Merge branch 'pb/prepare-commit-msg'

* pb/prepare-commit-msg:
  git-commit: add a prepare-commit-msg hook
  git-commit: Refactor creation of log message.
  git-commit: set GIT_EDITOR=: if editor will not be launched
  git-commit: support variable number of hook arguments

diff --combined builtin-commit.c
index ff6ea0d85eebdd0b815f33b9b1ef0df8d1885988,03caa30f0e4232bb613f70a04fa2914385e2cd6f..6612b4f40504fea0cd9aec4463c20d8982bfbaeb
--- 1/builtin-commit.c
--- 2/builtin-commit.c
+++ b/builtin-commit.c
@@@ -160,7 -160,7 +160,7 @@@ static int list_paths(struct path_list 
  
        for (i = 0; i < active_nr; i++) {
                struct cache_entry *ce = active_cache[i];
 -              if (ce->ce_flags & htons(CE_UPDATE))
 +              if (ce->ce_flags & CE_UPDATE)
                        continue;
                if (!pathspec_match(pattern, m, ce->name, 0))
                        continue;
@@@ -317,10 -317,6 +317,10 @@@ static char *prepare_index(int argc, co
        if (write_cache(fd, active_cache, active_nr) ||
            close_lock_file(&false_lock))
                die("unable to write temporary index file");
 +
 +      discard_cache();
 +      read_cache_from(false_lock.filename);
 +
        return false_lock.filename;
  }
  
@@@ -347,45 -343,107 +347,107 @@@ static int run_status(FILE *fp, const c
        return s.commitable;
  }
  
+ static int run_hook(const char *index_file, const char *name, ...)
+ {
+       struct child_process hook;
+       const char *argv[10], *env[2];
+       char index[PATH_MAX];
+       va_list args;
+       int i;
+ 
+       va_start(args, name);
+       argv[0] = git_path("hooks/%s", name);
+       i = 0;
+       do {
+               if (++i >= ARRAY_SIZE(argv))
+                       die ("run_hook(): too many arguments");
+               argv[i] = va_arg(args, const char *);
+       } while (argv[i]);
+       va_end(args);
+ 
+       snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
+       env[0] = index;
+       env[1] = NULL;
+ 
+       if (access(argv[0], X_OK) < 0)
+               return 0;
+ 
+       memset(&hook, 0, sizeof(hook));
+       hook.argv = argv;
+       hook.no_stdin = 1;
+       hook.stdout_to_stderr = 1;
+       hook.env = env;
+ 
+       return run_command(&hook);
+ }
+ 
+ static int is_a_merge(const unsigned char *sha1)
+ {
+       struct commit *commit = lookup_commit(sha1);
+       if (!commit || parse_commit(commit))
+               die("could not parse HEAD commit");
+       return !!(commit->parents && commit->parents->next);
+ }
+ 
  static const char sign_off_header[] = "Signed-off-by: ";
  
- static int prepare_log_message(const char *index_file, const char *prefix)
+ static int prepare_to_commit(const char *index_file, const char *prefix)
  {
        struct stat statbuf;
        int commitable, saved_color_setting;
        struct strbuf sb;
        char *buffer;
        FILE *fp;
+       const char *hook_arg1 = NULL;
+       const char *hook_arg2 = NULL;
+ 
+       if (!no_verify && run_hook(index_file, "pre-commit", NULL))
+               return 0;
  
        strbuf_init(&sb, 0);
        if (message.len) {
                strbuf_addbuf(&sb, &message);
+               hook_arg1 = "message";
        } else if (logfile && !strcmp(logfile, "-")) {
                if (isatty(0))
                        fprintf(stderr, "(reading log message from standard input)\n");
                if (strbuf_read(&sb, 0, 0) < 0)
                        die("could not read log from standard input");
+               hook_arg1 = "message";
        } else if (logfile) {
                if (strbuf_read_file(&sb, logfile, 0) < 0)
                        die("could not read log file '%s': %s",
                            logfile, strerror(errno));
+               hook_arg1 = "message";
        } else if (use_message) {
                buffer = strstr(use_message_buffer, "\n\n");
                if (!buffer || buffer[2] == '\0')
                        die("commit has empty message");
                strbuf_add(&sb, buffer + 2, strlen(buffer + 2));
+               hook_arg1 = "commit";
+               hook_arg2 = use_message;
        } else if (!stat(git_path("MERGE_MSG"), &statbuf)) {
                if (strbuf_read_file(&sb, git_path("MERGE_MSG"), 0) < 0)
                        die("could not read MERGE_MSG: %s", strerror(errno));
+               hook_arg1 = "merge";
        } else if (!stat(git_path("SQUASH_MSG"), &statbuf)) {
                if (strbuf_read_file(&sb, git_path("SQUASH_MSG"), 0) < 0)
                        die("could not read SQUASH_MSG: %s", strerror(errno));
+               hook_arg1 = "squash";
        } else if (template_file && !stat(template_file, &statbuf)) {
                if (strbuf_read_file(&sb, template_file, 0) < 0)
                        die("could not read %s: %s",
                            template_file, strerror(errno));
+               hook_arg1 = "template";
        }
  
