checkout: refer to other-worktree branch, not ref

[git/gitster.git] / log-tree.c

#define USE_THE_REPOSITORY_VARIABLE

#include "git-compat-util.h"
#include "commit-reach.h"
#include "config.h"
#include "diff.h"
#include "diffcore.h"
#include "environment.h"
#include "hex.h"
#include "object-name.h"
#include "object-store-ll.h"
#include "repository.h"
#include "tmp-objdir.h"
#include "commit.h"
#include "tag.h"
#include "graph.h"
#include "log-tree.h"
#include "merge-ort.h"
#include "reflog-walk.h"
#include "refs.h"
#include "replace-object.h"
#include "revision.h"
#include "string-list.h"
#include "color.h"
#include "gpg-interface.h"
#include "sequencer.h"
#include "line-log.h"
#include "help.h"
#include "range-diff.h"
#include "strmap.h"
#include "tree.h"
#include "wildmatch.h"
#include "write-or-die.h"
#include "pager.h"

static struct decoration name_decoration = { "object names" };
static int decoration_loaded;
static int decoration_flags;

static char decoration_colors[][COLOR_MAXLEN] = {
        GIT_COLOR_RESET,
        GIT_COLOR_BOLD_GREEN,   /* REF_LOCAL */
        GIT_COLOR_BOLD_RED,     /* REF_REMOTE */
        GIT_COLOR_BOLD_YELLOW,  /* REF_TAG */
        GIT_COLOR_BOLD_MAGENTA, /* REF_STASH */
        GIT_COLOR_BOLD_CYAN,    /* REF_HEAD */
        GIT_COLOR_BOLD_BLUE,    /* GRAFTED */
};

static const char *color_decorate_slots[] = {
        [DECORATION_REF_LOCAL]  = "branch",
        [DECORATION_REF_REMOTE] = "remoteBranch",
        [DECORATION_REF_TAG]    = "tag",
        [DECORATION_REF_STASH]  = "stash",
        [DECORATION_REF_HEAD]   = "HEAD",
        [DECORATION_GRAFTED]    = "grafted",
};

static const char *decorate_get_color(int decorate_use_color, enum decoration_type ix)
{
        if (want_color(decorate_use_color))
                return decoration_colors[ix];
        return "";
}

define_list_config_array(color_decorate_slots);

int parse_decorate_color_config(const char *var, const char *slot_name, const char *value)
{
        int slot = LOOKUP_CONFIG(color_decorate_slots, slot_name);
        if (slot < 0)
                return 0;
        if (!value)
                return config_error_nonbool(var);
        return color_parse(value, decoration_colors[slot]);
}

/*
 * log-tree.c uses DIFF_OPT_TST for determining whether to use color
 * for showing the commit sha1, use the same check for --decorate
 */
#define decorate_get_color_opt(o, ix) \
        decorate_get_color((o)->use_color, ix)

void add_name_decoration(enum decoration_type type, const char *name, struct object *obj)
{
        struct name_decoration *res;
        FLEX_ALLOC_STR(res, name, name);
        res->type = type;
        res->next = add_decoration(&name_decoration, obj, res);
}

const struct name_decoration *get_name_decoration(const struct object *obj)
{
        load_ref_decorations(NULL, DECORATE_SHORT_REFS);
        return lookup_decoration(&name_decoration, obj);
}

static int match_ref_pattern(const char *refname,
                             const struct string_list_item *item)
{
        int matched = 0;
        if (!item->util) {
                if (!wildmatch(item->string, refname, 0))
                        matched = 1;
        } else {
                const char *rest;
                if (skip_prefix(refname, item->string, &rest) &&
                    (!*rest || *rest == '/'))
                        matched = 1;
        }
        return matched;
}

static int ref_filter_match(const char *refname,
                            const struct decoration_filter *filter)
{
        struct string_list_item *item;
        const struct string_list *exclude_patterns = filter->exclude_ref_pattern;
        const struct string_list *include_patterns = filter->include_ref_pattern;
        const struct string_list *exclude_patterns_config =
                                filter->exclude_ref_config_pattern;

        if (exclude_patterns && exclude_patterns->nr) {
                for_each_string_list_item(item, exclude_patterns) {
                        if (match_ref_pattern(refname, item))
                                return 0;
                }
        }

        if (include_patterns && include_patterns->nr) {
                for_each_string_list_item(item, include_patterns) {
                        if (match_ref_pattern(refname, item))
                                return 1;
                }
                return 0;
        }

        if (exclude_patterns_config && exclude_patterns_config->nr) {
                for_each_string_list_item(item, exclude_patterns_config) {
                        if (match_ref_pattern(refname, item))
                                return 0;
                }
        }

        return 1;
}

static int add_ref_decoration(const char *refname, const char *referent UNUSED, const struct object_id *oid,
                              int flags UNUSED,
                              void *cb_data)
{
        int i;
        struct object *obj;
        enum object_type objtype;
        enum decoration_type deco_type = DECORATION_NONE;
        struct decoration_filter *filter = (struct decoration_filter *)cb_data;
        const char *git_replace_ref_base = ref_namespace[NAMESPACE_REPLACE].ref;

