1 /* Output all lines of a diff_result. */
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 <stdint.h>
20 #include <stdio.h>
21 #include <stdbool.h>
22 #include <stdlib.h>
23 
24 #include <arraylist.h>
25 #include <diff_main.h>
26 #include <diff_output.h>
27 
28 #include "diff_internal.h"
29 
30 static int
31 output_plain_chunk(struct diff_output_info *outinfo,
32     FILE *dest, const struct diff_input_info *info,
33     const struct diff_result *result,
34     struct diff_chunk_context *cc)
35 {
36 	off_t outoff = 0, *offp;
37 	int left_start, left_len, right_start, right_len;
38 	int rc;
39 	bool change = false;
40 
41 	left_len = cc->left.end - cc->left.start;
42 	if (left_len < 0)
43 		return EINVAL;
44 	else if (result->left->atoms.len == 0)
45 		left_start = 0;
46 	else if (left_len == 0 && cc->left.start > 0)
47 		left_start = cc->left.start;
48 	else if (cc->left.end > 0)
49 		left_start = cc->left.start + 1;
50 	else
51 		left_start = cc->left.start;
52 
53 	right_len = cc->right.end - cc->right.start;
54 	if (right_len < 0)
55 		return EINVAL;
56 	else if (result->right->atoms.len == 0)
57 		right_start = 0;
58 	else if (right_len == 0 && cc->right.start > 0)
59 		right_start = cc->right.start;
60 	else if (cc->right.end > 0)
61 		right_start = cc->right.start + 1;
62 	else
63 		right_start = cc->right.start;
64 
65 	if (left_len == 0) {
66 		/* addition */
67 		if (right_len == 1) {
68 			rc = fprintf(dest, "%da%d\n", left_start, right_start);
69 		} else {
70 			rc = fprintf(dest, "%da%d,%d\n", left_start,
71 			    right_start, cc->right.end);
72 		}
73 	} else if (right_len == 0) {
74 		/* deletion */
75 		if (left_len == 1) {
76 			rc = fprintf(dest, "%dd%d\n", left_start,
77 			    right_start);
78 		} else {
79 			rc = fprintf(dest, "%d,%dd%d\n", left_start,
80 			    cc->left.end, right_start);
81 		}
82 	} else {
83 		/* change */
84 		change = true;
85 		if (left_len == 1 && right_len == 1) {
86 			rc = fprintf(dest, "%dc%d\n", left_start, right_start);
87 		} else if (left_len == 1) {
88 			rc = fprintf(dest, "%dc%d,%d\n", left_start,
89 			    right_start, cc->right.end);
90 		} else if (right_len == 1) {
91 			rc = fprintf(dest, "%d,%dc%d\n", left_start,
92 			    cc->left.end, right_start);
93 		} else {
94 			rc = fprintf(dest, "%d,%dc%d,%d\n", left_start,
95 			    cc->left.end, right_start, cc->right.end);
96 		}
97 	}
98 
99 	/*
100 	 * Now write out all the joined chunks.
101 	 *
102 	 * If the hunk denotes a change, it will come in the form of a deletion
103 	 * chunk followed by a addition chunk. Print a marker to break up the
104 	 * additions and deletions when this happens.
