git/apply.c

/*
 * apply.c
 *
 * Copyright (C) Linus Torvalds, 2005
 *
 * This applies patches on top of some (arbitrary) version of the SCM.
 *
 */

#include "cache.h"
#include "config.h"
#include "object-store.h"
#include "blob.h"
#include "delta.h"
#include "diff.h"
#include "dir.h"
#include "xdiff-interface.h"
#include "ll-merge.h"
#include "lockfile.h"
#include "parse-options.h"
#include "quote.h"
#include "rerere.h"
#include "apply.h"
#include "entry.h"

struct gitdiff_data {
	struct strbuf *root;
	int linenr;
	int p_value;
};

static void git_apply_config(void)
{
	git_config_get_string("apply.whitespace", &apply_default_whitespace);
	git_config_get_string("apply.ignorewhitespace", &apply_default_ignorewhitespace);
	git_config(git_xmerge_config, NULL);
}

static int parse_whitespace_option(struct apply_state *state, const char *option)
{
	if (!option) {
		state->ws_error_action = warn_on_ws_error;
		return 0;
	}
	if (!strcmp(option, "warn")) {
		state->ws_error_action = warn_on_ws_error;
		return 0;
	}
	if (!strcmp(option, "nowarn")) {
		state->ws_error_action = nowarn_ws_error;
		return 0;
	}
	if (!strcmp(option, "error")) {
		state->ws_error_action = die_on_ws_error;
		return 0;
	}
	if (!strcmp(option, "error-all")) {
		state->ws_error_action = die_on_ws_error;
		state->squelch_whitespace_errors = 0;
		return 0;
	}
	if (!strcmp(option, "strip") || !strcmp(option, "fix")) {
		state->ws_error_action = correct_ws_error;
		return 0;
	}
	/*
	 * Please update $__git_whitespacelist in git-completion.bash
	 * when you add new options.
	 */
	return error(_("unrecognized whitespace option '%s'"), option);
}

static int parse_ignorewhitespace_option(struct apply_state *state,
						 const char *option)
{
	if (!option || !strcmp(option, "no") ||
	    !strcmp(option, "false") || !strcmp(option, "never") ||
	    !strcmp(option, "none")) {
		state->ws_ignore_action = ignore_ws_none;
		return 0;
	}
	if (!strcmp(option, "change")) {
		state->ws_ignore_action = ignore_ws_change;
		return 0;
	}
	return error(_("unrecognized whitespace ignore option '%s'"), option);
}

int init_apply_state(struct apply_state *state,
		     struct repository *repo,
		     const char *prefix)
{
	memset(state, 0, sizeof(*state));
	state->prefix = prefix;
	state->repo = repo;
	state->apply = 1;
	state->line_termination = '\n';
	state->p_value = 1;
	state->p_context = UINT_MAX;
	state->squelch_whitespace_errors = 5;
	state->ws_error_action = warn_on_ws_error;
	state->ws_ignore_action = ignore_ws_none;
	state->linenr = 1;
	string_list_init_nodup(&state->fn_table);
	string_list_init_nodup(&state->limit_by_name);
	strset_init(&state->removed_symlinks);
	strset_init(&state->kept_symlinks);
	strbuf_init(&state->root, 0);

	git_apply_config();
	if (apply_default_whitespace && parse_whitespace_option(state, apply_default_whitespace))
		return -1;
	if (apply_default_ignorewhitespace && parse_ignorewhitespace_option(state, apply_default_ignorewhitespace))
		return -1;
	return 0;
}

void clear_apply_state(struct apply_state *state)
{
	string_list_clear(&state->limit_by_name, 0);
	strset_clear(&state->removed_symlinks);
	strset_clear(&state->kept_symlinks);
	strbuf_release(&state->root);

	/* &state->fn_table is cleared at the end of apply_patch() */
}

static void mute_routine(const char *msg, va_list params)
{
	/* do nothing */
}

int check_apply_state(struct apply_state *state, int force_apply)
{
	int is_not_gitdir = !startup_info->have_repository;

	if (state->apply_with_reject && state->threeway)
		return error(_("options '%s' and '%s' cannot be used together"), "--reject", "--3way");
	if (state->threeway) {
		if (is_not_gitdir)
			return error(_("'%s' outside a repository"), "--3way");
		state->check_index = 1;
	}
	if (state->apply_with_reject) {
		state->apply = 1;
		if (state->apply_verbosity == verbosity_normal)
			state->apply_verbosity = verbosity_verbose;
	}
	if (!force_apply && (state->diffstat || state->numstat || state->summary || state->check || state->fake_ancestor))
		state->apply = 0;
	if (state->check_index && is_not_gitdir)
		return error(_("'%s' outside a repository"), "--index");
	if (state->cached) {
		if (is_not_gitdir)
			return error(_("'%s' outside a repository"), "--cached");
		state->check_index = 1;
	}
	if (state->ita_only && (state->check_index || is_not_gitdir))
		state->ita_only = 0;
	if (state->check_index)
		state->unsafe_paths = 0;

	if (state->apply_verbosity <= verbosity_silent) {
		state->saved_error_routine = get_error_routine();
		state->saved_warn_routine = get_warn_routine();
		set_error_routine(mute_routine);
		set_warn_routine(mute_routine);
	}

	return 0;
}

static void set_default_whitespace_mode(struct apply_state *state)
{
	if (!state->whitespace_option && !apply_default_whitespace)
		state->ws_error_action = (state->apply ? warn_on_ws_error : nowarn_ws_error);
}

/*
 * This represents one "hunk" from a patch, starting with
 * "@@ -oldpos,oldlines +newpos,newlines @@" marker.  The
 * patch text is pointed at by patch, and its byte length
 * is stored in size.  leading and trailing are the number
 * of context lines.
 */
struct fragment {
	unsigned long leading, trailing;
	unsigned long oldpos, oldlines;
	unsigned long newpos, newlines;
	/*
	 * 'patch' is usually borrowed from buf in apply_patch(),
	 * but some codepaths store an allocated buffer.
	 */
	const char *patch;
	unsigned free_patch:1,
		rejected:1;
	int size;
	int linenr;
	struct fragment *next;
};

/*
 * When dealing with a binary patch, we reuse "leading" field
 * to store the type of the binary hunk, either deflated "delta"
 * or deflated "literal".
 */
#define binary_patch_method leading
#define BINARY_DELTA_DEFLATED	1
#define BINARY_LITERAL_DEFLATED 2

static void free_fragment_list(struct fragment *list)
{
	while (list) {
		struct fragment *next = list->next;
		if (list->free_patch)
			free((char *)list->patch);
		free(list);
		list = next;
	}
}

void release_patch(struct patch *patch)
{
	free_fragment_list(patch->fragments);
	free(patch->def_name);
	free(patch->old_name);
	free(patch->new_name);
	free(patch->result);
}

static void free_patch(struct patch *patch)
{
	release_patch(patch);
	free(patch);
}

static void free_patch_list(struct patch *list)
{
	while (list) {
		struct patch *next = list->next;
		free_patch(list);
		list = next;
	}
}

/*
 * A line in a file, len-bytes long (includes the terminating LF,
 * except for an incomplete line at the end if the file ends with
 * one), and its contents hashes to 'hash'.
 */
struct line {
	size_t len;
	unsigned hash : 24;
	unsigned flag : 8;
#define LINE_COMMON     1
#define LINE_PATCHED	2
};

/*
 * This represents a "file", which is an array of "lines".
 */
struct image {
	char *buf;
	size_t len;
	size_t nr;
	size_t alloc;
	struct line *line_allocated;
	struct line *line;
};

static uint32_t hash_line(const char *cp, size_t len)
{
	size_t i;
	uint32_t h;
	for (i = 0, h = 0; i < len; i++) {
		if (!isspace(cp[i])) {
			h = h * 3 + (cp[i] & 0xff);
		}
	}
	return h;
}

