scripts/fixdep.c

   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 autconf.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 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/autconf.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 #include <sys/types.h>
  98 #include <sys/stat.h>
  99 #include <sys/mman.h>
 100 #include <unistd.h>
 101 #include <fcntl.h>
 102 #include <string.h>
 103 #include <stdlib.h>
 104 #include <stdio.h>
 105 #include <limits.h>
 106 #include <ctype.h>
 107 #include <netinet/in.h>
 108
 109 #define INT_CONF ntohl(0x434f4e46)
 110 #define INT_ONFI ntohl(0x4f4e4649)
 111 #define INT_NFIG ntohl(0x4e464947)
 112 #define INT_FIG_ ntohl(0x4649475f)
 113
 114 char *target;
 115 char *depfile;
 116 char *cmdline;
 117
 118 void usage(void)
 119
 120 {
 121         fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
 122         exit(1);
 123 }
 124
 125 void print_cmdline(void)
 126 {
 127         printf("cmd_%s := %s\n\n", target, cmdline);
 128 }
 129
 130 char * str_config  = NULL;
 131 int    size_config = 0;
 132 int    len_config  = 0;
 133
 134 /*
 135  * Grow the configuration string to a desired length.
 136  * Usually the first growth is plenty.
 137  */
 138 void grow_config(int len)
 139 {
 140         while (len_config + len > size_config) {
 141                 if (size_config == 0)
 142                         size_config = 2048;
 143                 str_config = realloc(str_config, size_config *= 2);
 144                 if (str_config == NULL)
 145                         { perror("fixdep:malloc"); exit(1); }
 146         }
 147 }
 148
 149
 150
 151 /*
 152  * Lookup a value in the configuration string.
 153  */
 154 int is_defined_config(const char * name, int len)
 155 {
 156         const char * pconfig;
 157         const char * plast = str_config + len_config - len;
 158         for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) {
 159                 if (pconfig[ -1] == '\n'
 160                 &&  pconfig[len] == '\n'
 161                 &&  !memcmp(pconfig, name, len))
 162                         return 1;
 163         }
 164         return 0;
 165 }
 166
 167 /*
 168  * Add a new value to the configuration string.
 169  */
 170 void define_config(const char * name, int len)
 171 {
 172         grow_config(len + 1);
 173
 174         memcpy(str_config+len_config, name, len);
 175         len_config += len;
 176         str_config[len_config++] = '\n';
 177 }
 178
 179 /*
 180  * Clear the set of configuration strings.
 181  */
 182 void clear_config(void)
 183 {
 184         len_config = 0;
 185         define_config("", 0);
 186 }
 187
 188 /*
 189  * Record the use of a CONFIG_* word.
 190  */
 191 void use_config(char *m, int slen)
 192 {
 193         char s[PATH_MAX];
 194         char *p;
 195
 196         if (is_defined_config(m, slen))
 197             return;
 198
 199         define_config(m, slen);
 200
 201         memcpy(s, m, slen); s[slen] = 0;
 202
 203         for (p = s; p < s + slen; p++) {
 204                 if (*p == '_')
 205                         *p = '/';
 206                 else
 207                         *p = tolower((unsigned char)*p);
 208         }
 209         printf("    $(wildcard include/config/%s.h) \\\n", s);
 210 }
 211
 212 void parse_config_file(char *map, size_t len)
 213 {
 214         int *end = (int *) (map + len);
 215         /* start at +1, so that p can never be < map */
 216         int *m   = (int *) map + 1;
 217         char *p, *q;
 218
 219         for (; m < end; m++) {
 220                 if (*m == INT_CONF) { p = (char *) m  ; goto conf; }
 221                 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; }
 222                 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; }
 223                 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; }
 224                 continue;
 225         conf:
 226                 if (p > map + len - 7)
 227                         continue;
 228                 if (memcmp(p, "CONFIG_", 7))
 229                         continue;
 230                 for (q = p + 7; q < map + len; q++) {
 231                         if (!(isalnum(*q) || *q == '_'))
