Add poor man's "show most recent tag" by using git-describe

In the diff view, the "Refs:" lines will now sport the output of
git-describe by appending it as the last reference to the line.

Now, it should probably be optional and I mostly added it because I wanted
to do a little tig hacking. Anyway, let's hope it will be useful.

diff --git a/tig.c b/tig.c
index 08cdd41..97e3d0d 100644 (file)
--- a/tig.c
+++ b/tig.c
@@ -2067,6 +2067,34 @@ pager_draw(struct view *view, struct line *line, unsigned int lineno)
        return TRUE;
 }
 
+static bool
+add_describe_ref(char *buf, int *bufpos, char *commit_id, const char *sep)
+{
+       char refbuf[1024];
+       char *ref = NULL;
+       FILE *pipe;
+
+       if (!string_format(refbuf, "git describe %s", commit_id))
+               return TRUE;
+
+       pipe = popen(refbuf, "r");
+       if (!pipe)
+               return TRUE;
+
+       if ((ref = fgets(refbuf, sizeof(refbuf), pipe)))
+               ref = chomp_string(ref);
+       pclose(pipe);
+
+       if (!ref || !*ref)
+               return TRUE;
+
+       /* This is the only fatal call, since it can "corrupt" the buffer. */
+       if (!string_nformat(buf, 1024, bufpos, "%s%s", sep, ref))
+               return FALSE;
+
+       return TRUE;
+}
+
 static void
 add_pager_refs(struct view *view, struct line *line)
 {
@@ -2075,12 +2103,16 @@ add_pager_refs(struct view *view, struct line *line)
        struct ref **refs;
        int bufpos = 0, refpos = 0;
        const char *sep = "Refs: ";
+       bool is_tag = FALSE;
 
        assert(line->type == LINE_COMMIT);
 
        refs = get_refs(commit_id);
-       if (!refs)
+       if (!refs) {
+               if (view == VIEW(REQ_VIEW_DIFF))
+                       goto try_add_describe_ref;
                return;
+       }
 
        do {
                struct ref *ref = refs[refpos];
@@ -2089,8 +2121,16 @@ add_pager_refs(struct view *view, struct line *line)
                if (!string_format_from(buf, &bufpos, fmt, sep, ref->name))
                        return;
                sep = ", ";
+               if (ref->tag)
+                       is_tag = TRUE;
        } while (refs[refpos++]->next);
 
+       if (!is_tag && view == VIEW(REQ_VIEW_DIFF)) {
+try_add_describe_ref:
+               if (!add_describe_ref(buf, &bufpos, commit_id, sep))
+                       return;
+       }
+
        if (!realloc_lines(view, view->line_size + 1))
                return;