/*
 * Compare lines s1 of length n1 and s2 of length n2, ignoring
 * whitespace difference. Returns 1 if they match, 0 otherwise
 */
static int fuzzy_matchlines(const char *s1, size_t n1,
			    const char *s2, size_t n2)
{
	const char *end1 = s1 + n1;
	const char *end2 = s2 + n2;

	/* ignore line endings */
	while (s1 < end1 && (end1[-1] == '\r' || end1[-1] == '\n'))
		end1--;
	while (s2 < end2 && (end2[-1] == '\r' || end2[-1] == '\n'))
		end2--;

	while (s1 < end1 && s2 < end2) {
		if (isspace(*s1)) {
			/*
			 * Skip whitespace. We check on both buffers
			 * because we don't want "a b" to match "ab".
			 */
			if (!isspace(*s2))
				return 0;
			while (s1 < end1 && isspace(*s1))
				s1++;
			while (s2 < end2 && isspace(*s2))
				s2++;
		} else if (*s1++ != *s2++)
			return 0;
	}

	/* If we reached the end on one side only, lines don't match. */
	return s1 == end1 && s2 == end2;
}

static void add_line_info(struct image *img, const char *bol, size_t len, unsigned flag)
{
	ALLOC_GROW(img->line_allocated, img->nr + 1, img->alloc);
	img->line_allocated[img->nr].len = len;
	img->line_allocated[img->nr].hash = hash_line(bol, len);
	img->line_allocated[img->nr].flag = flag;
	img->nr++;
}

/*
 * "buf" has the file contents to be patched (read from various sources).
 * attach it to "image" and add line-based index to it.
 * "image" now owns the "buf".
 */
static void prepare_image(struct image *image, char *buf, size_t len,
			  int prepare_linetable)
{
	const char *cp, *ep;

	memset(image, 0, sizeof(*image));
	image->buf = buf;
	image->len = len;

	if (!prepare_linetable)
		return;

	ep = image->buf + image->len;
	cp = image->buf;
	while (cp < ep) {
		const char *next;
		for (next = cp; next < ep && *next != '\n'; next++)
			;
		if (next < ep)
			next++;
		add_line_info(image, cp, next - cp, 0);
		cp = next;
	}
	image->line = image->line_allocated;
}

static void clear_image(struct image *image)
{
	free(image->buf);
	free(image->line_allocated);
	memset(image, 0, sizeof(*image));
}

/* fmt must contain _one_ %s and no other substitution */
static void say_patch_name(FILE *output, const char *fmt, struct patch *patch)
{
	struct strbuf sb = STRBUF_INIT;

	if (patch->old_name && patch->new_name &&
	    strcmp(patch->old_name, patch->new_name)) {
		quote_c_style(patch->old_name, &sb, NULL, 0);
		strbuf_addstr(&sb, " => ");
		quote_c_style(patch->new_name, &sb, NULL, 0);
	} else {
		const char *n = patch->new_name;
		if (!n)
			n = patch->old_name;
		quote_c_style(n, &sb, NULL, 0);
	}
	fprintf(output, fmt, sb.buf);
	fputc('\n', output);
	strbuf_release(&sb);
}

#define SLOP (16)

static int read_patch_file(struct strbuf *sb, int fd)
{
	if (strbuf_read(sb, fd, 0) < 0)
		return error_errno("git apply: failed to read");

	/*
	 * Make sure that we have some slop in the buffer
	 * so that we can do speculative "memcmp" etc, and
	 * see to it that it is NUL-filled.
	 */
	strbuf_grow(sb, SLOP);
	memset(sb->buf + sb->len, 0, SLOP);
	return 0;
}

static unsigned long linelen(const char *buffer, unsigned long size)
{
	unsigned long len = 0;
	while (size--) {
		len++;
		if (*buffer++ == '\n')
			break;
	}
	return len;
}

static int is_dev_null(const char *str)
{
	return skip_prefix(str, "/dev/null", &str) && isspace(*str);
}

#define TERM_SPACE	1
#define TERM_TAB	2

static int name_terminate(int c, int terminate)
{
	if (c == ' ' && !(terminate & TERM_SPACE))
		return 0;
	if (c == '\t' && !(terminate & TERM_TAB))
		return 0;

	return 1;
}

/* remove double slashes to make --index work with such filenames */
static char *squash_slash(char *name)
{
	int i = 0, j = 0;

	if (!name)
		return NULL;

	while (name[i]) {
		if ((name[j++] = name[i++]) == '/')
			while (name[i] == '/')
				i++;
	}
	name[j] = '\0';
	return name;
}

static char *find_name_gnu(struct strbuf *root,
			   const char *line,
			   int p_value)
{
	struct strbuf name = STRBUF_INIT;
	char *cp;

	/*
	 * Proposed "new-style" GNU patch/diff format; see
	 * https://lore.kernel.org/git/7vll0wvb2a.fsf@assigned-by-dhcp.cox.net/
	 */
	if (unquote_c_style(&name, line, NULL)) {
		strbuf_release(&name);
		return NULL;
	}

	for (cp = name.buf; p_value; p_value--) {
		cp = strchr(cp, '/');
		if (!cp) {
			strbuf_release(&name);
			return NULL;
		}
		cp++;
	}

	strbuf_remove(&name, 0, cp - name.buf);
	if (root->len)
		strbuf_insert(&name, 0, root->buf, root->len);
	return squash_slash(strbuf_detach(&name, NULL));
}

static size_t sane_tz_len(const char *line, size_t len)
{
	const char *tz, *p;

	if (len < strlen(" +0500") || line[len-strlen(" +0500")] != ' ')
		return 0;
	tz = line + len - strlen(" +0500");

	if (tz[1] != '+' && tz[1] != '-')
		return 0;

	for (p = tz + 2; p != line + len; p++)
		if (!isdigit(*p))
			return 0;

	return line + len - tz;
}

static size_t tz_with_colon_len(const char *line, size_t len)
{
	const char *tz, *p;

	if (len < strlen(" +08:00") || line[len - strlen(":00")] != ':')
		return 0;
	tz = line + len - strlen(" +08:00");

	if (tz[0] != ' ' || (tz[1] != '+' && tz[1] != '-'))
		return 0;
	p = tz + 2;
	if (!isdigit(*p++) || !isdigit(*p++) || *p++ != ':' ||
	    !isdigit(*p++) || !isdigit(*p++))
		return 0;

	return line + len - tz;
}

static size_t date_len(const char *line, size_t len)
{
	const char *date, *p;

	if (len < strlen("72-02-05") || line[len-strlen("-05")] != '-')
		return 0;
	p = date = line + len - strlen("72-02-05");

	if (!isdigit(*p++) || !isdigit(*p++) || *p++ != '-' ||
	    !isdigit(*p++) || !isdigit(*p++) || *p++ != '-' ||
	    !isdigit(*p++) || !isdigit(*p++))	/* Not a date. */
		return 0;

	if (date - line >= strlen("19") &&
	    isdigit(date[-1]) && isdigit(date[-2]))	/* 4-digit year */
		date -= strlen("19");

	return line + len - date;
}

static size_t short_time_len(const char *line, size_t len)
{
	const char *time, *p;

	if (len < strlen(" 07:01:32") || line[len-strlen(":32")] != ':')
		return 0;
	p = time = line + len - strlen(" 07:01:32");

	/* Permit 1-digit hours? */
	if (*p++ != ' ' ||
	    !isdigit(*p++) || !isdigit(*p++) || *p++ != ':' ||
	    !isdigit(*p++) || !isdigit(*p++) || *p++ != ':' ||
	    !isdigit(*p++) || !isdigit(*p++))	/* Not a time. */
		return 0;

	return line + len - time;
}

static size_t fractional_time_len(const char *line, size_t len)
{
	const char *p;
	size_t n;

