110420Salanb/* 212585Salanb * "Optimize" a list of dependencies as spit out by gcc -MD 310420Salanb * for the kernel build 410420Salanb * =========================================================================== 510420Salanb * 610420Salanb * Author Kai Germaschewski 710420Salanb * Copyright 2002 by Kai Germaschewski <kai.germaschewski@gmx.de> 810420Salanb * 910420Salanb * This software may be used and distributed according to the terms 1010420Salanb * of the GNU General Public License, incorporated herein by reference. 1110420Salanb * 1210420Salanb * 1310420Salanb * Introduction: 1410420Salanb * 1510420Salanb * gcc produces a very nice and correct list of dependencies which 1610420Salanb * tells make when to remake a file. 1710420Salanb * 1810420Salanb * To use this list as-is however has the drawback that virtually 1910420Salanb * every file in the kernel includes autoconf.h. 2010420Salanb * 2110420Salanb * If the user re-runs make *config, autoconf.h will be 2210420Salanb * regenerated. make notices that and will rebuild every file which 2310420Salanb * includes autoconf.h, i.e. basically all files. This is extremely 2410420Salanb * annoying if the user just changed CONFIG_HIS_DRIVER from n to m. 2510420Salanb * 2611098Sdsamersoff * So we play the same trick that "mkdep" played before. We replace 2711833Sctornqvi * the dependency on autoconf.h by a dependency on every config 2810420Salanb * option which is mentioned in any of the listed prerequisites. 2910420Salanb * 3010420Salanb * kconfig populates a tree in include/config/ with an empty file 3112723Salanb * for each config symbol and when the configuration is updated 3210420Salanb * the files representing changed config options are touched 3310420Salanb * which then let make pick up the changes and the files that use 3410420Salanb * the config symbols are rebuilt. 3510420Salanb * 3610420Salanb * So if the user changes his CONFIG_HIS_DRIVER option, only the objects 3710420Salanb * which depend on "include/config/HIS_DRIVER" will be rebuilt, 3810420Salanb * so most likely only his driver ;-) 3910420Salanb * 4010420Salanb * The idea above dates, by the way, back to Michael E Chastain, AFAIK. 4112585Salanb * 4212585Salanb * So to get dependencies right, there are two issues: 4310420Salanb * o if any of the files the compiler read changed, we need to rebuild 4412585Salanb * o if the command line given to the compile the file changed, we 4510420Salanb * better rebuild as well. 4612723Salanb * 4710420Salanb * The former is handled by using the -MD output, the later by saving 4812723Salanb * the command line used to compile the old object and comparing it 4912723Salanb * to the one we would now use. 5010420Salanb * 5110420Salanb * Again, also this idea is pretty old and has been discussed on 5210420Salanb * kbuild-devel a long time ago. I don't have a sensibly working 5310420Salanb * internet connection right now, so I rather don't mention names 5410420Salanb * without double checking. 5510420Salanb * 5612585Salanb * This code here has been based partially based on mkdep.c, which 5712585Salanb * says the following about its history: 5812585Salanb * 5912723Salanb * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>. 6010420Salanb * This is a C version of syncdep.pl by Werner Almesberger. 6110420Salanb * 6212585Salanb * 6312585Salanb * It is invoked as 6412585Salanb * 6512723Salanb * fixdep <depfile> <target> <cmdline> 6610420Salanb * 6712585Salanb * and will read the dependency file <depfile> 6812585Salanb * 6910420Salanb * The transformed dependency snipped is written to stdout. 7010420Salanb * 7110420Salanb * It first generates a line 7212585Salanb * 7310420Salanb * savedcmd_<target> = <cmdline> 7410420Salanb * 7510420Salanb * and then basically copies the .<target>.d file to stdout, in the 7610420Salanb * process filtering out the dependency on autoconf.h and adding 7712585Salanb * dependencies on include/config/MY_OPTION for every 7810420Salanb * CONFIG_MY_OPTION encountered in any of the prerequisites. 