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
117/* bbox: not needed
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*/
123
124char *target;
125char *depfile;
126char *cmdline;
127
128void 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 */
138void print_cmdline(void)
139{
140	printf("cmd_%s := %s\n\n", target, cmdline);
141}
142
143char * str_config  = NULL;
144int    size_config = 0;
145int    len_config  = 0;
146
147/*
148 * Grow the configuration string to a desired length.
149 * Usually the first growth is plenty.
150 */
151void 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 */
167int 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 */
183void 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 */
195void clear_config(void)
196{
197	len_config = 0;
198	define_config("", 0);
199}
200
201/*
202 * Record the use of a CONFIG_* word.
203 */
204void 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
225void parse_config_file(char *map, size_t len)
226{
227	/* modified for bbox */
228	char *end_4 = map + len - 4; /* 4 == length of "USE_" */
229	char *end_7 = map + len - 7;
230	char *p = map;
231	char *q;
232	int off;
233
234	for (; p < end_4; p++) {
235		if (p < end_7 && p[6] == '_') {
236			if (!memcmp(p, "CONFIG", 6)) goto conf7;
237			if (!memcmp(p, "ENABLE", 6)) goto conf7;
238		}
239		/* We have at least 5 chars: for() has
240		 * "p < end-4", not "p <= end-4"
241		 * therefore we don't need to check p <= end-5 here */
242		if (p[4] == '_')
243			if (!memcmp(p, "SKIP", 4)) goto conf5;
244		/* Ehhh, gcc is too stupid to just compare it as 32bit int */
245		if (p[0] == 'U')
246			if (!memcmp(p, "USE_", 4)) goto conf4;
247		continue;
248
249	conf4:	off = 4;
250	conf5:	off = 5;
251	conf7:	off = 7;
252		p += off;
253		for (q = p; q < end_4+4; q++) {
254			if (!(isalnum(*q) || *q == '_'))
255				break;
256		}
257		use_config(p, q-p);
258	}
259}
260
261/* test is s ends in sub */
262int strrcmp(char *s, char *sub)
263{
264	int slen = strlen(s);
265	int sublen = strlen(sub);
266
267	if (sublen > slen)
268		return 1;
269
270	return memcmp(s + slen - sublen, sub, sublen);
271}
272
273void do_config_file(char *filename)
274{
275	struct stat st;
276	int fd;
277	void *map;
278
279	fd = open(filename, O_RDONLY);
280	if (fd < 0) {
281		fprintf(stderr, "fixdep: ");
282		perror(filename);
283		exit(2);
284	}
285	fstat(fd, &st);
286	if (st.st_size == 0) {
287		close(fd);
288		return;
289	}
290	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
291	if ((long) map == -1) {
292		perror("fixdep: mmap");
293		close(fd);
294		return;
295	}
296
297	parse_config_file(map, st.st_size);
298
299	munmap(map, st.st_size);
300
301	close(fd);
302}
303
304void parse_dep_file(void *map, size_t len)
305{
306	char *m = map;
307	char *end = m + len;
308	char *p;
309	char s[PATH_MAX];
310
311	p = memchr(m, ':', len);
312	if (!p) {
313		fprintf(stderr, "fixdep: parse error\n");
314		exit(1);
315	}
316	memcpy(s, m, p-m); s[p-m] = 0;
317	printf("deps_%s := \\\n", target);
318	m = p+1;
319
320	clear_config();
321
322	while (m < end) {
323		while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
324			m++;
325		p = m;
326		while (p < end && *p != ' ') p++;
327		if (p == end) {
328			do p--; while (!isalnum(*p));
329			p++;
330		}
331		memcpy(s, m, p-m); s[p-m] = 0;
332		if (strrcmp(s, "include/autoconf.h") &&
333		    strrcmp(s, "arch/um/include/uml-config.h") &&
334		    strrcmp(s, ".ver")) {
335			printf("  %s \\\n", s);
336			do_config_file(s);
337		}
338		m = p + 1;
339	}
340	printf("\n%s: $(deps_%s)\n\n", target, target);
341	printf("$(deps_%s):\n", target);
342}
343
344void print_deps(void)
345{
346	struct stat st;
347	int fd;
348	void *map;
349
350	fd = open(depfile, O_RDONLY);
351	if (fd < 0) {
352		fprintf(stderr, "fixdep: ");
353		perror(depfile);
354		exit(2);
355	}
356	fstat(fd, &st);
357	if (st.st_size == 0) {
358		fprintf(stderr,"fixdep: %s is empty\n",depfile);
359		close(fd);
360		return;
361	}
362	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
363	if ((long) map == -1) {
364		perror("fixdep: mmap");
365		close(fd);
366		return;
367	}
368
369	parse_dep_file(map, st.st_size);
370
371	munmap(map, st.st_size);
372
373	close(fd);
374}
375
376void traps(void)
377{
378/* bbox: not needed
379	static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
380
381	if (*(int *)test != INT_CONF) {
382		fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n",
383			*(int *)test);
384		exit(2);
385	}
386*/
387}
388
389int main(int argc, char **argv)
390{
391	traps();
392
393	if (argc != 4)
394		usage();
395
396	depfile = argv[1];
397	target = argv[2];
398	cmdline = argv[3];
399
400	print_cmdline();
401	print_deps();
402
403	return 0;
404}
405