	/* Expected format: 19:41:17.620000023 */
	if (!len || !isdigit(line[len - 1]))
		return 0;
	p = line + len - 1;

	/* Fractional seconds. */
	while (p > line && isdigit(*p))
		p--;
	if (*p != '.')
		return 0;

	/* Hours, minutes, and whole seconds. */
	n = short_time_len(line, p - line);
	if (!n)
		return 0;

	return line + len - p + n;
}

static size_t trailing_spaces_len(const char *line, size_t len)
{
	const char *p;

	/* Expected format: ' ' x (1 or more)  */
	if (!len || line[len - 1] != ' ')
		return 0;

	p = line + len;
	while (p != line) {
		p--;
		if (*p != ' ')
			return line + len - (p + 1);
	}

	/* All spaces! */
	return len;
}

static size_t diff_timestamp_len(const char *line, size_t len)
{
	const char *end = line + len;
	size_t n;

	/*
	 * Posix: 2010-07-05 19:41:17
	 * GNU: 2010-07-05 19:41:17.620000023 -0500
	 */

	if (!isdigit(end[-1]))
		return 0;

	n = sane_tz_len(line, end - line);
	if (!n)
		n = tz_with_colon_len(line, end - line);
	end -= n;

	n = short_time_len(line, end - line);
	if (!n)
		n = fractional_time_len(line, end - line);
	end -= n;

	n = date_len(line, end - line);
	if (!n)	/* No date.  Too bad. */
		return 0;
	end -= n;

	if (end == line)	/* No space before date. */
		return 0;
	if (end[-1] == '\t') {	/* Success! */
		end--;
		return line + len - end;
	}
	if (end[-1] != ' ')	/* No space before date. */
		return 0;

	/* Whitespace damage. */
	end -= trailing_spaces_len(line, end - line);
	return line + len - end;
}

static char *find_name_common(struct strbuf *root,
			      const char *line,
			      const char *def,
			      int p_value,
			      const char *end,
			      int terminate)
{
	int len;
	const char *start = NULL;

	if (p_value == 0)
		start = line;
	while (line != end) {
		char c = *line;

		if (!end && isspace(c)) {
			if (c == '\n')
				break;
			if (name_terminate(c, terminate))
				break;
		}
		line++;
		if (c == '/' && !--p_value)
			start = line;
	}
	if (!start)
		return squash_slash(xstrdup_or_null(def));
	len = line - start;
	if (!len)
		return squash_slash(xstrdup_or_null(def));

	/*
	 * Generally we prefer the shorter name, especially
	 * if the other one is just a variation of that with
	 * something else tacked on to the end (ie "file.orig"
	 * or "file~").
	 */
	if (def) {
		int deflen = strlen(def);
		if (deflen < len && !strncmp(start, def, deflen))
			return squash_slash(xstrdup(def));
	}

	if (root->len) {
		char *ret = xstrfmt("%s%.*s", root->buf, len, start);
		return squash_slash(ret);
	}

	return squash_slash(xmemdupz(start, len));
}

static char *find_name(struct strbuf *root,
		       const char *line,
		       char *def,
		       int p_value,
		       int terminate)
{
	if (*line == '"') {
		char *name = find_name_gnu(root, line, p_value);
		if (name)
			return name;
	}

	return find_name_common(root, line, def, p_value, NULL, terminate);
}

static char *find_name_traditional(struct strbuf *root,
				   const char *line,
				   char *def,
				   int p_value)
{
	size_t len;
	size_t date_len;

	if (*line == '"') {
		char *name = find_name_gnu(root, line, p_value);
		if (name)
			return name;
	}

	len = strchrnul(line, '\n') - line;
	date_len = diff_timestamp_len(line, len);
	if (!date_len)
		return find_name_common(root, line, def, p_value, NULL, TERM_TAB);
	len -= date_len;

	return find_name_common(root, line, def, p_value, line + len, 0);
}

/*
 * Given the string after "--- " or "+++ ", guess the appropriate
 * p_value for the given patch.
 */
static int guess_p_value(struct apply_state *state, const char *nameline)
{
	char *name, *cp;
	int val = -1;

	if (is_dev_null(nameline))
		return -1;
	name = find_name_traditional(&state->root, nameline, NULL, 0);
	if (!name)
		return -1;
	cp = strchr(name, '/');
	if (!cp)
		val = 0;
	else if (state->prefix) {
		/*
		 * Does it begin with "a/$our-prefix" and such?  Then this is
		 * very likely to apply to our directory.
		 */
		if (starts_with(name, state->prefix))
			val = count_slashes(state->prefix);
		else {
			cp++;
			if (starts_with(cp, state->prefix))
				val = count_slashes(state->prefix) + 1;
		}
	}
	free(name);
	return val;
}

/*
 * Does the ---/+++ line have the POSIX timestamp after the last HT?
 * GNU diff puts epoch there to signal a creation/deletion event.  Is
 * this such a timestamp?
 */
static int has_epoch_timestamp(const char *nameline)
{
	/*
	 * We are only interested in epoch timestamp; any non-zero
	 * fraction cannot be one, hence "(\.0+)?" in the regexp below.
	 * For the same reason, the date must be either 1969-12-31 or
	 * 1970-01-01, and the seconds part must be "00".
	 */
	const char stamp_regexp[] =
		"^[0-2][0-9]:([0-5][0-9]):00(\\.0+)?"
		" "
		"([-+][0-2][0-9]:?[0-5][0-9])\n";
	const char *timestamp = NULL, *cp, *colon;
	static regex_t *stamp;
	regmatch_t m[10];
	int zoneoffset, epoch_hour, hour, minute;
	int status;

	for (cp = nameline; *cp != '\n'; cp++) {
		if (*cp == '\t')
			timestamp = cp + 1;
	}
	if (!timestamp)
		return 0;

	/*
	 * YYYY-MM-DD hh:mm:ss must be from either 1969-12-31
	 * (west of GMT) or 1970-01-01 (east of GMT)
	 */
	if (skip_prefix(timestamp, "1969-12-31 ", &timestamp))
		epoch_hour = 24;
	else if (skip_prefix(timestamp, "1970-01-01 ", &timestamp))
		epoch_hour = 0;
	else
		return 0;

	if (!stamp) {
		stamp = xmalloc(sizeof(*stamp));
		if (regcomp(stamp, stamp_regexp, REG_EXTENDED)) {
			warning(_("Cannot prepare timestamp regexp %s"),
				stamp_regexp);
			return 0;
		}
	}

	status = regexec(stamp, timestamp, ARRAY_SIZE(m), m, 0);
	if (status) {
		if (status != REG_NOMATCH)
			warning(_("regexec returned %d for input: %s"),
				status, timestamp);
		return 0;
	}

	hour = strtol(timestamp, NULL, 10);
	minute = strtol(timestamp + m[1].rm_so, NULL, 10);

	zoneoffset = strtol(timestamp + m[3].rm_so + 1, (char **) &colon, 10);
	if (*colon == ':')
		zoneoffset = zoneoffset * 60 + strtol(colon + 1, NULL, 10);
	else
		zoneoffset = (zoneoffset / 100) * 60 + (zoneoffset % 100);
	if (timestamp[m[3].rm_so] == '-')
		zoneoffset = -zoneoffset;

	return hour * 60 + minute - zoneoffset == epoch_hour * 60;
}

/*
 * Get the name etc info from the ---/+++ lines of a traditional patch header
 *
 * FIXME! The end-of-filename heuristics are kind of screwy. For existing
 * files, we can happily check the index for a match, but for creating a
 * new file we should try to match whatever "patch" does. I have no idea.
 */
static int parse_traditional_patch(struct apply_state *state,
				   const char *first,
				   const char *second,
				   struct patch *patch)
{
	char *name;

