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![Linus Torvalds](/assets/img/avatar_default.png)
Make it a clear two-phase thing: first a read-only parse of the patch itself (which is independent of any current index information), and then the second phase actually uses the patch. The second phase might not be a real apply, it could be just a diffstat, for example. Which is trivial to do once the patch is parsed.
688 lines
16 KiB
C
688 lines
16 KiB
C
/*
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* apply.c
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*
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* Copyright (C) Linus Torvalds, 2005
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*
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* This applies patches on top of some (arbitrary) version of the SCM.
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*
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* NOTE! It does all its work in the index file, and only cares about
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* the files in the working directory if you tell it to "merge" the
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* patch apply.
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*
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* Even when merging it always takes the source from the index, and
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* uses the working tree as a "branch" for a 3-way merge.
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*/
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#include <ctype.h>
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#include "cache.h"
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// We default to the merge behaviour, since that's what most people would
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// expect
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static int merge_patch = 1;
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static const char apply_usage[] = "git-apply <patch>";
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/*
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* Various "current state", notably line numbers and what
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* file (and how) we're patching right now.. The "is_xxxx"
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* things are flags, where -1 means "don't know yet".
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*/
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static int linenr = 1;
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static char *def_name = NULL;
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struct fragment {
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unsigned long oldpos, oldlines;
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unsigned long newpos, newlines;
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const char *patch;
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int size;
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struct fragment *next;
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};
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struct patch {
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char *new_name, *old_name;
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unsigned int old_mode, new_mode;
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int is_rename, is_copy, is_new, is_delete;
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struct fragment *fragments;
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struct patch *next;
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};
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#define CHUNKSIZE (8192)
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#define SLOP (16)
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static void *read_patch_file(int fd, unsigned long *sizep)
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{
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unsigned long size = 0, alloc = CHUNKSIZE;
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void *buffer = xmalloc(alloc);
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for (;;) {
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int nr = alloc - size;
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if (nr < 1024) {
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alloc += CHUNKSIZE;
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buffer = xrealloc(buffer, alloc);
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nr = alloc - size;
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}
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nr = read(fd, buffer + size, nr);
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if (!nr)
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break;
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if (nr < 0) {
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if (errno == EAGAIN)
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continue;
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die("git-apply: read returned %s", strerror(errno));
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}
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size += nr;
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}
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*sizep = size;
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/*
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* Make sure that we have some slop in the buffer
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* so that we can do speculative "memcmp" etc, and
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* see to it that it is NUL-filled.
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*/
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if (alloc < size + SLOP)
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buffer = xrealloc(buffer, size + SLOP);
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memset(buffer + size, 0, SLOP);
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return buffer;
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}
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static unsigned long linelen(char *buffer, unsigned long size)
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{
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unsigned long len = 0;
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while (size--) {
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len++;
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if (*buffer++ == '\n')
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break;
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}
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return len;
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}
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static int is_dev_null(const char *str)
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{
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return !memcmp("/dev/null", str, 9) && isspace(str[9]);
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}
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#define TERM_EXIST 1
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#define TERM_SPACE 2
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#define TERM_TAB 4
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static int name_terminate(const char *name, int namelen, int c, int terminate)
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{
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if (c == ' ' && !(terminate & TERM_SPACE))
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return 0;
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if (c == '\t' && !(terminate & TERM_TAB))
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return 0;
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/*
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* Do we want an existing name? Return false and
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* continue if it's not there.
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*/
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if (terminate & TERM_EXIST)
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return cache_name_pos(name, namelen) >= 0;
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return 1;
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}
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static char * find_name(const char *line, char *def, int p_value, int terminate)
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{
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int len;
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const char *start = line;
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char *name;
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for (;;) {
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char c = *line;
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if (isspace(c)) {
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if (c == '\n')
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break;
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if (name_terminate(start, line-start, c, terminate))
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break;
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}
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line++;
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if (c == '/' && !--p_value)
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start = line;
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}
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if (!start)
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return def;
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len = line - start;
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if (!len)
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return def;
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/*
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* Generally we prefer the shorter name, especially
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* if the other one is just a variation of that with
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* something else tacked on to the end (ie "file.orig"
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* or "file~").
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*/
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if (def) {
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int deflen = strlen(def);
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if (deflen < len && !strncmp(start, def, deflen))
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return def;
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}
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name = xmalloc(len + 1);
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memcpy(name, start, len);
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name[len] = 0;
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free(def);
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return name;
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}
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/*
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* Get the name etc info from the --/+++ lines of a traditional patch header
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*
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* NOTE! This hardcodes "-p1" behaviour in filename detection.
