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 //bbox disabled: #include <alloca.h>
117
118 /* bbox: not needed
119 #define INT_CONF ntohl(0x434f4e46)
120 #define INT_ONFI ntohl(0x4f4e4649)
121 #define INT_NFIG ntohl(0x4e464947)
122 #define INT_FIG_ ntohl(0x4649475f)
123 */
124
125 char *target;
126 char *depfile;
127 char *cmdline;
128
usage(void)129 void usage(void)
130
131 {
132 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
133 exit(1);
134 }
135
136 /*
137 * Print out the commandline prefixed with cmd_<target filename> :=
138 */
print_cmdline(void)139 void print_cmdline(void)
140 {
141 printf("cmd_%s := %s\n\n", target, cmdline);
142 }
143
144 char * str_config = NULL;
145 int size_config = 0;
146 int len_config = 0;
147
148 /*
149 * Grow the configuration string to a desired length.
150 * Usually the first growth is plenty.
151 */
grow_config(int len)152 void grow_config(int len)
153 {
154 while (len_config + len > size_config) {
155 if (size_config == 0)
156 size_config = 2048;
157 str_config = realloc(str_config, size_config *= 2);
158 if (str_config == NULL)
159 { perror("fixdep:malloc"); exit(1); }
160 }
161 }
162
163
164
165 /*
166 * Lookup a value in the configuration string.
167 */
is_defined_config(const char * name,int len)168 int is_defined_config(const char * name, int len)
169 {
170 const char * pconfig;
171 const char * plast = str_config + len_config - len;
172 for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) {
173 if (pconfig[ -1] == '\n'
174 && pconfig[len] == '\n'
175 && !memcmp(pconfig, name, len))
176 return 1;
177 }
178 return 0;
179 }
180
181 /*
182 * Add a new value to the configuration string.
183 */
define_config(const char * name,int len)184 void define_config(const char * name, int len)
185 {
186 grow_config(len + 1);
187
188 memcpy(str_config+len_config, name, len);
189 len_config += len;
190 str_config[len_config++] = '\n';
191 }
192
193 /*
194 * Clear the set of configuration strings.
195 */
clear_config(void)196 void clear_config(void)
197 {
198 len_config = 0;
199 define_config("", 0);
200 }
201
202 /*
203 * Record the use of a CONFIG_* word.
204 */
use_config(char * m,int slen)205 void use_config(char *m, int slen)
206 {
207 char *s = alloca(slen+1);
208 char *p;
209
210 if (is_defined_config(m, slen))
211 return;
212
213 define_config(m, slen);
214
215 memcpy(s, m, slen); s[slen] = 0;
216
217 for (p = s; p < s + slen; p++) {
218 if (*p == '_')
219 *p = '/';
220 else
221 *p = tolower((int)*p);
222 }
223 printf(" $(wildcard include/config/%s.h) \\\n", s);
224 }
225
parse_config_file(char * map,size_t len)226 void parse_config_file(char *map, size_t len)
227 {
228 /* modified for bbox */
229 unsigned char *end_3 = (unsigned char *)map + len - 3; /* 3 == length of "IF_" */
230 unsigned char *end_7 = (unsigned char *)map + len - 7;
231 unsigned char *p = (unsigned char *)map;
232 unsigned char *q;
233 int off;
234
235 for (; p <= end_3; p++) {
236 /* Find next identifier's beginning */
237 if (!(isalnum(*p) || *p == '_'))
238 continue;
239
240 /* Check it */
241 if (p < end_7 && p[6] == '_') {
242 if (!memcmp(p, "CONFIG", 6)) goto conf7;
243 if (!memcmp(p, "ENABLE", 6)) goto conf7;
244 if (!memcmp(p, "IF_NOT", 6)) goto conf7;
245 }
246 /* we have at least 3 chars because of p <= end_3 */
247 /*if (!memcmp(p, "IF_", 3)) ...*/
248 if (p[0] == 'I' && p[1] == 'F' && p[2] == '_') {