	first += 4;	/* skip "--- " */
	second += 4;	/* skip "+++ " */
	if (!state->p_value_known) {
		int p, q;
		p = guess_p_value(state, first);
		q = guess_p_value(state, second);
		if (p < 0) p = q;
		if (0 <= p && p == q) {
			state->p_value = p;
			state->p_value_known = 1;
		}
	}
	if (is_dev_null(first)) {
		patch->is_new = 1;
		patch->is_delete = 0;
		name = find_name_traditional(&state->root, second, NULL, state->p_value);
		patch->new_name = name;
	} else if (is_dev_null(second)) {
		patch->is_new = 0;
		patch->is_delete = 1;
		name = find_name_traditional(&state->root, first, NULL, state->p_value);
		patch->old_name = name;
	} else {
		char *first_name;
		first_name = find_name_traditional(&state->root, first, NULL, state->p_value);
		name = find_name_traditional(&state->root, second, first_name, state->p_value);
		free(first_name);
		if (has_epoch_timestamp(first)) {
			patch->is_new = 1;
			patch->is_delete = 0;
			patch->new_name = name;
		} else if (has_epoch_timestamp(second)) {
			patch->is_new = 0;
			patch->is_delete = 1;
			patch->old_name = name;
		} else {
			patch->old_name = name;
			patch->new_name = xstrdup_or_null(name);
		}
	}
	if (!name)
		return error(_("unable to find filename in patch at line %d"), state->linenr);

	return 0;
}

static int gitdiff_hdrend(struct gitdiff_data *state,
			  const char *line,
			  struct patch *patch)
{
	return 1;
}

/*
 * We're anal about diff header consistency, to make
 * sure that we don't end up having strange ambiguous
 * patches floating around.
 *
 * As a result, gitdiff_{old|new}name() will check
 * their names against any previous information, just
 * to make sure..
 */
#define DIFF_OLD_NAME 0
#define DIFF_NEW_NAME 1

static int gitdiff_verify_name(struct gitdiff_data *state,
			       const char *line,
			       int isnull,
			       char **name,
			       int side)
{
	if (!*name && !isnull) {
		*name = find_name(state->root, line, NULL, state->p_value, TERM_TAB);
		return 0;
	}

	if (*name) {
		char *another;
		if (isnull)
			return error(_("git apply: bad git-diff - expected /dev/null, got %s on line %d"),
				     *name, state->linenr);
		another = find_name(state->root, line, NULL, state->p_value, TERM_TAB);
		if (!another || strcmp(another, *name)) {
			free(another);
			return error((side == DIFF_NEW_NAME) ?
			    _("git apply: bad git-diff - inconsistent new filename on line %d") :
			    _("git apply: bad git-diff - inconsistent old filename on line %d"), state->linenr);
		}
		free(another);
	} else {
		if (!is_dev_null(line))
			return error(_("git apply: bad git-diff - expected /dev/null on line %d"), state->linenr);
	}

	return 0;
}

static int gitdiff_oldname(struct gitdiff_data *state,
			   const char *line,
			   struct patch *patch)
{
	return gitdiff_verify_name(state, line,
				   patch->is_new, &patch->old_name,
				   DIFF_OLD_NAME);
}

static int gitdiff_newname(struct gitdiff_data *state,
			   const char *line,
			   struct patch *patch)
{
	return gitdiff_verify_name(state, line,
				   patch->is_delete, &patch->new_name,
				   DIFF_NEW_NAME);
}

static int parse_mode_line(const char *line, int linenr, unsigned int *mode)
{
	char *end;
	*mode = strtoul(line, &end, 8);
	if (end == line || !isspace(*end))
		return error(_("invalid mode on line %d: %s"), linenr, line);
	return 0;
}

static int gitdiff_oldmode(struct gitdiff_data *state,
			   const char *line,
			   struct patch *patch)
{
	return parse_mode_line(line, state->linenr, &patch->old_mode);
}

static int gitdiff_newmode(struct gitdiff_data *state,
			   const char *line,
			   struct patch *patch)
{
	return parse_mode_line(line, state->linenr, &patch->new_mode);
}

static int gitdiff_delete(struct gitdiff_data *state,
			  const char *line,
			  struct patch *patch)
{
	patch->is_delete = 1;
	free(patch->old_name);
	patch->old_name = xstrdup_or_null(patch->def_name);
	return gitdiff_oldmode(state, line, patch);
}

static int gitdiff_newfile(struct gitdiff_data *state,
			   const char *line,
			   struct patch *patch)
{
	patch->is_new = 1;
	free(patch->new_name);
	patch->new_name = xstrdup_or_null(patch->def_name);
	return gitdiff_newmode(state, line, patch);
}

static int gitdiff_copysrc(struct gitdiff_data *state,
			   const char *line,
			   struct patch *patch)
{
	patch->is_copy = 1;
	free(patch->old_name);
	patch->old_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
	return 0;
}

static int gitdiff_copydst(struct gitdiff_data *state,
			   const char *line,
			   struct patch *patch)
{
	patch->is_copy = 1;
	free(patch->new_name);
	patch->new_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
	return 0;
}

static int gitdiff_renamesrc(struct gitdiff_data *state,
			     const char *line,
			     struct patch *patch)
{
	patch->is_rename = 1;
	free(patch->old_name);
	patch->old_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
	return 0;
}

static int gitdiff_renamedst(struct gitdiff_data *state,
			     const char *line,
			     struct patch *patch)
{
	patch->is_rename = 1;
	free(patch->new_name);
	patch->new_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
	return 0;
}

static int gitdiff_similarity(struct gitdiff_data *state,
			      const char *line,
			      struct patch *patch)
{
	unsigned long val = strtoul(line, NULL, 10);
	if (val <= 100)
		patch->score = val;
	return 0;
}

static int gitdiff_dissimilarity(struct gitdiff_data *state,
				 const char *line,
				 struct patch *patch)
{
	unsigned long val = strtoul(line, NULL, 10);
	if (val <= 100)
		patch->score = val;
	return 0;
}

static int gitdiff_index(struct gitdiff_data *state,
			 const char *line,
			 struct patch *patch)
{
	/*
	 * index line is N hexadecimal, "..", N hexadecimal,
	 * and optional space with octal mode.
	 */
	const char *ptr, *eol;
	int len;
	const unsigned hexsz = the_hash_algo->hexsz;

	ptr = strchr(line, '.');
	if (!ptr || ptr[1] != '.' || hexsz < ptr - line)
		return 0;
	len = ptr - line;
	memcpy(patch->old_oid_prefix, line, len);
	patch->old_oid_prefix[len] = 0;

	line = ptr + 2;
	ptr = strchr(line, ' ');
	eol = strchrnul(line, '\n');

	if (!ptr || eol < ptr)
		ptr = eol;
	len = ptr - line;

	if (hexsz < len)
		return 0;
	memcpy(patch->new_oid_prefix, line, len);
	patch->new_oid_prefix[len] = 0;
	if (*ptr == ' ')
		return gitdiff_oldmode(state, ptr + 1, patch);
	return 0;
}

/*
 * This is normal for a diff that doesn't change anything: we'll fall through
 * into the next diff. Tell the parser to break out.
 */
static int gitdiff_unrecognized(struct gitdiff_data *state,
				const char *line,
				struct patch *patch)
{
	return 1;
}

/*
 * Skip p_value leading components from "line"; as we do not accept
 * absolute paths, return NULL in that case.
 */
static const char *skip_tree_prefix(int p_value,
				    const char *line,
				    int llen)
{
	int nslash;
	int i;

	if (!p_value)
		return (llen && line[0] == '/') ? NULL : line;

	nslash = p_value;
	for (i = 0; i < llen; i++) {
		int ch = line[i];
		if (ch == '/' && --nslash <= 0)
			return (i == 0) ? NULL : &line[i + 1];
	}
	return NULL;
}

