convert.con commit Merge branch 'nd/commit-hook-doc-fix' (fbcfbc4)
   1#include "cache.h"
   2#include "attr.h"
   3#include "run-command.h"
   4#include "quote.h"
   5#include "sigchain.h"
   6#include "pkt-line.h"
   7
   8/*
   9 * convert.c - convert a file when checking it out and checking it in.
  10 *
  11 * This should use the pathname to decide on whether it wants to do some
  12 * more interesting conversions (automatic gzip/unzip, general format
  13 * conversions etc etc), but by default it just does automatic CRLF<->LF
  14 * translation when the "text" attribute or "auto_crlf" option is set.
  15 */
  16
  17/* Stat bits: When BIN is set, the txt bits are unset */
  18#define CONVERT_STAT_BITS_TXT_LF    0x1
  19#define CONVERT_STAT_BITS_TXT_CRLF  0x2
  20#define CONVERT_STAT_BITS_BIN       0x4
  21
  22enum crlf_action {
  23        CRLF_UNDEFINED,
  24        CRLF_BINARY,
  25        CRLF_TEXT,
  26        CRLF_TEXT_INPUT,
  27        CRLF_TEXT_CRLF,
  28        CRLF_AUTO,
  29        CRLF_AUTO_INPUT,
  30        CRLF_AUTO_CRLF
  31};
  32
  33struct text_stat {
  34        /* NUL, CR, LF and CRLF counts */
  35        unsigned nul, lonecr, lonelf, crlf;
  36
  37        /* These are just approximations! */
  38        unsigned printable, nonprintable;
  39};
  40
  41static void gather_stats(const char *buf, unsigned long size, struct text_stat *stats)
  42{
  43        unsigned long i;
  44
  45        memset(stats, 0, sizeof(*stats));
  46
  47        for (i = 0; i < size; i++) {
  48                unsigned char c = buf[i];
  49                if (c == '\r') {
  50                        if (i+1 < size && buf[i+1] == '\n') {
  51                                stats->crlf++;
  52                                i++;
  53                        } else
  54                                stats->lonecr++;
  55                        continue;
  56                }
  57                if (c == '\n') {
  58                        stats->lonelf++;
  59                        continue;
  60                }
  61                if (c == 127)
  62                        /* DEL */
  63                        stats->nonprintable++;
  64                else if (c < 32) {
  65                        switch (c) {
  66                                /* BS, HT, ESC and FF */
  67                        case '\b': case '\t': case '\033': case '\014':
  68                                stats->printable++;
  69                                break;
  70                        case 0:
  71                                stats->nul++;
  72                                /* fall through */
  73                        default:
  74                                stats->nonprintable++;
  75                        }
  76                }
  77                else
  78                        stats->printable++;
  79        }
  80
  81        /* If file ends with EOF then don't count this EOF as non-printable. */
  82        if (size >= 1 && buf[size-1] == '\032')
  83                stats->nonprintable--;
  84}
  85
  86/*
  87 * The same heuristics as diff.c::mmfile_is_binary()
  88 * We treat files with bare CR as binary
  89 */
  90static int convert_is_binary(unsigned long size, const struct text_stat *stats)
  91{
  92        if (stats->lonecr)
  93                return 1;
  94        if (stats->nul)
  95                return 1;
  96        if ((stats->printable >> 7) < stats->nonprintable)
  97                return 1;
  98        return 0;
  99}
 100
 101static unsigned int gather_convert_stats(const char *data, unsigned long size)
 102{
 103        struct text_stat stats;
 104        int ret = 0;
 105        if (!data || !size)
 106                return 0;
 107        gather_stats(data, size, &stats);
 108        if (convert_is_binary(size, &stats))
 109                ret |= CONVERT_STAT_BITS_BIN;
 110        if (stats.crlf)
 111                ret |= CONVERT_STAT_BITS_TXT_CRLF;
 112        if (stats.lonelf)
 113                ret |=  CONVERT_STAT_BITS_TXT_LF;
 114
 115        return ret;
 116}
 117
 118static const char *gather_convert_stats_ascii(const char *data, unsigned long size)
 119{
 120        unsigned int convert_stats = gather_convert_stats(data, size);
 121
 122        if (convert_stats & CONVERT_STAT_BITS_BIN)
 123                return "-text";
 124        switch (convert_stats) {
 125        case CONVERT_STAT_BITS_TXT_LF:
 126                return "lf";
 127        case CONVERT_STAT_BITS_TXT_CRLF:
 128                return "crlf";
 129        case CONVERT_STAT_BITS_TXT_LF | CONVERT_STAT_BITS_TXT_CRLF:
 130                return "mixed";
 131        default:
 132                return "none";
 133        }
 134}
 135
 136const char *get_cached_convert_stats_ascii(const char *path)
 137{
 138        const char *ret;
 139        unsigned long sz;
 140        void *data = read_blob_data_from_cache(path, &sz);
 141        ret = gather_convert_stats_ascii(data, sz);
 142        free(data);
 143        return ret;
 144}
 145
 146const char *get_wt_convert_stats_ascii(const char *path)
 147{
 148        const char *ret = "";
 149        struct strbuf sb = STRBUF_INIT;
 150        if (strbuf_read_file(&sb, path, 0) >= 0)
 151                ret = gather_convert_stats_ascii(sb.buf, sb.len);
 152        strbuf_release(&sb);
 153        return ret;
 154}
 155
 156static int text_eol_is_crlf(void)
 157{
 158        if (auto_crlf == AUTO_CRLF_TRUE)
 159                return 1;
 160        else if (auto_crlf == AUTO_CRLF_INPUT)
 161                return 0;
 162        if (core_eol == EOL_CRLF)
 163                return 1;
 164        if (core_eol == EOL_UNSET && EOL_NATIVE == EOL_CRLF)
 165                return 1;
 166        return 0;
 167}
 168
 169static enum eol output_eol(enum crlf_action crlf_action)
 170{
 171        switch (crlf_action) {
 172        case CRLF_BINARY:
 173                return EOL_UNSET;
 174        case CRLF_TEXT_CRLF:
 175                return EOL_CRLF;
 176        case CRLF_TEXT_INPUT:
 177                return EOL_LF;
 178        case CRLF_UNDEFINED:
 179        case CRLF_AUTO_CRLF:
 180                return EOL_CRLF;
 181        case CRLF_AUTO_INPUT:
 182                return EOL_LF;
 183        case CRLF_TEXT:
 184        case CRLF_AUTO:
 185                /* fall through */
 186                return text_eol_is_crlf() ? EOL_CRLF : EOL_LF;
 187        }
 188        warning("Illegal crlf_action %d\n", (int)crlf_action);
 189        return core_eol;
 190}
 191
 192static void check_safe_crlf(const char *path, enum crlf_action crlf_action,
 193                            struct text_stat *old_stats, struct text_stat *new_stats,
 194                            enum safe_crlf checksafe)
 195{
 196        if (old_stats->crlf && !new_stats->crlf ) {
 197                /*
 198                 * CRLFs would not be restored by checkout
 199                 */
 200                if (checksafe == SAFE_CRLF_WARN)
 201                        warning(_("CRLF will be replaced by LF in %s.\n"
 202                                  "The file will have its original line"
 203                                  " endings in your working directory."), path);
 204                else /* i.e. SAFE_CRLF_FAIL */
 205                        die(_("CRLF would be replaced by LF in %s."), path);
 206        } else if (old_stats->lonelf && !new_stats->lonelf ) {
 207                /*
 208                 * CRLFs would be added by checkout
 209                 */
 210                if (checksafe == SAFE_CRLF_WARN)
 211                        warning(_("LF will be replaced by CRLF in %s.\n"
 212                                  "The file will have its original line"
 213                                  " endings in your working directory."), path);
 214                else /* i.e. SAFE_CRLF_FAIL */
 215                        die(_("LF would be replaced by CRLF in %s"), path);
 216        }
 217}
 218
 219static int has_cr_in_index(const char *path)
 220{
 221        unsigned long sz;
 222        void *data;
 223        int has_cr;
 224
 225        data = read_blob_data_from_cache(path, &sz);
 226        if (!data)
 227                return 0;
 228        has_cr = memchr(data, '\r', sz) != NULL;
 229        free(data);
 230        return has_cr;
 231}
 232
 233static int will_convert_lf_to_crlf(size_t len, struct text_stat *stats,
 234                                   enum crlf_action crlf_action)
 235{
 236        if (output_eol(crlf_action) != EOL_CRLF)
 237                return 0;
 238        /* No "naked" LF? Nothing to convert, regardless. */
 239        if (!stats->lonelf)
 240                return 0;
 241
 242        if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 243                /* If we have any CR or CRLF line endings, we do not touch it */
 244                /* This is the new safer autocrlf-handling */
 245                if (stats->lonecr || stats->crlf)
 246                        return 0;
 247
 248                if (convert_is_binary(len, stats))
 249                        return 0;
 250        }
 251        return 1;
 252
 253}
 254
 255static int crlf_to_git(const char *path, const char *src, size_t len,
 256                       struct strbuf *buf,
 257                       enum crlf_action crlf_action, enum safe_crlf checksafe)
 258{
 259        struct text_stat stats;
 260        char *dst;
 261        int convert_crlf_into_lf;
 262
 263        if (crlf_action == CRLF_BINARY ||
 264            (src && !len))
 265                return 0;
 266
 267        /*
 268         * If we are doing a dry-run and have no source buffer, there is
 269         * nothing to analyze; we must assume we would convert.
