Re: [PATCH/WIP v3 04/31] am: implement patch queue mechanism

+ * about the file size, to avoid reallocs. Returns number of bytes read on
+ * success, -1 if the file does not exist. If trim is set, trailing whitespace
+ * will be removed from the file contents.
+ */
+static int read_state_file(struct strbuf *sb, const char *file, size_t hint, int trim)
+{
+       strbuf_reset(sb);
+       if (strbuf_read_file(sb, file, hint) >= 0) {
+               if (trim)
+                       strbuf_trim(sb);
+
+               return sb->len;
+       }
+
+       if (errno == ENOENT)
+               return -1;
+
+       die_errno(_("could not read '%s'"), file);
+}
+
+/**
+ * Loads state from disk.
+ */
+static void am_load(struct am_state *state)
+{
+       struct strbuf sb = STRBUF_INIT;
+
+       read_state_file(&sb, am_path(state, "next"), 8, 1);
+       state->cur = strtol(sb.buf, NULL, 10);
+
+       read_state_file(&sb, am_path(state, "last"), 8, 1);
+       state->last = strtol(sb.buf, NULL, 10);
+
+       strbuf_release(&sb);
+}
+
+/**
+ * Remove the am_state directory.
+ */
+static void am_destroy(const struct am_state *state)
+{
+       struct strbuf sb = STRBUF_INIT;
+
+       strbuf_addstr(&sb, state->dir.buf);
+       remove_dir_recursively(&sb, 0);
+       strbuf_release(&sb);
+}
+
+/**
+ * Setup a new am session for applying patches
+ */
+static void am_setup(struct am_state *state)
+{
+       if (mkdir(state->dir.buf, 0777) < 0 && errno != EEXIST)
+               die_errno(_("failed to create directory '%s'"), state->dir.buf);
+
+       write_file(am_path(state, "next"), 1, "%d", state->cur);
+
+       write_file(am_path(state, "last"), 1, "%d", state->last);
+}
+
+/**
+ * Increments the patch pointer, and cleans am_state for the application of the
+ * next patch.
+ */
+static void am_next(struct am_state *state)
+{
+       state->cur++;
+       write_file(am_path(state, "next"), 1, "%d", state->cur);
+}
+
+/**
+ * Applies all queued patches.
+ */
+static void am_run(struct am_state *state)
+{
+       while (state->cur <= state->last) {
+
+               /* TODO: Patch application not implemented yet */
+
+               am_next(state);
+       }
+
+       am_destroy(state);
+}
+
+static struct am_state state;
+
+static const char * const am_usage[] = {
+       N_("git am [options] [(<mbox>|<Maildir>)...]"),
+       NULL
+};
+
+static struct option am_options[] = {
+       OPT_END()
+};

 int cmd_am(int argc, const char **argv, const char *prefix)
 {

@@ -24,5 +176,21 @@ int cmd_am(int argc, const char **argv, const char *prefix)
                setup_work_tree();
        }

+       git_config(git_default_config, NULL);
+
+       am_state_init(&state);
+       strbuf_addstr(&state.dir, git_path("rebase-apply"));
+
+       argc = parse_options(argc, argv, prefix, am_options, am_usage, 0);
+
+       if (am_in_progress(&state))
+               am_load(&state);
+       else
+               am_setup(&state);
+
+       am_run(&state);
+
+       am_state_release(&state);
+
        return 0;
 }
--

2.1.4