/*
 * This is to extract the same name that appears on "diff --git"
 * line.  We do not find and return anything if it is a rename
 * patch, and it is OK because we will find the name elsewhere.
 * We need to reliably find name only when it is mode-change only,
 * creation or deletion of an empty file.  In any of these cases,
 * both sides are the same name under a/ and b/ respectively.
 */
static char *git_header_name(int p_value,
			     const char *line,
			     int llen)
{
	const char *name;
	const char *second = NULL;
	size_t len, line_len;

	line += strlen("diff --git ");
	llen -= strlen("diff --git ");

	if (*line == '"') {
		const char *cp;
		struct strbuf first = STRBUF_INIT;
		struct strbuf sp = STRBUF_INIT;

		if (unquote_c_style(&first, line, &second))
			goto free_and_fail1;

		/* strip the a/b prefix including trailing slash */
		cp = skip_tree_prefix(p_value, first.buf, first.len);
		if (!cp)
			goto free_and_fail1;
		strbuf_remove(&first, 0, cp - first.buf);

		/*
		 * second points at one past closing dq of name.
		 * find the second name.
		 */
		while ((second < line + llen) && isspace(*second))
			second++;

		if (line + llen <= second)
			goto free_and_fail1;
		if (*second == '"') {
			if (unquote_c_style(&sp, second, NULL))
				goto free_and_fail1;
			cp = skip_tree_prefix(p_value, sp.buf, sp.len);
			if (!cp)
				goto free_and_fail1;
			/* They must match, otherwise ignore */
			if (strcmp(cp, first.buf))
				goto free_and_fail1;
			strbuf_release(&sp);
			return strbuf_detach(&first, NULL);
		}

		/* unquoted second */
		cp = skip_tree_prefix(p_value, second, line + llen - second);
		if (!cp)
			goto free_and_fail1;
		if (line + llen - cp != first.len ||
		    memcmp(first.buf, cp, first.len))
			goto free_and_fail1;
		return strbuf_detach(&first, NULL);

	free_and_fail1:
		strbuf_release(&first);
		strbuf_release(&sp);
		return NULL;
	}

	/* unquoted first name */
	name = skip_tree_prefix(p_value, line, llen);
	if (!name)
		return NULL;

	/*
	 * since the first name is unquoted, a dq if exists must be
	 * the beginning of the second name.
	 */
	for (second = name; second < line + llen; second++) {
		if (*second == '"') {
			struct strbuf sp = STRBUF_INIT;
			const char *np;

			if (unquote_c_style(&sp, second, NULL))
				goto free_and_fail2;

			np = skip_tree_prefix(p_value, sp.buf, sp.len);
			if (!np)
				goto free_and_fail2;

			len = sp.buf + sp.len - np;
			if (len < second - name &&
			    !strncmp(np, name, len) &&
			    isspace(name[len])) {
				/* Good */
				strbuf_remove(&sp, 0, np - sp.buf);
				return strbuf_detach(&sp, NULL);
			}

		free_and_fail2:
			strbuf_release(&sp);
			return NULL;
		}
	}

	/*
	 * Accept a name only if it shows up twice, exactly the same
	 * form.
	 */
	second = strchr(name, '\n');
	if (!second)
		return NULL;
	line_len = second - name;
	for (len = 0 ; ; len++) {
		switch (name[len]) {
		default:
			continue;
		case '\n':
			return NULL;
		case '\t': case ' ':
			/*
			 * Is this the separator between the preimage
			 * and the postimage pathname?  Again, we are
			 * only interested in the case where there is
			 * no rename, as this is only to set def_name
			 * and a rename patch has the names elsewhere
			 * in an unambiguous form.
			 */
			if (!name[len + 1])
				return NULL; /* no postimage name */
			second = skip_tree_prefix(p_value, name + len + 1,
						  line_len - (len + 1));
			if (!second)
				return NULL;
			/*
			 * Does len bytes starting at "name" and "second"
			 * (that are separated by one HT or SP we just
			 * found) exactly match?
			 */
			if (second[len] == '\n' && !strncmp(name, second, len))
				return xmemdupz(name, len);
		}
	}
}

static int check_header_line(int linenr, struct patch *patch)
{
	int extensions = (patch->is_delete == 1) + (patch->is_new == 1) +
			 (patch->is_rename == 1) + (patch->is_copy == 1);
	if (extensions > 1)
		return error(_("inconsistent header lines %d and %d"),
			     patch->extension_linenr, linenr);
	if (extensions && !patch->extension_linenr)
		patch->extension_linenr = linenr;
	return 0;
}

int parse_git_diff_header(struct strbuf *root,
			  int *linenr,
			  int p_value,
			  const char *line,
			  int len,
			  unsigned int size,
			  struct patch *patch)
{
	unsigned long offset;
	struct gitdiff_data parse_hdr_state;

	/* A git diff has explicit new/delete information, so we don't guess */
	patch->is_new = 0;
	patch->is_delete = 0;

	/*
	 * Some things may not have the old name in the
	 * rest of the headers anywhere (pure mode changes,
	 * or removing or adding empty files), so we get
	 * the default name from the header.
	 */
	patch->def_name = git_header_name(p_value, line, len);
	if (patch->def_name && root->len) {
		char *s = xstrfmt("%s%s", root->buf, patch->def_name);
		free(patch->def_name);
		patch->def_name = s;
	}

	line += len;
	size -= len;
	(*linenr)++;
	parse_hdr_state.root = root;
	parse_hdr_state.linenr = *linenr;
	parse_hdr_state.p_value = p_value;

	for (offset = len ; size > 0 ; offset += len, size -= len, line += len, (*linenr)++) {
		static const struct opentry {
			const char *str;
			int (*fn)(struct gitdiff_data *, const char *, struct patch *);
		} optable[] = {
			{ "@@ -", gitdiff_hdrend },
			{ "--- ", gitdiff_oldname },
			{ "+++ ", gitdiff_newname },
			{ "old mode ", gitdiff_oldmode },
			{ "new mode ", gitdiff_newmode },
			{ "deleted file mode ", gitdiff_delete },
			{ "new file mode ", gitdiff_newfile },
			{ "copy from ", gitdiff_copysrc },
			{ "copy to ", gitdiff_copydst },
			{ "rename old ", gitdiff_renamesrc },
			{ "rename new ", gitdiff_renamedst },
			{ "rename from ", gitdiff_renamesrc },
			{ "rename to ", gitdiff_renamedst },
			{ "similarity index ", gitdiff_similarity },
			{ "dissimilarity index ", gitdiff_dissimilarity },
			{ "index ", gitdiff_index },
			{ "", gitdiff_unrecognized },
		};
		int i;

		len = linelen(line, size);
		if (!len || line[len-1] != '\n')
			break;
		for (i = 0; i < ARRAY_SIZE(optable); i++) {
			const struct opentry *p = optable + i;
			int oplen = strlen(p->str);
			int res;
			if (len < oplen || memcmp(p->str, line, oplen))
				continue;
			res = p->fn(&parse_hdr_state, line + oplen, patch);
			if (res < 0)
				return -1;
			if (check_header_line(*linenr, patch))
				return -1;
			if (res > 0)
				goto done;
			break;
		}
	}

done:
	if (!patch->old_name && !patch->new_name) {
		if (!patch->def_name) {
			error(Q_("git diff header lacks filename information when removing "
				 "%d leading pathname component (line %d)",
				 "git diff header lacks filename information when removing "
				 "%d leading pathname components (line %d)",
				 parse_hdr_state.p_value),
			      parse_hdr_state.p_value, *linenr);
			return -128;
		}
		patch->old_name = xstrdup(patch->def_name);
		patch->new_name = xstrdup(patch->def_name);
	}
	if ((!patch->new_name && !patch->is_delete) ||
	    (!patch->old_name && !patch->is_new)) {
		error(_("git diff header lacks filename information "
			"(line %d)"), *linenr);
		return -128;
	}
	patch->is_toplevel_relative = 1;
	return offset;
}

static int parse_num(const char *line, unsigned long *p)
{
	char *ptr;

	if (!isdigit(*line))
		return 0;
	*p = strtoul(line, &ptr, 10);
	return ptr - line;
}

static int parse_range(const char *line, int len, int offset, const char *expect,
		       unsigned long *p1, unsigned long *p2)
{
	int digits, ex;

	if (offset < 0 || offset >= len)
		return -1;
	line += offset;
	len -= offset;

	digits = parse_num(line, p1);
	if (!digits)
		return -1;

	offset += digits;
	line += digits;
	len -= digits;

