xdiff / xutils.con commit sequencer: make sequencer abort safer (1e41229)
   1/*
   2 *  LibXDiff by Davide Libenzi ( File Differential Library )
   3 *  Copyright (C) 2003  Davide Libenzi
   4 *
   5 *  This library is free software; you can redistribute it and/or
   6 *  modify it under the terms of the GNU Lesser General Public
   7 *  License as published by the Free Software Foundation; either
   8 *  version 2.1 of the License, or (at your option) any later version.
   9 *
  10 *  This library is distributed in the hope that it will be useful,
  11 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 *  Lesser General Public License for more details.
  14 *
  15 *  You should have received a copy of the GNU Lesser General Public
  16 *  License along with this library; if not, write to the Free Software
  17 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 *
  19 *  Davide Libenzi <davidel@xmailserver.org>
  20 *
  21 */
  22
  23#include <limits.h>
  24#include <assert.h>
  25#include "xinclude.h"
  26
  27
  28
  29
  30long xdl_bogosqrt(long n) {
  31        long i;
  32
  33        /*
  34         * Classical integer square root approximation using shifts.
  35         */
  36        for (i = 1; n > 0; n >>= 2)
  37                i <<= 1;
  38
  39        return i;
  40}
  41
  42
  43int xdl_emit_diffrec(char const *rec, long size, char const *pre, long psize,
  44                     xdemitcb_t *ecb) {
  45        int i = 2;
  46        mmbuffer_t mb[3];
  47
  48        mb[0].ptr = (char *) pre;
  49        mb[0].size = psize;
  50        mb[1].ptr = (char *) rec;
  51        mb[1].size = size;
  52        if (size > 0 && rec[size - 1] != '\n') {
  53                mb[2].ptr = (char *) "\n\\ No newline at end of file\n";
  54                mb[2].size = strlen(mb[2].ptr);
  55                i++;
  56        }
  57        if (ecb->outf(ecb->priv, mb, i) < 0) {
  58
  59                return -1;
  60        }
  61
  62        return 0;
  63}
  64
  65void *xdl_mmfile_first(mmfile_t *mmf, long *size)
  66{
  67        *size = mmf->size;
  68        return mmf->ptr;
  69}
  70
  71
  72long xdl_mmfile_size(mmfile_t *mmf)
  73{
  74        return mmf->size;
  75}
  76
  77
  78int xdl_cha_init(chastore_t *cha, long isize, long icount) {
  79
  80        cha->head = cha->tail = NULL;
  81        cha->isize = isize;
  82        cha->nsize = icount * isize;
  83        cha->ancur = cha->sncur = NULL;
  84        cha->scurr = 0;
  85
  86        return 0;
  87}
  88
  89
  90void xdl_cha_free(chastore_t *cha) {
  91        chanode_t *cur, *tmp;
  92
  93        for (cur = cha->head; (tmp = cur) != NULL;) {
  94                cur = cur->next;
  95                xdl_free(tmp);
  96        }
  97}
  98
  99
 100void *xdl_cha_alloc(chastore_t *cha) {
 101        chanode_t *ancur;
 102        void *data;
 103
 104        if (!(ancur = cha->ancur) || ancur->icurr == cha->nsize) {
 105                if (!(ancur = (chanode_t *) xdl_malloc(sizeof(chanode_t) + cha->nsize))) {
 106
 107                        return NULL;
 108                }
 109                ancur->icurr = 0;
 110                ancur->next = NULL;
 111                if (cha->tail)
 112                        cha->tail->next = ancur;
 113                if (!cha->head)
 114                        cha->head = ancur;
 115                cha->tail = ancur;
 116                cha->ancur = ancur;
 117        }
 118
 119        data = (char *) ancur + sizeof(chanode_t) + ancur->icurr;
 120        ancur->icurr += cha->isize;
 121
 122        return data;
 123}
 124
 125long xdl_guess_lines(mmfile_t *mf, long sample) {
 126        long nl = 0, size, tsize = 0;
 127        char const *data, *cur, *top;
 128
 129        if ((cur = data = xdl_mmfile_first(mf, &size)) != NULL) {
 130                for (top = data + size; nl < sample && cur < top; ) {
 131                        nl++;
 132                        if (!(cur = memchr(cur, '\n', top - cur)))
 133                                cur = top;
 134                        else
 135                                cur++;
 136                }
 137                tsize += (long) (cur - data);
 138        }
 139
 140        if (nl && tsize)
 141                nl = xdl_mmfile_size(mf) / (tsize / nl);
 142
 143        return nl + 1;
 144}
 145
 146int xdl_blankline(const char *line, long size, long flags)
 147{
 148        long i;
 149
 150        if (!(flags & XDF_WHITESPACE_FLAGS))
 151                return (size <= 1);
 152
 153        for (i = 0; i < size && XDL_ISSPACE(line[i]); i++)
 154                ;
 155
 156        return (i == size);
 157}
 158
 159int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags)
 160{
 161        int i1, i2;
 162
 163        if (s1 == s2 && !memcmp(l1, l2, s1))
 164                return 1;
 165        if (!(flags & XDF_WHITESPACE_FLAGS))
 166                return 0;
 167
 168        i1 = 0;
 169        i2 = 0;
 170
 171        /*
 172         * -w matches everything that matches with -b, and -b in turn
 173         * matches everything that matches with --ignore-space-at-eol.
