/*
 * Builtin "git log" and related commands (show, whatchanged)
 *
 * (C) Copyright 2006 Linus Torvalds
 *               2006 Junio Hamano
 */
#include "cache.h"
#include "commit.h"
#include "diff.h"
#include "revision.h"
#include "log-tree.h"
#include "builtin.h"
#include "tag.h"
#include "reflog-walk.h"
#include "patch-ids.h"
#include "refs.h"

static int default_show_root = 1;
static const char *fmt_patch_subject_prefix = "PATCH";

static void add_name_decoration(const char *prefix, const char *name, struct object *obj)
{
        int plen = strlen(prefix);
        int nlen = strlen(name);
        struct name_decoration *res = xmalloc(sizeof(struct name_decoration) + plen + nlen);
        memcpy(res->name, prefix, plen);
        memcpy(res->name + plen, name, nlen + 1);
        res->next = add_decoration(&name_decoration, obj, res);
}

static int add_ref_decoration(const char *refname, const unsigned char *sha1, int flags, void *cb_data)
{
        struct object *obj = parse_object(sha1);
        if (!obj)
                return 0;
        add_name_decoration("", refname, obj);
        while (obj->type == OBJ_TAG) {
                obj = ((struct tag *)obj)->tagged;
                if (!obj)
                        break;
                add_name_decoration("tag: ", refname, obj);
        }
        return 0;
}

static void cmd_log_init(int argc, const char **argv, const char *prefix,
                      struct rev_info *rev)
{
        int i;
        int decorate = 0;

        rev->abbrev = DEFAULT_ABBREV;
        rev->commit_format = CMIT_FMT_DEFAULT;
        rev->verbose_header = 1;
        DIFF_OPT_SET(&rev->diffopt, RECURSIVE);
        rev->show_root_diff = default_show_root;
        rev->subject_prefix = fmt_patch_subject_prefix;
        argc = setup_revisions(argc, argv, rev, "HEAD");
        if (rev->diffopt.pickaxe || rev->diffopt.filter)
                rev->always_show_header = 0;
        if (DIFF_OPT_TST(&rev->diffopt, FOLLOW_RENAMES)) {
                rev->always_show_header = 0;
                if (rev->diffopt.nr_paths != 1)
                        usage("git logs can only follow renames on one pathname at a time");
        }
        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
                if (!strcmp(arg, "--decorate")) {
                        if (!decorate)
                                for_each_ref(add_ref_decoration, NULL);
                        decorate = 1;
                } else
                        die("unrecognized argument: %s", arg);
        }
}

/*
 * This gives a rough estimate for how many commits we
 * will print out in the list.
 */
static int estimate_commit_count(struct rev_info *rev, struct commit_list *list)
{
        int n = 0;

        while (list) {
                struct commit *commit = list->item;
                unsigned int flags = commit->object.flags;
                list = list->next;
                if (!(flags & (TREESAME | UNINTERESTING)))
                        n++;
        }
        return n;
}

static void show_early_header(struct rev_info *rev, const char *stage, int nr)
{
        if (rev->shown_one) {
                rev->shown_one = 0;
                if (rev->commit_format != CMIT_FMT_ONELINE)
                        putchar(rev->diffopt.line_termination);
        }
        printf("Final output: %d %s\n", nr, stage);
}

struct itimerval early_output_timer;

static void log_show_early(struct rev_info *revs, struct commit_list *list)
{
        int i = revs->early_output;
        int show_header = 1;

        sort_in_topological_order(&list, revs->lifo);
        while (list && i) {
                struct commit *commit = list->item;
                switch (simplify_commit(revs, commit)) {
                case commit_show:
                        if (show_header) {
                                int n = estimate_commit_count(revs, list);
                                show_early_header(revs, "incomplete", n);
                                show_header = 0;
                        }
                        log_tree_commit(revs, commit);
                        i--;
                        break;
                case commit_ignore:
                        break;
                case commit_error:
                        return;
                }
                list = list->next;
        }

        /* Did we already get enough commits for the early output? */
        if (!i)
                return;

