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 void print_cmdline(void) 134 { 135 printf("cmd_%s := %s\n\n", target, cmdline); 136 } 137 138 char * str_config = NULL; 139 int size_config = 0; 140 int len_config = 0; 141 142 /* 143 * Grow the configuration string to a desired length. 144 * Usually the first growth is plenty. 145 */ 146 void grow_config(int len) 147 { 148 while (len_config + len > size_config) { 149 if (size_config == 0) 150 size_config = 2048; 151 str_config = realloc(str_config, size_config *= 2); 152 if (str_config == NULL) 153 { perror("fixdep:malloc"); exit(1); } 154 } 155 } 156 157 158 159 /* 160 * Lookup a value in the configuration string. 161 */ 162 int is_defined_config(const char * name, int len) 163 { 164 const char * pconfig; 165 const char * plast = str_config + len_config - len; 166 for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) { 167 if (pconfig[ -1] == '\n' 168 && pconfig[len] == '\n' 169 && !memcmp(pconfig, name, len)) 170 return 1; 171 } 172 return 0; 173 } 174 175 /* 176 * Add a new value to the configuration string. 177 */ 178 void define_config(const char * name, int len) 179 { 180 grow_config(len + 1); 181 182 memcpy(str_config+len_config, name, len); 183 len_config += len; 184 str_config[len_config++] = '\n'; 185 } 186 187 /* 188 * Clear the set of configuration strings. 189 */ 190 void clear_config(void) 191 { 192 len_config = 0; 193 define_config("", 0); 194 } 195 196 /* 197 * Record the use of a CONFIG_* word. 198 */ 199 void use_config(char *m, int slen) 200 { 201 char s[PATH_MAX]; 202 char *p; 203 204 if (is_defined_config(m, slen)) 205 return; 206 207 define_config(m, slen); 208 209 memcpy(s, m, slen); s[slen] = 0; 210 211 for (p = s; p < s + slen; p++) { 212 if (*p == '_') 213 *p = '/'; 214 else 215 *p = tolower((unsigned char)*p); 216 } 217 printf(" $(wildcard include/config/%s.h) \\\n", s); 218 } 219 220 void parse_config_file(signed char *map, size_t len) 221 { 222 int *end = (int *) (map + len); 223 /* start at +1, so that p can never be < map */ 224 int *m = (int *) map + 1; 225 signed char *p, *q; 226 227 for (; m < end; m++) { 228 if (*m == INT_CONF) { p = (signed char *) m ; goto conf; } 229 if (*m == INT_ONFI) { p = (signed char *) m-1; goto conf; } 230 if (*m == INT_NFIG) { p = (signed char *) m-2; goto conf; } 231 if (*m == INT_FIG_) { p = (signed char *) m-3; goto conf; } 232 continue; 233 conf: 234 if (p > map + len - 7) 235 continue; 236 if (memcmp(p, "CONFIG_", 7)) 237 continue; 238 for (q = p + 7; q < map + len; q++) { 239 if (!(isalnum(*q) || *q == '_')) 240 goto found; 241 } 242 continue; 243 244 found: 245 use_config(p+7, q-p-7); 246 } 247 } 248 249 /* test is s ends in sub */ 250 int strrcmp(char *s, char *sub) 251 { 252 int slen = strlen(s); 253 int sublen = strlen(sub); 254 255 if (sublen > slen) 256 return 1; 257 258 return memcmp(s + slen - sublen, sub, sublen); 259 } 260 261 void do_config_file(char *filename) 262 { 263 struct stat st; 264 int fd; 265 void *map; 266 267 fd = open(filename, O_RDONLY); 268 if (fd < 0) { 269 fprintf(stderr, "fixdep: "); 270 perror(filename); 271 exit(2); 272 } 273 fstat(fd, &st); 274 if (st.st_size == 0) { 275 close(fd); 276 return; 277 } 278 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 279 if ((long) map == -1) { 280 perror("fixdep: mmap"); 281 close(fd); 282 return; 283 } 284 285 parse_config_file(map, st.st_size); 286 287 munmap(map, st.st_size); 288 289 close(fd); 290 } 291 292 void parse_dep_file(void *map, size_t len) 293 { 294 signed char *m = map; 295 signed char *end = m + len; 296 signed char *p; 297 char s[PATH_MAX]; 298 299 p = strchr(m, ':'); 300 if (!p) { 301 fprintf(stderr, "fixdep: parse error\n"); 302 exit(1); 303 } 304 memcpy(s, m, p-m); s[p-m] = 0; 305 printf("deps_%s := \\\n", target); 306 m = p+1; 307 308 clear_config(); 309 310 while (m < end) { 311 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) 312 m++; 313 p = m; 314 while (p < end && *p != ' ') p++; 315 if (p == end) { 316 do p--; while (!isalnum(*p)); 317 p++; 318 } 319 memcpy(s, m, p-m); s[p-m] = 0; 320 if (strrcmp(s, "include/linux/autoconf.h") && 321 strrcmp(s, "arch/um/include/uml-config.h") && 322 strrcmp(s, ".ver")) { 323 printf(" %s \\\n", s); 324 do_config_file(s); 325 } 326 m = p + 1; 327 } 328 printf("\n%s: $(deps_%s)\n\n", target, target); 329 printf("$(deps_%s):\n", target); 330 } 331 332 void print_deps(void) 333 { 334 struct stat st; 335 int fd; 336 void *map; 337 338 fd = open(depfile, O_RDONLY); 339 if (fd < 0) { 340 fprintf(stderr, "fixdep: "); 341 perror(depfile); 342 exit(2); 343 } 344 fstat(fd, &st); 345 if (st.st_size == 0) { 346 fprintf(stderr,"fixdep: %s is empty\n",depfile); 347 close(fd); 348 return; 349 } 350 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 351 if ((long) map == -1) { 352 perror("fixdep: mmap"); 353 close(fd); 354 return; 355 } 356 357 parse_dep_file(map, st.st_size); 358 359 munmap(map, st.st_size); 360 361 close(fd); 362 } 363 364 void traps(void) 365 { 366 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF"; 367 368 if (*(int *)test != INT_CONF) { 369 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n", 370 *(int *)test); 371 exit(2); 372 } 373 } 374 375 int main(int argc, char *argv[]) 376 { 377 traps(); 378 379 if (argc != 4) 380 usage(); 381 382 depfile = argv[1]; 383 target = argv[2]; 384 cmdline = argv[3]; 385 386 print_cmdline(); 387 print_deps(); 388 389 return 0; 390 } 391