diff.c 75.6 KB
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/*
 * Copyright (C) 2005 Junio C Hamano
 */
#include "cache.h"
#include "quote.h"
#include "diff.h"
#include "diffcore.h"
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#include "delta.h"
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#include "xdiff-interface.h"
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#include "color.h"
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#include "attr.h"
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#ifdef NO_FAST_WORKING_DIRECTORY
#define FAST_WORKING_DIRECTORY 0
#else
#define FAST_WORKING_DIRECTORY 1
#endif

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static int diff_detect_rename_default;
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static int diff_rename_limit_default = -1;
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static int diff_use_color_default;
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static char diff_colors[][COLOR_MAXLEN] = {
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	"\033[m",	/* reset */
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	"",		/* PLAIN (normal) */
	"\033[1m",	/* METAINFO (bold) */
	"\033[36m",	/* FRAGINFO (cyan) */
	"\033[31m",	/* OLD (red) */
	"\033[32m",	/* NEW (green) */
	"\033[33m",	/* COMMIT (yellow) */
	"\033[41m",	/* WHITESPACE (red background) */
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};

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static int parse_diff_color_slot(const char *var, int ofs)
{
	if (!strcasecmp(var+ofs, "plain"))
		return DIFF_PLAIN;
	if (!strcasecmp(var+ofs, "meta"))
		return DIFF_METAINFO;
	if (!strcasecmp(var+ofs, "frag"))
		return DIFF_FRAGINFO;
	if (!strcasecmp(var+ofs, "old"))
		return DIFF_FILE_OLD;
	if (!strcasecmp(var+ofs, "new"))
		return DIFF_FILE_NEW;
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	if (!strcasecmp(var+ofs, "commit"))
		return DIFF_COMMIT;
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	if (!strcasecmp(var+ofs, "whitespace"))
		return DIFF_WHITESPACE;
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	die("bad config variable '%s'", var);
}

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static struct ll_diff_driver {
	const char *name;
	struct ll_diff_driver *next;
	char *cmd;
} *user_diff, **user_diff_tail;

/*
 * Currently there is only "diff.<drivername>.command" variable;
 * because there are "diff.color.<slot>" variables, we are parsing
 * this in a bit convoluted way to allow low level diff driver
 * called "color".
 */
static int parse_lldiff_command(const char *var, const char *ep, const char *value)
{
	const char *name;
	int namelen;
	struct ll_diff_driver *drv;

	name = var + 5;
	namelen = ep - name;
	for (drv = user_diff; drv; drv = drv->next)
		if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
			break;
	if (!drv) {
		char *namebuf;
		drv = xcalloc(1, sizeof(struct ll_diff_driver));
		namebuf = xmalloc(namelen + 1);
		memcpy(namebuf, name, namelen);
		namebuf[namelen] = 0;
		drv->name = namebuf;
		drv->next = NULL;
		if (!user_diff_tail)
			user_diff_tail = &user_diff;
		*user_diff_tail = drv;
		user_diff_tail = &(drv->next);
	}

	if (!value)
		return error("%s: lacks value", var);
	drv->cmd = strdup(value);
	return 0;
}

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/*
 * These are to give UI layer defaults.
 * The core-level commands such as git-diff-files should
 * never be affected by the setting of diff.renames
 * the user happens to have in the configuration file.
 */
int git_diff_ui_config(const char *var, const char *value)
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{
	if (!strcmp(var, "diff.renamelimit")) {
		diff_rename_limit_default = git_config_int(var, value);
		return 0;
	}
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	if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
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		diff_use_color_default = git_config_colorbool(var, value);
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		return 0;
	}
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	if (!strcmp(var, "diff.renames")) {
		if (!value)
			diff_detect_rename_default = DIFF_DETECT_RENAME;
		else if (!strcasecmp(value, "copies") ||
			 !strcasecmp(value, "copy"))
			diff_detect_rename_default = DIFF_DETECT_COPY;
		else if (git_config_bool(var,value))
			diff_detect_rename_default = DIFF_DETECT_RENAME;
		return 0;
	}
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	if (!prefixcmp(var, "diff.")) {
		const char *ep = strrchr(var, '.');

		if (ep != var + 4 && !strcmp(ep, ".command"))
			return parse_lldiff_command(var, ep, value);
	}
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	if (!prefixcmp(var, "diff.color.") || !prefixcmp(var, "color.diff.")) {
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		int slot = parse_diff_color_slot(var, 11);
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		color_parse(value, var, diff_colors[slot]);
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		return 0;
	}
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	return git_default_config(var, value);
}

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static char *quote_one(const char *str)
{
	int needlen;
	char *xp;

	if (!str)
		return NULL;
	needlen = quote_c_style(str, NULL, NULL, 0);
	if (!needlen)
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		return xstrdup(str);
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	xp = xmalloc(needlen + 1);
	quote_c_style(str, xp, NULL, 0);
	return xp;
}

static char *quote_two(const char *one, const char *two)
{
	int need_one = quote_c_style(one, NULL, NULL, 1);
	int need_two = quote_c_style(two, NULL, NULL, 1);
	char *xp;

	if (need_one + need_two) {
		if (!need_one) need_one = strlen(one);
		if (!need_two) need_one = strlen(two);

		xp = xmalloc(need_one + need_two + 3);
		xp[0] = '"';
		quote_c_style(one, xp + 1, NULL, 1);
		quote_c_style(two, xp + need_one + 1, NULL, 1);
		strcpy(xp + need_one + need_two + 1, "\"");
		return xp;
	}
	need_one = strlen(one);
	need_two = strlen(two);
	xp = xmalloc(need_one + need_two + 1);
	strcpy(xp, one);
	strcpy(xp + need_one, two);
	return xp;
}