249 off = 3;
250 goto conf;
251 }
252
253 /* This identifier is not interesting, skip it */
254 while (p <= end_3 && (isalnum(*p) || *p == '_'))
255 p++;
256 continue;
257
258 conf7: off = 7;
259 conf:
260 p += off;
261 for (q = p; q < end_3+3; q++) {
262 if (!(isalnum(*q) || *q == '_'))
263 break;
264 }
265 if (q != p) {
266 use_config((char*)p, q - p);
267 }
268 }
269 }
270
271 /* test is s ends in sub */
strrcmp(char * s,char * sub)272 int strrcmp(char *s, char *sub)
273 {
274 int slen = strlen(s);
275 int sublen = strlen(sub);
276
277 if (sublen > slen)
278 return 1;
279
280 return memcmp(s + slen - sublen, sub, sublen);
281 }
282
do_config_file(char * filename)283 void do_config_file(char *filename)
284 {
285 struct stat st;
286 int fd;
287 void *map;
288
289 fd = open(filename, O_RDONLY);
290 if (fd < 0) {
291 fprintf(stderr, "fixdep: ");
292 perror(filename);
293 exit(2);
294 }
295 fstat(fd, &st);
296 if (st.st_size == 0) {
297 close(fd);
298 return;
299 }
300 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
301 if ((long) map == -1) {
302 perror("fixdep: mmap");
303 close(fd);
304 return;
305 }
306
307 parse_config_file(map, st.st_size);
308
309 munmap(map, st.st_size);
310
311 close(fd);
312 }
313
parse_dep_file(void * map,size_t len)314 void parse_dep_file(void *map, size_t len)
315 {
316 char *m = map;
317 char *end = m + len;
318 char *p;
319 char *s = alloca(len);
320
321 p = memchr(m, ':', len);
322 if (!p) {
323 fprintf(stderr, "fixdep: parse error\n");
324 exit(1);
325 }
326 memcpy(s, m, p-m); s[p-m] = 0;
327 printf("deps_%s := \\\n", target);
328 m = p+1;
329
330 clear_config();
331
332 while (m < end) {
333 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n' || *m == '\r'))
334 m++;
335 p = m;
336 while (p < end && *p != ' ') p++;
337 if (p == end) {
338 do p--; while (!isalnum((unsigned char)*p));
339 p++;
340 }
341 memcpy(s, m, p-m); s[p-m] = 0;
342 if (strrcmp(s, "include/autoconf.h") &&
343 strrcmp(s, "arch/um/include/uml-config.h") &&
344 strrcmp(s, ".ver")) {
345 printf(" %s \\\n", s);
346 do_config_file(s);
347 }
348 m = p + 1;
349 }
350 printf("\n%s: $(deps_%s)\n\n", target, target);
351 printf("$(deps_%s):\n", target);
352 }
353
print_deps(void)354 void print_deps(void)
355 {
356 struct stat st;
357 int fd;
358 void *map;
359
360 fd = open(depfile, O_RDONLY);
361 if (fd < 0) {
362 fprintf(stderr, "fixdep: ");
363 perror(depfile);
364 exit(2);
365 }
366 fstat(fd, &st);
367 if (st.st_size == 0) {
368 fprintf(stderr,"fixdep: %s is empty\n",depfile);
369 close(fd);
370 return;
371 }
372 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
373 if ((long) map == -1) {
374 perror("fixdep: mmap");
375 close(fd);
376 return;
377 }
378
379 parse_dep_file(map, st.st_size);
380
381 munmap(map, st.st_size);
382
383 close(fd);
384 }
385
traps(void)386 void traps(void)
387 {
388 /* bbox: not needed
389 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
390
391 if (*(int *)test != INT_CONF) {
392 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n",
393 *(int *)test);
394 exit(2);
395 }
396 */
397 }
398
main(int argc,char ** argv)399 int main(int argc, char **argv)
400 {
401 traps();
402
403 if (argc != 4)
404 usage();
405
406 depfile = argv[1];
407 target = argv[2];
408 cmdline = argv[3];
409
410 print_cmdline();
411 print_deps();
412
413 return 0;
414 }
415