Don't use -C in "git diff"
[gitweb.git] / apply.c
diff --git a/apply.c b/apply.c
index 3c3ec905743d3aeaa0f33bbea11db4824d5129dc..c0cd1520db6ef1036678046fc5c8ada174155c49 100644 (file)
--- a/apply.c
+++ b/apply.c
 #include "cache.h"
 
 // We default to the merge behaviour, since that's what most people would
-// expect
+// expect.
+//
+//  --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
+//  --show-files shows the directory changes
+//
 static int merge_patch = 1;
-static const char apply_usage[] = "git-apply <patch>";
+static int check_index = 0;
+static int write_index = 0;
+static int diffstat = 0;
+static int check = 0;
+static int apply = 1;
+static int show_files = 0;
+static const char apply_usage[] = "git-apply [--stat] [--check] [--show-files] <patch>";
 
 /*
  * For "diff-stat" like behaviour, we keep track of the biggest change
@@ -34,7 +46,6 @@ static int max_change, max_len;
  * things are flags, where -1 means "don't know yet".
  */
 static int linenr = 1;
-static char *def_name = NULL;
 
 struct fragment {
        unsigned long oldpos, oldlines;
@@ -45,11 +56,13 @@ struct fragment {
 };
 
 struct patch {
-       char *new_name, *old_name;
+       char *new_name, *old_name, *def_name;
        unsigned int old_mode, new_mode;
        int is_rename, is_copy, is_new, is_delete;
        int lines_added, lines_deleted;
        struct fragment *fragments;
+       char *result;
+       unsigned long resultsize;
        struct patch *next;
 };
 
@@ -91,7 +104,7 @@ static void *read_patch_file(int fd, unsigned long *sizep)
        return buffer;
 }
 
-static unsigned long linelen(char *buffer, unsigned long size)
+static unsigned long linelen(const char *buffer, unsigned long size)
 {
        unsigned long len = 0;
        while (size--) {
@@ -107,9 +120,8 @@ static int is_dev_null(const char *str)
        return !memcmp("/dev/null", str, 9) && isspace(str[9]);
 }
 
-#define TERM_EXIST     1
-#define TERM_SPACE     2
-#define TERM_TAB       4
+#define TERM_SPACE     1
+#define TERM_TAB       2
 
 static int name_terminate(const char *name, int namelen, int c, int terminate)
 {
@@ -118,13 +130,6 @@ static int name_terminate(const char *name, int namelen, int c, int terminate)
        if (c == '\t' && !(terminate & TERM_TAB))
                return 0;
 
-       /*
-        * Do we want an existing name? Return false and
-        * continue if it's not there.
-        */
-       if (terminate & TERM_EXIST)
-               return cache_name_pos(name, namelen) >= 0;
-
        return 1;
 }
 
@@ -191,16 +196,16 @@ static void parse_traditional_patch(const char *first, const char *second, struc
        if (is_dev_null(first)) {
                patch->is_new = 1;
                patch->is_delete = 0;
-               name = find_name(second, def_name, p_value, TERM_SPACE | TERM_TAB);
+               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, def_name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
+               name = find_name(first, NULL, p_value, TERM_SPACE | TERM_TAB);
                patch->old_name = name;
        } else {
-               name = find_name(first, def_name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
-               name = find_name(second, name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
+               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)
@@ -283,12 +288,14 @@ static int gitdiff_newmode(const char *line, struct patch *patch)
 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);
 }
 
@@ -325,6 +332,11 @@ static int gitdiff_similarity(const char *line, struct patch *patch)
        return 0;
 }
 
+static int gitdiff_dissimilarity(const char *line, struct patch *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.
@@ -334,6 +346,61 @@ static int gitdiff_unrecognized(const char *line, struct patch *patch)
        return -1;
 }
 
+static char *git_header_name(char *line)
+{
+       int len;
+       char *name, *second;
+
+       /*
+        * Find the first '/'
+        */
+       name = line;
+       for (;;) {
+               char c = *name++;
+               if (c == '\n')
+                       return NULL;
+               if (c == '/')
+                       break;
+       }
+
+       /*
+        * We don't accept absolute paths (/dev/null) as possibly valid
+        */
+       if (name == line+1)
+               return NULL;
+
+       /*
+        * 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':
+                       break;
+               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)
 {
@@ -343,6 +410,14 @@ static int parse_git_header(char *line, int len, unsigned int size, struct patch
        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 + strlen("diff --git "));
+
        line += len;
        size -= len;
        linenr++;
@@ -360,9 +435,12 @@ static int parse_git_header(char *line, int len, unsigned int size, struct patch
                        { "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 },
                        { "", gitdiff_unrecognized },
                };
                int i;
@@ -384,9 +462,19 @@ static int parse_git_header(char *line, int len, unsigned int size, struct patch
        return offset;
 }
 