static const char *external_diff(void)
{
	static const char *external_diff_cmd = NULL;
	static int done_preparing = 0;

	if (done_preparing)
		return external_diff_cmd;
	external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
	done_preparing = 1;
	return external_diff_cmd;
}

static struct diff_tempfile {
	const char *name; /* filename external diff should read from */
	char hex[41];
	char mode[10];
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	char tmp_path[PATH_MAX];
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} diff_temp[2];

static int count_lines(const char *data, int size)
{
	int count, ch, completely_empty = 1, nl_just_seen = 0;
	count = 0;
	while (0 < size--) {
		ch = *data++;
		if (ch == '\n') {
			count++;
			nl_just_seen = 1;
			completely_empty = 0;
		}
		else {
			nl_just_seen = 0;
			completely_empty = 0;
		}
	}
	if (completely_empty)
		return 0;
	if (!nl_just_seen)
		count++; /* no trailing newline */
	return count;
}

static void print_line_count(int count)
{
	switch (count) {
	case 0:
		printf("0,0");
		break;
	case 1:
		printf("1");
		break;
	default:
		printf("1,%d", count);
		break;
	}
}

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static void copy_file(int prefix, const char *data, int size,
		const char *set, const char *reset)
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{
	int ch, nl_just_seen = 1;
	while (0 < size--) {
		ch = *data++;
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		if (nl_just_seen) {
			fputs(set, stdout);
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			putchar(prefix);
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		}
		if (ch == '\n') {
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			nl_just_seen = 1;
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			fputs(reset, stdout);
		} else
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			nl_just_seen = 0;
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		putchar(ch);
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	}
	if (!nl_just_seen)
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		printf("%s\n\\ No newline at end of file\n", reset);
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}

static void emit_rewrite_diff(const char *name_a,
			      const char *name_b,
			      struct diff_filespec *one,
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			      struct diff_filespec *two,
			      int color_diff)
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{
	int lc_a, lc_b;
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	const char *name_a_tab, *name_b_tab;
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	const char *metainfo = diff_get_color(color_diff, DIFF_METAINFO);
	const char *fraginfo = diff_get_color(color_diff, DIFF_FRAGINFO);
	const char *old = diff_get_color(color_diff, DIFF_FILE_OLD);
	const char *new = diff_get_color(color_diff, DIFF_FILE_NEW);
	const char *reset = diff_get_color(color_diff, DIFF_RESET);
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	name_a += (*name_a == '/');
	name_b += (*name_b == '/');
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	name_a_tab = strchr(name_a, ' ') ? "\t" : "";
	name_b_tab = strchr(name_b, ' ') ? "\t" : "";

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	diff_populate_filespec(one, 0);
	diff_populate_filespec(two, 0);
	lc_a = count_lines(one->data, one->size);
	lc_b = count_lines(two->data, two->size);
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	printf("%s--- a/%s%s%s\n%s+++ b/%s%s%s\n%[email protected]@ -",
	       metainfo, name_a, name_a_tab, reset,
	       metainfo, name_b, name_b_tab, reset, fraginfo);
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	print_line_count(lc_a);
	printf(" +");
	print_line_count(lc_b);
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	printf(" @@%s\n", reset);
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	if (lc_a)
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		copy_file('-', one->data, one->size, old, reset);
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	if (lc_b)
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		copy_file('+', two->data, two->size, new, reset);
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}

static int fill_mmfile(mmfile_t *mf, struct diff_filespec *one)
{
	if (!DIFF_FILE_VALID(one)) {
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		mf->ptr = (char *)""; /* does not matter */
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		mf->size = 0;
		return 0;
	}
	else if (diff_populate_filespec(one, 0))
		return -1;
	mf->ptr = one->data;
	mf->size = one->size;
	return 0;
}

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struct diff_words_buffer {
	mmfile_t text;
	long alloc;
	long current; /* output pointer */
	int suppressed_newline;
};

static void diff_words_append(char *line, unsigned long len,
		struct diff_words_buffer *buffer)
{
	if (buffer->text.size + len > buffer->alloc) {
		buffer->alloc = (buffer->text.size + len) * 3 / 2;
		buffer->text.ptr = xrealloc(buffer->text.ptr, buffer->alloc);
	}
	line++;
	len--;
	memcpy(buffer->text.ptr + buffer->text.size, line, len);
	buffer->text.size += len;
}

struct diff_words_data {
	struct xdiff_emit_state xm;
	struct diff_words_buffer minus, plus;
};

static void print_word(struct diff_words_buffer *buffer, int len, int color,
		int suppress_newline)
{
	const char *ptr;
	int eol = 0;

	if (len == 0)
		return;

	ptr  = buffer->text.ptr + buffer->current;
	buffer->current += len;

	if (ptr[len - 1] == '\n') {
		eol = 1;
		len--;
	}

	fputs(diff_get_color(1, color), stdout);
	fwrite(ptr, len, 1, stdout);
	fputs(diff_get_color(1, DIFF_RESET), stdout);

	if (eol) {
		if (suppress_newline)
			buffer->suppressed_newline = 1;
		else
			putchar('\n');
	}
}

static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
{
	struct diff_words_data *diff_words = priv;

	if (diff_words->minus.suppressed_newline) {
		if (line[0] != '+')
			putchar('\n');
		diff_words->minus.suppressed_newline = 0;
	}

	len--;
	switch (line[0]) {
		case '-':
			print_word(&diff_words->minus, len, DIFF_FILE_OLD, 1);
			break;
		case '+':
			print_word(&diff_words->plus, len, DIFF_FILE_NEW, 0);
			break;
		case ' ':
			print_word(&diff_words->plus, len, DIFF_PLAIN, 0);
			diff_words->minus.current += len;
			break;
	}
}