 270         */
 271        if (!buf && !src)
 272                return 1;
 273
 274        gather_stats(src, len, &stats);
 275        /* Optimization: No CRLF? Nothing to convert, regardless. */
 276        convert_crlf_into_lf = !!stats.crlf;
 277
 278        if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 279                if (convert_is_binary(len, &stats))
 280                        return 0;
 281                /*
 282                 * If the file in the index has any CR in it, do not
 283                 * convert.  This is the new safer autocrlf handling,
 284                 * unless we want to renormalize in a merge or
 285                 * cherry-pick.
 286                 */
 287                if ((checksafe != SAFE_CRLF_RENORMALIZE) && has_cr_in_index(path))
 288                        convert_crlf_into_lf = 0;
 289        }
 290        if ((checksafe == SAFE_CRLF_WARN ||
 291            (checksafe == SAFE_CRLF_FAIL)) && len) {
 292                struct text_stat new_stats;
 293                memcpy(&new_stats, &stats, sizeof(new_stats));
 294                /* simulate "git add" */
 295                if (convert_crlf_into_lf) {
 296                        new_stats.lonelf += new_stats.crlf;
 297                        new_stats.crlf = 0;
 298                }
 299                /* simulate "git checkout" */
 300                if (will_convert_lf_to_crlf(len, &new_stats, crlf_action)) {
 301                        new_stats.crlf += new_stats.lonelf;
 302                        new_stats.lonelf = 0;
 303                }
 304                check_safe_crlf(path, crlf_action, &stats, &new_stats, checksafe);
 305        }
 306        if (!convert_crlf_into_lf)
 307                return 0;
 308
 309        /*
 310         * At this point all of our source analysis is done, and we are sure we
 311         * would convert. If we are in dry-run mode, we can give an answer.
 312         */
 313        if (!buf)
 314                return 1;
 315
 316        /* only grow if not in place */
 317        if (strbuf_avail(buf) + buf->len < len)
 318                strbuf_grow(buf, len - buf->len);
 319        dst = buf->buf;
 320        if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 321                /*
 322                 * If we guessed, we already know we rejected a file with
 323                 * lone CR, and we can strip a CR without looking at what
 324                 * follow it.
 325                 */
 326                do {
 327                        unsigned char c = *src++;
 328                        if (c != '\r')
 329                                *dst++ = c;
 330                } while (--len);
 331        } else {
 332                do {
 333                        unsigned char c = *src++;
 334                        if (! (c == '\r' && (1 < len && *src == '\n')))
 335                                *dst++ = c;
 336                } while (--len);
 337        }
 338        strbuf_setlen(buf, dst - buf->buf);
 339        return 1;
 340}
 341
 342static int crlf_to_worktree(const char *path, const char *src, size_t len,
 343                            struct strbuf *buf, enum crlf_action crlf_action)
 344{
 345        char *to_free = NULL;
 346        struct text_stat stats;
 347
 348        if (!len || output_eol(crlf_action) != EOL_CRLF)
 349                return 0;
 350
 351        gather_stats(src, len, &stats);
 352        if (!will_convert_lf_to_crlf(len, &stats, crlf_action))
 353                return 0;
 354
 355        /* are we "faking" in place editing ? */
 356        if (src == buf->buf)
 357                to_free = strbuf_detach(buf, NULL);
 358
 359        strbuf_grow(buf, len + stats.lonelf);
 360        for (;;) {
 361                const char *nl = memchr(src, '\n', len);
 362                if (!nl)
 363                        break;
 364                if (nl > src && nl[-1] == '\r') {
 365                        strbuf_add(buf, src, nl + 1 - src);
 366                } else {
 367                        strbuf_add(buf, src, nl - src);
 368                        strbuf_addstr(buf, "\r\n");
 369                }
 370                len -= nl + 1 - src;
 371                src  = nl + 1;
 372        }
 373        strbuf_add(buf, src, len);
 374
 375        free(to_free);
 376        return 1;
 377}
 378
 379struct filter_params {
 380        const char *src;
 381        unsigned long size;
 382        int fd;
 383        const char *cmd;
 384        const char *path;
 385};
 386
 387static int filter_buffer_or_fd(int in, int out, void *data)
 388{
 389        /*
 390         * Spawn cmd and feed the buffer contents through its stdin.
