Add libxdiff library

xdiff/xutils.c

+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003  Davide Libenzi
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#include <limits.h>
+#include <assert.h>
+#include "xinclude.h"
+
+
+
+
+long xdl_bogosqrt(long n) {
+        long i;
+
+        /*
+         * Classical integer square root approximation using shifts.
+         */
+        for (i = 1; n > 0; n >>= 2)
+                i <<= 1;
+
+        return i;
+}
+
+
+int xdl_emit_diffrec(char const *rec, long size, char const *pre, long psize,
+                     xdemitcb_t *ecb) {
+        int i = 2;
+        mmbuffer_t mb[3];
+
+        mb[0].ptr = (char *) pre;
+        mb[0].size = psize;
+        mb[1].ptr = (char *) rec;
+        mb[1].size = size;
+        if (size > 0 && rec[size - 1] != '\n') {
+                mb[2].ptr = (char *) "\n\\ No newline at end of file\n";
+                mb[2].size = strlen(mb[2].ptr);
+                i++;
+        }
+        if (ecb->outf(ecb->priv, mb, i) < 0) {
+
+                return -1;
+        }
+
+        return 0;
+}
+
+void *xdl_mmfile_first(mmfile_t *mmf, long *size)
+{
+        *size = mmf->size;
+        return mmf->ptr;
+}
+
+
+long xdl_mmfile_size(mmfile_t *mmf)
+{
+        return mmf->size;
+}
+
+
+int xdl_cha_init(chastore_t *cha, long isize, long icount) {
+
+        cha->head = cha->tail = NULL;
+        cha->isize = isize;
+        cha->nsize = icount * isize;
+        cha->ancur = cha->sncur = NULL;
+        cha->scurr = 0;
+
+        return 0;
+}
+
+
+void xdl_cha_free(chastore_t *cha) {
+        chanode_t *cur, *tmp;
+
+        for (cur = cha->head; (tmp = cur) != NULL;) {
+                cur = cur->next;
+                xdl_free(tmp);
+        }
+}
+
+
+void *xdl_cha_alloc(chastore_t *cha) {
+        chanode_t *ancur;
+        void *data;
+
+        if (!(ancur = cha->ancur) || ancur->icurr == cha->nsize) {
+                if (!(ancur = (chanode_t *) xdl_malloc(sizeof(chanode_t) + cha->nsize))) {
+
+                        return NULL;
+                }
+                ancur->icurr = 0;
+                ancur->next = NULL;
+                if (cha->tail)
+                        cha->tail->next = ancur;
+                if (!cha->head)
+                        cha->head = ancur;
+                cha->tail = ancur;
+                cha->ancur = ancur;
+        }
+
+        data = (char *) ancur + sizeof(chanode_t) + ancur->icurr;
+        ancur->icurr += cha->isize;
+
+        return data;
+}
+
+long xdl_guess_lines(mmfile_t *mf, long sample) {
+        long nl = 0, size, tsize = 0;
+        char const *data, *cur, *top;
+
+        if ((cur = data = xdl_mmfile_first(mf, &size)) != NULL) {
+                for (top = data + size; nl < sample && cur < top; ) {
+                        nl++;
+                        if (!(cur = memchr(cur, '\n', top - cur)))
+                                cur = top;
+                        else
+                                cur++;
+                }
+                tsize += (long) (cur - data);
+        }
+
+        if (nl && tsize)
+                nl = xdl_mmfile_size(mf) / (tsize / nl);
+
+        return nl + 1;
+}
+
+int xdl_blankline(const char *line, long size, long flags)
+{
+        long i;
+
+        if (!(flags & XDF_WHITESPACE_FLAGS))
+                return (size <= 1);
+
+        for (i = 0; i < size && XDL_ISSPACE(line[i]); i++)
+                ;
+
+        return (i == size);
+}
+
+int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags)
+{
+        int i1, i2;
+
+        if (s1 == s2 && !memcmp(l1, l2, s1))
+                return 1;
+        if (!(flags & XDF_WHITESPACE_FLAGS))
+                return 0;
+
+        i1 = 0;
+        i2 = 0;
+
+        /*
+         * -w matches everything that matches with -b, and -b in turn
+         * matches everything that matches with --ignore-space-at-eol.
