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 * kconfig populates a tree in include/config/ with an empty file
32 * for each config symbol and when the configuration is updated
33 * the files representing changed config options are touched
34 * which then let make pick up the changes and the files that use
35 * the config symbols are rebuilt.
36 *
37 * So if the user changes his CONFIG_HIS_DRIVER option, only the objects
38 * which depend on "include/linux/config/his/driver.h" will be rebuilt,
39 * so most likely only his driver ;-)
40 *
41 * The idea above dates, by the way, back to Michael E Chastain, AFAIK.
42 *
43 * So to get dependencies right, there are two issues:
44 * o if any of the files the compiler read changed, we need to rebuild
45 * o if the command line given to the compile the file changed, we
46 * better rebuild as well.
47 *
48 * The former is handled by using the -MD output, the later by saving
49 * the command line used to compile the old object and comparing it
50 * to the one we would now use.
51 *
52 * Again, also this idea is pretty old and has been discussed on
53 * kbuild-devel a long time ago. I don't have a sensibly working
54 * internet connection right now, so I rather don't mention names
55 * without double checking.
56 *
57 * This code here has been based partially based on mkdep.c, which
58 * says the following about its history:
59 *
60 * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>.
61 * This is a C version of syncdep.pl by Werner Almesberger.
62 *
63 *
64 * It is invoked as
65 *
66 * fixdep <depfile> <target> <cmdline>
67 *
68 * and will read the dependency file <depfile>
69 *
70 * The transformed dependency snipped is written to stdout.
71 *
72 * It first generates a line
73 *
74 * cmd_<target> = <cmdline>
75 *
76 * and then basically copies the .<target>.d file to stdout, in the
77 * process filtering out the dependency on linux/autoconf.h and adding
78 * dependencies on include/config/my/option.h for every
79 * CONFIG_MY_OPTION encountered in any of the prequisites.
80 *
81 * It will also filter out all the dependencies on *.ver. We need
82 * to make sure that the generated version checksum are globally up
83 * to date before even starting the recursive build, so it's too late
84 * at this point anyway.
85 *
86 * The algorithm to grep for "CONFIG_..." is bit unusual, but should
87 * be fast ;-) We don't even try to really parse the header files, but
88 * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will
89 * be picked up as well. It's not a problem with respect to
90 * correctness, since that can only give too many dependencies, thus
91 * we cannot miss a rebuild. Since people tend to not mention totally
92 * unrelated CONFIG_ options all over the place, it's not an
93 * efficiency problem either.
94 *
95 * (Note: it'd be easy to port over the complete mkdep state machine,
96 * but I don't think the added complexity is worth it)
97 */
98 /*
99 * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto
100 * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not
101 * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as
102 * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h,
103 * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that
104 * those files will have correct dependencies.
105 */
106
107 #include <sys/types.h>
108 #include <sys/stat.h>
109 #include <sys/mman.h>
110 #include <unistd.h>
111 #include <fcntl.h>
112 #include <string.h>
113 #include <stdlib.h>
114 #include <stdio.h>
115 #include <limits.h>
116 #include <ctype.h>
117 #include <arpa/inet.h>
118
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 char *target;
125 char *depfile;
126 char *cmdline;
127
128 void usage(void)
129
130 {
131 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
132 exit(1);
133 }
134
135 /*
136 * Print out the commandline prefixed with cmd_<target filename> :=
137 */
138 void print_cmdline(void)
139 {
140 printf("cmd_%s := %s\n\n", target, cmdline);
141 }
142
143 char * str_config = NULL;
144 int size_config = 0;
145 int len_config = 0;
146
147 /*
148 * Grow the configuration string to a desired length.
149 * Usually the first growth is plenty.
150 */
151 void grow_config(int len)
152 {
153 while (len_config + len > size_config) {
154 if (size_config == 0)
155 size_config = 2048;
156 str_config = realloc(str_config, size_config *= 2);
157 if (str_config == NULL)
158 { perror("fixdep:malloc"); exit(1); }
159 }
160 }
161
162
163
164 /*
165 * Lookup a value in the configuration string.
166 */
167 int is_defined_config(const char * name, int len)
168 {
169 const char * pconfig;
170 const char * plast = str_config + len_config - len;
171 for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) {
172 if (pconfig[ -1] == '\n'
173 && pconfig[len] == '\n'
174 && !memcmp(pconfig, name, len))
175 return 1;
176 }
177 return 0;
178 }
179
180 /*
181 * Add a new value to the configuration string.
182 */
183 void define_config(const char * name, int len)
184 {
185 grow_config(len + 1);
186
187 memcpy(str_config+len_config, name, len);
188 len_config += len;
189 str_config[len_config++] = '\n';
190 }
191
192 /*
193 * Clear the set of configuration strings.
194 */
195 void clear_config(void)
196 {
197 len_config = 0;
198 define_config("", 0);
199 }
200
201 /*
202 * Record the use of a CONFIG_* word.
