Hi,
patch will fail with a segmentation fault in "plan a" if it encounters a
diff with a revision (Prereq line) when the input file is empty.
i_womp will be set to NULL to avoid mmapping 0 bytes, but later on it
will be scanned for the supplied revision.
The fix is simple: avoid scanning i_womp if it's NULL. Just enter the
if-condition that the revision is not in there.
How to reproduce:
$ echo a > a
$ echo b > b
$ diff -u a b | sed '3i\
> Prereq: 1\
> ' > b.diff
$ cat b.diff
--- a Mon Nov 24 16:31:24 2014
+++ b Mon Nov 24 16:31:26 2014
Prereq: 1
@@ -1 +1 @@
-a
+b
$ rm a b; touch a b;
$ patch -i b.diff
Hmm... Looks like a unified diff to me...
The text leading up to this was:
--------------------------
|--- a Mon Nov 24 16:31:24 2014
|+++ b Mon Nov 24 16:31:26 2014
|Prereq: 1
--------------------------
Segmentation fault (core dumped)
Tobias
Index: inp.c
===================================================================
RCS file: /cvs/src/usr.bin/patch/inp.c,v
retrieving revision 1.40
diff -u -p -r1.40 inp.c
--- inp.c 22 Nov 2014 15:49:28 -0000 1.40
+++ inp.c 24 Nov 2014 15:36:37 -0000
@@ -303,7 +303,7 @@ plan_a(const char *filename)
/* now check for revision, if any */
if (revision != NULL) {
- if (!rev_in_string(i_womp)) {
+ if (i_womp == NULL || !rev_in_string(i_womp)) {
if (force) {
if (verbose)
say("Warning: this file doesn't appear "
