1 | /* |
2 | * "Optimize" a list of dependencies as spit out by gcc -MD |
3 | * for the kernel build |
4 | * =========================================================================== |
5 | * |
6 | * Author Kai Germaschewski |
7 | * Copyright 2002 by Kai Germaschewski <kai.germaschewski@gmx.de> |
8 | * |
9 | * This software may be used and distributed according to the terms |
10 | * of the GNU General Public License, incorporated herein by reference. |
11 | * |
12 | * |
13 | * Introduction: |
14 | * |
15 | * gcc produces a very nice and correct list of dependencies which |
16 | * tells make when to remake a file. |
17 | * |
18 | * To use this list as-is however has the drawback that virtually |
19 | * every file in the kernel includes autoconf.h. |
20 | * |
21 | * If the user re-runs make *config, autoconf.h will be |
22 | * regenerated. make notices that and will rebuild every file which |
23 | * includes autoconf.h, i.e. basically all files. This is extremely |
24 | * annoying if the user just changed CONFIG_HIS_DRIVER from n to m. |
25 | * |
26 | * So we play the same trick that "mkdep" played before. We replace |
27 | * the dependency on autoconf.h by a dependency on every config |
28 | * option which is mentioned in any of the listed prerequisites. |
29 | * |
30 | * kconfig populates a tree in include/config/ with an empty file |
31 | * for each config symbol and when the configuration is updated |
32 | * the files representing changed config options are touched |
33 | * which then let make pick up the changes and the files that use |
34 | * the config symbols are rebuilt. |
35 | * |
36 | * So if the user changes his CONFIG_HIS_DRIVER option, only the objects |
37 | * which depend on "include/config/HIS_DRIVER" will be rebuilt, |
38 | * so most likely only his driver ;-) |
39 | * |
40 | * The idea above dates, by the way, back to Michael E Chastain, AFAIK. |
41 | * |
42 | * So to get dependencies right, there are two issues: |
43 | * o if any of the files the compiler read changed, we need to rebuild |
44 | * o if the command line given to the compile the file changed, we |
45 | * better rebuild as well. |
46 | * |
47 | * The former is handled by using the -MD output, the later by saving |
48 | * the command line used to compile the old object and comparing it |
49 | * to the one we would now use. |
50 | * |
51 | * Again, also this idea is pretty old and has been discussed on |
52 | * kbuild-devel a long time ago. I don't have a sensibly working |
53 | * internet connection right now, so I rather don't mention names |
54 | * without double checking. |
55 | * |
56 | * This code here has been based partially based on mkdep.c, which |
57 | * says the following about its history: |
58 | * |
59 | * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>. |
60 | * This is a C version of syncdep.pl by Werner Almesberger. |
61 | * |
62 | * |
63 | * It is invoked as |
64 | * |
65 | * fixdep <depfile> <target> <cmdline> |
66 | * |
67 | * and will read the dependency file <depfile> |
68 | * |
69 | * The transformed dependency snipped is written to stdout. |
70 | * |
71 | * It first generates a line |
72 | * |
73 | * savedcmd_<target> = <cmdline> |
74 | * |
75 | * and then basically copies the .<target>.d file to stdout, in the |
76 | * process filtering out the dependency on autoconf.h and adding |
77 | * dependencies on include/config/MY_OPTION for every |
78 | * CONFIG_MY_OPTION encountered in any of the prerequisites. |
79 | * |
80 | * We don't even try to really parse the header files, but |
