/*
 * apply.c
 *
 * Copyright (C) Linus Torvalds, 2005
 *
 * This applies patches on top of some (arbitrary) version of the SCM.
 *
 */
#include <fnmatch.h>
#include "cache.h"
#include "cache-tree.h"
#include "quote.h"
#include "blob.h"
#include "delta.h"
#include "builtin.h"

/*
 *  --check turns on checking that the working tree matches the
 *    files that are being modified, but doesn't apply the patch
 *  --stat does just a diffstat, and doesn't actually apply
 *  --numstat does numeric diffstat, and doesn't actually apply
 *  --index-info shows the old and new index info for paths if available.
 *  --index updates the cache as well.
 *  --cached updates only the cache without ever touching the working tree.
 */
static const char *prefix;
static int prefix_length = -1;
static int newfd = -1;

static int p_value = 1;
static int allow_binary_replacement = 0;
static int check_index = 0;
static int write_index = 0;
static int cached = 0;
static int diffstat = 0;
static int numstat = 0;
static int summary = 0;
static int check = 0;
static int apply = 1;
static int no_add = 0;
static int show_index_info = 0;
static int line_termination = '\n';
static unsigned long p_context = -1;
static const char apply_usage[] =
"git-apply [--stat] [--numstat] [--summary] [--check] [--index] [--cached] [--apply] [--no-add] [--index-info] [--allow-binary-replacement] [-z] [-pNUM] [-CNUM] [--whitespace=<nowarn|warn|error|error-all|strip>] <patch>...";

static enum whitespace_eol {
        nowarn_whitespace,
        warn_on_whitespace,
        error_on_whitespace,
        strip_whitespace,
} new_whitespace = warn_on_whitespace;
static int whitespace_error = 0;
static int squelch_whitespace_errors = 5;
static int applied_after_stripping = 0;
static const char *patch_input_file = NULL;

static void parse_whitespace_option(const char *option)
{
        if (!option) {
                new_whitespace = warn_on_whitespace;
                return;
        }
        if (!strcmp(option, "warn")) {
                new_whitespace = warn_on_whitespace;
                return;
        }
        if (!strcmp(option, "nowarn")) {
                new_whitespace = nowarn_whitespace;
                return;
        }
        if (!strcmp(option, "error")) {
                new_whitespace = error_on_whitespace;
                return;
        }
        if (!strcmp(option, "error-all")) {
                new_whitespace = error_on_whitespace;
                squelch_whitespace_errors = 0;
                return;
        }
        if (!strcmp(option, "strip")) {
                new_whitespace = strip_whitespace;
                return;
        }
        die("unrecognized whitespace option '%s'", option);
}

static void set_default_whitespace_mode(const char *whitespace_option)
{
        if (!whitespace_option && !apply_default_whitespace) {
                new_whitespace = (apply
                                  ? warn_on_whitespace
                                  : nowarn_whitespace);
        }
}

/*
 * For "diff-stat" like behaviour, we keep track of the biggest change
 * we've seen, and the longest filename. That allows us to do simple
 * scaling.
 */
static int max_change, max_len;

/*
 * Various "current state", notably line numbers and what
 * file (and how) we're patching right now.. The "is_xxxx"
 * things are flags, where -1 means "don't know yet".
 */
static int linenr = 1;

struct fragment {
        unsigned long leading, trailing;
        unsigned long oldpos, oldlines;
        unsigned long newpos, newlines;
        const char *patch;
        int size;
        struct fragment *next;
};

struct patch {
        char *new_name, *old_name, *def_name;
        unsigned int old_mode, new_mode;
        int is_rename, is_copy, is_new, is_delete, is_binary, is_reverse;
#define BINARY_DELTA_DEFLATED 1
#define BINARY_LITERAL_DEFLATED 2
        unsigned long deflate_origlen;
        int lines_added, lines_deleted;
        int score;
        int inaccurate_eof:1;
        struct fragment *fragments;
        char *result;
        unsigned long resultsize;
        char old_sha1_prefix[41];
        char new_sha1_prefix[41];
        struct patch *next;
};

#define CHUNKSIZE (8192)
#define SLOP (16)

static void *read_patch_file(int fd, unsigned long *sizep)
{
        unsigned long size = 0, alloc = CHUNKSIZE;
        void *buffer = xmalloc(alloc);

        for (;;) {
                int nr = alloc - size;
                if (nr < 1024) {
                        alloc += CHUNKSIZE;
                        buffer = xrealloc(buffer, alloc);
                        nr = alloc - size;
                }
                nr = xread(fd, (char *) buffer + size, nr);
                if (!nr)
                        break;
                if (nr < 0)
                        die("git-apply: read returned %s", strerror(errno));
                size += nr;
        }
        *sizep = size;

        /*
         * 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.
         */
        if (alloc < size + SLOP)
                buffer = xrealloc(buffer, size + SLOP);
        memset((char *) buffer + size, 0, SLOP);
        return buffer;
}

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 !memcmp("/dev/null", str, 9) && isspace(str[9]);
}

#define TERM_SPACE      1
#define TERM_TAB        2

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

        return 1;
}

static char * find_name(const char *line, char *def, int p_value, int terminate)
{
        int len;
        const char *start = line;
        char *name;

        if (*line == '"') {
                /* Proposed "new-style" GNU patch/diff format; see
                 * http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2
                 */
                name = unquote_c_style(line, NULL);
                if (name) {
                        char *cp = name;
                        while (p_value) {
                                cp = strchr(name, '/');
                                if (!cp)
                                        break;
                                cp++;
                                p_value--;
                        }
                        if (cp) {
                                /* name can later be freed, so we need
                                 * to memmove, not just return cp
                                 */
                                memmove(name, cp, strlen(cp) + 1);
                                free(def);
                                return name;
                        }
                        else {
                                free(name);
                                name = NULL;
                        }
                }
        }

        for (;;) {
                char c = *line;

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

        name = xmalloc(len + 1);
        memcpy(name, start, len);
        name[len] = 0;
        free(def);
        return name;
}

