1 /* Common parts for printing diff output */
2 /*
3  * Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include <unistd.h>
19 
20 #include <diff/diff_output.h>
21 
22 static char
23 get_atom_byte(struct diff_atom *atom, off_t off)
24 {
25 	char ch;
26 	off_t cur;
27 
28 	if (atom->at != NULL)
29 		return atom->at[off];
30 
31 	cur = lseek(atom->d->root->fd, 0, SEEK_CUR);
32 	if (cur == -1)
33 		abort(); /* XXX cannot return error */
34 
35 	if (cur != atom->pos + off &&
36 	    lseek(atom->d->root->fd, atom->pos + off, SEEK_SET) == -1)
37 		abort(); /* XXX cannot return error */
38 
39 	if (read(atom->d->root->fd, &ch, sizeof(ch)) == -1)
40 		abort(); /* XXX cannot return error */
41 
42 	return ch;
43 }
44 
45 void
46 diff_output_lines(FILE *dest, const char *prefix, struct diff_atom *start_atom,
47 		  unsigned int count)
48 {
49 	struct diff_atom *atom;
50 	foreach_diff_atom(atom, start_atom, count) {
51 		fprintf(dest, "%s", prefix);
52 		int i;
53 		unsigned int len = atom->len;
54 		if (len) {
55 			char ch;
56 			ch = get_atom_byte(atom, len - 1);
57 			if (ch == '\n')
58 				len--;
59 			if (len) {
60 				ch = get_atom_byte(atom, len - 1);
61 				if (ch == '\r')
62 					len--;
63 			}
64 		}
65 
66 		for (i = 0; i < len; i++) {
67 			char c = get_atom_byte(atom, i);
68 			if ((c < 0x20 || c >= 0x7f) && c != '\t')
69 				fprintf(dest, "\\x%02x", (unsigned char)c);
70 			else
71 				fprintf(dest, "%c", c);
72 		}
73 		fprintf(dest, "\n");
74 	}
75 }