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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
122char *target;
123char *depfile;
124char *cmdline;
125
126void usage(void)
127
128{
129 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
130 exit(1);
131}
132
Sam Ravnborg4d99f932005-12-25 23:21:14 +0100133/*
134 * Print out the commandline prefixed with cmd_<target filename> :=
Jan Beulich6176aa92006-01-30 10:04:27 +0100135 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136void print_cmdline(void)
137{
Jan Beulich6176aa92006-01-30 10:04:27 +0100138 printf("cmd_%s := %s\n\n", target, cmdline);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139}
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 */
149void 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 */
165int 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 */
181void 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 */
193void clear_config(void)
194{
195 len_config = 0;
196 define_config("", 0);
197}
198
199/*
200 * Record the use of a CONFIG_* word.
201 */
202void 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
J.A. Magallon48b9d032005-06-25 14:59:22 -0700218 *p = tolower((int)*p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 }
220 printf(" $(wildcard include/config/%s.h) \\\n", s);
221}
222
J.A. Magallon48b9d032005-06-25 14:59:22 -0700223void parse_config_file(char *map, size_t len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224{
225 int *end = (int *) (map + len);
226 /* start at +1, so that p can never be < map */
227 int *m = (int *) map + 1;
J.A. Magallon48b9d032005-06-25 14:59:22 -0700228 char *p, *q;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229
230 for (; m < end; m++) {
J.A. Magallon48b9d032005-06-25 14:59:22 -0700231 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; }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 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 use_config(p+7, q-p-7);
249 }
250}
251
252/* test is s ends in sub */
253int strrcmp(char *s, char *sub)
254{
255 int slen = strlen(s);
256 int sublen = strlen(sub);
257
258 if (sublen > slen)
259 return 1;
260
261 return memcmp(s + slen - sublen, sub, sublen);
262}
263
264void do_config_file(char *filename)
265{
266 struct stat st;
267 int fd;
268 void *map;
269
270 fd = open(filename, O_RDONLY);
271 if (fd < 0) {
272 fprintf(stderr, "fixdep: ");
273 perror(filename);
274 exit(2);
275 }
276 fstat(fd, &st);
277 if (st.st_size == 0) {
278 close(fd);
279 return;
280 }
281 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
282 if ((long) map == -1) {
283 perror("fixdep: mmap");
284 close(fd);
285 return;
286 }
287
288 parse_config_file(map, st.st_size);
289
290 munmap(map, st.st_size);
291
292 close(fd);
293}
294
295void parse_dep_file(void *map, size_t len)
296{
J.A. Magallon48b9d032005-06-25 14:59:22 -0700297 char *m = map;
298 char *end = m + len;
299 char *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 char s[PATH_MAX];
301
302 p = strchr(m, ':');
303 if (!p) {
304 fprintf(stderr, "fixdep: parse error\n");
305 exit(1);
306 }
307 memcpy(s, m, p-m); s[p-m] = 0;
308 printf("deps_%s := \\\n", target);
309 m = p+1;
310
311 clear_config();
312
313 while (m < end) {
314 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
315 m++;
316 p = m;
317 while (p < end && *p != ' ') p++;
318 if (p == end) {
319 do p--; while (!isalnum(*p));
320 p++;
321 }
322 memcpy(s, m, p-m); s[p-m] = 0;
323 if (strrcmp(s, "include/linux/autoconf.h") &&
324 strrcmp(s, "arch/um/include/uml-config.h") &&
325 strrcmp(s, ".ver")) {
326 printf(" %s \\\n", s);
327 do_config_file(s);
328 }
329 m = p + 1;
330 }
331 printf("\n%s: $(deps_%s)\n\n", target, target);
332 printf("$(deps_%s):\n", target);
333}
334
335void print_deps(void)
336{
337 struct stat st;
338 int fd;
339 void *map;
340
341 fd = open(depfile, O_RDONLY);
342 if (fd < 0) {
343 fprintf(stderr, "fixdep: ");
344 perror(depfile);
345 exit(2);
346 }
347 fstat(fd, &st);
348 if (st.st_size == 0) {
349 fprintf(stderr,"fixdep: %s is empty\n",depfile);
350 close(fd);
351 return;
352 }
353 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
354 if ((long) map == -1) {
355 perror("fixdep: mmap");
356 close(fd);
357 return;
358 }
359
360 parse_dep_file(map, st.st_size);
361
362 munmap(map, st.st_size);
363
364 close(fd);
365}
366
367void traps(void)
368{
369 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
370
371 if (*(int *)test != INT_CONF) {
372 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n",
373 *(int *)test);
374 exit(2);
375 }
376}
377
378int main(int argc, char *argv[])
379{
380 traps();
381
382 if (argc != 4)
383 usage();
384
385 depfile = argv[1];
386 target = argv[2];
387 cmdline = argv[3];
388
389 print_cmdline();
390 print_deps();
391
392 return 0;
393}