diff: change handling of temporary files for WIN32

If it isn't possible to seek in an input file diff creates a temporary
file to store the text.

On Windows we can't assume that /tmp exists and we need to unlink
the temporary files at the end of processing, not the start.

1 files changed, 21 insertions, 0 deletions

diff --git a/editors/diff.c b/editors/diff.c
index 75229ad8c..5c8a55b93 100644
--- a/editors/diff.c
+++ b/editors/diff.c
@@ -724,6 +724,10 @@ static int diffreg(char *file[2])
         FILE *fp[2];
         bool binary = false, differ = false;
         int status = STATUS_SAME, i;
+#if ENABLE_PLATFORM_MINGW32
+        char *tmpfile[2] = { NULL, NULL };
+        char *tmpdir;
+#endif
 
         fp[0] = stdin;
         fp[1] = stdin;
@@ -735,10 +739,19 @@ static int diffreg(char *file[2])
                  * When we meet non-seekable file, we must make a temp copy.
                  */
                 if (lseek(fd, 0, SEEK_SET) == -1 && errno == ESPIPE) {
+#if !ENABLE_PLATFORM_MINGW32
                         char name[] = "/tmp/difXXXXXX";
                         int fd_tmp = xmkstemp(name);
 
                         unlink(name);
+#else
+                        int fd_tmp;
+
+                        if (!(tmpdir=getenv("TMP")) && !(tmpdir=getenv("TEMP")))
+                                goto out;
+                        tmpfile[i] = xasprintf("%s/difXXXXXX", tmpdir);
+                        fd_tmp = xmkstemp(tmpfile[i]);
+#endif
                         if (bb_copyfd_eof(fd, fd_tmp) < 0)
                                 xfunc_die();
                         if (fd != STDIN_FILENO)
@@ -781,6 +794,14 @@ static int diffreg(char *file[2])
 out:
         fclose_if_not_stdin(fp[0]);
         fclose_if_not_stdin(fp[1]);
+#if ENABLE_PLATFORM_MINGW32
+        for (i = 0; i < 2; i++) {
+                if (tmpfile[i]) {
+                        unlink(tmpfile[i]);
+                        free(tmpfile[i]);
+                }
+        }
+#endif
 
         return status;
 }