Add libxdiff library

xdiff/xutils.c

Index: xdiff/xutils.c
diff --git a/xdiff/xutils.c b/xdiff/xutils.c
new file mode 100644
index 0000000000000000000000000000000000000000..62cb23dfd37743e4985655998ccabd56db160233
--- /dev/null
+++ b/xdiff/xutils.c
@@ -0,0 +1,495 @@
+/*
+ *  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;
+}