log-tree.c

   1 #include "cache.h"
   2 #include "diff.h"
   3 #include "commit.h"
   4 #include "tag.h"
   5 #include "graph.h"
   6 #include "log-tree.h"
   7 #include "reflog-walk.h"
   8 #include "refs.h"
   9 #include "string-list.h"
  10 #include "color.h"
  11
  12 struct decoration name_decoration = { "object names" };
  13
  14 enum decoration_type {
  15         DECORATION_NONE = 0,
  16         DECORATION_REF_LOCAL,
  17         DECORATION_REF_REMOTE,
  18         DECORATION_REF_TAG,
  19         DECORATION_REF_STASH,
  20         DECORATION_REF_HEAD,
  21 };
  22
  23 static char decoration_colors[][COLOR_MAXLEN] = {
  24         GIT_COLOR_RESET,
  25         GIT_COLOR_BOLD_GREEN,   /* REF_LOCAL */
  26         GIT_COLOR_BOLD_RED,     /* REF_REMOTE */
  27         GIT_COLOR_BOLD_YELLOW,  /* REF_TAG */
  28         GIT_COLOR_BOLD_MAGENTA, /* REF_STASH */
  29         GIT_COLOR_BOLD_CYAN,    /* REF_HEAD */
  30 };
  31
  32 static const char *decorate_get_color(int decorate_use_color, enum decoration_type ix)
  33 {
  34         if (decorate_use_color)
  35                 return decoration_colors[ix];
  36         return "";
  37 }
  38
  39 static int parse_decorate_color_slot(const char *slot)
  40 {
  41         /*
  42          * We're comparing with 'ignore-case' on
  43          * (because config.c sets them all tolower),
  44          * but let's match the letters in the literal
  45          * string values here with how they are
  46          * documented in Documentation/config.txt, for
  47          * consistency.
  48          *
  49          * We love being consistent, don't we?
  50          */
  51         if (!strcasecmp(slot, "branch"))
  52                 return DECORATION_REF_LOCAL;
  53         if (!strcasecmp(slot, "remoteBranch"))
  54                 return DECORATION_REF_REMOTE;
  55         if (!strcasecmp(slot, "tag"))
  56                 return DECORATION_REF_TAG;
  57         if (!strcasecmp(slot, "stash"))
  58                 return DECORATION_REF_STASH;
  59         if (!strcasecmp(slot, "HEAD"))
  60                 return DECORATION_REF_HEAD;
  61         return -1;
  62 }
  63
  64 int parse_decorate_color_config(const char *var, const int ofs, const char *value)
  65 {
  66         int slot = parse_decorate_color_slot(var + ofs);
  67         if (slot < 0)
  68                 return 0;
  69         if (!value)
  70                 return config_error_nonbool(var);
  71         color_parse(value, var, decoration_colors[slot]);
  72         return 0;
  73 }
  74
  75 /*
  76  * log-tree.c uses DIFF_OPT_TST for determining whether to use color
  77  * for showing the commit sha1, use the same check for --decorate
  78  */
  79 #define decorate_get_color_opt(o, ix) \
  80         decorate_get_color(DIFF_OPT_TST((o), COLOR_DIFF), ix)
  81
  82 static void add_name_decoration(enum decoration_type type, const char *name, struct object *obj)
  83 {
  84         int nlen = strlen(name);
  85         struct name_decoration *res = xmalloc(sizeof(struct name_decoration) + nlen);
  86         memcpy(res->name, name, nlen + 1);
  87         res->type = type;
  88         res->next = add_decoration(&name_decoration, obj, res);
  89 }
  90
  91 static int add_ref_decoration(const char *refname, const unsigned char *sha1, int flags, void *cb_data)
  92 {
  93         struct object *obj = parse_object(sha1);
  94         enum decoration_type type = DECORATION_NONE;
  95         if (!obj)
  96                 return 0;
  97
  98         if (!prefixcmp(refname, "refs/heads"))
  99                 type = DECORATION_REF_LOCAL;
 100         else if (!prefixcmp(refname, "refs/remotes"))
 101                 type = DECORATION_REF_REMOTE;
 102         else if (!prefixcmp(refname, "refs/tags"))
 103                 type = DECORATION_REF_TAG;
 104         else if (!prefixcmp(refname, "refs/stash"))
 105                 type = DECORATION_REF_STASH;
 106         else if (!prefixcmp(refname, "HEAD"))
 107                 type = DECORATION_REF_HEAD;
 108
 109         if (!cb_data || *(int *)cb_data == DECORATE_SHORT_REFS)
 110                 refname = prettify_refname(refname);
 111         add_name_decoration(type, refname, obj);
 112         while (obj->type == OBJ_TAG) {
 113                 obj = ((struct tag *)obj)->tagged;
 114                 if (!obj)
 115                         break;
 116                 add_name_decoration(DECORATION_REF_TAG, refname, obj);
 117         }
 118         return 0;
 119 }