	*p2 = 1;
	if (*line == ',') {
		digits = parse_num(line+1, p2);
		if (!digits)
			return -1;

		offset += digits+1;
		line += digits+1;
		len -= digits+1;
	}

	ex = strlen(expect);
	if (ex > len)
		return -1;
	if (memcmp(line, expect, ex))
		return -1;

	return offset + ex;
}

static void recount_diff(const char *line, int size, struct fragment *fragment)
{
	int oldlines = 0, newlines = 0, ret = 0;

	if (size < 1) {
		warning("recount: ignore empty hunk");
		return;
	}

	for (;;) {
		int len = linelen(line, size);
		size -= len;
		line += len;

		if (size < 1)
			break;

		switch (*line) {
		case ' ': case '\n':
			newlines++;
			/* fall through */
		case '-':
			oldlines++;
			continue;
		case '+':
			newlines++;
			continue;
		case '\\':
			continue;
		case '@':
			ret = size < 3 || !starts_with(line, "@@ ");
			break;
		case 'd':
			ret = size < 5 || !starts_with(line, "diff ");
			break;
		default:
			ret = -1;
			break;
		}
		if (ret) {
			warning(_("recount: unexpected line: %.*s"),
				(int)linelen(line, size), line);
			return;
		}
		break;
	}
	fragment->oldlines = oldlines;
	fragment->newlines = newlines;
}

/*
 * Parse a unified diff fragment header of the
 * form "@@ -a,b +c,d @@"
 */
static int parse_fragment_header(const char *line, int len, struct fragment *fragment)
{
	int offset;

	if (!len || line[len-1] != '\n')
		return -1;

	/* Figure out the number of lines in a fragment */
	offset = parse_range(line, len, 4, " +", &fragment->oldpos, &fragment->oldlines);
	offset = parse_range(line, len, offset, " @@", &fragment->newpos, &fragment->newlines);

	return offset;
}

/*
 * Find file diff header
 *
 * Returns:
 *  -1 if no header was found
 *  -128 in case of error
 *   the size of the header in bytes (called "offset") otherwise
 */
static int find_header(struct apply_state *state,
		       const char *line,
		       unsigned long size,
		       int *hdrsize,
		       struct patch *patch)
{
	unsigned long offset, len;

	patch->is_toplevel_relative = 0;
	patch->is_rename = patch->is_copy = 0;
	patch->is_new = patch->is_delete = -1;
	patch->old_mode = patch->new_mode = 0;
	patch->old_name = patch->new_name = NULL;
	for (offset = 0; size > 0; offset += len, size -= len, line += len, state->linenr++) {
		unsigned long nextlen;

		len = linelen(line, size);
		if (!len)
			break;

		/* Testing this early allows us to take a few shortcuts.. */
		if (len < 6)
			continue;

		/*
		 * Make sure we don't find any unconnected patch fragments.
		 * That's a sign that we didn't find a header, and that a
		 * patch has become corrupted/broken up.
		 */
		if (!memcmp("@@ -", line, 4)) {
			struct fragment dummy;
			if (parse_fragment_header(line, len, &dummy) < 0)
				continue;
			error(_("patch fragment without header at line %d: %.*s"),
				     state->linenr, (int)len-1, line);
			return -128;
		}

		if (size < len + 6)
			break;

		/*
		 * Git patch? It might not have a real patch, just a rename
		 * or mode change, so we handle that specially
		 */
		if (!memcmp("diff --git ", line, 11)) {
			int git_hdr_len = parse_git_diff_header(&state->root, &state->linenr,
								state->p_value, line, len,
								size, patch);
			if (git_hdr_len < 0)
				return -128;
			if (git_hdr_len <= len)
				continue;
			*hdrsize = git_hdr_len;
			return offset;
		}

		/* --- followed by +++ ? */
		if (memcmp("--- ", line,  4) || memcmp("+++ ", line + len, 4))
			continue;

		/*
		 * We only accept unified patches, so we want it to
		 * at least have "@@ -a,b +c,d @@\n", which is 14 chars
		 * minimum ("@@ -0,0 +1 @@\n" is the shortest).
		 */
		nextlen = linelen(line + len, size - len);
		if (size < nextlen + 14 || memcmp("@@ -", line + len + nextlen, 4))
			continue;

		/* Ok, we'll consider it a patch */
		if (parse_traditional_patch(state, line, line+len, patch))
			return -128;
		*hdrsize = len + nextlen;
		state->linenr += 2;
		return offset;
	}
	return -1;
}

static void record_ws_error(struct apply_state *state,
			    unsigned result,
			    const char *line,
			    int len,
			    int linenr)
{
	char *err;

	if (!result)
		return;

	state->whitespace_error++;
	if (state->squelch_whitespace_errors &&
	    state->squelch_whitespace_errors < state->whitespace_error)
		return;

	err = whitespace_error_string(result);
	if (state->apply_verbosity > verbosity_silent)
		fprintf(stderr, "%s:%d: %s.\n%.*s\n",
			state->patch_input_file, linenr, err, len, line);
	free(err);
}

static void check_whitespace(struct apply_state *state,
			     const char *line,
			     int len,
			     unsigned ws_rule)
{
	unsigned result = ws_check(line + 1, len - 1, ws_rule);

	record_ws_error(state, result, line + 1, len - 2, state->linenr);
}

/*
 * Check if the patch has context lines with CRLF or
 * the patch wants to remove lines with CRLF.
 */
static void check_old_for_crlf(struct patch *patch, const char *line, int len)
{
	if (len >= 2 && line[len-1] == '\n' && line[len-2] == '\r') {
		patch->ws_rule |= WS_CR_AT_EOL;
		patch->crlf_in_old = 1;
	}
}


/*
 * Parse a unified diff. Note that this really needs to parse each
 * fragment separately, since the only way to know the difference
 * between a "---" that is part of a patch, and a "---" that starts
 * the next patch is to look at the line counts..
 */
static int parse_fragment(struct apply_state *state,
			  const char *line,
			  unsigned long size,
			  struct patch *patch,
			  struct fragment *fragment)
{
	int added, deleted;
	int len = linelen(line, size), offset;
	unsigned long oldlines, newlines;
	unsigned long leading, trailing;

	offset = parse_fragment_header(line, len, fragment);
	if (offset < 0)
		return -1;
	if (offset > 0 && patch->recount)
		recount_diff(line + offset, size - offset, fragment);
	oldlines = fragment->oldlines;
	newlines = fragment->newlines;
	leading = 0;
	trailing = 0;

