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 <errno.h>
19 #include <inttypes.h>
20 #include <stdbool.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <unistd.h>
24 
25 #include <diff/arraylist.h>
26 #include <diff/diff_main.h>
27 #include <diff/diff_output.h>
28 
29 #include "diff_internal.h"
30 
31 static int
32 get_atom_byte(int *ch, struct diff_atom *atom, off_t off)
33 {
34 	off_t cur;
35 
36 	if (atom->at != NULL) {
37 		*ch = atom->at[off];
38 		return 0;
39 	}
40 
41 	cur = ftello(atom->d->root->f);
42 	if (cur == -1)
43 		return errno;
44 
45 	if (cur != atom->pos + off &&
46 	    fseeko(atom->d->root->f, atom->pos + off, SEEK_SET) == -1)
47 		return errno;
48 
49 	*ch = fgetc(atom->d->root->f);
50 	if (*ch == EOF && ferror(atom->d->root->f))
51 		return errno;
52 
53 	return 0;
54 }
55 
56 int
57 diff_output_lines(FILE *dest, const char *prefix, struct diff_atom *start_atom,
58 		  unsigned int count)
59 {
60 	struct diff_atom *atom;
61 	int rc;
62 	foreach_diff_atom(atom, start_atom, count) {
63 		fprintf(dest, "%s", prefix);
64 		int i, ch;
65 		unsigned int len = atom->len;
66 		if (len) {
67 			rc = get_atom_byte(&ch, atom, len - 1);
68 			if (rc)
69 				return rc;
70 			if (ch == '\n')
71 				len--;
72 			if (len) {
73 				rc = get_atom_byte(&ch, atom, len - 1);
74 				if (rc)
75 					return rc;
76 				if (ch == '\r')
77 					len--;
78 			}
79 		}
80 
81 		for (i = 0; i < len; i++) {
82 			rc = get_atom_byte(&ch, atom, i);
83 			if (rc)
84 				return rc;
85 			if ((ch < 0x20 || ch >= 0x7f) && ch != '\t')
86 				fprintf(dest, "\\x%02x", (unsigned char)ch);
87 			else
88 				fprintf(dest, "%c", ch);
89 		}
90 		fprintf(dest, "\n");
91 	}
92 
93 	return 0;
94 }