/* this executes the word diff on the accumulated buffers */
static void diff_words_show(struct diff_words_data *diff_words)
{
	xpparam_t xpp;
	xdemitconf_t xecfg;
	xdemitcb_t ecb;
	mmfile_t minus, plus;
	int i;

	minus.size = diff_words->minus.text.size;
	minus.ptr = xmalloc(minus.size);
	memcpy(minus.ptr, diff_words->minus.text.ptr, minus.size);
	for (i = 0; i < minus.size; i++)
		if (isspace(minus.ptr[i]))
			minus.ptr[i] = '\n';
	diff_words->minus.current = 0;

	plus.size = diff_words->plus.text.size;
	plus.ptr = xmalloc(plus.size);
	memcpy(plus.ptr, diff_words->plus.text.ptr, plus.size);
	for (i = 0; i < plus.size; i++)
		if (isspace(plus.ptr[i]))
			plus.ptr[i] = '\n';
	diff_words->plus.current = 0;

	xpp.flags = XDF_NEED_MINIMAL;
	xecfg.ctxlen = diff_words->minus.alloc + diff_words->plus.alloc;
	xecfg.flags = 0;
	ecb.outf = xdiff_outf;
	ecb.priv = diff_words;
	diff_words->xm.consume = fn_out_diff_words_aux;
	xdl_diff(&minus, &plus, &xpp, &xecfg, &ecb);

	free(minus.ptr);
	free(plus.ptr);
	diff_words->minus.text.size = diff_words->plus.text.size = 0;

	if (diff_words->minus.suppressed_newline) {
		putchar('\n');
		diff_words->minus.suppressed_newline = 0;
	}
}

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struct emit_callback {
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	struct xdiff_emit_state xm;
	int nparents, color_diff;
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	const char **label_path;
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	struct diff_words_data *diff_words;
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	int *found_changesp;
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};

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static void free_diff_words_data(struct emit_callback *ecbdata)
{
	if (ecbdata->diff_words) {
		/* flush buffers */
		if (ecbdata->diff_words->minus.text.size ||
				ecbdata->diff_words->plus.text.size)
			diff_words_show(ecbdata->diff_words);

		if (ecbdata->diff_words->minus.text.ptr)
			free (ecbdata->diff_words->minus.text.ptr);
		if (ecbdata->diff_words->plus.text.ptr)
			free (ecbdata->diff_words->plus.text.ptr);
		free(ecbdata->diff_words);
		ecbdata->diff_words = NULL;
	}
}

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const char *diff_get_color(int diff_use_color, enum color_diff ix)
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{
	if (diff_use_color)
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		return diff_colors[ix];
	return "";
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}

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static void emit_line(const char *set, const char *reset, const char *line, int len)
{
	if (len > 0 && line[len-1] == '\n')
		len--;
	fputs(set, stdout);
	fwrite(line, len, 1, stdout);
	puts(reset);
}

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static void emit_line_with_ws(int nparents,
		const char *set, const char *reset, const char *ws,
		const char *line, int len)
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{
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	int col0 = nparents;
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	int last_tab_in_indent = -1;
	int last_space_in_indent = -1;
	int i;
	int tail = len;
	int need_highlight_leading_space = 0;
	/* The line is a newly added line.  Does it have funny leading
	 * whitespaces?  In indent, SP should never precede a TAB.
	 */
	for (i = col0; i < len; i++) {
		if (line[i] == '\t') {
			last_tab_in_indent = i;
			if (0 <= last_space_in_indent)
				need_highlight_leading_space = 1;
		}
		else if (line[i] == ' ')
			last_space_in_indent = i;
		else
			break;
	}
	fputs(set, stdout);
	fwrite(line, col0, 1, stdout);
	fputs(reset, stdout);
	if (((i == len) || line[i] == '\n') && i != col0) {
		/* The whole line was indent */
		emit_line(ws, reset, line + col0, len - col0);
		return;
	}
	i = col0;
	if (need_highlight_leading_space) {
		while (i < last_tab_in_indent) {
			if (line[i] == ' ') {
				fputs(ws, stdout);
				putchar(' ');
				fputs(reset, stdout);
			}
			else
				putchar(line[i]);
			i++;
		}
	}
	tail = len - 1;
	if (line[tail] == '\n' && i < tail)
		tail--;
	while (i < tail) {
		if (!isspace(line[tail]))
			break;
		tail--;
	}
	if ((i < tail && line[tail + 1] != '\n')) {
		/* This has whitespace between tail+1..len */
		fputs(set, stdout);
		fwrite(line + i, tail - i + 1, 1, stdout);
		fputs(reset, stdout);
		emit_line(ws, reset, line + tail + 1, len - tail - 1);
	}
	else
		emit_line(set, reset, line + i, len - i);
}

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static void emit_add_line(const char *reset, struct emit_callback *ecbdata, const char *line, int len)
{
	const char *ws = diff_get_color(ecbdata->color_diff, DIFF_WHITESPACE);
	const char *set = diff_get_color(ecbdata->color_diff, DIFF_FILE_NEW);

	if (!*ws)
		emit_line(set, reset, line, len);
	else
		emit_line_with_ws(ecbdata->nparents, set, reset, ws,
				line, len);
}

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static void fn_out_consume(void *priv, char *line, unsigned long len)
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{
	int i;
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	int color;
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	struct emit_callback *ecbdata = priv;
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	const char *set = diff_get_color(ecbdata->color_diff, DIFF_METAINFO);
	const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
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	*(ecbdata->found_changesp) = 1;