+       /*
+        * This final case does not modify the template message,
+        * it just sets the argument to the prepare-commit-msg hook.
+        */
+       else if (in_merge)
+               hook_arg1 = "merge";
+ 
        fp = fopen(git_path(commit_editmsg), "w");
        if (fp == NULL)
                die("could not open %s", git_path(commit_editmsg));
@@@ -417,13 -475,38 +479,38 @@@
  
        strbuf_release(&sb);
  
-       if (!use_editor) {
+       if (use_editor) {
+               if (in_merge)
+                       fprintf(fp,
+                               "#\n"
+                               "# It looks like you may be committing a MERGE.\n"
+                               "# If this is not correct, please remove the file\n"
+                               "#      %s\n"
+                               "# and try again.\n"
+                               "#\n",
+                               git_path("MERGE_HEAD"));
+ 
+               fprintf(fp,
+                       "\n"
+                       "# Please enter the commit message for your changes.\n"
+                       "# (Comment lines starting with '#' will ");
+               if (cleanup_mode == CLEANUP_ALL)
+                       fprintf(fp, "not be included)\n");
+               else /* CLEANUP_SPACE, that is. */
+                       fprintf(fp, "be kept.\n"
+                               "# You can remove them yourself if you want to)\n");
+               if (only_include_assumed)
+                       fprintf(fp, "# %s\n", only_include_assumed);
+ 
+               saved_color_setting = wt_status_use_color;
+               wt_status_use_color = 0;
+               commitable = run_status(fp, index_file, prefix, 1);
+               wt_status_use_color = saved_color_setting;
+       } else {
                struct rev_info rev;
                unsigned char sha1[20];
                const char *parent = "HEAD";
  
-               fclose(fp);
- 
                if (!active_nr && read_cache() < 0)
                        die("Cannot read index");
  
@@@ -431,48 -514,60 +518,60 @@@
                        parent = "HEAD^1";
  
                if (get_sha1(parent, sha1))
-                       return !!active_nr;
+                       commitable = !!active_nr;
+               else {
+                       init_revisions(&rev, "");
+                       rev.abbrev = 0;
+                       setup_revisions(0, NULL, &rev, parent);
+                       DIFF_OPT_SET(&rev.diffopt, QUIET);
+                       DIFF_OPT_SET(&rev.diffopt, EXIT_WITH_STATUS);
+                       run_diff_index(&rev, 1 /* cached */);
+ 
+                       commitable = !!DIFF_OPT_TST(&rev.diffopt, HAS_CHANGES);
+               }
+       }
  
-               init_revisions(&rev, "");
-               rev.abbrev = 0;
-               setup_revisions(0, NULL, &rev, parent);
-               DIFF_OPT_SET(&rev.diffopt, QUIET);
-               DIFF_OPT_SET(&rev.diffopt, EXIT_WITH_STATUS);
-               run_diff_index(&rev, 1 /* cached */);
+       fclose(fp);
  
-               return !!DIFF_OPT_TST(&rev.diffopt, HAS_CHANGES);
+       if (!commitable && !in_merge && !allow_empty &&
+           !(amend && is_a_merge(head_sha1))) {
+               run_status(stdout, index_file, prefix, 0);
+               unlink(commit_editmsg);
+               return 0;
        }
  
-       if (in_merge)
-               fprintf(fp,
-                       "#\n"
-                       "# It looks like you may be committing a MERGE.\n"
-                       "# If this is not correct, please remove the file\n"
-                       "#      %s\n"
-                       "# and try again.\n"
-                       "#\n",
-                       git_path("MERGE_HEAD"));
- 
-       fprintf(fp,
-               "\n"
-               "# Please enter the commit message for your changes.\n"
-               "# (Comment lines starting with '#' will ");
-       if (cleanup_mode == CLEANUP_ALL)
-               fprintf(fp, "not be included)\n");
-       else /* CLEANUP_SPACE, that is. */
-               fprintf(fp, "be kept.\n"
-                       "# You can remove them yourself if you want to)\n");
-       if (only_include_assumed)
-               fprintf(fp, "# %s\n", only_include_assumed);
- 
-       saved_color_setting = wt_status_use_color;
-       wt_status_use_color = 0;
-       commitable = run_status(fp, index_file, prefix, 1);
-       wt_status_use_color = saved_color_setting;
+       /*
+        * Re-read the index as pre-commit hook could have updated it,
+        * and write it out as a tree.  We must do this before we invoke
+        * the editor and after we invoke run_status above.
+        */
+       discard_cache();
+       read_cache_from(index_file);
+       if (!active_cache_tree)
+               active_cache_tree = cache_tree();
+       if (cache_tree_update(active_cache_tree,
+                             active_cache, active_nr, 0, 0) < 0) {
+               error("Error building trees");
+               return 0;
+       }
  
-       fclose(fp);
+       if (run_hook(index_file, "prepare-commit-msg",
+                    git_path(commit_editmsg), hook_arg1, hook_arg2, NULL))
+               return 0;
  