/*
 * Get the name etc info from the --/+++ lines of a traditional patch header
 *
 * NOTE! This hardcodes "-p1" behaviour in filename detection.
 *
 * 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 void parse_traditional_patch(const char *first, const char *second, struct patch *patch)
{
        char *name;

        first += 4;     /* skip "--- " */
        second += 4;    /* skip "+++ " */
        if (is_dev_null(first)) {
                patch->is_new = 1;
                patch->is_delete = 0;
                name = find_name(second, NULL, p_value, TERM_SPACE | TERM_TAB);
                patch->new_name = name;
        } else if (is_dev_null(second)) {
                patch->is_new = 0;
                patch->is_delete = 1;
                name = find_name(first, NULL, p_value, TERM_SPACE | TERM_TAB);
                patch->old_name = name;
        } else {
                name = find_name(first, NULL, p_value, TERM_SPACE | TERM_TAB);
                name = find_name(second, name, p_value, TERM_SPACE | TERM_TAB);
                patch->old_name = patch->new_name = name;
        }
        if (!name)
                die("unable to find filename in patch at line %d", linenr);
}

static int gitdiff_hdrend(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..
 */
static char *gitdiff_verify_name(const char *line, int isnull, char *orig_name, const char *oldnew)
{
        if (!orig_name && !isnull)
                return find_name(line, NULL, 1, 0);

        if (orig_name) {
                int len;
                const char *name;
                char *another;
                name = orig_name;
                len = strlen(name);
                if (isnull)
                        die("git-apply: bad git-diff - expected /dev/null, got %s on line %d", name, linenr);
                another = find_name(line, NULL, 1, 0);
                if (!another || memcmp(another, name, len))
                        die("git-apply: bad git-diff - inconsistent %s filename on line %d", oldnew, linenr);
                free(another);
                return orig_name;
        }
        else {
                /* expect "/dev/null" */
                if (memcmp("/dev/null", line, 9) || line[9] != '\n')
                        die("git-apply: bad git-diff - expected /dev/null on line %d", linenr);
                return NULL;
        }
}

static int gitdiff_oldname(const char *line, struct patch *patch)
{
        patch->old_name = gitdiff_verify_name(line, patch->is_new, patch->old_name, "old");
        return 0;
}

static int gitdiff_newname(const char *line, struct patch *patch)
{
        patch->new_name = gitdiff_verify_name(line, patch->is_delete, patch->new_name, "new");
        return 0;
}

static int gitdiff_oldmode(const char *line, struct patch *patch)
{
        patch->old_mode = strtoul(line, NULL, 8);
        return 0;
}

static int gitdiff_newmode(const char *line, struct patch *patch)
{
        patch->new_mode = strtoul(line, NULL, 8);
        return 0;
}

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

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

static int gitdiff_copysrc(const char *line, struct patch *patch)
{
        patch->is_copy = 1;
        patch->old_name = find_name(line, NULL, 0, 0);
        return 0;
}

static int gitdiff_copydst(const char *line, struct patch *patch)
{
        patch->is_copy = 1;
        patch->new_name = find_name(line, NULL, 0, 0);
        return 0;
}

static int gitdiff_renamesrc(const char *line, struct patch *patch)
{
        patch->is_rename = 1;
        patch->old_name = find_name(line, NULL, 0, 0);
        return 0;
}

static int gitdiff_renamedst(const char *line, struct patch *patch)
{
        patch->is_rename = 1;
        patch->new_name = find_name(line, NULL, 0, 0);
        return 0;
}

static int gitdiff_similarity(const char *line, struct patch *patch)
{
        if ((patch->score = strtoul(line, NULL, 10)) == ULONG_MAX)
                patch->score = 0;
        return 0;
}

static int gitdiff_dissimilarity(const char *line, struct patch *patch)
{
        if ((patch->score = strtoul(line, NULL, 10)) == ULONG_MAX)
                patch->score = 0;
        return 0;
}

static int gitdiff_index(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;

        ptr = strchr(line, '.');
        if (!ptr || ptr[1] != '.' || 40 < ptr - line)
                return 0;
        len = ptr - line;
        memcpy(patch->old_sha1_prefix, line, len);
        patch->old_sha1_prefix[len] = 0;

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

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

        if (40 < len)
                return 0;
        memcpy(patch->new_sha1_prefix, line, len);
        patch->new_sha1_prefix[len] = 0;
        if (*ptr == ' ')
                patch->new_mode = patch->old_mode = strtoul(ptr+1, NULL, 8);
        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(const char *line, struct patch *patch)
{
        return -1;
}

static const char *stop_at_slash(const char *line, int llen)
{
        int i;

        for (i = 0; i < llen; i++) {
                int ch = line[i];
                if (ch == '/')
                        return line + i;
        }
        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(char *line, int llen)
{
        int len;
        const char *name;
        const char *second = NULL;

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

        if (*line == '"') {
                const char *cp;
                char *first = unquote_c_style(line, &second);
                if (!first)
                        return NULL;

                /* advance to the first slash */
                cp = stop_at_slash(first, strlen(first));
                if (!cp || cp == first) {
                        /* we do not accept absolute paths */
                free_first_and_fail:
                        free(first);
                        return NULL;
                }
                len = strlen(cp+1);
                memmove(first, cp+1, len+1); /* including NUL */

                /* 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_first_and_fail;
                if (*second == '"') {
                        char *sp = unquote_c_style(second, NULL);
                        if (!sp)
                                goto free_first_and_fail;
                        cp = stop_at_slash(sp, strlen(sp));
                        if (!cp || cp == sp) {
                        free_both_and_fail:
                                free(sp);
                                goto free_first_and_fail;
                        }
                        /* They must match, otherwise ignore */
                        if (strcmp(cp+1, first))
                                goto free_both_and_fail;
                        free(sp);
                        return first;
                }

                /* unquoted second */
                cp = stop_at_slash(second, line + llen - second);
                if (!cp || cp == second)
                        goto free_first_and_fail;
                cp++;
                if (line + llen - cp != len + 1 ||
                    memcmp(first, cp, len))
                        goto free_first_and_fail;
                return first;
        }

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

        name++;

        /* 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 == '"') {
                        const char *cp = second;
                        const char *np;
                        char *sp = unquote_c_style(second, NULL);

                        if (!sp)
                                return NULL;
                        np = stop_at_slash(sp, strlen(sp));
                        if (!np || np == sp) {
                        free_second_and_fail:
                                free(sp);
                                return NULL;
                        }
                        np++;
                        len = strlen(np);
                        if (len < cp - name &&
                            !strncmp(np, name, len) &&
                            isspace(name[len])) {
                                /* Good */
                                memmove(sp, np, len + 1);
                                return sp;
                        }
                        goto free_second_and_fail;
                }
        }

        /*
         * Accept a name only if it shows up twice, exactly the same
         * form.
         */
        for (len = 0 ; ; len++) {
                char c = name[len];

                switch (c) {
                default:
                        continue;
                case '\n':
                        return NULL;
                case '\t': case ' ':
                        second = name+len;
                        for (;;) {
                                char c = *second++;
                                if (c == '\n')
                                        return NULL;
                                if (c == '/')
                                        break;
                        }
                        if (second[len] == '\n' && !memcmp(name, second, len)) {
                                char *ret = xmalloc(len + 1);
                                memcpy(ret, name, len);
                                ret[len] = 0;
                                return ret;
                        }
                }
        }
        return NULL;
}

/* Verify that we recognize the lines following a git header */
static int parse_git_header(char *line, int len, unsigned int size, struct patch *patch)
{
        unsigned long offset;

        /* 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(line, len);

        line += len;
        size -= len;
        linenr++;
        for (offset = len ; size > 0 ; offset += len, size -= len, line += len, linenr++) {
                static const struct opentry {
                        const char *str;
                        int (*fn)(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);
                        if (len < oplen || memcmp(p->str, line, oplen))
                                continue;
                        if (p->fn(line + oplen, patch) < 0)
                                return offset;
                        break;
                }
        }