+         *
+         * Each flavor of ignoring needs different logic to skip whitespaces
+         * while we have both sides to compare.
+         */
+        if (flags & XDF_IGNORE_WHITESPACE) {
+                goto skip_ws;
+                while (i1 < s1 && i2 < s2) {
+                        if (l1[i1++] != l2[i2++])
+                                return 0;
+                skip_ws:
+                        while (i1 < s1 && XDL_ISSPACE(l1[i1]))
+                                i1++;
+                        while (i2 < s2 && XDL_ISSPACE(l2[i2]))
+                                i2++;
+                }
+        } else if (flags & XDF_IGNORE_WHITESPACE_CHANGE) {
+                while (i1 < s1 && i2 < s2) {
+                        if (XDL_ISSPACE(l1[i1]) && XDL_ISSPACE(l2[i2])) {
+                                /* Skip matching spaces and try again */
+                                while (i1 < s1 && XDL_ISSPACE(l1[i1]))
+                                        i1++;
+                                while (i2 < s2 && XDL_ISSPACE(l2[i2]))
+                                        i2++;
+                                continue;
+                        }
+                        if (l1[i1++] != l2[i2++])
+                                return 0;
+                }
+        } else if (flags & XDF_IGNORE_WHITESPACE_AT_EOL) {
+                while (i1 < s1 && i2 < s2 && l1[i1++] == l2[i2++])
+                        ; /* keep going */
+        }
+
+        /*
+         * After running out of one side, the remaining side must have
+         * nothing but whitespace for the lines to match.  Note that
+         * ignore-whitespace-at-eol case may break out of the loop
+         * while there still are characters remaining on both lines.
+         */
+        if (i1 < s1) {
+                while (i1 < s1 && XDL_ISSPACE(l1[i1]))
+                        i1++;
+                if (s1 != i1)
+                        return 0;
+        }
+        if (i2 < s2) {
+                while (i2 < s2 && XDL_ISSPACE(l2[i2]))
+                        i2++;
+                return (s2 == i2);
+        }
+        return 1;
+}
+
+static unsigned long xdl_hash_record_with_whitespace(char const **data,
+                char const *top, long flags) {
+        unsigned long ha = 5381;
+        char const *ptr = *data;
+
+        for (; ptr < top && *ptr != '\n'; ptr++) {
+                if (XDL_ISSPACE(*ptr)) {
+                        const char *ptr2 = ptr;
+                        int at_eol;
+                        while (ptr + 1 < top && XDL_ISSPACE(ptr[1])
+                                        && ptr[1] != '\n')
+                                ptr++;
+                        at_eol = (top <= ptr + 1 || ptr[1] == '\n');
+                        if (flags & XDF_IGNORE_WHITESPACE)
+                                ; /* already handled */
+                        else if (flags & XDF_IGNORE_WHITESPACE_CHANGE
+                                 && !at_eol) {
+                                ha += (ha << 5);
+                                ha ^= (unsigned long) ' ';
+                        }
+                        else if (flags & XDF_IGNORE_WHITESPACE_AT_EOL
+                                 && !at_eol) {
+                                while (ptr2 != ptr + 1) {
+                                        ha += (ha << 5);
+                                        ha ^= (unsigned long) *ptr2;
+                                        ptr2++;
+                                }
+                        }
+                        continue;
+                }
+                ha += (ha << 5);
+                ha ^= (unsigned long) *ptr;
+        }
+        *data = ptr < top ? ptr + 1: ptr;
+
+        return ha;
+}
+
+#ifdef XDL_FAST_HASH
+
+#define REPEAT_BYTE(x)  ((~0ul / 0xff) * (x))
+
+#define ONEBYTES        REPEAT_BYTE(0x01)
+#define NEWLINEBYTES    REPEAT_BYTE(0x0a)
+#define HIGHBITS        REPEAT_BYTE(0x80)
+
+/* Return the high bit set in the first byte that is a zero */
+static inline unsigned long has_zero(unsigned long a)
+{
+        return ((a - ONEBYTES) & ~a) & HIGHBITS;
+}
+
+static inline long count_masked_bytes(unsigned long mask)
+{
+        if (sizeof(long) == 8) {
+                /*
+                 * Jan Achrenius on G+: microoptimized version of
+                 * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
+                 * that works for the bytemasks without having to
+                 * mask them first.