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	if (ecbdata->label_path[0]) {
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		const char *name_a_tab, *name_b_tab;

		name_a_tab = strchr(ecbdata->label_path[0], ' ') ? "\t" : "";
		name_b_tab = strchr(ecbdata->label_path[1], ' ') ? "\t" : "";

		printf("%s--- %s%s%s\n",
		       set, ecbdata->label_path[0], reset, name_a_tab);
		printf("%s+++ %s%s%s\n",
		       set, ecbdata->label_path[1], reset, name_b_tab);
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		ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
	}
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	/* This is not really necessary for now because
	 * this codepath only deals with two-way diffs.
	 */
	for (i = 0; i < len && line[i] == '@'; i++)
		;
	if (2 <= i && i < len && line[i] == ' ') {
		ecbdata->nparents = i - 1;
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		emit_line(diff_get_color(ecbdata->color_diff, DIFF_FRAGINFO),
			  reset, line, len);
		return;
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	}
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	if (len < ecbdata->nparents) {
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		set = reset;
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		emit_line(reset, reset, line, len);
		return;
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	}
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	color = DIFF_PLAIN;
	if (ecbdata->diff_words && ecbdata->nparents != 1)
		/* fall back to normal diff */
		free_diff_words_data(ecbdata);
	if (ecbdata->diff_words) {
		if (line[0] == '-') {
			diff_words_append(line, len,
					  &ecbdata->diff_words->minus);
			return;
		} else if (line[0] == '+') {
			diff_words_append(line, len,
					  &ecbdata->diff_words->plus);
			return;
		}
		if (ecbdata->diff_words->minus.text.size ||
		    ecbdata->diff_words->plus.text.size)
			diff_words_show(ecbdata->diff_words);
		line++;
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		len--;
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		emit_line(set, reset, line, len);
		return;
	}
	for (i = 0; i < ecbdata->nparents && len; i++) {
		if (line[i] == '-')
			color = DIFF_FILE_OLD;
		else if (line[i] == '+')
			color = DIFF_FILE_NEW;
	}

	if (color != DIFF_FILE_NEW) {
		emit_line(diff_get_color(ecbdata->color_diff, color),
			  reset, line, len);
		return;
	}
	emit_add_line(reset, ecbdata, line, len);
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}

static char *pprint_rename(const char *a, const char *b)
{
	const char *old = a;
	const char *new = b;
	char *name = NULL;
	int pfx_length, sfx_length;
	int len_a = strlen(a);
	int len_b = strlen(b);
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	int qlen_a = quote_c_style(a, NULL, NULL, 0);
	int qlen_b = quote_c_style(b, NULL, NULL, 0);

	if (qlen_a || qlen_b) {
		if (qlen_a) len_a = qlen_a;
		if (qlen_b) len_b = qlen_b;
		name = xmalloc( len_a + len_b + 5 );
		if (qlen_a)
			quote_c_style(a, name, NULL, 0);
		else
			memcpy(name, a, len_a);
		memcpy(name + len_a, " => ", 4);
		if (qlen_b)
			quote_c_style(b, name + len_a + 4, NULL, 0);
		else
			memcpy(name + len_a + 4, b, len_b + 1);
		return name;
	}
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	/* Find common prefix */
	pfx_length = 0;
	while (*old && *new && *old == *new) {
		if (*old == '/')
			pfx_length = old - a + 1;
		old++;
		new++;
	}

	/* Find common suffix */
	old = a + len_a;
	new = b + len_b;
	sfx_length = 0;
	while (a <= old && b <= new && *old == *new) {
		if (*old == '/')
			sfx_length = len_a - (old - a);
		old--;
		new--;
	}

	/*
	 * pfx{mid-a => mid-b}sfx
	 * {pfx-a => pfx-b}sfx
	 * pfx{sfx-a => sfx-b}
	 * name-a => name-b
	 */
	if (pfx_length + sfx_length) {
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		int a_midlen = len_a - pfx_length - sfx_length;
		int b_midlen = len_b - pfx_length - sfx_length;
		if (a_midlen < 0) a_midlen = 0;
		if (b_midlen < 0) b_midlen = 0;

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		name = xmalloc(pfx_length + a_midlen + b_midlen + sfx_length + 7);
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		sprintf(name, "%.*s{%.*s => %.*s}%s",
			pfx_length, a,
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			a_midlen, a + pfx_length,
			b_midlen, b + pfx_length,
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			a + len_a - sfx_length);
	}
	else {
		name = xmalloc(len_a + len_b + 5);
		sprintf(name, "%s => %s", a, b);
	}
	return name;
}

struct diffstat_t {
	struct xdiff_emit_state xm;

	int nr;
	int alloc;
	struct diffstat_file {
		char *name;
		unsigned is_unmerged:1;
		unsigned is_binary:1;
		unsigned is_renamed:1;
		unsigned int added, deleted;
	} **files;
};

static struct diffstat_file *diffstat_add(struct diffstat_t *diffstat,
					  const char *name_a,
					  const char *name_b)
{
	struct diffstat_file *x;
	x = xcalloc(sizeof (*x), 1);
	if (diffstat->nr == diffstat->alloc) {
		diffstat->alloc = alloc_nr(diffstat->alloc);
		diffstat->files = xrealloc(diffstat->files,
				diffstat->alloc * sizeof(x));
	}
	diffstat->files[diffstat->nr++] = x;
	if (name_b) {
		x->name = pprint_rename(name_a, name_b);
		x->is_renamed = 1;
	}
	else
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		x->name = xstrdup(name_a);
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	return x;
}

static void diffstat_consume(void *priv, char *line, unsigned long len)
{
	struct diffstat_t *diffstat = priv;
	struct diffstat_file *x = diffstat->files[diffstat->nr - 1];

	if (line[0] == '+')
		x->added++;
	else if (line[0] == '-')
		x->deleted++;
}

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const char mime_boundary_leader[] = "------------";
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static int scale_linear(int it, int width, int max_change)
{
	/*
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	 * make sure that at least one '-' is printed if there were deletions,
	 * and likewise for '+'.
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	 */
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	if (max_change < 2)
		return it;
	return ((it - 1) * (width - 1) + max_change - 1) / (max_change - 1);
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}

