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 #define INT_CONF ntohl(0x434f4e46) 118 #define INT_ONFI ntohl(0x4f4e4649) 119 #define INT_NFIG ntohl(0x4e464947) 120 #define INT_FIG_ ntohl(0x4649475f) 121 122 char *target; 123 char *depfile; 124 char *cmdline; 125 126 void usage(void) 127 128 { 129 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n"); 130 exit(1); 131 } 132 133 /* 134 * Print out the commandline prefixed with cmd_<target filename> := 135 * If commandline contains '#' escape with '\' so make to not see 136 * the '#' as a start-of-comment symbol 137 **/ 138 void print_cmdline(void) 139 { 140 char *p = cmdline; 141 142 printf("cmd_%s := ", target); 143 for (; *p; p++) { 144 if (*p == '#') 145 printf("\\"); 146 printf("%c", *p); 147 } 148 printf("\n\n"); 149 } 150 151 char * str_config = NULL; 152 int size_config = 0; 153 int len_config = 0; 154 155 /* 156 * Grow the configuration string to a desired length. 157 * Usually the first growth is plenty. 158 */ 159 void grow_config(int len) 160 { 161 while (len_config + len > size_config) { 162 if (size_config == 0) 163 size_config = 2048; 164 str_config = realloc(str_config, size_config *= 2); 165 if (str_config == NULL) 166 { perror("fixdep:malloc"); exit(1); } 167 } 168 } 169 170 171 172 /* 173 * Lookup a value in the configuration string. 174 */ 175 int is_defined_config(const char * name, int len) 176 { 177 const char * pconfig; 178 const char * plast = str_config + len_config - len; 179 for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) { 180 if (pconfig[ -1] == '\n' 181 && pconfig[len] == '\n' 182 && !memcmp(pconfig, name, len)) 183 return 1; 184 } 185 return 0; 186 } 187 188 /* 189 * Add a new value to the configuration string. 190 */ 191 void define_config(const char * name, int len) 192 { 193 grow_config(len + 1); 194 195 memcpy(str_config+len_config, name, len); 196 len_config += len; 197 str_config[len_config++] = '\n'; 198 } 199 200 /* 201 * Clear the set of configuration strings. 202 */ 203 void clear_config(void) 204 { 205 len_config = 0; 206 define_config("", 0); 207 } 208 209 /* 210 * Record the use of a CONFIG_* word. 211 */ 212 void use_config(char *m, int slen) 213 { 214 char s[PATH_MAX]; 215 char *p; 216 217 if (is_defined_config(m, slen)) 218 return; 219 220 define_config(m, slen); 221 222 memcpy(s, m, slen); s[slen] = 0; 223 224 for (p = s; p < s + slen; p++) { 225 if (*p == '_') 226 *p = '/'; 227 else 228 *p = tolower((int)*p); 229 } 230 printf(" $(wildcard include/config/%s.h) \\\n", s); 231 } 232 233 void parse_config_file(char *map, size_t len) 234 { 235 int *end = (int *) (map + len); 236 /* start at +1, so that p can never be < map */ 237 int *m = (int *) map + 1; 238 char *p, *q; 239 240 for (; m < end; m++) { 241 if (*m == INT_CONF) { p = (char *) m ; goto conf; } 242 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; } 243 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; } 244 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; } 245 continue; 246 conf: 247 if (p > map + len - 7) 248 continue; 249 if (memcmp(p, "CONFIG_", 7)) 250 continue; 251 for (q = p + 7; q < map + len; q++) { 252 if (!(isalnum(*q) || *q == '_')) 253 goto found; 254 } 255 continue; 256 257 found: 258 use_config(p+7, q-p-7); 259 } 260 } 261 262 /* test is s ends in sub */ 263 int strrcmp(char *s, char *sub) 264 { 265 int slen = strlen(s); 266 int sublen = strlen(sub); 267 268 if (sublen > slen) 269 return 1; 270 271 return memcmp(s + slen - sublen, sub, sublen); 272 } 273 274 void do_config_file(char *filename) 275 { 276 struct stat st; 277 int fd; 278 void *map; 279 280 fd = open(filename, O_RDONLY); 281 if (fd < 0) { 282 fprintf(stderr, "fixdep: "); 283 perror(filename); 284 exit(2); 285 } 286 fstat(fd, &st); 287 if (st.st_size == 0) { 288 close(fd); 289 return; 290 } 291 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 292 if ((long) map == -1) { 293 perror("fixdep: mmap"); 294 close(fd); 295 return; 296 } 297 298 parse_config_file(map, st.st_size); 299 300 munmap(map, st.st_size); 301 302 close(fd); 303 } 304 305 void parse_dep_file(void *map, size_t len) 306 { 307 char *m = map; 308 char *end = m + len; 309 char *p; 310 char s[PATH_MAX]; 311 312 p = strchr(m, ':'); 313 if (!p) { 314 fprintf(stderr, "fixdep: parse error\n"); 315 exit(1); 316 } 317 memcpy(s, m, p-m); s[p-m] = 0; 318 printf("deps_%s := \\\n", target); 319 m = p+1; 320 321 clear_config(); 322 323 while (m < end) { 324 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) 325 m++; 326 p = m; 327 while (p < end && *p != ' ') p++; 328 if (p == end) { 329 do p--; while (!isalnum(*p)); 330 p++; 331 } 332 memcpy(s, m, p-m); s[p-m] = 0; 333 if (strrcmp(s, "include/linux/autoconf.h") && 334 strrcmp(s, "arch/um/include/uml-config.h") && 335 strrcmp(s, ".ver")) { 336 printf(" %s \\\n", s); 337 do_config_file(s); 338 } 339 m = p + 1; 340 } 341 printf("\n%s: $(deps_%s)\n\n", target, target); 342 printf("$(deps_%s):\n", target); 343 } 344 345 void print_deps(void) 346 { 347 struct stat st; 348 int fd; 349 void *map; 350 351 fd = open(depfile, O_RDONLY); 352 if (fd < 0) { 353 fprintf(stderr, "fixdep: "); 354 perror(depfile); 355 exit(2); 356 } 357 fstat(fd, &st); 358 if (st.st_size == 0) { 359 fprintf(stderr,"fixdep: %s is empty\n",depfile); 360 close(fd); 361 return; 362 } 363 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 364 if ((long) map == -1) { 365 perror("fixdep: mmap"); 366 close(fd); 367 return; 368 } 369 370 parse_dep_file(map, st.st_size); 371 372 munmap(map, st.st_size); 373 374 close(fd); 375 } 376 377 void traps(void) 378 { 379 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF"; 380 381 if (*(int *)test != INT_CONF) { 382 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n", 383 *(int *)test); 384 exit(2); 385 } 386 } 387 388 int main(int argc, char *argv[]) 389 { 390 traps(); 391 392 if (argc != 4) 393 usage(); 394 395 depfile = argv[1]; 396 target = argv[2]; 397 cmdline = argv[3]; 398 399 print_cmdline(); 400 print_deps(); 401 402 return 0; 403 } 404