        if (filter && !ref_filter_match(refname, filter))
                return 0;

        if (starts_with(refname, git_replace_ref_base)) {
                struct object_id original_oid;
                if (!replace_refs_enabled(the_repository))
                        return 0;
                if (get_oid_hex(refname + strlen(git_replace_ref_base),
                                &original_oid)) {
                        warning("invalid replace ref %s", refname);
                        return 0;
                }
                obj = parse_object(the_repository, &original_oid);
                if (obj)
                        add_name_decoration(DECORATION_GRAFTED, "replaced", obj);
                return 0;
        }

        objtype = oid_object_info(the_repository, oid, NULL);
        if (objtype < 0)
                return 0;
        obj = lookup_object_by_type(the_repository, oid, objtype);

        for (i = 0; i < ARRAY_SIZE(ref_namespace); i++) {
                struct ref_namespace_info *info = &ref_namespace[i];

                if (!info->decoration)
                        continue;
                if (info->exact) {
                        if (!strcmp(refname, info->ref)) {
                                deco_type = info->decoration;
                                break;
                        }
                } else if (starts_with(refname, info->ref)) {
                        deco_type = info->decoration;
                        break;
                }
        }

        add_name_decoration(deco_type, refname, obj);
        while (obj->type == OBJ_TAG) {
                if (!obj->parsed)
                        parse_object(the_repository, &obj->oid);
                obj = ((struct tag *)obj)->tagged;
                if (!obj)
                        break;
                add_name_decoration(DECORATION_REF_TAG, refname, obj);
        }
        return 0;
}

static int add_graft_decoration(const struct commit_graft *graft,
                                void *cb_data UNUSED)
{
        struct commit *commit = lookup_commit(the_repository, &graft->oid);
        if (!commit)
                return 0;
        add_name_decoration(DECORATION_GRAFTED, "grafted", &commit->object);
        return 0;
}

void load_ref_decorations(struct decoration_filter *filter, int flags)
{
        if (!decoration_loaded) {
                if (filter) {
                        struct string_list_item *item;
                        for_each_string_list_item(item, filter->exclude_ref_pattern) {
                                normalize_glob_ref(item, NULL, item->string);
                        }
                        for_each_string_list_item(item, filter->include_ref_pattern) {
                                normalize_glob_ref(item, NULL, item->string);
                        }
                        for_each_string_list_item(item, filter->exclude_ref_config_pattern) {
                                normalize_glob_ref(item, NULL, item->string);
                        }
                }
                decoration_loaded = 1;
                decoration_flags = flags;
                refs_for_each_ref(get_main_ref_store(the_repository),
                                  add_ref_decoration, filter);
                refs_head_ref(get_main_ref_store(the_repository),
                              add_ref_decoration, filter);
                for_each_commit_graft(add_graft_decoration, filter);
        }
}

static void show_parents(struct commit *commit, int abbrev, FILE *file)
{
        struct commit_list *p;
        for (p = commit->parents; p ; p = p->next) {
                struct commit *parent = p->item;
                fprintf(file, " %s",
                        repo_find_unique_abbrev(the_repository, &parent->object.oid, abbrev));
        }
}

static void show_children(struct rev_info *opt, struct commit *commit, int abbrev)
{
        struct commit_list *p = lookup_decoration(&opt->children, &commit->object);
        for ( ; p; p = p->next) {
                fprintf(opt->diffopt.file, " %s",
                        repo_find_unique_abbrev(the_repository, &p->item->object.oid, abbrev));
        }
}

/*
 * Do we have HEAD in the output, and also the branch it points at?
 * If so, find that decoration entry for that current branch.
 */
static const struct name_decoration *current_pointed_by_HEAD(const struct name_decoration *decoration)
{
        const struct name_decoration *list, *head = NULL;
        const char *branch_name = NULL;
        int rru_flags;

        /* First find HEAD */
        for (list = decoration; list; list = list->next)
                if (list->type == DECORATION_REF_HEAD) {
                        head = list;
                        break;
                }
        if (!head)
                return NULL;

        /* Now resolve and find the matching current branch */
        branch_name = refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
                                              "HEAD", 0, NULL, &rru_flags);
        if (!branch_name || !(rru_flags & REF_ISSYMREF))
                return NULL;

        if (!starts_with(branch_name, "refs/"))
                return NULL;

        /* OK, do we have that ref in the list? */
        for (list = decoration; list; list = list->next)
                if ((list->type == DECORATION_REF_LOCAL) &&
                    !strcmp(branch_name, list->name)) {
                        return list;
                }

        return NULL;
}

static void show_name(struct strbuf *sb, const struct name_decoration *decoration)
{
        if (decoration_flags == DECORATE_SHORT_REFS)
                strbuf_addstr(sb, prettify_refname(decoration->name));
        else
                strbuf_addstr(sb, decoration->name);
}

