Allow fetch to modify refs
[gitweb.git] / builtin-log.c
index 0f0adf2bab69328f5b6320c1baca58ad226570df..25e21ed41534c8c3067c2e0d5afe4284faa2881a 100644 (file)
@@ -17,6 +17,8 @@
 #include "run-command.h"
 #include "shortlog.h"
 #include "remote.h"
+#include "string-list.h"
+#include "parse-options.h"
 
 /* Set a default date-time format for git log ("log.date" config variable) */
 static const char *default_date_mode = NULL;
@@ -25,10 +27,15 @@ static int default_show_root = 1;
 static const char *fmt_patch_subject_prefix = "PATCH";
 static const char *fmt_pretty;
 
+static const char * const builtin_log_usage =
+       "git log [<options>] [<since>..<until>] [[--] <path>...]\n"
+       "   or: git show [options] <object>...";
+
 static void cmd_log_init(int argc, const char **argv, const char *prefix,
                      struct rev_info *rev)
 {
        int i;
+       int decoration_style = 0;
 
        rev->abbrev = DEFAULT_ABBREV;
        rev->commit_format = CMIT_FMT_DEFAULT;
@@ -55,13 +62,26 @@ static void cmd_log_init(int argc, const char **argv, const char *prefix,
        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
                if (!strcmp(arg, "--decorate")) {
-                       load_ref_decorations();
-                       rev->show_decorations = 1;
+                       decoration_style = DECORATE_SHORT_REFS;
+               } else if (!prefixcmp(arg, "--decorate=")) {
+                       const char *v = skip_prefix(arg, "--decorate=");
+                       if (!strcmp(v, "full"))
+                               decoration_style = DECORATE_FULL_REFS;
+                       else if (!strcmp(v, "short"))
+                               decoration_style = DECORATE_SHORT_REFS;
+                       else
+                               die("invalid --decorate option: %s", arg);
                } else if (!strcmp(arg, "--source")) {
                        rev->show_source = 1;
+               } else if (!strcmp(arg, "-h")) {
+                       usage(builtin_log_usage);
                } else
                        die("unrecognized argument: %s", arg);
        }
+       if (decoration_style) {
+               rev->show_decorations = 1;
+               load_ref_decorations(decoration_style);
+       }
 }
 
 /*
@@ -92,7 +112,7 @@ static void show_early_header(struct rev_info *rev, const char *stage, int nr)
        printf("Final output: %d %s\n", nr, stage);
 }
 
-struct itimerval early_output_timer;
+static struct itimerval early_output_timer;
 
 static void log_show_early(struct rev_info *revs, struct commit_list *list)
 {
@@ -255,7 +275,7 @@ static void show_tagger(char *buf, int len, struct rev_info *rev)
        pp_user_info("Tagger", rev->commit_format, &out, buf, rev->date_mode,
                git_log_output_encoding ?
                git_log_output_encoding: git_commit_encoding);
-       printf("%s\n", out.buf);
+       printf("%s", out.buf);
        strbuf_release(&out);
 }
 
@@ -327,11 +347,14 @@ int cmd_show(int argc, const char **argv, const char *prefix)
                case OBJ_TAG: {
                        struct tag *t = (struct tag *)o;
 
+                       if (rev.shown_one)
+                               putchar('\n');
                        printf("%stag %s%s\n",
                                        diff_get_color_opt(&rev.diffopt, DIFF_COMMIT),
                                        t->tag,
                                        diff_get_color_opt(&rev.diffopt, DIFF_RESET));
                        ret = show_object(o->sha1, 1, &rev);
+                       rev.shown_one = 1;
                        if (ret)
                                break;
                        o = parse_object(t->tagged->sha1);
@@ -343,12 +366,15 @@ int cmd_show(int argc, const char **argv, const char *prefix)
                        break;
                }
                case OBJ_TREE:
+                       if (rev.shown_one)
+                               putchar('\n');
                        printf("%stree %s%s\n\n",
                                        diff_get_color_opt(&rev.diffopt, DIFF_COMMIT),
                                        name,
                                        diff_get_color_opt(&rev.diffopt, DIFF_RESET));
                        read_tree_recursive((struct tree *)o, "", 0, 0, NULL,
                                        show_tree_object, NULL);
+                       rev.shown_one = 1;
                        break;
                case OBJ_COMMIT:
                        rev.pending.nr = rev.pending.alloc = 0;
@@ -416,18 +442,13 @@ int cmd_log(int argc, const char **argv, const char *prefix)
 }
 