        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;
}

/*
 * Parse a unified diff fragment header of the
 * form "@@ -a,b +c,d @@"
 */
static int parse_fragment_header(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;
}

static int find_header(char *line, unsigned long size, int *hdrsize, struct patch *patch)
{
        unsigned long offset, len;

        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, 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", linenr, (int)len-1, line);
                }

                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_header(line, len, size, patch);
                        if (git_hdr_len <= len)
                                continue;
                        if (!patch->old_name && !patch->new_name) {
                                if (!patch->def_name)
                                        die("git diff header lacks filename information (line %d)", linenr);
                                patch->old_name = patch->new_name = patch->def_name;
                        }
                        *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
                 */
                nextlen = linelen(line + len, size - len);
                if (size < nextlen + 14 || memcmp("@@ -", line + len + nextlen, 4))
                        continue;

                /* Ok, we'll consider it a patch */
                parse_traditional_patch(line, line+len, patch);
                *hdrsize = len + nextlen;
                linenr += 2;
                return offset;
        }
        return -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(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;
        oldlines = fragment->oldlines;
        newlines = fragment->newlines;
        leading = 0;
        trailing = 0;

        if (patch->is_new < 0) {
                patch->is_new =  !oldlines;
                if (!oldlines)
                        patch->old_name = NULL;
        }
        if (patch->is_delete < 0) {
                patch->is_delete = !newlines;
                if (!newlines)
                        patch->new_name = NULL;
        }

        if (patch->is_new && oldlines)
                return error("new file depends on old contents");
        if (patch->is_delete != !newlines) {
                if (newlines)
                        return error("deleted file still has contents");
                fprintf(stderr, "** warning: file %s becomes empty but is not deleted\n", patch->new_name);
        }

        /* Parse the thing.. */
        line += len;
        size -= len;
        linenr++;
        added = deleted = 0;
        for (offset = len; size > 0; offset += len, size -= len, line += len, linenr++) {
                if (!oldlines && !newlines)
                        break;
                len = linelen(line, size);
                if (!len || line[len-1] != '\n')
                        return -1;
                switch (*line) {
                default:
                        return -1;
                case ' ':
                        oldlines--;
                        newlines--;
                        if (!deleted && !added)
                                leading++;
                        trailing++;
                        break;
                case '-':
                        deleted++;
                        oldlines--;
                        trailing = 0;
                        break;
                case '+':
                        /*
                         * We know len is at least two, since we have a '+' and
                         * we checked that the last character was a '\n' above.
                         * That is, an addition of an empty line would check
                         * the '+' here.  Sneaky...
                         */
                        if ((new_whitespace != nowarn_whitespace) &&
                            isspace(line[len-2])) {
                                whitespace_error++;
                                if (squelch_whitespace_errors &&
                                    squelch_whitespace_errors <
                                    whitespace_error)
                                        ;
                                else {
                                        fprintf(stderr, "Adds trailing whitespace.\n%s:%d:%.*s\n",
                                                patch_input_file,
                                                linenr, len-2, line+1);
                                }
                        }
                        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;
        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;
        return offset;
}

static int parse_single_patch(char *line, unsigned long size, struct patch *patch)
{
        unsigned long offset = 0;
        struct fragment **fragp = &patch->fragments;

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

                fragment = xcalloc(1, sizeof(*fragment));
                len = parse_fragment(line, size, patch, fragment);
                if (len <= 0)
                        die("corrupt patch at line %d", linenr);

                fragment->patch = line;
                fragment->size = len;

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

                offset += len;
                line += len;
                size -= len;
        }
        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 int parse_binary(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 "deflated
         * literal" or "deflated delta") and the length of data before
         * deflating; a sequence of 'length-byte' followed by base-85
         * encoded data follows.
         *
         * 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.
         * The end of binary is signaled with an empty line.
         */
        int llen, used;
        struct fragment *fragment;
        char *data = NULL;

        patch->fragments = fragment = xcalloc(1, sizeof(*fragment));

        /* Grab the type of patch */
        llen = linelen(buffer, size);
        used = llen;
        linenr++;

        if (!strncmp(buffer, "delta ", 6)) {
                patch->is_binary = BINARY_DELTA_DEFLATED;
                patch->deflate_origlen = strtoul(buffer + 6, NULL, 10);
        }
        else if (!strncmp(buffer, "literal ", 8)) {
                patch->is_binary = BINARY_LITERAL_DEFLATED;
                patch->deflate_origlen = strtoul(buffer + 8, NULL, 10);
        }
        else
                return error("unrecognized binary patch at line %d: %.*s",
                             linenr-1, llen-1, buffer);
        buffer += llen;
        while (1) {
                int byte_length, max_byte_length, newsize;
                llen = linelen(buffer, size);
                used += llen;
                linenr++;
                if (llen == 1)
                        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 = fragment->size + byte_length;
                data = xrealloc(data, newsize);
                if (decode_85(data + fragment->size,
                              buffer + 1,
                              byte_length))
                        goto corrupt;
                fragment->size = newsize;
                buffer += llen;
                size -= llen;
        }
        fragment->patch = data;
        return used;
 corrupt:
        return error("corrupt binary patch at line %d: %.*s",
                     linenr-1, llen-1, buffer);
}

static int parse_chunk(char *buffer, unsigned long size, struct patch *patch)
{
        int hdrsize, patchsize;
        int offset = find_header(buffer, size, &hdrsize, patch);

        if (offset < 0)
                return offset;

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

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

                /* Empty patch cannot be applied if:
                 * - it is a binary patch and we do not do binary_replace, or
                 * - text patch without metadata change
                 */
                if ((apply || check) &&
                    (patch->is_binary
                     ? !allow_binary_replacement
                     : !metadata_changes(patch)))
                        die("patch with only garbage at line %d", linenr);
        }

        return offset + hdrsize + patchsize;
}

#define swap(a,b) myswap((a),(b),sizeof(a))

#define myswap(a, b, size) do {         \
        unsigned char mytmp[size];      \
        memcpy(mytmp, &a, size);                \
        memcpy(&a, &b, size);           \
        memcpy(&b, mytmp, size);                \
} while (0)

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_sha1_prefix, p->new_sha1_prefix);

                for (; frag; frag = frag->next) {
                        swap(frag->newpos, frag->oldpos);
                        swap(frag->newlines, frag->oldlines);
                }
                p->is_reverse = !p->is_reverse;
        }
}

static const char pluses[] = "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++";
static const char minuses[]= "----------------------------------------------------------------------";

static void show_stats(struct patch *patch)
{
        const char *prefix = "";
        char *name = patch->new_name;
        char *qname = NULL;
        int len, max, add, del, total;

        if (!name)
                name = patch->old_name;

        if (0 < (len = quote_c_style(name, NULL, NULL, 0))) {
                qname = xmalloc(len + 1);
                quote_c_style(name, qname, NULL, 0);
                name = qname;
        }

