convert.con commit commit: allow lookup_commit_graft to handle arbitrary repositories (b9dbddf)
   1#define NO_THE_INDEX_COMPATIBILITY_MACROS
   2#include "cache.h"
   3#include "config.h"
   4#include "object-store.h"
   5#include "attr.h"
   6#include "run-command.h"
   7#include "quote.h"
   8#include "sigchain.h"
   9#include "pkt-line.h"
  10#include "sub-process.h"
  11
  12/*
  13 * convert.c - convert a file when checking it out and checking it in.
  14 *
  15 * This should use the pathname to decide on whether it wants to do some
  16 * more interesting conversions (automatic gzip/unzip, general format
  17 * conversions etc etc), but by default it just does automatic CRLF<->LF
  18 * translation when the "text" attribute or "auto_crlf" option is set.
  19 */
  20
  21/* Stat bits: When BIN is set, the txt bits are unset */
  22#define CONVERT_STAT_BITS_TXT_LF    0x1
  23#define CONVERT_STAT_BITS_TXT_CRLF  0x2
  24#define CONVERT_STAT_BITS_BIN       0x4
  25
  26enum crlf_action {
  27        CRLF_UNDEFINED,
  28        CRLF_BINARY,
  29        CRLF_TEXT,
  30        CRLF_TEXT_INPUT,
  31        CRLF_TEXT_CRLF,
  32        CRLF_AUTO,
  33        CRLF_AUTO_INPUT,
  34        CRLF_AUTO_CRLF
  35};
  36
  37struct text_stat {
  38        /* NUL, CR, LF and CRLF counts */
  39        unsigned nul, lonecr, lonelf, crlf;
  40
  41        /* These are just approximations! */
  42        unsigned printable, nonprintable;
  43};
  44
  45static void gather_stats(const char *buf, unsigned long size, struct text_stat *stats)
  46{
  47        unsigned long i;
  48
  49        memset(stats, 0, sizeof(*stats));
  50
  51        for (i = 0; i < size; i++) {
  52                unsigned char c = buf[i];
  53                if (c == '\r') {
  54                        if (i+1 < size && buf[i+1] == '\n') {
  55                                stats->crlf++;
  56                                i++;
  57                        } else
  58                                stats->lonecr++;
  59                        continue;
  60                }
  61                if (c == '\n') {
  62                        stats->lonelf++;
  63                        continue;
  64                }
  65                if (c == 127)
  66                        /* DEL */
  67                        stats->nonprintable++;
  68                else if (c < 32) {
  69                        switch (c) {
  70                                /* BS, HT, ESC and FF */
  71                        case '\b': case '\t': case '\033': case '\014':
  72                                stats->printable++;
  73                                break;
  74                        case 0:
  75                                stats->nul++;
  76                                /* fall through */
  77                        default:
  78                                stats->nonprintable++;
  79                        }
  80                }
  81                else
  82                        stats->printable++;
  83        }
  84
  85        /* If file ends with EOF then don't count this EOF as non-printable. */
  86        if (size >= 1 && buf[size-1] == '\032')
  87                stats->nonprintable--;
  88}
  89
  90/*
  91 * The same heuristics as diff.c::mmfile_is_binary()
  92 * We treat files with bare CR as binary
  93 */
  94static int convert_is_binary(unsigned long size, const struct text_stat *stats)
  95{
  96        if (stats->lonecr)
  97                return 1;
  98        if (stats->nul)
  99                return 1;
 100        if ((stats->printable >> 7) < stats->nonprintable)
 101                return 1;
 102        return 0;
 103}
 104
 105static unsigned int gather_convert_stats(const char *data, unsigned long size)
 106{
 107        struct text_stat stats;
 108        int ret = 0;
 109        if (!data || !size)
 110                return 0;
 111        gather_stats(data, size, &stats);
 112        if (convert_is_binary(size, &stats))
 113                ret |= CONVERT_STAT_BITS_BIN;
 114        if (stats.crlf)
 115                ret |= CONVERT_STAT_BITS_TXT_CRLF;
 116        if (stats.lonelf)
 117                ret |=  CONVERT_STAT_BITS_TXT_LF;
 118
 119        return ret;
 120}
 121
 122static const char *gather_convert_stats_ascii(const char *data, unsigned long size)
 123{
 124        unsigned int convert_stats = gather_convert_stats(data, size);
 125
 126        if (convert_stats & CONVERT_STAT_BITS_BIN)
 127                return "-text";
 128        switch (convert_stats) {
 129        case CONVERT_STAT_BITS_TXT_LF:
 130                return "lf";
 131        case CONVERT_STAT_BITS_TXT_CRLF:
 132                return "crlf";
 133        case CONVERT_STAT_BITS_TXT_LF | CONVERT_STAT_BITS_TXT_CRLF:
 134                return "mixed";
 135        default:
 136                return "none";
 137        }
 138}
 139
 140const char *get_cached_convert_stats_ascii(const struct index_state *istate,
 141                                           const char *path)
 142{
 143        const char *ret;
 144        unsigned long sz;
 145        void *data = read_blob_data_from_index(istate, path, &sz);
 146        ret = gather_convert_stats_ascii(data, sz);
 147        free(data);
 148        return ret;
 149}
 150
 151const char *get_wt_convert_stats_ascii(const char *path)
 152{
 153        const char *ret = "";
 154        struct strbuf sb = STRBUF_INIT;
 155        if (strbuf_read_file(&sb, path, 0) >= 0)
 156                ret = gather_convert_stats_ascii(sb.buf, sb.len);
 157        strbuf_release(&sb);
 158        return ret;
 159}
 160
 161static int text_eol_is_crlf(void)
 162{
 163        if (auto_crlf == AUTO_CRLF_TRUE)
 164                return 1;
 165        else if (auto_crlf == AUTO_CRLF_INPUT)
 166                return 0;
 167        if (core_eol == EOL_CRLF)
 168                return 1;
 169        if (core_eol == EOL_UNSET && EOL_NATIVE == EOL_CRLF)
 170                return 1;
 171        return 0;
 172}
 173
 174static enum eol output_eol(enum crlf_action crlf_action)
 175{
 176        switch (crlf_action) {
 177        case CRLF_BINARY:
 178                return EOL_UNSET;
 179        case CRLF_TEXT_CRLF:
 180                return EOL_CRLF;
 181        case CRLF_TEXT_INPUT:
 182                return EOL_LF;
 183        case CRLF_UNDEFINED:
 184        case CRLF_AUTO_CRLF:
 185                return EOL_CRLF;
 186        case CRLF_AUTO_INPUT:
 187                return EOL_LF;
 188        case CRLF_TEXT:
 189        case CRLF_AUTO:
 190                /* fall through */
 191                return text_eol_is_crlf() ? EOL_CRLF : EOL_LF;
 192        }
 193        warning("Illegal crlf_action %d\n", (int)crlf_action);
 194        return core_eol;
 195}
 196
 197static void check_global_conv_flags_eol(const char *path, enum crlf_action crlf_action,
 198                            struct text_stat *old_stats, struct text_stat *new_stats,
 199                            int conv_flags)
 200{
 201        if (old_stats->crlf && !new_stats->crlf ) {
 202                /*
 203                 * CRLFs would not be restored by checkout
 204                 */
 205                if (conv_flags & CONV_EOL_RNDTRP_DIE)
 206                        die(_("CRLF would be replaced by LF in %s."), path);
 207                else if (conv_flags & CONV_EOL_RNDTRP_WARN)
 208                        warning(_("CRLF will be replaced by LF in %s.\n"
 209                                  "The file will have its original line"
 210                                  " endings in your working directory."), path);