 391         */
 392        struct child_process child_process = CHILD_PROCESS_INIT;
 393        struct filter_params *params = (struct filter_params *)data;
 394        int write_err, status;
 395        const char *argv[] = { NULL, NULL };
 396
 397        /* apply % substitution to cmd */
 398        struct strbuf cmd = STRBUF_INIT;
 399        struct strbuf path = STRBUF_INIT;
 400        struct strbuf_expand_dict_entry dict[] = {
 401                { "f", NULL, },
 402                { NULL, NULL, },
 403        };
 404
 405        /* quote the path to preserve spaces, etc. */
 406        sq_quote_buf(&path, params->path);
 407        dict[0].value = path.buf;
 408
 409        /* expand all %f with the quoted path */
 410        strbuf_expand(&cmd, params->cmd, strbuf_expand_dict_cb, &dict);
 411        strbuf_release(&path);
 412
 413        argv[0] = cmd.buf;
 414
 415        child_process.argv = argv;
 416        child_process.use_shell = 1;
 417        child_process.in = -1;
 418        child_process.out = out;
 419
 420        if (start_command(&child_process))
 421                return error("cannot fork to run external filter '%s'", params->cmd);
 422
 423        sigchain_push(SIGPIPE, SIG_IGN);
 424
 425        if (params->src) {
 426                write_err = (write_in_full(child_process.in,
 427                                           params->src, params->size) < 0);
 428                if (errno == EPIPE)
 429                        write_err = 0;
 430        } else {
 431                write_err = copy_fd(params->fd, child_process.in);
 432                if (write_err == COPY_WRITE_ERROR && errno == EPIPE)
 433                        write_err = 0;
 434        }
 435
 436        if (close(child_process.in))
 437                write_err = 1;
 438        if (write_err)
 439                error("cannot feed the input to external filter '%s'", params->cmd);
 440
 441        sigchain_pop(SIGPIPE);
 442
 443        status = finish_command(&child_process);
 444        if (status)
 445                error("external filter '%s' failed %d", params->cmd, status);
 446
 447        strbuf_release(&cmd);
 448        return (write_err || status);
 449}
 450
 451static int apply_single_file_filter(const char *path, const char *src, size_t len, int fd,
 452                        struct strbuf *dst, const char *cmd)
 453{
 454        /*
 455         * Create a pipeline to have the command filter the buffer's
 456         * contents.
 457         *
 458         * (child --> cmd) --> us
 459         */
 460        int err = 0;
 461        struct strbuf nbuf = STRBUF_INIT;
 462        struct async async;
 463        struct filter_params params;
 464
 465        memset(&async, 0, sizeof(async));
 466        async.proc = filter_buffer_or_fd;
 467        async.data = &params;
 468        async.out = -1;
 469        params.src = src;
 470        params.size = len;
 471        params.fd = fd;
 472        params.cmd = cmd;
 473        params.path = path;
 474
 475        fflush(NULL);
 476        if (start_async(&async))
 477                return 0;       /* error was already reported */
 478
 479        if (strbuf_read(&nbuf, async.out, len) < 0) {
 480                err = error("read from external filter '%s' failed", cmd);
 481        }
 482        if (close(async.out)) {
 483                err = error("read from external filter '%s' failed", cmd);
 484        }
 485        if (finish_async(&async)) {
 486                err = error("external filter '%s' failed", cmd);
 487        }
 488
 489        if (!err) {
 490                strbuf_swap(dst, &nbuf);
 491        }
 492        strbuf_release(&nbuf);
 493        return !err;
 494}
 495
 496#define CAP_CLEAN    (1u<<0)
 497#define CAP_SMUDGE   (1u<<1)
 498
 499struct cmd2process {
 500        struct hashmap_entry ent; /* must be the first member! */
 501        unsigned int supported_capabilities;
 502        const char *cmd;
 503        struct child_process process;
 504};
 505
 506static int cmd_process_map_initialized;
 507static struct hashmap cmd_process_map;
 508
 509static int cmd2process_cmp(const struct cmd2process *e1,
 510                           const struct cmd2process *e2,
 511                           const void *unused)
 512{
 513        return strcmp(e1->cmd, e2->cmd);
 514}
 515
 516static struct cmd2process *find_multi_file_filter_entry(struct hashmap *hashmap, const char *cmd)
 517{
 518        struct cmd2process key;
 519        hashmap_entry_init(&key, strhash(cmd));
 520        key.cmd = cmd;
 521        return hashmap_get(hashmap, &key, NULL);
 522}
 523
 524static int packet_write_list(int fd, const char *line, ...)
 525{
 526        va_list args;
 527        int err;
 528        va_start(args, line);
 529        for (;;) {
 530                if (!line)
 531                        break;
 532                if (strlen(line) > LARGE_PACKET_DATA_MAX)
 533                        return -1;
 534                err = packet_write_fmt_gently(fd, "%s\n", line);
 535                if (err)
 536                        return err;
 537                line = va_arg(args, const char*);
 538        }
 539        va_end(args);
 540        return packet_flush_gently(fd);
 541}
 542
 543static void read_multi_file_filter_status(int fd, struct strbuf *status)
 544{
 545        struct strbuf **pair;
 546        char *line;
 547        for (;;) {
 548                line = packet_read_line(fd, NULL);
 549                if (!line)
 550                        break;
 551                pair = strbuf_split_str(line, '=', 2);
 552                if (pair[0] && pair[0]->len && pair[1]) {
 553                        /* the last "status=<foo>" line wins */
 554                        if (!strcmp(pair[0]->buf, "status=")) {
 555                                strbuf_reset(status);
 556                                strbuf_addbuf(status, pair[1]);
 557                        }
 558                }
 559                strbuf_list_free(pair);
 560        }
 561}
 562
 563static void kill_multi_file_filter(struct hashmap *hashmap, struct cmd2process *entry)
 564{
 565        if (!entry)
 566                return;
 567
 568        entry->process.clean_on_exit = 0;
 569        kill(entry->process.pid, SIGTERM);
 570        finish_command(&entry->process);
 571
 572        hashmap_remove(hashmap, entry, NULL);
 573        free(entry);
 574}
 575
 576static void stop_multi_file_filter(struct child_process *process)
 577{
 578        sigchain_push(SIGPIPE, SIG_IGN);
 579        /* Closing the pipe signals the filter to initiate a shutdown. */
 580        close(process->in);
 581        close(process->out);
 582        sigchain_pop(SIGPIPE);
 583        /* Finish command will wait until the shutdown is complete. */
 584        finish_command(process);
 585}
 586
 587static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, const char *cmd)
 588{
 589        int err;
 590        struct cmd2process *entry;
 591        struct child_process *process;
 592        const char *argv[] = { cmd, NULL };
 593        struct string_list cap_list = STRING_LIST_INIT_NODUP;
 594        char *cap_buf;
 595        const char *cap_name;
 596
 597        entry = xmalloc(sizeof(*entry));
 598        entry->cmd = cmd;
 599        entry->supported_capabilities = 0;
 600        process = &entry->process;
 601
 602        child_process_init(process);
 603        process->argv = argv;
 604        process->use_shell = 1;
 605        process->in = -1;
 606        process->out = -1;
 607        process->clean_on_exit = 1;
 608        process->clean_on_exit_handler = stop_multi_file_filter;
 609
 610        if (start_command(process)) {
 611                error("cannot fork to run external filter '%s'", cmd);
 612                return NULL;
 613        }
 614
 615        hashmap_entry_init(entry, strhash(cmd));
 616
 617        sigchain_push(SIGPIPE, SIG_IGN);
 618
 619        err = packet_write_list(process->in, "git-filter-client", "version=2", NULL);
 620        if (err)
 621                goto done;
 622
 623        err = strcmp(packet_read_line(process->out, NULL), "git-filter-server");
 624        if (err) {
 625                error("external filter '%s' does not support filter protocol version 2", cmd);