 120
 121 void load_ref_decorations(int flags)
 122 {
 123         static int loaded;
 124         if (!loaded) {
 125                 loaded = 1;
 126                 for_each_ref(add_ref_decoration, &flags);
 127                 head_ref(add_ref_decoration, &flags);
 128         }
 129 }
 130
 131 static void show_parents(struct commit *commit, int abbrev)
 132 {
 133         struct commit_list *p;
 134         for (p = commit->parents; p ; p = p->next) {
 135                 struct commit *parent = p->item;
 136                 printf(" %s", find_unique_abbrev(parent->object.sha1, abbrev));
 137         }
 138 }
 139
 140 void show_decorations(struct rev_info *opt, struct commit *commit)
 141 {
 142         const char *prefix;
 143         struct name_decoration *decoration;
 144         const char *color_commit =
 145                 diff_get_color_opt(&opt->diffopt, DIFF_COMMIT);
 146         const char *color_reset =
 147                 decorate_get_color_opt(&opt->diffopt, DECORATION_NONE);
 148
 149         if (opt->show_source && commit->util)
 150                 printf("\t%s", (char *) commit->util);
 151         if (!opt->show_decorations)
 152                 return;
 153         decoration = lookup_decoration(&name_decoration, &commit->object);
 154         if (!decoration)
 155                 return;
 156         prefix = " (";
 157         while (decoration) {
 158                 printf("%s", prefix);
 159                 fputs(decorate_get_color_opt(&opt->diffopt, decoration->type),
 160                       stdout);
 161                 if (decoration->type == DECORATION_REF_TAG)
 162                         fputs("tag: ", stdout);
 163                 printf("%s", decoration->name);
 164                 fputs(color_reset, stdout);
 165                 fputs(color_commit, stdout);
 166                 prefix = ", ";
 167                 decoration = decoration->next;
 168         }
 169         putchar(')');
 170 }
 171
 172 /*
 173  * Search for "^[-A-Za-z]+: [^@]+@" pattern. It usually matches
 174  * Signed-off-by: and Acked-by: lines.
 175  */
 176 static int detect_any_signoff(char *letter, int size)
 177 {
 178         char *cp;
 179         int seen_colon = 0;
 180         int seen_at = 0;
 181         int seen_name = 0;
 182         int seen_head = 0;
 183
 184         cp = letter + size;
 185         while (letter <= --cp && *cp == '\n')
 186                 continue;
 187
 188         while (letter <= cp) {
 189                 char ch = *cp--;
 190                 if (ch == '\n')
 191                         break;
 192
 193                 if (!seen_at) {
 194                         if (ch == '@')
 195                                 seen_at = 1;
 196                         continue;
 197                 }
 198                 if (!seen_colon) {
 199                         if (ch == '@')
 200                                 return 0;
 201                         else if (ch == ':')
 202                                 seen_colon = 1;
 203                         else
 204                                 seen_name = 1;
 205                         continue;
 206                 }
 207                 if (('A' <= ch && ch <= 'Z') ||
 208                     ('a' <= ch && ch <= 'z') ||
 209                     ch == '-') {
 210                         seen_head = 1;
 211                         continue;
 212                 }
 213                 /* no empty last line doesn't match */
 214                 return 0;
 215         }
 216         return seen_head && seen_name;
 217 }
 218
 219 static void append_signoff(struct strbuf *sb, const char *signoff)
 220 {
 221         static const char signed_off_by[] = "Signed-off-by: ";
 222         size_t signoff_len = strlen(signoff);
 223         int has_signoff = 0;
 224         char *cp;
 225
 226         cp = sb->buf;
 227
 228         /* First see if we already have the sign-off by the signer */
 229         while ((cp = strstr(cp, signed_off_by))) {
 230
 231                 has_signoff = 1;
 232
 233                 cp += strlen(signed_off_by);
 234                 if (cp + signoff_len >= sb->buf + sb->len)
 235                         break;
 236                 if (strncmp(cp, signoff, signoff_len))
 237                         continue;
 238                 if (!isspace(cp[signoff_len]))
 239                         continue;
 240                 /* we already have him */
 241                 return;
 242         }
 243
 244         if (!has_signoff)