 211        } else if (old_stats->lonelf && !new_stats->lonelf ) {
 212                /*
 213                 * CRLFs would be added by checkout
 214                 */
 215                if (conv_flags & CONV_EOL_RNDTRP_DIE)
 216                        die(_("LF would be replaced by CRLF in %s"), path);
 217                else if (conv_flags & CONV_EOL_RNDTRP_WARN)
 218                        warning(_("LF will be replaced by CRLF in %s.\n"
 219                                  "The file will have its original line"
 220                                  " endings in your working directory."), path);
 221        }
 222}
 223
 224static int has_crlf_in_index(const struct index_state *istate, const char *path)
 225{
 226        unsigned long sz;
 227        void *data;
 228        const char *crp;
 229        int has_crlf = 0;
 230
 231        data = read_blob_data_from_index(istate, path, &sz);
 232        if (!data)
 233                return 0;
 234
 235        crp = memchr(data, '\r', sz);
 236        if (crp) {
 237                unsigned int ret_stats;
 238                ret_stats = gather_convert_stats(data, sz);
 239                if (!(ret_stats & CONVERT_STAT_BITS_BIN) &&
 240                    (ret_stats & CONVERT_STAT_BITS_TXT_CRLF))
 241                        has_crlf = 1;
 242        }
 243        free(data);
 244        return has_crlf;
 245}
 246
 247static int will_convert_lf_to_crlf(size_t len, struct text_stat *stats,
 248                                   enum crlf_action crlf_action)
 249{
 250        if (output_eol(crlf_action) != EOL_CRLF)
 251                return 0;
 252        /* No "naked" LF? Nothing to convert, regardless. */
 253        if (!stats->lonelf)
 254                return 0;
 255
 256        if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 257                /* If we have any CR or CRLF line endings, we do not touch it */
 258                /* This is the new safer autocrlf-handling */
 259                if (stats->lonecr || stats->crlf)
 260                        return 0;
 261
 262                if (convert_is_binary(len, stats))
 263                        return 0;
 264        }
 265        return 1;
 266
 267}
 268
 269static int crlf_to_git(const struct index_state *istate,
 270                       const char *path, const char *src, size_t len,
 271                       struct strbuf *buf,
 272                       enum crlf_action crlf_action, int conv_flags)
 273{
 274        struct text_stat stats;
 275        char *dst;
 276        int convert_crlf_into_lf;
 277
 278        if (crlf_action == CRLF_BINARY ||
 279            (src && !len))
 280                return 0;
 281
 282        /*
 283         * If we are doing a dry-run and have no source buffer, there is
 284         * nothing to analyze; we must assume we would convert.
 285         */
 286        if (!buf && !src)
 287                return 1;
 288
 289        gather_stats(src, len, &stats);
 290        /* Optimization: No CRLF? Nothing to convert, regardless. */
 291        convert_crlf_into_lf = !!stats.crlf;
 292
 293        if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 294                if (convert_is_binary(len, &stats))
 295                        return 0;
 296                /*
 297                 * If the file in the index has any CR in it, do not
 298                 * convert.  This is the new safer autocrlf handling,
 299                 * unless we want to renormalize in a merge or
 300                 * cherry-pick.
 301                 */
 302                if ((!(conv_flags & CONV_EOL_RENORMALIZE)) &&
 303                    has_crlf_in_index(istate, path))
 304                        convert_crlf_into_lf = 0;
 305        }
 306        if (((conv_flags & CONV_EOL_RNDTRP_WARN) ||
 307             ((conv_flags & CONV_EOL_RNDTRP_DIE) && len))) {
 308                struct text_stat new_stats;
 309                memcpy(&new_stats, &stats, sizeof(new_stats));
 310                /* simulate "git add" */
 311                if (convert_crlf_into_lf) {
 312                        new_stats.lonelf += new_stats.crlf;
 313                        new_stats.crlf = 0;
 314                }
 315                /* simulate "git checkout" */
 316                if (will_convert_lf_to_crlf(len, &new_stats, crlf_action)) {
 317                        new_stats.crlf += new_stats.lonelf;
 318                        new_stats.lonelf = 0;
 319                }
 320                check_global_conv_flags_eol(path, crlf_action, &stats, &new_stats, conv_flags);
 321        }
 322        if (!convert_crlf_into_lf)
 323                return 0;
 324
 325        /*
 326         * At this point all of our source analysis is done, and we are sure we
 327         * would convert. If we are in dry-run mode, we can give an answer.
 328         */
 329        if (!buf)
 330                return 1;
 331
 332        /* only grow if not in place */
 333        if (strbuf_avail(buf) + buf->len < len)
 334                strbuf_grow(buf, len - buf->len);
 335        dst = buf->buf;
 336        if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
 337                /*
 338                 * If we guessed, we already know we rejected a file with
 339                 * lone CR, and we can strip a CR without looking at what
 340                 * follow it.
 341                 */
 342                do {
 343                        unsigned char c = *src++;
 344                        if (c != '\r')
 345                                *dst++ = c;
 346                } while (--len);
 347        } else {
 348                do {
 349                        unsigned char c = *src++;
 350                        if (! (c == '\r' && (1 < len && *src == '\n')))
 351                                *dst++ = c;
 352                } while (--len);
 353        }
 354        strbuf_setlen(buf, dst - buf->buf);
 355        return 1;
 356}
 357
 358static int crlf_to_worktree(const char *path, const char *src, size_t len,
 359                            struct strbuf *buf, enum crlf_action crlf_action)
 360{
 361        char *to_free = NULL;
 362        struct text_stat stats;
 363
 364        if (!len || output_eol(crlf_action) != EOL_CRLF)
 365                return 0;
 366
 367        gather_stats(src, len, &stats);
 368        if (!will_convert_lf_to_crlf(len, &stats, crlf_action))
 369                return 0;
 370
 371        /* are we "faking" in place editing ? */
 372        if (src == buf->buf)
 373                to_free = strbuf_detach(buf, NULL);
 374
 375        strbuf_grow(buf, len + stats.lonelf);
 376        for (;;) {
 377                const char *nl = memchr(src, '\n', len);
 378                if (!nl)
 379                        break;
 380                if (nl > src && nl[-1] == '\r') {
 381                        strbuf_add(buf, src, nl + 1 - src);
 382                } else {
 383                        strbuf_add(buf, src, nl - src);
 384                        strbuf_addstr(buf, "\r\n");
 385                }
 386                len -= nl + 1 - src;
 387                src  = nl + 1;
 388        }
 389        strbuf_add(buf, src, len);
 390
 391        free(to_free);
 392        return 1;
 393}
 394
 395struct filter_params {
 396        const char *src;
 397        unsigned long size;
 398        int fd;
 399        const char *cmd;
 400        const char *path;
 401};
 402
 403static int filter_buffer_or_fd(int in, int out, void *data)
 404{
 405        /*
 406         * Spawn cmd and feed the buffer contents through its stdin.