        /*
         * "scale" the filename
         */
        len = strlen(name);
        max = max_len;
        if (max > 50)
                max = 50;
        if (len > max) {
                char *slash;
                prefix = "...";
                max -= 3;
                name += len - max;
                slash = strchr(name, '/');
                if (slash)
                        name = slash;
        }
        len = max;

        /*
         * scale the add/delete
         */
        max = max_change;
        if (max + len > 70)
                max = 70 - len;

        add = patch->lines_added;
        del = patch->lines_deleted;
        total = add + del;

        if (max_change > 0) {
                total = (total * max + max_change / 2) / max_change;
                add = (add * max + max_change / 2) / max_change;
                del = total - add;
        }
        if (patch->is_binary)
                printf(" %s%-*s |  Bin\n", prefix, len, name);
        else
                printf(" %s%-*s |%5d %.*s%.*s\n", prefix,
                       len, name, patch->lines_added + patch->lines_deleted,
                       add, pluses, del, minuses);
        if (qname)
                free(qname);
}

static int read_old_data(struct stat *st, const char *path, void *buf, unsigned long size)
{
        int fd;
        unsigned long got;

        switch (st->st_mode & S_IFMT) {
        case S_IFLNK:
                return readlink(path, buf, size);
        case S_IFREG:
                fd = open(path, O_RDONLY);
                if (fd < 0)
                        return error("unable to open %s", path);
                got = 0;
                for (;;) {
                        int ret = xread(fd, (char *) buf + got, size - got);
                        if (ret <= 0)
                                break;
                        got += ret;
                }
                close(fd);
                return got;

        default:
                return -1;
        }
}

static int find_offset(const char *buf, unsigned long size, const char *fragment, unsigned long fragsize, int line, int *lines)
{
        int i;
        unsigned long start, backwards, forwards;

        if (fragsize > size)
                return -1;

        start = 0;
        if (line > 1) {
                unsigned long offset = 0;
                i = line-1;
                while (offset + fragsize <= size) {
                        if (buf[offset++] == '\n') {
                                start = offset;
                                if (!--i)
                                        break;
                        }
                }
        }

        /* Exact line number? */
        if (!memcmp(buf + start, fragment, fragsize))
                return start;

        /*
         * There's probably some smart way to do this, but I'll leave
         * that to the smart and beautiful people. I'm simple and stupid.
         */
        backwards = start;
        forwards = start;
        for (i = 0; ; i++) {
                unsigned long try;
                int n;

                /* "backward" */
                if (i & 1) {
                        if (!backwards) {
                                if (forwards + fragsize > size)
                                        break;
                                continue;
                        }
                        do {
                                --backwards;
                        } while (backwards && buf[backwards-1] != '\n');
                        try = backwards;
                } else {
                        while (forwards + fragsize <= size) {
                                if (buf[forwards++] == '\n')
                                        break;
                        }
                        try = forwards;
                }

                if (try + fragsize > size)
                        continue;
                if (memcmp(buf + try, fragment, fragsize))
                        continue;
                n = (i >> 1)+1;
                if (i & 1)
                        n = -n;
                *lines = n;
                return try;
        }

        /*
         * We should start searching forward and backward.
         */
        return -1;
}

static void remove_first_line(const char **rbuf, int *rsize)
{
        const char *buf = *rbuf;
        int size = *rsize;
        unsigned long offset;
        offset = 0;
        while (offset <= size) {
                if (buf[offset++] == '\n')
                        break;
        }
        *rsize = size - offset;
        *rbuf = buf + offset;
}

static void remove_last_line(const char **rbuf, int *rsize)
{
        const char *buf = *rbuf;
        int size = *rsize;
        unsigned long offset;
        offset = size - 1;
        while (offset > 0) {
                if (buf[--offset] == '\n')
                        break;
        }
        *rsize = offset + 1;
}

struct buffer_desc {
        char *buffer;
        unsigned long size;
        unsigned long alloc;
};

static int apply_line(char *output, const char *patch, int plen)
{
        /* plen is number of bytes to be copied from patch,
         * starting at patch+1 (patch[0] is '+').  Typically
         * patch[plen] is '\n'.
         */
        int add_nl_to_tail = 0;
        if ((new_whitespace == strip_whitespace) &&
            1 < plen && isspace(patch[plen-1])) {
                if (patch[plen] == '\n')
                        add_nl_to_tail = 1;
                plen--;
                while (0 < plen && isspace(patch[plen]))
                        plen--;
                applied_after_stripping++;
        }
        memcpy(output, patch + 1, plen);
        if (add_nl_to_tail)
                output[plen++] = '\n';
        return plen;
}

static int apply_one_fragment(struct buffer_desc *desc, struct fragment *frag,
        int reverse, int inaccurate_eof)
{
        int match_beginning, match_end;
        char *buf = desc->buffer;
        const char *patch = frag->patch;
        int offset, size = frag->size;
        char *old = xmalloc(size);
        char *new = xmalloc(size);
        const char *oldlines, *newlines;
        int oldsize = 0, newsize = 0;
        unsigned long leading, trailing;
        int pos, lines;

        while (size > 0) {
                char first;
                int len = linelen(patch, size);
                int plen;

                if (!len)
                        break;

                /*
                 * "plen" is how much of the line we should use for
                 * the actual patch data. Normally we just remove the
                 * first character on the line, but if the line is
                 * followed by "\ No newline", then we also remove the
                 * last one (which is the newline, of course).
                 */
                plen = len-1;
                if (len < size && patch[len] == '\\')
                        plen--;
                first = *patch;
                if (reverse) {
                        if (first == '-')
                                first = '+';
                        else if (first == '+')
                                first = '-';
                }
                switch (first) {
                case ' ':
                case '-':
                        memcpy(old + oldsize, patch + 1, plen);
                        oldsize += plen;
                        if (first == '-')
                                break;
                /* Fall-through for ' ' */
                case '+':
                        if (first != '+' || !no_add)
                                newsize += apply_line(new + newsize, patch,
                                                      plen);
                        break;
                case '@': case '\\':
                        /* Ignore it, we already handled it */
                        break;
                default:
                        return -1;
                }
                patch += len;
                size -= len;
        }

        if (inaccurate_eof && oldsize > 0 && old[oldsize - 1] == '\n' &&
                        newsize > 0 && new[newsize - 1] == '\n') {
                oldsize--;
                newsize--;
        }

        oldlines = old;
        newlines = new;
        leading = frag->leading;
        trailing = frag->trailing;

        /*
         * If we don't have any leading/trailing data in the patch,
         * we want it to match at the beginning/end of the file.
         */
        match_beginning = !leading && (frag->oldpos == 1);
        match_end = !trailing;

        lines = 0;
        pos = frag->newpos;
        for (;;) {
                offset = find_offset(buf, desc->size, oldlines, oldsize, pos, &lines);
                if (match_end && offset + oldsize != desc->size)
                        offset = -1;
                if (match_beginning && offset)
                        offset = -1;
                if (offset >= 0) {
                        int diff = newsize - oldsize;
                        unsigned long size = desc->size + diff;
                        unsigned long alloc = desc->alloc;