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static void show_name(const char *prefix, const char *name, int len,
		      const char *reset, const char *set)
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{
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	printf(" %s%s%-*s%s |", set, prefix, len, name, reset);
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}

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static void show_graph(char ch, int cnt, const char *set, const char *reset)
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{
	if (cnt <= 0)
		return;
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	printf("%s", set);
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	while (cnt--)
		putchar(ch);
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	printf("%s", reset);
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}

static void show_stats(struct diffstat_t* data, struct diff_options *options)
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{
	int i, len, add, del, total, adds = 0, dels = 0;
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	int max_change = 0, max_len = 0;
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	int total_files = data->nr;
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	int width, name_width;
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	const char *reset, *set, *add_c, *del_c;
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	if (data->nr == 0)
		return;

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	width = options->stat_width ? options->stat_width : 80;
	name_width = options->stat_name_width ? options->stat_name_width : 50;

	/* Sanity: give at least 5 columns to the graph,
	 * but leave at least 10 columns for the name.
	 */
	if (width < name_width + 15) {
		if (name_width <= 25)
			width = name_width + 15;
		else
			name_width = width - 15;
	}

	/* Find the longest filename and max number of changes */
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	reset = diff_get_color(options->color_diff, DIFF_RESET);
	set = diff_get_color(options->color_diff, DIFF_PLAIN);
	add_c = diff_get_color(options->color_diff, DIFF_FILE_NEW);
	del_c = diff_get_color(options->color_diff, DIFF_FILE_OLD);

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	for (i = 0; i < data->nr; i++) {
		struct diffstat_file *file = data->files[i];
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		int change = file->added + file->deleted;

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		if (!file->is_renamed) {  /* renames are already quoted by pprint_rename */
			len = quote_c_style(file->name, NULL, NULL, 0);
			if (len) {
				char *qname = xmalloc(len + 1);
				quote_c_style(file->name, qname, NULL, 0);
				free(file->name);
				file->name = qname;
			}
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		}
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		len = strlen(file->name);
		if (max_len < len)
			max_len = len;

		if (file->is_binary || file->is_unmerged)
			continue;
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		if (max_change < change)
			max_change = change;
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	}

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	/* Compute the width of the graph part;
	 * 10 is for one blank at the beginning of the line plus
	 * " | count " between the name and the graph.
	 *
	 * From here on, name_width is the width of the name area,
	 * and width is the width of the graph area.
	 */
	name_width = (name_width < max_len) ? name_width : max_len;
	if (width < (name_width + 10) + max_change)
		width = width - (name_width + 10);
	else
		width = max_change;

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	for (i = 0; i < data->nr; i++) {
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		const char *prefix = "";
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		char *name = data->files[i]->name;
		int added = data->files[i]->added;
		int deleted = data->files[i]->deleted;
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		int name_len;
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		/*
		 * "scale" the filename
		 */
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		len = name_width;
		name_len = strlen(name);
		if (name_width < name_len) {
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			char *slash;
			prefix = "...";
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			len -= 3;
			name += name_len - len;
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			slash = strchr(name, '/');
			if (slash)
				name = slash;
		}

		if (data->files[i]->is_binary) {
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			show_name(prefix, name, len, reset, set);
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			printf("  Bin ");
			printf("%s%d%s", del_c, deleted, reset);
			printf(" -> ");
			printf("%s%d%s", add_c, added, reset);
			printf(" bytes");
			printf("\n");
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			goto free_diffstat_file;
		}
		else if (data->files[i]->is_unmerged) {
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			show_name(prefix, name, len, reset, set);
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			printf("  Unmerged\n");
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			goto free_diffstat_file;
		}
		else if (!data->files[i]->is_renamed &&
			 (added + deleted == 0)) {
			total_files--;
			goto free_diffstat_file;
		}

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		/*
		 * scale the add/delete
		 */
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		add = added;
		del = deleted;
		total = add + del;
		adds += add;
		dels += del;

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		if (width <= max_change) {
			add = scale_linear(add, width, max_change);
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			del = scale_linear(del, width, max_change);
			total = add + del;
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		}
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		show_name(prefix, name, len, reset, set);
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		printf("%5d ", added + deleted);
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		show_graph('+', add, add_c, reset);
		show_graph('-', del, del_c, reset);
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		putchar('\n');
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	free_diffstat_file:
		free(data->files[i]->name);
		free(data->files[i]);
	}
	free(data->files);
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	printf("%s %d files changed, %d insertions(+), %d deletions(-)%s\n",
	       set, total_files, adds, dels, reset);
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}

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static void show_shortstats(struct diffstat_t* data)
{
	int i, adds = 0, dels = 0, total_files = data->nr;

	if (data->nr == 0)
		return;

	for (i = 0; i < data->nr; i++) {
		if (!data->files[i]->is_binary &&
		    !data->files[i]->is_unmerged) {
			int added = data->files[i]->added;
			int deleted= data->files[i]->deleted;
			if (!data->files[i]->is_renamed &&
			    (added + deleted == 0)) {
				total_files--;
			} else {
				adds += added;
				dels += deleted;
			}
		}
		free(data->files[i]->name);
		free(data->files[i]);
	}
	free(data->files);

	printf(" %d files changed, %d insertions(+), %d deletions(-)\n",
	       total_files, adds, dels);
}