 407         */
 408        struct child_process child_process = CHILD_PROCESS_INIT;
 409        struct filter_params *params = (struct filter_params *)data;
 410        int write_err, status;
 411        const char *argv[] = { NULL, NULL };
 412
 413        /* apply % substitution to cmd */
 414        struct strbuf cmd = STRBUF_INIT;
 415        struct strbuf path = STRBUF_INIT;
 416        struct strbuf_expand_dict_entry dict[] = {
 417                { "f", NULL, },
 418                { NULL, NULL, },
 419        };
 420
 421        /* quote the path to preserve spaces, etc. */
 422        sq_quote_buf(&path, params->path);
 423        dict[0].value = path.buf;
 424
 425        /* expand all %f with the quoted path */
 426        strbuf_expand(&cmd, params->cmd, strbuf_expand_dict_cb, &dict);
 427        strbuf_release(&path);
 428
 429        argv[0] = cmd.buf;
 430
 431        child_process.argv = argv;
 432        child_process.use_shell = 1;
 433        child_process.in = -1;
 434        child_process.out = out;
 435
 436        if (start_command(&child_process)) {
 437                strbuf_release(&cmd);
 438                return error("cannot fork to run external filter '%s'", params->cmd);
 439        }
 440
 441        sigchain_push(SIGPIPE, SIG_IGN);
 442
 443        if (params->src) {
 444                write_err = (write_in_full(child_process.in,
 445                                           params->src, params->size) < 0);
 446                if (errno == EPIPE)
 447                        write_err = 0;
 448        } else {
 449                write_err = copy_fd(params->fd, child_process.in);
 450                if (write_err == COPY_WRITE_ERROR && errno == EPIPE)
 451                        write_err = 0;
 452        }
 453
 454        if (close(child_process.in))
 455                write_err = 1;
 456        if (write_err)
 457                error("cannot feed the input to external filter '%s'", params->cmd);
 458
 459        sigchain_pop(SIGPIPE);
 460
 461        status = finish_command(&child_process);
 462        if (status)
 463                error("external filter '%s' failed %d", params->cmd, status);
 464
 465        strbuf_release(&cmd);
 466        return (write_err || status);
 467}
 468
 469static int apply_single_file_filter(const char *path, const char *src, size_t len, int fd,
 470                        struct strbuf *dst, const char *cmd)
 471{
 472        /*
 473         * Create a pipeline to have the command filter the buffer's
 474         * contents.
 475         *
 476         * (child --> cmd) --> us
 477         */
 478        int err = 0;
 479        struct strbuf nbuf = STRBUF_INIT;
 480        struct async async;
 481        struct filter_params params;
 482
 483        memset(&async, 0, sizeof(async));
 484        async.proc = filter_buffer_or_fd;
 485        async.data = &params;
 486        async.out = -1;
 487        params.src = src;
 488        params.size = len;
 489        params.fd = fd;
 490        params.cmd = cmd;
 491        params.path = path;
 492
 493        fflush(NULL);
 494        if (start_async(&async))
 495                return 0;       /* error was already reported */
 496
 497        if (strbuf_read(&nbuf, async.out, len) < 0) {
 498                err = error("read from external filter '%s' failed", cmd);
 499        }
 500        if (close(async.out)) {
 501                err = error("read from external filter '%s' failed", cmd);
 502        }
 503        if (finish_async(&async)) {
 504                err = error("external filter '%s' failed", cmd);
 505        }
 506
 507        if (!err) {
 508                strbuf_swap(dst, &nbuf);
 509        }
 510        strbuf_release(&nbuf);
 511        return !err;
 512}
 513
 514#define CAP_CLEAN    (1u<<0)
 515#define CAP_SMUDGE   (1u<<1)
 516#define CAP_DELAY    (1u<<2)
 517
 518struct cmd2process {
 519        struct subprocess_entry subprocess; /* must be the first member! */
 520        unsigned int supported_capabilities;
 521};
 522
 523static int subprocess_map_initialized;
 524static struct hashmap subprocess_map;
 525
 526static int start_multi_file_filter_fn(struct subprocess_entry *subprocess)
 527{
 528        static int versions[] = {2, 0};
 529        static struct subprocess_capability capabilities[] = {
 530                { "clean",  CAP_CLEAN  },
 531                { "smudge", CAP_SMUDGE },
 532                { "delay",  CAP_DELAY  },
 533                { NULL, 0 }
 534        };
 535        struct cmd2process *entry = (struct cmd2process *)subprocess;
 536        return subprocess_handshake(subprocess, "git-filter", versions, NULL,
 537                                    capabilities,
 538                                    &entry->supported_capabilities);
 539}
 540
 541static void handle_filter_error(const struct strbuf *filter_status,
 542                                struct cmd2process *entry,
 543                                const unsigned int wanted_capability) {
 544        if (!strcmp(filter_status->buf, "error"))
 545                ; /* The filter signaled a problem with the file. */
 546        else if (!strcmp(filter_status->buf, "abort") && wanted_capability) {
 547                /*
 548                 * The filter signaled a permanent problem. Don't try to filter
 549                 * files with the same command for the lifetime of the current
 550                 * Git process.
 551                 */
 552                 entry->supported_capabilities &= ~wanted_capability;
 553        } else {
 554                /*
 555                 * Something went wrong with the protocol filter.
 556                 * Force shutdown and restart if another blob requires filtering.
