1/*
  2 * "Optimize" a list of dependencies as spit out by gcc -MD
  3 * for the build framework.
  4 *
  5 * Original author:
  6 *   Copyright    2002 by Kai Germaschewski  <kai.germaschewski@gmx.de>
  7 *
  8 * This code has been borrowed from kbuild's fixdep (scripts/basic/fixdep.c),
  9 * Please check it for detailed explanation. This fixdep borow only the
 10 * base transformation of dependecies without the CONFIG mangle.
 11 */
 12
 13#include <sys/types.h>
 14#include <sys/stat.h>
 15#include <sys/mman.h>
 16#include <unistd.h>
 17#include <fcntl.h>
 18#include <string.h>
 19#include <stdlib.h>
 20#include <stdio.h>
 21#include <limits.h>
 22
 23char *target;
 24char *depfile;
 25char *cmdline;
 26
 27static void usage(void)
 28{
 29	fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
 30	exit(1);
 31}
 32
 33/*
 34 * Print out the commandline prefixed with cmd_<target filename> :=
 35 */
 36static void print_cmdline(void)
 37{
 38	printf("cmd_%s := %s\n\n", target, cmdline);
 39}
 40
 41/*
 42 * Important: The below generated source_foo.o and deps_foo.o variable
 43 * assignments are parsed not only by make, but also by the rather simple
 44 * parser in scripts/mod/sumversion.c.
 45 */
 46static void parse_dep_file(void *map, size_t len)
 47{
 48	char *m = map;
 49	char *end = m + len;
 50	char *p;
 51	char s[PATH_MAX];
 52	int is_target, has_target = 0;
 53	int saw_any_target = 0;
 54	int is_first_dep = 0;
 55
 56	while (m < end) {
 57		/* Skip any "white space" */
 58		while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
 59			m++;
 60		/* Find next "white space" */
 61		p = m;
 62		while (p < end && *p != ' ' && *p != '\\' && *p != '\n')
 63			p++;
 64		/* Is the token we found a target name? */
 65		is_target = (*(p-1) == ':');
 66		/* Don't write any target names into the dependency file */
 67		if (is_target) {
 68			/* The /next/ file is the first dependency */
 69			is_first_dep = 1;
 70			has_target = 1;
 71		} else if (has_target) {
 72			/* Save this token/filename */
 73			memcpy(s, m, p-m);
 74			s[p - m] = 0;
 75
 76			/*
 77			 * Do not list the source file as dependency,
 78			 * so that kbuild is not confused if a .c file
 79			 * is rewritten into .S or vice versa. Storing
 80			 * it in source_* is needed for modpost to
 81			 * compute srcversions.
 82			 */
 83			if (is_first_dep) {
 84				/*
 85				 * If processing the concatenation of
 86				 * multiple dependency files, only
 87				 * process the first target name, which
 88				 * will be the original source name,
 89				 * and ignore any other target names,
 90				 * which will be intermediate temporary
 91				 * files.
 92				 */
 93				if (!saw_any_target) {
 94					saw_any_target = 1;
 95					printf("source_%s := %s\n\n",
 96						target, s);
 97					printf("deps_%s := \\\n",
 98						target);
 99				}
100				is_first_dep = 0;
101			} else
102				printf("  %s \\\n", s);
103		}
104		/*
105		 * Start searching for next token immediately after the first
106		 * "whitespace" character that follows this token.
107		 */
108		m = p + 1;
109	}
110
111	if (!saw_any_target) {
112		fprintf(stderr, "fixdep: parse error; no targets found\n");
113		exit(1);
114	}
115
116	printf("\n%s: $(deps_%s)\n\n", target, target);
117	printf("$(deps_%s):\n", target);
118}
119
120static void print_deps(void)
121{
122	struct stat st;
123	int fd;
124	void *map;
125
126	fd = open(depfile, O_RDONLY);
127	if (fd < 0) {
128		fprintf(stderr, "fixdep: error opening depfile: ");
129		perror(depfile);
130		exit(2);
131	}
132	if (fstat(fd, &st) < 0) {
133		fprintf(stderr, "fixdep: error fstat'ing depfile: ");
134		perror(depfile);
135		exit(2);
136	}
137	if (st.st_size == 0) {
138		fprintf(stderr, "fixdep: %s is empty\n", depfile);
139		close(fd);
140		return;
141	}
142	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
143	if ((long) map == -1) {
144		perror("fixdep: mmap");
145		close(fd);
146		return;
147	}
148
149	parse_dep_file(map, st.st_size);
150
151	munmap(map, st.st_size);
152
153	close(fd);
154}
155
156int main(int argc, char **argv)
157{
158	if (argc != 4)
159		usage();
160
161	depfile = argv[1];
162	target  = argv[2];
163	cmdline = argv[3];
164
165	print_cmdline();
166	print_deps();
167
168	return 0;
169}