bs];
                for (uint64_t i = 0; i < ddc->skip; i += ddc->bs) {