        /*
         * ..if no, then repeat it twice a second until we
         * do.
         *
         * NOTE! We don't use "it_interval", because if the
         * reader isn't listening, we want our output to be
         * throttled by the writing, and not have the timer
         * trigger every second even if we're blocked on a
         * reader!
         */
        early_output_timer.it_value.tv_sec = 0;
        early_output_timer.it_value.tv_usec = 500000;
        setitimer(ITIMER_REAL, &early_output_timer, NULL);
}

static void early_output(int signal)
{
        show_early_output = log_show_early;
}

static void setup_early_output(struct rev_info *rev)
{
        struct sigaction sa;

        /*
         * Set up the signal handler, minimally intrusively:
         * we only set a single volatile integer word (not
         * using sigatomic_t - trying to avoid unnecessary
         * system dependencies and headers), and using
         * SA_RESTART.
         */
        memset(&sa, 0, sizeof(sa));
        sa.sa_handler = early_output;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = SA_RESTART;
        sigaction(SIGALRM, &sa, NULL);

        /*
         * If we can get the whole output in less than a
         * tenth of a second, don't even bother doing the
         * early-output thing..
         *
         * This is a one-time-only trigger.
         */
        early_output_timer.it_value.tv_sec = 0;
        early_output_timer.it_value.tv_usec = 100000;
        setitimer(ITIMER_REAL, &early_output_timer, NULL);
}

static void finish_early_output(struct rev_info *rev)
{
        int n = estimate_commit_count(rev, rev->commits);
        signal(SIGALRM, SIG_IGN);
        show_early_header(rev, "done", n);
}

static int cmd_log_walk(struct rev_info *rev)
{
        struct commit *commit;

        if (rev->early_output)
                setup_early_output(rev);

        prepare_revision_walk(rev);

        if (rev->early_output)
                finish_early_output(rev);

        while ((commit = get_revision(rev)) != NULL) {
                log_tree_commit(rev, commit);
                if (!rev->reflog_info) {
                        /* we allow cycles in reflog ancestry */
                        free(commit->buffer);
                        commit->buffer = NULL;
                }
                free_commit_list(commit->parents);
                commit->parents = NULL;
        }
        return 0;
}

static int git_log_config(const char *var, const char *value)
{
        if (!strcmp(var, "format.subjectprefix")) {
                if (!value)
                        die("format.subjectprefix without value");
                fmt_patch_subject_prefix = xstrdup(value);
                return 0;
        }
        if (!strcmp(var, "log.showroot")) {
                default_show_root = git_config_bool(var, value);
                return 0;
        }
        return git_diff_ui_config(var, value);
}

int cmd_whatchanged(int argc, const char **argv, const char *prefix)
{
        struct rev_info rev;

        git_config(git_log_config);
        init_revisions(&rev, prefix);
        rev.diff = 1;
        rev.simplify_history = 0;
        cmd_log_init(argc, argv, prefix, &rev);
        if (!rev.diffopt.output_format)
                rev.diffopt.output_format = DIFF_FORMAT_RAW;
        return cmd_log_walk(&rev);
}

static void show_tagger(char *buf, int len, struct rev_info *rev)
{
        char *email_end, *p;
        unsigned long date;
        int tz;

        email_end = memchr(buf, '>', len);
        if (!email_end)
                return;
        p = ++email_end;
        while (isspace(*p))
                p++;
        date = strtoul(p, &p, 10);
        while (isspace(*p))
                p++;
        tz = (int)strtol(p, NULL, 10);
        printf("Tagger: %.*s\nDate:   %s\n", (int)(email_end - buf), buf,
               show_date(date, tz, rev->date_mode));
}

static int show_object(const unsigned char *sha1, int show_tag_object,
        struct rev_info *rev)
{
        unsigned long size;
        enum object_type type;
        char *buf = read_sha1_file(sha1, &type, &size);
        int offset = 0;

        if (!buf)
                return error("Could not read object %s", sha1_to_hex(sha1));

