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 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.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 prerequisites.
  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. * We don't even try to really parse the header files, but
  86. * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will
  87. * be picked up as well. It's not a problem with respect to
  88. * correctness, since that can only give too many dependencies, thus
  89. * we cannot miss a rebuild. Since people tend to not mention totally
  90. * unrelated CONFIG_ options all over the place, it's not an
  91. * efficiency problem either.
  92. *
  93. * (Note: it'd be easy to port over the complete mkdep state machine,
  94. * but I don't think the added complexity is worth it)
  95. */
  96. #include <sys/types.h>
  97. #include <sys/stat.h>
  98. #include <unistd.h>
  99. #include <fcntl.h>
  100. #include <string.h>
  101. #include <stdlib.h>
  102. #include <stdio.h>
  103. #include <ctype.h>
  104. int is_spl_build = 0; /* hack for U-Boot */
  105. static void usage(void)
  106. {
  107. fprintf(stderr, "Usage: fixdep [-e] <depfile> <target> <cmdline>\n");
  108. fprintf(stderr, " -e insert extra dependencies given on stdin\n");
  109. exit(1);
  110. }
  111. /*
  112. * Print out a dependency path from a symbol name
  113. */
  114. static void print_dep(const char *m, int slen, const char *dir)
  115. {
  116. int c, prev_c = '/', i;
  117. printf(" $(wildcard %s/", dir);
  118. for (i = 0; i < slen; i++) {
  119. c = m[i];
  120. if (c == '_')
  121. c = '/';
  122. else
  123. c = tolower(c);
  124. if (c != '/' || prev_c != '/')
  125. putchar(c);
  126. prev_c = c;
  127. }
  128. printf(".h) \\\n");
  129. }
  130. static void do_extra_deps(void)
  131. {
  132. char buf[80];
  133. while (fgets(buf, sizeof(buf), stdin)) {
  134. int len = strlen(buf);
  135. if (len < 2 || buf[len - 1] != '\n') {
  136. fprintf(stderr, "fixdep: bad data on stdin\n");
  137. exit(1);
  138. }
  139. print_dep(buf, len - 1, "include/ksym");
  140. }
  141. }
  142. struct item {
  143. struct item *next;
  144. unsigned int len;
  145. unsigned int hash;
  146. char name[0];
  147. };
  148. #define HASHSZ 256
  149. static struct item *hashtab[HASHSZ];
  150. static unsigned int strhash(const char *str, unsigned int sz)
  151. {
  152. /* fnv32 hash */
  153. unsigned int i, hash = 2166136261U;
  154. for (i = 0; i < sz; i++)
  155. hash = (hash ^ str[i]) * 0x01000193;
  156. return hash;
  157. }
  158. /*
  159. * Lookup a value in the configuration string.
  160. */
  161. static int is_defined_config(const char *name, int len, unsigned int hash)
  162. {
  163. struct item *aux;
  164. for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {
  165. if (aux->hash == hash && aux->len == len &&
  166. memcmp(aux->name, name, len) == 0)
  167. return 1;
  168. }
  169. return 0;
  170. }
  171. /*
  172. * Add a new value to the configuration string.
  173. */
  174. static void define_config(const char *name, int len, unsigned int hash)
  175. {
  176. struct item *aux = malloc(sizeof(*aux) + len);
  177. if (!aux) {
  178. perror("fixdep:malloc");
  179. exit(1);
  180. }
  181. memcpy(aux->name, name, len);
  182. aux->len = len;
  183. aux->hash = hash;
  184. aux->next = hashtab[hash % HASHSZ];
  185. hashtab[hash % HASHSZ] = aux;
  186. }
  187. /*
  188. * Record the use of a CONFIG_* word.
  189. */
  190. static void use_config(const char *m, int slen)
  191. {
  192. unsigned int hash = strhash(m, slen);
  193. if (is_defined_config(m, slen, hash))
  194. return;
  195. define_config(m, slen, hash);
  196. print_dep(m, slen, "include/config");
  197. }
  198. /* test if s ends in sub */
  199. static int str_ends_with(const char *s, int slen, const char *sub)
  200. {
  201. int sublen = strlen(sub);
  202. if (sublen > slen)
  203. return 0;
  204. return !memcmp(s + slen - sublen, sub, sublen);
  205. }
  206. static void parse_config_file(const char *p)
  207. {
  208. const char *q, *r;
  209. const char *start = p;
  210. char tmp_buf[256] = "SPL_"; /* hack for U-Boot */
  211. while ((p = strstr(p, "CONFIG_"))) {
  212. if (p > start && (isalnum(p[-1]) || p[-1] == '_')) {
  213. p += 7;
  214. continue;
  215. }
  216. p += 7;
  217. q = p;
  218. while (*q && (isalnum(*q) || *q == '_'))
  219. q++;
  220. if (str_ends_with(p, q - p, "_MODULE"))
  221. r = q - 7;
  222. else
  223. r = q;
  224. /*
  225. * U-Boot also handles
  226. * CONFIG_IS_ENABLED(...)
  227. * CONFIG_IS_BUILTIN(...)
  228. * CONFIG_IS_MODULE(...)
  229. * CONFIG_VAL(...)
