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c1bb9350 LT |
1 | /* |
2 | * apply.c | |
3 | * | |
4 | * Copyright (C) Linus Torvalds, 2005 | |
5 | * | |
6 | * This applies patches on top of some (arbitrary) version of the SCM. | |
7 | * | |
8 | * NOTE! It does all its work in the index file, and only cares about | |
9 | * the files in the working directory if you tell it to "merge" the | |
10 | * patch apply. | |
11 | * | |
12 | * Even when merging it always takes the source from the index, and | |
13 | * uses the working tree as a "branch" for a 3-way merge. | |
14 | */ | |
15 | #include <ctype.h> | |
16 | ||
17 | #include "cache.h" | |
18 | ||
19 | // We default to the merge behaviour, since that's what most people would | |
20 | // expect | |
21 | static int merge_patch = 1; | |
22 | static const char apply_usage[] = "git-apply <patch>"; | |
23 | ||
24 | #define CHUNKSIZE (8192) | |
25 | ||
26 | static void *read_patch_file(int fd, unsigned long *sizep) | |
27 | { | |
28 | unsigned long size = 0, alloc = CHUNKSIZE; | |
29 | void *buffer = xmalloc(alloc); | |
30 | ||
31 | for (;;) { | |
32 | int nr = alloc - size; | |
33 | if (nr < 1024) { | |
34 | alloc += CHUNKSIZE; | |
35 | buffer = xrealloc(buffer, alloc); | |
36 | nr = alloc - size; | |
37 | } | |
38 | nr = read(fd, buffer + size, nr); | |
39 | if (!nr) | |
40 | break; | |
41 | if (nr < 0) { | |
42 | if (errno == EAGAIN) | |
43 | continue; | |
44 | die("git-apply: read returned %s", strerror(errno)); | |
45 | } | |
46 | size += nr; | |
47 | } | |
48 | *sizep = size; | |
49 | return buffer; | |
50 | } | |
51 | ||
52 | static unsigned long linelen(char *buffer, unsigned long size) | |
53 | { | |
54 | unsigned long len = 0; | |
55 | while (size--) { | |
56 | len++; | |
57 | if (*buffer++ == '\n') | |
58 | break; | |
59 | } | |
60 | return len; | |
61 | } | |
62 | ||
63 | static int match_word(const char *line, const char *match) | |
64 | { | |
65 | for (;;) { | |
66 | char c = *match++; | |
67 | if (!c) | |
68 | break; | |
69 | if (*line++ != c) | |
70 | return 0; | |
71 | } | |
72 | return *line == ' '; | |
73 | } | |
74 | ||
75 | /* Verify that we recognize the lines following a git header */ | |
76 | static int parse_git_header(char *line, unsigned int size) | |
77 | { | |
78 | unsigned long offset, len; | |
79 | ||
80 | for (offset = 0 ; size > 0 ; offset += len, size -= len, line += len) { | |
81 | len = linelen(line, size); | |
82 | if (!len) | |
83 | break; | |
84 | if (line[len-1] != '\n') | |
85 | return -1; | |
86 | if (len < 4) | |
87 | break; | |
88 | if (!memcmp(line, "@@ -", 4)) | |
89 | return offset; | |
90 | if (match_word(line, "new file mode")) | |
91 | continue; | |
92 | if (match_word(line, "deleted file mode")) | |
93 | continue; | |
94 | if (match_word(line, "copy")) | |
95 | continue; | |
96 | if (match_word(line, "rename")) | |
97 | continue; | |
98 | if (match_word(line, "similarity index")) | |
99 | continue; | |
100 | break; | |
101 | } | |
102 | ||
103 | /* We want either a patch _or_ something real */ | |
104 | return offset ? :-1; | |
105 | } | |
106 | ||
107 | static int find_header(char *line, unsigned long size, int *hdrsize) | |
108 | { | |
109 | unsigned long offset, len; | |
110 | ||
111 | for (offset = 0; size > 0; offset += len, size -= len, line += len) { | |
112 | unsigned long nextlen; | |
113 | ||
114 | len = linelen(line, size); | |
115 | if (!len) | |
116 | break; | |
117 | ||
118 | /* Testing this early allows us to take a few shortcuts.. */ | |
119 | if (len < 6) | |
120 | continue; | |
121 | if (size < len + 6) | |
122 | break; | |
123 | ||
124 | /* | |
125 | * Git patch? It might not have a real patch, just a rename | |
126 | * or mode change, so we handle that specially | |
127 | */ | |
128 | if (!memcmp("diff --git ", line, 11)) { | |
129 | int git_hdr_len = parse_git_header(line + len, size - len); | |
130 | if (git_hdr_len < 0) | |
131 | continue; | |
132 | ||
133 | *hdrsize = len + git_hdr_len; | |
134 | return offset; | |
135 | } | |
136 | ||
137 | /** --- followed by +++ ? */ | |
138 | if (memcmp("--- ", line, 4) || memcmp("+++ ", line + len, 4)) | |
139 | continue; | |
140 | ||
141 | /* | |
142 | * We only accept unified patches, so we want it to | |
143 | * at least have "@@ -a,b +c,d @@\n", which is 14 chars | |
144 | * minimum | |
145 | */ | |
146 | nextlen = linelen(line + len, size - len); | |
147 | if (size < nextlen + 14 || memcmp("@@ -", line + len + nextlen, 4)) | |
148 | continue; | |
149 | ||
150 | /* Ok, we'll consider it a patch */ | |
151 | *hdrsize = len + nextlen; | |
152 | return offset; | |
