Andrew's git / gitweb.git / convert.c
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convert.con commit Documentation: lost-found is now deprecated. (0bf15e7)
   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
 195struct filter_params {
 196        const char *src;
 197        unsigned long size;
 198        const char *cmd;
 199};
 200
 201static int filter_buffer(int fd, void *data)
 202{
 203        /*
 204         * Spawn cmd and feed the buffer contents through its stdin.
 205         */
 206        struct child_process child_process;
 207        struct filter_params *params = (struct filter_params *)data;
 208        int write_err, status;
 209        const char *argv[] = { "sh", "-c", params->cmd, NULL };
 210
 211        memset(&child_process, 0, sizeof(child_process));
 212        child_process.argv = argv;
 213        child_process.in = -1;
 214        child_process.out = fd;
 215
 216        if (start_command(&child_process))
 217                return error("cannot fork to run external filter %s", params->cmd);
 218
 219        write_err = (write_in_full(child_process.in, params->src, params->size) < 0);
 220        if (close(child_process.in))
 221                write_err = 1;
 222        if (write_err)
 223                error("cannot feed the input to external filter %s", params->cmd);
 224
 225        status = finish_command(&child_process);
 226        if (status)
 227                error("external filter %s failed %d", params->cmd, -status);
 228        return (write_err || status);
 229}
 230
 231static int apply_filter(const char *path, const char *src, size_t len,
 232                        struct strbuf *dst, const char *cmd)
 233{
 234        /*
 235         * Create a pipeline to have the command filter the buffer's
 236         * contents.
 237         *
 238         * (child --> cmd) --> us
 239         */
 240        int ret = 1;
 241        struct strbuf nbuf;
 242        struct async async;
 243        struct filter_params params;
 244
 245        if (!cmd)
 246                return 0;
 247
 248        memset(&async, 0, sizeof(async));
 249        async.proc = filter_buffer;
 250        async.data = &params;
 251        params.src = src;
 252        params.size = len;
 253        params.cmd = cmd;
 254
 255        fflush(NULL);
 256        if (start_async(&async))
 257                return 0;       /* error was already reported */
 258
 259        strbuf_init(&nbuf, 0);
 260        if (strbuf_read(&nbuf, async.out, len) < 0) {
 261                error("read from external filter %s failed", cmd);
 262                ret = 0;
 263        }
 264        if (close(async.out)) {
 265                error("read from external filter %s failed", cmd);
 266                ret = 0;
 267        }
 268        if (finish_async(&async)) {
 269                error("external filter %s failed", cmd);
 270                ret = 0;
 271        }
 272
 273        if (ret) {
 274                strbuf_swap(dst, &nbuf);
 275        }
 276        strbuf_release(&nbuf);
 277        return ret;
 278}
 279
 280static struct convert_driver {
 281        const char *name;
 282        struct convert_driver *next;
 283        char *smudge;
 284        char *clean;
 285} *user_convert, **user_convert_tail;
 286
 287static int read_convert_config(const char *var, const char *value)
 288{
 289        const char *ep, *name;
 290        int namelen;
 291        struct convert_driver *drv;
 292
 293        /*
 294         * External conversion drivers are configured using
 295         * "filter.<name>.variable".
 296         */
 297        if (prefixcmp(var, "filter.") || (ep = strrchr(var, '.')) == var + 6)
 298                return 0;
 299        name = var + 7;
 300        namelen = ep - name;
 301        for (drv = user_convert; drv; drv = drv->next)
 302                if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 303                        break;
 304        if (!drv) {
 305                drv = xcalloc(1, sizeof(struct convert_driver));
 306                drv->name = xmemdupz(name, namelen);
 307                *user_convert_tail = drv;
 308                user_convert_tail = &(drv->next);
 309        }
 310
 311        ep++;
 312
 313        /*
 314         * filter.<name>.smudge and filter.<name>.clean specifies
 315         * the command line:
 316         *
 317         *      command-line
 318         *
 319         * The command-line will not be interpolated in any way.