/*
 * The caller makes sure there is no funny color before calling.
 * format_decorations ensures the same after return.
 */
void format_decorations(struct strbuf *sb,
                        const struct commit *commit,
                        int use_color,
                        const struct decoration_options *opts)
{
        const struct name_decoration *decoration;
        const struct name_decoration *current_and_HEAD;
        const char *color_commit, *color_reset;

        const char *prefix = " (";
        const char *suffix = ")";
        const char *separator = ", ";
        const char *pointer = " -> ";
        const char *tag = "tag: ";

        decoration = get_name_decoration(&commit->object);
        if (!decoration)
                return;

        if (opts) {
                if (opts->prefix)
                        prefix = opts->prefix;
                if (opts->suffix)
                        suffix = opts->suffix;
                if (opts->separator)
                        separator = opts->separator;
                if (opts->pointer)
                        pointer = opts->pointer;
                if (opts->tag)
                        tag = opts->tag;
        }

        color_commit = diff_get_color(use_color, DIFF_COMMIT);
        color_reset = decorate_get_color(use_color, DECORATION_NONE);

        current_and_HEAD = current_pointed_by_HEAD(decoration);
        while (decoration) {
                /*
                 * When both current and HEAD are there, only
                 * show HEAD->current where HEAD would have
                 * appeared, skipping the entry for current.
                 */
                if (decoration != current_and_HEAD) {
                        const char *color =
                                decorate_get_color(use_color, decoration->type);

                        if (*prefix) {
                                strbuf_addstr(sb, color_commit);
                                strbuf_addstr(sb, prefix);
                                strbuf_addstr(sb, color_reset);
                        }

                        if (*tag && decoration->type == DECORATION_REF_TAG) {
                                strbuf_addstr(sb, color);
                                strbuf_addstr(sb, tag);
                                strbuf_addstr(sb, color_reset);
                        }

                        strbuf_addstr(sb, color);
                        show_name(sb, decoration);
                        strbuf_addstr(sb, color_reset);

                        if (current_and_HEAD &&
                            decoration->type == DECORATION_REF_HEAD) {
                                strbuf_addstr(sb, color_commit);
                                strbuf_addstr(sb, pointer);
                                strbuf_addstr(sb, color_reset);
                                strbuf_addstr(sb, decorate_get_color(use_color, current_and_HEAD->type));
                                show_name(sb, current_and_HEAD);
                                strbuf_addstr(sb, color_reset);
                        }

                        prefix = separator;
                }
                decoration = decoration->next;
        }
        if (*suffix) {
                strbuf_addstr(sb, color_commit);
                strbuf_addstr(sb, suffix);
                strbuf_addstr(sb, color_reset);
        }
}

void show_decorations(struct rev_info *opt, struct commit *commit)
{
        struct strbuf sb = STRBUF_INIT;

        if (opt->sources) {
                char **slot = revision_sources_peek(opt->sources, commit);

                if (slot && *slot)
                        fprintf(opt->diffopt.file, "\t%s", *slot);
        }
        if (!opt->show_decorations)
                return;
        format_decorations(&sb, commit, opt->diffopt.use_color, NULL);
        fputs(sb.buf, opt->diffopt.file);
        strbuf_release(&sb);
}

void fmt_output_subject(struct strbuf *filename,
                        const char *subject,
                        struct rev_info *info)
{
        const char *suffix = info->patch_suffix;
        int nr = info->nr;
        int start_len = filename->len;
        int max_len = start_len + info->patch_name_max - (strlen(suffix) + 1);

        if (info->reroll_count) {
                struct strbuf temp = STRBUF_INIT;

                strbuf_addf(&temp, "v%s", info->reroll_count);
                format_sanitized_subject(filename, temp.buf, temp.len);
                strbuf_addstr(filename, "-");
                strbuf_release(&temp);
        }
        strbuf_addf(filename, "%04d-%s", nr, subject);

        if (max_len < filename->len)
                strbuf_setlen(filename, max_len);
        strbuf_addstr(filename, suffix);
}

void fmt_output_commit(struct strbuf *filename,
                       struct commit *commit,
                       struct rev_info *info)
{
        struct pretty_print_context ctx = {0};
        struct strbuf subject = STRBUF_INIT;

        repo_format_commit_message(the_repository, commit, "%f", &subject,
                                   &ctx);
        fmt_output_subject(filename, subject.buf, info);
        strbuf_release(&subject);
}

void fmt_output_email_subject(struct strbuf *sb, struct rev_info *opt)
{
        if (opt->total > 0) {
                strbuf_addf(sb, "Subject: [%s%s%0*d/%d] ",
                            opt->subject_prefix,
                            *opt->subject_prefix ? " " : "",
                            decimal_width(opt->total),
                            opt->nr, opt->total);
        } else if (opt->total == 0 && opt->subject_prefix && *opt->subject_prefix) {
                strbuf_addf(sb, "Subject: [%s] ",
                            opt->subject_prefix);
        } else {
                strbuf_addstr(sb, "Subject: ");
        }
}

void log_write_email_headers(struct rev_info *opt, struct commit *commit,
                             char **extra_headers_p,
                             int *need_8bit_cte_p,
                             int maybe_multipart)
{
        struct strbuf headers = STRBUF_INIT;
        const char *name = oid_to_hex(opt->zero_commit ?
                                      null_oid() : &commit->object.oid);

