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 autoconf.h. 20 * 21 * If the user re-runs make *config, autoconf.h will be 22 * regenerated. make notices that and will rebuild every file which 23 * includes autoconf.h, i.e. basically all files. This is extremely 24 * annoying if the user just changed CONFIG_HIS_DRIVER from n to m. 25 * 26 * So we play the same trick that "mkdep" played before. We replace 27 * the dependency on autoconf.h by a dependency on every config 28 * option which is mentioned in any of the listed prequisites. 29 * 30 * kconfig populates a tree in include/config/ with an empty file 31 * for each config symbol and when the configuration is updated 32 * the files representing changed config options are touched 33 * which then let make pick up the changes and the files that use 34 * the config symbols are rebuilt. 35 * 36 * So if the user changes his CONFIG_HIS_DRIVER option, only the objects 37 * which depend on "include/linux/config/his/driver.h" will be rebuilt, 38 * so most likely only his driver ;-) 39 * 40 * The idea above dates, by the way, back to Michael E Chastain, AFAIK. 41 * 42 * So to get dependencies right, there are two issues: 43 * o if any of the files the compiler read changed, we need to rebuild 44 * o if the command line given to the compile the file changed, we 45 * better rebuild as well. 46 * 47 * The former is handled by using the -MD output, the later by saving 48 * the command line used to compile the old object and comparing it 49 * to the one we would now use. 50 * 51 * Again, also this idea is pretty old and has been discussed on 52 * kbuild-devel a long time ago. I don't have a sensibly working 53 * internet connection right now, so I rather don't mention names 54 * without double checking. 55 * 56 * This code here has been based partially based on mkdep.c, which 57 * says the following about its history: 58 * 59 * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>. 60 * This is a C version of syncdep.pl by Werner Almesberger. 61 * 62 * 63 * It is invoked as 64 * 65 * fixdep <depfile> <target> <cmdline> 66 * 67 * and will read the dependency file <depfile> 68 * 69 * The transformed dependency snipped is written to stdout. 70 * 71 * It first generates a line 72 * 73 * cmd_<target> = <cmdline> 74 * 75 * and then basically copies the .<target>.d file to stdout, in the 76 * process filtering out the dependency on autoconf.h and adding 77 * dependencies on include/config/my/option.h for every 78 * CONFIG_MY_OPTION encountered in any of the prequisites. 79 * 80 * It will also filter out all the dependencies on *.ver. We need 81 * to make sure that the generated version checksum are globally up 82 * to date before even starting the recursive build, so it's too late 83 * at this point anyway. 84 * 85 * The algorithm to grep for "CONFIG_..." is bit unusual, but should 86 * be fast ;-) We don't even try to really parse the header files, but 87 * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will 88 * be picked up as well. It's not a problem with respect to 89 * correctness, since that can only give too many dependencies, thus 90 * we cannot miss a rebuild. Since people tend to not mention totally 91 * unrelated CONFIG_ options all over the place, it's not an 92 * efficiency problem either. 93 * 94 * (Note: it'd be easy to port over the complete mkdep state machine, 95 * but I don't think the added complexity is worth it) 96 */ 97/* 98 * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto 99 * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not 100 * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as 101 * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h, 102 * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that 103 * those files will have correct dependencies. 