Andrew's git / gitweb.git / convert.c
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convert.con commit Reduce the number of connects when fetching (ba22785)
   1#include "cache.h"
   2#include "attr.h"
   3#include "run-command.h"
   4
   5/*
   6 * convert.c - convert a file when checking it out and checking it in.
   7 *
   8 * This should use the pathname to decide on whether it wants to do some
   9 * more interesting conversions (automatic gzip/unzip, general format
  10 * conversions etc etc), but by default it just does automatic CRLF<->LF
  11 * translation when the "auto_crlf" option is set.
  12 */
  13
  14#define CRLF_GUESS      (-1)
  15#define CRLF_BINARY     0
  16#define CRLF_TEXT       1
  17#define CRLF_INPUT      2
  18
  19struct text_stat {
  20        /* NUL, CR, LF and CRLF counts */
  21        unsigned nul, cr, lf, crlf;
  22
  23        /* These are just approximations! */
  24        unsigned printable, nonprintable;
  25};
  26
  27static void gather_stats(const char *buf, unsigned long size, struct text_stat *stats)
  28{
  29        unsigned long i;
  30
  31        memset(stats, 0, sizeof(*stats));
  32
  33        for (i = 0; i < size; i++) {
  34                unsigned char c = buf[i];
  35                if (c == '\r') {
  36                        stats->cr++;
  37                        if (i+1 < size && buf[i+1] == '\n')
  38                                stats->crlf++;
  39                        continue;
  40                }
  41                if (c == '\n') {
  42                        stats->lf++;
  43                        continue;
  44                }
  45                if (c == 127)
  46                        /* DEL */
  47                        stats->nonprintable++;
  48                else if (c < 32) {
  49                        switch (c) {
  50                                /* BS, HT, ESC and FF */
  51                        case '\b': case '\t': case '\033': case '\014':
  52                                stats->printable++;
  53                                break;
  54                        case 0:
  55                                stats->nul++;
  56                                /* fall through */
  57                        default:
  58                                stats->nonprintable++;
  59                        }
  60                }
  61                else
  62                        stats->printable++;
  63        }
  64}
  65
  66/*
  67 * The same heuristics as diff.c::mmfile_is_binary()
  68 */
  69static int is_binary(unsigned long size, struct text_stat *stats)
  70{
  71
  72        if (stats->nul)
  73                return 1;
  74        if ((stats->printable >> 7) < stats->nonprintable)
  75                return 1;
  76        /*
  77         * Other heuristics? Average line length might be relevant,
  78         * as might LF vs CR vs CRLF counts..
  79         *
  80         * NOTE! It might be normal to have a low ratio of CRLF to LF
  81         * (somebody starts with a LF-only file and edits it with an editor
  82         * that adds CRLF only to lines that are added..). But do  we
  83         * want to support CR-only? Probably not.
  84         */
  85        return 0;
  86}
  87
  88static int crlf_to_git(const char *path, const char *src, size_t len,
  89                       struct strbuf *buf, int action)
  90{
  91        struct text_stat stats;
  92        char *dst;
  93
  94        if ((action == CRLF_BINARY) || !auto_crlf || !len)
  95                return 0;
  96
  97        gather_stats(src, len, &stats);
  98        /* No CR? Nothing to convert, regardless. */
  99        if (!stats.cr)
 100                return 0;
 101
 102        if (action == CRLF_GUESS) {
 103                /*
 104                 * We're currently not going to even try to convert stuff
 105                 * that has bare CR characters. Does anybody do that crazy
 106                 * stuff?
 107                 */
 108                if (stats.cr != stats.crlf)
 109                        return 0;
 110
 111                /*
 112                 * And add some heuristics for binary vs text, of course...
 113                 */
 114                if (is_binary(len, &stats))
 115                        return 0;
 116        }
 117
 118        /* only grow if not in place */
 119        if (strbuf_avail(buf) + buf->len < len)
 120                strbuf_grow(buf, len - buf->len);
 121        dst = buf->buf;
 122        if (action == CRLF_GUESS) {
 123                /*
 124                 * If we guessed, we already know we rejected a file with
 125                 * lone CR, and we can strip a CR without looking at what
 126                 * follow it.
