Andrew's git / gitweb.git / convert.c
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convert.con commit Use start_command() to run content filters instead of explicit fork/exec. (dc1bfdc)
   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        /* CR, LF and CRLF counts */
  21        unsigned 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                        default:
  55                                stats->nonprintable++;
  56                        }
  57                }
  58                else
  59                        stats->printable++;
  60        }
  61}
  62
  63/*
  64 * The same heuristics as diff.c::mmfile_is_binary()
  65 */
  66static int is_binary(unsigned long size, struct text_stat *stats)
  67{
  68
  69        if ((stats->printable >> 7) < stats->nonprintable)
  70                return 1;
  71        /*
  72         * Other heuristics? Average line length might be relevant,
  73         * as might LF vs CR vs CRLF counts..
  74         *
  75         * NOTE! It might be normal to have a low ratio of CRLF to LF
  76         * (somebody starts with a LF-only file and edits it with an editor
  77         * that adds CRLF only to lines that are added..). But do  we
  78         * want to support CR-only? Probably not.
  79         */
  80        return 0;
  81}
  82
  83static int crlf_to_git(const char *path, const char *src, size_t len,
  84                       struct strbuf *buf, int action)
  85{
  86        struct text_stat stats;
  87        char *dst;
  88
  89        if ((action == CRLF_BINARY) || !auto_crlf || !len)
  90                return 0;
  91
  92        gather_stats(src, len, &stats);
  93        /* No CR? Nothing to convert, regardless. */
  94        if (!stats.cr)
  95                return 0;
  96
  97        if (action == CRLF_GUESS) {
  98                /*
  99                 * We're currently not going to even try to convert stuff
 100                 * that has bare CR characters. Does anybody do that crazy
 101                 * stuff?
 102                 */
 103                if (stats.cr != stats.crlf)
 104                        return 0;
 105
 106                /*
 107                 * And add some heuristics for binary vs text, of course...
 108                 */
 109                if (is_binary(len, &stats))
 110                        return 0;
 111        }
 112
 113        /* only grow if not in place */
 114        if (strbuf_avail(buf) + buf->len < len)
 115                strbuf_grow(buf, len - buf->len);
 116        dst = buf->buf;
 117        if (action == CRLF_GUESS) {
 118                /*
 119                 * If we guessed, we already know we rejected a file with
 120                 * lone CR, and we can strip a CR without looking at what
 121                 * follow it.
 122                 */
 123                do {
 124                        unsigned char c = *src++;
 125                        if (c != '\r')
 126                                *dst++ = c;
 127                } while (--len);
 128        } else {
 129                do {
 130                        unsigned char c = *src++;
 131                        if (! (c == '\r' && (1 < len && *src == '\n')))
 132                                *dst++ = c;
 133                } while (--len);
 134        }
 135        strbuf_setlen(buf, dst - buf->buf);
 136        return 1;
 137}
 138
 139static int crlf_to_worktree(const char *path, const char *src, size_t len,
 140                            struct strbuf *buf, int action)
 141{
 142        char *to_free = NULL;
 143        struct text_stat stats;
 144
 145        if ((action == CRLF_BINARY) || (action == CRLF_INPUT) ||
 146            auto_crlf <= 0)
 147                return 0;
 148
 149        if (!len)
 150                return 0;
 151
 152        gather_stats(src, len, &stats);
 153
 154        /* No LF? Nothing to convert, regardless. */
 155        if (!stats.lf)
 156                return 0;
 157
 158        /* Was it already in CRLF format? */
 159        if (stats.lf == stats.crlf)
 160                return 0;
 161
 162        if (action == CRLF_GUESS) {
 163                /* If we have any bare CR characters, we're not going to touch it */
 164                if (stats.cr != stats.crlf)
 165                        return 0;
 166
 167                if (is_binary(len, &stats))
 168                        return 0;
 169        }
 170
 171        /* are we "faking" in place editing ? */
 172        if (src == buf->buf)
 173                to_free = strbuf_detach(buf, NULL);
 174
 175        strbuf_grow(buf, len + stats.lf - stats.crlf);
 176        for (;;) {
 177                const char *nl = memchr(src, '\n', len);
 178                if (!nl)
 179                        break;
 180                if (nl > src && nl[-1] == '\r') {
 181                        strbuf_add(buf, src, nl + 1 - src);
 182                } else {
 183                        strbuf_add(buf, src, nl - src);
 184                        strbuf_addstr(buf, "\r\n");
 185                }
 186                len -= nl + 1 - src;
 187                src  = nl + 1;
 188        }
 189        strbuf_add(buf, src, len);
 190
 191        free(to_free);
 192        return 1;
 193}
 194
 195static int filter_buffer(const char *path, const char *src,
 196                         unsigned long size, const char *cmd)
 197{
 198        /*
 199         * Spawn cmd and feed the buffer contents through its stdin.