	/* Parse the thing.. */
	line += len;
	size -= len;
	state->linenr++;
	added = deleted = 0;
	for (offset = len;
	     0 < size;
	     offset += len, size -= len, line += len, state->linenr++) {
		if (!oldlines && !newlines)
			break;
		len = linelen(line, size);
		if (!len || line[len-1] != '\n')
			return -1;
		switch (*line) {
		default:
			return -1;
		case '\n': /* newer GNU diff, an empty context line */
		case ' ':
			oldlines--;
			newlines--;
			if (!deleted && !added)
				leading++;
			trailing++;
			check_old_for_crlf(patch, line, len);
			if (!state->apply_in_reverse &&
			    state->ws_error_action == correct_ws_error)
				check_whitespace(state, line, len, patch->ws_rule);
			break;
		case '-':
			if (!state->apply_in_reverse)
				check_old_for_crlf(patch, line, len);
			if (state->apply_in_reverse &&
			    state->ws_error_action != nowarn_ws_error)
				check_whitespace(state, line, len, patch->ws_rule);
			deleted++;
			oldlines--;
			trailing = 0;
			break;
		case '+':
			if (state->apply_in_reverse)
				check_old_for_crlf(patch, line, len);
			if (!state->apply_in_reverse &&
			    state->ws_error_action != nowarn_ws_error)
				check_whitespace(state, line, len, patch->ws_rule);
			added++;
			newlines--;
			trailing = 0;
			break;

		/*
		 * We allow "\ No newline at end of file". Depending
		 * on locale settings when the patch was produced we
		 * don't know what this line looks like. The only
		 * thing we do know is that it begins with "\ ".
		 * Checking for 12 is just for sanity check -- any
		 * l10n of "\ No newline..." is at least that long.
		 */
		case '\\':
			if (len < 12 || memcmp(line, "\\ ", 2))
				return -1;
			break;
		}
	}
	if (oldlines || newlines)
		return -1;
	if (!patch->recount && !deleted && !added)
		return -1;

	fragment->leading = leading;
	fragment->trailing = trailing;

	/*
	 * If a fragment ends with an incomplete line, we failed to include
	 * it in the above loop because we hit oldlines == newlines == 0
	 * before seeing it.
	 */
	if (12 < size && !memcmp(line, "\\ ", 2))
		offset += linelen(line, size);

	patch->lines_added += added;
	patch->lines_deleted += deleted;

	if (0 < patch->is_new && oldlines)
		return error(_("new file depends on old contents"));
	if (0 < patch->is_delete && newlines)
		return error(_("deleted file still has contents"));
	return offset;
}

/*
 * We have seen "diff --git a/... b/..." header (or a traditional patch
 * header).  Read hunks that belong to this patch into fragments and hang
 * them to the given patch structure.
 *
 * The (fragment->patch, fragment->size) pair points into the memory given
 * by the caller, not a copy, when we return.
 *
 * Returns:
 *   -1 in case of error,
 *   the number of bytes in the patch otherwise.
 */
static int parse_single_patch(struct apply_state *state,
			      const char *line,
			      unsigned long size,
			      struct patch *patch)
{
	unsigned long offset = 0;
	unsigned long oldlines = 0, newlines = 0, context = 0;
	struct fragment **fragp = &patch->fragments;

	while (size > 4 && !memcmp(line, "@@ -", 4)) {
		struct fragment *fragment;
		int len;

		CALLOC_ARRAY(fragment, 1);
		fragment->linenr = state->linenr;
		len = parse_fragment(state, line, size, patch, fragment);
		if (len <= 0) {
			free(fragment);
			return error(_("corrupt patch at line %d"), state->linenr);
		}
		fragment->patch = line;
		fragment->size = len;
		oldlines += fragment->oldlines;
		newlines += fragment->newlines;
		context += fragment->leading + fragment->trailing;

		*fragp = fragment;
		fragp = &fragment->next;

		offset += len;
		line += len;
		size -= len;
	}

	/*
	 * If something was removed (i.e. we have old-lines) it cannot
	 * be creation, and if something was added it cannot be
	 * deletion.  However, the reverse is not true; --unified=0
	 * patches that only add are not necessarily creation even
	 * though they do not have any old lines, and ones that only
	 * delete are not necessarily deletion.
	 *
	 * Unfortunately, a real creation/deletion patch do _not_ have
	 * any context line by definition, so we cannot safely tell it
	 * apart with --unified=0 insanity.  At least if the patch has
	 * more than one hunk it is not creation or deletion.
	 */
	if (patch->is_new < 0 &&
	    (oldlines || (patch->fragments && patch->fragments->next)))
		patch->is_new = 0;
	if (patch->is_delete < 0 &&
	    (newlines || (patch->fragments && patch->fragments->next)))
		patch->is_delete = 0;

	if (0 < patch->is_new && oldlines)
		return error(_("new file %s depends on old contents"), patch->new_name);
	if (0 < patch->is_delete && newlines)
		return error(_("deleted file %s still has contents"), patch->old_name);
	if (!patch->is_delete && !newlines && context && state->apply_verbosity > verbosity_silent)
		fprintf_ln(stderr,
			   _("** warning: "
			     "file %s becomes empty but is not deleted"),
			   patch->new_name);

	return offset;
}

static inline int metadata_changes(struct patch *patch)
{
	return	patch->is_rename > 0 ||
		patch->is_copy > 0 ||
		patch->is_new > 0 ||
		patch->is_delete ||
		(patch->old_mode && patch->new_mode &&
		 patch->old_mode != patch->new_mode);
}

static char *inflate_it(const void *data, unsigned long size,
			unsigned long inflated_size)
{
	git_zstream stream;
	void *out;
	int st;

	memset(&stream, 0, sizeof(stream));

	stream.next_in = (unsigned char *)data;
	stream.avail_in = size;
	stream.next_out = out = xmalloc(inflated_size);
	stream.avail_out = inflated_size;
	git_inflate_init(&stream);
	st = git_inflate(&stream, Z_FINISH);
	git_inflate_end(&stream);
	if ((st != Z_STREAM_END) || stream.total_out != inflated_size) {
		free(out);
		return NULL;
	}
	return out;
}

/*
 * Read a binary hunk and return a new fragment; fragment->patch
 * points at an allocated memory that the caller must free, so
 * it is marked as "->free_patch = 1".
 */
static struct fragment *parse_binary_hunk(struct apply_state *state,
					  char **buf_p,
					  unsigned long *sz_p,
					  int *status_p,
					  int *used_p)
{
	/*
	 * Expect a line that begins with binary patch method ("literal"
	 * or "delta"), followed by the length of data before deflating.
	 * a sequence of 'length-byte' followed by base-85 encoded data
	 * should follow, terminated by a newline.
	 *
	 * Each 5-byte sequence of base-85 encodes up to 4 bytes,
	 * and we would limit the patch line to 66 characters,
	 * so one line can fit up to 13 groups that would decode
	 * to 52 bytes max.  The length byte 'A'-'Z' corresponds
	 * to 1-26 bytes, and 'a'-'z' corresponds to 27-52 bytes.
	 */
	int llen, used;
	unsigned long size = *sz_p;
	char *buffer = *buf_p;
	int patch_method;
	unsigned long origlen;
	char *data = NULL;
	int hunk_size = 0;
	struct fragment *frag;

	llen = linelen(buffer, size);
	used = llen;