81 | * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will |
82 | * be picked up as well. It's not a problem with respect to |
83 | * correctness, since that can only give too many dependencies, thus |
84 | * we cannot miss a rebuild. Since people tend to not mention totally |
85 | * unrelated CONFIG_ options all over the place, it's not an |
86 | * efficiency problem either. |
87 | * |
88 | * (Note: it'd be easy to port over the complete mkdep state machine, |
89 | * but I don't think the added complexity is worth it) |
90 | */ |
91 | |
92 | #include <sys/types.h> |
93 | #include <sys/stat.h> |
94 | #include <unistd.h> |
95 | #include <fcntl.h> |
96 | #include <string.h> |
97 | #include <stdbool.h> |
98 | #include <stdlib.h> |
99 | #include <stdio.h> |
100 | #include <ctype.h> |
101 | |
102 | static void usage(void) |
103 | { |
104 | fprintf(stderr, format: "Usage: fixdep <depfile> <target> <cmdline>\n" ); |
105 | exit(status: 1); |
106 | } |
107 | |
108 | struct item { |
109 | struct item *next; |
110 | unsigned int len; |
111 | unsigned int hash; |
112 | char name[]; |
113 | }; |
114 | |
115 | #define HASHSZ 256 |
116 | static struct item *config_hashtab[HASHSZ], *file_hashtab[HASHSZ]; |
117 | |
118 | static unsigned int strhash(const char *str, unsigned int sz) |
119 | { |
120 | /* fnv32 hash */ |
121 | unsigned int i, hash = 2166136261U; |
122 | |
123 | for (i = 0; i < sz; i++) |
124 | hash = (hash ^ str[i]) * 0x01000193; |
125 | return hash; |
126 | } |
127 | |
128 | /* |
129 | * Add a new value to the configuration string. |
130 | */ |
131 | static void add_to_hashtable(const char *name, int len, unsigned int hash, |
132 | struct item *hashtab[]) |
133 | { |
134 | struct item *aux = malloc(size: sizeof(*aux) + len); |
135 | |
136 | if (!aux) { |
137 | perror(s: "fixdep:malloc" ); |
138 | exit(status: 1); |
139 | } |
140 | memcpy(dest: aux->name, src: name, n: len); |
141 | aux->len = len; |
142 | aux->hash = hash; |
143 | aux->next = hashtab[hash % HASHSZ]; |
144 | hashtab[hash % HASHSZ] = aux; |
145 | } |
146 | |
147 | /* |
148 | * Lookup a string in the hash table. If found, just return true. |
149 | * If not, add it to the hashtable and return false. |
150 | */ |
151 | static bool in_hashtable(const char *name, int len, struct item *hashtab[]) |
152 | { |
153 | struct item *aux; |
154 | unsigned int hash = strhash(str: name, sz: len); |
155 | |
156 | for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) { |
157 | if (aux->hash == hash && aux->len == len && |
158 | memcmp(s1: aux->name, s2: name, n: len) == 0) |
159 | return true; |
160 | } |
161 | |
162 | add_to_hashtable(name, len, hash, hashtab); |
163 | |
164 | return false; |
165 | } |
166 | |
167 | /* |
168 | * Record the use of a CONFIG_* word. |
169 | */ |
170 | static void use_config(const char *m, int slen) |
171 | { |
172 | if (in_hashtable(name: m, len: slen, hashtab: config_hashtab)) |
173 | return; |
174 | |
175 | /* Print out a dependency path from a symbol name. */ |
176 | printf(format: " $(wildcard include/config/%.*s) \\\n" , slen, m); |
177 | } |
178 | |
179 | /* test if s ends in sub */ |
180 | static int str_ends_with(const char *s, int slen, const char *sub) |
181 | { |
182 | int sublen = strlen(s: sub); |
183 | |
184 | if (sublen > slen) |
185 | return 0; |
186 | |
187 | return !memcmp(s1: s + slen - sublen, s2: sub, n: sublen); |
188 | } |
189 | |
190 | static void parse_config_file(const char *p) |
191 | { |
192 | const char *q, *r; |