                        /* Warn if it was necessary to reduce the number
                         * of context lines.
                         */
                        if ((leading != frag->leading) || (trailing != frag->trailing))
                                fprintf(stderr, "Context reduced to (%ld/%ld) to apply fragment at %d\n",
                                        leading, trailing, pos + lines);

                        if (size > alloc) {
                                alloc = size + 8192;
                                desc->alloc = alloc;
                                buf = xrealloc(buf, alloc);
                                desc->buffer = buf;
                        }
                        desc->size = size;
                        memmove(buf + offset + newsize, buf + offset + oldsize, size - offset - newsize);
                        memcpy(buf + offset, newlines, newsize);
                        offset = 0;

                        break;
                }

                /* Am I at my context limits? */
                if ((leading <= p_context) && (trailing <= p_context))
                        break;
                if (match_beginning || match_end) {
                        match_beginning = match_end = 0;
                        continue;
                }
                /* Reduce the number of context lines
                 * Reduce both leading and trailing if they are equal
                 * otherwise just reduce the larger context.
                 */
                if (leading >= trailing) {
                        remove_first_line(&oldlines, &oldsize);
                        remove_first_line(&newlines, &newsize);
                        pos--;
                        leading--;
                }
                if (trailing > leading) {
                        remove_last_line(&oldlines, &oldsize);
                        remove_last_line(&newlines, &newsize);
                        trailing--;
                }
        }

        free(old);
        free(new);
        return offset;
}

static char *inflate_it(const void *data, unsigned long size,
                        unsigned long inflated_size)
{
        z_stream 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;
        inflateInit(&stream);
        st = inflate(&stream, Z_FINISH);
        if ((st != Z_STREAM_END) || stream.total_out != inflated_size) {
                free(out);
                return NULL;
        }
        return out;
}

static int apply_binary_fragment(struct buffer_desc *desc, struct patch *patch)
{
        unsigned long dst_size;
        struct fragment *fragment = patch->fragments;
        void *data;
        void *result;

        /* Binary patch is irreversible */
        if (patch->is_reverse)
                return error("cannot reverse-apply a binary patch to '%s'",
                             patch->new_name
                             ? patch->new_name : patch->old_name);

        data = inflate_it(fragment->patch, fragment->size,
                          patch->deflate_origlen);
        if (!data)
                return error("corrupt patch data");
        switch (patch->is_binary) {
        case BINARY_DELTA_DEFLATED:
                result = patch_delta(desc->buffer, desc->size,
                                     data,
                                     patch->deflate_origlen,
                                     &dst_size);
                free(desc->buffer);
                desc->buffer = result;
                free(data);
                break;
        case BINARY_LITERAL_DEFLATED:
                free(desc->buffer);
                desc->buffer = data;
                dst_size = patch->deflate_origlen;
                break;
        }
        if (!desc->buffer)
                return -1;
        desc->size = desc->alloc = dst_size;
        return 0;
}

static int apply_binary(struct buffer_desc *desc, struct patch *patch)
{
        const char *name = patch->old_name ? patch->old_name : patch->new_name;
        unsigned char sha1[20];
        unsigned char hdr[50];
        int hdrlen;

        if (!allow_binary_replacement)
                return error("cannot apply binary patch to '%s' "
                             "without --allow-binary-replacement",
                             name);

        /* For safety, we require patch index line to contain
         * full 40-byte textual SHA1 for old and new, at least for now.
         */
        if (strlen(patch->old_sha1_prefix) != 40 ||
            strlen(patch->new_sha1_prefix) != 40 ||
            get_sha1_hex(patch->old_sha1_prefix, sha1) ||
            get_sha1_hex(patch->new_sha1_prefix, sha1))
                return error("cannot apply binary patch to '%s' "
                             "without full index line", name);

        if (patch->old_name) {
                /* See if the old one matches what the patch
                 * applies to.
                 */
                write_sha1_file_prepare(desc->buffer, desc->size,
                                        blob_type, sha1, hdr, &hdrlen);
                if (strcmp(sha1_to_hex(sha1), patch->old_sha1_prefix))
                        return error("the patch applies to '%s' (%s), "
                                     "which does not match the "
                                     "current contents.",
                                     name, sha1_to_hex(sha1));
        }
        else {
                /* Otherwise, the old one must be empty. */
                if (desc->size)
                        return error("the patch applies to an empty "
                                     "'%s' but it is not empty", name);
        }

        get_sha1_hex(patch->new_sha1_prefix, sha1);
        if (!memcmp(sha1, null_sha1, 20)) {
                free(desc->buffer);
                desc->alloc = desc->size = 0;
                desc->buffer = NULL;
                return 0; /* deletion patch */
        }

        if (has_sha1_file(sha1)) {
                /* We already have the postimage */
                char type[10];
                unsigned long size;

                free(desc->buffer);
                desc->buffer = read_sha1_file(sha1, type, &size);
                if (!desc->buffer)
                        return error("the necessary postimage %s for "
                                     "'%s' cannot be read",
                                     patch->new_sha1_prefix, name);
                desc->alloc = desc->size = size;
        }
        else {
                /* We have verified desc matches the preimage;
                 * apply the patch data to it, which is stored
                 * in the patch->fragments->{patch,size}.
                 */
                if (apply_binary_fragment(desc, patch))
                        return error("binary patch does not apply to '%s'",
                                     name);

                /* verify that the result matches */
                write_sha1_file_prepare(desc->buffer, desc->size, blob_type,
                                        sha1, hdr, &hdrlen);
                if (strcmp(sha1_to_hex(sha1), patch->new_sha1_prefix))
                        return error("binary patch to '%s' creates incorrect result", name);
        }

        return 0;
}

static int apply_fragments(struct buffer_desc *desc, struct patch *patch)
{
        struct fragment *frag = patch->fragments;
        const char *name = patch->old_name ? patch->old_name : patch->new_name;

        if (patch->is_binary)
                return apply_binary(desc, patch);

        while (frag) {
                if (apply_one_fragment(desc, frag, patch->is_reverse,
                                        patch->inaccurate_eof) < 0)
                        return error("patch failed: %s:%ld",
                                     name, frag->oldpos);
                frag = frag->next;
        }
        return 0;
}

static int apply_data(struct patch *patch, struct stat *st, struct cache_entry *ce)
{
        char *buf;
        unsigned long size, alloc;
        struct buffer_desc desc;

        size = 0;
        alloc = 0;
        buf = NULL;
        if (cached) {
                if (ce) {
                        char type[20];
                        buf = read_sha1_file(ce->sha1, type, &size);
                        if (!buf)
                                return error("read of %s failed",
                                             patch->old_name);
                        alloc = size;
                }
        }
        else if (patch->old_name) {
                size = st->st_size;
                alloc = size + 8192;
                buf = xmalloc(alloc);
                if (read_old_data(st, patch->old_name, buf, alloc) != size)
                        return error("read of %s failed", patch->old_name);
        }