 127                 */
 128                do {
 129                        unsigned char c = *src++;
 130                        if (c != '\r')
 131                                *dst++ = c;
 132                } while (--len);
 133        } else {
 134                do {
 135                        unsigned char c = *src++;
 136                        if (! (c == '\r' && (1 < len && *src == '\n')))
 137                                *dst++ = c;
 138                } while (--len);
 139        }
 140        strbuf_setlen(buf, dst - buf->buf);
 141        return 1;
 142}
 143
 144static int crlf_to_worktree(const char *path, const char *src, size_t len,
 145                            struct strbuf *buf, int action)
 146{
 147        char *to_free = NULL;
 148        struct text_stat stats;
 149
 150        if ((action == CRLF_BINARY) || (action == CRLF_INPUT) ||
 151            auto_crlf <= 0)
 152                return 0;
 153
 154        if (!len)
 155                return 0;
 156
 157        gather_stats(src, len, &stats);
 158
 159        /* No LF? Nothing to convert, regardless. */
 160        if (!stats.lf)
 161                return 0;
 162
 163        /* Was it already in CRLF format? */
 164        if (stats.lf == stats.crlf)
 165                return 0;
 166
 167        if (action == CRLF_GUESS) {
 168                /* If we have any bare CR characters, we're not going to touch it */
 169                if (stats.cr != stats.crlf)
 170                        return 0;
 171
 172                if (is_binary(len, &stats))
 173                        return 0;
 174        }
 175
 176        /* are we "faking" in place editing ? */
 177        if (src == buf->buf)
 178                to_free = strbuf_detach(buf, NULL);
 179
 180        strbuf_grow(buf, len + stats.lf - stats.crlf);
 181        for (;;) {
 182                const char *nl = memchr(src, '\n', len);
 183                if (!nl)
 184                        break;
 185                if (nl > src && nl[-1] == '\r') {
 186                        strbuf_add(buf, src, nl + 1 - src);
 187                } else {
 188                        strbuf_add(buf, src, nl - src);
 189                        strbuf_addstr(buf, "\r\n");
 190                }
 191                len -= nl + 1 - src;
 192                src  = nl + 1;
 193        }
 194        strbuf_add(buf, src, len);
 195
 196        free(to_free);
 197        return 1;
 198}
 199
 200struct filter_params {
 201        const char *src;
 202        unsigned long size;
 203        const char *cmd;
 204};
 205
 206static int filter_buffer(int fd, void *data)
 207{
 208        /*
 209         * Spawn cmd and feed the buffer contents through its stdin.
 210         */
 211        struct child_process child_process;
 212        struct filter_params *params = (struct filter_params *)data;
 213        int write_err, status;
 214        const char *argv[] = { "sh", "-c", params->cmd, NULL };
 215
 216        memset(&child_process, 0, sizeof(child_process));
 217        child_process.argv = argv;
 218        child_process.in = -1;
 219        child_process.out = fd;
 220
 221        if (start_command(&child_process))
 222                return error("cannot fork to run external filter %s", params->cmd);
 223
 224        write_err = (write_in_full(child_process.in, params->src, params->size) < 0);
 225        if (close(child_process.in))
 226                write_err = 1;
 227        if (write_err)
 228                error("cannot feed the input to external filter %s", params->cmd);
 229
 230        status = finish_command(&child_process);
 231        if (status)
 232                error("external filter %s failed %d", params->cmd, -status);
 233        return (write_err || status);
 234}
 235
 236static int apply_filter(const char *path, const char *src, size_t len,
 237                        struct strbuf *dst, const char *cmd)
 238{
 239        /*
 240         * Create a pipeline to have the command filter the buffer's
 241         * contents.
 242         *
 243         * (child --> cmd) --> us
 244         */
 245        int ret = 1;
 246        struct strbuf nbuf;
 247        struct async async;
 248        struct filter_params params;
 249
 250        if (!cmd)
 251                return 0;
 252
 253        memset(&async, 0, sizeof(async));
 254        async.proc = filter_buffer;
 255        async.data = &params;
 256        params.src = src;
 257        params.size = len;
 258        params.cmd = cmd;
 259
 260        fflush(NULL);
 261        if (start_async(&async))
 262                return 0;       /* error was already reported */
 263
 264        strbuf_init(&nbuf, 0);
 265        if (strbuf_read(&nbuf, async.out, len) < 0) {
 266                error("read from external filter %s failed", cmd);
 267                ret = 0;
 268        }
 269        if (close(async.out)) {
 270                error("read from external filter %s failed", cmd);
 271                ret = 0;
 272        }
 273        if (finish_async(&async)) {
 274                error("external filter %s failed", cmd);
 275                ret = 0;
 276        }
 277
 278        if (ret) {
 279                strbuf_swap(dst, &nbuf);
 280        }
 281        strbuf_release(&nbuf);
 282        return ret;
 283}
 284
 285static struct convert_driver {
 286        const char *name;
 287        struct convert_driver *next;
 288        char *smudge;
 289        char *clean;
 290} *user_convert, **user_convert_tail;
 291
 292static int read_convert_config(const char *var, const char *value)
 293{
 294        const char *ep, *name;
 295        int namelen;
 296        struct convert_driver *drv;
 297
 298        /*
 299         * External conversion drivers are configured using
 300         * "filter.<name>.variable".