 200         */
 201        struct child_process child_process;
 202        int write_err, status;
 203        const char *argv[] = { "sh", "-c", cmd, NULL };
 204
 205        memset(&child_process, 0, sizeof(child_process));
 206        child_process.argv = argv;
 207        child_process.in = -1;
 208
 209        if (start_command(&child_process))
 210                return error("cannot fork to run external filter %s", cmd);
 211
 212        write_err = (write_in_full(child_process.in, src, size) < 0);
 213        if (close(child_process.in))
 214                write_err = 1;
 215        if (write_err)
 216                error("cannot feed the input to external filter %s", cmd);
 217
 218        status = finish_command(&child_process);
 219        if (status)
 220                error("external filter %s failed %d", cmd, -status);
 221        return (write_err || status);
 222}
 223
 224static int apply_filter(const char *path, const char *src, size_t len,
 225                        struct strbuf *dst, const char *cmd)
 226{
 227        /*
 228         * Create a pipeline to have the command filter the buffer's
 229         * contents.
 230         *
 231         * (child --> cmd) --> us
 232         */
 233        int pipe_feed[2];
 234        int status, ret = 1;
 235        struct child_process child_process;
 236        struct strbuf nbuf;
 237
 238        if (!cmd)
 239                return 0;
 240
 241        memset(&child_process, 0, sizeof(child_process));
 242
 243        if (pipe(pipe_feed) < 0) {
 244                error("cannot create pipe to run external filter %s", cmd);
 245                return 0;
 246        }
 247
 248        fflush(NULL);
 249        child_process.pid = fork();
 250        if (child_process.pid < 0) {
 251                error("cannot fork to run external filter %s", cmd);
 252                close(pipe_feed[0]);
 253                close(pipe_feed[1]);
 254                return 0;
 255        }
 256        if (!child_process.pid) {
 257                dup2(pipe_feed[1], 1);
 258                close(pipe_feed[0]);
 259                close(pipe_feed[1]);
 260                exit(filter_buffer(path, src, len, cmd));
 261        }
 262        close(pipe_feed[1]);
 263
 264        strbuf_init(&nbuf, 0);
 265        if (strbuf_read(&nbuf, pipe_feed[0], len) < 0) {
 266                error("read from external filter %s failed", cmd);
 267                ret = 0;
 268        }
 269        if (close(pipe_feed[0])) {
 270                error("read from external filter %s failed", cmd);
 271                ret = 0;
 272        }
 273        status = finish_command(&child_process);
 274        if (status) {
 275                error("external filter %s failed %d", cmd, -status);
 276                ret = 0;
 277        }
 278
 279        if (ret) {
 280                strbuf_swap(dst, &nbuf);
 281        }
 282        strbuf_release(&nbuf);
 283        return ret;
 284}
 285
 286static struct convert_driver {
 287        const char *name;
 288        struct convert_driver *next;
 289        char *smudge;
 290        char *clean;
 291} *user_convert, **user_convert_tail;
 292
 293static int read_convert_config(const char *var, const char *value)
 294{
 295        const char *ep, *name;
 296        int namelen;
 297        struct convert_driver *drv;
 298
 299        /*
 300         * External conversion drivers are configured using
 301         * "filter.<name>.variable".
 302         */
 303        if (prefixcmp(var, "filter.") || (ep = strrchr(var, '.')) == var + 6)
 304                return 0;
 305        name = var + 7;
 306        namelen = ep - name;
 307        for (drv = user_convert; drv; drv = drv->next)
 308                if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 309                        break;
 310        if (!drv) {
 311                drv = xcalloc(1, sizeof(struct convert_driver));
 312                drv->name = xmemdupz(name, namelen);
 313                *user_convert_tail = drv;
 314                user_convert_tail = &(drv->next);
 315        }
 316
 317        ep++;
 318
 319        /*
 320         * filter.<name>.smudge and filter.<name>.clean specifies
 321         * the command line:
 322         *
 323         *      command-line
 324         *
 325         * The command-line will not be interpolated in any way.