        *need_8bit_cte_p = 0; /* unknown */

        if (opt->extra_headers && *opt->extra_headers)
                strbuf_addstr(&headers, opt->extra_headers);

        fprintf(opt->diffopt.file, "From %s Mon Sep 17 00:00:00 2001\n", name);
        graph_show_oneline(opt->graph);
        if (opt->message_id) {
                fprintf(opt->diffopt.file, "Message-ID: <%s>\n", opt->message_id);
                graph_show_oneline(opt->graph);
        }
        if (opt->ref_message_ids && opt->ref_message_ids->nr > 0) {
                int i, n;
                n = opt->ref_message_ids->nr;
                fprintf(opt->diffopt.file, "In-Reply-To: <%s>\n", opt->ref_message_ids->items[n-1].string);
                for (i = 0; i < n; i++)
                        fprintf(opt->diffopt.file, "%s<%s>\n", (i > 0 ? "\t" : "References: "),
                               opt->ref_message_ids->items[i].string);
                graph_show_oneline(opt->graph);
        }
        if (opt->mime_boundary && maybe_multipart) {
                static struct strbuf buffer = STRBUF_INIT;
                struct strbuf filename =  STRBUF_INIT;
                *need_8bit_cte_p = -1; /* NEVER */

                strbuf_reset(&buffer);

                strbuf_addf(&headers,
                         "MIME-Version: 1.0\n"
                         "Content-Type: multipart/mixed;"
                         " boundary=\"%s%s\"\n"
                         "\n"
                         "This is a multi-part message in MIME "
                         "format.\n"
                         "--%s%s\n"
                         "Content-Type: text/plain; "
                         "charset=UTF-8; format=fixed\n"
                         "Content-Transfer-Encoding: 8bit\n\n",
                         mime_boundary_leader, opt->mime_boundary,
                         mime_boundary_leader, opt->mime_boundary);

                if (opt->numbered_files)
                        strbuf_addf(&filename, "%d", opt->nr);
                else
                        fmt_output_commit(&filename, commit, opt);
                strbuf_addf(&buffer,
                         "\n--%s%s\n"
                         "Content-Type: text/x-patch;"
                         " name=\"%s\"\n"
                         "Content-Transfer-Encoding: 8bit\n"
                         "Content-Disposition: %s;"
                         " filename=\"%s\"\n\n",
                         mime_boundary_leader, opt->mime_boundary,
                         filename.buf,
                         opt->no_inline ? "attachment" : "inline",
                         filename.buf);
                opt->diffopt.stat_sep = buffer.buf;
                strbuf_release(&filename);
        }
        *extra_headers_p = headers.len ? strbuf_detach(&headers, NULL) : NULL;
}

static void show_sig_lines(struct rev_info *opt, int status, const char *bol)
{
        const char *color, *reset, *eol;

        color = diff_get_color_opt(&opt->diffopt,
                                   status ? DIFF_WHITESPACE : DIFF_FRAGINFO);
        reset = diff_get_color_opt(&opt->diffopt, DIFF_RESET);
        while (*bol) {
                eol = strchrnul(bol, '\n');
                fprintf(opt->diffopt.file, "%s%.*s%s%s", color, (int)(eol - bol), bol, reset,
                       *eol ? "\n" : "");
                graph_show_oneline(opt->graph);
                bol = (*eol) ? (eol + 1) : eol;
        }
}

static void show_signature(struct rev_info *opt, struct commit *commit)
{
        struct strbuf payload = STRBUF_INIT;
        struct strbuf signature = STRBUF_INIT;
        struct signature_check sigc = { 0 };
        int status;

        if (parse_signed_commit(commit, &payload, &signature, the_hash_algo) <= 0)
                goto out;

        sigc.payload_type = SIGNATURE_PAYLOAD_COMMIT;
        sigc.payload = strbuf_detach(&payload, &sigc.payload_len);
        status = check_signature(&sigc, signature.buf, signature.len);
        if (status && !sigc.output)
                show_sig_lines(opt, status, "No signature\n");
        else
                show_sig_lines(opt, status, sigc.output);
        signature_check_clear(&sigc);

 out:
        strbuf_release(&payload);
        strbuf_release(&signature);
}

static int which_parent(const struct object_id *oid, const struct commit *commit)
{
        int nth;
        const struct commit_list *parent;

        for (nth = 0, parent = commit->parents; parent; parent = parent->next) {
                if (oideq(&parent->item->object.oid, oid))
                        return nth;
                nth++;
        }
        return -1;
}

static int is_common_merge(const struct commit *commit)
{
        return (commit->parents
                && commit->parents->next
                && !commit->parents->next->next);
}

static int show_one_mergetag(struct commit *commit,
                             struct commit_extra_header *extra,
                             void *data)
{
        struct rev_info *opt = (struct rev_info *)data;
        struct object_id oid;
        struct tag *tag;
        struct strbuf verify_message;
        struct signature_check sigc = { 0 };
        int status, nth;
        struct strbuf payload = STRBUF_INIT;
        struct strbuf signature = STRBUF_INIT;

        hash_object_file(the_hash_algo, extra->value, extra->len,
                         OBJ_TAG, &oid);
        tag = lookup_tag(the_repository, &oid);
        if (!tag)
                return -1; /* error message already given */