  230. */
  231. if ((q - p == 10 && !memcmp(p, "IS_ENABLED(", 11)) ||
  232. (q - p == 10 && !memcmp(p, "IS_BUILTIN(", 11)) ||
  233. (q - p == 9 && !memcmp(p, "IS_MODULE(", 10)) ||
  234. (q - p == 3 && !memcmp(p, "VAL(", 4))) {
  235. p = q + 1;
  236. while (isalnum(*q) || *q == '_')
  237. q++;
  238. r = q;
  239. if (r > p && is_spl_build) {
  240. memcpy(tmp_buf + 4, p, r - p);
  241. r = tmp_buf + 4 + (r - p);
  242. p = tmp_buf;
  243. }
  244. }
  245. /* end U-Boot hack */
  246. if (r > p)
  247. use_config(p, r - p);
  248. p = q;
  249. }
  250. }
  251. static void *read_file(const char *filename)
  252. {
  253. struct stat st;
  254. int fd;
  255. char *buf;
  256. fd = open(filename, O_RDONLY);
  257. if (fd < 0) {
  258. fprintf(stderr, "fixdep: error opening file: ");
  259. perror(filename);
  260. exit(2);
  261. }
  262. if (fstat(fd, &st) < 0) {
  263. fprintf(stderr, "fixdep: error fstat'ing file: ");
  264. perror(filename);
  265. exit(2);
  266. }
  267. buf = malloc(st.st_size + 1);
  268. if (!buf) {
  269. perror("fixdep: malloc");
  270. exit(2);
  271. }
  272. if (read(fd, buf, st.st_size) != st.st_size) {
  273. perror("fixdep: read");
  274. exit(2);
  275. }
  276. buf[st.st_size] = '\0';
  277. close(fd);
  278. return buf;
  279. }
  280. /* Ignore certain dependencies */
  281. static int is_ignored_file(const char *s, int len)
  282. {
  283. return str_ends_with(s, len, "include/generated/autoconf.h") ||
  284. str_ends_with(s, len, "include/generated/autoksyms.h") ||
  285. str_ends_with(s, len, ".ver");
  286. }
  287. /*
  288. * Important: The below generated source_foo.o and deps_foo.o variable
  289. * assignments are parsed not only by make, but also by the rather simple
  290. * parser in scripts/mod/sumversion.c.
  291. */
  292. static void parse_dep_file(char *m, const char *target, int insert_extra_deps)
  293. {
  294. char *p;
  295. int is_last, is_target;
  296. int saw_any_target = 0;
  297. int is_first_dep = 0;
  298. void *buf;
  299. while (1) {
  300. /* Skip any "white space" */
  301. while (*m == ' ' || *m == '\\' || *m == '\n')
  302. m++;
  303. if (!*m)
  304. break;
  305. /* Find next "white space" */
  306. p = m;
  307. while (*p && *p != ' ' && *p != '\\' && *p != '\n')
  308. p++;
  309. is_last = (*p == '\0');
  310. /* Is the token we found a target name? */
  311. is_target = (*(p-1) == ':');
  312. /* Don't write any target names into the dependency file */
  313. if (is_target) {
  314. /* The /next/ file is the first dependency */
  315. is_first_dep = 1;
  316. } else if (!is_ignored_file(m, p - m)) {
  317. *p = '\0';
  318. /*
  319. * Do not list the source file as dependency, so that
  320. * kbuild is not confused if a .c file is rewritten
  321. * into .S or vice versa. Storing it in source_* is
  322. * needed for modpost to compute srcversions.
  323. */
  324. if (is_first_dep) {
  325. /*
  326. * If processing the concatenation of multiple
  327. * dependency files, only process the first
  328. * target name, which will be the original
  329. * source name, and ignore any other target
  330. * names, which will be intermediate temporary
  331. * files.
  332. */
  333. if (!saw_any_target) {
  334. saw_any_target = 1;
  335. printf("source_%s := %s\n\n",
  336. target, m);
  337. printf("deps_%s := \\\n", target);
  338. }
  339. is_first_dep = 0;
  340. } else {
  341. printf(" %s \\\n", m);
  342. }
  343. buf = read_file(m);
  344. parse_config_file(buf);
  345. free(buf);
  346. }
  347. if (is_last)
  348. break;
  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. if (insert_extra_deps)
  360. do_extra_deps();
  361. printf("\n%s: $(deps_%s)\n\n", target, target);
  362. printf("$(deps_%s):\n", target);
  363. }
  364. int main(int argc, char *argv[])
  365. {
  366. const char *depfile, *target, *cmdline;
  367. int insert_extra_deps = 0;
  368. void *buf;
  369. if (argc == 5 && !strcmp(argv[1], "-e")) {
  370. insert_extra_deps = 1;
  371. argv++;
  372. } else if (argc != 4)
  373. usage();
  374. depfile = argv[1];
  375. target = argv[2];
  376. cmdline = argv[3];
  377. /* hack for U-Boot */
  378. if (!strncmp(target, "spl/", 4) || !strncmp(target, "tpl/", 4))
  379. is_spl_build = 1;
  380. printf("cmd_%s := %s\n\n", target, cmdline);
  381. buf = read_file(depfile);
  382. parse_dep_file(buf, target, insert_extra_deps);
  383. free(buf);
  384. return 0;
  385. }