 /* format-patch */
-#define FORMAT_PATCH_NAME_MAX 64
-
-static int istitlechar(char c)
-{
-       return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
-               (c >= '0' && c <= '9') || c == '.' || c == '_';
-}
 
 static const char *fmt_patch_suffix = ".patch";
 static int numbered = 0;
 static int auto_number = 1;
 
+static char *default_attach = NULL;
+
 static char **extra_hdr;
 static int extra_hdr_nr;
 static int extra_hdr_alloc;
@@ -459,6 +480,11 @@ static void add_header(const char *value)
        extra_hdr[extra_hdr_nr++] = xstrndup(value, len);
 }
 
+#define THREAD_SHALLOW 1
+#define THREAD_DEEP 2
+static int thread = 0;
+static int do_signoff = 0;
+
 static int git_format_config(const char *var, const char *value, void *cb)
 {
        if (!strcmp(var, "format.headers")) {
@@ -488,94 +514,60 @@ static int git_format_config(const char *var, const char *value, void *cb)
                auto_number = auto_number && numbered;
                return 0;
        }
-
-       return git_log_config(var, value, cb);
-}
-
-
-static const char *get_oneline_for_filename(struct commit *commit,
-                                           int keep_subject)
-{
-       static char filename[PATH_MAX];
-       char *sol;
-       int len = 0;
-       int suffix_len = strlen(fmt_patch_suffix) + 1;
-
-       sol = strstr(commit->buffer, "\n\n");
-       if (!sol)
-               filename[0] = '\0';
-       else {
-               int j, space = 0;
-
-               sol += 2;
-               /* strip [PATCH] or [PATCH blabla] */
-               if (!keep_subject && !prefixcmp(sol, "[PATCH")) {
-                       char *eos = strchr(sol + 6, ']');
-                       if (eos) {
-                               while (isspace(*eos))
-                                       eos++;
-                               sol = eos;
-                       }
+       if (!strcmp(var, "format.attach")) {
+               if (value && *value)
+                       default_attach = xstrdup(value);
+               else
+                       default_attach = xstrdup(git_version_string);
+               return 0;
+       }
+       if (!strcmp(var, "format.thread")) {
+               if (value && !strcasecmp(value, "deep")) {
+                       thread = THREAD_DEEP;
+                       return 0;
                }
-
-               for (j = 0;
-                    j < FORMAT_PATCH_NAME_MAX - suffix_len - 5 &&
-                            len < sizeof(filename) - suffix_len &&
-                            sol[j] && sol[j] != '\n';
-                    j++) {
-                       if (istitlechar(sol[j])) {
-                               if (space) {
-                                       filename[len++] = '-';
-                                       space = 0;
-                               }
-                               filename[len++] = sol[j];
-                               if (sol[j] == '.')
-                                       while (sol[j + 1] == '.')
-                                               j++;
-                       } else
-                               space = 1;
+               if (value && !strcasecmp(value, "shallow")) {
+                       thread = THREAD_SHALLOW;
+                       return 0;
                }
-               while (filename[len - 1] == '.'
-                      || filename[len - 1] == '-')
-                       len--;
-               filename[len] = '\0';
+               thread = git_config_bool(var, value) && THREAD_SHALLOW;
+               return 0;
+       }
+       if (!strcmp(var, "format.signoff")) {
+               do_signoff = git_config_bool(var, value);
+               return 0;
        }
-       return filename;
+
+       return git_log_config(var, value, cb);
 }
 
 static FILE *realstdout = NULL;
 static const char *output_directory = NULL;
 static int outdir_offset;
 