        desc.size = size;
        desc.alloc = alloc;
        desc.buffer = buf;
        if (apply_fragments(&desc, patch) < 0)
                return -1;
        patch->result = desc.buffer;
        patch->resultsize = desc.size;

        if (patch->is_delete && patch->resultsize)
                return error("removal patch leaves file contents");

        return 0;
}

static int check_patch(struct patch *patch, struct patch *prev_patch)
{
        struct stat st;
        const char *old_name = patch->old_name;
        const char *new_name = patch->new_name;
        const char *name = old_name ? old_name : new_name;
        struct cache_entry *ce = NULL;
        int ok_if_exists;

        if (old_name) {
                int changed = 0;
                int stat_ret = 0;
                unsigned st_mode = 0;

                if (!cached)
                        stat_ret = lstat(old_name, &st);
                if (check_index) {
                        int pos = cache_name_pos(old_name, strlen(old_name));
                        if (pos < 0)
                                return error("%s: does not exist in index",
                                             old_name);
                        ce = active_cache[pos];
                        if (stat_ret < 0) {
                                struct checkout costate;
                                if (errno != ENOENT)
                                        return error("%s: %s", old_name,
                                                     strerror(errno));
                                /* checkout */
                                costate.base_dir = "";
                                costate.base_dir_len = 0;
                                costate.force = 0;
                                costate.quiet = 0;
                                costate.not_new = 0;
                                costate.refresh_cache = 1;
                                if (checkout_entry(ce,
                                                   &costate,
                                                   NULL) ||
                                    lstat(old_name, &st))
                                        return -1;
                        }
                        if (!cached)
                                changed = ce_match_stat(ce, &st, 1);
                        if (changed)
                                return error("%s: does not match index",
                                             old_name);
                        if (cached)
                                st_mode = ntohl(ce->ce_mode);
                }
                else if (stat_ret < 0)
                        return error("%s: %s", old_name, strerror(errno));

                if (!cached)
                        st_mode = ntohl(create_ce_mode(st.st_mode));

                if (patch->is_new < 0)
                        patch->is_new = 0;
                if (!patch->old_mode)
                        patch->old_mode = st_mode;
                if ((st_mode ^ patch->old_mode) & S_IFMT)
                        return error("%s: wrong type", old_name);
                if (st_mode != patch->old_mode)
                        fprintf(stderr, "warning: %s has type %o, expected %o\n",
                                old_name, st_mode, patch->old_mode);
        }

        if (new_name && prev_patch && prev_patch->is_delete &&
            !strcmp(prev_patch->old_name, new_name))
                /* A type-change diff is always split into a patch to
                 * delete old, immediately followed by a patch to
                 * create new (see diff.c::run_diff()); in such a case
                 * it is Ok that the entry to be deleted by the
                 * previous patch is still in the working tree and in
                 * the index.
                 */
                ok_if_exists = 1;
        else
                ok_if_exists = 0;

        if (new_name && (patch->is_new | patch->is_rename | patch->is_copy)) {
                if (check_index &&
                    cache_name_pos(new_name, strlen(new_name)) >= 0 &&
                    !ok_if_exists)
                        return error("%s: already exists in index", new_name);
                if (!cached) {
                        struct stat nst;
                        if (!lstat(new_name, &nst)) {
                                if (S_ISDIR(nst.st_mode) || ok_if_exists)
                                        ; /* ok */
                                else
                                        return error("%s: already exists in working directory", new_name);
                        }
                        else if ((errno != ENOENT) && (errno != ENOTDIR))
                                return error("%s: %s", new_name, strerror(errno));
                }
                if (!patch->new_mode) {
                        if (patch->is_new)
                                patch->new_mode = S_IFREG | 0644;
                        else
                                patch->new_mode = patch->old_mode;
                }
        }

        if (new_name && old_name) {
                int same = !strcmp(old_name, new_name);
                if (!patch->new_mode)
                        patch->new_mode = patch->old_mode;
                if ((patch->old_mode ^ patch->new_mode) & S_IFMT)
                        return error("new mode (%o) of %s does not match old mode (%o)%s%s",
                                patch->new_mode, new_name, patch->old_mode,
                                same ? "" : " of ", same ? "" : old_name);
        }

        if (apply_data(patch, &st, ce) < 0)
                return error("%s: patch does not apply", name);
        return 0;
}

static int check_patch_list(struct patch *patch)
{
        struct patch *prev_patch = NULL;
        int error = 0;

        for (prev_patch = NULL; patch ; patch = patch->next) {
                error |= check_patch(patch, prev_patch);
                prev_patch = patch;
        }
        return error;
}

static inline int is_null_sha1(const unsigned char *sha1)
{
        return !memcmp(sha1, null_sha1, 20);
}

static void show_index_list(struct patch *list)
{
        struct patch *patch;

        /* Once we start supporting the reverse patch, it may be
         * worth showing the new sha1 prefix, but until then...
         */
        for (patch = list; patch; patch = patch->next) {
                const unsigned char *sha1_ptr;
                unsigned char sha1[20];
                const char *name;

                name = patch->old_name ? patch->old_name : patch->new_name;
                if (patch->is_new)
                        sha1_ptr = null_sha1;
                else if (get_sha1(patch->old_sha1_prefix, sha1))
                        die("sha1 information is lacking or useless (%s).",
                            name);
                else
                        sha1_ptr = sha1;

                printf("%06o %s ",patch->old_mode, sha1_to_hex(sha1_ptr));
                if (line_termination && quote_c_style(name, NULL, NULL, 0))
                        quote_c_style(name, NULL, stdout, 0);
                else
                        fputs(name, stdout);
                putchar(line_termination);
        }
}

static void stat_patch_list(struct patch *patch)
{
        int files, adds, dels;

        for (files = adds = dels = 0 ; patch ; patch = patch->next) {
                files++;
                adds += patch->lines_added;
                dels += patch->lines_deleted;
                show_stats(patch);
        }

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

static void numstat_patch_list(struct patch *patch)
{
        for ( ; patch; patch = patch->next) {
                const char *name;
                name = patch->new_name ? patch->new_name : patch->old_name;
                printf("%d\t%d\t", patch->lines_added, patch->lines_deleted);
                if (line_termination && quote_c_style(name, NULL, NULL, 0))
                        quote_c_style(name, NULL, stdout, 0);
                else
                        fputs(name, stdout);
                putchar('\n');
        }
}

static void show_file_mode_name(const char *newdelete, unsigned int mode, const char *name)
{
        if (mode)
                printf(" %s mode %06o %s\n", newdelete, mode, name);
        else
                printf(" %s %s\n", newdelete, name);
}

static void show_mode_change(struct patch *p, int show_name)
{
        if (p->old_mode && p->new_mode && p->old_mode != p->new_mode) {
                if (show_name)
                        printf(" mode change %06o => %06o %s\n",
                               p->old_mode, p->new_mode, p->new_name);
                else
                        printf(" mode change %06o => %06o\n",
                               p->old_mode, p->new_mode);
        }
}

static void show_rename_copy(struct patch *p)
{
        const char *renamecopy = p->is_rename ? "rename" : "copy";
        const char *old, *new;