        if (show_tag_object)
                while (offset < size && buf[offset] != '\n') {
                        int new_offset = offset + 1;
                        while (new_offset < size && buf[new_offset++] != '\n')
                                ; /* do nothing */
                        if (!prefixcmp(buf + offset, "tagger "))
                                show_tagger(buf + offset + 7,
                                            new_offset - offset - 7, rev);
                        offset = new_offset;
                }

        if (offset < size)
                fwrite(buf + offset, size - offset, 1, stdout);
        free(buf);
        return 0;
}

static int show_tree_object(const unsigned char *sha1,
                const char *base, int baselen,
                const char *pathname, unsigned mode, int stage)
{
        printf("%s%s\n", pathname, S_ISDIR(mode) ? "/" : "");
        return 0;
}

int cmd_show(int argc, const char **argv, const char *prefix)
{
        struct rev_info rev;
        struct object_array_entry *objects;
        int i, count, ret = 0;

        git_config(git_log_config);
        init_revisions(&rev, prefix);
        rev.diff = 1;
        rev.combine_merges = 1;
        rev.dense_combined_merges = 1;
        rev.always_show_header = 1;
        rev.ignore_merges = 0;
        rev.no_walk = 1;
        cmd_log_init(argc, argv, prefix, &rev);

        count = rev.pending.nr;
        objects = rev.pending.objects;
        for (i = 0; i < count && !ret; i++) {
                struct object *o = objects[i].item;
                const char *name = objects[i].name;
                switch (o->type) {
                case OBJ_BLOB:
                        ret = show_object(o->sha1, 0, NULL);
                        break;
                case OBJ_TAG: {
                        struct tag *t = (struct tag *)o;

                        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);
                        objects[i].item = (struct object *)t->tagged;
                        i--;
                        break;
                }
                case OBJ_TREE:
                        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);
                        break;
                case OBJ_COMMIT:
                        rev.pending.nr = rev.pending.alloc = 0;
                        rev.pending.objects = NULL;
                        add_object_array(o, name, &rev.pending);
                        ret = cmd_log_walk(&rev);
                        break;
                default:
                        ret = error("Unknown type: %d", o->type);
                }
        }
        free(objects);
        return ret;
}

/*
 * This is equivalent to "git log -g --abbrev-commit --pretty=oneline"
 */
int cmd_log_reflog(int argc, const char **argv, const char *prefix)
{
        struct rev_info rev;

        git_config(git_log_config);
        init_revisions(&rev, prefix);
        init_reflog_walk(&rev.reflog_info);
        rev.abbrev_commit = 1;
        rev.verbose_header = 1;
        cmd_log_init(argc, argv, prefix, &rev);

        /*
         * This means that we override whatever commit format the user gave
         * on the cmd line.  Sad, but cmd_log_init() currently doesn't
         * allow us to set a different default.
         */
        rev.commit_format = CMIT_FMT_ONELINE;
        rev.always_show_header = 1;

        /*
         * We get called through "git reflog", so unlike the other log
         * routines, we need to set up our pager manually..
         */
        setup_pager();

        return cmd_log_walk(&rev);
}

int cmd_log(int argc, const char **argv, const char *prefix)
{
        struct rev_info rev;

        git_config(git_log_config);
        init_revisions(&rev, prefix);
        rev.always_show_header = 1;
        cmd_log_init(argc, argv, prefix, &rev);
        return cmd_log_walk(&rev);
}

/* 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 char *extra_headers = NULL;
static int extra_headers_size = 0;
static const char *fmt_patch_suffix = ".patch";
static int numbered = 0;
static int auto_number = 0;

static int git_format_config(const char *var, const char *value)
{
        if (!strcmp(var, "format.headers")) {
                int len;

                if (!value)
                        die("format.headers without value");
                len = strlen(value);
                extra_headers_size += len + 1;
                extra_headers = xrealloc(extra_headers, extra_headers_size);
                extra_headers[extra_headers_size - len - 1] = 0;
                strcat(extra_headers, value);
                return 0;
        }
        if (!strcmp(var, "format.suffix")) {
                if (!value)
                        die("format.suffix without value");
                fmt_patch_suffix = xstrdup(value);
                return 0;
        }
        if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
                return 0;
        }
        if (!strcmp(var, "format.numbered")) {
                if (!strcasecmp(value, "auto")) {
                        auto_number = 1;
                        return 0;
                }