-static int parse_num(const char *line, int len, int offset, const char *expect, unsigned long *p)
+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)
@@ -394,16 +482,25 @@ static int parse_num(const char *line, int len, int offset, const char *expect,
        line += offset;
        len -= offset;
 
-       if (!isdigit(*line))
+       digits = parse_num(line, p1);
+       if (!digits)
                return -1;
-       *p = strtoul(line, &ptr, 10);
-
-       digits = ptr - line;
 
        offset += digits;
        line += digits;
        len -= digits;
 
+       *p2 = *p1;
+       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;
@@ -425,10 +522,8 @@ static int parse_fragment_header(char *line, int len, struct fragment *fragment)
                return -1;
 
        /* Figure out the number of lines in a fragment */
-       offset = parse_num(line, len, 4, ",", &fragment->oldpos);
-       offset = parse_num(line, len, offset, " +", &fragment->oldlines);
-       offset = parse_num(line, len, offset, ",", &fragment->newpos);
-       offset = parse_num(line, len, offset, " @@", &fragment->newlines);
+       offset = parse_range(line, len, 4, " +", &fragment->oldpos, &fragment->oldlines);
+       offset = parse_range(line, len, offset, " @@", &fragment->newpos, &fragment->newlines);
 
        return offset;
 }
@@ -473,9 +568,10 @@ static int find_header(char *line, unsigned long size, int *hdrsize, struct patc
                 */
                if (!memcmp("diff --git ", line, 11)) {
                        int git_hdr_len = parse_git_header(line, len, size, patch);
-                       if (git_hdr_len < 0)
+                       if (git_hdr_len <= len)
                                continue;
-
+                       if (!patch->old_name && !patch->new_name)
+                               die("git diff header lacks filename information (line %d)", linenr);
                        *hdrsize = git_hdr_len;
                        return offset;
                }
@@ -513,7 +609,7 @@ static int parse_fragment(char *line, unsigned long size, struct patch *patch, s
 {
        int added, deleted;
        int len = linelen(line, size), offset;
-       unsigned long pos[4], oldlines, newlines;
+       unsigned long oldlines, newlines;
 
        offset = parse_fragment_header(line, len, fragment);
        if (offset < 0)
@@ -521,10 +617,24 @@ static int parse_fragment(char *line, unsigned long size, struct patch *patch, s
        oldlines = fragment->oldlines;
        newlines = fragment->newlines;
 
-       if (patch->is_new < 0 && (pos[0] || oldlines))
-               patch->is_new = 0;
-       if (patch->is_delete < 0 && (pos[1] || newlines))
-               patch->is_delete = 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;
@@ -552,6 +662,11 @@ static int parse_fragment(char *line, unsigned long size, struct patch *patch, s
                        added++;
                        newlines--;
                        break;
+               /* We allow "\ No newline at end of file" */
+               case '\\':
+                       if (len < 12 || memcmp(line, "\\ No newline", 12))
+                               return -1;
+                       break;
                }
        }
        patch->lines_added += added;
@@ -606,7 +721,7 @@ const char minuses[]= "---------------------------------------------------------
 static void show_stats(struct patch *patch)
 {
        char *name = patch->old_name;
-       int len, max, add, del;
+       int len, max, add, del, total;
 
        if (!name)
                name = patch->new_name;
@@ -628,41 +743,348 @@ static void show_stats(struct patch *patch)
        max = max_change;
        if (max + len > 70)
                max = 70 - len;
-       
-       add = (patch->lines_added * max + max_change/2) / max_change;
-       del = (patch->lines_deleted * max + max_change/2) / max_change;
+
+       add = patch->lines_added;
+       del = patch->lines_deleted;
+       total = add + del;
+
+       total = (total * max + max_change / 2) / max_change;
+       add = (add * max + max_change / 2) / max_change;
+       del = total - add;
        printf(" %-*s |%5d %.*s%.*s\n",
                len, name, patch->lines_added + patch->lines_deleted,
                add, pluses, del, minuses);
 }
 
-static void apply_patch_list(struct patch *patch)
+static int read_old_data(struct stat *st, const char *path, void *buf, unsigned long size)
 {
-       int files, adds, dels;
+       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 = read(fd, buf + got, size - got);
+                       if (ret < 0) {
+                               if (errno == EAGAIN)
+                                       continue;
+                               break;
+                       }
+                       if (!ret)
+                               break;
+                       got += ret;
+               }
+               close(fd);
+               return got;
 
