fixdep.c 10 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. * 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. #include <sys/types.h>
  92. #include <sys/stat.h>
  93. #include <unistd.h>
  94. #include <fcntl.h>
  95. #include <string.h>
  96. #include <stdarg.h>
  97. #include <stdlib.h>
  98. #include <stdio.h>
  99. #include <ctype.h>
  100. char tmp_buf[256]; /* hack for U-Boot */
  101. static void usage(void)
  102. {
  103. fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
  104. exit(1);
  105. }
  106. /*
  107. * In the intended usage of this program, the stdout is redirected to .*.cmd
  108. * files. The return value of printf() and putchar() must be checked to catch
  109. * any error, e.g. "No space left on device".
  110. */
  111. static void xprintf(const char *format, ...)
  112. {
  113. va_list ap;
  114. int ret;
  115. va_start(ap, format);
  116. ret = vprintf(format, ap);
  117. if (ret < 0) {
  118. perror("fixdep");
  119. exit(1);
  120. }
  121. va_end(ap);
  122. }
  123. static void xputchar(int c)
  124. {
  125. int ret;
  126. ret = putchar(c);
  127. if (ret == EOF) {
  128. perror("fixdep");
  129. exit(1);
  130. }
  131. }
  132. /*
  133. * Print out a dependency path from a symbol name
  134. */
  135. static void print_dep(const char *m, int slen, const char *dir)
  136. {
  137. int c, prev_c = '/', i;
  138. xprintf(" $(wildcard %s/", dir);
  139. for (i = 0; i < slen; i++) {
  140. c = m[i];
  141. if (c == '_')
  142. c = '/';
  143. else
  144. c = tolower(c);
  145. if (c != '/' || prev_c != '/')
  146. xputchar(c);
  147. prev_c = c;
  148. }
  149. xprintf(".h) \\\n");
  150. }
  151. struct item {
  152. struct item *next;
  153. unsigned int len;
  154. unsigned int hash;
  155. char name[0];
  156. };
  157. #define HASHSZ 256
  158. static struct item *hashtab[HASHSZ];
  159. static unsigned int strhash(const char *str, unsigned int sz)
  160. {
  161. /* fnv32 hash */
  162. unsigned int i, hash = 2166136261U;
  163. for (i = 0; i < sz; i++)
  164. hash = (hash ^ str[i]) * 0x01000193;
  165. return hash;
  166. }
  167. /*
  168. * Lookup a value in the configuration string.
  169. */
  170. static int is_defined_config(const char *name, int len, unsigned int hash)
  171. {
  172. struct item *aux;
  173. for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {
  174. if (aux->hash == hash && aux->len == len &&
  175. memcmp(aux->name, name, len) == 0)
  176. return 1;
  177. }
  178. return 0;
  179. }
  180. /*
  181. * Add a new value to the configuration string.
  182. */
  183. static void define_config(const char *name, int len, unsigned int hash)
  184. {
  185. struct item *aux = malloc(sizeof(*aux) + len);
  186. if (!aux) {
  187. perror("fixdep:malloc");
  188. exit(1);
  189. }
  190. memcpy(aux->name, name, len);
  191. aux->len = len;
  192. aux->hash = hash;
  193. aux->next = hashtab[hash % HASHSZ];
  194. hashtab[hash % HASHSZ] = aux;
  195. }
  196. /*
  197. * Record the use of a CONFIG_* word.
  198. */
  199. static void use_config(const char *m, int slen)
  200. {
  201. unsigned int hash = strhash(m, slen);
  202. if (is_defined_config(m, slen, hash))
  203. return;
  204. define_config(m, slen, hash);
  205. print_dep(m, slen, "include/config");
  206. }
  207. /* test if s ends in sub */
  208. static int str_ends_with(const char *s, int slen, const char *sub)
  209. {
  210. int sublen = strlen(sub);
  211. if (sublen > slen)
  212. return 0;
  213. return !memcmp(s + slen - sublen, sub, sublen);
  214. }
  215. static void parse_config_file(const char *p)
  216. {
  217. const char *q, *r;
  218. const char *start = p;
  219. while ((p = strstr(p, "CONFIG_"))) {
  220. if (p > start && (isalnum(p[-1]) || p[-1] == '_')) {
  221. p += 7;
  222. continue;
  223. }
  224. p += 7;
  225. q = p;
  226. while (isalnum(*q) || *q == '_')
  227. q++;
  228. if (str_ends_with(p, q - p, "_MODULE"))
  229. r = q - 7;
  230. else
  231. r = q;
  232. /*
  233. * U-Boot also handles
  234. * CONFIG_IS_ENABLED(...)
  235. * CONFIG_VAL(...)