                numbered = git_config_bool(var, value);
                return 0;
        }

        return git_log_config(var, value);
}


static FILE *realstdout = NULL;
static const char *output_directory = NULL;

static int reopen_stdout(struct commit *commit, int nr, int keep_subject,
                         int numbered_files)
{
        char filename[PATH_MAX];
        char *sol;
        int len = 0;
        int suffix_len = strlen(fmt_patch_suffix) + 1;

        if (output_directory) {
                if (strlen(output_directory) >=
                    sizeof(filename) - FORMAT_PATCH_NAME_MAX - suffix_len)
                        return error("name of output directory is too long");
                strlcpy(filename, output_directory, sizeof(filename) - suffix_len);
                len = strlen(filename);
                if (filename[len - 1] != '/')
                        filename[len++] = '/';
        }

        if (numbered_files) {
                sprintf(filename + len, "%d", nr);
                len = strlen(filename);

        } else {
                sprintf(filename + len, "%04d", nr);
                len = strlen(filename);

                sol = strstr(commit->buffer, "\n\n");
                if (sol) {
                        int j, space = 1;

                        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;
                                }
                        }

                        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;
                        }
                        while (filename[len - 1] == '.'
                               || filename[len - 1] == '-')
                                len--;
                        filename[len] = 0;
                }
                if (len + suffix_len >= sizeof(filename))
                        return error("Patch pathname too long");
                strcpy(filename + len, fmt_patch_suffix);
        }

        fprintf(realstdout, "%s\n", filename);
        if (freopen(filename, "w", stdout) == NULL)
                return error("Cannot open patch file %s",filename);

        return 0;
}

static void get_patch_ids(struct rev_info *rev, struct patch_ids *ids, const char *prefix)
{
        struct rev_info check_rev;
        struct commit *commit;
        struct object *o1, *o2;
        unsigned flags1, flags2;

        if (rev->pending.nr != 2)
                die("Need exactly one range.");

        o1 = rev->pending.objects[0].item;
        flags1 = o1->flags;
        o2 = rev->pending.objects[1].item;
        flags2 = o2->flags;

        if ((flags1 & UNINTERESTING) == (flags2 & UNINTERESTING))
                die("Not a range.");

        init_patch_ids(ids);

        /* given a range a..b get all patch ids for b..a */
        init_revisions(&check_rev, prefix);
        o1->flags ^= UNINTERESTING;
        o2->flags ^= UNINTERESTING;
        add_pending_object(&check_rev, o1, "o1");
        add_pending_object(&check_rev, o2, "o2");
        prepare_revision_walk(&check_rev);

        while ((commit = get_revision(&check_rev)) != NULL) {
                /* ignore merges */
                if (commit->parents && commit->parents->next)
                        continue;

                add_commit_patch_id(commit, ids);
        }

        /* reset for next revision walk */
        clear_commit_marks((struct commit *)o1,
                        SEEN | UNINTERESTING | SHOWN | ADDED);
        clear_commit_marks((struct commit *)o2,
                        SEEN | UNINTERESTING | SHOWN | ADDED);
        o1->flags = flags1;
        o2->flags = flags2;
}

static void gen_message_id(char *dest, unsigned int length, char *base)
{
        const char *committer = git_committer_info(IDENT_WARN_ON_NO_NAME);
        const char *email_start = strrchr(committer, '<');
        const char *email_end = strrchr(committer, '>');
        if(!email_start || !email_end || email_start > email_end - 1)
                die("Could not extract email from committer identity.");
        snprintf(dest, length, "%s.%lu.git.%.*s", base,
                 (unsigned long) time(NULL),
                 (int)(email_end - email_start - 1), email_start + 1);
}

static const char *clean_message_id(const char *msg_id)
{
        char ch;
        const char *a, *z, *m;

        m = msg_id;
        while ((ch = *m) && (isspace(ch) || (ch == '<')))
                m++;
        a = m;
        z = NULL;
        while ((ch = *m)) {
                if (!isspace(ch) && (ch != '>'))
                        z = m;
                m++;
        }
        if (!z)
                die("insane in-reply-to: %s", msg_id);
        if (++z == m)
                return a;
        return xmemdupz(a, z - a);
}