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static void show_numstat(struct diffstat_t* data, struct diff_options *options)
{
	int i;

	for (i = 0; i < data->nr; i++) {
		struct diffstat_file *file = data->files[i];

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		if (file->is_binary)
			printf("-\t-\t");
		else
			printf("%d\t%d\t", file->added, file->deleted);
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		if (options->line_termination && !file->is_renamed &&
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		    quote_c_style(file->name, NULL, NULL, 0))
			quote_c_style(file->name, NULL, stdout, 0);
		else
			fputs(file->name, stdout);
		putchar(options->line_termination);
	}
}

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struct checkdiff_t {
	struct xdiff_emit_state xm;
	const char *filename;
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	int lineno, color_diff;
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};

static void checkdiff_consume(void *priv, char *line, unsigned long len)
{
	struct checkdiff_t *data = priv;
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	const char *ws = diff_get_color(data->color_diff, DIFF_WHITESPACE);
	const char *reset = diff_get_color(data->color_diff, DIFF_RESET);
	const char *set = diff_get_color(data->color_diff, DIFF_FILE_NEW);
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	if (line[0] == '+') {
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		int i, spaces = 0, space_before_tab = 0, white_space_at_end = 0;
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		/* check space before tab */
		for (i = 1; i < len && (line[i] == ' ' || line[i] == '\t'); i++)
			if (line[i] == ' ')
				spaces++;
		if (line[i - 1] == '\t' && spaces)
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			space_before_tab = 1;
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		/* check white space at line end */
		if (line[len - 1] == '\n')
			len--;
		if (isspace(line[len - 1]))
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			white_space_at_end = 1;

		if (space_before_tab || white_space_at_end) {
			printf("%s:%d: %s", data->filename, data->lineno, ws);
			if (space_before_tab) {
				printf("space before tab");
				if (white_space_at_end)
					putchar(',');
			}
			if (white_space_at_end)
				printf("white space at end");
			printf(":%s ", reset);
			emit_line_with_ws(1, set, reset, ws, line, len);
		}
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		data->lineno++;
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	} else if (line[0] == ' ')
		data->lineno++;
	else if (line[0] == '@') {
		char *plus = strchr(line, '+');
		if (plus)
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			data->lineno = strtol(plus, NULL, 10);
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		else
			die("invalid diff");
	}
}

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static unsigned char *deflate_it(char *data,
				 unsigned long size,
				 unsigned long *result_size)
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{
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	int bound;
	unsigned char *deflated;
	z_stream stream;

	memset(&stream, 0, sizeof(stream));
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	deflateInit(&stream, zlib_compression_level);
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	bound = deflateBound(&stream, size);
	deflated = xmalloc(bound);
	stream.next_out = deflated;
	stream.avail_out = bound;

	stream.next_in = (unsigned char *)data;
	stream.avail_in = size;
	while (deflate(&stream, Z_FINISH) == Z_OK)
		; /* nothing */
	deflateEnd(&stream);
	*result_size = stream.total_out;
	return deflated;
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}

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static void emit_binary_diff_body(mmfile_t *one, mmfile_t *two)
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{
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	void *cp;
	void *delta;
	void *deflated;
	void *data;
	unsigned long orig_size;
	unsigned long delta_size;
	unsigned long deflate_size;
	unsigned long data_size;
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	/* We could do deflated delta, or we could do just deflated two,
	 * whichever is smaller.
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	 */
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	delta = NULL;
	deflated = deflate_it(two->ptr, two->size, &deflate_size);
	if (one->size && two->size) {
		delta = diff_delta(one->ptr, one->size,
				   two->ptr, two->size,
				   &delta_size, deflate_size);
		if (delta) {
			void *to_free = delta;
			orig_size = delta_size;
			delta = deflate_it(delta, delta_size, &delta_size);
			free(to_free);
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		}
	}

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	if (delta && delta_size < deflate_size) {
		printf("delta %lu\n", orig_size);
		free(deflated);
		data = delta;
		data_size = delta_size;
	}
	else {
		printf("literal %lu\n", two->size);
		free(delta);
		data = deflated;
		data_size = deflate_size;
	}
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	/* emit data encoded in base85 */
	cp = data;
	while (data_size) {
		int bytes = (52 < data_size) ? 52 : data_size;
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		char line[70];
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		data_size -= bytes;
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		if (bytes <= 26)
			line[0] = bytes + 'A' - 1;
		else
			line[0] = bytes - 26 + 'a' - 1;
		encode_85(line + 1, cp, bytes);
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		cp = (char *) cp + bytes;
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		puts(line);
	}
	printf("\n");
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	free(data);
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}

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static void emit_binary_diff(mmfile_t *one, mmfile_t *two)
{
	printf("GIT binary patch\n");
	emit_binary_diff_body(one, two);
	emit_binary_diff_body(two, one);
}

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static void setup_diff_attr_check(struct git_attr_check *check)
{
	static struct git_attr *attr_diff;

	if (!attr_diff)
		attr_diff = git_attr("diff", 4);
	check->attr = attr_diff;
}

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#define FIRST_FEW_BYTES 8000
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static int file_is_binary(struct diff_filespec *one)
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{
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	unsigned long sz;
	struct git_attr_check attr_diff_check;

	setup_diff_attr_check(&attr_diff_check);
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	if (!git_checkattr(one->path, 1, &attr_diff_check)) {
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		const char *value = attr_diff_check.value;
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		if (ATTR_TRUE(value))
			return 0;
		else if (ATTR_FALSE(value))
			return 1;
	}
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	if (!one->data) {
		if (!DIFF_FILE_VALID(one))
			return 0;
		diff_populate_filespec(one, 0);
	}
	sz = one->size;
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	if (FIRST_FEW_BYTES < sz)
		sz = FIRST_FEW_BYTES;
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	return !!memchr(one->data, 0, sz);
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}

