patch unveil fail

[Alexander Bluhm]

Hi,

Since 7.4 patch(1) does not work if an explicit patchfile is given on
command line.

https://marc.info/?l=openbsd-cvs&m=168941770509379&w=2

root@ot14:.../~# patch /usr/src/usr.bin/patch/patch.c patch-unveil.diff
Hmm...  Looks like a unified diff to me...
The text leading up to this was:
--------------------------
|Index: patch.c
|===================================================================
|RCS file: /data/mirror/openbsd/cvs/src/usr.bin/patch/patch.c,v
|diff -u -p -r1.74 patch.c
|--- patch.c    19 Jul 2023 13:26:20 -0000      1.74
|+++ patch.c    24 Oct 2023 17:13:28 -0000
--------------------------
Patching file /usr/src/usr.bin/patch/patch.c using Plan A...
Hunk #1 succeeded at 32.
Hunk #2 succeeded at 214.
Hunk #3 succeeded at 245.
Can't backup /usr/src/usr.bin/patch/patch.c, output is in 
/tmp/patchoorjYymLKcM: No such file or directory
done

A backup file should be created in the directory of the original
file, but only the current directory is unveiled.  Then the patched
file is created in /tmp and does not replace the original patchfile
in place.

Diff below fixes it.

ok?

bluhm

Index: patch.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/usr.bin/patch/patch.c,v
diff -u -p -r1.74 patch.c
--- patch.c     19 Jul 2023 13:26:20 -0000      1.74
+++ patch.c     24 Oct 2023 17:13:28 -0000
@@ -32,6 +32,7 @@
 
 #include <ctype.h>
 #include <getopt.h>
+#include <libgen.h>
 #include <limits.h>
 #include <paths.h>
 #include <stdio.h>
@@ -213,11 +214,27 @@ main(int argc, char *argv[])
                        perror("unveil");
                        my_exit(2);
                }
-       if (filearg[0] != NULL)
+       if (filearg[0] != NULL) {
+               char *origdir;
+
                if (unveil(filearg[0], "rwc") == -1) {
                        perror("unveil");
                        my_exit(2);
                }
+               if ((origdir = dirname(filearg[0])) == NULL) {
+                       perror("dirname");
+                       my_exit(2);
+               }
+               if (unveil(origdir, "rwc") == -1) {
+                       perror("unveil");
+                       my_exit(2);
+               }
+       } else {
+               if (unveil(".", "rwc") == -1) {
+                       perror("unveil");
+                       my_exit(2);
+               }
+       }
        if (filearg[1] != NULL)
                if (unveil(filearg[1], "r") == -1) {
                        perror("unveil");
@@ -228,10 +245,6 @@ main(int argc, char *argv[])
                        perror("unveil");
                        my_exit(2);
                }
-       if (unveil(".", "rwc") == -1) {
-               perror("unveil");
-               my_exit(2);
-       }
        if (*rejname != '\0')
                if (unveil(rejname, "rwc") == -1) {
                        perror("unveil");