 174         *
 175         * Each flavor of ignoring needs different logic to skip whitespaces
 176         * while we have both sides to compare.
 177         */
 178        if (flags & XDF_IGNORE_WHITESPACE) {
 179                goto skip_ws;
 180                while (i1 < s1 && i2 < s2) {
 181                        if (l1[i1++] != l2[i2++])
 182                                return 0;
 183                skip_ws:
 184                        while (i1 < s1 && XDL_ISSPACE(l1[i1]))
 185                                i1++;
 186                        while (i2 < s2 && XDL_ISSPACE(l2[i2]))
 187                                i2++;
 188                }
 189        } else if (flags & XDF_IGNORE_WHITESPACE_CHANGE) {
 190                while (i1 < s1 && i2 < s2) {
 191                        if (XDL_ISSPACE(l1[i1]) && XDL_ISSPACE(l2[i2])) {
 192                                /* Skip matching spaces and try again */
 193                                while (i1 < s1 && XDL_ISSPACE(l1[i1]))
 194                                        i1++;
 195                                while (i2 < s2 && XDL_ISSPACE(l2[i2]))
 196                                        i2++;
 197                                continue;
 198                        }
 199                        if (l1[i1++] != l2[i2++])
 200                                return 0;
 201                }
 202        } else if (flags & XDF_IGNORE_WHITESPACE_AT_EOL) {
 203                while (i1 < s1 && i2 < s2 && l1[i1] == l2[i2]) {
 204                        i1++;
 205                        i2++;
 206                }
 207        }
 208
 209        /*
 210         * After running out of one side, the remaining side must have
 211         * nothing but whitespace for the lines to match.  Note that
 212         * ignore-whitespace-at-eol case may break out of the loop
 213         * while there still are characters remaining on both lines.
 214         */
 215        if (i1 < s1) {
 216                while (i1 < s1 && XDL_ISSPACE(l1[i1]))
 217                        i1++;
 218                if (s1 != i1)
 219                        return 0;
 220        }
 221        if (i2 < s2) {
 222                while (i2 < s2 && XDL_ISSPACE(l2[i2]))
 223                        i2++;
 224                return (s2 == i2);
 225        }
 226        return 1;
 227}
 228
 229static unsigned long xdl_hash_record_with_whitespace(char const **data,
 230                char const *top, long flags) {
 231        unsigned long ha = 5381;
 232        char const *ptr = *data;
 233
 234        for (; ptr < top && *ptr != '\n'; ptr++) {
 235                if (XDL_ISSPACE(*ptr)) {
 236                        const char *ptr2 = ptr;
 237                        int at_eol;
 238                        while (ptr + 1 < top && XDL_ISSPACE(ptr[1])
 239                                        && ptr[1] != '\n')
 240                                ptr++;
 241                        at_eol = (top <= ptr + 1 || ptr[1] == '\n');
 242                        if (flags & XDF_IGNORE_WHITESPACE)
 243                                ; /* already handled */
 244                        else if (flags & XDF_IGNORE_WHITESPACE_CHANGE
 245                                 && !at_eol) {
 246                                ha += (ha << 5);
 247                                ha ^= (unsigned long) ' ';
 248                        }
 249                        else if (flags & XDF_IGNORE_WHITESPACE_AT_EOL
 250                                 && !at_eol) {
 251                                while (ptr2 != ptr + 1) {
 252                                        ha += (ha << 5);
 253                                        ha ^= (unsigned long) *ptr2;
 254                                        ptr2++;
 255                                }
 256                        }
 257                        continue;
 258                }
 259                ha += (ha << 5);
 260                ha ^= (unsigned long) *ptr;
 261        }
 262        *data = ptr < top ? ptr + 1: ptr;
 263
 264        return ha;
 265}
 266
 267#ifdef XDL_FAST_HASH
 268
 269#define REPEAT_BYTE(x)  ((~0ul / 0xff) * (x))
 270
 271#define ONEBYTES        REPEAT_BYTE(0x01)
 272#define NEWLINEBYTES    REPEAT_BYTE(0x0a)
 273#define HIGHBITS        REPEAT_BYTE(0x80)
 274
 275/* Return the high bit set in the first byte that is a zero */
 276static inline unsigned long has_zero(unsigned long a)
 277{
 278        return ((a - ONEBYTES) & ~a) & HIGHBITS;
 279}
 280
 281static inline long count_masked_bytes(unsigned long mask)
 282{
 283        if (sizeof(long) == 8) {
 284                /*
 285                 * Jan Achrenius on G+: microoptimized version of
 286                 * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
 287                 * that works for the bytemasks without having to
 288                 * mask them first.