        /* Find common prefix */
        old = p->old_name;
        new = p->new_name;
        while (1) {
                const char *slash_old, *slash_new;
                slash_old = strchr(old, '/');
                slash_new = strchr(new, '/');
                if (!slash_old ||
                    !slash_new ||
                    slash_old - old != slash_new - new ||
                    memcmp(old, new, slash_new - new))
                        break;
                old = slash_old + 1;
                new = slash_new + 1;
        }
        /* p->old_name thru old is the common prefix, and old and new
         * through the end of names are renames
         */
        if (old != p->old_name)
                printf(" %s %.*s{%s => %s} (%d%%)\n", renamecopy,
                       (int)(old - p->old_name), p->old_name,
                       old, new, p->score);
        else
                printf(" %s %s => %s (%d%%)\n", renamecopy,
                       p->old_name, p->new_name, p->score);
        show_mode_change(p, 0);
}

static void summary_patch_list(struct patch *patch)
{
        struct patch *p;

        for (p = patch; p; p = p->next) {
                if (p->is_new)
                        show_file_mode_name("create", p->new_mode, p->new_name);
                else if (p->is_delete)
                        show_file_mode_name("delete", p->old_mode, p->old_name);
                else {
                        if (p->is_rename || p->is_copy)
                                show_rename_copy(p);
                        else {
                                if (p->score) {
                                        printf(" rewrite %s (%d%%)\n",
                                               p->new_name, p->score);
                                        show_mode_change(p, 0);
                                }
                                else
                                        show_mode_change(p, 1);
                        }
                }
        }
}

static void patch_stats(struct patch *patch)
{
        int lines = patch->lines_added + patch->lines_deleted;

        if (lines > max_change)
                max_change = lines;
        if (patch->old_name) {
                int len = quote_c_style(patch->old_name, NULL, NULL, 0);
                if (!len)
                        len = strlen(patch->old_name);
                if (len > max_len)
                        max_len = len;
        }
        if (patch->new_name) {
                int len = quote_c_style(patch->new_name, NULL, NULL, 0);
                if (!len)
                        len = strlen(patch->new_name);
                if (len > max_len)
                        max_len = len;
        }
}

static void remove_file(struct patch *patch)
{
        if (write_index) {
                if (remove_file_from_cache(patch->old_name) < 0)
                        die("unable to remove %s from index", patch->old_name);
                cache_tree_invalidate_path(active_cache_tree, patch->old_name);
        }
        if (!cached)
                unlink(patch->old_name);
}

static void add_index_file(const char *path, unsigned mode, void *buf, unsigned long size)
{
        struct stat st;
        struct cache_entry *ce;
        int namelen = strlen(path);
        unsigned ce_size = cache_entry_size(namelen);

        if (!write_index)
                return;

        ce = xcalloc(1, ce_size);
        memcpy(ce->name, path, namelen);
        ce->ce_mode = create_ce_mode(mode);
        ce->ce_flags = htons(namelen);
        if (!cached) {
                if (lstat(path, &st) < 0)
                        die("unable to stat newly created file %s", path);
                fill_stat_cache_info(ce, &st);
        }
        if (write_sha1_file(buf, size, blob_type, ce->sha1) < 0)
                die("unable to create backing store for newly created file %s", path);
        if (add_cache_entry(ce, ADD_CACHE_OK_TO_ADD) < 0)
                die("unable to add cache entry for %s", path);
}

static int try_create_file(const char *path, unsigned int mode, const char *buf, unsigned long size)
{
        int fd;

        if (S_ISLNK(mode))
                return symlink(buf, path);
        fd = open(path, O_CREAT | O_EXCL | O_WRONLY, (mode & 0100) ? 0777 : 0666);
        if (fd < 0)
                return -1;
        while (size) {
                int written = xwrite(fd, buf, size);
                if (written < 0)
                        die("writing file %s: %s", path, strerror(errno));
                if (!written)
                        die("out of space writing file %s", path);
                buf += written;
                size -= written;
        }
        if (close(fd) < 0)
                die("closing file %s: %s", path, strerror(errno));
        return 0;
}

/*
 * We optimistically assume that the directories exist,
 * which is true 99% of the time anyway. If they don't,
 * we create them and try again.
 */
static void create_one_file(char *path, unsigned mode, const char *buf, unsigned long size)
{
        if (cached)
                return;
        if (!try_create_file(path, mode, buf, size))
                return;

        if (errno == ENOENT) {
                if (safe_create_leading_directories(path))
                        return;
                if (!try_create_file(path, mode, buf, size))
                        return;
        }

        if (errno == EEXIST || errno == EACCES) {
                /* We may be trying to create a file where a directory
                 * used to be.
                 */
                struct stat st;
                errno = 0;
                if (!lstat(path, &st) && S_ISDIR(st.st_mode) && !rmdir(path))
                        errno = EEXIST;
        }

        if (errno == EEXIST) {
                unsigned int nr = getpid();

                for (;;) {
                        const char *newpath;
                        newpath = mkpath("%s~%u", path, nr);
                        if (!try_create_file(newpath, mode, buf, size)) {
                                if (!rename(newpath, path))
                                        return;
                                unlink(newpath);
                                break;
                        }
                        if (errno != EEXIST)
                                break;
                        ++nr;
                }
        }
        die("unable to write file %s mode %o", path, mode);
}

static void create_file(struct patch *patch)
{
        char *path = patch->new_name;
        unsigned mode = patch->new_mode;
        unsigned long size = patch->resultsize;
        char *buf = patch->result;

        if (!mode)
                mode = S_IFREG | 0644;
        create_one_file(path, mode, buf, size);
        add_index_file(path, mode, buf, size);
        cache_tree_invalidate_path(active_cache_tree, path);
}

/* phase zero is to remove, phase one is to create */
static void write_out_one_result(struct patch *patch, int phase)
{
        if (patch->is_delete > 0) {
                if (phase == 0)
                        remove_file(patch);
                return;
        }
        if (patch->is_new > 0 || patch->is_copy) {
                if (phase == 1)
                        create_file(patch);
                return;
        }
        /*
         * Rename or modification boils down to the same
         * thing: remove the old, write the new
         */
        if (phase == 0)
                remove_file(patch);
        if (phase == 1)
        create_file(patch);
}

static void write_out_results(struct patch *list, int skipped_patch)
{
        int phase;

        if (!list && !skipped_patch)
                die("No changes");

        for (phase = 0; phase < 2; phase++) {
                struct patch *l = list;
                while (l) {
                        write_out_one_result(l, phase);
                        l = l->next;
                }
        }
}

static struct lock_file lock_file;

static struct excludes {
        struct excludes *next;
        const char *path;
} *excludes;

static int use_patch(struct patch *p)
{
        const char *pathname = p->new_name ? p->new_name : p->old_name;
        struct excludes *x = excludes;
        while (x) {
                if (fnmatch(x->path, pathname, 0) == 0)
                        return 0;
                x = x->next;
        }
        if (0 < prefix_length) {
                int pathlen = strlen(pathname);
                if (pathlen <= prefix_length ||
                    memcmp(prefix, pathname, prefix_length))
                        return 0;
        }
        return 1;
}