-static int reopen_stdout(const char *oneline, int nr, int total)
+static int reopen_stdout(struct commit *commit, struct rev_info *rev)
 {
-       char filename[PATH_MAX];
-       int len = 0;
+       struct strbuf filename = STRBUF_INIT;
        int suffix_len = strlen(fmt_patch_suffix) + 1;
 
        if (output_directory) {
-               len = snprintf(filename, sizeof(filename), "%s",
-                               output_directory);
-               if (len >=
-                   sizeof(filename) - FORMAT_PATCH_NAME_MAX - suffix_len)
+               strbuf_addstr(&filename, output_directory);
+               if (filename.len >=
+                   PATH_MAX - FORMAT_PATCH_NAME_MAX - suffix_len)
                        return error("name of output directory is too long");
-               if (filename[len - 1] != '/')
-                       filename[len++] = '/';
+               if (filename.buf[filename.len - 1] != '/')
+                       strbuf_addch(&filename, '/');
        }
 
-       if (!oneline)
-               len += sprintf(filename + len, "%d", nr);
-       else {
-               len += sprintf(filename + len, "%04d-", nr);
-               len += snprintf(filename + len, sizeof(filename) - len - 1
-                               - suffix_len, "%s", oneline);
-               strcpy(filename + len, fmt_patch_suffix);
-       }
+       get_patch_filename(commit, rev->nr, fmt_patch_suffix, &filename);
+
+       if (!DIFF_OPT_TST(&rev->diffopt, QUIET))
+               fprintf(realstdout, "%s\n", filename.buf + outdir_offset);
 
-       fprintf(realstdout, "%s\n", filename + outdir_offset);
-       if (freopen(filename, "w", stdout) == NULL)
-               return error("Cannot open patch file %s",filename);
+       if (freopen(filename.buf, "w", stdout) == NULL)
+               return error("Cannot open patch file %s", filename.buf);
 
+       strbuf_release(&filename);
        return 0;
 }
 
@@ -645,7 +637,6 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
                              int nr, struct commit **list, struct commit *head)
 {
        const char *committer;
-       char *head_sha1;
        const char *subject_start = NULL;
        const char *body = "*** SUBJECT HERE ***\n\n*** BLURB HERE ***\n";
        const char *msg;
@@ -653,23 +644,47 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
        struct shortlog log;
        struct strbuf sb = STRBUF_INIT;
        int i;
-       const char *encoding = "utf-8";
+       const char *encoding = "UTF-8";
        struct diff_options opts;
        int need_8bit_cte = 0;
+       struct commit *commit = NULL;
 
        if (rev->commit_format != CMIT_FMT_EMAIL)
                die("Cover letter needs email format");
 
-       if (!use_stdout && reopen_stdout(numbered_files ?
-                               NULL : "cover-letter", 0, rev->total))
+       committer = git_committer_info(0);
+
+       if (!numbered_files) {
+               /*
+                * We fake a commit for the cover letter so we get the filename
+                * desired.
+                */
+               commit = xcalloc(1, sizeof(*commit));
+               commit->buffer = xmalloc(400);
+               snprintf(commit->buffer, 400,
+                       "tree 0000000000000000000000000000000000000000\n"
+                       "parent %s\n"
+                       "author %s\n"
+                       "committer %s\n\n"
+                       "cover letter\n",
+                       sha1_to_hex(head->object.sha1), committer, committer);
+       }
+
+       if (!use_stdout && reopen_stdout(commit, rev))
                return;
 
-       head_sha1 = sha1_to_hex(head->object.sha1);
+       if (commit) {
+
+               free(commit->buffer);
+               free(commit);
+       }
 
-       log_write_email_headers(rev, head_sha1, &subject_start, &extra_headers,
+       log_write_email_headers(rev, head, &subject_start, &extra_headers,
                                &need_8bit_cte);
 