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 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;
        const char *in_reply_to = NULL;
        struct patch_ids ids;
        char *add_signoff = NULL;
        char message_id[1024];
        char ref_message_id[1024];

        git_config(git_format_config);
        init_revisions(&rev, prefix);
        rev.commit_format = CMIT_FMT_EMAIL;
        rev.verbose_header = 1;
        rev.diff = 1;
        rev.combine_merges = 0;
        rev.ignore_merges = 1;
        rev.diffopt.msg_sep = "";
        DIFF_OPT_SET(&rev.diffopt, RECURSIVE);

        rev.subject_prefix = fmt_patch_subject_prefix;
        rev.extra_headers = extra_headers;

        /*
         * 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 (!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("bogos committer info %s\n", 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
                        argv[j++] = argv[i];
        }
        argc = j;

        if (start_number < 0)
                start_number = 1;
        if (numbered && keep_subject)
                die ("-n and -k are mutually exclusive.");
        if (keep_subject && subject_prefix)
                die ("--subject-prefix and -k are mutually exclusive.");
        if (numbered_files && use_stdout)
                die ("--numbered-files and --stdout are mutually exclusive.");

        argc = setup_revisions(argc, argv, &rev, "HEAD");
        if (argc > 1)
                die ("unrecognized argument: %s", argv[1]);

        if (!rev.diffopt.output_format)
                rev.diffopt.output_format = DIFF_FORMAT_DIFFSTAT | DIFF_FORMAT_SUMMARY | DIFF_FORMAT_PATCH;

        if (!DIFF_OPT_TST(&rev.diffopt, TEXT))
                DIFF_OPT_SET(&rev.diffopt, BINARY);

        if (!output_directory && !use_stdout)
                output_directory = prefix;

        if (output_directory) {
                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);
        }

        if (rev.pending.nr == 1) {
                if (rev.max_count < 0 && !rev.show_root_diff) {
                        /*
                         * This is traditional behaviour of "git format-patch
                         * origin" that prepares what the origin side still
                         * does not have.
                         */
                        rev.pending.objects[0].item->flags |= UNINTERESTING;
                        add_head_to_pending(&rev);
                }
                /*
                 * Otherwise, it is "format-patch -22 HEAD", and/or
                 * "format-patch --root HEAD".  The user wants
                 * get_revision() to do the usual traversal.
                 */
        }

        if (ignore_if_in_upstream)
                get_patch_ids(&rev, &ids, prefix);

        if (!use_stdout)
                realstdout = xfdopen(xdup(1), "w");

        prepare_revision_walk(&rev);
        while ((commit = get_revision(&rev)) != NULL) {
                /* ignore merges */
                if (commit->parents && commit->parents->next)
                        continue;

                if (ignore_if_in_upstream &&
                                has_commit_patch_id(commit, &ids))
                        continue;

                nr++;
                list = xrealloc(list, nr * sizeof(list[0]));
                list[nr - 1] = commit;
        }
        total = nr;
        if (!keep_subject && auto_number && total > 1)
                numbered = 1;
        if (numbered)
                rev.total = total + start_number - 1;
        rev.add_signoff = add_signoff;
        if (in_reply_to)
                rev.ref_message_id = clean_message_id(in_reply_to);
        while (0 <= --nr) {
                int shown;
                commit = list[nr];
                rev.nr = total - nr + (start_number - 1);
                /* Make the second and subsequent mails replies to the first */
                if (thread) {
                        if (nr == (total - 2)) {
                                strncpy(ref_message_id, message_id,
                                        sizeof(ref_message_id));
                                ref_message_id[sizeof(ref_message_id)-1]='\0';
                                rev.ref_message_id = ref_message_id;
                        }
                        gen_message_id(message_id, sizeof(message_id),
                                       sha1_to_hex(commit->object.sha1));
                        rev.message_id = message_id;
                }
                if (!use_stdout)
                        if (reopen_stdout(commit, rev.nr, keep_subject,
                                          numbered_files))
                                die("Failed to create output files");
                shown = log_tree_commit(&rev, commit);
                free(commit->buffer);
                commit->buffer = NULL;