7910420Salanb * 8010420Salanb * We don't even try to really parse the header files, but 8110420Salanb * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will 8210420Salanb * be picked up as well. It's not a problem with respect to 8310420Salanb * correctness, since that can only give too many dependencies, thus 8410420Salanb * we cannot miss a rebuild. Since people tend to not mention totally 8510420Salanb * unrelated CONFIG_ options all over the place, it's not an 8610420Salanb * 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 102static void usage(void) 103{ 104 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n"); 105 exit(1); 106} 107 108struct item { 109 struct item *next; 110 unsigned int len; 111 unsigned int hash; 112 char name[]; 113}; 114 115#define HASHSZ 256 116static struct item *config_hashtab[HASHSZ], *file_hashtab[HASHSZ]; 117 118static 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 */ 131static void add_to_hashtable(const char *name, int len, unsigned int hash, 132 struct item *hashtab[]) 133{ 134 struct item *aux = malloc(sizeof(*aux) + len); 135 136 if (!aux) { 137 perror("fixdep:malloc"); 138 exit(1); 139 } 140 memcpy(aux->name, name, 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 */ 151static bool in_hashtable(const char *name, int len, struct item *hashtab[]) 152{ 153 struct item *aux; 154 unsigned int hash = strhash(name, len); 155 156 for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) { 157 if (aux->hash == hash && aux->len == len && 158 memcmp(aux->name, name, 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 */ 170static void use_config(const char *m, int slen) 171{ 172 if (in_hashtable(m, slen, config_hashtab)) 173 return; 174 175 /* Print out a dependency path from a symbol name. */ 176 printf(" $(wildcard include/config/%.*s) \\\n", slen, m); 177} 178 179/* test if s ends in sub */ 180static int str_ends_with(const char *s, int slen, const char *sub) 181{ 182 int sublen = strlen(sub); 183 184 if (sublen > slen) 185 return 0; 186 187 return !memcmp(s + slen - sublen, sub, sublen); 188} 189 190static void parse_config_file(const char *p) 191{ 192 const char *q, *r; 193 const char *start = p; 194 195 while ((p = strstr(p, "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(p, q - p, "_MODULE")) 205 r = q - 7; 206 else 207 r = q; 208 if (r > p) 209 use_config(p, r - p); 210 p = q; 211 } 212} 213 214static void *read_file(const char *filename) 215{ 216 struct stat st; 217 int fd; 218 char *buf; 219 220 fd = open(filename, O_RDONLY); 221 if (fd < 0) { 222 fprintf(stderr, "fixdep: error opening file: "); 223 perror(filename); 224 exit(2); 225 } 226 if (fstat(fd, &st) < 0) { 227 fprintf(stderr, "fixdep: error fstat'ing file: "); 228 perror(filename); 229 exit(2); 230 } 231 buf = malloc(st.st_size + 1); 232 if (!buf) { 233 perror("fixdep: malloc"); 234 exit(2); 235 } 236 if (read(fd, buf, st.st_size) != st.st_size) { 237 perror("fixdep: read"); 238 exit(2); 239 } 240 buf[st.st_size] = '\0'; 241 close(fd); 242 243 return buf; 244} 245 246/* Ignore certain dependencies */ 247static int is_ignored_file(const char *s, int len) 248{ 249 return str_ends_with(s, len, "include/generated/autoconf.h"); 250} 251 252/* Do not parse these files */ 253static 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, len, ".rlib") || 257 str_ends_with(s, len, ".rmeta") || 258 str_ends_with(s, len, ".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 */ 266static 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(p + 1, p, 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("source_%s := %s\n\n", target, p); 384 printf("deps_%s := \\\n", target); 385 need_parse = true; 386 } 387 } else if (!is_ignored_file(p, q - p) && 388 !in_hashtable(p, q - p, file_hashtab)) { 389 printf(" %s \\\n", p); 390 need_parse = true; 391 } 392 393 if (need_parse && !is_no_parse_file(p, q - p)) { 394 void *buf; 395 396 buf = read_file(p); 397 parse_config_file(buf); 398 free(buf); 399 } 400 401 is_source = false; 402 *q = saved_c; 403 p = q; 404 } 405 406 if (!saw_any_target) { 407 fprintf(stderr, "fixdep: parse error; no targets found\n"); 408 exit(1); 409 } 410 411 printf("\n%s: $(deps_%s)\n\n", target, target); 412 printf("$(deps_%s):\n", target); 413} 414 415int 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("savedcmd_%s := %s\n\n", target, cmdline); 428 429 buf = read_file(depfile); 430 parse_dep_file(buf, target); 431 free(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, "fixdep: not all data was written to the output\n"); 441 exit(1); 442 } 443 444 return 0; 445} 446