 326         */
 327
 328        if (!strcmp("smudge", ep)) {
 329                if (!value)
 330                        return error("%s: lacks value", var);
 331                drv->smudge = strdup(value);
 332                return 0;
 333        }
 334
 335        if (!strcmp("clean", ep)) {
 336                if (!value)
 337                        return error("%s: lacks value", var);
 338                drv->clean = strdup(value);
 339                return 0;
 340        }
 341        return 0;
 342}
 343
 344static void setup_convert_check(struct git_attr_check *check)
 345{
 346        static struct git_attr *attr_crlf;
 347        static struct git_attr *attr_ident;
 348        static struct git_attr *attr_filter;
 349
 350        if (!attr_crlf) {
 351                attr_crlf = git_attr("crlf", 4);
 352                attr_ident = git_attr("ident", 5);
 353                attr_filter = git_attr("filter", 6);
 354                user_convert_tail = &user_convert;
 355                git_config(read_convert_config);
 356        }
 357        check[0].attr = attr_crlf;
 358        check[1].attr = attr_ident;
 359        check[2].attr = attr_filter;
 360}
 361
 362static int count_ident(const char *cp, unsigned long size)
 363{
 364        /*
 365         * "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
 366         */
 367        int cnt = 0;
 368        char ch;
 369
 370        while (size) {
 371                ch = *cp++;
 372                size--;
 373                if (ch != '$')
 374                        continue;
 375                if (size < 3)
 376                        break;
 377                if (memcmp("Id", cp, 2))
 378                        continue;
 379                ch = cp[2];
 380                cp += 3;
 381                size -= 3;
 382                if (ch == '$')
 383                        cnt++; /* $Id$ */
 384                if (ch != ':')
 385                        continue;
 386
 387                /*
 388                 * "$Id: ... "; scan up to the closing dollar sign and discard.
 389                 */
 390                while (size) {
 391                        ch = *cp++;
 392                        size--;
 393                        if (ch == '$') {
 394                                cnt++;
 395                                break;
 396                        }
 397                }
 398        }
 399        return cnt;
 400}
 401
 402static int ident_to_git(const char *path, const char *src, size_t len,
 403                        struct strbuf *buf, int ident)
 404{
 405        char *dst, *dollar;
 406
 407        if (!ident || !count_ident(src, len))
 408                return 0;
 409
 410        /* only grow if not in place */
 411        if (strbuf_avail(buf) + buf->len < len)
 412                strbuf_grow(buf, len - buf->len);
 413        dst = buf->buf;
 414        for (;;) {
 415                dollar = memchr(src, '$', len);
 416                if (!dollar)
 417                        break;
 418                memcpy(dst, src, dollar + 1 - src);
 419                dst += dollar + 1 - src;
 420                len -= dollar + 1 - src;
 421                src  = dollar + 1;
 422
 423                if (len > 3 && !memcmp(src, "Id:", 3)) {
 424                        dollar = memchr(src + 3, '$', len - 3);
 425                        if (!dollar)
 426                                break;
 427                        memcpy(dst, "Id$", 3);
 428                        dst += 3;
 429                        len -= dollar + 1 - src;
 430                        src  = dollar + 1;
 431                }
 432        }
 433        memcpy(dst, src, len);
 434        strbuf_setlen(buf, dst + len - buf->buf);
 435        return 1;
 436}
 437
 438static int ident_to_worktree(const char *path, const char *src, size_t len,
 439                             struct strbuf *buf, int ident)
 440{
 441        unsigned char sha1[20];
 442        char *to_free = NULL, *dollar;
 443        int cnt;
 444
 445        if (!ident)
 446                return 0;
 447
 448        cnt = count_ident(src, len);
 449        if (!cnt)
 450                return 0;
 451
 452        /* are we "faking" in place editing ? */
 453        if (src == buf->buf)
 454                to_free = strbuf_detach(buf, NULL);
 455        hash_sha1_file(src, len, "blob", sha1);
 456
 457        strbuf_grow(buf, len + cnt * 43);
 458        for (;;) {
 459                /* step 1: run to the next '$' */
 460                dollar = memchr(src, '$', len);
 461                if (!dollar)
 462                        break;
 463                strbuf_add(buf, src, dollar + 1 - src);
 464                len -= dollar + 1 - src;
 465                src  = dollar + 1;
 466
 467                /* step 2: does it looks like a bit like Id:xxx$ or Id$ ? */