-       files = adds = dels = 0;
-       if (!patch)
-               die("no patch found");
-       do {
-               const char *old_name = patch->old_name;
-               const char *new_name = patch->new_name;
-
-               if (old_name) {
-                       if (cache_name_pos(old_name, strlen(old_name)) < 0)
-                               die("file %s does not exist", old_name);
-                       if (patch->is_new < 0)
-                               patch->is_new = 0;
+       default:
+               return -1;
+       }
+}
+
+static int find_offset(const char *buf, unsigned long size, const char *fragment, unsigned long fragsize, int line)
+{
+       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;
+                       }
                }
-               if (new_name && (patch->is_new | patch->is_rename | patch->is_copy)) {
-                       if (cache_name_pos(new_name, strlen(new_name)) >= 0)
-                               die("file %s already exists", new_name);
+       }
+
+       /* 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;
+               fprintf(stderr, "Fragment applied at offset %d\n", n);
+               return try;
+       }
+
+       /*
+        * We should start searching forward and backward.
+        */
+       return -1;
+}
+
+struct buffer_desc {
+       char *buffer;
+       unsigned long size;
+       unsigned long alloc;
+};
+
+static int apply_one_fragment(struct buffer_desc *desc, struct fragment *frag)
+{
+       char *buf = desc->buffer;
+       const char *patch = frag->patch;
+       int offset, size = frag->size;
+       char *old = xmalloc(size);
+       char *new = xmalloc(size);
+       int oldsize = 0, newsize = 0;
+
+       while (size > 0) {
+               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--;
+               switch (*patch) {
+               case ' ':
+               case '-':
+                       memcpy(old + oldsize, patch + 1, plen);
+                       oldsize += plen;
+                       if (*patch == '-')
+                               break;
+               /* Fall-through for ' ' */
+               case '+':
+                       memcpy(new + newsize, patch + 1, plen);
+                       newsize += plen;
+                       break;
+               case '@': case '\\':
+                       /* Ignore it, we already handled it */
+                       break;
+               default:
+                       return -1;
+               }
+               patch += len;
+               size -= len;
+       }
+
+       offset = find_offset(buf, desc->size, old, oldsize, frag->newpos);
+       if (offset >= 0) {
+               int diff = newsize - oldsize;
+               unsigned long size = desc->size + diff;
+               unsigned long alloc = desc->alloc;
+
+               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, new, newsize);
+               offset = 0;
+       }
+
+       free(old);
+       free(new);
+       return offset;
+}
+
+static int apply_fragments(struct buffer_desc *desc, struct patch *patch)
+{
+       struct fragment *frag = patch->fragments;
+
+       while (frag) {
+               if (apply_one_fragment(desc, frag) < 0)
+                       return error("patch failed: %s:%d", patch->old_name, frag->oldpos);
+               frag = frag->next;
+       }
+       return 0;
+}
+
+static int apply_data(struct patch *patch, struct stat *st)
+{
+       char *buf;
+       unsigned long size, alloc;
+       struct buffer_desc desc;
+
+       size = 0;
+       alloc = 0;
+       buf = NULL;
+       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 stat st;
+       const char *old_name = patch->old_name;
+       const char *new_name = patch->new_name;
+
+       if (old_name) {
+               int changed;
+
+               if (lstat(old_name, &st) < 0)
+                       return error("%s: %s", old_name, strerror(errno));
+               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);
+                       changed = ce_match_stat(active_cache[pos], &st);
+                       if (changed)
+                               return error("%s: does not match index", old_name);
+               }
+               if (patch->is_new < 0)
+                       patch->is_new = 0;
+               st.st_mode = ntohl(create_ce_mode(st.st_mode));
+               if (!patch->old_mode)
+                       patch->old_mode = st.st_mode;
+               if ((st.st_mode ^ patch->old_mode) & S_IFMT)
+                       return error("%s: wrong type", old_name);
+               if (st.st_mode != patch->old_mode)
+                       fprintf(stderr, "warning: %s has type %o, expected %o\n",
+                               old_name, st.st_mode, patch->old_mode);
+       }
+
+       if (new_name && (patch->is_new | patch->is_rename | patch->is_copy)) {
+               if (check_index && cache_name_pos(new_name, strlen(new_name)) >= 0)
+                       return error("%s: already exists in index", new_name);
+               if (!lstat(new_name, &st))
+                       return error("%s: already exists in working directory", new_name);
+               if (errno != ENOENT)
+                       return error("%s: %s", new_name, strerror(errno));
+               if (!patch->new_mode)
+                       patch->new_mode = S_IFREG | 0644;
+       }
+
+       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) < 0)
+               return error("%s: patch does not apply", old_name);
+       return 0;
+}
+
+static int check_patch_list(struct patch *patch)
+{
+       int error = 0;
+
+       for (;patch ; patch = patch->next)
+               error |= check_patch(patch);
+       return error;
+}
+
+static void show_file(int c, unsigned int mode, const char *name)
+{
+       printf("%c %o %s\n", c, mode, name);
+}
+
+static void show_file_list(struct patch *patch)
+{
+       for (;patch ; patch = patch->next) {
+               if (patch->is_rename) {
+                       show_file('-', patch->old_mode, patch->old_name);
+                       show_file('+', patch->new_mode, patch->new_name);
+                       continue;
+               }
+               if (patch->is_copy || patch->is_new) {
+                       show_file('+', patch->new_mode, patch->new_name);
+                       continue;
+               }
+               if (patch->is_delete) {
+                       show_file('-', patch->old_mode, patch->old_name);
+                       continue;
+               }
+               if (patch->old_mode && patch->new_mode && patch->old_mode != patch->new_mode) {
+                       printf("M %o:%o %s\n", patch->old_mode, patch->new_mode, patch->old_name);
+                       continue;
+               }
+               printf("M %o %s\n", patch->old_mode, patch->old_name);
+       }
+}
+
+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);
-       } while ((patch = patch->next) != NULL);
+       }
+
        printf(" %d files changed, %d insertions(+), %d deletions(-)\n", files, adds, dels);
 }
 