 289                 */
 290                /*
 291                 * return mask * 0x0001020304050608 >> 56;
 292                 *
 293                 * Doing it like this avoids warnings on 32-bit machines.
 294                 */
 295                long a = (REPEAT_BYTE(0x01) / 0xff + 1);
 296                return mask * a >> (sizeof(long) * 7);
 297        } else {
 298                /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
 299                /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
 300                long a = (0x0ff0001 + mask) >> 23;
 301                /* Fix the 1 for 00 case */
 302                return a & mask;
 303        }
 304}
 305
 306unsigned long xdl_hash_record(char const **data, char const *top, long flags)
 307{
 308        unsigned long hash = 5381;
 309        unsigned long a = 0, mask = 0;
 310        char const *ptr = *data;
 311        char const *end = top - sizeof(unsigned long) + 1;
 312
 313        if (flags & XDF_WHITESPACE_FLAGS)
 314                return xdl_hash_record_with_whitespace(data, top, flags);
 315
 316        ptr -= sizeof(unsigned long);
 317        do {
 318                hash += hash << 5;
 319                hash ^= a;
 320                ptr += sizeof(unsigned long);
 321                if (ptr >= end)
 322                        break;
 323                a = *(unsigned long *)ptr;
 324                /* Do we have any '\n' bytes in this word? */
 325                mask = has_zero(a ^ NEWLINEBYTES);
 326        } while (!mask);
 327
 328        if (ptr >= end) {
 329                /*
 330                 * There is only a partial word left at the end of the
 331                 * buffer. Because we may work with a memory mapping,
 332                 * we have to grab the rest byte by byte instead of
 333                 * blindly reading it.
 334                 *
 335                 * To avoid problems with masking in a signed value,
 336                 * we use an unsigned char here.
 337                 */
 338                const char *p;
 339                for (p = top - 1; p >= ptr; p--)
 340                        a = (a << 8) + *((const unsigned char *)p);
 341                mask = has_zero(a ^ NEWLINEBYTES);
 342                if (!mask)
 343                        /*
 344                         * No '\n' found in the partial word.  Make a
 345                         * mask that matches what we read.