193 | const char *start = p; |
194 | |
195 | while ((p = strstr(haystack: p, needle: "CONFIG_" ))) { |
196 | if (p > start && (isalnum(p[-1]) || p[-1] == '_')) { |
197 | p += 7; |
198 | continue; |
199 | } |
200 | p += 7; |
201 | q = p; |
202 | while (isalnum(*q) || *q == '_') |
203 | q++; |
204 | if (str_ends_with(s: p, slen: q - p, sub: "_MODULE" )) |
205 | r = q - 7; |
206 | else |
207 | r = q; |
208 | if (r > p) |
209 | use_config(m: p, slen: r - p); |
210 | p = q; |
211 | } |
212 | } |
213 | |
214 | static void *read_file(const char *filename) |
215 | { |
216 | struct stat st; |
217 | int fd; |
218 | char *buf; |
219 | |
220 | fd = open(file: filename, O_RDONLY); |
221 | if (fd < 0) { |
222 | fprintf(stderr, format: "fixdep: error opening file: " ); |
223 | perror(s: filename); |
224 | exit(status: 2); |
225 | } |
226 | if (fstat(fd: fd, buf: &st) < 0) { |
227 | fprintf(stderr, format: "fixdep: error fstat'ing file: " ); |
228 | perror(s: filename); |
229 | exit(status: 2); |
230 | } |
231 | buf = malloc(size: st.st_size + 1); |
232 | if (!buf) { |
233 | perror(s: "fixdep: malloc" ); |
234 | exit(status: 2); |
235 | } |
236 | if (read(fd: fd, buf: buf, nbytes: st.st_size) != st.st_size) { |
237 | perror(s: "fixdep: read" ); |
238 | exit(status: 2); |
239 | } |
240 | buf[st.st_size] = '\0'; |
241 | close(fd: fd); |
242 | |
243 | return buf; |
244 | } |
245 | |
246 | /* Ignore certain dependencies */ |
247 | static int is_ignored_file(const char *s, int len) |
248 | { |
249 | return str_ends_with(s, slen: len, sub: "include/generated/autoconf.h" ); |
250 | } |
251 | |
252 | /* Do not parse these files */ |
253 | static int is_no_parse_file(const char *s, int len) |
254 | { |
255 | /* rustc may list binary files in dep-info */ |
256 | return str_ends_with(s, slen: len, sub: ".rlib" ) || |
257 | str_ends_with(s, slen: len, sub: ".rmeta" ) || |
258 | str_ends_with(s, slen: len, sub: ".so" ); |
259 | } |
260 | |
261 | /* |
262 | * Important: The below generated source_foo.o and deps_foo.o variable |
263 | * assignments are parsed not only by make, but also by the rather simple |
264 | * parser in scripts/mod/sumversion.c. |
265 | */ |
266 | static void parse_dep_file(char *p, const char *target) |
267 | { |
268 | bool saw_any_target = false; |
269 | bool is_target = true; |
270 | bool is_source = false; |
271 | bool need_parse; |
272 | char *q, saved_c; |
273 | |
274 | while (*p) { |
275 | /* handle some special characters first. */ |
276 | switch (*p) { |
277 | case '#': |
278 | /* |
279 | * skip comments. |
280 | * rustc may emit comments to dep-info. |
281 | */ |
282 | p++; |
283 | while (*p != '\0' && *p != '\n') { |
284 | /* |
285 | * escaped newlines continue the comment across |
286 | * multiple lines. |
287 | */ |
288 | if (*p == '\\') |
289 | p++; |
290 | p++; |
291 | } |
292 | continue; |
293 | case ' ': |
294 | case '\t': |
295 | /* skip whitespaces */ |
296 | p++; |
297 | continue; |
298 | case '\\': |
299 | /* |
300 | * backslash/newline combinations continue the |
301 | * statement. Skip it just like a whitespace. |
302 | */ |
303 | if (*(p + 1) == '\n') { |
304 | p += 2; |
305 | continue; |
306 | } |
307 | break; |
308 | case '\n': |
309 | /* |
310 | * Makefiles use a line-based syntax, where the newline |
311 | * is the end of a statement. After seeing a newline, |
312 | * we expect the next token is a target. |
313 | */ |
314 | p++; |
315 | is_target = true; |
316 | continue; |
317 | case ':': |
318 | /* |
319 | * assume the first dependency after a colon as the |