static void builtin_diff(const char *name_a,
			 const char *name_b,
			 struct diff_filespec *one,
			 struct diff_filespec *two,
			 const char *xfrm_msg,
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			 struct diff_options *o,
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			 int complete_rewrite)
{
	mmfile_t mf1, mf2;
	const char *lbl[2];
	char *a_one, *b_two;
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	const char *set = diff_get_color(o->color_diff, DIFF_METAINFO);
	const char *reset = diff_get_color(o->color_diff, DIFF_RESET);
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	a_one = quote_two("a/", name_a + (*name_a == '/'));
	b_two = quote_two("b/", name_b + (*name_b == '/'));
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	lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
	lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
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	printf("%sdiff --git %s %s%s\n", set, a_one, b_two, reset);
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	if (lbl[0][0] == '/') {
		/* /dev/null */
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		printf("%snew file mode %06o%s\n", set, two->mode, reset);
		if (xfrm_msg && xfrm_msg[0])
			printf("%s%s%s\n", set, xfrm_msg, reset);
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	}
	else if (lbl[1][0] == '/') {
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		printf("%sdeleted file mode %06o%s\n", set, one->mode, reset);
		if (xfrm_msg && xfrm_msg[0])
			printf("%s%s%s\n", set, xfrm_msg, reset);
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	}
	else {
		if (one->mode != two->mode) {
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			printf("%sold mode %06o%s\n", set, one->mode, reset);
			printf("%snew mode %06o%s\n", set, two->mode, reset);
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		}
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		if (xfrm_msg && xfrm_msg[0])
			printf("%s%s%s\n", set, xfrm_msg, reset);
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		/*
		 * we do not run diff between different kind
		 * of objects.
		 */
		if ((one->mode ^ two->mode) & S_IFMT)
			goto free_ab_and_return;
		if (complete_rewrite) {
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			emit_rewrite_diff(name_a, name_b, one, two,
					o->color_diff);
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			o->found_changes = 1;
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			goto free_ab_and_return;
		}
	}

	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
		die("unable to read files to diff");

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	if (!o->text && (file_is_binary(one) || file_is_binary(two))) {
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		/* Quite common confusing case */
		if (mf1.size == mf2.size &&
		    !memcmp(mf1.ptr, mf2.ptr, mf1.size))
			goto free_ab_and_return;
		if (o->binary)
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			emit_binary_diff(&mf1, &mf2);
		else
			printf("Binary files %s and %s differ\n",
			       lbl[0], lbl[1]);
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		o->found_changes = 1;
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	}
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	else {
		/* Crazy xdl interfaces.. */
		const char *diffopts = getenv("GIT_DIFF_OPTS");
		xpparam_t xpp;
		xdemitconf_t xecfg;
		xdemitcb_t ecb;
		struct emit_callback ecbdata;

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		memset(&ecbdata, 0, sizeof(ecbdata));
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		ecbdata.label_path = lbl;
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		ecbdata.color_diff = o->color_diff;
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		ecbdata.found_changesp = &o->found_changes;
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		xpp.flags = XDF_NEED_MINIMAL | o->xdl_opts;
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		xecfg.ctxlen = o->context;
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		xecfg.flags = XDL_EMIT_FUNCNAMES;
		if (!diffopts)
			;
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		else if (!prefixcmp(diffopts, "--unified="))
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			xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
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		else if (!prefixcmp(diffopts, "-u"))
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			xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
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		ecb.outf = xdiff_outf;
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		ecb.priv = &ecbdata;
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		ecbdata.xm.consume = fn_out_consume;
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		if (o->color_diff_words)
			ecbdata.diff_words =
				xcalloc(1, sizeof(struct diff_words_data));
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		xdl_diff(&mf1, &mf2, &xpp, &xecfg, &ecb);
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		if (o->color_diff_words)
			free_diff_words_data(&ecbdata);
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	}

 free_ab_and_return:
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	diff_free_filespec_data(one);
	diff_free_filespec_data(two);
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	free(a_one);
	free(b_two);
	return;
}

static void builtin_diffstat(const char *name_a, const char *name_b,
			     struct diff_filespec *one,
			     struct diff_filespec *two,
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			     struct diffstat_t *diffstat,
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			     struct diff_options *o,
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			     int complete_rewrite)
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{
	mmfile_t mf1, mf2;
	struct diffstat_file *data;

	data = diffstat_add(diffstat, name_a, name_b);

	if (!one || !two) {
		data->is_unmerged = 1;
		return;
	}
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	if (complete_rewrite) {
		diff_populate_filespec(one, 0);
		diff_populate_filespec(two, 0);
		data->deleted = count_lines(one->data, one->size);
		data->added = count_lines(two->data, two->size);
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		goto free_and_return;
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	}
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	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
		die("unable to read files to diff");

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	if (file_is_binary(one) || file_is_binary(two)) {
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		data->is_binary = 1;
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		data->added = mf2.size;
		data->deleted = mf1.size;
	} else {
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		/* Crazy xdl interfaces.. */
		xpparam_t xpp;
		xdemitconf_t xecfg;
		xdemitcb_t ecb;

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		xpp.flags = XDF_NEED_MINIMAL | o->xdl_opts;
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		xecfg.ctxlen = 0;
		xecfg.flags = 0;
		ecb.outf = xdiff_outf;
		ecb.priv = diffstat;
		xdl_diff(&mf1, &mf2, &xpp, &xecfg, &ecb);
	}
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 free_and_return:
	diff_free_filespec_data(one);
	diff_free_filespec_data(two);
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}

