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 <linux/config.h> which then again 20 * includes <linux/autoconf.h> 21 * 22 * If the user re-runs make *config, linux/autoconf.h will be 23 * regenerated. make notices that and will rebuild every file which 24 * includes autoconf.h, i.e. basically all files. This is extremely 25 * annoying if the user just changed CONFIG_HIS_DRIVER from n to m. 26 * 27 * So we play the same trick that "mkdep" played before. We replace 28 * the dependency on linux/autoconf.h by a dependency on every config 29 * option which is mentioned in any of the listed prequisites. 30 * 31 * To be exact, split-include populates a tree in include/config/, 32 * e.g. include/config/his/driver.h, which contains the #define/#undef 33 * for the CONFIG_HIS_DRIVER option. 34 * 35 * So if the user changes his CONFIG_HIS_DRIVER option, only the objects 36 * which depend on "include/linux/config/his/driver.h" will be rebuilt, 37 * so most likely only his driver ;-) 38 * 39 * The idea above dates, by the way, back to Michael E Chastain, AFAIK. 40 * 41 * So to get dependencies right, there are two issues: 42 * o if any of the files the compiler read changed, we need to rebuild 43 * o if the command line given to the compile the file changed, we 44 * better rebuild as well. 45 * 46 * The former is handled by using the -MD output, the later by saving 47 * the command line used to compile the old object and comparing it 48 * to the one we would now use. 49 * 50 * Again, also this idea is pretty old and has been discussed on 51 * kbuild-devel a long time ago. I don't have a sensibly working 52 * internet connection right now, so I rather don't mention names 53 * without double checking. 54 * 55 * This code here has been based partially based on mkdep.c, which 56 * says the following about its history: 57 * 58 * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>. 59 * This is a C version of syncdep.pl by Werner Almesberger. 60 * 61 * 62 * It is invoked as 63 * 64 * fixdep <depfile> <target> <cmdline> 65 * 66 * and will read the dependency file <depfile> 67 * 68 * The transformed dependency snipped is written to stdout. 69 * 70 * It first generates a line 71 * 72 * cmd_<target> = <cmdline> 73 * 74 * and then basically copies the .<target>.d file to stdout, in the 75 * process filtering out the dependency on linux/autoconf.h and adding 76 * dependencies on include/config/my/option.h for every 77 * CONFIG_MY_OPTION encountered in any of the prequisites. 78 * 79 * It will also filter out all the dependencies on *.ver. We need 80 * to make sure that the generated version checksum are globally up 81 * to date before even starting the recursive build, so it's too late 82 * at this point anyway. 83 * 84 * The algorithm to grep for "CONFIG_..." is bit unusual, but should 85 * be fast ;-) 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/* 97 * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto 98 * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not 99 * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as 100 * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h, 101 * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that 102 * those files will have correct dependencies. 103 */ 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> 116 117/* bbox: not needed 118#define INT_CONF ntohl(0x434f4e46) 119#define INT_ONFI ntohl(0x4f4e4649) 120#define INT_NFIG ntohl(0x4e464947) 121#define INT_FIG_ ntohl(0x4649475f) 122*/ 123 124char *target; 125char *depfile; 126char *cmdline; 127 128void usage(void) 129 130{ 131 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n"); 132 exit(1); 133} 134 135/* 136 * Print out the commandline prefixed with cmd_<target filename> := 137 */ 138void print_cmdline(void) 139{ 140 printf("cmd_%s := %s\n\n", target, cmdline); 141} 142 143char * str_config = NULL; 144int size_config = 0; 145int len_config = 0; 146 147/* 148 * Grow the configuration string to a desired length. 149 * Usually the first growth is plenty. 150 */ 151void grow_config(int len) 152{ 153 while (len_config + len > size_config) { 154 if (size_config == 0) 155 size_config = 2048; 156 str_config = realloc(str_config, size_config *= 2); 157 if (str_config == NULL) 158 { perror("fixdep:malloc"); exit(1); } 159 } 160} 161 162 163 164/* 165 * Lookup a value in the configuration string. 166 */ 167int is_defined_config(const char * name, int len) 168{ 169 const char * pconfig; 170 const char * plast = str_config + len_config - len; 171 for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) { 172 if (pconfig[ -1] == '\n' 173 && pconfig[len] == '\n' 174 && !memcmp(pconfig, name, len)) 175 return 1; 176 } 177 return 0; 178} 179 180/* 181 * Add a new value to the configuration string. 