320 | * source file. |
321 | */ |
322 | p++; |
323 | is_target = false; |
324 | is_source = true; |
325 | continue; |
326 | } |
327 | |
328 | /* find the end of the token */ |
329 | q = p; |
330 | while (*q != ' ' && *q != '\t' && *q != '\n' && *q != '#' && *q != ':') { |
331 | if (*q == '\\') { |
332 | /* |
333 | * backslash/newline combinations work like as |
334 | * a whitespace, so this is the end of token. |
335 | */ |
336 | if (*(q + 1) == '\n') |
337 | break; |
338 | |
339 | /* escaped special characters */ |
340 | if (*(q + 1) == '#' || *(q + 1) == ':') { |
341 | memmove(dest: p + 1, src: p, n: q - p); |
342 | p++; |
343 | } |
344 | |
345 | q++; |
346 | } |
347 | |
348 | if (*q == '\0') |
349 | break; |
350 | q++; |
351 | } |
352 | |
353 | /* Just discard the target */ |
354 | if (is_target) { |
355 | p = q; |
356 | continue; |
357 | } |
358 | |
359 | saved_c = *q; |
360 | *q = '\0'; |
361 | need_parse = false; |
362 | |
363 | /* |
364 | * Do not list the source file as dependency, so that kbuild is |
365 | * not confused if a .c file is rewritten into .S or vice versa. |
366 | * Storing it in source_* is needed for modpost to compute |
367 | * srcversions. |
368 | */ |
369 | if (is_source) { |
370 | /* |
371 | * The DT build rule concatenates multiple dep files. |
372 | * When processing them, only process the first source |
373 | * name, which will be the original one, and ignore any |
374 | * other source names, which will be intermediate |
375 | * temporary files. |
376 | * |
377 | * rustc emits the same dependency list for each |
378 | * emission type. It is enough to list the source name |
379 | * just once. |
380 | */ |
381 | if (!saw_any_target) { |
382 | saw_any_target = true; |
383 | printf(format: "source_%s := %s\n\n" , target, p); |
384 | printf(format: "deps_%s := \\\n" , target); |
385 | need_parse = true; |
386 | } |
387 | } else if (!is_ignored_file(s: p, len: q - p) && |
388 | !in_hashtable(name: p, len: q - p, hashtab: file_hashtab)) { |
389 | printf(format: " %s \\\n" , p); |
390 | need_parse = true; |
391 | } |
392 | |
393 | if (need_parse && !is_no_parse_file(s: p, len: q - p)) { |
394 | void *buf; |
395 | |
396 | buf = read_file(filename: p); |
397 | parse_config_file(p: buf); |
398 | free(ptr: buf); |
399 | } |
400 | |
401 | is_source = false; |
402 | *q = saved_c; |
403 | p = q; |
404 | } |
405 | |
406 | if (!saw_any_target) { |
407 | fprintf(stderr, format: "fixdep: parse error; no targets found\n" ); |
408 | exit(status: 1); |
409 | } |
410 | |
411 | printf(format: "\n%s: $(deps_%s)\n\n" , target, target); |
412 | printf(format: "$(deps_%s):\n" , target); |
413 | } |
414 | |
415 | int main(int argc, char *argv[]) |
416 | { |
417 | const char *depfile, *target, *cmdline; |
418 | void *buf; |
419 | |
420 | if (argc != 4) |
421 | usage(); |
422 | |
423 | depfile = argv[1]; |
424 | target = argv[2]; |
425 | cmdline = argv[3]; |
426 | |
427 | printf(format: "savedcmd_%s := %s\n\n" , target, cmdline); |
428 | |
429 | buf = read_file(filename: depfile); |
430 | parse_dep_file(p: buf, target); |
431 | free(ptr: buf); |
432 | |
433 | fflush(stdout); |
434 | |
435 | /* |
436 | * In the intended usage, the stdout is redirected to .*.cmd files. |
437 | * Call ferror() to catch errors such as "No space left on device". |
438 | */ |
439 | if (ferror(stdout)) { |
440 | fprintf(stderr, format: "fixdep: not all data was written to the output\n" ); |
441 | exit(status: 1); |
442 | } |
443 | |
444 | return 0; |
445 | } |
446 | |