-       committer = git_committer_info(0);
+       for (i = 0; !need_8bit_cte && i < nr; i++)
+               if (has_non_ascii(list[i]->buffer))
+                       need_8bit_cte = 1;
 
        msg = body;
        pp_user_info(NULL, CMIT_FMT_EMAIL, &sb, committer, DATE_RFC2822,
@@ -754,19 +769,120 @@ static const char *set_outdir(const char *prefix, const char *output_directory)
                                       output_directory));
 }
 
+static const char * const builtin_format_patch_usage[] = {
+       "git format-patch [options] [<since> | <revision range>]",
+       NULL
+};
+
+static int keep_subject = 0;
+
+static int keep_callback(const struct option *opt, const char *arg, int unset)
+{
+       ((struct rev_info *)opt->value)->total = -1;
+       keep_subject = 1;
+       return 0;
+}
+
+static int subject_prefix = 0;
+
+static int subject_prefix_callback(const struct option *opt, const char *arg,
+                           int unset)
+{
+       subject_prefix = 1;
+       ((struct rev_info *)opt->value)->subject_prefix = arg;
+       return 0;
+}
+
+static int numbered_cmdline_opt = 0;
+
+static int numbered_callback(const struct option *opt, const char *arg,
+                            int unset)
+{
+       *(int *)opt->value = numbered_cmdline_opt = unset ? 0 : 1;
+       if (unset)
+               auto_number =  0;
+       return 0;
+}
+
+static int no_numbered_callback(const struct option *opt, const char *arg,
+                               int unset)
+{
+       return numbered_callback(opt, arg, 1);
+}
+
+static int output_directory_callback(const struct option *opt, const char *arg,
+                             int unset)
+{
+       const char **dir = (const char **)opt->value;
+       if (*dir)
+               die("Two output directories?");
+       *dir = arg;
+       return 0;
+}
+
+static int thread_callback(const struct option *opt, const char *arg, int unset)
+{
+       int *thread = (int *)opt->value;
+       if (unset)
+               *thread = 0;
+       else if (!arg || !strcmp(arg, "shallow"))
+               *thread = THREAD_SHALLOW;
+       else if (!strcmp(arg, "deep"))
+               *thread = THREAD_DEEP;
+       else
+               return 1;
+       return 0;
+}
+
+static int attach_callback(const struct option *opt, const char *arg, int unset)
+{
+       struct rev_info *rev = (struct rev_info *)opt->value;
+       if (unset)
+               rev->mime_boundary = NULL;
+       else if (arg)
+               rev->mime_boundary = arg;
+       else
+               rev->mime_boundary = git_version_string;
+       rev->no_inline = unset ? 0 : 1;
+       return 0;
+}
+
+static int inline_callback(const struct option *opt, const char *arg, int unset)
+{
+       struct rev_info *rev = (struct rev_info *)opt->value;
+       if (unset)
+               rev->mime_boundary = NULL;
+       else if (arg)
+               rev->mime_boundary = arg;
+       else
+               rev->mime_boundary = git_version_string;
+       rev->no_inline = 0;
+       return 0;
+}
+
+static int header_callback(const struct option *opt, const char *arg, int unset)
+{
+       add_header(arg);
+       return 0;
+}
+
+static int cc_callback(const struct option *opt, const char *arg, int unset)
+{
+       ALLOC_GROW(extra_cc, extra_cc_nr + 1, extra_cc_alloc);
+       extra_cc[extra_cc_nr++] = xstrdup(arg);
+       return 0;
+}
+
 int cmd_format_patch(int argc, const char **argv, const char *prefix)
 {
        struct commit *commit;
        struct commit **list = NULL;
        struct rev_info rev;
-       int nr = 0, total, i, j;
+       int nr = 0, total, i;
        int use_stdout = 0;
        int start_number = -1;
-       int keep_subject = 0;