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*
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* FIXME! The end-of-filename heuristics are kind of screwy. For existing
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* files, we can happily check the index for a match, but for creating a
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* new file we should try to match whatever "patch" does. I have no idea.
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*/
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static void parse_traditional_patch(const char *first, const char *second, struct patch *patch)
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{
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int p_value = 1;
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char *name;
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first += 4; // skip "--- "
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second += 4; // skip "+++ "
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if (is_dev_null(first)) {
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patch->is_new = 1;
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patch->is_delete = 0;
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name = find_name(second, def_name, p_value, TERM_SPACE | TERM_TAB);
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patch->new_name = name;
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} else if (is_dev_null(second)) {
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patch->is_new = 0;
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patch->is_delete = 1;
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name = find_name(first, def_name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
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patch->old_name = name;
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} else {
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name = find_name(first, def_name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
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name = find_name(second, name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
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patch->old_name = patch->new_name = name;
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}
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if (!name)
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die("unable to find filename in patch at line %d", linenr);
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}
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static int gitdiff_hdrend(const char *line, struct patch *patch)
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{
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return -1;
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}
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/*
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* We're anal about diff header consistency, to make
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* sure that we don't end up having strange ambiguous
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* patches floating around.
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*
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* As a result, gitdiff_{old|new}name() will check
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* their names against any previous information, just
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* to make sure..
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*/
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static char *gitdiff_verify_name(const char *line, int isnull, char *orig_name, const char *oldnew)
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{
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int len;
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const char *name;
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if (!orig_name && !isnull)
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return find_name(line, NULL, 1, 0);
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name = "/dev/null";
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len = 9;
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if (orig_name) {
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name = orig_name;
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len = strlen(name);
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if (isnull)
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die("git-apply: bad git-diff - expected /dev/null, got %s on line %d", name, linenr);
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}
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if (*name == '/')
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goto absolute_path;
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for (;;) {
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char c = *line++;
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if (c == '\n')
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break;
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if (c != '/')
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continue;
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absolute_path:
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if (memcmp(line, name, len) || line[len] != '\n')
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break;
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return orig_name;
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}
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die("git-apply: bad git-diff - inconsistent %s filename on line %d", oldnew, linenr);
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return NULL;
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}
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static int gitdiff_oldname(const char *line, struct patch *patch)
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{
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patch->old_name = gitdiff_verify_name(line, patch->is_new, patch->old_name, "old");
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return 0;
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}
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static int gitdiff_newname(const char *line, struct patch *patch)
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{
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patch->new_name = gitdiff_verify_name(line, patch->is_delete, patch->new_name, "new");
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return 0;
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}
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static int gitdiff_oldmode(const char *line, struct patch *patch)
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{
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patch->old_mode = strtoul(line, NULL, 8);
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return 0;
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}
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static int gitdiff_newmode(const char *line, struct patch *patch)
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{
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patch->new_mode = strtoul(line, NULL, 8);
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return 0;
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}
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static int gitdiff_delete(const char *line, struct patch *patch)
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{
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patch->is_delete = 1;
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return gitdiff_oldmode(line, patch);
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}
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static int gitdiff_newfile(const char *line, struct patch *patch)
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{
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patch->is_new = 1;
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return gitdiff_newmode(line, patch);
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}
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static int gitdiff_copysrc(const char *line, struct patch *patch)
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{
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patch->is_copy = 1;
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patch->old_name = find_name(line, NULL, 0, 0);
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return 0;
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}
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static int gitdiff_copydst(const char *line, struct patch *patch)
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{
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patch->is_copy = 1;
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patch->new_name = find_name(line, NULL, 0, 0);
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return 0;
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}
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static int gitdiff_renamesrc(const char *line, struct patch *patch)
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{
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patch->is_rename = 1;
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patch->old_name = find_name(line, NULL, 0, 0);
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return 0;
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}
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static int gitdiff_renamedst(const char *line, struct patch *patch)
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{
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patch->is_rename = 1;
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patch->new_name = find_name(line, NULL, 0, 0);
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return 0;
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}
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static int gitdiff_similarity(const char *line, struct patch *patch)
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{
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return 0;
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}
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/*
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* This is normal for a diff that doesn't change anything: we'll fall through
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* into the next diff. Tell the parser to break out.
