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 	struct got_diffoffset_chunk *first;
64 
65 	first = alloc_chunk(0, 0);
66 	if (first == NULL)
67 		return got_error_from_errno();
68 
69 	*chunks = calloc(1, sizeof(**chunks));
70 	if (*chunks == NULL) {
71 		err = got_error_from_errno();
72 		free(first);
73 		return err;
74 	}
75 
76 	SIMPLEQ_INIT(*chunks);
77 	SIMPLEQ_INSERT_HEAD(*chunks, first, entry);
78 
79 	return NULL;
80 }
81 
82 void
83 got_diffoffset_free(struct got_diffoffset_chunks *chunks)
84 {
85 	struct got_diffoffset_chunk *chunk;
86 
87 	while (!SIMPLEQ_EMPTY(chunks)) {
88 		chunk = SIMPLEQ_FIRST(chunks);
89 		SIMPLEQ_REMOVE_HEAD(chunks, entry);
90 		free(chunk);
91 	}
92 	free(chunks);
93 }
94 
95 const struct got_error *
96 got_diffoffset_add(struct got_diffoffset_chunks *chunks,
97     int old_lineno, int old_length, int new_lineno, int new_length)
98 {
99 	struct got_diffoffset_chunk *chunk1, *chunk2;
100 
101 	chunk1 = alloc_chunk(old_lineno, new_lineno - old_lineno);
102 	if (chunk1 == NULL)
103 		return got_error_from_errno();
104 
105 	chunk2 = alloc_chunk(old_lineno + old_length,
106 	    new_lineno - old_lineno + new_length - old_length);
107 	if (chunk2 == NULL) {
108 		const struct got_error *err = got_error_from_errno();
109 		free(chunk1);
110 		return err;
111 	}
112 
113 	SIMPLEQ_INSERT_TAIL(chunks, chunk1, entry);
114 	SIMPLEQ_INSERT_TAIL(chunks, chunk2, entry);
115 	return NULL;
116 }
117 
118 int
119 got_diffoffset_get(struct got_diffoffset_chunks *chunks, int lineno)
120 {
121 	struct got_diffoffset_chunk *chunk, *prev;
122 
123 	prev = SIMPLEQ_FIRST(chunks);
124 	SIMPLEQ_FOREACH(chunk, chunks, entry) {
125 		if (chunk->lineno > lineno)
126 			break;
127 		prev = chunk;
128 	}
129 
130 	return lineno + prev->offset;
131 }