203 */
204 void use_config(char *m, int slen)
205 {
206 char s[PATH_MAX];
207 char *p;
208
209 if (is_defined_config(m, slen))
210 return;
211
212 define_config(m, slen);
213
214 memcpy(s, m, slen); s[slen] = 0;
215
216 for (p = s; p < s + slen; p++) {
217 if (*p == '_')
218 *p = '/';
219 else
220 *p = tolower((int)*p);
221 }
222 printf(" $(wildcard include/config/%s.h) \\\n", s);
223 }
224
225 void parse_config_file(char *map, size_t len)
226 {
227 int *end = (int *) (map + len);
228 /* start at +1, so that p can never be < map */
229 int *m = (int *) map + 1;
230 char *p, *q;
231
232 for (; m < end; m++) {
233 if (*m == INT_CONF) { p = (char *) m ; goto conf; }
234 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; }
235 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; }
236 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; }
237 continue;
238 conf:
239 if (p > map + len - 7)
240 continue;
241 if (memcmp(p, "CONFIG_", 7))
242 continue;
243 for (q = p + 7; q < map + len; q++) {
244 if (!(isalnum(*q) || *q == '_'))
245 goto found;
246 }
247 continue;
248
249 found:
250 if (!memcmp(q - 7, "_MODULE", 7))
251 q -= 7;
252 if( (q-p-7) < 0 )
253 continue;
254 use_config(p+7, q-p-7);
255 }
256 }
257
258 /* test is s ends in sub */
259 int strrcmp(char *s, char *sub)
260 {
261 int slen = strlen(s);
262 int sublen = strlen(sub);
263
264 if (sublen > slen)
265 return 1;
266
267 return memcmp(s + slen - sublen, sub, sublen);
268 }
269
270 void do_config_file(char *filename)
271 {
272 struct stat st;
273 int fd;
274 void *map;
275
276 fd = open(filename, O_RDONLY);
277 if (fd < 0) {
278 fprintf(stderr, "fixdep: ");
279 perror(filename);
280 exit(2);
281 }
282 fstat(fd, &st);
283 if (st.st_size == 0) {
284 close(fd);
285 return;
286 }
287 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
288 if ((long) map == -1) {
289 perror("fixdep: mmap");
290 close(fd);
291 return;
292 }
293
294 parse_config_file(map, st.st_size);
295
296 munmap(map, st.st_size);
297
298 close(fd);
299 }
300
301 void parse_dep_file(void *map, size_t len)
302 {
303 char *m = map;
304 char *end = m + len;
305 char *p;
306 char s[PATH_MAX];
307
308 p = strchr(m, ':');
309 if (!p) {
310 fprintf(stderr, "fixdep: parse error\n");
311 exit(1);
312 }
313 memcpy(s, m, p-m); s[p-m] = 0;
314 printf("deps_%s := \\\n", target);
315 m = p+1;
316
317 clear_config();
318
319 while (m < end) {
320 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
321 m++;
322 p = m;
323 while (p < end && *p != ' ') p++;
324 if (p == end) {
325 do p--; while (!isalnum(*p));
326 p++;
327 }
328 memcpy(s, m, p-m); s[p-m] = 0;
329 if (strrcmp(s, "include/linux/autoconf.h") &&
330 strrcmp(s, "arch/um/include/uml-config.h") &&
331 strrcmp(s, ".ver")) {
332 printf(" %s \\\n", s);
333 do_config_file(s);
334 }
335 m = p + 1;
336 }
337 printf("\n%s: $(deps_%s)\n\n", target, target);
338 printf("$(deps_%s):\n", target);
339 }
340
341 void print_deps(void)
342 {
343 struct stat st;
344 int fd;
345 void *map;
346
347 fd = open(depfile, O_RDONLY);
348 if (fd < 0) {
349 fprintf(stderr, "fixdep: ");
350 perror(depfile);
351 exit(2);
352 }
353 fstat(fd, &st);
354 if (st.st_size == 0) {
355 fprintf(stderr,"fixdep: %s is empty\n",depfile);
356 close(fd);
357 return;
358 }
359 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
360 if ((long) map == -1) {
361 perror("fixdep: mmap");
362 close(fd);
363 return;
364 }
365
366 parse_dep_file(map, st.st_size);
367
368 munmap(map, st.st_size);
369
370 close(fd);
371 }
372
373 void traps(void)
374 {
375 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
376 int *p = (int *)test;
377
378 if (*p != INT_CONF) {
379 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n",
380 *p);
381 exit(2);
382 }
383 }
384
385 int main(int argc, char *argv[])
386 {
387 traps();
388
389 if (argc != 4)
390 usage();
391
392 depfile = argv[1];
393 target = argv[2];
394 cmdline = argv[3];
395
396 print_cmdline();
397 print_deps();
398
399 return 0;
400 }
401
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