1 /* Commandline diff utility to test diff implementations. */
2 /*
3  * Copyright (c) 2018 Martin Pieuchot
4  * Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
5  *
6  * Permission to use, copy, modify, and distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 
19 #include <sys/mman.h>
20 #include <sys/stat.h>
21 
22 #include <err.h>
23 #include <fcntl.h>
24 #include <inttypes.h>
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <unistd.h>
28 
29 #include <diff/diff_main.h>
30 #include <diff/diff_output.h>
31 
32 #ifdef __linux__
33 /* stupid shims to compile and test on linux */
34 #define __dead
35 
36 static const char *getprogname()
37 {
38 	return "diff";
39 }
40 #endif
41 
42 __dead void	 usage(void);
43 int		 diffreg(char *, char *, int);
44 char		*mmapfile(const char *, struct stat *);
45 
46 __dead void
47 usage(void)
48 {
49 	fprintf(stderr, "usage: %s file1 file2\n", getprogname());
50 	exit(1);
51 }
52 
53 int
54 main(int argc, char *argv[])
55 {
56 	int ch;
57 
58 	while ((ch = getopt(argc, argv, "")) != -1) {
59 		switch (ch) {
60 		default:
61 			usage();
62 		}
63 	}
64 
65 	argc -= optind;
66 	argv += optind;
67 
68 	if (argc != 2)
69 		usage();
70 
71 	return diffreg(argv[0], argv[1], 0);
72 }
73 
74 const struct diff_algo_config myers, patience, myers_divide;
75 
76 const struct diff_algo_config myers = (struct diff_algo_config){
77 	.impl = diff_algo_myers,
78 	.permitted_state_size = 1024 * 1024 * sizeof(int),
79 	.fallback_algo = &patience,
80 };
81 
82 const struct diff_algo_config patience = (struct diff_algo_config){
83 	.impl = diff_algo_patience,
84 	.inner_algo = &patience,	// After subdivision, do Patience again.
85 	.fallback_algo = &myers_divide, // If subdivision failed, do Myers Divide et Impera.
86 };
87 
88 const struct diff_algo_config myers_divide = (struct diff_algo_config){
89 	.impl = diff_algo_myers_divide,
90 	.inner_algo = &myers,		// When division succeeded, start from the top.
91 					// (fallback_algo = NULL implies diff_algo_none).
92 };
93 
94 const struct diff_config diff_config = {
95 	.atomize_func = diff_atomize_text_by_line,
96 	.algo = &myers,
97 };
98 
99 int
100 diffreg(char *file1, char *file2, int flags)
101 {
102 	char *str1, *str2;
103 	struct stat st1, st2;
104 	struct diff_input_info info = {
105 		.left_path = file1,
106 		.right_path = file2,
107 	};
108 
109 	str1 = mmapfile(file1, &st1);
110 	str2 = mmapfile(file2, &st2);
111 
112 	diff_unidiff(stdout, &diff_config, &info, str1, st1.st_size, str2, st2.st_size, 3);
113 
114 	munmap(str1, st1.st_size);
115 	munmap(str2, st2.st_size);
116 
117 	return 0;
118 }
119 
120 char *
121 mmapfile(const char *path, struct stat *st)
122 {
123 	int			 fd;
124 	char			*p;
125 
126 	fd = open(path, O_RDONLY);
127 	if (fd == -1)
128 		err(2, "%s", path);
129 
130 	if (fstat(fd, st) == -1)
131 		err(2, "%s", path);
132 
133 	if ((uintmax_t)st->st_size > SIZE_MAX)
134 		errx(2, "%s: file too big to fit memory", path);
135 
136 	p = mmap(NULL, st->st_size, PROT_READ, MAP_PRIVATE, fd, 0);
137 	if (p == MAP_FAILED)
138 		err(2, "mmap");
139 
140 	close(fd);
141 
142 	return p;
143 }