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*/
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static int gitdiff_unrecognized(const char *line, struct patch *patch)
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{
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return -1;
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}
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/* Verify that we recognize the lines following a git header */
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static int parse_git_header(char *line, int len, unsigned int size, struct patch *patch)
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{
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unsigned long offset;
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/* A git diff has explicit new/delete information, so we don't guess */
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patch->is_new = 0;
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patch->is_delete = 0;
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line += len;
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size -= len;
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linenr++;
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for (offset = len ; size > 0 ; offset += len, size -= len, line += len, linenr++) {
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static const struct opentry {
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const char *str;
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int (*fn)(const char *, struct patch *);
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} optable[] = {
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{ "@@ -", gitdiff_hdrend },
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{ "--- ", gitdiff_oldname },
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{ "+++ ", gitdiff_newname },
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{ "old mode ", gitdiff_oldmode },
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{ "new mode ", gitdiff_newmode },
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{ "deleted file mode ", gitdiff_delete },
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{ "new file mode ", gitdiff_newfile },
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{ "copy from ", gitdiff_copysrc },
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{ "copy to ", gitdiff_copydst },
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{ "rename from ", gitdiff_renamesrc },
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{ "rename to ", gitdiff_renamedst },
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{ "similarity index ", gitdiff_similarity },
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{ "", gitdiff_unrecognized },
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};
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int i;
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len = linelen(line, size);
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if (!len || line[len-1] != '\n')
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break;
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for (i = 0; i < sizeof(optable) / sizeof(optable[0]); i++) {
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const struct opentry *p = optable + i;
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int oplen = strlen(p->str);
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if (len < oplen || memcmp(p->str, line, oplen))
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continue;
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if (p->fn(line + oplen, patch) < 0)
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return offset;
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break;
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}
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}
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return offset;
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}
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static int parse_num(const char *line, int len, int offset, const char *expect, unsigned long *p)
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{
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char *ptr;
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int digits, ex;
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if (offset < 0 || offset >= len)
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return -1;
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line += offset;
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len -= offset;
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if (!isdigit(*line))
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return -1;
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*p = strtoul(line, &ptr, 10);
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digits = ptr - line;
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offset += digits;
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line += digits;
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len -= digits;
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ex = strlen(expect);
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if (ex > len)
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return -1;
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if (memcmp(line, expect, ex))
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return -1;
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return offset + ex;
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}
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/*
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* Parse a unified diff fragment header of the
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* form "@@ -a,b +c,d @@"
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*/
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static int parse_fragment_header(char *line, int len, struct fragment *fragment)
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{
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int offset;
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if (!len || line[len-1] != '\n')
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return -1;
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/* Figure out the number of lines in a fragment */
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offset = parse_num(line, len, 4, ",", &fragment->oldpos);
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offset = parse_num(line, len, offset, " +", &fragment->oldlines);
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offset = parse_num(line, len, offset, ",", &fragment->newpos);
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offset = parse_num(line, len, offset, " @@", &fragment->newlines);
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return offset;
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}
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static int find_header(char *line, unsigned long size, int *hdrsize, struct patch *patch)
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{
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unsigned long offset, len;
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patch->is_rename = patch->is_copy = 0;
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patch->is_new = patch->is_delete = -1;
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patch->old_mode = patch->new_mode = 0;
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patch->old_name = patch->new_name = NULL;
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for (offset = 0; size > 0; offset += len, size -= len, line += len, linenr++) {
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unsigned long nextlen;
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len = linelen(line, size);
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if (!len)
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break;
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/* Testing this early allows us to take a few shortcuts.. */
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if (len < 6)
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continue;
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/*
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* Make sure we don't find any unconnected patch fragmants.
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* That's a sign that we didn't find a header, and that a
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* patch has become corrupted/broken up.
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*/
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if (!memcmp("@@ -", line, 4)) {
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struct fragment dummy;
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if (parse_fragment_header(line, len, &dummy) < 0)
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continue;
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error("patch fragment without header at line %d: %.*s", linenr, len-1, line);
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}
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if (size < len + 6)
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break;
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/*
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* Git patch? It might not have a real patch, just a rename
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* or mode change, so we handle that specially
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*/
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if (!memcmp("diff --git ", line, 11)) {
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int git_hdr_len = parse_git_header(line, len, size, patch);
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if (git_hdr_len < 0)
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continue;
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*hdrsize = git_hdr_len;
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return offset;
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}
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/** --- followed by +++ ? */
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if (memcmp("--- ", line, 4) || memcmp("+++ ", line + len, 4))
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continue;
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/*
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* We only accept unified patches, so we want it to
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* at least have "@@ -a,b +c,d @@\n", which is 14 chars
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* minimum
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*/
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nextlen = linelen(line + len, size - len);
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if (size < nextlen + 14 || memcmp("@@ -", line + len + nextlen, 4))
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continue;
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/* Ok, we'll consider it a patch */
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parse_traditional_patch(line, line+len, patch);
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*hdrsize = len + nextlen;
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linenr += 2;
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return offset;
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}
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return -1;
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}
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/*
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* Parse a unified diff. Note that this really needs
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* to parse each fragment separately, since the only
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* way to know the difference between a "---" that is
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* part of a patch, and a "---" that starts the next
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* patch is to look at the line counts..
