blob: 4e770eb4109c54a1f5b87563be8d5c6964a3998b (
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
|
#include <config.h>
#include "areadlink.h"
#include <string.h>
#include <errno.h>
#include <limits.h>
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#ifndef SIZE_MAX
# define SIZE_MAX ((size_t) -1)
#endif
#ifndef SSIZE_MAX
# define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
#endif
char *
areadlink (char const *filename)
{
#define INITIAL_BUF_SIZE 1024
char initial_buf[INITIAL_BUF_SIZE];
char *buffer = initial_buf;
size_t buf_size = sizeof (initial_buf);
while (1)
{
ssize_t link_length = readlink (filename, buffer, buf_size);
if (link_length < 0 && errno != ERANGE)
{
if (buffer != initial_buf)
{
int saved_errno = errno;
free (buffer);
errno = saved_errno;
}
return NULL;
}
if ((size_t) link_length < buf_size)
{
buffer[link_length++] = '\0';
if (buffer == initial_buf)
{
buffer = (char *) malloc (link_length);
if (buffer == NULL)
return NULL;
memcpy (buffer, initial_buf, link_length);
}
else
{
if ((size_t) link_length < buf_size)
{
char *smaller_buffer = (char *) realloc (buffer, link_length);
if (smaller_buffer != NULL)
buffer = smaller_buffer;
}
}
return buffer;
}
if (buffer != initial_buf)
free (buffer);
buf_size *= 2;
if (SSIZE_MAX < buf_size || (SIZE_MAX / 2 < SSIZE_MAX && buf_size == 0))
{
errno = ENOMEM;
return NULL;
}
buffer = (char *) malloc (buf_size);
if (buffer == NULL)
return NULL;
}
}
|