 557                 */
 558                error("external filter '%s' failed", entry->subprocess.cmd);
 559                subprocess_stop(&subprocess_map, &entry->subprocess);
 560                free(entry);
 561        }
 562}
 563
 564static int apply_multi_file_filter(const char *path, const char *src, size_t len,
 565                                   int fd, struct strbuf *dst, const char *cmd,
 566                                   const unsigned int wanted_capability,
 567                                   struct delayed_checkout *dco)
 568{
 569        int err;
 570        int can_delay = 0;
 571        struct cmd2process *entry;
 572        struct child_process *process;
 573        struct strbuf nbuf = STRBUF_INIT;
 574        struct strbuf filter_status = STRBUF_INIT;
 575        const char *filter_type;
 576
 577        if (!subprocess_map_initialized) {
 578                subprocess_map_initialized = 1;
 579                hashmap_init(&subprocess_map, cmd2process_cmp, NULL, 0);
 580                entry = NULL;
 581        } else {
 582                entry = (struct cmd2process *)subprocess_find_entry(&subprocess_map, cmd);
 583        }
 584
 585        fflush(NULL);
 586
 587        if (!entry) {
 588                entry = xmalloc(sizeof(*entry));
 589                entry->supported_capabilities = 0;
 590
 591                if (subprocess_start(&subprocess_map, &entry->subprocess, cmd, start_multi_file_filter_fn)) {
 592                        free(entry);
 593                        return 0;
 594                }
 595        }
 596        process = &entry->subprocess.process;
 597
 598        if (!(entry->supported_capabilities & wanted_capability))
 599                return 0;
 600
 601        if (wanted_capability & CAP_CLEAN)
 602                filter_type = "clean";
 603        else if (wanted_capability & CAP_SMUDGE)
 604                filter_type = "smudge";
 605        else
 606                die("unexpected filter type");
 607
 608        sigchain_push(SIGPIPE, SIG_IGN);
 609
 610        assert(strlen(filter_type) < LARGE_PACKET_DATA_MAX - strlen("command=\n"));
 611        err = packet_write_fmt_gently(process->in, "command=%s\n", filter_type);
 612        if (err)
 613                goto done;
 614
 615        err = strlen(path) > LARGE_PACKET_DATA_MAX - strlen("pathname=\n");
 616        if (err) {
 617                error("path name too long for external filter");
 618                goto done;
 619        }
 620
 621        err = packet_write_fmt_gently(process->in, "pathname=%s\n", path);
 622        if (err)
 623                goto done;
 624
 625        if ((entry->supported_capabilities & CAP_DELAY) &&
 626            dco && dco->state == CE_CAN_DELAY) {
 627                can_delay = 1;
 628                err = packet_write_fmt_gently(process->in, "can-delay=1\n");
 629                if (err)
 630                        goto done;
 631        }
 632
 633        err = packet_flush_gently(process->in);
 634        if (err)
 635                goto done;
 636
 637        if (fd >= 0)
 638                err = write_packetized_from_fd(fd, process->in);
 639        else
 640                err = write_packetized_from_buf(src, len, process->in);
 641        if (err)
 642                goto done;
 643
 644        err = subprocess_read_status(process->out, &filter_status);
 645        if (err)
 646                goto done;
 647
 648        if (can_delay && !strcmp(filter_status.buf, "delayed")) {
 649                string_list_insert(&dco->filters, cmd);
 650                string_list_insert(&dco->paths, path);
 651        } else {
 652                /* The filter got the blob and wants to send us a response. */
 653                err = strcmp(filter_status.buf, "success");
 654                if (err)
 655                        goto done;
 656
 657                err = read_packetized_to_strbuf(process->out, &nbuf) < 0;
 658                if (err)
 659                        goto done;
 660
 661                err = subprocess_read_status(process->out, &filter_status);
 662                if (err)
 663                        goto done;
 664
 665                err = strcmp(filter_status.buf, "success");
 666        }
 667
 668done:
 669        sigchain_pop(SIGPIPE);
 670
 671        if (err)
 672                handle_filter_error(&filter_status, entry, wanted_capability);
 673        else
 674                strbuf_swap(dst, &nbuf);
 675        strbuf_release(&nbuf);
 676        return !err;
 677}
 678
 679
 680int async_query_available_blobs(const char *cmd, struct string_list *available_paths)
 681{
 682        int err;
 683        char *line;
 684        struct cmd2process *entry;
 685        struct child_process *process;
 686        struct strbuf filter_status = STRBUF_INIT;
 687
 688        assert(subprocess_map_initialized);
 689        entry = (struct cmd2process *)subprocess_find_entry(&subprocess_map, cmd);
 690        if (!entry) {
 691                error("external filter '%s' is not available anymore although "
 692                      "not all paths have been filtered", cmd);
 693                return 0;
 694        }
 695        process = &entry->subprocess.process;
 696        sigchain_push(SIGPIPE, SIG_IGN);
 697
 698        err = packet_write_fmt_gently(
 699                process->in, "command=list_available_blobs\n");
 700        if (err)
 701                goto done;
 702
 703        err = packet_flush_gently(process->in);
 704        if (err)
 705                goto done;
 706
 707        while ((line = packet_read_line(process->out, NULL))) {
 708                const char *path;
 709                if (skip_prefix(line, "pathname=", &path))
 710                        string_list_insert(available_paths, xstrdup(path));
 711                else
 712                        ; /* ignore unknown keys */
 713        }
 714
 715        err = subprocess_read_status(process->out, &filter_status);
 716        if (err)
 717                goto done;
 718
 719        err = strcmp(filter_status.buf, "success");
 720
 721done:
 722        sigchain_pop(SIGPIPE);
 723
 724        if (err)
 725                handle_filter_error(&filter_status, entry, 0);
 726        return !err;
 727}
 728
 729static struct convert_driver {
 730        const char *name;
 731        struct convert_driver *next;
 732        const char *smudge;
 733        const char *clean;
 734        const char *process;
 735        int required;
 736} *user_convert, **user_convert_tail;
 737
 738static int apply_filter(const char *path, const char *src, size_t len,
 739                        int fd, struct strbuf *dst, struct convert_driver *drv,
 740                        const unsigned int wanted_capability,
 741                        struct delayed_checkout *dco)
 742{
 743        const char *cmd = NULL;
 744
 745        if (!drv)
 746                return 0;
 747
 748        if (!dst)
 749                return 1;
 750
 751        if ((wanted_capability & CAP_CLEAN) && !drv->process && drv->clean)
 752                cmd = drv->clean;
 753        else if ((wanted_capability & CAP_SMUDGE) && !drv->process && drv->smudge)
 754                cmd = drv->smudge;
 755
 756        if (cmd && *cmd)
 757                return apply_single_file_filter(path, src, len, fd, dst, cmd);
 758        else if (drv->process && *drv->process)
 759                return apply_multi_file_filter(path, src, len, fd, dst,
 760                        drv->process, wanted_capability, dco);
 761
 762        return 0;
 763}
 764
 765static int read_convert_config(const char *var, const char *value, void *cb)
 766{
 767        const char *key, *name;
 768        int namelen;
 769        struct convert_driver *drv;
 770
 771        /*
 772         * External conversion drivers are configured using
 773         * "filter.<name>.variable".
 774         */
 775        if (parse_config_key(var, "filter", &name, &namelen, &key) < 0 || !name)
 776                return 0;
 777        for (drv = user_convert; drv; drv = drv->next)
 778                if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 779                        break;
 780        if (!drv) {
 781                drv = xcalloc(1, sizeof(struct convert_driver));
 782                drv->name = xmemdupz(name, namelen);
 783                *user_convert_tail = drv;
 784                user_convert_tail = &(drv->next);
 785        }
 786
 787        /*
 788         * filter.<name>.smudge and filter.<name>.clean specifies
 789         * the command line:
 790         *
 791         *      command-line
 792         *
 793         * The command-line will not be interpolated in any way.
 794         */
 795
 796        if (!strcmp("smudge", key))
 797                return git_config_string(&drv->smudge, var, value);
 798
 799        if (!strcmp("clean", key))
 800                return git_config_string(&drv->clean, var, value);
 801
 802        if (!strcmp("process", key))
 803                return git_config_string(&drv->process, var, value);
 804
 805        if (!strcmp("required", key)) {
 806                drv->required = git_config_bool(var, value);
 807                return 0;
 808        }
 809
 810        return 0;
 811}
 812
 813static int count_ident(const char *cp, unsigned long size)
 814{
 815        /*
 816         * "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
 817         */
 818        int cnt = 0;
 819        char ch;
 820
 821        while (size) {
 822                ch = *cp++;
 823                size--;
 824                if (ch != '$')
 825                        continue;
 826                if (size < 3)
 827                        break;
 828                if (memcmp("Id", cp, 2))
 829                        continue;
 830                ch = cp[2];
 831                cp += 3;
 832                size -= 3;
 833                if (ch == '$')
 834                        cnt++; /* $Id$ */
 835                if (ch != ':')
 836                        continue;
 837
 838                /*
 839                 * "$Id: ... "; scan up to the closing dollar sign and discard.