 232                                 goto found;
 233                 }
 234                 continue;
 235
 236         found:
 237                 use_config(p+7, q-p-7);
 238         }
 239 }
 240
 241 /* test is s ends in sub */
 242 int strrcmp(char *s, char *sub)
 243 {
 244         int slen = strlen(s);
 245         int sublen = strlen(sub);
 246
 247         if (sublen > slen)
 248                 return 1;
 249
 250         return memcmp(s + slen - sublen, sub, sublen);
 251 }
 252
 253 void do_config_file(char *filename)
 254 {
 255         struct stat st;
 256         int fd;
 257         void *map;
 258
 259         fd = open(filename, O_RDONLY);
 260         if (fd < 0) {
 261                 fprintf(stderr, "fixdep: ");
 262                 perror(filename);
 263                 exit(2);
 264         }
 265         fstat(fd, &st);
 266         if (st.st_size == 0) {
 267                 close(fd);
 268                 return;
 269         }
 270         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 271         if ((long) map == -1) {
 272                 perror("fixdep: mmap");
 273                 close(fd);
 274                 return;
 275         }
 276
 277         parse_config_file(map, st.st_size);
 278
 279         munmap(map, st.st_size);
 280
 281         close(fd);
 282 }
 283
 284 void parse_dep_file(void *map, size_t len)
 285 {
 286         char *m = map;
 287         char *end = m + len;
 288         char *p;
 289         char s[PATH_MAX];
 290
 291         p = strchr(m, ':');
 292         if (!p) {
 293                 fprintf(stderr, "fixdep: parse error\n");
 294                 exit(1);
 295         }
 296         memcpy(s, m, p-m); s[p-m] = 0;
 297         printf("deps_%s := \\\n", target);
 298         m = p+1;
 299
 300         clear_config();
 301
 302         while (m < end) {
 303                 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
 304                         m++;
 305                 p = m;
 306                 while (p < end && *p != ' ') p++;
 307                 if (p == end) {
 308                         do p--; while (!isalnum(*p));
 309                         p++;
 310                 }
 311                 memcpy(s, m, p-m); s[p-m] = 0;
 312                 if (strrcmp(s, "include/linux/autoconf.h") &&
 313                     strrcmp(s, ".ver")) {
 314                         printf("  %s \\\n", s);
 315                         do_config_file(s);
 316                 }
 317                 m = p + 1;
 318         }
 319         printf("\n%s: $(deps_%s)\n\n", target, target);
 320         printf("$(deps_%s):\n", target);
 321 }
 322
 323 void print_deps(void)
 324 {
 325         struct stat st;
 326         int fd;
 327         void *map;
 328
 329         fd = open(depfile, O_RDONLY);
 330         if (fd < 0) {
 331                 fprintf(stderr, "fixdep: ");
 332                 perror(depfile);
 333                 exit(2);
 334         }
 335         fstat(fd, &st);
 336         if (st.st_size == 0) {
 337                 fprintf(stderr,"fixdep: %s is empty\n",depfile);
 338                 close(fd);
 339                 return;
 340         }
 341         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 342         if ((long) map == -1) {
 343                 perror("fixdep: mmap");
 344                 close(fd);
 345                 return;
 346         }
 347
 348         parse_dep_file(map, st.st_size);
 349
 350         munmap(map, st.st_size);
 351
 352         close(fd);
 353 }
 354
 355 void traps(void)
 356 {
 357         static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
 358
 359         if (*(int *)test != INT_CONF) {
 360                 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n",
 361                         *(int *)test);
 362                 exit(2);
 363         }
 364 }
 365
 366 int main(int argc, char *argv[])
 367 {
 368         traps();
 369
 370         if (argc != 4)
 371                 usage();
 372
 373         depfile = argv[1];
 374         target = argv[2];
 375         cmdline = argv[3];
 376
 377         print_cmdline();
 378         print_deps();
 379
 380         return 0;
 381 }