        int numbered_files = 0;         /* _just_ numbers */
-       int subject_prefix = 0;
        int ignore_if_in_upstream = 0;
-       int thread = 0;
        int cover_letter = 0;
        int boundary_count = 0;
        int no_binary_diff = 0;
@@ -775,6 +891,57 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
        struct patch_ids ids;
        char *add_signoff = NULL;
        struct strbuf buf = STRBUF_INIT;
+       const struct option builtin_format_patch_options[] = {
+               { OPTION_CALLBACK, 'n', "numbered", &numbered, NULL,
+                           "use [PATCH n/m] even with a single patch",
+                           PARSE_OPT_NOARG, numbered_callback },
+               { OPTION_CALLBACK, 'N', "no-numbered", &numbered, NULL,
+                           "use [PATCH] even with multiple patches",
+                           PARSE_OPT_NOARG, no_numbered_callback },
+               OPT_BOOLEAN('s', "signoff", &do_signoff, "add Signed-off-by:"),
+               OPT_BOOLEAN(0, "stdout", &use_stdout,
+                           "print patches to standard out"),
+               OPT_BOOLEAN(0, "cover-letter", &cover_letter,
+                           "generate a cover letter"),
+               OPT_BOOLEAN(0, "numbered-files", &numbered_files,
+                           "use simple number sequence for output file names"),
+               OPT_STRING(0, "suffix", &fmt_patch_suffix, "sfx",
+                           "use <sfx> instead of '.patch'"),
+               OPT_INTEGER(0, "start-number", &start_number,
+                           "start numbering patches at <n> instead of 1"),
+               { OPTION_CALLBACK, 0, "subject-prefix", &rev, "prefix",
+                           "Use [<prefix>] instead of [PATCH]",
+                           PARSE_OPT_NONEG, subject_prefix_callback },
+               { OPTION_CALLBACK, 'o', "output-directory", &output_directory,
+                           "dir", "store resulting files in <dir>",
+                           PARSE_OPT_NONEG, output_directory_callback },
+               { OPTION_CALLBACK, 'k', "keep-subject", &rev, NULL,
+                           "don't strip/add [PATCH]",
+                           PARSE_OPT_NOARG | PARSE_OPT_NONEG, keep_callback },
+               OPT_BOOLEAN(0, "no-binary", &no_binary_diff,
+                           "don't output binary diffs"),
+               OPT_BOOLEAN(0, "ignore-if-in-upstream", &ignore_if_in_upstream,
+                           "don't include a patch matching a commit upstream"),
+               OPT_GROUP("Messaging"),
+               { OPTION_CALLBACK, 0, "add-header", NULL, "header",
+                           "add email header", PARSE_OPT_NONEG,
+                           header_callback },
+               { OPTION_CALLBACK, 0, "cc", NULL, "email", "add Cc: header",
+                           PARSE_OPT_NONEG, cc_callback },
+               OPT_STRING(0, "in-reply-to", &in_reply_to, "message-id",
+                           "make first mail a reply to <message-id>"),
+               { OPTION_CALLBACK, 0, "attach", &rev, "boundary",
+                           "attach the patch", PARSE_OPT_OPTARG,
+                           attach_callback },
+               { OPTION_CALLBACK, 0, "inline", &rev, "boundary",
+                           "inline the patch",
+                           PARSE_OPT_OPTARG | PARSE_OPT_NONEG,
+                           inline_callback },
+               { OPTION_CALLBACK, 0, "thread", &thread, "style",
+                           "enable message threading, styles: shallow, deep",
+                           PARSE_OPT_OPTARG, thread_callback },
+               OPT_END()
+       };
 