 840                 */
 841                while (size) {
 842                        ch = *cp++;
 843                        size--;
 844                        if (ch == '$') {
 845                                cnt++;
 846                                break;
 847                        }
 848                        if (ch == '\n')
 849                                break;
 850                }
 851        }
 852        return cnt;
 853}
 854
 855static int ident_to_git(const char *path, const char *src, size_t len,
 856                        struct strbuf *buf, int ident)
 857{
 858        char *dst, *dollar;
 859
 860        if (!ident || (src && !count_ident(src, len)))
 861                return 0;
 862
 863        if (!buf)
 864                return 1;
 865
 866        /* only grow if not in place */
 867        if (strbuf_avail(buf) + buf->len < len)
 868                strbuf_grow(buf, len - buf->len);
 869        dst = buf->buf;
 870        for (;;) {
 871                dollar = memchr(src, '$', len);
 872                if (!dollar)
 873                        break;
 874                memmove(dst, src, dollar + 1 - src);
 875                dst += dollar + 1 - src;
 876                len -= dollar + 1 - src;
 877                src  = dollar + 1;
 878
 879                if (len > 3 && !memcmp(src, "Id:", 3)) {
 880                        dollar = memchr(src + 3, '$', len - 3);
 881                        if (!dollar)
 882                                break;
 883                        if (memchr(src + 3, '\n', dollar - src - 3)) {
 884                                /* Line break before the next dollar. */
 885                                continue;
 886                        }
 887
 888                        memcpy(dst, "Id$", 3);
 889                        dst += 3;
 890                        len -= dollar + 1 - src;
 891                        src  = dollar + 1;
 892                }
 893        }
 894        memmove(dst, src, len);
 895        strbuf_setlen(buf, dst + len - buf->buf);
 896        return 1;
 897}
 898
 899static int ident_to_worktree(const char *path, const char *src, size_t len,
 900                             struct strbuf *buf, int ident)
 901{
 902        struct object_id oid;
 903        char *to_free = NULL, *dollar, *spc;
 904        int cnt;
 905
 906        if (!ident)
 907                return 0;
 908
 909        cnt = count_ident(src, len);
 910        if (!cnt)
 911                return 0;
 912
 913        /* are we "faking" in place editing ? */
 914        if (src == buf->buf)
 915                to_free = strbuf_detach(buf, NULL);
 916        hash_object_file(src, len, "blob", &oid);
 917
 918        strbuf_grow(buf, len + cnt * (the_hash_algo->hexsz + 3));
 919        for (;;) {
 920                /* step 1: run to the next '$' */
 921                dollar = memchr(src, '$', len);
 922                if (!dollar)
 923                        break;
 924                strbuf_add(buf, src, dollar + 1 - src);
 925                len -= dollar + 1 - src;
 926                src  = dollar + 1;
 927
 928                /* step 2: does it looks like a bit like Id:xxx$ or Id$ ? */
 929                if (len < 3 || memcmp("Id", src, 2))
 930                        continue;
 931
 932                /* step 3: skip over Id$ or Id:xxxxx$ */
 933                if (src[2] == '$') {
 934                        src += 3;
 935                        len -= 3;
 936                } else if (src[2] == ':') {
 937                        /*
 938                         * It's possible that an expanded Id has crept its way into the
 939                         * repository, we cope with that by stripping the expansion out.
 940                         * This is probably not a good idea, since it will cause changes
 941                         * on checkout, which won't go away by stash, but let's keep it
 942                         * for git-style ids.
 943                         */
 944                        dollar = memchr(src + 3, '$', len - 3);
 945                        if (!dollar) {
 946                                /* incomplete keyword, no more '$', so just quit the loop */
 947                                break;
 948                        }
 949
 950                        if (memchr(src + 3, '\n', dollar - src - 3)) {
 951                                /* Line break before the next dollar. */
 952                                continue;
 953                        }
 954
 955                        spc = memchr(src + 4, ' ', dollar - src - 4);
 956                        if (spc && spc < dollar-1) {
 957                                /* There are spaces in unexpected places.
 958                                 * This is probably an id from some other
 959                                 * versioning system. Keep it for now.
 960                                 */
 961                                continue;
 962                        }
 963
 964                        len -= dollar + 1 - src;
 965                        src  = dollar + 1;
 966                } else {
 967                        /* it wasn't a "Id$" or "Id:xxxx$" */
 968                        continue;
 969                }
 970
 971                /* step 4: substitute */
 972                strbuf_addstr(buf, "Id: ");
 973                strbuf_addstr(buf, oid_to_hex(&oid));
 974                strbuf_addstr(buf, " $");
 975        }
 976        strbuf_add(buf, src, len);
 977
 978        free(to_free);
 979        return 1;
 980}
 981
 982static enum crlf_action git_path_check_crlf(struct attr_check_item *check)
 983{
 984        const char *value = check->value;
 985
 986        if (ATTR_TRUE(value))
 987                return CRLF_TEXT;
 988        else if (ATTR_FALSE(value))
 989                return CRLF_BINARY;
 990        else if (ATTR_UNSET(value))
 991                ;
 992        else if (!strcmp(value, "input"))
 993                return CRLF_TEXT_INPUT;
 994        else if (!strcmp(value, "auto"))
 995                return CRLF_AUTO;
 996        return CRLF_UNDEFINED;
 997}
 998
 999static enum eol git_path_check_eol(struct attr_check_item *check)
1000{
1001        const char *value = check->value;
1002
1003        if (ATTR_UNSET(value))
1004                ;
1005        else if (!strcmp(value, "lf"))
1006                return EOL_LF;
1007        else if (!strcmp(value, "crlf"))
1008                return EOL_CRLF;
1009        return EOL_UNSET;
1010}
1011
1012static struct convert_driver *git_path_check_convert(struct attr_check_item *check)
1013{
1014        const char *value = check->value;
1015        struct convert_driver *drv;
1016
1017        if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
1018                return NULL;
1019        for (drv = user_convert; drv; drv = drv->next)
1020                if (!strcmp(value, drv->name))
1021                        return drv;
1022        return NULL;
1023}
1024
1025static int git_path_check_ident(struct attr_check_item *check)
1026{
1027        const char *value = check->value;
1028
1029        return !!ATTR_TRUE(value);
1030}
1031
1032struct conv_attrs {
1033        struct convert_driver *drv;
1034        enum crlf_action attr_action; /* What attr says */
1035        enum crlf_action crlf_action; /* When no attr is set, use core.autocrlf */
1036        int ident;
1037};
1038
1039static void convert_attrs(struct conv_attrs *ca, const char *path)
1040{
1041        static struct attr_check *check;
1042
1043        if (!check) {
1044                check = attr_check_initl("crlf", "ident", "filter",
1045                                         "eol", "text", NULL);
1046                user_convert_tail = &user_convert;
1047                git_config(read_convert_config, NULL);
1048        }
1049
1050        if (!git_check_attr(path, check)) {
1051                struct attr_check_item *ccheck = check->items;
1052                ca->crlf_action = git_path_check_crlf(ccheck + 4);
1053                if (ca->crlf_action == CRLF_UNDEFINED)
1054                        ca->crlf_action = git_path_check_crlf(ccheck + 0);
1055                ca->ident = git_path_check_ident(ccheck + 1);
1056                ca->drv = git_path_check_convert(ccheck + 2);
1057                if (ca->crlf_action != CRLF_BINARY) {
1058                        enum eol eol_attr = git_path_check_eol(ccheck + 3);
1059                        if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_LF)
1060                                ca->crlf_action = CRLF_AUTO_INPUT;
1061                        else if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_CRLF)
1062                                ca->crlf_action = CRLF_AUTO_CRLF;
1063                        else if (eol_attr == EOL_LF)
1064                                ca->crlf_action = CRLF_TEXT_INPUT;
1065                        else if (eol_attr == EOL_CRLF)
1066                                ca->crlf_action = CRLF_TEXT_CRLF;
1067                }
1068        } else {
1069                ca->drv = NULL;
1070                ca->crlf_action = CRLF_UNDEFINED;
1071                ca->ident = 0;
1072        }
1073
1074        /* Save attr and make a decision for action */
1075        ca->attr_action = ca->crlf_action;
1076        if (ca->crlf_action == CRLF_TEXT)
1077                ca->crlf_action = text_eol_is_crlf() ? CRLF_TEXT_CRLF : CRLF_TEXT_INPUT;
1078        if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_FALSE)
1079                ca->crlf_action = CRLF_BINARY;
1080        if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_TRUE)
1081                ca->crlf_action = CRLF_AUTO_CRLF;
1082        if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_INPUT)
1083                ca->crlf_action = CRLF_AUTO_INPUT;
1084}
1085
1086int would_convert_to_git_filter_fd(const char *path)
1087{
1088        struct conv_attrs ca;
1089
1090        convert_attrs(&ca, path);
1091        if (!ca.drv)
1092                return 0;
1093
1094        /*
1095         * Apply a filter to an fd only if the filter is required to succeed.