 320         */
 321
 322        if (!strcmp("smudge", ep)) {
 323                if (!value)
 324                        return error("%s: lacks value", var);
 325                drv->smudge = strdup(value);
 326                return 0;
 327        }
 328
 329        if (!strcmp("clean", ep)) {
 330                if (!value)
 331                        return error("%s: lacks value", var);
 332                drv->clean = strdup(value);
 333                return 0;
 334        }
 335        return 0;
 336}
 337
 338static void setup_convert_check(struct git_attr_check *check)
 339{
 340        static struct git_attr *attr_crlf;
 341        static struct git_attr *attr_ident;
 342        static struct git_attr *attr_filter;
 343
 344        if (!attr_crlf) {
 345                attr_crlf = git_attr("crlf", 4);
 346                attr_ident = git_attr("ident", 5);
 347                attr_filter = git_attr("filter", 6);
 348                user_convert_tail = &user_convert;
 349                git_config(read_convert_config);
 350        }
 351        check[0].attr = attr_crlf;
 352        check[1].attr = attr_ident;
 353        check[2].attr = attr_filter;
 354}
 355
 356static int count_ident(const char *cp, unsigned long size)
 357{
 358        /*
 359         * "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
 360         */
 361        int cnt = 0;
 362        char ch;
 363
 364        while (size) {
 365                ch = *cp++;
 366                size--;
 367                if (ch != '$')
 368                        continue;
 369                if (size < 3)
 370                        break;
 371                if (memcmp("Id", cp, 2))
 372                        continue;
 373                ch = cp[2];
 374                cp += 3;
 375                size -= 3;
 376                if (ch == '$')
 377                        cnt++; /* $Id$ */
 378                if (ch != ':')
 379                        continue;
 380
 381                /*
 382                 * "$Id: ... "; scan up to the closing dollar sign and discard.
 383                 */
 384                while (size) {
 385                        ch = *cp++;
 386                        size--;
 387                        if (ch == '$') {
 388                                cnt++;
 389                                break;
 390                        }
 391                }
 392        }
 393        return cnt;
 394}
 395
 396static int ident_to_git(const char *path, const char *src, size_t len,
 397                        struct strbuf *buf, int ident)
 398{
 399        char *dst, *dollar;
 400
 401        if (!ident || !count_ident(src, len))
 402                return 0;
 403
 404        /* only grow if not in place */
 405        if (strbuf_avail(buf) + buf->len < len)
 406                strbuf_grow(buf, len - buf->len);
 407        dst = buf->buf;
 408        for (;;) {
 409                dollar = memchr(src, '$', len);
 410                if (!dollar)
 411                        break;
 412                memcpy(dst, src, dollar + 1 - src);
 413                dst += dollar + 1 - src;
 414                len -= dollar + 1 - src;
 415                src  = dollar + 1;
 416
 417                if (len > 3 && !memcmp(src, "Id:", 3)) {
 418                        dollar = memchr(src + 3, '$', len - 3);
 419                        if (!dollar)
 420                                break;
 421                        memcpy(dst, "Id$", 3);
 422                        dst += 3;
 423                        len -= dollar + 1 - src;
 424                        src  = dollar + 1;
 425                }
 426        }
 427        memcpy(dst, src, len);
 428        strbuf_setlen(buf, dst + len - buf->buf);
 429        return 1;
 430}
 431
 432static int ident_to_worktree(const char *path, const char *src, size_t len,
 433                             struct strbuf *buf, int ident)
 434{
 435        unsigned char sha1[20];
 436        char *to_free = NULL, *dollar;
 437        int cnt;
 438
 439        if (!ident)
 440                return 0;
 441
 442        cnt = count_ident(src, len);
 443        if (!cnt)
 444                return 0;
 445
 446        /* are we "faking" in place editing ? */
 447        if (src == buf->buf)
 448                to_free = strbuf_detach(buf, NULL);
 449        hash_sha1_file(src, len, "blob", sha1);
 450
 451        strbuf_grow(buf, len + cnt * 43);
 452        for (;;) {
 453                /* step 1: run to the next '$' */
 454                dollar = memchr(src, '$', len);
 455                if (!dollar)
 456                        break;
 457                strbuf_add(buf, src, dollar + 1 - src);
 458                len -= dollar + 1 - src;
 459                src  = dollar + 1;
 460
 461                /* step 2: does it looks like a bit like Id:xxx$ or Id$ ? */