182 */ 183void define_config(const char * name, int len) 184{ 185 grow_config(len + 1); 186 187 memcpy(str_config+len_config, name, len); 188 len_config += len; 189 str_config[len_config++] = '\n'; 190} 191 192/* 193 * Clear the set of configuration strings. 194 */ 195void clear_config(void) 196{ 197 len_config = 0; 198 define_config("", 0); 199} 200 201/* 202 * Record the use of a CONFIG_* word. 203 */ 204void use_config(char *m, int slen) 205{ 206 char *s = alloca(slen+1); 207 char *p; 208 209 if (is_defined_config(m, slen)) 210 return; 211 212 define_config(m, slen); 213 214 memcpy(s, m, slen); s[slen] = 0; 215 216 for (p = s; p < s + slen; p++) { 217 if (*p == '_') 218 *p = '/'; 219 else 220 *p = tolower((int)*p); 221 } 222 printf(" $(wildcard include/config/%s.h) \\\n", s); 223} 224 225void parse_config_file(char *map, size_t len) 226{ 227 /* modified for bbox */ 228 char *end_3 = map + len - 3; /* 3 == length of "IF_" */ 229 char *end_7 = map + len - 7; 230 char *p = map; 231 char *q; 232 int off; 233 234 for (; p <= end_3; p++) { 235 /* Find next identifier's beginning */ 236 if (!(isalnum(*p) || *p == '_')) 237 continue; 238 239 /* Check it */ 240 if (p < end_7 && p[6] == '_') { 241 if (!memcmp(p, "CONFIG", 6)) goto conf7; 242 if (!memcmp(p, "ENABLE", 6)) goto conf7; 243 if (!memcmp(p, "IF_NOT", 6)) goto conf7; 244 } 245 /* we have at least 3 chars because of p <= end_3 */ 246 /*if (!memcmp(p, "IF_", 3)) ...*/ 247 if (p[0] == 'I' && p[1] == 'F' && p[2] == '_') { 248 off = 3; 249 goto conf; 250 } 251 252 /* This identifier is not interesting, skip it */ 253 while (p <= end_3 && (isalnum(*p) || *p == '_')) 254 p++; 255 continue; 256 257 conf7: off = 7; 258 conf: 259 p += off; 260 for (q = p; q < end_3+3; q++) { 261 if (!(isalnum(*q) || *q == '_')) 262 break; 263 } 264 if (q != p) { 265 use_config(p, q-p); 266 } 267 } 268} 269 270/* test is s ends in sub */ 271int strrcmp(char *s, char *sub) 272{ 273 int slen = strlen(s); 274 int sublen = strlen(sub); 275 276 if (sublen > slen) 277 return 1; 278 279 return memcmp(s + slen - sublen, sub, sublen); 280} 281 282void do_config_file(char *filename) 283{ 284 struct stat st; 285 int fd; 286 void *map; 287 288 fd = open(filename, O_RDONLY); 289 if (fd < 0) { 290 fprintf(stderr, "fixdep: "); 291 perror(filename); 292 exit(2); 293 } 294 fstat(fd, &st); 295 if (st.st_size == 0) { 296 close(fd); 297 return; 298 } 299 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 300 if ((long) map == -1) { 301 perror("fixdep: mmap"); 302 close(fd); 303 return; 304 } 305 306 parse_config_file(map, st.st_size); 307 308 munmap(map, st.st_size); 309 310 close(fd); 311} 312 313void parse_dep_file(void *map, size_t len) 314{ 315 char *m = map; 316 char *end = m + len; 317 char *p; 318 char *s = alloca(len); 319 320 p = memchr(m, ':', len); 321 if (!p) { 322 fprintf(stderr, "fixdep: parse error\n"); 323 exit(1); 324 } 325 memcpy(s, m, p-m); s[p-m] = 0; 326 printf("deps_%s := \\\n", target); 327 m = p+1; 328 329 clear_config(); 330 331 while (m < end) { 332 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) 333 m++; 334 p = m; 335 while (p < end && *p != ' ') p++; 336 if (p == end) { 337 do p--; while (!isalnum(*p)); 338 p++; 339 } 340 memcpy(s, m, p-m); s[p-m] = 0; 341 if (strrcmp(s, "include/autoconf.h") && 342 strrcmp(s, "arch/um/include/uml-config.h") && 343 strrcmp(s, ".ver")) { 344 printf(" %s \\\n", s); 345 do_config_file(s); 346 } 347 m = p + 1; 348 } 349 printf("\n%s: $(deps_%s)\n\n", target, target); 350 printf("$(deps_%s):\n", target); 351} 352 353void print_deps(void) 354{ 355 struct stat st; 356 int fd; 357 void *map; 358 359 fd = open(depfile, O_RDONLY); 360 if (fd < 0) { 361 fprintf(stderr, "fixdep: "); 362 perror(depfile); 363 exit(2); 364 } 365 fstat(fd, &st); 366 if (st.st_size == 0) { 367 fprintf(stderr,"fixdep: %s is empty\n",depfile); 368 close(fd); 369 return; 370 } 371 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 372 if ((long) map == -1) { 373 perror("fixdep: mmap"); 374 close(fd); 375 return; 376 } 377 378 parse_dep_file(map, st.st_size); 379 380 munmap(map, st.st_size); 381 382 close(fd); 383} 384 385void traps(void) 386{ 387/* bbox: not needed 388 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF"; 389 390 if (*(int *)test != INT_CONF) { 391 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n", 392 *(int *)test); 393 exit(2); 394 } 395*/ 396} 397 398int main(int argc, char **argv) 399{ 400 traps(); 401 402 if (argc != 4) 403 usage(); 404 405 depfile = argv[1]; 406 target = argv[2]; 407 cmdline = argv[3]; 408 409 print_cmdline(); 410 print_deps(); 411 412 return 0; 413} 414