1096         * We must die if the filter fails, because the original data before
1097         * filtering is not available.
1098         */
1099        if (!ca.drv->required)
1100                return 0;
1101
1102        return apply_filter(path, NULL, 0, -1, NULL, ca.drv, CAP_CLEAN, NULL);
1103}
1104
1105const char *get_convert_attr_ascii(const char *path)
1106{
1107        struct conv_attrs ca;
1108
1109        convert_attrs(&ca, path);
1110        switch (ca.attr_action) {
1111        case CRLF_UNDEFINED:
1112                return "";
1113        case CRLF_BINARY:
1114                return "-text";
1115        case CRLF_TEXT:
1116                return "text";
1117        case CRLF_TEXT_INPUT:
1118                return "text eol=lf";
1119        case CRLF_TEXT_CRLF:
1120                return "text eol=crlf";
1121        case CRLF_AUTO:
1122                return "text=auto";
1123        case CRLF_AUTO_CRLF:
1124                return "text=auto eol=crlf";
1125        case CRLF_AUTO_INPUT:
1126                return "text=auto eol=lf";
1127        }
1128        return "";
1129}
1130
1131int convert_to_git(const struct index_state *istate,
1132                   const char *path, const char *src, size_t len,
1133                   struct strbuf *dst, int conv_flags)
1134{
1135        int ret = 0;
1136        struct conv_attrs ca;
1137
1138        convert_attrs(&ca, path);
1139
1140        ret |= apply_filter(path, src, len, -1, dst, ca.drv, CAP_CLEAN, NULL);
1141        if (!ret && ca.drv && ca.drv->required)
1142                die("%s: clean filter '%s' failed", path, ca.drv->name);
1143
1144        if (ret && dst) {
1145                src = dst->buf;
1146                len = dst->len;
1147        }
1148        if (!(conv_flags & CONV_EOL_KEEP_CRLF)) {
1149                ret |= crlf_to_git(istate, path, src, len, dst, ca.crlf_action, conv_flags);
1150                if (ret && dst) {
1151                        src = dst->buf;
1152                        len = dst->len;
1153                }
1154        }
1155        return ret | ident_to_git(path, src, len, dst, ca.ident);
1156}
1157
1158void convert_to_git_filter_fd(const struct index_state *istate,
1159                              const char *path, int fd, struct strbuf *dst,
1160                              int conv_flags)
1161{
1162        struct conv_attrs ca;
1163        convert_attrs(&ca, path);
1164
1165        assert(ca.drv);
1166        assert(ca.drv->clean || ca.drv->process);
1167
1168        if (!apply_filter(path, NULL, 0, fd, dst, ca.drv, CAP_CLEAN, NULL))
1169                die("%s: clean filter '%s' failed", path, ca.drv->name);
1170
1171        crlf_to_git(istate, path, dst->buf, dst->len, dst, ca.crlf_action, conv_flags);
1172        ident_to_git(path, dst->buf, dst->len, dst, ca.ident);
1173}
1174
1175static int convert_to_working_tree_internal(const char *path, const char *src,
1176                                            size_t len, struct strbuf *dst,
1177                                            int normalizing, struct delayed_checkout *dco)
1178{
1179        int ret = 0, ret_filter = 0;
1180        struct conv_attrs ca;
1181
1182        convert_attrs(&ca, path);
1183
1184        ret |= ident_to_worktree(path, src, len, dst, ca.ident);
1185        if (ret) {
1186                src = dst->buf;
1187                len = dst->len;
1188        }
1189        /*
1190         * CRLF conversion can be skipped if normalizing, unless there
1191         * is a smudge or process filter (even if the process filter doesn't
1192         * support smudge).  The filters might expect CRLFs.