                /* We put one extra blank line between formatted
                 * patches and this flag is used by log-tree code
                 * to see if it needs to emit a LF before showing
                 * the log; when using one file per patch, we do
                 * not want the extra blank line.
                 */
                if (!use_stdout)
                        rev.shown_one = 0;
                if (shown) {
                        if (rev.mime_boundary)
                                printf("\n--%s%s--\n\n\n",
                                       mime_boundary_leader,
                                       rev.mime_boundary);
                        else
                                printf("-- \n%s\n\n", git_version_string);
                }
                if (!use_stdout)
                        fclose(stdout);
        }
        free(list);
        if (ignore_if_in_upstream)
                free_patch_ids(&ids);
        return 0;
}

static int add_pending_commit(const char *arg, struct rev_info *revs, int flags)
{
        unsigned char sha1[20];
        if (get_sha1(arg, sha1) == 0) {
                struct commit *commit = lookup_commit_reference(sha1);
                if (commit) {
                        commit->object.flags |= flags;
                        add_pending_object(revs, &commit->object, arg);
                        return 0;
                }
        }
        return -1;
}

static const char cherry_usage[] =
"git-cherry [-v] <upstream> [<head>] [<limit>]";
int cmd_cherry(int argc, const char **argv, const char *prefix)
{
        struct rev_info revs;
        struct patch_ids ids;
        struct commit *commit;
        struct commit_list *list = NULL;
        const char *upstream;
        const char *head = "HEAD";
        const char *limit = NULL;
        int verbose = 0;

        if (argc > 1 && !strcmp(argv[1], "-v")) {
                verbose = 1;
                argc--;
                argv++;
        }

        switch (argc) {
        case 4:
                limit = argv[3];
                /* FALLTHROUGH */
        case 3:
                head = argv[2];
                /* FALLTHROUGH */
        case 2:
                upstream = argv[1];
                break;
        default:
                usage(cherry_usage);
        }

        init_revisions(&revs, prefix);
        revs.diff = 1;
        revs.combine_merges = 0;
        revs.ignore_merges = 1;
        DIFF_OPT_SET(&revs.diffopt, RECURSIVE);

        if (add_pending_commit(head, &revs, 0))
                die("Unknown commit %s", head);
        if (add_pending_commit(upstream, &revs, UNINTERESTING))
                die("Unknown commit %s", upstream);

        /* Don't say anything if head and upstream are the same. */
        if (revs.pending.nr == 2) {
                struct object_array_entry *o = revs.pending.objects;
                if (hashcmp(o[0].item->sha1, o[1].item->sha1) == 0)
                        return 0;
        }

        get_patch_ids(&revs, &ids, prefix);

        if (limit && add_pending_commit(limit, &revs, UNINTERESTING))
                die("Unknown commit %s", limit);

        /* reverse the list of commits */
        prepare_revision_walk(&revs);
        while ((commit = get_revision(&revs)) != NULL) {
                /* ignore merges */
                if (commit->parents && commit->parents->next)
                        continue;

                commit_list_insert(commit, &list);
        }

        while (list) {
                char sign = '+';

                commit = list->item;
                if (has_commit_patch_id(commit, &ids))
                        sign = '-';

                if (verbose) {
                        struct strbuf buf;
                        strbuf_init(&buf, 0);
                        pretty_print_commit(CMIT_FMT_ONELINE, commit,
                                            &buf, 0, NULL, NULL, 0, 0);
                        printf("%c %s %s\n", sign,
                               sha1_to_hex(commit->object.sha1), buf.buf);
                        strbuf_release(&buf);
                }
                else {
                        printf("%c %s\n", sign,
                               sha1_to_hex(commit->object.sha1));
                }

                list = list->next;
        }

        free_patch_ids(&ids);
        return 0;
}