 626                goto done;
 627        }
 628        err = strcmp(packet_read_line(process->out, NULL), "version=2");
 629        if (err)
 630                goto done;
 631        err = packet_read_line(process->out, NULL) != NULL;
 632        if (err)
 633                goto done;
 634
 635        err = packet_write_list(process->in, "capability=clean", "capability=smudge", NULL);
 636
 637        for (;;) {
 638                cap_buf = packet_read_line(process->out, NULL);
 639                if (!cap_buf)
 640                        break;
 641                string_list_split_in_place(&cap_list, cap_buf, '=', 1);
 642
 643                if (cap_list.nr != 2 || strcmp(cap_list.items[0].string, "capability"))
 644                        continue;
 645
 646                cap_name = cap_list.items[1].string;
 647                if (!strcmp(cap_name, "clean")) {
 648                        entry->supported_capabilities |= CAP_CLEAN;
 649                } else if (!strcmp(cap_name, "smudge")) {
 650                        entry->supported_capabilities |= CAP_SMUDGE;
 651                } else {
 652                        warning(
 653                                "external filter '%s' requested unsupported filter capability '%s'",
 654                                cmd, cap_name
 655                        );
 656                }
 657
 658                string_list_clear(&cap_list, 0);
 659        }
 660
 661done:
 662        sigchain_pop(SIGPIPE);
 663
 664        if (err || errno == EPIPE) {
 665                error("initialization for external filter '%s' failed", cmd);
 666                kill_multi_file_filter(hashmap, entry);
 667                return NULL;
 668        }
 669
 670        hashmap_add(hashmap, entry);
 671        return entry;
 672}
 673
 674static int apply_multi_file_filter(const char *path, const char *src, size_t len,
 675                                   int fd, struct strbuf *dst, const char *cmd,
 676                                   const unsigned int wanted_capability)
 677{
 678        int err;
 679        struct cmd2process *entry;
 680        struct child_process *process;
 681        struct strbuf nbuf = STRBUF_INIT;
 682        struct strbuf filter_status = STRBUF_INIT;
 683        const char *filter_type;
 684
 685        if (!cmd_process_map_initialized) {
 686                cmd_process_map_initialized = 1;
 687                hashmap_init(&cmd_process_map, (hashmap_cmp_fn) cmd2process_cmp, 0);
 688                entry = NULL;
 689        } else {
 690                entry = find_multi_file_filter_entry(&cmd_process_map, cmd);
 691        }
 692
 693        fflush(NULL);
 694
 695        if (!entry) {
 696                entry = start_multi_file_filter(&cmd_process_map, cmd);
 697                if (!entry)
 698                        return 0;
 699        }
 700        process = &entry->process;
 701
 702        if (!(wanted_capability & entry->supported_capabilities))
 703                return 0;
 704
 705        if (CAP_CLEAN & wanted_capability)
 706                filter_type = "clean";
 707        else if (CAP_SMUDGE & wanted_capability)
 708                filter_type = "smudge";
 709        else
 710                die("unexpected filter type");
 711
 712        sigchain_push(SIGPIPE, SIG_IGN);
 713
 714        assert(strlen(filter_type) < LARGE_PACKET_DATA_MAX - strlen("command=\n"));
 715        err = packet_write_fmt_gently(process->in, "command=%s\n", filter_type);
 716        if (err)
 717                goto done;
 718
 719        err = strlen(path) > LARGE_PACKET_DATA_MAX - strlen("pathname=\n");
 720        if (err) {
 721                error("path name too long for external filter");
 722                goto done;
 723        }
 724
 725        err = packet_write_fmt_gently(process->in, "pathname=%s\n", path);
 726        if (err)
 727                goto done;
 728
 729        err = packet_flush_gently(process->in);
 730        if (err)
 731                goto done;
 732
 733        if (fd >= 0)
 734                err = write_packetized_from_fd(fd, process->in);
 735        else
 736                err = write_packetized_from_buf(src, len, process->in);
 737        if (err)
 738                goto done;
 739
 740        read_multi_file_filter_status(process->out, &filter_status);
 741        err = strcmp(filter_status.buf, "success");
 742        if (err)
 743                goto done;
 744
 745        err = read_packetized_to_strbuf(process->out, &nbuf) < 0;
 746        if (err)
 747                goto done;
 748
 749        read_multi_file_filter_status(process->out, &filter_status);
 750        err = strcmp(filter_status.buf, "success");
 751
 752done:
 753        sigchain_pop(SIGPIPE);
 754
 755        if (err || errno == EPIPE) {
 756                if (!strcmp(filter_status.buf, "error")) {
 757                        /* The filter signaled a problem with the file. */
 758                } else if (!strcmp(filter_status.buf, "abort")) {
 759                        /*
 760                         * The filter signaled a permanent problem. Don't try to filter
 761                         * files with the same command for the lifetime of the current
 762                         * Git process.
 763                         */
 764                         entry->supported_capabilities &= ~wanted_capability;
 765                } else {
 766                        /*
 767                         * Something went wrong with the protocol filter.
 768                         * Force shutdown and restart if another blob requires filtering.
 769                         */
 770                        error("external filter '%s' failed", cmd);
 771                        kill_multi_file_filter(&cmd_process_map, entry);
 772                }
 773        } else {
 774                strbuf_swap(dst, &nbuf);
 775        }
 776        strbuf_release(&nbuf);
 777        return !err;
 778}
 779
 780static struct convert_driver {
 781        const char *name;
 782        struct convert_driver *next;
 783        const char *smudge;
 784        const char *clean;
 785        const char *process;
 786        int required;
 787} *user_convert, **user_convert_tail;
 788
 789static int apply_filter(const char *path, const char *src, size_t len,
 790                        int fd, struct strbuf *dst, struct convert_driver *drv,
 791                        const unsigned int wanted_capability)
 792{
 793        const char *cmd = NULL;
 794
 795        if (!drv)
 796                return 0;
 797
 798        if (!dst)
 799                return 1;
 800
 801        if ((CAP_CLEAN & wanted_capability) && !drv->process && drv->clean)
 802                cmd = drv->clean;
 803        else if ((CAP_SMUDGE & wanted_capability) && !drv->process && drv->smudge)
 804                cmd = drv->smudge;
 805
 806        if (cmd && *cmd)
 807                return apply_single_file_filter(path, src, len, fd, dst, cmd);
 808        else if (drv->process && *drv->process)
 809                return apply_multi_file_filter(path, src, len, fd, dst, drv->process, wanted_capability);
 810
 811        return 0;
 812}
 813
 814static int read_convert_config(const char *var, const char *value, void *cb)
 815{
 816        const char *key, *name;
 817        int namelen;
 818        struct convert_driver *drv;
 819
 820        /*
 821         * External conversion drivers are configured using
 822         * "filter.<name>.variable".
 823         */
 824        if (parse_config_key(var, "filter", &name, &namelen, &key) < 0 || !name)
 825                return 0;
 826        for (drv = user_convert; drv; drv = drv->next)
 827                if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 828                        break;
 829        if (!drv) {
 830                drv = xcalloc(1, sizeof(struct convert_driver));
 831                drv->name = xmemdupz(name, namelen);
 832                *user_convert_tail = drv;
 833                user_convert_tail = &(drv->next);
 834        }
 835
 836        /*
 837         * filter.<name>.smudge and filter.<name>.clean specifies
 838         * the command line:
 839         *
 840         *      command-line
 841         *
 842         * The command-line will not be interpolated in any way.