 245                 has_signoff = detect_any_signoff(sb->buf, sb->len);
 246
 247         if (!has_signoff)
 248                 strbuf_addch(sb, '\n');
 249
 250         strbuf_addstr(sb, signed_off_by);
 251         strbuf_add(sb, signoff, signoff_len);
 252         strbuf_addch(sb, '\n');
 253 }
 254
 255 static unsigned int digits_in_number(unsigned int number)
 256 {
 257         unsigned int i = 10, result = 1;
 258         while (i <= number) {
 259                 i *= 10;
 260                 result++;
 261         }
 262         return result;
 263 }
 264
 265 void get_patch_filename(struct commit *commit, int nr, const char *suffix,
 266                         struct strbuf *buf)
 267 {
 268         int suffix_len = strlen(suffix) + 1;
 269         int start_len = buf->len;
 270
 271         strbuf_addf(buf, commit ? "%04d-" : "%d", nr);
 272         if (commit) {
 273                 int max_len = start_len + FORMAT_PATCH_NAME_MAX - suffix_len;
 274                 struct pretty_print_context ctx = {0};
 275                 ctx.date_mode = DATE_NORMAL;
 276
 277                 format_commit_message(commit, "%f", buf, &ctx);
 278                 if (max_len < buf->len)
 279                         strbuf_setlen(buf, max_len);
 280                 strbuf_addstr(buf, suffix);
 281         }
 282 }
 283
 284 void log_write_email_headers(struct rev_info *opt, struct commit *commit,
 285                              const char **subject_p,
 286                              const char **extra_headers_p,
 287                              int *need_8bit_cte_p)
 288 {
 289         const char *subject = NULL;
 290         const char *extra_headers = opt->extra_headers;
 291         const char *name = sha1_to_hex(commit->object.sha1);
 292
 293         *need_8bit_cte_p = 0; /* unknown */
 294         if (opt->total > 0) {
 295                 static char buffer[64];
 296                 snprintf(buffer, sizeof(buffer),
 297                          "Subject: [%s %0*d/%d] ",
 298                          opt->subject_prefix,
 299                          digits_in_number(opt->total),
 300                          opt->nr, opt->total);
 301                 subject = buffer;
 302         } else if (opt->total == 0 && opt->subject_prefix && *opt->subject_prefix) {
 303                 static char buffer[256];
 304                 snprintf(buffer, sizeof(buffer),
 305                          "Subject: [%s] ",
 306                          opt->subject_prefix);
 307                 subject = buffer;
 308         } else {
 309                 subject = "Subject: ";
 310         }
 311
 312         printf("From %s Mon Sep 17 00:00:00 2001\n", name);
 313         graph_show_oneline(opt->graph);
 314         if (opt->message_id) {
 315                 printf("Message-Id: <%s>\n", opt->message_id);
 316                 graph_show_oneline(opt->graph);
 317         }
 318         if (opt->ref_message_ids && opt->ref_message_ids->nr > 0) {
 319                 int i, n;
 320                 n = opt->ref_message_ids->nr;
 321                 printf("In-Reply-To: <%s>\n", opt->ref_message_ids->items[n-1].string);
 322                 for (i = 0; i < n; i++)
 323                         printf("%s<%s>\n", (i > 0 ? "\t" : "References: "),
 324                                opt->ref_message_ids->items[i].string);
 325                 graph_show_oneline(opt->graph);
 326         }
 327         if (opt->mime_boundary) {
 328                 static char subject_buffer[1024];
 329                 static char buffer[1024];
 330                 struct strbuf filename =  STRBUF_INIT;
 331                 *need_8bit_cte_p = -1; /* NEVER */
 332                 snprintf(subject_buffer, sizeof(subject_buffer) - 1,
 333                          "%s"
 334                          "MIME-Version: 1.0\n"
 335                          "Content-Type: multipart/mixed;"
 336                          " boundary=\"%s%s\"\n"
 337                          "\n"
 338                          "This is a multi-part message in MIME "
 339                          "format.\n"
 340                          "--%s%s\n"
 341                          "Content-Type: text/plain; "
 342                          "charset=UTF-8; format=fixed\n"
 343                          "Content-Transfer-Encoding: 8bit\n\n",
 344                          extra_headers ? extra_headers : "",
 345                          mime_boundary_leader, opt->mime_boundary,
 346                          mime_boundary_leader, opt->mime_boundary);