  236. */
  237. if ((q - p == 10 && !memcmp(p, "IS_ENABLED(", 11)) ||
  238. (q - p == 3 && !memcmp(p, "VAL(", 4))) {
  239. p = q + 1;
  240. q = p;
  241. while (isalnum(*q) || *q == '_')
  242. q++;
  243. r = q;
  244. if (r > p && tmp_buf[0]) {
  245. memcpy(tmp_buf + 4, p, r - p);
  246. r = tmp_buf + 4 + (r - p);
  247. p = tmp_buf;
  248. }
  249. }
  250. /* end U-Boot hack */
  251. if (r > p)
  252. use_config(p, r - p);
  253. p = q;
  254. }
  255. }
  256. static void *read_file(const char *filename)
  257. {
  258. struct stat st;
  259. int fd;
  260. char *buf;
  261. fd = open(filename, O_RDONLY);
  262. if (fd < 0) {
  263. fprintf(stderr, "fixdep: error opening file: ");
  264. perror(filename);
  265. exit(2);
  266. }
  267. if (fstat(fd, &st) < 0) {
  268. fprintf(stderr, "fixdep: error fstat'ing file: ");
  269. perror(filename);
  270. exit(2);
  271. }
  272. buf = malloc(st.st_size + 1);
  273. if (!buf) {
  274. perror("fixdep: malloc");
  275. exit(2);
  276. }
  277. if (read(fd, buf, st.st_size) != st.st_size) {
  278. perror("fixdep: read");
  279. exit(2);
  280. }
  281. buf[st.st_size] = '\0';
  282. close(fd);
  283. return buf;
  284. }
  285. /* Ignore certain dependencies */
  286. static int is_ignored_file(const char *s, int len)
  287. {
  288. return str_ends_with(s, len, "include/generated/autoconf.h") ||
  289. str_ends_with(s, len, "include/generated/autoksyms.h");
  290. }
  291. /*
  292. * Important: The below generated source_foo.o and deps_foo.o variable
  293. * assignments are parsed not only by make, but also by the rather simple
  294. * parser in scripts/mod/sumversion.c.
  295. */
  296. static void parse_dep_file(char *m, const char *target)
  297. {
  298. char *p;
  299. int is_last, is_target;
  300. int saw_any_target = 0;
  301. int is_first_dep = 0;
  302. void *buf;
  303. while (1) {
  304. /* Skip any "white space" */
  305. while (*m == ' ' || *m == '\\' || *m == '\n')
  306. m++;
  307. if (!*m)
  308. break;
  309. /* Find next "white space" */
  310. p = m;
  311. while (*p && *p != ' ' && *p != '\\' && *p != '\n')
  312. p++;
  313. is_last = (*p == '\0');
  314. /* Is the token we found a target name? */
  315. is_target = (*(p-1) == ':');
  316. /* Don't write any target names into the dependency file */
  317. if (is_target) {
  318. /* The /next/ file is the first dependency */
  319. is_first_dep = 1;
  320. } else if (!is_ignored_file(m, p - m)) {
  321. *p = '\0';
  322. /*
  323. * Do not list the source file as dependency, so that
  324. * kbuild is not confused if a .c file is rewritten
  325. * into .S or vice versa. Storing it in source_* is
  326. * needed for modpost to compute srcversions.
  327. */
  328. if (is_first_dep) {
  329. /*
  330. * If processing the concatenation of multiple
  331. * dependency files, only process the first
  332. * target name, which will be the original
  333. * source name, and ignore any other target
  334. * names, which will be intermediate temporary
  335. * files.
  336. */
  337. if (!saw_any_target) {
  338. saw_any_target = 1;
  339. xprintf("source_%s := %s\n\n",
  340. target, m);
  341. xprintf("deps_%s := \\\n", target);
  342. }
  343. is_first_dep = 0;
  344. } else {
  345. xprintf(" %s \\\n", m);
  346. }
  347. buf = read_file(m);
  348. parse_config_file(buf);
  349. free(buf);
  350. }
  351. if (is_last)
  352. break;
  353. /*
  354. * Start searching for next token immediately after the first
  355. * "whitespace" character that follows this token.
  356. */
  357. m = p + 1;
  358. }
  359. if (!saw_any_target) {
  360. fprintf(stderr, "fixdep: parse error; no targets found\n");
  361. exit(1);
  362. }
  363. xprintf("\n%s: $(deps_%s)\n\n", target, target);
  364. xprintf("$(deps_%s):\n", target);
  365. }
  366. int main(int argc, char *argv[])
  367. {
  368. const char *depfile, *target, *cmdline;
  369. void *buf;
  370. if (argc != 4)
  371. usage();
  372. depfile = argv[1];
  373. target = argv[2];
  374. cmdline = argv[3];
  375. /* hack for U-Boot */
  376. if (!strncmp(target, "spl/", 4))
  377. strcpy(tmp_buf, "SPL_");
  378. else if (!strncmp(target, "tpl/", 4))
  379. strcpy(tmp_buf, "TPL_");
  380. /* end U-Boot hack */
  381. xprintf("cmd_%s := %s\n\n", target, cmdline);
  382. buf = read_file(depfile);
  383. parse_dep_file(buf, target);
  384. free(buf);
  385. return 0;
  386. }