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
|
/* libguestfs
* Copyright (C) 2009-2020 Red Hat Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* Implement a private data area where libguestfs C API users can
* attach arbitrary pieces of data to a C<guestfs_h> handle.
*
* For more information see L<guestfs(3)/PRIVATE DATA AREA>.
*
* Language bindings do not generally expose this, largely because in
* non-C languages it is easy to associate data with handles in other
* ways (using hash tables or maps).
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "hash.h"
#include "hash-pjw.h"
#include "guestfs.h"
#include "guestfs-internal.h"
/**
* The private data area is internally stored as a gnulib hash
* table containing C<pda_entry> structures.
*
* Note the private data area is allocated lazily, since the vast
* majority of callers will never use it. This means C<g-E<gt>pda> is
* likely to be C<NULL>.
*/
struct pda_entry {
char *key; /* key */
void *data; /* opaque user data pointer */
};
static size_t
hasher (void const *x, size_t table_size)
{
struct pda_entry const *p = x;
return hash_pjw (p->key, table_size);
}
static bool
comparator (void const *x, void const *y)
{
struct pda_entry const *a = x;
struct pda_entry const *b = y;
return STREQ (a->key, b->key);
}
static void
freer (void *x)
{
if (x) {
struct pda_entry *p = x;
free (p->key);
free (p);
}
}
void
guestfs_set_private (guestfs_h *g, const char *key, void *data)
{
ACQUIRE_LOCK_FOR_CURRENT_SCOPE (g);
struct pda_entry *new_entry, *old_entry, *entry;
if (g->pda == NULL) {
g->pda = hash_initialize (16, NULL, hasher, comparator, freer);
if (g->pda == NULL)
g->abort_cb ();
}
new_entry = safe_malloc (g, sizeof *new_entry);
new_entry->key = safe_strdup (g, key);
new_entry->data = data;
old_entry = hash_remove (g->pda, new_entry);
freer (old_entry);
entry = hash_insert (g->pda, new_entry);
if (entry == NULL)
g->abort_cb ();
assert (entry == new_entry);
}
void *
guestfs_get_private (guestfs_h *g, const char *key)
{
ACQUIRE_LOCK_FOR_CURRENT_SCOPE (g);
if (g->pda == NULL)
return NULL; /* no keys have been set */
const struct pda_entry k = { .key = (char *) key };
struct pda_entry *entry = hash_lookup (g->pda, &k);
if (entry)
return entry->data;
else
return NULL;
}
/* Iterator. */
void *
guestfs_first_private (guestfs_h *g, const char **key_rtn)
{
ACQUIRE_LOCK_FOR_CURRENT_SCOPE (g);
if (g->pda == NULL)
return NULL;
g->pda_next = hash_get_first (g->pda);
/* Ignore any keys with NULL data pointers. */
while (g->pda_next && g->pda_next->data == NULL)
g->pda_next = hash_get_next (g->pda, g->pda_next);
if (g->pda_next == NULL)
return NULL;
*key_rtn = g->pda_next->key;
return g->pda_next->data;
}
void *
guestfs_next_private (guestfs_h *g, const char **key_rtn)
{
ACQUIRE_LOCK_FOR_CURRENT_SCOPE (g);
if (g->pda == NULL)
return NULL;
if (g->pda_next == NULL)
return NULL;
/* Walk to the next key with a non-NULL data pointer. */
do {
g->pda_next = hash_get_next (g->pda, g->pda_next);
} while (g->pda_next && g->pda_next->data == NULL);
if (g->pda_next == NULL)
return NULL;
*key_rtn = g->pda_next->key;
return g->pda_next->data;
}
|