 347                 extra_headers = subject_buffer;
 348
 349                 get_patch_filename(opt->numbered_files ? NULL : commit, opt->nr,
 350                                     opt->patch_suffix, &filename);
 351                 snprintf(buffer, sizeof(buffer) - 1,
 352                          "\n--%s%s\n"
 353                          "Content-Type: text/x-patch;"
 354                          " name=\"%s\"\n"
 355                          "Content-Transfer-Encoding: 8bit\n"
 356                          "Content-Disposition: %s;"
 357                          " filename=\"%s\"\n\n",
 358                          mime_boundary_leader, opt->mime_boundary,
 359                          filename.buf,
 360                          opt->no_inline ? "attachment" : "inline",
 361                          filename.buf);
 362                 opt->diffopt.stat_sep = buffer;
 363                 strbuf_release(&filename);
 364         }
 365         *subject_p = subject;
 366         *extra_headers_p = extra_headers;
 367 }
 368
 369 void show_log(struct rev_info *opt)
 370 {
 371         struct strbuf msgbuf = STRBUF_INIT;
 372         struct log_info *log = opt->loginfo;
 373         struct commit *commit = log->commit, *parent = log->parent;
 374         int abbrev_commit = opt->abbrev_commit ? opt->abbrev : 40;
 375         const char *extra_headers = opt->extra_headers;
 376         struct pretty_print_context ctx = {0};
 377
 378         opt->loginfo = NULL;
 379         ctx.show_notes = opt->show_notes;
 380         if (!opt->verbose_header) {
 381                 graph_show_commit(opt->graph);
 382
 383                 if (!opt->graph) {
 384                         if (commit->object.flags & BOUNDARY)
 385                                 putchar('-');
 386                         else if (commit->object.flags & UNINTERESTING)
 387                                 putchar('^');
 388                         else if (opt->left_right) {
 389                                 if (commit->object.flags & SYMMETRIC_LEFT)
 390                                         putchar('<');
 391                                 else
 392                                         putchar('>');
 393                         }
 394                 }
 395                 fputs(find_unique_abbrev(commit->object.sha1, abbrev_commit), stdout);
 396                 if (opt->print_parents)
 397                         show_parents(commit, abbrev_commit);
 398                 show_decorations(opt, commit);
 399                 if (opt->graph && !graph_is_commit_finished(opt->graph)) {
 400                         putchar('\n');
 401                         graph_show_remainder(opt->graph);
 402                 }
 403                 putchar(opt->diffopt.line_termination);
 404                 return;
 405         }
 406
 407         /*
 408          * If use_terminator is set, we already handled any record termination
 409          * at the end of the last record.
 410          * Otherwise, add a diffopt.line_termination character before all
 411          * entries but the first.  (IOW, as a separator between entries)
 412          */
 413         if (opt->shown_one && !opt->use_terminator) {
 414                 /*
 415                  * If entries are separated by a newline, the output
 416                  * should look human-readable.  If the last entry ended
 417                  * with a newline, print the graph output before this
 418                  * newline.  Otherwise it will end up as a completely blank
 419                  * line and will look like a gap in the graph.
 420                  *
 421                  * If the entry separator is not a newline, the output is
 422                  * primarily intended for programmatic consumption, and we
 423                  * never want the extra graph output before the entry
 424                  * separator.
 425                  */
 426                 if (opt->diffopt.line_termination == '\n' &&
 427                     !opt->missing_newline)
 428                         graph_show_padding(opt->graph);
 429                 putchar(opt->diffopt.line_termination);
 430         }
 431         opt->shown_one = 1;
 432
 433         /*
 434          * If the history graph was requested,
 435          * print the graph, up to this commit's line
 436          */
 437         graph_show_commit(opt->graph);
 438
 439         /*
 440          * Print header line of header..
