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 <arraylist.h>
26 #include <diff_main.h>
27 #include <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(struct diff_output_info *outinfo, FILE *dest,
58 		  const char *prefix, struct diff_atom *start_atom,
59 		  unsigned int count)
60 {
61 	struct diff_atom *atom;
62 	off_t outoff = 0, *offp;
63 	int rc;
64 
65 	if (outinfo && outinfo->line_offsets.len > 0) {
66 		unsigned int idx = outinfo->line_offsets.len - 1;
67 		outoff = outinfo->line_offsets.head[idx];
68 	}
69 
70 	foreach_diff_atom(atom, start_atom, count) {
71 		off_t outlen = 0;
72 		int i, ch;
73 		unsigned int len = atom->len;
74 		rc = fprintf(dest, "%s", prefix);
75 		if (rc < 0)
76 			return errno;
77 		outlen += rc;
78 		if (len) {
79 			rc = get_atom_byte(&ch, atom, len - 1);
80 			if (rc)
81 				return rc;
82 			if (ch == '\n')
83 				len--;
84 			if (len) {
85 				rc = get_atom_byte(&ch, atom, len - 1);
86 				if (rc)
87 					return rc;
88 				if (ch == '\r')
89 					len--;
90 			}
91 		}
92 
93 		for (i = 0; i < len; i++) {
94 			rc = get_atom_byte(&ch, atom, i);
95 			if (rc)
96 				return rc;
97 			if ((ch < 0x20 || ch >= 0x7f) && ch != '\t')
98 				rc = fprintf(dest, "\\x%02x", (unsigned char)ch);
99 			else
100 				rc = fprintf(dest, "%c", ch);
101 			if (rc < 0)
102 				return errno;
103 			outlen += rc;
104 		}
105 		rc = fprintf(dest, "\n");
106 		if (rc < 0)
107 			return errno;
108 		outlen += rc;
109 		if (outinfo) {
110 			ARRAYLIST_ADD(offp, outinfo->line_offsets);
111 			if (offp == NULL)
112 				return ENOMEM;
113 			outoff += outlen;
114 			*offp = outoff;
115 		}
116 	}
117 
118 	return DIFF_RC_OK;
119 }
120 
121 int
122 diff_output_chunk_left_version(struct diff_output_info **output_info,
123 			       FILE *dest,
124 			       const struct diff_input_info *info,
125 			       const struct diff_result *result,
126 			       const struct diff_chunk_context *cc)
127 {
128 	int rc, c_idx;
129 	struct diff_output_info *outinfo = NULL;
130 
131 	if (diff_range_empty(&cc->left))
132 		return DIFF_RC_OK;
133 
134 	if (output_info) {
135 		*output_info = diff_output_info_alloc();
136 		if (*output_info == NULL)
137 			return ENOMEM;
138 		outinfo = *output_info;
139 	}
140 
141 	/* Write out all chunks on the left side. */
142 	for (c_idx = cc->chunk.start; c_idx < cc->chunk.end; c_idx++) {
143 		const struct diff_chunk *c = &result->chunks.head[c_idx];
144 
145 		if (c->left_count) {
146 			rc = diff_output_lines(outinfo, dest, "",
147 			    c->left_start, c->left_count);
148 			if (rc)
149 				return rc;
150 		}
151 	}
152 
153 	return DIFF_RC_OK;
154 }
155 
156 int
157 diff_output_chunk_right_version(struct diff_output_info **output_info,
158 				FILE *dest,
159 				const struct diff_input_info *info,
160 				const struct diff_result *result,
161 				const struct diff_chunk_context *cc)
162 {
163 	int rc, c_idx;
164 	struct diff_output_info *outinfo = NULL;
165 
166 	if (diff_range_empty(&cc->right))
167 		return DIFF_RC_OK;
168 
169 	if (output_info) {
170 		*output_info = diff_output_info_alloc();
171 		if (*output_info == NULL)
172 			return ENOMEM;
173 		outinfo = *output_info;
174 	}
175 
176 	/* Write out all chunks on the right side. */
177 	for (c_idx = cc->chunk.start; c_idx < cc->chunk.end; c_idx++) {
178 		const struct diff_chunk *c = &result->chunks.head[c_idx];
179 
180 		if (c->right_count) {
181 			rc = diff_output_lines(outinfo, dest, "", c->right_start,
182 			    c->right_count);
183 			if (rc)
184 				return rc;
185 		}
186 	}
187 
188 	return DIFF_RC_OK;
189 }
190 
191 struct diff_output_info *
192 diff_output_info_alloc(void)
193 {
194 	struct diff_output_info *output_info;
195 	off_t *offp;
196 
197 	output_info = malloc(sizeof(*output_info));
198 	if (output_info != NULL) {
199 		ARRAYLIST_INIT(output_info->line_offsets, 128);
200 		ARRAYLIST_ADD(offp, output_info->line_offsets);
201 		if (offp == NULL) {
202 			diff_output_info_free(output_info);
203 			return NULL;
204 		}
205 		*offp = 0;
206 	}
207 	return output_info;
208 }
209 
210 void
211 diff_output_info_free(struct diff_output_info *output_info)
212 {
213 	ARRAYLIST_FREE(output_info->line_offsets);
214 	free(output_info);
215 }