+                 */
+                /*
+                 * return mask * 0x0001020304050608 >> 56;
+                 *
+                 * Doing it like this avoids warnings on 32-bit machines.
+                 */
+                long a = (REPEAT_BYTE(0x01) / 0xff + 1);
+                return mask * a >> (sizeof(long) * 7);
+        } else {
+                /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
+                /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
+                long a = (0x0ff0001 + mask) >> 23;
+                /* Fix the 1 for 00 case */
+                return a & mask;
+        }
+}
+
+unsigned long xdl_hash_record(char const **data, char const *top, long flags)
+{
+        unsigned long hash = 5381;
+        unsigned long a = 0, mask = 0;
+        char const *ptr = *data;
+        char const *end = top - sizeof(unsigned long) + 1;
+
+        if (flags & XDF_WHITESPACE_FLAGS)
+                return xdl_hash_record_with_whitespace(data, top, flags);
+
+        ptr -= sizeof(unsigned long);
+        do {
+                hash += hash << 5;
+                hash ^= a;
+                ptr += sizeof(unsigned long);
+                if (ptr >= end)
+                        break;
+                a = *(unsigned long *)ptr;
+                /* Do we have any '\n' bytes in this word? */
+                mask = has_zero(a ^ NEWLINEBYTES);
+        } while (!mask);
+
+        if (ptr >= end) {
+                /*
+                 * There is only a partial word left at the end of the
+                 * buffer. Because we may work with a memory mapping,
+                 * we have to grab the rest byte by byte instead of
+                 * blindly reading it.
+                 *
+                 * To avoid problems with masking in a signed value,
+                 * we use an unsigned char here.
+                 */
+                const char *p;
+                for (p = top - 1; p >= ptr; p--)
+                        a = (a << 8) + *((const unsigned char *)p);
+                mask = has_zero(a ^ NEWLINEBYTES);
+                if (!mask)
+                        /*
+                         * No '\n' found in the partial word.  Make a
+                         * mask that matches what we read.