 843         */
 844
 845        if (!strcmp("smudge", key))
 846                return git_config_string(&drv->smudge, var, value);
 847
 848        if (!strcmp("clean", key))
 849                return git_config_string(&drv->clean, var, value);
 850
 851        if (!strcmp("process", key))
 852                return git_config_string(&drv->process, var, value);
 853
 854        if (!strcmp("required", key)) {
 855                drv->required = git_config_bool(var, value);
 856                return 0;
 857        }
 858
 859        return 0;
 860}
 861
 862static int count_ident(const char *cp, unsigned long size)
 863{
 864        /*
 865         * "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
 866         */
 867        int cnt = 0;
 868        char ch;
 869
 870        while (size) {
 871                ch = *cp++;
 872                size--;
 873                if (ch != '$')
 874                        continue;
 875                if (size < 3)
 876                        break;
 877                if (memcmp("Id", cp, 2))
 878                        continue;
 879                ch = cp[2];
 880                cp += 3;
 881                size -= 3;
 882                if (ch == '$')
 883                        cnt++; /* $Id$ */
 884                if (ch != ':')
 885                        continue;
 886
 887                /*
 888                 * "$Id: ... "; scan up to the closing dollar sign and discard.
 889                 */
 890                while (size) {
 891                        ch = *cp++;
 892                        size--;
 893                        if (ch == '$') {
 894                                cnt++;
 895                                break;
 896                        }
 897                        if (ch == '\n')
 898                                break;
 899                }
 900        }
 901        return cnt;
 902}
 903
 904static int ident_to_git(const char *path, const char *src, size_t len,
 905                        struct strbuf *buf, int ident)
 906{
 907        char *dst, *dollar;
 908
 909        if (!ident || (src && !count_ident(src, len)))
 910                return 0;
 911
 912        if (!buf)
 913                return 1;
 914
 915        /* only grow if not in place */
 916        if (strbuf_avail(buf) + buf->len < len)
 917                strbuf_grow(buf, len - buf->len);
 918        dst = buf->buf;
 919        for (;;) {
 920                dollar = memchr(src, '$', len);
 921                if (!dollar)
 922                        break;
 923                memmove(dst, src, dollar + 1 - src);
 924                dst += dollar + 1 - src;
 925                len -= dollar + 1 - src;
 926                src  = dollar + 1;
 927
 928                if (len > 3 && !memcmp(src, "Id:", 3)) {
 929                        dollar = memchr(src + 3, '$', len - 3);
 930                        if (!dollar)
 931                                break;
 932                        if (memchr(src + 3, '\n', dollar - src - 3)) {
 933                                /* Line break before the next dollar. */
 934                                continue;
 935                        }
 936
 937                        memcpy(dst, "Id$", 3);
 938                        dst += 3;
 939                        len -= dollar + 1 - src;
 940                        src  = dollar + 1;
 941                }
 942        }
 943        memmove(dst, src, len);
 944        strbuf_setlen(buf, dst + len - buf->buf);
 945        return 1;
 946}
 947
 948static int ident_to_worktree(const char *path, const char *src, size_t len,
 949                             struct strbuf *buf, int ident)
 950{
 951        unsigned char sha1[20];
 952        char *to_free = NULL, *dollar, *spc;
 953        int cnt;
 954
 955        if (!ident)
 956                return 0;
 957
 958        cnt = count_ident(src, len);
 959        if (!cnt)
 960                return 0;
 961
 962        /* are we "faking" in place editing ? */
 963        if (src == buf->buf)
 964                to_free = strbuf_detach(buf, NULL);
 965        hash_sha1_file(src, len, "blob", sha1);
 966
 967        strbuf_grow(buf, len + cnt * 43);
 968        for (;;) {
 969                /* step 1: run to the next '$' */
 970                dollar = memchr(src, '$', len);
 971                if (!dollar)
 972                        break;
 973                strbuf_add(buf, src, dollar + 1 - src);
 974                len -= dollar + 1 - src;
 975                src  = dollar + 1;
 976
 977                /* step 2: does it looks like a bit like Id:xxx$ or Id$ ? */
 978                if (len < 3 || memcmp("Id", src, 2))
 979                        continue;
 980
 981                /* step 3: skip over Id$ or Id:xxxxx$ */
 982                if (src[2] == '$') {
 983                        src += 3;
 984                        len -= 3;
 985                } else if (src[2] == ':') {
 986                        /*
 987                         * It's possible that an expanded Id has crept its way into the
 988                         * repository, we cope with that by stripping the expansion out.
 989                         * This is probably not a good idea, since it will cause changes
 990                         * on checkout, which won't go away by stash, but let's keep it
 991                         * for git-style ids.
 992                         */
 993                        dollar = memchr(src + 3, '$', len - 3);
 994                        if (!dollar) {
 995                                /* incomplete keyword, no more '$', so just quit the loop */
 996                                break;
 997                        }
 998
 999                        if (memchr(src + 3, '\n', dollar - src - 3)) {
1000                                /* Line break before the next dollar. */
1001                                continue;
1002                        }
1003
1004                        spc = memchr(src + 4, ' ', dollar - src - 4);
1005                        if (spc && spc < dollar-1) {
1006                                /* There are spaces in unexpected places.
1007                                 * This is probably an id from some other
1008                                 * versioning system. Keep it for now.
1009                                 */
1010                                continue;
1011                        }
1012
1013                        len -= dollar + 1 - src;
1014                        src  = dollar + 1;
1015                } else {
1016                        /* it wasn't a "Id$" or "Id:xxxx$" */
1017                        continue;
1018                }
1019
1020                /* step 4: substitute */
1021                strbuf_addstr(buf, "Id: ");
1022                strbuf_add(buf, sha1_to_hex(sha1), 40);
1023                strbuf_addstr(buf, " $");
1024        }
1025        strbuf_add(buf, src, len);
1026
1027        free(to_free);
1028        return 1;
1029}
1030
1031static enum crlf_action git_path_check_crlf(struct attr_check_item *check)
1032{
1033        const char *value = check->value;
1034
1035        if (ATTR_TRUE(value))
1036                return CRLF_TEXT;
1037        else if (ATTR_FALSE(value))
1038                return CRLF_BINARY;
1039        else if (ATTR_UNSET(value))
1040                ;
1041        else if (!strcmp(value, "input"))
1042                return CRLF_TEXT_INPUT;