 468                if (len < 3 || memcmp("Id", src, 2))
 469                        continue;
 470
 471                /* step 3: skip over Id$ or Id:xxxxx$ */
 472                if (src[2] == '$') {
 473                        src += 3;
 474                        len -= 3;
 475                } else if (src[2] == ':') {
 476                        /*
 477                         * It's possible that an expanded Id has crept its way into the
 478                         * repository, we cope with that by stripping the expansion out
 479                         */
 480                        dollar = memchr(src + 3, '$', len - 3);
 481                        if (!dollar) {
 482                                /* incomplete keyword, no more '$', so just quit the loop */
 483                                break;
 484                        }
 485
 486                        len -= dollar + 1 - src;
 487                        src  = dollar + 1;
 488                } else {
 489                        /* it wasn't a "Id$" or "Id:xxxx$" */
 490                        continue;
 491                }
 492
 493                /* step 4: substitute */
 494                strbuf_addstr(buf, "Id: ");
 495                strbuf_add(buf, sha1_to_hex(sha1), 40);
 496                strbuf_addstr(buf, " $");
 497        }
 498        strbuf_add(buf, src, len);
 499
 500        free(to_free);
 501        return 1;
 502}
 503
 504static int git_path_check_crlf(const char *path, struct git_attr_check *check)
 505{
 506        const char *value = check->value;
 507
 508        if (ATTR_TRUE(value))
 509                return CRLF_TEXT;
 510        else if (ATTR_FALSE(value))
 511                return CRLF_BINARY;
 512        else if (ATTR_UNSET(value))
 513                ;
 514        else if (!strcmp(value, "input"))
 515                return CRLF_INPUT;
 516        return CRLF_GUESS;
 517}
 518
 519static struct convert_driver *git_path_check_convert(const char *path,
 520                                             struct git_attr_check *check)
 521{
 522        const char *value = check->value;
 523        struct convert_driver *drv;
 524
 525        if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
 526                return NULL;
 527        for (drv = user_convert; drv; drv = drv->next)
 528                if (!strcmp(value, drv->name))
 529                        return drv;
 530        return NULL;
 531}
 532
 533static int git_path_check_ident(const char *path, struct git_attr_check *check)
 534{
 535        const char *value = check->value;
 536
 537        return !!ATTR_TRUE(value);
 538}
 539
 540int convert_to_git(const char *path, const char *src, size_t len, struct strbuf *dst)
 541{
 542        struct git_attr_check check[3];
 543        int crlf = CRLF_GUESS;
 544        int ident = 0, ret = 0;
 545        char *filter = NULL;
 546
 547        setup_convert_check(check);
 548        if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
 549                struct convert_driver *drv;
 550                crlf = git_path_check_crlf(path, check + 0);
 551                ident = git_path_check_ident(path, check + 1);
 552                drv = git_path_check_convert(path, check + 2);
 553                if (drv && drv->clean)
 554                        filter = drv->clean;
 555        }
 556
 557        ret |= apply_filter(path, src, len, dst, filter);
 558        if (ret) {
 559                src = dst->buf;
 560                len = dst->len;
 561        }
 562        ret |= crlf_to_git(path, src, len, dst, crlf);
 563        if (ret) {
 564                src = dst->buf;
 565                len = dst->len;
 566        }
 567        return ret | ident_to_git(path, src, len, dst, ident);
 568}
 569
 570int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst)
 571{
 572        struct git_attr_check check[3];
 573        int crlf = CRLF_GUESS;
 574        int ident = 0, ret = 0;
 575        char *filter = NULL;
 576
 577        setup_convert_check(check);
 578        if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
 579                struct convert_driver *drv;
 580                crlf = git_path_check_crlf(path, check + 0);
 581                ident = git_path_check_ident(path, check + 1);
 582                drv = git_path_check_convert(path, check + 2);
 583                if (drv && drv->smudge)
 584                        filter = drv->smudge;
 585        }
 586
 587        ret |= ident_to_worktree(path, src, len, dst, ident);
 588        if (ret) {
 589                src = dst->buf;
 590                len = dst->len;
 591        }
 592        ret |= crlf_to_worktree(path, src, len, dst, crlf);
 593        if (ret) {
 594                src = dst->buf;
 595                len = dst->len;
 596        }
 597        return ret | apply_filter(path, src, len, dst, filter);
 598}