 462                if (len < 3 || memcmp("Id", src, 2))
 463                        continue;
 464
 465                /* step 3: skip over Id$ or Id:xxxxx$ */
 466                if (src[2] == '$') {
 467                        src += 3;
 468                        len -= 3;
 469                } else if (src[2] == ':') {
 470                        /*
 471                         * It's possible that an expanded Id has crept its way into the
 472                         * repository, we cope with that by stripping the expansion out
 473                         */
 474                        dollar = memchr(src + 3, '$', len - 3);
 475                        if (!dollar) {
 476                                /* incomplete keyword, no more '$', so just quit the loop */
 477                                break;
 478                        }
 479
 480                        len -= dollar + 1 - src;
 481                        src  = dollar + 1;
 482                } else {
 483                        /* it wasn't a "Id$" or "Id:xxxx$" */
 484                        continue;
 485                }
 486
 487                /* step 4: substitute */
 488                strbuf_addstr(buf, "Id: ");
 489                strbuf_add(buf, sha1_to_hex(sha1), 40);
 490                strbuf_addstr(buf, " $");
 491        }
 492        strbuf_add(buf, src, len);
 493
 494        free(to_free);
 495        return 1;
 496}
 497
 498static int git_path_check_crlf(const char *path, struct git_attr_check *check)
 499{
 500        const char *value = check->value;
 501
 502        if (ATTR_TRUE(value))
 503                return CRLF_TEXT;
 504        else if (ATTR_FALSE(value))
 505                return CRLF_BINARY;
 506        else if (ATTR_UNSET(value))
 507                ;
 508        else if (!strcmp(value, "input"))
 509                return CRLF_INPUT;
 510        return CRLF_GUESS;
 511}
 512
 513static struct convert_driver *git_path_check_convert(const char *path,
 514                                             struct git_attr_check *check)
 515{
 516        const char *value = check->value;
 517        struct convert_driver *drv;
 518
 519        if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
 520                return NULL;
 521        for (drv = user_convert; drv; drv = drv->next)
 522                if (!strcmp(value, drv->name))
 523                        return drv;
 524        return NULL;
 525}
 526
 527static int git_path_check_ident(const char *path, struct git_attr_check *check)
 528{
 529        const char *value = check->value;
 530
 531        return !!ATTR_TRUE(value);
 532}
 533
 534int convert_to_git(const char *path, const char *src, size_t len, struct strbuf *dst)
 535{
 536        struct git_attr_check check[3];
 537        int crlf = CRLF_GUESS;
 538        int ident = 0, ret = 0;
 539        char *filter = NULL;
 540
 541        setup_convert_check(check);
 542        if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
 543                struct convert_driver *drv;
 544                crlf = git_path_check_crlf(path, check + 0);
 545                ident = git_path_check_ident(path, check + 1);
 546                drv = git_path_check_convert(path, check + 2);
 547                if (drv && drv->clean)
 548                        filter = drv->clean;
 549        }
 550
 551        ret |= apply_filter(path, src, len, dst, filter);
 552        if (ret) {
 553                src = dst->buf;
 554                len = dst->len;
 555        }
 556        ret |= crlf_to_git(path, src, len, dst, crlf);
 557        if (ret) {
 558                src = dst->buf;
 559                len = dst->len;
 560        }
 561        return ret | ident_to_git(path, src, len, dst, ident);
 562}
 563
 564int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst)
 565{
 566        struct git_attr_check check[3];
 567        int crlf = CRLF_GUESS;
 568        int ident = 0, ret = 0;
 569        char *filter = NULL;
 570
 571        setup_convert_check(check);
 572        if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
 573                struct convert_driver *drv;
 574                crlf = git_path_check_crlf(path, check + 0);
 575                ident = git_path_check_ident(path, check + 1);
 576                drv = git_path_check_convert(path, check + 2);
 577                if (drv && drv->smudge)
 578                        filter = drv->smudge;
 579        }
 580
 581        ret |= ident_to_worktree(path, src, len, dst, ident);
 582        if (ret) {
 583                src = dst->buf;
 584                len = dst->len;
 585        }
 586        ret |= crlf_to_worktree(path, src, len, dst, crlf);
 587        if (ret) {
 588                src = dst->buf;
 589                len = dst->len;
 590        }
 591        return ret | apply_filter(path, src, len, dst, filter);
 592}