-       return commitable;
+       if (use_editor) {
+               char index[PATH_MAX];
+               const char *env[2] = { index, NULL };
+               snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
+               launch_editor(git_path(commit_editmsg), NULL, env);
+       }
+ 
+       if (!no_verify &&
+           run_hook(index_file, "commit-msg", git_path(commit_editmsg), NULL)) {
+               return 0;
+       }
+ 
+       return 1;
  }
  
  /*
@@@ -569,6 -664,8 +668,8 @@@ static int parse_and_validate_options(i
                use_editor = 0;
        if (edit_flag)
                use_editor = 1;
+       if (!use_editor)
+               setenv("GIT_EDITOR", ":", 1);
  
        if (get_sha1("HEAD", head_sha1))
                initial_commit = 1;
@@@ -681,31 -778,6 +782,6 @@@ int cmd_status(int argc, const char **a
        return commitable ? 0 : 1;
  }
  
- static int run_hook(const char *index_file, const char *name, const char *arg)
- {
-       struct child_process hook;
-       const char *argv[3], *env[2];
-       char index[PATH_MAX];
- 
-       argv[0] = git_path("hooks/%s", name);
-       argv[1] = arg;
-       argv[2] = NULL;
-       snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
-       env[0] = index;
-       env[1] = NULL;
- 
-       if (access(argv[0], X_OK) < 0)
-               return 0;
- 
-       memset(&hook, 0, sizeof(hook));
-       hook.argv = argv;
-       hook.no_stdin = 1;
-       hook.stdout_to_stderr = 1;
-       hook.env = env;
- 
-       return run_command(&hook);
- }
- 
  static void print_summary(const char *prefix, const unsigned char *sha1)
  {
        struct rev_info rev;
@@@ -747,8 -819,6 +823,8 @@@
  int git_commit_config(const char *k, const char *v)
  {
        if (!strcmp(k, "commit.template")) {
 +              if (!v)
 +                      return config_error_nonbool(v);
                template_file = xstrdup(v);
                return 0;
        }
@@@ -756,14 -826,6 +832,6 @@@
        return git_status_config(k, v);
  }
  
- static int is_a_merge(const unsigned char *sha1)
- {
-       struct commit *commit = lookup_commit(sha1);
-       if (!commit || parse_commit(commit))
-               die("could not parse HEAD commit");
-       return !!(commit->parents && commit->parents->next);
- }
- 
  static const char commit_utf8_warn[] =
  "Warning: commit message does not conform to UTF-8.\n"
  "You may want to amend it after fixing the message, or set the config\n"
@@@ -795,33 -857,13 +863,13 @@@ int cmd_commit(int argc, const char **a
  
        index_file = prepare_index(argc, argv, prefix);
  
-       if (!no_verify && run_hook(index_file, "pre-commit", NULL)) {
-               rollback_index_files();
-               return 1;
-       }
- 
-       if (!prepare_log_message(index_file, prefix) && !in_merge &&
-           !allow_empty && !(amend && is_a_merge(head_sha1))) {
-               run_status(stdout, index_file, prefix, 0);
+       /* Set up everything for writing the commit object.  This includes
+          running hooks, writing the trees, and interacting with the user.  */
+       if (!prepare_to_commit(index_file, prefix)) {
                rollback_index_files();
-               unlink(commit_editmsg);
                return 1;
        }
  
-       /*
-        * Re-read the index as pre-commit hook could have updated it,
-        * and write it out as a tree.
-        */
-       discard_cache();
-       read_cache_from(index_file);
-       if (!active_cache_tree)
-               active_cache_tree = cache_tree();
-       if (cache_tree_update(active_cache_tree,
-                             active_cache, active_nr, 0, 0) < 0) {
-               rollback_index_files();
-               die("Error building trees");
-       }
- 
        /*
         * The commit object
         */
@@@ -873,19 -915,8 +921,8 @@@
                strbuf_addf(&sb, "encoding %s\n", git_commit_encoding);
        strbuf_addch(&sb, '\n');
  
-       /* Get the commit message and validate it */
+       /* Finally, get the commit message */
        header_len = sb.len;
-       if (use_editor) {
-               char index[PATH_MAX];
-               const char *env[2] = { index, NULL };
-               snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
-               launch_editor(git_path(commit_editmsg), NULL, env);
-       }
-       if (!no_verify &&
-           run_hook(index_file, "commit-msg", git_path(commit_editmsg))) {
-               rollback_index_files();
-               exit(1);
-       }
        if (strbuf_read_file(&sb, git_path(commit_editmsg), 0) < 0) {
                rollback_index_files();
                die("could not read commit message");
@@@ -935,7 -966,6 +972,7 @@@
  
        unlink(git_path("MERGE_HEAD"));
        unlink(git_path("MERGE_MSG"));
 +      unlink(git_path("SQUASH_MSG"));
  
        if (commit_index_files())
                die ("Repository has been updated, but unable to write\n"