1043        else if (!strcmp(value, "auto"))
1044                return CRLF_AUTO;
1045        return CRLF_UNDEFINED;
1046}
1047
1048static enum eol git_path_check_eol(struct attr_check_item *check)
1049{
1050        const char *value = check->value;
1051
1052        if (ATTR_UNSET(value))
1053                ;
1054        else if (!strcmp(value, "lf"))
1055                return EOL_LF;
1056        else if (!strcmp(value, "crlf"))
1057                return EOL_CRLF;
1058        return EOL_UNSET;
1059}
1060
1061static struct convert_driver *git_path_check_convert(struct attr_check_item *check)
1062{
1063        const char *value = check->value;
1064        struct convert_driver *drv;
1065
1066        if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
1067                return NULL;
1068        for (drv = user_convert; drv; drv = drv->next)
1069                if (!strcmp(value, drv->name))
1070                        return drv;
1071        return NULL;
1072}
1073
1074static int git_path_check_ident(struct attr_check_item *check)
1075{
1076        const char *value = check->value;
1077
1078        return !!ATTR_TRUE(value);
1079}
1080
1081struct conv_attrs {
1082        struct convert_driver *drv;
1083        enum crlf_action attr_action; /* What attr says */
1084        enum crlf_action crlf_action; /* When no attr is set, use core.autocrlf */
1085        int ident;
1086};
1087
1088static void convert_attrs(struct conv_attrs *ca, const char *path)
1089{
1090        static struct attr_check *check;
1091
1092        if (!check) {
1093                check = attr_check_initl("crlf", "ident", "filter",
1094                                         "eol", "text", NULL);
1095                user_convert_tail = &user_convert;
1096                git_config(read_convert_config, NULL);
1097        }
1098
1099        if (!git_check_attr(path, check)) {
1100                struct attr_check_item *ccheck = check->items;
1101                ca->crlf_action = git_path_check_crlf(ccheck + 4);
1102                if (ca->crlf_action == CRLF_UNDEFINED)
1103                        ca->crlf_action = git_path_check_crlf(ccheck + 0);
1104                ca->attr_action = ca->crlf_action;
1105                ca->ident = git_path_check_ident(ccheck + 1);
1106                ca->drv = git_path_check_convert(ccheck + 2);
1107                if (ca->crlf_action != CRLF_BINARY) {
1108                        enum eol eol_attr = git_path_check_eol(ccheck + 3);
1109                        if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_LF)
1110                                ca->crlf_action = CRLF_AUTO_INPUT;
1111                        else if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_CRLF)
1112                                ca->crlf_action = CRLF_AUTO_CRLF;
1113                        else if (eol_attr == EOL_LF)
1114                                ca->crlf_action = CRLF_TEXT_INPUT;
1115                        else if (eol_attr == EOL_CRLF)
1116                                ca->crlf_action = CRLF_TEXT_CRLF;
1117                }
1118                ca->attr_action = ca->crlf_action;
1119        } else {
1120                ca->drv = NULL;
1121                ca->crlf_action = CRLF_UNDEFINED;
1122                ca->ident = 0;
1123        }
1124        if (ca->crlf_action == CRLF_TEXT)
1125                ca->crlf_action = text_eol_is_crlf() ? CRLF_TEXT_CRLF : CRLF_TEXT_INPUT;
1126        if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_FALSE)
1127                ca->crlf_action = CRLF_BINARY;
1128        if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_TRUE)
1129                ca->crlf_action = CRLF_AUTO_CRLF;
1130        if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_INPUT)
1131                ca->crlf_action = CRLF_AUTO_INPUT;
1132}
1133
1134int would_convert_to_git_filter_fd(const char *path)
1135{
1136        struct conv_attrs ca;
1137
1138        convert_attrs(&ca, path);
1139        if (!ca.drv)
1140                return 0;
1141
1142        /*
1143         * Apply a filter to an fd only if the filter is required to succeed.
1144         * We must die if the filter fails, because the original data before
1145         * filtering is not available.
1146         */
1147        if (!ca.drv->required)
1148                return 0;
1149
1150        return apply_filter(path, NULL, 0, -1, NULL, ca.drv, CAP_CLEAN);
1151}
1152
1153const char *get_convert_attr_ascii(const char *path)
1154{
1155        struct conv_attrs ca;
1156
1157        convert_attrs(&ca, path);
1158        switch (ca.attr_action) {
1159        case CRLF_UNDEFINED:
1160                return "";
1161        case CRLF_BINARY:
1162                return "-text";
1163        case CRLF_TEXT:
1164                return "text";
1165        case CRLF_TEXT_INPUT:
1166                return "text eol=lf";
1167        case CRLF_TEXT_CRLF:
1168                return "text eol=crlf";
1169        case CRLF_AUTO:
1170                return "text=auto";
1171        case CRLF_AUTO_CRLF:
1172                return "text=auto eol=crlf";
1173        case CRLF_AUTO_INPUT:
1174                return "text=auto eol=lf";
1175        }
1176        return "";
1177}
1178
1179int convert_to_git(const char *path, const char *src, size_t len,
1180                   struct strbuf *dst, enum safe_crlf checksafe)
1181{
1182        int ret = 0;
1183        struct conv_attrs ca;
1184
1185        convert_attrs(&ca, path);
1186
1187        ret |= apply_filter(path, src, len, -1, dst, ca.drv, CAP_CLEAN);
1188        if (!ret && ca.drv && ca.drv->required)
1189                die("%s: clean filter '%s' failed", path, ca.drv->name);
1190
1191        if (ret && dst) {
1192                src = dst->buf;
1193                len = dst->len;
1194        }
1195        ret |= crlf_to_git(path, src, len, dst, ca.crlf_action, checksafe);
1196        if (ret && dst) {
1197                src = dst->buf;
1198                len = dst->len;
1199        }
1200        return ret | ident_to_git(path, src, len, dst, ca.ident);
1201}
1202
1203void convert_to_git_filter_fd(const char *path, int fd, struct strbuf *dst,
1204                              enum safe_crlf checksafe)
1205{
1206        struct conv_attrs ca;
1207        convert_attrs(&ca, path);
1208
1209        assert(ca.drv);
1210        assert(ca.drv->clean || ca.drv->process);
1211
1212        if (!apply_filter(path, NULL, 0, fd, dst, ca.drv, CAP_CLEAN))
1213                die("%s: clean filter '%s' failed", path, ca.drv->name);
1214
1215        crlf_to_git(path, dst->buf, dst->len, dst, ca.crlf_action, checksafe);
1216        ident_to_git(path, dst->buf, dst->len, dst, ca.ident);
1217}
1218
1219static int convert_to_working_tree_internal(const char *path, const char *src,
1220                                            size_t len, struct strbuf *dst,
1221                                            int normalizing)
1222{
1223        int ret = 0, ret_filter = 0;
1224        struct conv_attrs ca;
1225
1226        convert_attrs(&ca, path);
1227
1228        ret |= ident_to_worktree(path, src, len, dst, ca.ident);
1229        if (ret) {
1230                src = dst->buf;
1231                len = dst->len;
1232        }
1233        /*
1234         * CRLF conversion can be skipped if normalizing, unless there
1235         * is a smudge or process filter (even if the process filter doesn't
1236         * support smudge).  The filters might expect CRLFs.
