fixdep.c 11 KB

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  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 prequisites.
  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/linux/config/his/driver.h" 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. * cmd_<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.h for every
  78. * CONFIG_MY_OPTION encountered in any of the prequisites.
  79. *
  80. * It will also filter out all the dependencies on *.ver. We need
  81. * to make sure that the generated version checksum are globally up
  82. * to date before even starting the recursive build, so it's too late
  83. * at this point anyway.
  84. *
  85. * The algorithm to grep for "CONFIG_..." is bit unusual, but should
  86. * be fast ;-) We don't even try to really parse the header files, but
  87. * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will
  88. * be picked up as well. It's not a problem with respect to
  89. * correctness, since that can only give too many dependencies, thus
  90. * we cannot miss a rebuild. Since people tend to not mention totally
  91. * unrelated CONFIG_ options all over the place, it's not an
  92. * efficiency problem either.
  93. *
  94. * (Note: it'd be easy to port over the complete mkdep state machine,
  95. * but I don't think the added complexity is worth it)
  96. */
  97. /*
  98. * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto
  99. * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not
  100. * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as
  101. * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h,
  102. * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that
  103. * those files will have correct dependencies.
  104. */
  105. #include <sys/types.h>
  106. #include <sys/stat.h>
  107. #include <sys/mman.h>
  108. #include <unistd.h>
  109. #include <fcntl.h>
  110. #include <string.h>
  111. #include <stdlib.h>
  112. #include <stdio.h>
  113. #include <limits.h>
  114. #include <ctype.h>
  115. #include <arpa/inet.h>
  116. #define INT_CONF ntohl(0x434f4e46)
  117. #define INT_ONFI ntohl(0x4f4e4649)
  118. #define INT_NFIG ntohl(0x4e464947)
  119. #define INT_FIG_ ntohl(0x4649475f)
  120. char *target;
  121. char *depfile;
  122. char *cmdline;
  123. static void usage(void)
  124. {
  125. fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
  126. exit(1);
  127. }
  128. /*
  129. * Print out the commandline prefixed with cmd_<target filename> :=
  130. */
  131. static void print_cmdline(void)
  132. {
  133. printf("cmd_%s := %s\n\n", target, cmdline);
  134. }
  135. struct item {
  136. struct item *next;
  137. unsigned int len;
  138. unsigned int hash;
  139. char name[0];
  140. };
  141. #define HASHSZ 256
  142. static struct item *hashtab[HASHSZ];
  143. static unsigned int strhash(const char *str, unsigned int sz)
  144. {
  145. /* fnv32 hash */
  146. unsigned int i, hash = 2166136261U;
  147. for (i = 0; i < sz; i++)
  148. hash = (hash ^ str[i]) * 0x01000193;
  149. return hash;
  150. }
  151. /*
  152. * Lookup a value in the configuration string.
  153. */
  154. static int is_defined_config(const char *name, int len, unsigned int hash)
  155. {
  156. struct item *aux;
  157. for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {
  158. if (aux->hash == hash && aux->len == len &&
  159. memcmp(aux->name, name, len) == 0)
  160. return 1;
  161. }
  162. return 0;
  163. }
  164. /*
  165. * Add a new value to the configuration string.
  166. */
  167. static void define_config(const char *name, int len, unsigned int hash)
  168. {
  169. struct item *aux = malloc(sizeof(*aux) + len);
  170. if (!aux) {
  171. perror("fixdep:malloc");
  172. exit(1);
  173. }
  174. memcpy(aux->name, name, len);
  175. aux->len = len;
  176. aux->hash = hash;
  177. aux->next = hashtab[hash % HASHSZ];
  178. hashtab[hash % HASHSZ] = aux;
  179. }
  180. /*
  181. * Clear the set of configuration strings.
  182. */
  183. static void clear_config(void)
  184. {
  185. struct item *aux, *next;
  186. unsigned int i;
  187. for (i = 0; i < HASHSZ; i++) {
  188. for (aux = hashtab[i]; aux; aux = next) {
  189. next = aux->next;
  190. free(aux);
  191. }
  192. hashtab[i] = NULL;
  193. }
  194. }
  195. /*
  196. * Record the use of a CONFIG_* word.