 441          */
 442
 443         if (opt->commit_format == CMIT_FMT_EMAIL) {
 444                 log_write_email_headers(opt, commit, &ctx.subject, &extra_headers,
 445                                         &ctx.need_8bit_cte);
 446         } else if (opt->commit_format != CMIT_FMT_USERFORMAT) {
 447                 fputs(diff_get_color_opt(&opt->diffopt, DIFF_COMMIT), stdout);
 448                 if (opt->commit_format != CMIT_FMT_ONELINE)
 449                         fputs("commit ", stdout);
 450
 451                 if (!opt->graph) {
 452                         if (commit->object.flags & BOUNDARY)
 453                                 putchar('-');
 454                         else if (commit->object.flags & UNINTERESTING)
 455                                 putchar('^');
 456                         else if (opt->left_right) {
 457                                 if (commit->object.flags & SYMMETRIC_LEFT)
 458                                         putchar('<');
 459                                 else
 460                                         putchar('>');
 461                         }
 462                 }
 463                 fputs(find_unique_abbrev(commit->object.sha1, abbrev_commit),
 464                       stdout);
 465                 if (opt->print_parents)
 466                         show_parents(commit, abbrev_commit);
 467                 if (parent)
 468                         printf(" (from %s)",
 469                                find_unique_abbrev(parent->object.sha1,
 470                                                   abbrev_commit));
 471                 show_decorations(opt, commit);
 472                 printf("%s", diff_get_color_opt(&opt->diffopt, DIFF_RESET));
 473                 if (opt->commit_format == CMIT_FMT_ONELINE) {
 474                         putchar(' ');
 475                 } else {
 476                         putchar('\n');
 477                         graph_show_oneline(opt->graph);
 478                 }
 479                 if (opt->reflog_info) {
 480                         /*
 481                          * setup_revisions() ensures that opt->reflog_info
 482                          * and opt->graph cannot both be set,
 483                          * so we don't need to worry about printing the
 484                          * graph info here.
 485                          */
 486                         show_reflog_message(opt->reflog_info,
 487                                     opt->commit_format == CMIT_FMT_ONELINE,
 488                                     opt->date_mode_explicit ?
 489                                         opt->date_mode :
 490                                         DATE_NORMAL);
 491                         if (opt->commit_format == CMIT_FMT_ONELINE)
 492                                 return;
 493                 }
 494         }
 495
 496         if (!commit->buffer)
 497                 return;
 498
 499         /*
 500          * And then the pretty-printed message itself
 501          */
 502         if (ctx.need_8bit_cte >= 0)
 503                 ctx.need_8bit_cte = has_non_ascii(opt->add_signoff);
 504         ctx.date_mode = opt->date_mode;
 505         ctx.abbrev = opt->diffopt.abbrev;
 506         ctx.after_subject = extra_headers;
 507         ctx.reflog_info = opt->reflog_info;
 508         pretty_print_commit(opt->commit_format, commit, &msgbuf, &ctx);
 509
 510         if (opt->add_signoff)
 511                 append_signoff(&msgbuf, opt->add_signoff);
 512         if (opt->show_log_size) {
 513                 printf("log size %i\n", (int)msgbuf.len);
 514                 graph_show_oneline(opt->graph);
 515         }
 516
 517         /*
 518          * Set opt->missing_newline if msgbuf doesn't
 519          * end in a newline (including if it is empty)
 520          */
 521         if (!msgbuf.len || msgbuf.buf[msgbuf.len - 1] != '\n')
 522                 opt->missing_newline = 1;
 523         else
 524                 opt->missing_newline = 0;
 525
 526         if (opt->graph)
 527                 graph_show_commit_msg(opt->graph, &msgbuf);
 528         else
 529                 /* Do not use fwrite() to give MinGW reencoding a chance */
 530                 printf("%.*s", (int)msgbuf.len, msgbuf.buf);
 531         if (opt->use_terminator) {
 532                 if (!opt->missing_newline)
 533                         graph_show_padding(opt->graph);
 534                 putchar('\n');
 535         }
 536
 537         strbuf_release(&msgbuf);
 538 }
 539
 540 int log_tree_diff_flush(struct rev_info *opt)
 541 {
 542         diffcore_std(&opt->diffopt);
 543
 544         if (diff_queue_is_empty()) {
 545                 int saved_fmt = opt->diffopt.output_format;
 546                 opt->diffopt.output_format = DIFF_FORMAT_NO_OUTPUT;
 547                 diff_flush(&opt->diffopt);
 548                 opt->diffopt.output_format = saved_fmt;
 549                 return 0;
 550         }
 551
 552         if (opt->loginfo && !opt->no_commit_id) {
 553                 /* When showing a verbose header (i.e. log message),
 554                  * and not in --pretty=oneline format, we would want
 555                  * an extra newline between the end of log and the
 556                  * output for readability.