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*/
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static int parse_fragment(char *line, unsigned long size, struct patch *patch, struct fragment *fragment)
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{
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int len = linelen(line, size), offset;
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unsigned long pos[4], oldlines, newlines;
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offset = parse_fragment_header(line, len, fragment);
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if (offset < 0)
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return -1;
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oldlines = fragment->oldlines;
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newlines = fragment->newlines;
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if (patch->is_new < 0 && (pos[0] || oldlines))
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patch->is_new = 0;
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if (patch->is_delete < 0 && (pos[1] || newlines))
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patch->is_delete = 0;
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/* Parse the thing.. */
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line += len;
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size -= len;
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linenr++;
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for (offset = len; size > 0; offset += len, size -= len, line += len, linenr++) {
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if (!oldlines && !newlines)
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break;
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len = linelen(line, size);
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if (!len || line[len-1] != '\n')
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return -1;
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switch (*line) {
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default:
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return -1;
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case ' ':
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oldlines--;
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newlines--;
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break;
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case '-':
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oldlines--;
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break;
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case '+':
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newlines--;
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break;
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}
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}
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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 = xmalloc(sizeof(*fragment));
|
|
memset(fragment, 0, 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 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);
|
|
|
|
return offset + hdrsize + patchsize;
|
|
}
|
|
|
|
static void apply_patch_list(struct patch *patch)
|
|
{
|
|
if (!patch)
|
|
die("no patch found");
|
|
do {
|
|
const char *old_name = patch->old_name;
|
|
const char *new_name = patch->new_name;
|
|
struct fragment *frag;
|
|
|
|
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;
|
|
}
|
|
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);
|
|
}
|
|
|
|
printf("Applying patch to %s\n", new_name);
|
|
printf(" new=%d delete=%d copy=%d rename=%d\n",
|
|
patch->is_new, patch->is_delete, patch->is_copy, patch->is_rename);
|
|
if (patch->old_mode != patch->new_mode)
|
|
printf(" %o->%o\n", patch->old_mode, patch->new_mode);
|
|
frag = patch->fragments;
|
|
while (frag) {
|
|
printf("Fragment %lu,%lu -> %lu,%lu\n%.*s",
|
|
frag->oldpos, frag->oldlines,
|
|
frag->newpos, frag->newlines,
|
|
frag->size, frag->patch);
|
|
frag = frag->next;
|
|
}
|
|
|
|
} while ((patch = patch->next) != NULL);
|
|
}
|
|
|
|
static int apply_patch(int fd)
|
|
{
|
|
unsigned long offset, size;
|
|
char *buffer = read_patch_file(fd, &size);
|
|
struct patch *list = NULL, **listp = &list;
|
|
|
|
if (!buffer)
|
|
return -1;
|
|
offset = 0;
|
|
while (size > 0) {
|
|
struct patch *patch;
|
|
int nr;
|
|
|
|
patch = xmalloc(sizeof(*patch));
|
|
memset(patch, 0, sizeof(*patch));
|
|
nr = parse_chunk(buffer + offset, size, patch);
|
|
if (nr < 0)
|
|
break;
|
|
*listp = patch;
|
|
listp = &patch->next;
|
|
offset += nr;
|
|
size -= nr;
|
|
}
|
|
|
|
apply_patch_list(list);
|
|
|
|
free(buffer);
|
|
return 0;
|
|
}
|
|
|
|
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;
|
|
|
|
if (!strcmp(arg, "-")) {
|
|
apply_patch(0);
|
|
read_stdin = 0;
|
|
continue;
|
|
}
|
|
if (!strcmp(arg, "--no-merge")) {
|
|
merge_patch = 0;
|
|
continue;
|
|
}
|
|
fd = open(arg, O_RDONLY);
|
|
if (fd < 0)
|
|
usage(apply_usage);
|
|
read_stdin = 0;
|
|
apply_patch(fd);
|
|
close(fd);
|
|
}
|
|
if (read_stdin)
|
|
apply_patch(0);
|
|
return 0;
|
|
}
|