1 /*
2  * Copyright (c) 2018 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/queue.h>
18 #include <sys/stat.h>
19 
20 #include <stdio.h>
21 #include <stdlib.h>
22 #include <sha1.h>
23 #include <zlib.h>
24 
25 #include "got_object.h"
26 
27 #include "got_error.h"
28 #include "got_lib_delta.h"
29 #include "got_lib_inflate.h"
30 #include "got_lib_object.h"
31 #include "got_lib_diffoffset.h"
32 
33 /*
34  * A line offset between an old file and a new file, derived from diff chunk
35  * header info @@ -old_lineno,old_length +new_lineno,new_length @@ in a diff
36  * with zero context lines (as in diff -U0 old-file new-file).
37  */
38 struct got_diffoffset_chunk {
39 	int lineno;	/* first line which has shifted */
40 	int offset;	/* applies to subsequent lines until next chunk */
41 	SIMPLEQ_ENTRY(got_diffoffset_chunk) entry;
42 };
43 
44 static struct got_diffoffset_chunk *
45 alloc_chunk(int lineno, int offset)
46 {
47 	struct got_diffoffset_chunk *chunk;
48 
49 	chunk = calloc(1, sizeof(*chunk));
50 	if (chunk == NULL)
51 		return NULL;
52 
53 	chunk->lineno = lineno;
54 	chunk->offset = offset;
55 
56 	return chunk;
57 }
58 
59 const struct got_error *
60 got_diffoffset_alloc(struct got_diffoffset_chunks **chunks)
61 {
62 	const struct got_error *err = NULL;
63 
64 	*chunks = calloc(1, sizeof(**chunks));
65 	if (*chunks == NULL) {
66 		err = got_error_from_errno("calloc");
67 		return err;
68 	}
69 
70 	SIMPLEQ_INIT(*chunks);
71 	return NULL;
72 }
73 
74 void
75 got_diffoffset_free(struct got_diffoffset_chunks *chunks)
76 {
77 	struct got_diffoffset_chunk *chunk;
78 
79 	while (!SIMPLEQ_EMPTY(chunks)) {
80 		chunk = SIMPLEQ_FIRST(chunks);
81 		SIMPLEQ_REMOVE_HEAD(chunks, entry);
82 		free(chunk);
83 	}
84 	free(chunks);
85 }
86 
87 const struct got_error *
88 add_chunk(struct got_diffoffset_chunks *chunks, int lineno, int offset)
89 {
90 	struct got_diffoffset_chunk *chunk;
91 
92 	chunk = alloc_chunk(lineno, offset);
93 	if (chunk == NULL)
94 		return got_error_from_errno("alloc_chunk");
95 
96 	SIMPLEQ_INSERT_TAIL(chunks, chunk, entry);
97 	return NULL;
98 }
99 
100 
101 const struct got_error *
102 got_diffoffset_add(struct got_diffoffset_chunks *chunks,
103     int old_lineno, int old_length, int new_lineno, int new_length)
104 {
105 	const struct got_error *err = NULL;
106 	int offset;
107 
108 	if (old_length != 0) {
109 		offset = new_lineno - old_lineno;
110 		if (offset != 0) {
111 			err = add_chunk(chunks, old_lineno, offset);
112 			if (err)
113 				return err;
114 		}
115 	} else {
116 		offset = new_length;
117 		if (offset != 0) {
118 			err = add_chunk(chunks, old_lineno, offset);
119 			if (err)
120 				return err;
121 		}
122 		if (old_lineno == new_lineno)
123 			return NULL;
124 	}
125 
126 	offset = new_lineno - old_lineno + new_length - old_length;
127 	if (offset != 0)
128 		err = add_chunk(chunks, old_lineno + new_length, offset);
129 
130 	return err;
131 }
132 
133 int
134 got_diffoffset_get(struct got_diffoffset_chunks *chunks, int lineno)
135 {
136 	struct got_diffoffset_chunk *chunk;
137 	int offset = 0;
138 
139 	SIMPLEQ_FOREACH(chunk, chunks, entry) {
140 		if (chunk->lineno > lineno)
141 			break;
142 		offset += chunk->offset;
143 	}
144 
145 	return lineno + offset;
146 }