 301         */
 302        if (prefixcmp(var, "filter.") || (ep = strrchr(var, '.')) == var + 6)
 303                return 0;
 304        name = var + 7;
 305        namelen = ep - name;
 306        for (drv = user_convert; drv; drv = drv->next)
 307                if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 308                        break;
 309        if (!drv) {
 310                drv = xcalloc(1, sizeof(struct convert_driver));
 311                drv->name = xmemdupz(name, namelen);
 312                *user_convert_tail = drv;
 313                user_convert_tail = &(drv->next);
 314        }
 315
 316        ep++;
 317
 318        /*
 319         * filter.<name>.smudge and filter.<name>.clean specifies
 320         * the command line:
 321         *
 322         *      command-line
 323         *
 324         * The command-line will not be interpolated in any way.
 325         */
 326
 327        if (!strcmp("smudge", ep)) {
 328                if (!value)
 329                        return error("%s: lacks value", var);
 330                drv->smudge = strdup(value);
 331                return 0;
 332        }
 333
 334        if (!strcmp("clean", ep)) {
 335                if (!value)
 336                        return error("%s: lacks value", var);
 337                drv->clean = strdup(value);
 338                return 0;
 339        }
 340        return 0;
 341}
 342
 343static void setup_convert_check(struct git_attr_check *check)
 344{
 345        static struct git_attr *attr_crlf;
 346        static struct git_attr *attr_ident;
 347        static struct git_attr *attr_filter;
 348
 349        if (!attr_crlf) {
 350                attr_crlf = git_attr("crlf", 4);
 351                attr_ident = git_attr("ident", 5);
 352                attr_filter = git_attr("filter", 6);
 353                user_convert_tail = &user_convert;
 354                git_config(read_convert_config);
 355        }
 356        check[0].attr = attr_crlf;
 357        check[1].attr = attr_ident;
 358        check[2].attr = attr_filter;
 359}
 360
 361static int count_ident(const char *cp, unsigned long size)
 362{
 363        /*
 364         * "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
 365         */
 366        int cnt = 0;
 367        char ch;
 368
 369        while (size) {
 370                ch = *cp++;
 371                size--;
 372                if (ch != '$')
 373                        continue;
 374                if (size < 3)
 375                        break;
 376                if (memcmp("Id", cp, 2))
 377                        continue;
 378                ch = cp[2];
 379                cp += 3;
 380                size -= 3;
 381                if (ch == '$')
 382                        cnt++; /* $Id$ */
 383                if (ch != ':')
 384                        continue;
 385
 386                /*
 387                 * "$Id: ... "; scan up to the closing dollar sign and discard.
 388                 */
 389                while (size) {
 390                        ch = *cp++;
 391                        size--;
 392                        if (ch == '$') {
 393                                cnt++;
 394                                break;
 395                        }
 396                }
 397        }
 398        return cnt;
 399}
 400
 401static int ident_to_git(const char *path, const char *src, size_t len,
 402                        struct strbuf *buf, int ident)
 403{
 404        char *dst, *dollar;
 405
 406        if (!ident || !count_ident(src, len))
 407                return 0;
 408
 409        /* only grow if not in place */
 410        if (strbuf_avail(buf) + buf->len < len)
 411                strbuf_grow(buf, len - buf->len);
 412        dst = buf->buf;
 413        for (;;) {
 414                dollar = memchr(src, '$', len);
 415                if (!dollar)
 416                        break;
 417                memcpy(dst, src, dollar + 1 - src);
 418                dst += dollar + 1 - src;
 419                len -= dollar + 1 - src;
 420                src  = dollar + 1;
 421
 422                if (len > 3 && !memcmp(src, "Id:", 3)) {
 423                        dollar = memchr(src + 3, '$', len - 3);
 424                        if (!dollar)
 425                                break;
 426                        memcpy(dst, "Id$", 3);
 427                        dst += 3;
 428                        len -= dollar + 1 - src;
 429                        src  = dollar + 1;
 430                }
 431        }
 432        memcpy(dst, src, len);
 433        strbuf_setlen(buf, dst + len - buf->buf);
 434        return 1;
 435}
 436
 437static int ident_to_worktree(const char *path, const char *src, size_t len,
 438                             struct strbuf *buf, int ident)
 439{
 440        unsigned char sha1[20];
 441        char *to_free = NULL, *dollar;
 442        int cnt;
 443
 444        if (!ident)
 445                return 0;
 446
 447        cnt = count_ident(src, len);
 448        if (!cnt)
 449                return 0;
 450
 451        /* are we "faking" in place editing ? */
 452        if (src == buf->buf)
 453                to_free = strbuf_detach(buf, NULL);
 454        hash_sha1_file(src, len, "blob", sha1);
 455
 456        strbuf_grow(buf, len + cnt * 43);
