1// SPDX-License-Identifier: GPL-2.0
2/*
3 * "Optimize" a list of dependencies as spit out by gcc -MD
4 * for the build framework.
5 *
6 * Original author:
7 *   Copyright    2002 by Kai Germaschewski  <kai.germaschewski@gmx.de>
8 *
9 * This code has been borrowed from kbuild's fixdep (scripts/basic/fixdep.c),
10 * Please check it for detailed explanation. This fixdep borow only the
11 * base transformation of dependecies without the CONFIG mangle.
12 */
13
14#include <sys/types.h>
15#include <sys/stat.h>
16#include <sys/mman.h>
17#include <unistd.h>
18#include <fcntl.h>
19#include <string.h>
20#include <stdlib.h>
21#include <stdio.h>
22#include <limits.h>
23
24char *target;
25char *depfile;
26char *cmdline;
27
28static void usage(void)
29{
30	fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
31	exit(1);
32}
33
34/*
35 * Print out the commandline prefixed with cmd_<target filename> :=
36 */
37static void print_cmdline(void)
38{
39	printf("cmd_%s := %s\n\n", target, cmdline);
40}
41
42/*
43 * Important: The below generated source_foo.o and deps_foo.o variable
44 * assignments are parsed not only by make, but also by the rather simple
45 * parser in scripts/mod/sumversion.c.
46 */
47static void parse_dep_file(void *map, size_t len)
48{
49	char *m = map;
50	char *end = m + len;
51	char *p;
52	char s[PATH_MAX];
53	int is_target, has_target = 0;
54	int saw_any_target = 0;
55	int is_first_dep = 0;
56
57	while (m < end) {
58		/* Skip any "white space" */
59		while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
60			m++;
61		/* Find next "white space" */
62		p = m;
63		while (p < end && *p != ' ' && *p != '\\' && *p != '\n')
64			p++;
65		/* Is the token we found a target name? */
66		is_target = (*(p-1) == ':');
67		/* Don't write any target names into the dependency file */
68		if (is_target) {
69			/* The /next/ file is the first dependency */
70			is_first_dep = 1;
71			has_target = 1;
72		} else if (has_target) {
73			/* Save this token/filename */
74			memcpy(s, m, p-m);
75			s[p - m] = 0;
76
77			/*
78			 * Do not list the source file as dependency,
79			 * so that kbuild is not confused if a .c file
80			 * is rewritten into .S or vice versa. Storing
81			 * it in source_* is needed for modpost to
82			 * compute srcversions.
83			 */
84			if (is_first_dep) {
85				/*
86				 * If processing the concatenation of
87				 * multiple dependency files, only
88				 * process the first target name, which
89				 * will be the original source name,
90				 * and ignore any other target names,
91				 * which will be intermediate temporary
92				 * files.
93				 */
94				if (!saw_any_target) {
95					saw_any_target = 1;
96					printf("source_%s := %s\n\n",
97						target, s);
98					printf("deps_%s := \\\n",
99						target);
100				}
101				is_first_dep = 0;
102			} else
103				printf("  %s \\\n", s);
104		}
105		/*
106		 * Start searching for next token immediately after the first
107		 * "whitespace" character that follows this token.
108		 */
109		m = p + 1;
110	}
111
112	if (!saw_any_target) {
113		fprintf(stderr, "fixdep: parse error; no targets found\n");
114		exit(1);
115	}
116
117	printf("\n%s: $(deps_%s)\n\n", target, target);
118	printf("$(deps_%s):\n", target);
119}
120
121static void print_deps(void)
122{
123	struct stat st;
124	int fd;
125	void *map;
126
127	fd = open(depfile, O_RDONLY);
128	if (fd < 0) {
129		fprintf(stderr, "fixdep: error opening depfile: ");
130		perror(depfile);
131		exit(2);
132	}
133	if (fstat(fd, &st) < 0) {
134		fprintf(stderr, "fixdep: error fstat'ing depfile: ");
135		perror(depfile);
136		exit(2);
137	}
138	if (st.st_size == 0) {
139		fprintf(stderr, "fixdep: %s is empty\n", depfile);
140		close(fd);
141		return;
142	}
143	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
144	if ((long) map == -1) {
145		perror("fixdep: mmap");
146		close(fd);
147		return;
148	}
149
150	parse_dep_file(map, st.st_size);
151
152	munmap(map, st.st_size);
153
154	close(fd);
155}
156
157int main(int argc, char **argv)
158{
159	if (argc != 4)
160		usage();
161
162	depfile = argv[1];
163	target  = argv[2];
164	cmdline = argv[3];
165
166	print_cmdline();
167	print_deps();
168
169	return 0;
170}
171