summaryrefslogtreecommitdiff
path: root/tree-walk.c
blob: 8d4b67317f21508a105175686c7ec98a090ed9b5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
#include "cache.h"
#include "tree-walk.h"
#include "tree.h"

static const char *get_mode(const char *str, unsigned int *modep)
{
	unsigned char c;
	unsigned int mode = 0;

	while ((c = *str++) != ' ') {
		if (c < '0' || c > '7')
			return NULL;
		mode = (mode << 3) + (c - '0');
	}
	*modep = mode;
	return str;
}

static void decode_tree_entry(struct tree_desc *desc, const void *buf, unsigned long size)
{
	const char *path;
	unsigned int mode, len;

	path = get_mode(buf, &mode);
	if (!path)
		die("corrupt tree file");
	len = strlen(path) + 1;

	/* Initialize the descriptor entry */
	desc->entry.path = path;
	desc->entry.mode = mode;
	desc->entry.sha1 = (const unsigned char *)(path + len);
}

void init_tree_desc(struct tree_desc *desc, const void *buffer, unsigned long size)
{
	desc->buffer = buffer;
	desc->size = size;
	if (size)
		decode_tree_entry(desc, buffer, size);
}

void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1)
{
	unsigned long size = 0;
	void *buf = NULL;

	if (sha1) {
		buf = read_object_with_reference(sha1, tree_type, &size, NULL);
		if (!buf)
			die("unable to read tree %s", sha1_to_hex(sha1));
	}
	init_tree_desc(desc, buf, size);
	return buf;
}

static int entry_compare(struct name_entry *a, struct name_entry *b)
{
	return base_name_compare(
			a->path, tree_entry_len(a->path, a->sha1), a->mode,
			b->path, tree_entry_len(b->path, b->sha1), b->mode);
}

static void entry_clear(struct name_entry *a)
{
	memset(a, 0, sizeof(*a));
}

static void entry_extract(struct tree_desc *t, struct name_entry *a)
{
	*a = t->entry;
}

void update_tree_entry(struct tree_desc *desc)
{
	const void *buf = desc->buffer;
	const unsigned char *end = desc->entry.sha1 + 20;
	unsigned long size = desc->size;
	unsigned long len = end - (const unsigned char *)buf;

	if (size < len)
		die("corrupt tree file");
	buf = end;
	size -= len;
	desc->buffer = buf;
	desc->size = size;
	if (size)
		decode_tree_entry(desc, buf, size);
}

int tree_entry(struct tree_desc *desc, struct name_entry *entry)
{
	if (!desc->size)
		return 0;

	*entry = desc->entry;
	update_tree_entry(desc);
	return 1;
}

void traverse_trees(int n, struct tree_desc *t, const char *base, traverse_callback_t callback)
{
	struct name_entry *entry = xmalloc(n*sizeof(*entry));

	for (;;) {
		unsigned long mask = 0;
		int i, last;

		last = -1;
		for (i = 0; i < n; i++) {
			if (!t[i].size)
				continue;
			entry_extract(t+i, entry+i);
			if (last >= 0) {
				int cmp = entry_compare(entry+i, entry+last);

				/*
				 * Is the new name bigger than the old one?
				 * Ignore it
				 */
				if (cmp > 0)
					continue;
				/*
				 * Is the new name smaller than the old one?
				 * Ignore all old ones
				 */
				if (cmp < 0)
					mask = 0;
			}
			mask |= 1ul << i;
			last = i;
		}
		if (!mask)
			break;

		/*
		 * Update the tree entries we've walked, and clear
		 * all the unused name-entries.
		 */
		for (i = 0; i < n; i++) {
			if (mask & (1ul << i)) {
				update_tree_entry(t+i);
				continue;
			}
			entry_clear(entry + i);
		}
		callback(n, mask, entry, base);
	}
	free(entry);
}

static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
{
	int namelen = strlen(name);
	while (t->size) {
		const char *entry;
		const unsigned char *sha1;
		int entrylen, cmp;

		sha1 = tree_entry_extract(t, &entry, mode);
		update_tree_entry(t);
		entrylen = tree_entry_len(entry, sha1);
		if (entrylen > namelen)
			continue;
		cmp = memcmp(name, entry, entrylen);
		if (cmp > 0)
			continue;
		if (cmp < 0)
			break;
		if (entrylen == namelen) {
			hashcpy(result, sha1);
			return 0;
		}
		if (name[entrylen] != '/')
			continue;
		if (!S_ISDIR(*mode))
			break;
		if (++entrylen == namelen) {
			hashcpy(result, sha1);
			return 0;
		}
		return get_tree_entry(sha1, name + entrylen, result, mode);
	}
	return -1;
}

int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned char *sha1, unsigned *mode)
{
	int retval;
	void *tree;
	unsigned long size;
	struct tree_desc t;
	unsigned char root[20];

	tree = read_object_with_reference(tree_sha1, tree_type, &size, root);
	if (!tree)
		return -1;

	if (name[0] == '\0') {
		hashcpy(sha1, root);
		return 0;
	}

	init_tree_desc(&t, tree, size);
	retval = find_tree_entry(&t, name, sha1, mode);
	free(tree);
	return retval;
}