 557                  */
 558                 show_log(opt);
 559                 if ((opt->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT) &&
 560                     opt->verbose_header &&
 561                     opt->commit_format != CMIT_FMT_ONELINE) {
 562                         int pch = DIFF_FORMAT_DIFFSTAT | DIFF_FORMAT_PATCH;
 563                         if ((pch & opt->diffopt.output_format) == pch)
 564                                 printf("---");
 565                         if (opt->diffopt.output_prefix) {
 566                                 struct strbuf *msg = NULL;
 567                                 msg = opt->diffopt.output_prefix(&opt->diffopt,
 568                                         opt->diffopt.output_prefix_data);
 569                                 fwrite(msg->buf, msg->len, 1, stdout);
 570                         }
 571                         putchar('\n');
 572                 }
 573         }
 574         diff_flush(&opt->diffopt);
 575         return 1;
 576 }
 577
 578 static int do_diff_combined(struct rev_info *opt, struct commit *commit)
 579 {
 580         unsigned const char *sha1 = commit->object.sha1;
 581
 582         diff_tree_combined_merge(sha1, opt->dense_combined_merges, opt);
 583         return !opt->loginfo;
 584 }
 585
 586 /*
 587  * Show the diff of a commit.
 588  *
 589  * Return true if we printed any log info messages
 590  */
 591 static int log_tree_diff(struct rev_info *opt, struct commit *commit, struct log_info *log)
 592 {
 593         int showed_log;
 594         struct commit_list *parents;
 595         unsigned const char *sha1 = commit->object.sha1;
 596
 597         if (!opt->diff && !DIFF_OPT_TST(&opt->diffopt, EXIT_WITH_STATUS))
 598                 return 0;
 599
 600         /* Root commit? */
 601         parents = commit->parents;
 602         if (!parents) {
 603                 if (opt->show_root_diff) {
 604                         diff_root_tree_sha1(sha1, "", &opt->diffopt);
 605                         log_tree_diff_flush(opt);
 606                 }
 607                 return !opt->loginfo;
 608         }
 609
 610         /* More than one parent? */
 611         if (parents && parents->next) {
 612                 if (opt->ignore_merges)
 613                         return 0;
 614                 else if (opt->combine_merges)
 615                         return do_diff_combined(opt, commit);
 616                 else if (opt->first_parent_only) {
 617                         /*
 618                          * Generate merge log entry only for the first
 619                          * parent, showing summary diff of the others
 620                          * we merged _in_.
 621                          */
 622                         diff_tree_sha1(parents->item->object.sha1, sha1, "", &opt->diffopt);
 623                         log_tree_diff_flush(opt);
 624                         return !opt->loginfo;
 625                 }
 626
 627                 /* If we show individual diffs, show the parent info */
 628                 log->parent = parents->item;
 629         }
 630
 631         showed_log = 0;
 632         for (;;) {
 633                 struct commit *parent = parents->item;
 634
 635                 diff_tree_sha1(parent->object.sha1, sha1, "", &opt->diffopt);
 636                 log_tree_diff_flush(opt);
 637
 638                 showed_log |= !opt->loginfo;
 639
 640                 /* Set up the log info for the next parent, if any.. */
 641                 parents = parents->next;
 642                 if (!parents)
 643                         break;
 644                 log->parent = parents->item;
 645                 opt->loginfo = log;
 646         }
 647         return showed_log;
 648 }
 649
 650 int log_tree_commit(struct rev_info *opt, struct commit *commit)
 651 {
 652         struct log_info log;
 653         int shown;
 654
 655         log.commit = commit;
 656         log.parent = NULL;
 657         opt->loginfo = &log;
 658
 659         shown = log_tree_diff(opt, commit, &log);
 660         if (!shown && opt->loginfo && opt->always_show_header) {
 661                 log.parent = NULL;
 662                 show_log(opt);
 663                 shown = 1;
 664         }
 665         opt->loginfo = NULL;
 666         maybe_flush_or_die(stdout, "stdout");
 667         return shown;
 668 }