@@ -684,8 +1106,106 @@ static void patch_stats(struct patch *patch)
        }
 }
 
+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);
+       }
+       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 = xmalloc(ce_size);
+       memset(ce, 0, ce_size);
+       memcpy(ce->name, path, namelen);
+       ce->ce_mode = create_ce_mode(mode);
+       ce->ce_flags = htons(namelen);
+       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", 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 void create_file(struct patch *patch)
+{
+       const 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;
+       if (S_ISREG(mode)) {
+               int fd;
+               mode = (mode & 0100) ? 0777 : 0666;
+               fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, mode);
+               if (fd < 0)
+                       die("unable to create file %s (%s)", path, strerror(errno));
+               if (write(fd, buf, size) != size)
+                       die("unable to write file %s", path);
+               close(fd);
+               add_index_file(path, mode, buf, size);
+               return;
+       }
+       if (S_ISLNK(mode)) {
+               if (size && buf[size-1] == '\n')
+                       size--;
+               buf[size] = 0;
+               if (symlink(buf, path) < 0)
+                       die("unable to write symlink %s", path);
+               add_index_file(path, mode, buf, size);
+               return;
+       }
+       die("unable to write file mode %o", mode);
+}
+
+static void write_out_one_result(struct patch *patch)
+{
+       if (patch->is_delete > 0) {
+               remove_file(patch);
+               return;
+       }
+       if (patch->is_new > 0 || patch->is_copy) {
+               create_file(patch);
+               return;
+       }
+       /*
+        * Rename or modification boils down to the same
+        * thing: remove the old, write the new
+        */
+       remove_file(patch);
+       create_file(patch);
+}
+
+static void write_out_results(struct patch *list)
+{
+       if (!list)
+               die("No changes");
+
+       while (list) {
+               write_out_one_result(list);
+               list = list->next;
+       }
+}
+
+static struct cache_file cache_file;
+
 static int apply_patch(int fd)
 {
+       int newfd;
        unsigned long offset, size;
        char *buffer = read_patch_file(fd, &size);
        struct patch *list = NULL, **listp = &list;
@@ -709,7 +1229,32 @@ static int apply_patch(int fd)
                size -= nr;
        }
 
-       apply_patch_list(list);
+       newfd = -1;
+       write_index = check_index && apply;
+       if (write_index)
+               newfd = hold_index_file_for_update(&cache_file, get_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);
+
+       if (write_index) {
+               if (write_cache(newfd, active_cache, active_nr) ||
+                   commit_index_file(&cache_file))
+                       die("Unable to write new cachefile");
+       }
+
+       if (show_files)
+               show_file_list(list);
+
+       if (diffstat)
+               stat_patch_list(list);
 
        free(buffer);
        return 0;
@@ -720,9 +1265,6 @@ int main(int argc, char **argv)
        int i;
        int read_stdin = 1;
 
-       if (read_cache() < 0)
-               die("unable to read index file");
-
        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
                int fd;
@@ -736,6 +1278,24 @@ int main(int argc, char **argv)
                        merge_patch = 0;
                        continue;
                }
+               if (!strcmp(arg, "--stat")) {
+                       apply = 0;
+                       diffstat = 1;
+                       continue;
+               }
+               if (!strcmp(arg, "--check")) {
+                       apply = 0;
+                       check = 1;
+                       continue;
+               }
+               if (!strcmp(arg, "--index")) {
+                       check_index = 1;
+                       continue;
+               }
+               if (!strcmp(arg, "--show-files")) {
+                       show_files = 1;
+                       continue;
+               }
                fd = open(arg, O_RDONLY);
                if (fd < 0)
                        usage(apply_usage);