1193         */
1194        if ((ca.drv && (ca.drv->smudge || ca.drv->process)) || !normalizing) {
1195                ret |= crlf_to_worktree(path, src, len, dst, ca.crlf_action);
1196                if (ret) {
1197                        src = dst->buf;
1198                        len = dst->len;
1199                }
1200        }
1201
1202        ret_filter = apply_filter(
1203                path, src, len, -1, dst, ca.drv, CAP_SMUDGE, dco);
1204        if (!ret_filter && ca.drv && ca.drv->required)
1205                die("%s: smudge filter %s failed", path, ca.drv->name);
1206
1207        return ret | ret_filter;
1208}
1209
1210int async_convert_to_working_tree(const char *path, const char *src,
1211                                  size_t len, struct strbuf *dst,
1212                                  void *dco)
1213{
1214        return convert_to_working_tree_internal(path, src, len, dst, 0, dco);
1215}
1216
1217int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst)
1218{
1219        return convert_to_working_tree_internal(path, src, len, dst, 0, NULL);
1220}
1221
1222int renormalize_buffer(const struct index_state *istate, const char *path,
1223                       const char *src, size_t len, struct strbuf *dst)
1224{
1225        int ret = convert_to_working_tree_internal(path, src, len, dst, 1, NULL);
1226        if (ret) {
1227                src = dst->buf;
1228                len = dst->len;
1229        }
1230        return ret | convert_to_git(istate, path, src, len, dst, CONV_EOL_RENORMALIZE);
1231}
1232
1233/*****************************************************************
1234 *
1235 * Streaming conversion support
1236 *
1237 *****************************************************************/
1238
1239typedef int (*filter_fn)(struct stream_filter *,
1240                         const char *input, size_t *isize_p,
1241                         char *output, size_t *osize_p);
1242typedef void (*free_fn)(struct stream_filter *);
1243
1244struct stream_filter_vtbl {
1245        filter_fn filter;
1246        free_fn free;
1247};
1248
1249struct stream_filter {
1250        struct stream_filter_vtbl *vtbl;
1251};
1252
1253static int null_filter_fn(struct stream_filter *filter,
1254                          const char *input, size_t *isize_p,
1255                          char *output, size_t *osize_p)
1256{
1257        size_t count;
1258
1259        if (!input)
1260                return 0; /* we do not keep any states */
1261        count = *isize_p;
1262        if (*osize_p < count)
1263                count = *osize_p;
1264        if (count) {
1265                memmove(output, input, count);
1266                *isize_p -= count;
1267                *osize_p -= count;
1268        }
1269        return 0;
1270}
1271
1272static void null_free_fn(struct stream_filter *filter)
1273{
1274        ; /* nothing -- null instances are shared */
1275}
1276
1277static struct stream_filter_vtbl null_vtbl = {
1278        null_filter_fn,
1279        null_free_fn,
1280};
1281
1282static struct stream_filter null_filter_singleton = {
1283        &null_vtbl,
1284};
1285
1286int is_null_stream_filter(struct stream_filter *filter)
1287{
1288        return filter == &null_filter_singleton;
1289}
1290
1291
1292/*
1293 * LF-to-CRLF filter
1294 */
1295
1296struct lf_to_crlf_filter {
1297        struct stream_filter filter;
1298        unsigned has_held:1;
1299        char held;
1300};
1301
1302static int lf_to_crlf_filter_fn(struct stream_filter *filter,
1303                                const char *input, size_t *isize_p,
1304                                char *output, size_t *osize_p)
1305{
1306        size_t count, o = 0;
1307        struct lf_to_crlf_filter *lf_to_crlf = (struct lf_to_crlf_filter *)filter;
1308
1309        /*
1310         * We may be holding onto the CR to see if it is followed by a
1311         * LF, in which case we would need to go to the main loop.
1312         * Otherwise, just emit it to the output stream.
1313         */
1314        if (lf_to_crlf->has_held && (lf_to_crlf->held != '\r' || !input)) {
1315                output[o++] = lf_to_crlf->held;
1316                lf_to_crlf->has_held = 0;
1317        }
1318
1319        /* We are told to drain */
1320        if (!input) {
1321                *osize_p -= o;
1322                return 0;
1323        }
1324
1325        count = *isize_p;
1326        if (count || lf_to_crlf->has_held) {
1327                size_t i;
1328                int was_cr = 0;
1329
1330                if (lf_to_crlf->has_held) {
1331                        was_cr = 1;
1332                        lf_to_crlf->has_held = 0;
1333                }
1334
1335                for (i = 0; o < *osize_p && i < count; i++) {
1336                        char ch = input[i];
1337
1338                        if (ch == '\n') {
1339                                output[o++] = '\r';
1340                        } else if (was_cr) {
1341                                /*
1342                                 * Previous round saw CR and it is not followed
1343                                 * by a LF; emit the CR before processing the
1344                                 * current character.
1345                                 */
1346                                output[o++] = '\r';
1347                        }
1348
1349                        /*
1350                         * We may have consumed the last output slot,
1351                         * in which case we need to break out of this
1352                         * loop; hold the current character before
1353                         * returning.
1354                         */
1355                        if (*osize_p <= o) {
1356                                lf_to_crlf->has_held = 1;
1357                                lf_to_crlf->held = ch;
1358                                continue; /* break but increment i */
1359                        }
1360
1361                        if (ch == '\r') {
1362                                was_cr = 1;
1363                                continue;
1364                        }
1365
1366                        was_cr = 0;
1367                        output[o++] = ch;
1368                }
1369
1370                *osize_p -= o;
1371                *isize_p -= i;
1372
1373                if (!lf_to_crlf->has_held && was_cr) {
1374                        lf_to_crlf->has_held = 1;
1375                        lf_to_crlf->held = '\r';
1376                }
1377        }
1378        return 0;
1379}
1380
1381static void lf_to_crlf_free_fn(struct stream_filter *filter)
1382{
1383        free(filter);
1384}
1385
1386static struct stream_filter_vtbl lf_to_crlf_vtbl = {
1387        lf_to_crlf_filter_fn,
1388        lf_to_crlf_free_fn,
1389};
1390
1391static struct stream_filter *lf_to_crlf_filter(void)
1392{
1393        struct lf_to_crlf_filter *lf_to_crlf = xcalloc(1, sizeof(*lf_to_crlf));
1394
1395        lf_to_crlf->filter.vtbl = &lf_to_crlf_vtbl;
1396        return (struct stream_filter *)lf_to_crlf;
1397}
1398
1399/*
1400 * Cascade filter
1401 */
1402#define FILTER_BUFFER 1024
1403struct cascade_filter {
1404        struct stream_filter filter;
1405        struct stream_filter *one;
1406        struct stream_filter *two;
1407        char buf[FILTER_BUFFER];
1408        int end, ptr;
1409};
1410
1411static int cascade_filter_fn(struct stream_filter *filter,
1412                             const char *input, size_t *isize_p,
1413                             char *output, size_t *osize_p)
1414{
1415        struct cascade_filter *cas = (struct cascade_filter *) filter;
1416        size_t filled = 0;
1417        size_t sz = *osize_p;
1418        size_t to_feed, remaining;
1419
1420        /*
1421         * input -- (one) --> buf -- (two) --> output
1422         */
1423        while (filled < sz) {
1424                remaining = sz - filled;
1425
1426                /* do we already have something to feed two with? */
1427                if (cas->ptr < cas->end) {
1428                        to_feed = cas->end - cas->ptr;
1429                        if (stream_filter(cas->two,
1430                                          cas->buf + cas->ptr, &to_feed,
1431                                          output + filled, &remaining))
1432                                return -1;
1433                        cas->ptr += (cas->end - cas->ptr) - to_feed;
1434                        filled = sz - remaining;
1435                        continue;
1436                }
1437
1438                /* feed one from upstream and have it emit into our buffer */
1439                to_feed = input ? *isize_p : 0;
1440                if (input && !to_feed)
1441                        break;
1442                remaining = sizeof(cas->buf);
1443                if (stream_filter(cas->one,
1444                                  input, &to_feed,
1445                                  cas->buf, &remaining))
