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 */ 136 void print_cmdline(void) 137 { 138 printf("cmd_%s := %s\n\n", target, cmdline); 139 } 140 141 char * str_config = NULL; 142 int size_config = 0; 143 int len_config = 0; 144 145 /* 146 * Grow the configuration string to a desired length. 147 * Usually the first growth is plenty. 148 */ 149 void grow_config(int len) 150 { 151 while (len_config + len > size_config) { 152 if (size_config == 0) 153 size_config = 2048; 154 str_config = realloc(str_config, size_config *= 2); 155 if (str_config == NULL) 156 { perror("fixdep:malloc"); exit(1); } 157 } 158 } 159 160 161 162 /* 163 * Lookup a value in the configuration string. 164 */ 165 int is_defined_config(const char * name, int len) 166 { 167 const char * pconfig; 168 const char * plast = str_config + len_config - len; 169 for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) { 170 if (pconfig[ -1] == '\n' 171 && pconfig[len] == '\n' 172 && !memcmp(pconfig, name, len)) 173 return 1; 174 } 175 return 0; 176 } 177 178 /* 179 * Add a new value to the configuration string. 180 */ 181 void define_config(const char * name, int len) 182 { 183 grow_config(len + 1); 184 185 memcpy(str_config+len_config, name, len); 186 len_config += len; 187 str_config[len_config++] = '\n'; 188 } 189 190 /* 191 * Clear the set of configuration strings. 192 */ 193 void clear_config(void) 194 { 195 len_config = 0; 196 define_config("", 0); 197 } 198 199 /* 200 * Record the use of a CONFIG_* word. 201 */ 202 void use_config(char *m, int slen) 203 { 204 char s[PATH_MAX]; 205 char *p; 206 207 if (is_defined_config(m, slen)) 208 return; 209 210 define_config(m, slen); 211 212 memcpy(s, m, slen); s[slen] = 0; 213 214 for (p = s; p < s + slen; p++) { 215 if (*p == '_') 216 *p = '/'; 217 else 218 *p = tolower((int)*p); 219 } 220 printf(" $(wildcard include/config/%s.h) \\\n", s); 221 } 222 223 void parse_config_file(char *map, size_t len) 224 { 225 int *end = (int *) (map + len); 226 /* start at +1, so that p can never be < map */ 227 int *m = (int *) map + 1; 228 char *p, *q; 229 230 for (; m < end; m++) { 231 if (*m == INT_CONF) { p = (char *) m ; goto conf; } 232 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; } 233 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; } 234 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; } 235 continue; 236 conf: 237 if (p > map + len - 7) 238 continue; 239 if (memcmp(p, "CONFIG_", 7)) 240 continue; 241 for (q = p + 7; q < map + len; q++) { 242 if (!(isalnum(*q) || *q == '_')) 243 goto found; 244 } 245 continue; 246 247 found: 248 use_config(p+7, q-p-7); 249 } 250 } 251 252 /* test is s ends in sub */ 253 int strrcmp(char *s, char *sub) 254 { 255 int slen = strlen(s); 256 int sublen = strlen(sub); 257 258 if (sublen > slen) 259 return 1; 260 261 return memcmp(s + slen - sublen, sub, sublen); 262 } 263 264 void do_config_file(char *filename) 265 { 266 struct stat st; 267 int fd; 268 void *map; 269 270 fd = open(filename, O_RDONLY); 271 if (fd < 0) { 272 fprintf(stderr, "fixdep: "); 273 perror(filename); 274 exit(2); 275 } 276 fstat(fd, &st); 277 if (st.st_size == 0) { 278 close(fd); 279 return; 280 } 281 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 282 if ((long) map == -1) { 283 perror("fixdep: mmap"); 284 close(fd); 285 return; 286 } 287 288 parse_config_file(map, st.st_size); 289 290 munmap(map, st.st_size); 291 292 close(fd); 293 } 294 295 void parse_dep_file(void *map, size_t len) 296 { 297 char *m = map; 298 char *end = m + len; 299 char *p; 300 char s[PATH_MAX]; 301 302 p = strchr(m, ':'); 303 if (!p) { 304 fprintf(stderr, "fixdep: parse error\n"); 305 exit(1); 306 } 307 memcpy(s, m, p-m); s[p-m] = 0; 308 printf("deps_%s := \\\n", target); 309 m = p+1; 310 311 clear_config(); 312 313 while (m < end) { 314 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) 315 m++; 316 p = m; 317 while (p < end && *p != ' ') p++; 318 if (p == end) { 319 do p--; while (!isalnum(*p)); 320 p++; 321 } 322 memcpy(s, m, p-m); s[p-m] = 0; 323 if (strrcmp(s, "include/linux/autoconf.h") && 324 strrcmp(s, "arch/um/include/uml-config.h") && 325 strrcmp(s, ".ver")) { 326 printf(" %s \\\n", s); 327 do_config_file(s); 328 } 329 m = p + 1; 330 } 331 printf("\n%s: $(deps_%s)\n\n", target, target); 332 printf("$(deps_%s):\n", target); 333 } 334 335 void print_deps(void) 336 { 337 struct stat st; 338 int fd; 339 void *map; 340 341 fd = open(depfile, O_RDONLY); 342 if (fd < 0) { 343 fprintf(stderr, "fixdep: "); 344 perror(depfile); 345 exit(2); 346 } 347 fstat(fd, &st); 348 if (st.st_size == 0) { 349 fprintf(stderr,"fixdep: %s is empty\n",depfile); 350 close(fd); 351 return; 352 } 353 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 354 if ((long) map == -1) { 355 perror("fixdep: mmap"); 356 close(fd); 357 return; 358 } 359 360 parse_dep_file(map, st.st_size); 361 362 munmap(map, st.st_size); 363 364 close(fd); 365 } 366 367 void traps(void) 368 { 369 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF"; 370 371 if (*(int *)test != INT_CONF) { 372 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n", 373 *(int *)test); 374 exit(2); 375 } 376 } 377 378 int main(int argc, char *argv[]) 379 { 380 traps(); 381 382 if (argc != 4) 383 usage(); 384 385 depfile = argv[1]; 386 target = argv[2]; 387 cmdline = argv[3]; 388 389 print_cmdline(); 390 print_deps(); 391 392 return 0; 393 } 394