+                         */
+                        mask = 1UL << (8 * (top - ptr) + 7);
+        }
+
+        /* The mask *below* the first high bit set */
+        mask = (mask - 1) & ~mask;
+        mask >>= 7;
+        hash += hash << 5;
+        hash ^= a & mask;
+
+        /* Advance past the last (possibly partial) word */
+        ptr += count_masked_bytes(mask);
+
+        if (ptr < top) {
+                assert(*ptr == '\n');
+                ptr++;
+        }
+
+        *data = ptr;
+
+        return hash;
+}
+
+#else /* XDL_FAST_HASH */
+
+unsigned long xdl_hash_record(char const **data, char const *top, long flags) {
+        unsigned long ha = 5381;
+        char const *ptr = *data;
+
+        if (flags & XDF_WHITESPACE_FLAGS)
+                return xdl_hash_record_with_whitespace(data, top, flags);
+
+        for (; ptr < top && *ptr != '\n'; ptr++) {
+                ha += (ha << 5);
+                ha ^= (unsigned long) *ptr;
+        }
+        *data = ptr < top ? ptr + 1: ptr;
+
+        return ha;
+}
+
+#endif /* XDL_FAST_HASH */
+
+unsigned int xdl_hashbits(unsigned int size) {
+        unsigned int val = 1, bits = 0;
+
+        for (; val < size && bits < CHAR_BIT * sizeof(unsigned int); val <<= 1, bits++);
+        return bits ? bits: 1;
+}
+
+
+int xdl_num_out(char *out, long val) {
+        char *ptr, *str = out;
+        char buf[32];
+
+        ptr = buf + sizeof(buf) - 1;
+        *ptr = '\0';
+        if (val < 0) {
+                *--ptr = '-';
+                val = -val;
+        }
+        for (; val && ptr > buf; val /= 10)
+                *--ptr = "0123456789"[val % 10];
+        if (*ptr)
+                for (; *ptr; ptr++, str++)
+                        *str = *ptr;
+        else
+                *str++ = '0';
+        *str = '\0';
+
+        return str - out;
+}
+
+int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
+                      const char *func, long funclen, xdemitcb_t *ecb) {
+        int nb = 0;
+        mmbuffer_t mb;
+        char buf[128];
+
+        memcpy(buf, "@@ -", 4);
+        nb += 4;
+
+        nb += xdl_num_out(buf + nb, c1 ? s1: s1 - 1);
+
+        if (c1 != 1) {
+                memcpy(buf + nb, ",", 1);
+                nb += 1;
+
+                nb += xdl_num_out(buf + nb, c1);
+        }
+
+        memcpy(buf + nb, " +", 2);
+        nb += 2;
+
+        nb += xdl_num_out(buf + nb, c2 ? s2: s2 - 1);
+
+        if (c2 != 1) {
+                memcpy(buf + nb, ",", 1);
+                nb += 1;
+
+                nb += xdl_num_out(buf + nb, c2);
+        }
+
+        memcpy(buf + nb, " @@", 3);
+        nb += 3;
+        if (func && funclen) {
+                buf[nb++] = ' ';
+                if (funclen > sizeof(buf) - nb - 1)
+                        funclen = sizeof(buf) - nb - 1;
+                memcpy(buf + nb, func, funclen);
+                nb += funclen;
+        }
+        buf[nb++] = '\n';
+
+        mb.ptr = buf;
+        mb.size = nb;
+        if (ecb->outf(ecb->priv, &mb, 1) < 0)
+                return -1;
+
+        return 0;
+}
+
+int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,
+                int line1, int count1, int line2, int count2)
+{
+        /*
+         * This probably does not work outside Git, since
+         * we have a very simple mmfile structure.
+         *
+         * Note: ideally, we would reuse the prepared environment, but
+         * the libxdiff interface does not (yet) allow for diffing only
+         * ranges of lines instead of the whole files.
+         */
+        mmfile_t subfile1, subfile2;
+        xdfenv_t env;
+
+        subfile1.ptr = (char *)diff_env->xdf1.recs[line1 - 1]->ptr;
+        subfile1.size = diff_env->xdf1.recs[line1 + count1 - 2]->ptr +
+                diff_env->xdf1.recs[line1 + count1 - 2]->size - subfile1.ptr;
+        subfile2.ptr = (char *)diff_env->xdf2.recs[line2 - 1]->ptr;
+        subfile2.size = diff_env->xdf2.recs[line2 + count2 - 2]->ptr +
+                diff_env->xdf2.recs[line2 + count2 - 2]->size - subfile2.ptr;
+        if (xdl_do_diff(&subfile1, &subfile2, xpp, &env) < 0)
+                return -1;
+
+        memcpy(diff_env->xdf1.rchg + line1 - 1, env.xdf1.rchg, count1);
+        memcpy(diff_env->xdf2.rchg + line2 - 1, env.xdf2.rchg, count2);
+
+        xdl_free_env(&env);
+
+        return 0;
+}