 457        for (;;) {
 458                /* step 1: run to the next '$' */
 459                dollar = memchr(src, '$', len);
 460                if (!dollar)
 461                        break;
 462                strbuf_add(buf, src, dollar + 1 - src);
 463                len -= dollar + 1 - src;
 464                src  = dollar + 1;
 465
 466                /* step 2: does it looks like a bit like Id:xxx$ or Id$ ? */
 467                if (len < 3 || memcmp("Id", src, 2))
 468                        continue;
 469
 470                /* step 3: skip over Id$ or Id:xxxxx$ */
 471                if (src[2] == '$') {
 472                        src += 3;
 473                        len -= 3;
 474                } else if (src[2] == ':') {
 475                        /*
 476                         * It's possible that an expanded Id has crept its way into the
 477                         * repository, we cope with that by stripping the expansion out
 478                         */
 479                        dollar = memchr(src + 3, '$', len - 3);
 480                        if (!dollar) {
 481                                /* incomplete keyword, no more '$', so just quit the loop */
 482                                break;
 483                        }
 484
 485                        len -= dollar + 1 - src;
 486                        src  = dollar + 1;
 487                } else {
 488                        /* it wasn't a "Id$" or "Id:xxxx$" */
 489                        continue;
 490                }
 491
 492                /* step 4: substitute */
 493                strbuf_addstr(buf, "Id: ");
 494                strbuf_add(buf, sha1_to_hex(sha1), 40);
 495                strbuf_addstr(buf, " $");
 496        }
 497        strbuf_add(buf, src, len);
 498
 499        free(to_free);
 500        return 1;
 501}
 502
 503static int git_path_check_crlf(const char *path, struct git_attr_check *check)
 504{
 505        const char *value = check->value;
 506
 507        if (ATTR_TRUE(value))
 508                return CRLF_TEXT;
 509        else if (ATTR_FALSE(value))
 510                return CRLF_BINARY;
 511        else if (ATTR_UNSET(value))
 512                ;
 513        else if (!strcmp(value, "input"))
 514                return CRLF_INPUT;
 515        return CRLF_GUESS;
 516}
 517
 518static struct convert_driver *git_path_check_convert(const char *path,
 519                                             struct git_attr_check *check)
 520{
 521        const char *value = check->value;
 522        struct convert_driver *drv;
 523
 524        if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
 525                return NULL;
 526        for (drv = user_convert; drv; drv = drv->next)
 527                if (!strcmp(value, drv->name))
 528                        return drv;
 529        return NULL;
 530}
 531
 532static int git_path_check_ident(const char *path, struct git_attr_check *check)
 533{
 534        const char *value = check->value;
 535
 536        return !!ATTR_TRUE(value);
 537}
 538
 539int convert_to_git(const char *path, const char *src, size_t len, struct strbuf *dst)
 540{
 541        struct git_attr_check check[3];
 542        int crlf = CRLF_GUESS;
 543        int ident = 0, ret = 0;
 544        char *filter = NULL;
 545
 546        setup_convert_check(check);
 547        if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
 548                struct convert_driver *drv;
 549                crlf = git_path_check_crlf(path, check + 0);
 550                ident = git_path_check_ident(path, check + 1);
 551                drv = git_path_check_convert(path, check + 2);
 552                if (drv && drv->clean)
 553                        filter = drv->clean;
 554        }
 555
 556        ret |= apply_filter(path, src, len, dst, filter);
 557        if (ret) {
 558                src = dst->buf;
 559                len = dst->len;
 560        }
 561        ret |= crlf_to_git(path, src, len, dst, crlf);
 562        if (ret) {
 563                src = dst->buf;
 564                len = dst->len;
 565        }
 566        return ret | ident_to_git(path, src, len, dst, ident);
 567}
 568
 569int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst)
 570{
 571        struct git_attr_check check[3];
 572        int crlf = CRLF_GUESS;
 573        int ident = 0, ret = 0;
 574        char *filter = NULL;
 575
 576        setup_convert_check(check);
 577        if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
 578                struct convert_driver *drv;
 579                crlf = git_path_check_crlf(path, check + 0);
 580                ident = git_path_check_ident(path, check + 1);
 581                drv = git_path_check_convert(path, check + 2);
 582                if (drv && drv->smudge)
 583                        filter = drv->smudge;
 584        }
 585
 586        ret |= ident_to_worktree(path, src, len, dst, ident);
 587        if (ret) {
 588                src = dst->buf;
 589                len = dst->len;
 590        }
 591        ret |= crlf_to_worktree(path, src, len, dst, crlf);
 592        if (ret) {
 593                src = dst->buf;
 594                len = dst->len;
 595        }
 596        return ret | apply_filter(path, src, len, dst, filter);
 597}