153 | } | |
154 | return -1; | |
155 | } | |
156 | ||
157 | static int parse_num(const char *line, int len, int offset, const char *expect, unsigned long *p) | |
158 | { | |
159 | char *ptr; | |
160 | int digits, ex; | |
161 | ||
162 | if (offset < 0 || offset >= len) | |
163 | return -1; | |
164 | line += offset; | |
165 | len -= offset; | |
166 | ||
167 | if (!isdigit(*line)) | |
168 | return -1; | |
169 | *p = strtoul(line, &ptr, 10); | |
170 | ||
171 | digits = ptr - line; | |
172 | ||
173 | offset += digits; | |
174 | line += digits; | |
175 | len -= digits; | |
176 | ||
177 | ex = strlen(expect); | |
178 | if (ex > len) | |
179 | return -1; | |
180 | if (memcmp(line, expect, ex)) | |
181 | return -1; | |
182 | ||
183 | return offset + ex; | |
184 | } | |
185 | ||
186 | /* | |
187 | * Parse a unified diff. Note that this really needs | |
188 | * to parse each fragment separately, since the only | |
189 | * way to know the difference between a "---" that is | |
190 | * part of a patch, and a "---" that starts the next | |
191 | * patch is to look at the line counts.. | |
192 | */ | |
193 | static int apply_fragment(char *line, unsigned long size) | |
194 | { | |
195 | int len = linelen(line, size), offset; | |
196 | unsigned long oldpos, oldlines, newpos, newlines; | |
197 | ||
198 | if (!len || line[len-1] != '\n') | |
199 | return -1; | |
200 | ||
201 | /* Figure out the number of lines in a fragment */ | |
202 | offset = parse_num(line, len, 4, ",", &oldpos); | |
203 | offset = parse_num(line, len, offset, " +", &oldlines); | |
204 | offset = parse_num(line, len, offset, ",", &newpos); | |
205 | offset = parse_num(line, len, offset, " @@", &newlines); | |
206 | if (offset < 0) | |
207 | return -1; | |
208 | ||
209 | /* Parse the thing.. */ | |
210 | line += len; | |
211 | size -= len; | |
212 | for (offset = len; size > 0; offset += len, size -= len, line += len) { | |
213 | if (!oldlines && !newlines) | |
214 | break; | |
215 | len = linelen(line, size); | |
216 | if (!len || line[len-1] != '\n') | |
217 | return -1; | |
218 | switch (*line) { | |
219 | default: | |
220 | return -1; | |
221 | case ' ': | |
222 | oldlines--; | |
223 | newlines--; | |
224 | break; | |
225 | case '-': | |
226 | oldlines--; | |
227 | break; | |
228 | case '+': | |
229 | newlines--; | |
230 | break; | |
231 | } | |
232 | } | |
233 | return offset; | |
234 | } | |
235 | ||
236 | static int apply_single_patch(char *line, unsigned long size) | |
237 | { | |
238 | unsigned long offset = 0; | |
239 | ||
240 | while (size > 4 && !memcmp(line, "@@ -", 4)) { | |
241 | int len = apply_fragment(line, size); | |
242 | if (len <= 0) | |
5e224a2e | 243 | die("corrupt patch"); |
c1bb9350 LT |
244 | |
245 | printf("applying fragment:\n%.*s\n\n", len, line); | |
246 | ||
247 | offset += len; | |
248 | line += len; | |
249 | size -= len; | |
250 | } | |
251 | return offset; | |
252 | } | |
253 | ||
254 | static int apply_chunk(char *buffer, unsigned long size) | |
255 | { | |
256 | int hdrsize, patchsize; | |
257 | int offset = find_header(buffer, size, &hdrsize); | |
258 | char *header, *patch; | |
259 | ||
260 | if (offset < 0) | |
261 | return offset; | |
262 | header = buffer + offset; | |
263 | ||
264 | printf("Found header:\n%.*s\n\n", hdrsize, header); | |
265 | ||
266 | patch = header + hdrsize; | |
267 | patchsize = apply_single_patch(patch, size - offset - hdrsize); | |
268 | ||
269 | return offset + hdrsize + patchsize; | |
270 | } | |
271 | ||
272 | static int apply_patch(int fd) | |
273 | { | |
274 | unsigned long offset, size; | |
275 | char *buffer = read_patch_file(fd, &size); | |
276 | ||
277 | if (!buffer) | |
278 | return -1; | |
279 | offset = 0; | |
280 | while (size > 0) { | |
281 | int nr = apply_chunk(buffer + offset, size); | |
282 | if (nr < 0) | |
283 | break; | |
284 | offset += nr; | |
285 | size -= nr; | |
286 | } | |
287 | free(buffer); | |
288 | return 0; | |
289 | } | |
290 | ||
291 | int main(int argc, char **argv) | |
292 | { | |
293 | int i; | |
294 | ||
295 | if (read_cache() < 0) | |
296 | die("unable to read index file"); | |
297 | ||
298 | for (i = 1; i < argc; i++) { | |
299 | const char *arg = argv[i]; | |
300 | int fd; | |
301 | ||
302 | if (!strcmp(arg, "-")) { | |
303 | apply_patch(0); | |
304 | continue; | |
305 | } | |
306 | if (!strcmp(arg, "--no-merge")) { | |
307 | merge_patch = 0; | |
308 | continue; | |
309 | } | |
310 | fd = open(arg, O_RDONLY); | |
311 | if (fd < 0) | |
312 | usage(apply_usage); | |
313 | apply_patch(fd); | |
314 | close(fd); | |
315 | } | |
316 | return 0; | |
317 | } |