1237         */
1238        if ((ca.drv && (ca.drv->smudge || ca.drv->process)) || !normalizing) {
1239                ret |= crlf_to_worktree(path, src, len, dst, ca.crlf_action);
1240                if (ret) {
1241                        src = dst->buf;
1242                        len = dst->len;
1243                }
1244        }
1245
1246        ret_filter = apply_filter(path, src, len, -1, dst, ca.drv, CAP_SMUDGE);
1247        if (!ret_filter && ca.drv && ca.drv->required)
1248                die("%s: smudge filter %s failed", path, ca.drv->name);
1249
1250        return ret | ret_filter;
1251}
1252
1253int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst)
1254{
1255        return convert_to_working_tree_internal(path, src, len, dst, 0);
1256}
1257
1258int renormalize_buffer(const char *path, const char *src, size_t len, struct strbuf *dst)
1259{
1260        int ret = convert_to_working_tree_internal(path, src, len, dst, 1);
1261        if (ret) {
1262                src = dst->buf;
1263                len = dst->len;
1264        }
1265        return ret | convert_to_git(path, src, len, dst, SAFE_CRLF_RENORMALIZE);
1266}
1267
1268/*****************************************************************
1269 *
1270 * Streaming conversion support
1271 *
1272 *****************************************************************/
1273
1274typedef int (*filter_fn)(struct stream_filter *,
1275                         const char *input, size_t *isize_p,
1276                         char *output, size_t *osize_p);
1277typedef void (*free_fn)(struct stream_filter *);
1278
1279struct stream_filter_vtbl {
1280        filter_fn filter;
1281        free_fn free;
1282};
1283
1284struct stream_filter {
1285        struct stream_filter_vtbl *vtbl;
1286};
1287
1288static int null_filter_fn(struct stream_filter *filter,
1289                          const char *input, size_t *isize_p,
1290                          char *output, size_t *osize_p)
1291{
1292        size_t count;
1293
1294        if (!input)
1295                return 0; /* we do not keep any states */
1296        count = *isize_p;
1297        if (*osize_p < count)
1298                count = *osize_p;
1299        if (count) {
1300                memmove(output, input, count);
1301                *isize_p -= count;
1302                *osize_p -= count;
1303        }
1304        return 0;
1305}
1306
1307static void null_free_fn(struct stream_filter *filter)
1308{
1309        ; /* nothing -- null instances are shared */
1310}
1311
1312static struct stream_filter_vtbl null_vtbl = {
1313        null_filter_fn,
1314        null_free_fn,
1315};
1316
1317static struct stream_filter null_filter_singleton = {
1318        &null_vtbl,
1319};
1320
1321int is_null_stream_filter(struct stream_filter *filter)
1322{
1323        return filter == &null_filter_singleton;
1324}
1325
1326
1327/*
1328 * LF-to-CRLF filter
1329 */
1330
1331struct lf_to_crlf_filter {
1332        struct stream_filter filter;
1333        unsigned has_held:1;
1334        char held;
1335};
1336
1337static int lf_to_crlf_filter_fn(struct stream_filter *filter,
1338                                const char *input, size_t *isize_p,
1339                                char *output, size_t *osize_p)
1340{
1341        size_t count, o = 0;
1342        struct lf_to_crlf_filter *lf_to_crlf = (struct lf_to_crlf_filter *)filter;
1343
1344        /*
1345         * We may be holding onto the CR to see if it is followed by a
1346         * LF, in which case we would need to go to the main loop.
1347         * Otherwise, just emit it to the output stream.
1348         */
1349        if (lf_to_crlf->has_held && (lf_to_crlf->held != '\r' || !input)) {
1350                output[o++] = lf_to_crlf->held;
1351                lf_to_crlf->has_held = 0;
1352        }
1353
1354        /* We are told to drain */
1355        if (!input) {
1356                *osize_p -= o;
1357                return 0;
1358        }
1359
1360        count = *isize_p;
1361        if (count || lf_to_crlf->has_held) {
1362                size_t i;
1363                int was_cr = 0;
1364
1365                if (lf_to_crlf->has_held) {
1366                        was_cr = 1;
1367                        lf_to_crlf->has_held = 0;
1368                }
1369
1370                for (i = 0; o < *osize_p && i < count; i++) {
1371                        char ch = input[i];
1372
1373                        if (ch == '\n') {
1374                                output[o++] = '\r';
1375                        } else if (was_cr) {
1376                                /*
1377                                 * Previous round saw CR and it is not followed
1378                                 * by a LF; emit the CR before processing the
1379                                 * current character.
1380                                 */
1381                                output[o++] = '\r';
1382                        }
1383
1384                        /*
1385                         * We may have consumed the last output slot,
1386                         * in which case we need to break out of this
1387                         * loop; hold the current character before
1388                         * returning.
1389                         */
1390                        if (*osize_p <= o) {
1391                                lf_to_crlf->has_held = 1;
1392                                lf_to_crlf->held = ch;
1393                                continue; /* break but increment i */
1394                        }
1395
1396                        if (ch == '\r') {
1397                                was_cr = 1;
1398                                continue;
1399                        }
1400
1401                        was_cr = 0;
1402                        output[o++] = ch;
1403                }
1404
1405                *osize_p -= o;
1406                *isize_p -= i;
1407
1408                if (!lf_to_crlf->has_held && was_cr) {
1409                        lf_to_crlf->has_held = 1;
1410                        lf_to_crlf->held = '\r';
1411                }
1412        }
1413        return 0;
1414}
1415
1416static void lf_to_crlf_free_fn(struct stream_filter *filter)
1417{
1418        free(filter);
1419}
1420
1421static struct stream_filter_vtbl lf_to_crlf_vtbl = {
1422        lf_to_crlf_filter_fn,
1423        lf_to_crlf_free_fn,
1424};
1425
1426static struct stream_filter *lf_to_crlf_filter(void)
1427{
1428        struct lf_to_crlf_filter *lf_to_crlf = xcalloc(1, sizeof(*lf_to_crlf));
1429
1430        lf_to_crlf->filter.vtbl = &lf_to_crlf_vtbl;
1431        return (struct stream_filter *)lf_to_crlf;
1432}
1433
1434/*
1435 * Cascade filter
1436 */
1437#define FILTER_BUFFER 1024
1438struct cascade_filter {
1439        struct stream_filter filter;
1440        struct stream_filter *one;
1441        struct stream_filter *two;
1442        char buf[FILTER_BUFFER];
1443        int end, ptr;
1444};
1445
1446static int cascade_filter_fn(struct stream_filter *filter,
1447                             const char *input, size_t *isize_p,
1448                             char *output, size_t *osize_p)
1449{
1450        struct cascade_filter *cas = (struct cascade_filter *) filter;
1451        size_t filled = 0;
1452        size_t sz = *osize_p;
1453        size_t to_feed, remaining;
1454
1455        /*
1456         * input -- (one) --> buf -- (two) --> output
1457         */
1458        while (filled < sz) {
1459                remaining = sz - filled;
1460
1461                /* do we already have something to feed two with? */
1462                if (cas->ptr < cas->end) {
1463                        to_feed = cas->end - cas->ptr;
1464                        if (stream_filter(cas->two,
1465                                          cas->buf + cas->ptr, &to_feed,
1466                                          output + filled, &remaining))
1467                                return -1;
1468                        cas->ptr += (cas->end - cas->ptr) - to_feed;
1469                        filled = sz - remaining;
1470                        continue;
1471                }
1472
1473                /* feed one from upstream and have it emit into our buffer */
1474                to_feed = input ? *isize_p : 0;
1475                if (input && !to_feed)
1476                        break;
1477                remaining = sizeof(cas->buf);
1478                if (stream_filter(cas->one,
1479                                  input, &to_feed,
1480                                  cas->buf, &remaining))
1481                        return -1;
1482                cas->end = sizeof(cas->buf) - remaining;
1483                cas->ptr = 0;
1484                if (input) {