        git_config(git_format_config, NULL);
        init_revisions(&rev, prefix);
@@ -787,100 +954,29 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 
        rev.subject_prefix = fmt_patch_subject_prefix;
 
+       if (default_attach) {
+               rev.mime_boundary = default_attach;
+               rev.no_inline = 1;
+       }
+
        /*
         * Parse the arguments before setup_revisions(), or something
         * like "git format-patch -o a123 HEAD^.." may fail; a123 is
         * possibly a valid SHA1.
         */
-       for (i = 1, j = 1; i < argc; i++) {
-               if (!strcmp(argv[i], "--stdout"))
-                       use_stdout = 1;
-               else if (!strcmp(argv[i], "-n") ||
-                               !strcmp(argv[i], "--numbered"))
-                       numbered = 1;
-               else if (!strcmp(argv[i], "-N") ||
-                               !strcmp(argv[i], "--no-numbered")) {
-                       numbered = 0;
-                       auto_number = 0;
-               }
-               else if (!prefixcmp(argv[i], "--start-number="))
-                       start_number = strtol(argv[i] + 15, NULL, 10);
-               else if (!strcmp(argv[i], "--numbered-files"))
-                       numbered_files = 1;
-               else if (!strcmp(argv[i], "--start-number")) {
-                       i++;
-                       if (i == argc)
-                               die("Need a number for --start-number");
-                       start_number = strtol(argv[i], NULL, 10);
-               }
-               else if (!prefixcmp(argv[i], "--cc=")) {
-                       ALLOC_GROW(extra_cc, extra_cc_nr + 1, extra_cc_alloc);
-                       extra_cc[extra_cc_nr++] = xstrdup(argv[i] + 5);
-               }
-               else if (!strcmp(argv[i], "-k") ||
-                               !strcmp(argv[i], "--keep-subject")) {
-                       keep_subject = 1;
-                       rev.total = -1;
-               }
-               else if (!strcmp(argv[i], "--output-directory") ||
-                        !strcmp(argv[i], "-o")) {
-                       i++;
-                       if (argc <= i)
-                               die("Which directory?");
-                       if (output_directory)
-                               die("Two output directories?");
-                       output_directory = argv[i];
-               }
-               else if (!strcmp(argv[i], "--signoff") ||
-                        !strcmp(argv[i], "-s")) {
-                       const char *committer;
-                       const char *endpos;
-                       committer = git_committer_info(IDENT_ERROR_ON_NO_NAME);
-                       endpos = strchr(committer, '>');
-                       if (!endpos)
-                               die("bogus committer info %s", committer);
-                       add_signoff = xmemdupz(committer, endpos - committer + 1);
-               }
-               else if (!strcmp(argv[i], "--attach")) {
-                       rev.mime_boundary = git_version_string;
-                       rev.no_inline = 1;
-               }
-               else if (!prefixcmp(argv[i], "--attach=")) {
-                       rev.mime_boundary = argv[i] + 9;
-                       rev.no_inline = 1;
-               }
-               else if (!strcmp(argv[i], "--inline")) {
-                       rev.mime_boundary = git_version_string;
-                       rev.no_inline = 0;
-               }
-               else if (!prefixcmp(argv[i], "--inline=")) {
-                       rev.mime_boundary = argv[i] + 9;
-                       rev.no_inline = 0;
-               }
-               else if (!strcmp(argv[i], "--ignore-if-in-upstream"))
-                       ignore_if_in_upstream = 1;
-               else if (!strcmp(argv[i], "--thread"))
-                       thread = 1;
-               else if (!prefixcmp(argv[i], "--in-reply-to="))
-                       in_reply_to = argv[i] + 14;
-               else if (!strcmp(argv[i], "--in-reply-to")) {
-                       i++;
-                       if (i == argc)
-                               die("Need a Message-Id for --in-reply-to");
-                       in_reply_to = argv[i];
-               } else if (!prefixcmp(argv[i], "--subject-prefix=")) {
-                       subject_prefix = 1;
-                       rev.subject_prefix = argv[i] + 17;
-               } else if (!prefixcmp(argv[i], "--suffix="))
-                       fmt_patch_suffix = argv[i] + 9;
-               else if (!strcmp(argv[i], "--cover-letter"))
-                       cover_letter = 1;
-               else if (!strcmp(argv[i], "--no-binary"))
-                       no_binary_diff = 1;
-               else
-                       argv[j++] = argv[i];
+       argc = parse_options(argc, argv, prefix, builtin_format_patch_options,
+                            builtin_format_patch_usage,
+                            PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN);
+
+       if (do_signoff) {
+               const char *committer;
+               const char *endpos;
+               committer = git_committer_info(IDENT_ERROR_ON_NO_NAME);
+               endpos = strchr(committer, '>');
+               if (!endpos)
+                       die("bogus committer info %s", committer);
+               add_signoff = xmemdupz(committer, endpos - committer + 1);
        }
-       argc = j;
 
        for (i = 0; i < extra_hdr_nr; i++) {
                strbuf_addstr(&buf, extra_hdr[i]);
@@ -909,10 +1005,19 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
                strbuf_addch(&buf, '\n');
        }
 