static int apply_patch(int fd, const char *filename,
                int reverse, int inaccurate_eof)
{
        unsigned long offset, size;
        char *buffer = read_patch_file(fd, &size);
        struct patch *list = NULL, **listp = &list;
        int skipped_patch = 0;

        patch_input_file = filename;
        if (!buffer)
                return -1;
        offset = 0;
        while (size > 0) {
                struct patch *patch;
                int nr;

                patch = xcalloc(1, sizeof(*patch));
                patch->inaccurate_eof = inaccurate_eof;
                nr = parse_chunk(buffer + offset, size, patch);
                if (nr < 0)
                        break;
                if (reverse)
                        reverse_patches(patch);
                if (use_patch(patch)) {
                        patch_stats(patch);
                        *listp = patch;
                        listp = &patch->next;
                } else {
                        /* perhaps free it a bit better? */
                        free(patch);
                        skipped_patch++;
                }
                offset += nr;
                size -= nr;
        }

        if (whitespace_error && (new_whitespace == error_on_whitespace))
                apply = 0;

        write_index = check_index && apply;
        if (write_index && newfd < 0) {
                newfd = hold_lock_file_for_update(&lock_file,
                                                  get_index_file());
                if (newfd < 0)
                        die("unable to create new index file");
        }
        if (check_index) {
                if (read_cache() < 0)
                        die("unable to read index file");
        }

        if ((check || apply) && check_patch_list(list) < 0)
                exit(1);

        if (apply)
                write_out_results(list, skipped_patch);

        if (show_index_info)
                show_index_list(list);

        if (diffstat)
                stat_patch_list(list);

        if (numstat)
                numstat_patch_list(list);

        if (summary)
                summary_patch_list(list);

        free(buffer);
        return 0;
}

static int git_apply_config(const char *var, const char *value)
{
        if (!strcmp(var, "apply.whitespace")) {
                apply_default_whitespace = strdup(value);
                return 0;
        }
        return git_default_config(var, value);
}


int cmd_apply(int argc, const char **argv, const char *prefix)
{
        int i;
        int read_stdin = 1;
        int reverse = 0;
        int inaccurate_eof = 0;

        const char *whitespace_option = NULL;

        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
                char *end;
                int fd;

                if (!strcmp(arg, "-")) {
                        apply_patch(0, "<stdin>", reverse, inaccurate_eof);
                        read_stdin = 0;
                        continue;
                }
                if (!strncmp(arg, "--exclude=", 10)) {
                        struct excludes *x = xmalloc(sizeof(*x));
                        x->path = arg + 10;
                        x->next = excludes;
                        excludes = x;
                        continue;
                }
                if (!strncmp(arg, "-p", 2)) {
                        p_value = atoi(arg + 2);
                        continue;
                }
                if (!strcmp(arg, "--no-add")) {
                        no_add = 1;
                        continue;
                }
                if (!strcmp(arg, "--stat")) {
                        apply = 0;
                        diffstat = 1;
                        continue;
                }
                if (!strcmp(arg, "--allow-binary-replacement") ||
                    !strcmp(arg, "--binary")) {
                        allow_binary_replacement = 1;
                        continue;
                }
                if (!strcmp(arg, "--numstat")) {
                        apply = 0;
                        numstat = 1;
                        continue;
                }
                if (!strcmp(arg, "--summary")) {
                        apply = 0;
                        summary = 1;
                        continue;
                }
                if (!strcmp(arg, "--check")) {
                        apply = 0;
                        check = 1;
                        continue;
                }
                if (!strcmp(arg, "--index")) {
                        check_index = 1;
                        continue;
                }
                if (!strcmp(arg, "--cached")) {
                        check_index = 1;
                        cached = 1;
                        continue;
                }
                if (!strcmp(arg, "--apply")) {
                        apply = 1;
                        continue;
                }
                if (!strcmp(arg, "--index-info")) {
                        apply = 0;
                        show_index_info = 1;
                        continue;
                }
                if (!strcmp(arg, "-z")) {
                        line_termination = 0;
                        continue;
                }
                if (!strncmp(arg, "-C", 2)) {
                        p_context = strtoul(arg + 2, &end, 0);
                        if (*end != '\0')
                                die("unrecognized context count '%s'", arg + 2);
                        continue;
                }
                if (!strncmp(arg, "--whitespace=", 13)) {
                        whitespace_option = arg + 13;
                        parse_whitespace_option(arg + 13);
                        continue;
                }
                if (!strcmp(arg, "-R") || !strcmp(arg, "--reverse")) {
                        reverse = 1;
                        continue;
                }
                if (!strcmp(arg, "--inaccurate-eof")) {
                        inaccurate_eof = 1;
                        continue;
                }

                if (check_index && prefix_length < 0) {
                        prefix = setup_git_directory();
                        prefix_length = prefix ? strlen(prefix) : 0;
                        git_config(git_apply_config);
                        if (!whitespace_option && apply_default_whitespace)
                                parse_whitespace_option(apply_default_whitespace);
                }
                if (0 < prefix_length)
                        arg = prefix_filename(prefix, prefix_length, arg);

                fd = open(arg, O_RDONLY);
                if (fd < 0)
                        usage(apply_usage);
                read_stdin = 0;
                set_default_whitespace_mode(whitespace_option);
                apply_patch(fd, arg, reverse, inaccurate_eof);
                close(fd);
        }
        set_default_whitespace_mode(whitespace_option);
        if (read_stdin)
                apply_patch(0, "<stdin>", reverse, inaccurate_eof);
        if (whitespace_error) {
                if (squelch_whitespace_errors &&
                    squelch_whitespace_errors < whitespace_error) {
                        int squelched =
                                whitespace_error - squelch_whitespace_errors;
                        fprintf(stderr, "warning: squelched %d whitespace error%s\n",
                                squelched,
                                squelched == 1 ? "" : "s");
                }
                if (new_whitespace == error_on_whitespace)
                        die("%d line%s add%s trailing whitespaces.",
                            whitespace_error,
                            whitespace_error == 1 ? "" : "s",
                            whitespace_error == 1 ? "s" : "");
                if (applied_after_stripping)
                        fprintf(stderr, "warning: %d line%s applied after"
                                " stripping trailing whitespaces.\n",
                                applied_after_stripping,
                                applied_after_stripping == 1 ? "" : "s");
                else if (whitespace_error)
                        fprintf(stderr, "warning: %d line%s add%s trailing"
                                " whitespaces.\n",
                                whitespace_error,
                                whitespace_error == 1 ? "" : "s",
                                whitespace_error == 1 ? "s" : "");
        }

        if (write_index) {
                if (write_cache(newfd, active_cache, active_nr) ||
                    close(newfd) || commit_lock_file(&lock_file))
                        die("Unable to write new index file");
        }

        return 0;
}