        strbuf_init(&verify_message, 256);
        if (parse_tag_buffer(the_repository, tag, extra->value, extra->len))
                strbuf_addstr(&verify_message, "malformed mergetag\n");
        else if (is_common_merge(commit) &&
                 oideq(&tag->tagged->oid,
                       &commit->parents->next->item->object.oid))
                strbuf_addf(&verify_message,
                            "merged tag '%s'\n", tag->tag);
        else if ((nth = which_parent(&tag->tagged->oid, commit)) < 0)
                strbuf_addf(&verify_message, "tag %s names a non-parent %s\n",
                                    tag->tag, oid_to_hex(&tag->tagged->oid));
        else
                strbuf_addf(&verify_message,
                            "parent #%d, tagged '%s'\n", nth + 1, tag->tag);

        status = -1;
        if (parse_signature(extra->value, extra->len, &payload, &signature)) {
                /* could have a good signature */
                sigc.payload_type = SIGNATURE_PAYLOAD_TAG;
                sigc.payload = strbuf_detach(&payload, &sigc.payload_len);
                status = check_signature(&sigc, signature.buf, signature.len);
                if (sigc.output)
                        strbuf_addstr(&verify_message, sigc.output);
                else
                        strbuf_addstr(&verify_message, "No signature\n");
                signature_check_clear(&sigc);
                /* otherwise we couldn't verify, which is shown as bad */
        }

        show_sig_lines(opt, status, verify_message.buf);
        strbuf_release(&verify_message);
        strbuf_release(&payload);
        strbuf_release(&signature);
        return 0;
}

static int show_mergetag(struct rev_info *opt, struct commit *commit)
{
        return for_each_mergetag(show_one_mergetag, commit, opt);
}

static void next_commentary_block(struct rev_info *opt, struct strbuf *sb)
{
        const char *x = opt->shown_dashes ? "\n" : "---\n";
        if (sb)
                strbuf_addstr(sb, x);
        else
                fputs(x, opt->diffopt.file);
        opt->shown_dashes = 1;
}

static void show_diff_of_diff(struct rev_info *opt)
{
        if (!cmit_fmt_is_mail(opt->commit_format))
                return;

        if (opt->idiff_oid1) {
                struct diff_queue_struct dq;

                memcpy(&dq, &diff_queued_diff, sizeof(diff_queued_diff));
                DIFF_QUEUE_CLEAR(&diff_queued_diff);

                fprintf_ln(opt->diffopt.file, "\n%s", opt->idiff_title);
                show_interdiff(opt->idiff_oid1, opt->idiff_oid2, 2,
                               &opt->diffopt);

                memcpy(&diff_queued_diff, &dq, sizeof(diff_queued_diff));
        }

        if (opt->rdiff1) {
                struct diff_queue_struct dq;
                struct diff_options opts;
                struct range_diff_options range_diff_opts = {
                        .creation_factor = opt->creation_factor,
                        .dual_color = 1,
                        .diffopt = &opts
                };

                memcpy(&dq, &diff_queued_diff, sizeof(diff_queued_diff));
                DIFF_QUEUE_CLEAR(&diff_queued_diff);

                fprintf_ln(opt->diffopt.file, "\n%s", opt->rdiff_title);
                /*
                 * Pass minimum required diff-options to range-diff; others
                 * can be added later if deemed desirable.
                 */
                repo_diff_setup(the_repository, &opts);
                opts.file = opt->diffopt.file;
                opts.use_color = opt->diffopt.use_color;
                diff_setup_done(&opts);
                show_range_diff(opt->rdiff1, opt->rdiff2, &range_diff_opts);

                memcpy(&diff_queued_diff, &dq, sizeof(diff_queued_diff));
        }
}

void show_log(struct rev_info *opt)
{
        struct strbuf msgbuf = STRBUF_INIT;
        struct log_info *log = opt->loginfo;
        struct commit *commit = log->commit, *parent = log->parent;
        int abbrev_commit = opt->abbrev_commit ? opt->abbrev : the_hash_algo->hexsz;
        struct pretty_print_context ctx = {0};

        opt->loginfo = NULL;
        if (!opt->verbose_header) {
                graph_show_commit(opt->graph);

                if (!opt->graph)
                        put_revision_mark(opt, commit);
                fputs(repo_find_unique_abbrev(the_repository, &commit->object.oid, abbrev_commit),
                      opt->diffopt.file);
                if (opt->print_parents)
                        show_parents(commit, abbrev_commit, opt->diffopt.file);
                if (opt->children.name)
                        show_children(opt, commit, abbrev_commit);
                show_decorations(opt, commit);
                if (opt->graph && !graph_is_commit_finished(opt->graph)) {
                        putc('\n', opt->diffopt.file);
                        graph_show_remainder(opt->graph);
                }
                putc(opt->diffopt.line_termination, opt->diffopt.file);
                return;
        }