1485                        size_t fed = *isize_p - to_feed;
1486                        *isize_p -= fed;
1487                        input += fed;
1488                }
1489
1490                /* do we know that we drained one completely? */
1491                if (input || cas->end)
1492                        continue;
1493
1494                /* tell two to drain; we have nothing more to give it */
1495                to_feed = 0;
1496                remaining = sz - filled;
1497                if (stream_filter(cas->two,
1498                                  NULL, &to_feed,
1499                                  output + filled, &remaining))
1500                        return -1;
1501                if (remaining == (sz - filled))
1502                        break; /* completely drained two */
1503                filled = sz - remaining;
1504        }
1505        *osize_p -= filled;
1506        return 0;
1507}
1508
1509static void cascade_free_fn(struct stream_filter *filter)
1510{
1511        struct cascade_filter *cas = (struct cascade_filter *)filter;
1512        free_stream_filter(cas->one);
1513        free_stream_filter(cas->two);
1514        free(filter);
1515}
1516
1517static struct stream_filter_vtbl cascade_vtbl = {
1518        cascade_filter_fn,
1519        cascade_free_fn,
1520};
1521
1522static struct stream_filter *cascade_filter(struct stream_filter *one,
1523                                            struct stream_filter *two)
1524{
1525        struct cascade_filter *cascade;
1526
1527        if (!one || is_null_stream_filter(one))
1528                return two;
1529        if (!two || is_null_stream_filter(two))
1530                return one;
1531
1532        cascade = xmalloc(sizeof(*cascade));
1533        cascade->one = one;
1534        cascade->two = two;
1535        cascade->end = cascade->ptr = 0;
1536        cascade->filter.vtbl = &cascade_vtbl;
1537        return (struct stream_filter *)cascade;
1538}
1539
1540/*
1541 * ident filter
1542 */
1543#define IDENT_DRAINING (-1)
1544#define IDENT_SKIPPING (-2)
1545struct ident_filter {
1546        struct stream_filter filter;
1547        struct strbuf left;
1548        int state;
1549        char ident[45]; /* ": x40 $" */
1550};
1551
1552static int is_foreign_ident(const char *str)
1553{
1554        int i;
1555
1556        if (!skip_prefix(str, "$Id: ", &str))
1557                return 0;
1558        for (i = 0; str[i]; i++) {
1559                if (isspace(str[i]) && str[i+1] != '$')
1560                        return 1;
1561        }
1562        return 0;
1563}
1564
1565static void ident_drain(struct ident_filter *ident, char **output_p, size_t *osize_p)
1566{
1567        size_t to_drain = ident->left.len;
1568
1569        if (*osize_p < to_drain)
1570                to_drain = *osize_p;
1571        if (to_drain) {
1572                memcpy(*output_p, ident->left.buf, to_drain);
1573                strbuf_remove(&ident->left, 0, to_drain);
1574                *output_p += to_drain;
1575                *osize_p -= to_drain;
1576        }
1577        if (!ident->left.len)
1578                ident->state = 0;
1579}
1580
1581static int ident_filter_fn(struct stream_filter *filter,
1582                           const char *input, size_t *isize_p,
1583                           char *output, size_t *osize_p)
1584{
1585        struct ident_filter *ident = (struct ident_filter *)filter;
1586        static const char head[] = "$Id";
1587
1588        if (!input) {
1589                /* drain upon eof */
1590                switch (ident->state) {
1591                default:
1592                        strbuf_add(&ident->left, head, ident->state);
1593                case IDENT_SKIPPING:
1594                        /* fallthru */
1595                case IDENT_DRAINING:
1596                        ident_drain(ident, &output, osize_p);
1597                }
1598                return 0;
1599        }
1600
1601        while (*isize_p || (ident->state == IDENT_DRAINING)) {
1602                int ch;
1603
1604                if (ident->state == IDENT_DRAINING) {
1605                        ident_drain(ident, &output, osize_p);
1606                        if (!*osize_p)
1607                                break;
1608                        continue;
1609                }
1610
1611                ch = *(input++);
1612                (*isize_p)--;
1613
1614                if (ident->state == IDENT_SKIPPING) {
1615                        /*
1616                         * Skipping until '$' or LF, but keeping them
1617                         * in case it is a foreign ident.
1618                         */
1619                        strbuf_addch(&ident->left, ch);
1620                        if (ch != '\n' && ch != '$')
1621                                continue;
1622                        if (ch == '$' && !is_foreign_ident(ident->left.buf)) {
1623                                strbuf_setlen(&ident->left, sizeof(head) - 1);
1624                                strbuf_addstr(&ident->left, ident->ident);
1625                        }
1626                        ident->state = IDENT_DRAINING;
1627                        continue;
1628                }
1629
1630                if (ident->state < sizeof(head) &&
1631                    head[ident->state] == ch) {
1632                        ident->state++;
1633                        continue;
1634                }
1635
1636                if (ident->state)
1637                        strbuf_add(&ident->left, head, ident->state);
1638                if (ident->state == sizeof(head) - 1) {
1639                        if (ch != ':' && ch != '$') {
1640                                strbuf_addch(&ident->left, ch);
1641                                ident->state = 0;
1642                                continue;
1643                        }
1644
1645                        if (ch == ':') {
1646                                strbuf_addch(&ident->left, ch);
1647                                ident->state = IDENT_SKIPPING;
1648                        } else {
1649                                strbuf_addstr(&ident->left, ident->ident);
1650                                ident->state = IDENT_DRAINING;
1651                        }
1652                        continue;
1653                }
1654
1655                strbuf_addch(&ident->left, ch);
1656                ident->state = IDENT_DRAINING;
1657        }
1658        return 0;
1659}
1660
1661static void ident_free_fn(struct stream_filter *filter)
1662{
1663        struct ident_filter *ident = (struct ident_filter *)filter;
1664        strbuf_release(&ident->left);
1665        free(filter);
1666}
1667
1668static struct stream_filter_vtbl ident_vtbl = {
1669        ident_filter_fn,
1670        ident_free_fn,
1671};
1672
1673static struct stream_filter *ident_filter(const unsigned char *sha1)
1674{
1675        struct ident_filter *ident = xmalloc(sizeof(*ident));
1676
1677        xsnprintf(ident->ident, sizeof(ident->ident),
1678                  ": %s $", sha1_to_hex(sha1));
1679        strbuf_init(&ident->left, 0);
1680        ident->filter.vtbl = &ident_vtbl;
1681        ident->state = 0;
1682        return (struct stream_filter *)ident;
1683}
1684
1685/*
1686 * Return an appropriately constructed filter for the path, or NULL if
1687 * the contents cannot be filtered without reading the whole thing
1688 * in-core.
1689 *
1690 * Note that you would be crazy to set CRLF, smuge/clean or ident to a
1691 * large binary blob you would want us not to slurp into the memory!
1692 */
1693struct stream_filter *get_stream_filter(const char *path, const unsigned char *sha1)
1694{
1695        struct conv_attrs ca;
1696        struct stream_filter *filter = NULL;
1697
1698        convert_attrs(&ca, path);
1699        if (ca.drv && (ca.drv->process || ca.drv->smudge || ca.drv->clean))
1700                return NULL;
1701
1702        if (ca.crlf_action == CRLF_AUTO || ca.crlf_action == CRLF_AUTO_CRLF)
1703                return NULL;
1704
1705        if (ca.ident)
1706                filter = ident_filter(sha1);
1707
1708        if (output_eol(ca.crlf_action) == EOL_CRLF)
1709                filter = cascade_filter(filter, lf_to_crlf_filter());
1710        else
1711                filter = cascade_filter(filter, &null_filter_singleton);
1712
1713        return filter;
1714}
1715
1716void free_stream_filter(struct stream_filter *filter)
1717{
1718        filter->vtbl->free(filter);
1719}
1720
1721int stream_filter(struct stream_filter *filter,
1722                  const char *input, size_t *isize_p,
1723                  char *output, size_t *osize_p)
1724{
1725        return filter->vtbl->filter(filter, input, isize_p, output, osize_p);
1726}