1446                        return -1;
1447                cas->end = sizeof(cas->buf) - remaining;
1448                cas->ptr = 0;
1449                if (input) {
1450                        size_t fed = *isize_p - to_feed;
1451                        *isize_p -= fed;
1452                        input += fed;
1453                }
1454
1455                /* do we know that we drained one completely? */
1456                if (input || cas->end)
1457                        continue;
1458
1459                /* tell two to drain; we have nothing more to give it */
1460                to_feed = 0;
1461                remaining = sz - filled;
1462                if (stream_filter(cas->two,
1463                                  NULL, &to_feed,
1464                                  output + filled, &remaining))
1465                        return -1;
1466                if (remaining == (sz - filled))
1467                        break; /* completely drained two */
1468                filled = sz - remaining;
1469        }
1470        *osize_p -= filled;
1471        return 0;
1472}
1473
1474static void cascade_free_fn(struct stream_filter *filter)
1475{
1476        struct cascade_filter *cas = (struct cascade_filter *)filter;
1477        free_stream_filter(cas->one);
1478        free_stream_filter(cas->two);
1479        free(filter);
1480}
1481
1482static struct stream_filter_vtbl cascade_vtbl = {
1483        cascade_filter_fn,
1484        cascade_free_fn,
1485};
1486
1487static struct stream_filter *cascade_filter(struct stream_filter *one,
1488                                            struct stream_filter *two)
1489{
1490        struct cascade_filter *cascade;
1491
1492        if (!one || is_null_stream_filter(one))
1493                return two;
1494        if (!two || is_null_stream_filter(two))
1495                return one;
1496
1497        cascade = xmalloc(sizeof(*cascade));
1498        cascade->one = one;
1499        cascade->two = two;
1500        cascade->end = cascade->ptr = 0;
1501        cascade->filter.vtbl = &cascade_vtbl;
1502        return (struct stream_filter *)cascade;
1503}
1504
1505/*
1506 * ident filter
1507 */
1508#define IDENT_DRAINING (-1)
1509#define IDENT_SKIPPING (-2)
1510struct ident_filter {
1511        struct stream_filter filter;
1512        struct strbuf left;
1513        int state;
1514        char ident[GIT_MAX_HEXSZ + 5]; /* ": x40 $" */
1515};
1516
1517static int is_foreign_ident(const char *str)
1518{
1519        int i;
1520
1521        if (!skip_prefix(str, "$Id: ", &str))
1522                return 0;
1523        for (i = 0; str[i]; i++) {
1524                if (isspace(str[i]) && str[i+1] != '$')
1525                        return 1;
1526        }
1527        return 0;
1528}
1529
1530static void ident_drain(struct ident_filter *ident, char **output_p, size_t *osize_p)
1531{
1532        size_t to_drain = ident->left.len;
1533
1534        if (*osize_p < to_drain)
1535                to_drain = *osize_p;
1536        if (to_drain) {
1537                memcpy(*output_p, ident->left.buf, to_drain);
1538                strbuf_remove(&ident->left, 0, to_drain);
1539                *output_p += to_drain;
1540                *osize_p -= to_drain;
1541        }
1542        if (!ident->left.len)
1543                ident->state = 0;
1544}
1545
1546static int ident_filter_fn(struct stream_filter *filter,
1547                           const char *input, size_t *isize_p,
1548                           char *output, size_t *osize_p)
1549{
1550        struct ident_filter *ident = (struct ident_filter *)filter;
1551        static const char head[] = "$Id";
1552
1553        if (!input) {
1554                /* drain upon eof */
1555                switch (ident->state) {
1556                default:
1557                        strbuf_add(&ident->left, head, ident->state);
1558                        /* fallthrough */
1559                case IDENT_SKIPPING:
1560                        /* fallthrough */
1561                case IDENT_DRAINING:
1562                        ident_drain(ident, &output, osize_p);
1563                }
1564                return 0;
1565        }
1566
1567        while (*isize_p || (ident->state == IDENT_DRAINING)) {
1568                int ch;
1569
1570                if (ident->state == IDENT_DRAINING) {
1571                        ident_drain(ident, &output, osize_p);
1572                        if (!*osize_p)
1573                                break;
1574                        continue;
1575                }
1576
1577                ch = *(input++);
1578                (*isize_p)--;
1579
1580                if (ident->state == IDENT_SKIPPING) {
1581                        /*
1582                         * Skipping until '$' or LF, but keeping them
1583                         * in case it is a foreign ident.
1584                         */
1585                        strbuf_addch(&ident->left, ch);
1586                        if (ch != '\n' && ch != '$')
1587                                continue;
1588                        if (ch == '$' && !is_foreign_ident(ident->left.buf)) {
1589                                strbuf_setlen(&ident->left, sizeof(head) - 1);
1590                                strbuf_addstr(&ident->left, ident->ident);
1591                        }
1592                        ident->state = IDENT_DRAINING;
1593                        continue;
1594                }
1595
1596                if (ident->state < sizeof(head) &&
1597                    head[ident->state] == ch) {
1598                        ident->state++;
1599                        continue;
1600                }
1601
1602                if (ident->state)
1603                        strbuf_add(&ident->left, head, ident->state);
1604                if (ident->state == sizeof(head) - 1) {
1605                        if (ch != ':' && ch != '$') {
1606                                strbuf_addch(&ident->left, ch);
1607                                ident->state = 0;
1608                                continue;
1609                        }
1610
1611                        if (ch == ':') {
1612                                strbuf_addch(&ident->left, ch);
1613                                ident->state = IDENT_SKIPPING;
1614                        } else {
1615                                strbuf_addstr(&ident->left, ident->ident);
1616                                ident->state = IDENT_DRAINING;
1617                        }
1618                        continue;
1619                }
1620
1621                strbuf_addch(&ident->left, ch);
1622                ident->state = IDENT_DRAINING;
1623        }
1624        return 0;
1625}
1626
1627static void ident_free_fn(struct stream_filter *filter)
1628{
1629        struct ident_filter *ident = (struct ident_filter *)filter;
1630        strbuf_release(&ident->left);
1631        free(filter);
1632}
1633
1634static struct stream_filter_vtbl ident_vtbl = {
1635        ident_filter_fn,
1636        ident_free_fn,
1637};
1638
1639static struct stream_filter *ident_filter(const struct object_id *oid)
1640{
1641        struct ident_filter *ident = xmalloc(sizeof(*ident));
1642
1643        xsnprintf(ident->ident, sizeof(ident->ident),
1644                  ": %s $", oid_to_hex(oid));
1645        strbuf_init(&ident->left, 0);
1646        ident->filter.vtbl = &ident_vtbl;
1647        ident->state = 0;
1648        return (struct stream_filter *)ident;
1649}
1650
1651/*
1652 * Return an appropriately constructed filter for the path, or NULL if
1653 * the contents cannot be filtered without reading the whole thing
1654 * in-core.
1655 *
1656 * Note that you would be crazy to set CRLF, smuge/clean or ident to a
1657 * large binary blob you would want us not to slurp into the memory!
1658 */
1659struct stream_filter *get_stream_filter(const char *path, const struct object_id *oid)
1660{
1661        struct conv_attrs ca;
1662        struct stream_filter *filter = NULL;
1663
1664        convert_attrs(&ca, path);
1665        if (ca.drv && (ca.drv->process || ca.drv->smudge || ca.drv->clean))
1666                return NULL;
1667
1668        if (ca.crlf_action == CRLF_AUTO || ca.crlf_action == CRLF_AUTO_CRLF)
1669                return NULL;
1670
1671        if (ca.ident)
1672                filter = ident_filter(oid);
1673
1674        if (output_eol(ca.crlf_action) == EOL_CRLF)
1675                filter = cascade_filter(filter, lf_to_crlf_filter());
1676        else
1677                filter = cascade_filter(filter, &null_filter_singleton);
1678
1679        return filter;
1680}
1681
1682void free_stream_filter(struct stream_filter *filter)
1683{
1684        filter->vtbl->free(filter);
1685}
1686
1687int stream_filter(struct stream_filter *filter,
1688                  const char *input, size_t *isize_p,
1689                  char *output, size_t *osize_p)
1690{
1691        return filter->vtbl->filter(filter, input, isize_p, output, osize_p);
1692}