        /*
         * If use_terminator is set, we already handled any record termination
         * at the end of the last record.
         * Otherwise, add a diffopt.line_termination character before all
         * entries but the first.  (IOW, as a separator between entries)
         */
        if (opt->shown_one && !opt->use_terminator) {
                /*
                 * If entries are separated by a newline, the output
                 * should look human-readable.  If the last entry ended
                 * with a newline, print the graph output before this
                 * newline.  Otherwise it will end up as a completely blank
                 * line and will look like a gap in the graph.
                 *
                 * If the entry separator is not a newline, the output is
                 * primarily intended for programmatic consumption, and we
                 * never want the extra graph output before the entry
                 * separator.
                 */
                if (opt->diffopt.line_termination == '\n' &&
                    !opt->missing_newline)
                        graph_show_padding(opt->graph);
                putc(opt->diffopt.line_termination, opt->diffopt.file);
        }
        opt->shown_one = 1;

        /*
         * If the history graph was requested,
         * print the graph, up to this commit's line
         */
        graph_show_commit(opt->graph);

        /*
         * Print header line of header..
         */

        if (cmit_fmt_is_mail(opt->commit_format)) {
                log_write_email_headers(opt, commit, &ctx.after_subject,
                                        &ctx.need_8bit_cte, 1);
                ctx.rev = opt;
        } else if (opt->commit_format != CMIT_FMT_USERFORMAT) {
                fputs(diff_get_color_opt(&opt->diffopt, DIFF_COMMIT), opt->diffopt.file);
                if (opt->commit_format != CMIT_FMT_ONELINE)
                        fputs("commit ", opt->diffopt.file);

                if (!opt->graph)
                        put_revision_mark(opt, commit);
                fputs(repo_find_unique_abbrev(the_repository, &commit->object.oid,
                                              abbrev_commit),
                      opt->diffopt.file);
                if (opt->print_parents)
                        show_parents(commit, abbrev_commit, opt->diffopt.file);
                if (opt->children.name)
                        show_children(opt, commit, abbrev_commit);
                if (parent)
                        fprintf(opt->diffopt.file, " (from %s)",
                               repo_find_unique_abbrev(the_repository, &parent->object.oid, abbrev_commit));
                fputs(diff_get_color_opt(&opt->diffopt, DIFF_RESET), opt->diffopt.file);
                show_decorations(opt, commit);
                if (opt->commit_format == CMIT_FMT_ONELINE) {
                        putc(' ', opt->diffopt.file);
                } else {
                        putc('\n', opt->diffopt.file);
                        graph_show_oneline(opt->graph);
                }
                if (opt->reflog_info) {
                        /*
                         * setup_revisions() ensures that opt->reflog_info
                         * and opt->graph cannot both be set,
                         * so we don't need to worry about printing the
                         * graph info here.
                         */
                        show_reflog_message(opt->reflog_info,
                                            opt->commit_format == CMIT_FMT_ONELINE,
                                            opt->date_mode,
                                            opt->date_mode_explicit);
                        if (opt->commit_format == CMIT_FMT_ONELINE)
                                return;
                }
        }

        if (opt->show_signature) {
                show_signature(opt, commit);
                show_mergetag(opt, commit);
        }

        if (opt->show_notes) {
                int raw;
                struct strbuf notebuf = STRBUF_INIT;

                raw = (opt->commit_format == CMIT_FMT_USERFORMAT);
                format_display_notes(&commit->object.oid, &notebuf,
                                     get_log_output_encoding(), raw);
                ctx.notes_message = strbuf_detach(&notebuf, NULL);
        }

        /*
         * And then the pretty-printed message itself
         */
        if (ctx.need_8bit_cte >= 0 && opt->add_signoff)
                ctx.need_8bit_cte =
                        has_non_ascii(fmt_name(WANT_COMMITTER_IDENT));
        ctx.date_mode = opt->date_mode;
        ctx.date_mode_explicit = opt->date_mode_explicit;
        ctx.abbrev = opt->diffopt.abbrev;
        ctx.preserve_subject = opt->preserve_subject;
        ctx.encode_email_headers = opt->encode_email_headers;
        ctx.reflog_info = opt->reflog_info;
        ctx.fmt = opt->commit_format;
        ctx.mailmap = opt->mailmap;
        ctx.color = opt->diffopt.use_color;
        ctx.expand_tabs_in_log = opt->expand_tabs_in_log;
        ctx.output_encoding = get_log_output_encoding();
        ctx.rev = opt;
        if (opt->from_ident.mail_begin && opt->from_ident.name_begin)
                ctx.from_ident = &opt->from_ident;
        if (opt->graph)
                ctx.graph_width = graph_width(opt->graph);
        pretty_print_commit(&ctx, commit, &msgbuf);

        if (opt->add_signoff)
                append_signoff(&msgbuf, 0, APPEND_SIGNOFF_DEDUP);

        if ((ctx.fmt != CMIT_FMT_USERFORMAT) &&
            ctx.notes_message && *ctx.notes_message) {
                if (cmit_fmt_is_mail(ctx.fmt))
                        next_commentary_block(opt, &msgbuf);
                strbuf_addstr(&msgbuf, ctx.notes_message);
        }

        if (opt->show_log_size) {
                fprintf(opt->diffopt.file, "log size %i\n", (int)msgbuf.len);
                graph_show_oneline(opt->graph);
        }