  197. */
  198. static void use_config(const char *m, int slen)
  199. {
  200. unsigned int hash = strhash(m, slen);
  201. int c, i;
  202. if (is_defined_config(m, slen, hash))
  203. return;
  204. define_config(m, slen, hash);
  205. printf(" $(wildcard include/config/");
  206. for (i = 0; i < slen; i++) {
  207. c = m[i];
  208. if (c == '_')
  209. c = '/';
  210. else
  211. c = tolower(c);
  212. putchar(c);
  213. }
  214. printf(".h) \\\n");
  215. }
  216. static void parse_config_file(const char *map, size_t len)
  217. {
  218. const int *end = (const int *) (map + len);
  219. /* start at +1, so that p can never be < map */
  220. const int *m = (const int *) map + 1;
  221. const char *p, *q;
  222. for (; m < end; m++) {
  223. if (*m == INT_CONF) { p = (char *) m ; goto conf; }
  224. if (*m == INT_ONFI) { p = (char *) m-1; goto conf; }
  225. if (*m == INT_NFIG) { p = (char *) m-2; goto conf; }
  226. if (*m == INT_FIG_) { p = (char *) m-3; goto conf; }
  227. continue;
  228. conf:
  229. if (p > map + len - 7)
  230. continue;
  231. if (memcmp(p, "CONFIG_", 7))
  232. continue;
  233. for (q = p + 7; q < map + len; q++) {
  234. if (!(isalnum(*q) || *q == '_'))
  235. goto found;
  236. }
  237. continue;
  238. found:
  239. if (!memcmp(q - 7, "_MODULE", 7))
  240. q -= 7;
  241. if( (q-p-7) < 0 )
  242. continue;
  243. use_config(p+7, q-p-7);
  244. }
  245. }
  246. /* test is s ends in sub */
  247. static int strrcmp(char *s, char *sub)
  248. {
  249. int slen = strlen(s);
  250. int sublen = strlen(sub);
  251. if (sublen > slen)
  252. return 1;
  253. return memcmp(s + slen - sublen, sub, sublen);
  254. }
  255. static void do_config_file(const char *filename)
  256. {
  257. struct stat st;
  258. int fd;
  259. void *map;
  260. fd = open(filename, O_RDONLY);
  261. if (fd < 0) {
  262. fprintf(stderr, "fixdep: error opening config file: ");
  263. perror(filename);
  264. exit(2);
  265. }
  266. fstat(fd, &st);
  267. if (st.st_size == 0) {
  268. close(fd);
  269. return;
  270. }
  271. map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
  272. if ((long) map == -1) {
  273. perror("fixdep: mmap");
  274. close(fd);
  275. return;
  276. }
  277. parse_config_file(map, st.st_size);
  278. munmap(map, st.st_size);
  279. close(fd);
  280. }
  281. /*
  282. * Important: The below generated source_foo.o and deps_foo.o variable
  283. * assignments are parsed not only by make, but also by the rather simple
  284. * parser in scripts/mod/sumversion.c.
  285. */
  286. static void parse_dep_file(void *map, size_t len)
  287. {
  288. char *m = map;
  289. char *end = m + len;
  290. char *p;
  291. char s[PATH_MAX];
  292. int is_target;
  293. int saw_any_target = 0;
  294. int is_first_dep = 0;
  295. clear_config();
  296. while (m < end) {
  297. /* Skip any "white space" */
  298. while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
  299. m++;
  300. /* Find next "white space" */
  301. p = m;
  302. while (p < end && *p != ' ' && *p != '\\' && *p != '\n')
  303. p++;
  304. /* Is the token we found a target name? */
  305. is_target = (*(p-1) == ':');
  306. /* Don't write any target names into the dependency file */
  307. if (is_target) {
  308. /* The /next/ file is the first dependency */
  309. is_first_dep = 1;
  310. } else {
  311. /* Save this token/filename */
  312. memcpy(s, m, p-m);
  313. s[p - m] = 0;
  314. /* Ignore certain dependencies */
  315. if (strrcmp(s, "include/generated/autoconf.h") &&
  316. strrcmp(s, "arch/um/include/uml-config.h") &&
  317. strrcmp(s, "include/linux/kconfig.h") &&
  318. strrcmp(s, ".ver")) {
  319. /*
  320. * Do not list the source file as dependency,
  321. * so that kbuild is not confused if a .c file
  322. * is rewritten into .S or vice versa. Storing
  323. * it in source_* is needed for modpost to
  324. * compute srcversions.
  325. */
  326. if (is_first_dep) {
  327. /*
  328. * If processing the concatenation of
  329. * multiple dependency files, only
  330. * process the first target name, which
  331. * will be the original source name,
  332. * and ignore any other target names,
  333. * which will be intermediate temporary
  334. * files.
  335. */
  336. if (!saw_any_target) {
  337. saw_any_target = 1;
  338. printf("source_%s := %s\n\n",
  339. target, s);
  340. printf("deps_%s := \\\n",
  341. target);
  342. }
  343. is_first_dep = 0;
  344. } else
  345. printf(" %s \\\n", s);
  346. do_config_file(s);
  347. }
  348. }
  349. /*
  350. * Start searching for next token immediately after the first
  351. * "whitespace" character that follows this token.
  352. */
  353. m = p + 1;
  354. }
  355. if (!saw_any_target) {
  356. fprintf(stderr, "fixdep: parse error; no targets found\n");
  357. exit(1);
  358. }
  359. printf("\n%s: $(deps_%s)\n\n", target, target);
  360. printf("$(deps_%s):\n", target);
  361. }
  362. static void print_deps(void)
  363. {
  364. struct stat st;
  365. int fd;
  366. void *map;
  367. fd = open(depfile, O_RDONLY);
  368. if (fd < 0) {
  369. fprintf(stderr, "fixdep: error opening depfile: ");
  370. perror(depfile);
  371. exit(2);
  372. }
  373. if (fstat(fd, &st) < 0) {
  374. fprintf(stderr, "fixdep: error fstat'ing depfile: ");
  375. perror(depfile);
  376. exit(2);
  377. }
  378. if (st.st_size == 0) {
  379. fprintf(stderr,"fixdep: %s is empty\n",depfile);
  380. close(fd);
  381. return;
  382. }
  383. map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
  384. if ((long) map == -1) {
  385. perror("fixdep: mmap");
  386. close(fd);
  387. return;
  388. }
  389. parse_dep_file(map, st.st_size);
  390. munmap(map, st.st_size);
  391. close(fd);
  392. }
  393. static void traps(void)
  394. {
  395. static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
  396. int *p = (int *)test;
  397. if (*p != INT_CONF) {
  398. fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianness? %#x\n",
  399. *p);
  400. exit(2);
  401. }
  402. }
  403. int main(int argc, char *argv[])
  404. {
  405. traps();
  406. if (argc != 4)
  407. usage();
  408. depfile = argv[1];
  409. target = argv[2];
  410. cmdline = argv[3];
  411. print_cmdline();
  412. print_deps();
  413. return 0;
  414. }