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static void builtin_checkdiff(const char *name_a, const char *name_b,
			     struct diff_filespec *one,
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			     struct diff_filespec *two, struct diff_options *o)
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{
	mmfile_t mf1, mf2;
	struct checkdiff_t data;

	if (!two)
		return;

	memset(&data, 0, sizeof(data));
	data.xm.consume = checkdiff_consume;
	data.filename = name_b ? name_b : name_a;
	data.lineno = 0;
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	data.color_diff = o->color_diff;
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	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
		die("unable to read files to diff");

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	if (file_is_binary(two))
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		goto free_and_return;
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	else {
		/* Crazy xdl interfaces.. */
		xpparam_t xpp;
		xdemitconf_t xecfg;
		xdemitcb_t ecb;

		xpp.flags = XDF_NEED_MINIMAL;
		xecfg.ctxlen = 0;
		xecfg.flags = 0;
		ecb.outf = xdiff_outf;
		ecb.priv = &data;
		xdl_diff(&mf1, &mf2, &xpp, &xecfg, &ecb);
	}
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 free_and_return:
	diff_free_filespec_data(one);
	diff_free_filespec_data(two);
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}

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struct diff_filespec *alloc_filespec(const char *path)
{
	int namelen = strlen(path);
	struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);

	memset(spec, 0, sizeof(*spec));
	spec->path = (char *)(spec + 1);
	memcpy(spec->path, path, namelen+1);
	return spec;
}

void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
		   unsigned short mode)
{
	if (mode) {
		spec->mode = canon_mode(mode);
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		hashcpy(spec->sha1, sha1);
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		spec->sha1_valid = !is_null_sha1(sha1);
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	}
}

/*
 * Given a name and sha1 pair, if the dircache tells us the file in
 * the work tree has that object contents, return true, so that
 * prepare_temp_file() does not have to inflate and extract.
 */
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static int reuse_worktree_file(const char *name, const unsigned char *sha1, int want_file)
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{
	struct cache_entry *ce;
	struct stat st;
	int pos, len;

	/* We do not read the cache ourselves here, because the
	 * benchmark with my previous version that always reads cache
	 * shows that it makes things worse for diff-tree comparing
	 * two linux-2.6 kernel trees in an already checked out work
	 * tree.  This is because most diff-tree comparisons deal with
	 * only a small number of files, while reading the cache is
	 * expensive for a large project, and its cost outweighs the
	 * savings we get by not inflating the object to a temporary
	 * file.  Practically, this code only helps when we are used
	 * by diff-cache --cached, which does read the cache before
	 * calling us.
	 */
	if (!active_cache)
		return 0;

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	/* We want to avoid the working directory if our caller
	 * doesn't need the data in a normal file, this system
	 * is rather slow with its stat/open/mmap/close syscalls,
	 * and the object is contained in a pack file.  The pack
	 * is probably already open and will be faster to obtain
	 * the data through than the working directory.  Loose
	 * objects however would tend to be slower as they need
	 * to be individually opened and inflated.
	 */
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	if (!FAST_WORKING_DIRECTORY && !want_file && has_sha1_pack(sha1, NULL))
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		return 0;

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	len = strlen(name);
	pos = cache_name_pos(name, len);
	if (pos < 0)
		return 0;
	ce = active_cache[pos];
	if ((lstat(name, &st) < 0) ||
	    !S_ISREG(st.st_mode) || /* careful! */
	    ce_match_stat(ce, &st, 0) ||
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	    hashcmp(sha1, ce->sha1))
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		return 0;
	/* we return 1 only when we can stat, it is a regular file,
	 * stat information matches, and sha1 recorded in the cache
	 * matches.  I.e. we know the file in the work tree really is
	 * the same as the <name, sha1> pair.
	 */
	return 1;
}

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static int populate_from_stdin(struct diff_filespec *s)
{
#define INCREMENT 1024
	char *buf;
	unsigned long size;
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	ssize_t got;
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	size = 0;
	buf = NULL;
	while (1) {
		buf = xrealloc(buf, size + INCREMENT);
		got = xread(0, buf + size, INCREMENT);
		if (!got)
			break; /* EOF */
		if (got < 0)
			return error("error while reading from stdin %s",
				     strerror(errno));
		size += got;
	}
	s->should_munmap = 0;
	s->data = buf;
	s->size = size;
	s->should_free = 1;
	return 0;
}

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static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
{
	int len;
	char *data = xmalloc(100);
	len = snprintf(data, 100,
		"Subproject commit %s\n", sha1_to_hex(s->sha1));
	s->data = data;
	s->size = len;
	s->should_free = 1;
	if (size_only) {
		s->data = NULL;
		free(data);
	}
	return 0;
}

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/*
 * While doing rename detection and pickaxe operation, we may need to
 * grab the data for the blob (or file) for our own in-core comparison.
 * diff_filespec has data and size fields for this purpose.
 */
int diff_populate_filespec(struct diff_filespec *s, int size_only)
{
	int err = 0;
	if (!DIFF_FILE_VALID(s))
		die("internal error: asking to populate invalid file.");
	if (S_ISDIR(s->mode))
		return -1;

	if (s->data)
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		return 0;
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	if (size_only && 0 < s->size)
		return 0;

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	if (S_ISGITLINK(s->mode))
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		return diff_populate_gitlink(s, size_only);

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	if (!s->sha1_valid ||
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	    reuse_worktree_file(s->path, s->sha1, 0)) {
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		struct stat st;
		int fd;
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		char *buf;
		unsigned long size;

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		if (!strcmp(s->path, "-"))
			return populate_from_stdin(s);

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		if (lstat(s->path, &st) < 0) {
			if (errno == ENOENT) {
			err_empty:
				err = -1;
			empty:
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				s->data = (char *)"";
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				s->size = 0;
				return err;
			}
		}