        /*
         * Set opt->missing_newline if msgbuf doesn't
         * end in a newline (including if it is empty)
         */
        if (!msgbuf.len || msgbuf.buf[msgbuf.len - 1] != '\n')
                opt->missing_newline = 1;
        else
                opt->missing_newline = 0;

        graph_show_commit_msg(opt->graph, opt->diffopt.file, &msgbuf);
        if (opt->use_terminator && !commit_format_is_empty(opt->commit_format)) {
                if (!opt->missing_newline)
                        graph_show_padding(opt->graph);
                putc(opt->diffopt.line_termination, opt->diffopt.file);
        }

        strbuf_release(&msgbuf);
        free(ctx.notes_message);
        free(ctx.after_subject);
}

int log_tree_diff_flush(struct rev_info *opt)
{
        opt->shown_dashes = 0;
        diffcore_std(&opt->diffopt);

        if (diff_queue_is_empty(&opt->diffopt)) {
                int saved_fmt = opt->diffopt.output_format;
                opt->diffopt.output_format = DIFF_FORMAT_NO_OUTPUT;
                diff_flush(&opt->diffopt);
                opt->diffopt.output_format = saved_fmt;
                return 0;
        }

        if (opt->loginfo && !opt->no_commit_id) {
                show_log(opt);
                if ((opt->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT) &&
                    opt->verbose_header &&
                    opt->commit_format != CMIT_FMT_ONELINE &&
                    !commit_format_is_empty(opt->commit_format)) {
                        /*
                         * When showing a verbose header (i.e. log message),
                         * and not in --pretty=oneline format, we would want
                         * an extra newline between the end of log and the
                         * diff/diffstat output for readability.
                         */
                        int pch = DIFF_FORMAT_DIFFSTAT | DIFF_FORMAT_PATCH;
                        if (opt->diffopt.output_prefix) {
                                struct strbuf *msg = NULL;
                                msg = opt->diffopt.output_prefix(&opt->diffopt,
                                        opt->diffopt.output_prefix_data);
                                fwrite(msg->buf, msg->len, 1, opt->diffopt.file);
                        }

                        /*
                         * We may have shown three-dashes line early
                         * between generated commentary (notes, etc.)
                         * and the log message, in which case we only
                         * want a blank line after the commentary
                         * without (an extra) three-dashes line.
                         * Otherwise, we show the three-dashes line if
                         * we are showing the patch with diffstat, but
                         * in that case, there is no extra blank line
                         * after the three-dashes line.
                         */
                        if (!opt->shown_dashes &&
                            (pch & opt->diffopt.output_format) == pch)
                                fprintf(opt->diffopt.file, "---");
                        putc('\n', opt->diffopt.file);
                }
        }
        diff_flush(&opt->diffopt);
        return 1;
}

static int do_diff_combined(struct rev_info *opt, struct commit *commit)
{
        diff_tree_combined_merge(commit, opt);
        return !opt->loginfo;
}

static void setup_additional_headers(struct diff_options *o,
                                     struct strmap *all_headers)
{
        struct hashmap_iter iter;
        struct strmap_entry *entry;

        /*
         * Make o->additional_path_headers contain the subset of all_headers
         * that match o->pathspec.  If there aren't any that match o->pathspec,
         * then make o->additional_path_headers be NULL.
         */

        if (!o->pathspec.nr) {
                o->additional_path_headers = all_headers;
                return;
        }

        o->additional_path_headers = xmalloc(sizeof(struct strmap));
        strmap_init_with_options(o->additional_path_headers, NULL, 0);
        strmap_for_each_entry(all_headers, &iter, entry) {
                if (match_pathspec(the_repository->index, &o->pathspec,
                                   entry->key, strlen(entry->key),
                                   0 /* prefix */, NULL /* seen */,
                                   0 /* is_dir */))
                        strmap_put(o->additional_path_headers,
                                   entry->key, entry->value);
        }
        if (!strmap_get_size(o->additional_path_headers)) {
                strmap_clear(o->additional_path_headers, 0);
                FREE_AND_NULL(o->additional_path_headers);
        }
}

static void cleanup_additional_headers(struct diff_options *o)
{
        if (!o->pathspec.nr) {
                o->additional_path_headers = NULL;
                return;
        }
        if (!o->additional_path_headers)
                return;

        strmap_clear(o->additional_path_headers, 0);
        FREE_AND_NULL(o->additional_path_headers);
}

static int do_remerge_diff(struct rev_info *opt,
                           struct commit_list *parents,
                           struct object_id *oid)
{
        struct merge_options o;
        struct commit_list *bases = NULL;
        struct merge_result res = {0};
        struct pretty_print_context ctx = {0};
        struct commit *parent1 = parents->item;
        struct commit *parent2 = parents->next->item;
        struct strbuf parent1_desc = STRBUF_INIT;
        struct strbuf parent2_desc = STRBUF_INIT;

        /*
         * Lazily prepare a temporary object directory and rotate it
         * into the alternative object store list as the primary.
         */
        if (opt->remerge_diff && !opt->remerge_objdir) {
                opt->remerge_objdir = tmp_objdir_create("remerge-diff");
                if (!opt->remerge_objdir)
                        return error(_("unable to create temporary object directory"));
                tmp_objdir_replace_primary_odb(opt->remerge_objdir, 1);
        }