-       rev.extra_headers = strbuf_detach(&buf, 0);
+       rev.extra_headers = strbuf_detach(&buf, NULL);
 
        if (start_number < 0)
                start_number = 1;
+
+       /*
+        * If numbered is set solely due to format.numbered in config,
+        * and it would conflict with --keep-subject (-k) from the
+        * command line, reset "numbered".
+        */
+       if (numbered && keep_subject && !numbered_cmdline_opt)
+               numbered = 0;
+
        if (numbered && keep_subject)
                die ("-n and -k are mutually exclusive.");
        if (keep_subject && subject_prefix)
@@ -936,8 +1041,8 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
                if (use_stdout)
                        die("standard output, or directory, which one?");
                if (mkdir(output_directory, 0777) < 0 && errno != EEXIST)
-                       die("Could not create directory %s",
-                           output_directory);
+                       die_errno("Could not create directory '%s'",
+                                 output_directory);
        }
 
        if (rev.pending.nr == 1) {
@@ -1009,8 +1114,14 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
                numbered = 1;
        if (numbered)
                rev.total = total + start_number - 1;
-       if (in_reply_to)
-               rev.ref_message_id = clean_message_id(in_reply_to);
+       if (in_reply_to || thread || cover_letter)
+               rev.ref_message_ids = xcalloc(1, sizeof(struct string_list));
+       if (in_reply_to) {
+               const char *msgid = clean_message_id(in_reply_to);
+               string_list_append(msgid, rev.ref_message_ids);
+       }
+       rev.numbered_files = numbered_files;
+       rev.patch_suffix = fmt_patch_suffix;
        if (cover_letter) {
                if (thread)
                        gen_message_id(&rev, "cover");
@@ -1029,21 +1140,39 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
                        /* Have we already had a message ID? */
                        if (rev.message_id) {
                                /*
-                                * If we've got the ID to be a reply
-                                * to, discard the current ID;
-                                * otherwise, make everything a reply
-                                * to that.
+                                * For deep threading: make every mail
+                                * a reply to the previous one, no
+                                * matter what other options are set.
+                                *
+                                * For shallow threading:
+                                *
+                                * Without --cover-letter and
+                                * --in-reply-to, make every mail a
+                                * reply to the one before.
+                                *
+                                * With --in-reply-to but no
+                                * --cover-letter, make every mail a
+                                * reply to the <reply-to>.
+                                *
+                                * With --cover-letter, make every
+                                * mail but the cover letter a reply
+                                * to the cover letter.  The cover
+                                * letter is a reply to the
+                                * --in-reply-to, if specified.
                                 */
-                               if (rev.ref_message_id)
+                               if (thread == THREAD_SHALLOW
+                                   && rev.ref_message_ids->nr > 0
+                                   && (!cover_letter || rev.nr > 1))
                                        free(rev.message_id);
                                else
-                                       rev.ref_message_id = rev.message_id;
+                                       string_list_append(rev.message_id,
+                                                          rev.ref_message_ids);
                        }
                        gen_message_id(&rev, sha1_to_hex(commit->object.sha1));
                }
-               if (!use_stdout && reopen_stdout(numbered_files ? NULL :
-                               get_oneline_for_filename(commit, keep_subject),
-                               rev.nr, rev.total))
+
+               if (!use_stdout && reopen_stdout(numbered_files ? NULL : commit,
+                                                &rev))
                        die("Failed to create output files");
                shown = log_tree_commit(&rev, commit);
                free(commit->buffer);