+
+ if (one->sha1_valid &&
+ (!memcmp(one->blob_sha1, null_sha1, sizeof(null_sha1)) ||
+ work_tree_matches(name, one->blob_sha1)))
+ use_work_tree = 1;
+
+ if (!one->sha1_valid || use_work_tree) {
+ struct stat st;
+ temp->name = name;
+ if (lstat(temp->name, &st) < 0) {
+ if (errno == ENOENT)
+ goto not_a_valid_file;
+ die("stat(%s): %s", temp->name, strerror(errno));
+ }
+ if (S_ISLNK(st.st_mode)) {
+ int ret;
+ char *buf, buf_[1024];
+ buf = ((sizeof(buf_) < st.st_size) ?
+ xmalloc(st.st_size) : buf_);
+ ret = readlink(name, buf, st.st_size);
+ if (ret < 0)
+ die("readlink(%s)", name);
+ prep_temp_blob(temp, buf, st.st_size,
+ (one->sha1_valid ?
+ one->blob_sha1 : null_sha1),
+ (one->sha1_valid ?
+ one->mode : S_IFLNK));
+ }
+ else {
+ if (!one->sha1_valid)
+ strcpy(temp->hex, sha1_to_hex(null_sha1));
+ else
+ strcpy(temp->hex, sha1_to_hex(one->blob_sha1));
+ sprintf(temp->mode, "%06o",
+ S_IFREG |ce_permissions(st.st_mode));
+ }
+ return;
+ }
+ else {
+ void *blob;
+ char type[20];
+ unsigned long size;
+
+ blob = read_sha1_file(one->blob_sha1, type, &size);
+ if (!blob || strcmp(type, "blob"))
+ die("unable to read blob object for %s (%s)",
+ name, sha1_to_hex(one->blob_sha1));
+ prep_temp_blob(temp, blob, size, one->blob_sha1, one->mode);
+ free(blob);
+ }
+}
+
+static void remove_tempfile(void)
+{
+ int i;
+
+ for (i = 0; i < 2; i++)
+ if (diff_temp[i].name == diff_temp[i].tmp_path) {
+ unlink(diff_temp[i].name);
+ diff_temp[i].name = NULL;
+ }
+}
+
+static void remove_tempfile_on_signal(int signo)
+{
+ remove_tempfile();
+}
+
+/* An external diff command takes:
+ *
+ * diff-cmd name infile1 infile1-sha1 infile1-mode \
+ * infile2 infile2-sha1 infile2-mode.
+ *
+ */
+void run_external_diff(const char *name,
+ struct diff_spec *one,
+ struct diff_spec *two)
+{
+ struct diff_tempfile *temp = diff_temp;
+ pid_t pid;
+ int status;
+ static int atexit_asked = 0;
+
+ if (one && two) {
+ prepare_temp_file(name, &temp[0], one);
+ prepare_temp_file(name, &temp[1], two);
+ if (! atexit_asked &&
+ (temp[0].name == temp[0].tmp_path ||
+ temp[1].name == temp[1].tmp_path)) {
+ atexit_asked = 1;
+ atexit(remove_tempfile);
+ }
+ signal(SIGINT, remove_tempfile_on_signal);
+ }
+
+ fflush(NULL);
+ pid = fork();
+ if (pid < 0)
+ die("unable to fork");
+ if (!pid) {
+ const char *pgm = external_diff();
+ if (pgm) {
+ if (one && two)
+ execlp(pgm, pgm,
+ name,
+ temp[0].name, temp[0].hex, temp[0].mode,
+ temp[1].name, temp[1].hex, temp[1].mode,
+ NULL);
+ else
+ execlp(pgm, pgm, name, NULL);
+ }
+ /*
+ * otherwise we use the built-in one.
+ */
+ if (one && two)
+ builtin_diff(name, temp);
+ else
+ printf("* Unmerged path %s\n", name);
+ exit(0);
+ }
+ if (waitpid(pid, &status, 0) < 0 ||
+ !WIFEXITED(status) || WEXITSTATUS(status)) {
+ /* Earlier we did not check the exit status because
+ * diff exits non-zero if files are different, and
+ * we are not interested in knowing that. It was a
+ * mistake which made it harder to quit a diff-*
+ * session that uses the git-apply-patch-script as
+ * the GIT_EXTERNAL_DIFF. A custom GIT_EXTERNAL_DIFF
+ * should also exit non-zero only when it wants to
+ * abort the entire diff-* session.
+ */
+ remove_tempfile();
+ fprintf(stderr, "external diff died, stopping at %s.\n", name);
+ exit(1);
+ }
+ remove_tempfile();
+}
+
+void diff_addremove(int addremove, unsigned mode,
+ const unsigned char *sha1,
+ const char *base, const char *path)
+{
+ char concatpath[PATH_MAX];
+ struct diff_spec spec[2], *one, *two;
+
+ memcpy(spec[0].blob_sha1, sha1, 20);
+ spec[0].mode = mode;
+ spec[0].sha1_valid = spec[0].file_valid = 1;
+ spec[1].file_valid = 0;
+
+ if (addremove == '+') {
+ one = spec + 1; two = spec;
+ } else {
+ one = spec; two = one + 1;
+ }
+
+ if (path) {
+ strcpy(concatpath, base);
+ strcat(concatpath, path);
+ }
+ run_external_diff(path ? concatpath : base, one, two);
+}
+
+void diff_change(unsigned old_mode, unsigned new_mode,
+ const unsigned char *old_sha1,
+ const unsigned char *new_sha1,
+ const char *base, const char *path) {
+ char concatpath[PATH_MAX];
+ struct diff_spec spec[2];
+
+ memcpy(spec[0].blob_sha1, old_sha1, 20);
+ spec[0].mode = old_mode;
+ memcpy(spec[1].blob_sha1, new_sha1, 20);
+ spec[1].mode = new_mode;
+ spec[0].sha1_valid = spec[0].file_valid = 1;
+ spec[1].sha1_valid = spec[1].file_valid = 1;
+
+ if (path) {
+ strcpy(concatpath, base);
+ strcat(concatpath, path);
+ }
+ run_external_diff(path ? concatpath : base, &spec[0], &spec[1]);
+}
+
+void diff_unmerge(const char *path)
+{
+ run_external_diff(path, NULL, NULL);