105 	 */
106 	int c_idx;
107 	for (c_idx = cc->chunk.start; c_idx < cc->chunk.end; c_idx++) {
108 		const struct diff_chunk *c = &result->chunks.head[c_idx];
109 		if (c->left_count && !c->right_count)
110 			rc = diff_output_lines(outinfo, dest,
111 					  c->solved ? "< " : "?",
112 					  c->left_start, c->left_count);
113 		else if (c->right_count && !c->left_count) {
114 			if (change)
115 				fprintf(dest, "---\n");
116 			rc = diff_output_lines(outinfo, dest,
117 					  c->solved ? "> " : "?",
118 					  c->right_start, c->right_count);
119 		}
120 		if (rc)
121 			return rc;
122 		if (cc->chunk.end == result->chunks.len) {
123 			rc = diff_output_trailing_newline_msg(outinfo, dest, c);
124 			if (rc != DIFF_RC_OK)
125 				return rc;
126 		}
127 	}
128 
129 	if (rc < 0)
130 		return errno;
131 	if (outinfo) {
132 		ARRAYLIST_ADD(offp, outinfo->line_offsets);
133 		if (offp == NULL)
134 			return ENOMEM;
135 		outoff += rc;
136 		*offp = outoff;
137 	}
138 
139 	return DIFF_RC_OK;
140 }
141 
142 int
143 diff_output_plain(struct diff_output_info **output_info,
144     FILE *dest, const struct diff_input_info *info,
145     const struct diff_result *result)
146 {
147 	struct diff_output_info *outinfo = NULL;
148 	struct diff_chunk_context cc = {};
149 	int atomizer_flags = (result->left->atomizer_flags|
150 	    result->right->atomizer_flags);
151 	int flags = (result->left->root->diff_flags |
152 	    result->right->root->diff_flags);
153 	bool force_text = (flags & DIFF_FLAG_FORCE_TEXT_DATA);
154 	bool have_binary = (atomizer_flags & DIFF_ATOMIZER_FOUND_BINARY_DATA);
155 	int i, rc;
156 
157 	if (!result)
158 		return EINVAL;
159 	if (result->rc != DIFF_RC_OK)
160 		return result->rc;
161 
162 	if (output_info) {
163 		*output_info = diff_output_info_alloc();
164 		if (*output_info == NULL)
165 			return ENOMEM;
166 		outinfo = *output_info;
167 	}
168 
169 	if (have_binary && !force_text) {
170 		for (i = 0; i < result->chunks.len; i++) {
171 			struct diff_chunk *c = &result->chunks.head[i];
172 			enum diff_chunk_type t = diff_chunk_type(c);
173 
174 			if (t != CHUNK_MINUS && t != CHUNK_PLUS)
175 				continue;
176 
177 			fprintf(dest, "Binary files %s and %s differ\n",
178 			    diff_output_get_label_left(info),
179 			    diff_output_get_label_right(info));
180 			break;
181 		}
182 
183 		return DIFF_RC_OK;
184 	}
185 
186 	for (i = 0; i < result->chunks.len; i++) {
187 		struct diff_chunk *chunk = &result->chunks.head[i];
188 		enum diff_chunk_type t = diff_chunk_type(chunk);
189 		struct diff_chunk_context next;
190 
191 		if (t != CHUNK_MINUS && t != CHUNK_PLUS)
192 			continue;
193 
194 		if (diff_chunk_context_empty(&cc)) {
195 			/* Note down the start point, any number of subsequent
196 			 * chunks may be joined up to this chunk by being
197 			 * directly adjacent. */
198 			diff_chunk_context_get(&cc, result, i, 0);
199 			continue;
200 		}
201 
202 		/* There already is a previous chunk noted down for being
203 		 * printed. Does it join up with this one? */
204 		diff_chunk_context_get(&next, result, i, 0);
205 
206 		if (diff_chunk_contexts_touch(&cc, &next)) {
207 			/* This next context touches or overlaps the previous
208 			 * one, join. */
209 			diff_chunk_contexts_merge(&cc, &next);
210 			/* When we merge the last chunk we can end up with one
211 			 * hanging chunk and have to come back for it after the
212 			 * loop */
213 			continue;
214 		}
215 		rc = output_plain_chunk(outinfo, dest, info, result, &cc);
216 		if (rc != DIFF_RC_OK)
217 			return rc;
218 		cc = next;
219 	}
220 	if (!diff_chunk_context_empty(&cc))
221 		return output_plain_chunk(outinfo, dest, info, result, &cc);
222 	return DIFF_RC_OK;
223 }