        /* Setup merge options */
        init_ui_merge_options(&o, the_repository);
        o.show_rename_progress = 0;
        o.record_conflict_msgs_as_headers = 1;
        o.msg_header_prefix = "remerge";

        ctx.abbrev = DEFAULT_ABBREV;
        repo_format_commit_message(the_repository, parent1, "%h (%s)",
                                   &parent1_desc, &ctx);
        repo_format_commit_message(the_repository, parent2, "%h (%s)",
                                   &parent2_desc, &ctx);
        o.branch1 = parent1_desc.buf;
        o.branch2 = parent2_desc.buf;

        /* Parse the relevant commits and get the merge bases */
        parse_commit_or_die(parent1);
        parse_commit_or_die(parent2);
        if (repo_get_merge_bases(the_repository, parent1, parent2, &bases) < 0)
                exit(128);

        /* Re-merge the parents */
        merge_incore_recursive(&o, bases, parent1, parent2, &res);

        /* Show the diff */
        setup_additional_headers(&opt->diffopt, res.path_messages);
        diff_tree_oid(&res.tree->object.oid, oid, "", &opt->diffopt);
        log_tree_diff_flush(opt);

        /* Cleanup */
        free_commit_list(bases);
        cleanup_additional_headers(&opt->diffopt);
        strbuf_release(&parent1_desc);
        strbuf_release(&parent2_desc);
        merge_finalize(&o, &res);

        /* Clean up the contents of the temporary object directory */
        tmp_objdir_discard_objects(opt->remerge_objdir);

        return !opt->loginfo;
}

/*
 * Show the diff of a commit.
 *
 * Return true if we printed any log info messages
 */
static int log_tree_diff(struct rev_info *opt, struct commit *commit, struct log_info *log)
{
        int showed_log;
        struct commit_list *parents;
        struct object_id *oid;
        int is_merge;
        int all_need_diff = opt->diff || opt->diffopt.flags.exit_with_status;

        if (!all_need_diff && !opt->merges_need_diff)
                return 0;

        parse_commit_or_die(commit);
        oid = get_commit_tree_oid(commit);

        parents = get_saved_parents(opt, commit);
        is_merge = parents && parents->next;
        if (!is_merge && !all_need_diff)
                return 0;

        /* Root commit? */
        if (!parents) {
                if (opt->show_root_diff) {
                        diff_root_tree_oid(oid, "", &opt->diffopt);
                        log_tree_diff_flush(opt);
                }
                return !opt->loginfo;
        }

        if (is_merge) {
                int octopus = (parents->next->next != NULL);

                if (opt->remerge_diff) {
                        if (octopus) {
                                show_log(opt);
                                fprintf(opt->diffopt.file,
                                        "diff: warning: Skipping remerge-diff "
                                        "for octopus merges.\n");
                                return 1;
                        }
                        return do_remerge_diff(opt, parents, oid);
                }
                if (opt->combine_merges)
                        return do_diff_combined(opt, commit);
                if (opt->separate_merges) {
                        if (!opt->first_parent_merges) {
                                /* Show parent info for multiple diffs */
                                log->parent = parents->item;
                        }
                } else
                        return 0;
        }

        showed_log = 0;
        for (;;) {
                struct commit *parent = parents->item;

                parse_commit_or_die(parent);
                diff_tree_oid(get_commit_tree_oid(parent),
                              oid, "", &opt->diffopt);
                log_tree_diff_flush(opt);

                showed_log |= !opt->loginfo;

                /* Set up the log info for the next parent, if any.. */
                parents = parents->next;
                if (!parents || opt->first_parent_merges)
                        break;
                log->parent = parents->item;
                opt->loginfo = log;
        }
        return showed_log;
}

int log_tree_commit(struct rev_info *opt, struct commit *commit)
{
        struct log_info log;
        int shown;
        /* maybe called by e.g. cmd_log_walk(), maybe stand-alone */
        int no_free = opt->diffopt.no_free;

        log.commit = commit;
        log.parent = NULL;
        opt->loginfo = &log;
        opt->diffopt.no_free = 1;

        /* NEEDSWORK: no restoring of no_free?  Why? */
        if (opt->line_level_traverse)
                return line_log_print(opt, commit);

        if (opt->track_linear && !opt->linear && !opt->reverse_output_stage)
                fprintf(opt->diffopt.file, "\n%s\n", opt->break_bar);
        shown = log_tree_diff(opt, commit, &log);
        if (!shown && opt->loginfo && opt->always_show_header) {
                log.parent = NULL;
                show_log(opt);
                shown = 1;
        }
        if (opt->track_linear && !opt->linear && opt->reverse_output_stage)
                fprintf(opt->diffopt.file, "\n%s\n", opt->break_bar);
        if (shown)
                show_diff_of_diff(opt);
        opt->loginfo = NULL;
        maybe_flush_or_die(opt->diffopt.file, "stdout");
        opt->diffopt.no_free = no_free;

        diff_free(&opt->diffopt);
        return shown;
}