104 */ 105 106#include <sys/types.h> 107#include <sys/stat.h> 108#include <sys/mman.h> 109#include <unistd.h> 110#include <fcntl.h> 111#include <string.h> 112#include <stdlib.h> 113#include <stdio.h> 114#include <limits.h> 115#include <ctype.h> 116#include <arpa/inet.h> 117 118#define INT_CONF ntohl(0x434f4e46) 119#define INT_ONFI ntohl(0x4f4e4649) 120#define INT_NFIG ntohl(0x4e464947) 121#define INT_FIG_ ntohl(0x4649475f) 122 123char *target; 124char *depfile; 125char *cmdline; 126 127static void usage(void) 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 */ 136static void print_cmdline(void) 137{ 138 printf("cmd_%s := %s\n\n", target, cmdline); 139} 140 141char * str_config = NULL; 142int size_config = 0; 143int len_config = 0; 144 145/* 146 * Grow the configuration string to a desired length. 147 * Usually the first growth is plenty. 148 */ 149static 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 */ 165static 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 */ 181static 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 */ 193static 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 */ 202static 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 223static 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 if (!memcmp(q - 7, "_MODULE", 7)) 249 q -= 7; 250 if( (q-p-7) < 0 ) 251 continue; 252 use_config(p+7, q-p-7); 253 } 254} 255 256/* test is s ends in sub */ 257static int strrcmp(char *s, char *sub) 258{ 259 int slen = strlen(s); 260 int sublen = strlen(sub); 261 262 if (sublen > slen) 263 return 1; 264 265 return memcmp(s + slen - sublen, sub, sublen); 266} 267 268static void do_config_file(char *filename) 269{ 270 struct stat st; 271 int fd; 272 void *map; 273 274 fd = open(filename, O_RDONLY); 275 if (fd < 0) { 276 fprintf(stderr, "fixdep: "); 277 perror(filename); 278 exit(2); 279 } 280 fstat(fd, &st); 281 if (st.st_size == 0) { 282 close(fd); 283 return; 284 } 285 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 286 if ((long) map == -1) { 287 perror("fixdep: mmap"); 288 close(fd); 289 return; 290 } 291 292 parse_config_file(map, st.st_size); 293 294 munmap(map, st.st_size); 295 296 close(fd); 297} 298 299static void parse_dep_file(void *map, size_t len) 300{ 301 char *m = map; 302 char *end = m + len; 303 char *p; 304 char s[PATH_MAX]; 305 306 p = strchr(m, ':'); 307 if (!p) { 308 fprintf(stderr, "fixdep: parse error\n"); 309 exit(1); 310 } 311 memcpy(s, m, p-m); s[p-m] = 0; 312 printf("deps_%s := \\\n", target); 313 m = p+1; 314 315 clear_config(); 316 317 while (m < end) { 318 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) 319 m++; 320 p = m; 321 while (p < end && *p != ' ') p++; 322 if (p == end) { 323 do p--; while (!isalnum(*p)); 324 p++; 325 } 326 memcpy(s, m, p-m); s[p-m] = 0; 327 if (strrcmp(s, "include/generated/autoconf.h") && 328 strrcmp(s, "arch/um/include/uml-config.h") && 329 strrcmp(s, ".ver")) { 330 printf(" %s \\\n", s); 331 do_config_file(s); 332 } 333 m = p + 1; 334 } 335 printf("\n%s: $(deps_%s)\n\n", target, target); 336 printf("$(deps_%s):\n", target); 337} 338 339static void print_deps(void) 340{ 341 struct stat st; 342 int fd; 343 void *map; 344 345 fd = open(depfile, O_RDONLY); 346 if (fd < 0) { 347 fprintf(stderr, "fixdep: "); 348 perror(depfile); 349 exit(2); 350 } 351 fstat(fd, &st); 352 if (st.st_size == 0) { 353 fprintf(stderr,"fixdep: %s is empty\n",depfile); 354 close(fd); 355 return; 356 } 357 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 358 if ((long) map == -1) { 359 perror("fixdep: mmap"); 360 close(fd); 361 return; 362 } 363 364 parse_dep_file(map, st.st_size); 365 366 munmap(map, st.st_size); 367 368 close(fd); 369} 370 371static void traps(void) 372{ 373 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF"; 374 int *p = (int *)test; 375 376 if (*p != INT_CONF) { 377 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n", 378 *p); 379 exit(2); 380 } 381} 382 383int main(int argc, char *argv[]) 384{ 385 traps(); 386 387 if (argc != 4) 388 usage(); 389 390 depfile = argv[1]; 391 target = argv[2]; 392 cmdline = argv[3]; 393 394 print_cmdline(); 395 print_deps(); 396 397 return 0; 398} 399