	*status_p = 0;

	if (starts_with(buffer, "delta ")) {
		patch_method = BINARY_DELTA_DEFLATED;
		origlen = strtoul(buffer + 6, NULL, 10);
	}
	else if (starts_with(buffer, "literal ")) {
		patch_method = BINARY_LITERAL_DEFLATED;
		origlen = strtoul(buffer + 8, NULL, 10);
	}
	else
		return NULL;

	state->linenr++;
	buffer += llen;
	size -= llen;
	while (1) {
		int byte_length, max_byte_length, newsize;
		llen = linelen(buffer, size);
		used += llen;
		state->linenr++;
		if (llen == 1) {
			/* consume the blank line */
			buffer++;
			size--;
			break;
		}
		/*
		 * Minimum line is "A00000\n" which is 7-byte long,
		 * and the line length must be multiple of 5 plus 2.
		 */
		if ((llen < 7) || (llen-2) % 5)
			goto corrupt;
		max_byte_length = (llen - 2) / 5 * 4;
		byte_length = *buffer;
		if ('A' <= byte_length && byte_length <= 'Z')
			byte_length = byte_length - 'A' + 1;
		else if ('a' <= byte_length && byte_length <= 'z')
			byte_length = byte_length - 'a' + 27;
		else
			goto corrupt;
		/* if the input length was not multiple of 4, we would
		 * have filler at the end but the filler should never
		 * exceed 3 bytes
		 */
		if (max_byte_length < byte_length ||
		    byte_length <= max_byte_length - 4)
			goto corrupt;
		newsize = hunk_size + byte_length;
		data = xrealloc(data, newsize);
		if (decode_85(data + hunk_size, buffer + 1, byte_length))
			goto corrupt;
		hunk_size = newsize;
		buffer += llen;
		size -= llen;
	}

	CALLOC_ARRAY(frag, 1);
	frag->patch = inflate_it(data, hunk_size, origlen);
	frag->free_patch = 1;
	if (!frag->patch)
		goto corrupt;
	free(data);
	frag->size = origlen;
	*buf_p = buffer;
	*sz_p = size;
	*used_p = used;
	frag->binary_patch_method = patch_method;
	return frag;

 corrupt:
	free(data);
	*status_p = -1;
	error(_("corrupt binary patch at line %d: %.*s"),
	      state->linenr-1, llen-1, buffer);
	return NULL;
}

/*
 * Returns:
 *   -1 in case of error,
 *   the length of the parsed binary patch otherwise
 */
static int parse_binary(struct apply_state *state,
			char *buffer,
			unsigned long size,
			struct patch *patch)
{
	/*
	 * We have read "GIT binary patch\n"; what follows is a line
	 * that says the patch method (currently, either "literal" or
	 * "delta") and the length of data before deflating; a
	 * sequence of 'length-byte' followed by base-85 encoded data
	 * follows.
	 *
	 * When a binary patch is reversible, there is another binary
	 * hunk in the same format, starting with patch method (either
	 * "literal" or "delta") with the length of data, and a sequence
	 * of length-byte + base-85 encoded data, terminated with another
	 * empty line.  This data, when applied to the postimage, produces
	 * the preimage.
	 */
	struct fragment *forward;
	struct fragment *reverse;
	int status;
	int used, used_1;

	forward = parse_binary_hunk(state, &buffer, &size, &status, &used);
	if (!forward && !status)
		/* there has to be one hunk (forward hunk) */
		return error(_("unrecognized binary patch at line %d"), state->linenr-1);
	if (status)
		/* otherwise we already gave an error message */
		return status;

	reverse = parse_binary_hunk(state, &buffer, &size, &status, &used_1);
	if (reverse)
		used += used_1;
	else if (status) {
		/*
		 * Not having reverse hunk is not an error, but having
		 * a corrupt reverse hunk is.
		 */
		free((void*) forward->patch);
		free(forward);
		return status;
	}
	forward->next = reverse;
	patch->fragments = forward;
	patch->is_binary = 1;
	return used;
}

static void prefix_one(struct apply_state *state, char **name)
{
	char *old_name = *name;
	if (!old_name)
		return;
	*name = prefix_filename(state->prefix, *name);
	free(old_name);
}

static void prefix_patch(struct apply_state *state, struct patch *p)
{
	if (!state->prefix || p->is_toplevel_relative)
		return;
	prefix_one(state, &p->new_name);
	prefix_one(state, &p->old_name);
}

/*
 * include/exclude
 */

static void add_name_limit(struct apply_state *state,
			   const char *name,
			   int exclude)
{
	struct string_list_item *it;

	it = string_list_append(&state->limit_by_name, name);
	it->util = exclude ? NULL : (void *) 1;
}

static int use_patch(struct apply_state *state, struct patch *p)
{
	const char *pathname = p->new_name ? p->new_name : p->old_name;
	int i;

	/* Paths outside are not touched regardless of "--include" */
	if (state->prefix && *state->prefix) {
		const char *rest;
		if (!skip_prefix(pathname, state->prefix, &rest) || !*rest)
			return 0;
	}

	/* See if it matches any of exclude/include rule */
	for (i = 0; i < state->limit_by_name.nr; i++) {
		struct string_list_item *it = &state->limit_by_name.items[i];
		if (!wildmatch(it->string, pathname, 0))
			return (it->util != NULL);
	}

	/*
	 * If we had any include, a path that does not match any rule is
	 * not used.  Otherwise, we saw bunch of exclude rules (or none)
	 * and such a path is used.
	 */
	return !state->has_include;
}

/*
 * Read the patch text in "buffer" that extends for "size" bytes; stop
 * reading after seeing a single patch (i.e. changes to a single file).
 * Create fragments (i.e. patch hunks) and hang them to the given patch.
 *
 * Returns:
 *   -1 if no header was found or parse_binary() failed,
 *   -128 on another error,
 *   the number of bytes consumed otherwise,
 *     so that the caller can call us again for the next patch.
 */
static int parse_chunk(struct apply_state *state, char *buffer, unsigned long size, struct patch *patch)
{
	int hdrsize, patchsize;
	int offset = find_header(state, buffer, size, &hdrsize, patch);

	if (offset < 0)
		return offset;

	prefix_patch(state, patch);

	if (!use_patch(state, patch))
		patch->ws_rule = 0;
	else if (patch->new_name)
		patch->ws_rule = whitespace_rule(state->repo->index,
						 patch->new_name);
	else
		patch->ws_rule = whitespace_rule(state->repo->index,
						 patch->old_name);

	patchsize = parse_single_patch(state,
				       buffer + offset + hdrsize,
				       size - offset - hdrsize,
				       patch);

	if (patchsize < 0)
		return -128;

	if (!patchsize) {
		static const char git_binary[] = "GIT binary patch\n";
		int hd = hdrsize + offset;
		unsigned long llen = linelen(buffer + hd, size - hd);

		if (llen == sizeof(git_binary) - 1 &&
		    !memcmp(git_binary, buffer + hd, llen)) {
			int used;
			state->linenr++;
			used = parse_binary(state, buffer + hd + llen,
					    size - hd - llen, patch);
			if (used < 0)
				return -1;
			if (used)
				patchsize = used + llen;
			else
				patchsize = 0;
		}
		else if (!memcmp(" differ\n", buffer + hd + llen - 8, 8)) {
			static const char *binhdr[] = {
				"Binary files ",
				"Files ",
				NULL,
			};
			int i;
			for (i = 0; binhdr[i]; i++) {
				int len = strlen(binhdr[i]);
				if (len < size - hd &&
				    !memcmp(binhdr[i], buffer + hd, len)) {
					state->linenr++;
					patch->is_binary = 1;
					patchsize = llen;
					break;
				}
			}
		}

		/* Empty patch cannot be applied if it is a text patch
		 * without metadata change.  A binary patch appears
		 * empty to us here.
		 */
		if ((state->apply || state->check) &&
		    (!patch->is_binary && !metadata_changes(patch))) {
			error(_("patch with only garbage at line %d"), state->linenr);
			return -128;
		}
	}

	return offset + hdrsize + patchsize;
}

static void reverse_patches(struct patch *p)
{
	for (; p; p = p->next) {
		struct fragment *frag = p->fragments;

		SWAP(p->new_name, p->old_name);
		SWAP(p->new_mode, p->old_mode);
		SWAP(p->is_new, p->is_delete);
		SWAP(p->lines_added, p->lines_deleted);
		SWAP(p->old_oid_prefix, p->new_oid_prefix);

		for (; frag; frag = frag->next) {
			SW