 346                         */
 347                        mask = 1UL << (8 * (top - ptr) + 7);
 348        }
 349
 350        /* The mask *below* the first high bit set */
 351        mask = (mask - 1) & ~mask;
 352        mask >>= 7;
 353        hash += hash << 5;
 354        hash ^= a & mask;
 355
 356        /* Advance past the last (possibly partial) word */
 357        ptr += count_masked_bytes(mask);
 358
 359        if (ptr < top) {
 360                assert(*ptr == '\n');
 361                ptr++;
 362        }
 363
 364        *data = ptr;
 365
 366        return hash;
 367}
 368
 369#else /* XDL_FAST_HASH */
 370
 371unsigned long xdl_hash_record(char const **data, char const *top, long flags) {
 372        unsigned long ha = 5381;
 373        char const *ptr = *data;
 374
 375        if (flags & XDF_WHITESPACE_FLAGS)
 376                return xdl_hash_record_with_whitespace(data, top, flags);
 377
 378        for (; ptr < top && *ptr != '\n'; ptr++) {
 379                ha += (ha << 5);
 380                ha ^= (unsigned long) *ptr;
 381        }
 382        *data = ptr < top ? ptr + 1: ptr;
 383
 384        return ha;
 385}
 386
 387#endif /* XDL_FAST_HASH */
 388
 389unsigned int xdl_hashbits(unsigned int size) {
 390        unsigned int val = 1, bits = 0;
 391
 392        for (; val < size && bits < CHAR_BIT * sizeof(unsigned int); val <<= 1, bits++);
 393        return bits ? bits: 1;
 394}
 395
 396
 397int xdl_num_out(char *out, long val) {
 398        char *ptr, *str = out;
 399        char buf[32];
 400
 401        ptr = buf + sizeof(buf) - 1;
 402        *ptr = '\0';
 403        if (val < 0) {
 404                *--ptr = '-';
 405                val = -val;
 406        }
 407        for (; val && ptr > buf; val /= 10)
 408                *--ptr = "0123456789"[val % 10];
 409        if (*ptr)
 410                for (; *ptr; ptr++, str++)
 411                        *str = *ptr;
 412        else
 413                *str++ = '0';
 414        *str = '\0';
 415
 416        return str - out;
 417}
 418
 419int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
 420                      const char *func, long funclen, xdemitcb_t *ecb) {
 421        int nb = 0;
 422        mmbuffer_t mb;
 423        char buf[128];
 424
 425        memcpy(buf, "@@ -", 4);
 426        nb += 4;
 427
 428        nb += xdl_num_out(buf + nb, c1 ? s1: s1 - 1);
 429
 430        if (c1 != 1) {
 431                memcpy(buf + nb, ",", 1);
 432                nb += 1;
 433
 434                nb += xdl_num_out(buf + nb, c1);
 435        }
 436
 437        memcpy(buf + nb, " +", 2);
 438        nb += 2;
 439
 440        nb += xdl_num_out(buf + nb, c2 ? s2: s2 - 1);
 441
 442        if (c2 != 1) {
 443                memcpy(buf + nb, ",", 1);
 444                nb += 1;
 445
 446                nb += xdl_num_out(buf + nb, c2);
 447        }
 448
 449        memcpy(buf + nb, " @@", 3);
 450        nb += 3;
 451        if (func && funclen) {
 452                buf[nb++] = ' ';
 453                if (funclen > sizeof(buf) - nb - 1)
 454                        funclen = sizeof(buf) - nb - 1;
 455                memcpy(buf + nb, func, funclen);
 456                nb += funclen;
 457        }
 458        buf[nb++] = '\n';
 459
 460        mb.ptr = buf;
 461        mb.size = nb;
 462        if (ecb->outf(ecb->priv, &mb, 1) < 0)
 463                return -1;
 464
 465        return 0;
 466}
 467
 468int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,
 469                int line1, int count1, int line2, int count2)
 470{
 471        /*
 472         * This probably does not work outside Git, since
 473         * we have a very simple mmfile structure.
 474         *
 475         * Note: ideally, we would reuse the prepared environment, but
 476         * the libxdiff interface does not (yet) allow for diffing only
 477         * ranges of lines instead of the whole files.
 478         */
 479        mmfile_t subfile1, subfile2;
 480        xdfenv_t env;
 481
 482        subfile1.ptr = (char *)diff_env->xdf1.recs[line1 - 1]->ptr;
 483        subfile1.size = diff_env->xdf1.recs[line1 + count1 - 2]->ptr +
 484                diff_env->xdf1.recs[line1 + count1 - 2]->size - subfile1.ptr;
 485        subfile2.ptr = (char *)diff_env->xdf2.recs[line2 - 1]->ptr;
 486        subfile2.size = diff_env->xdf2.recs[line2 + count2 - 2]->ptr +
 487                diff_env->xdf2.recs[line2 + count2 - 2]->size - subfile2.ptr;
 488        if (xdl_do_diff(&subfile1, &subfile2, xpp, &env) < 0)
 489                return -1;
 490
 491        memcpy(diff_env->xdf1.rchg + line1 - 1, env.xdf1.rchg, count1);
 492        memcpy(diff_env->xdf2.rchg + line2 - 1, env.xdf2.rchg, count2);
 493
 494        xdl_free_env(&env);
 495
 496        return 0;
 497}