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
|
/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include "libbb.h"
ssize_t safe_read(int fd, void *buf, size_t count)
{
ssize_t n;
do {
n = read(fd, buf, count);
} while (n < 0 && errno == EINTR);
return n;
}
/*
* Read all of the supplied buffer from a file.
* This does multiple reads as necessary.
* Returns the amount read, or -1 on an error.
* A short read is returned on an end of file.
*/
ssize_t full_read(int fd, void *buf, size_t len)
{
ssize_t cc;
ssize_t total;
total = 0;
while (len) {
cc = safe_read(fd, buf, len);
if (cc < 0)
return cc; /* read() returns -1 on failure. */
if (cc == 0)
break;
buf = ((char *)buf) + cc;
total += cc;
len -= cc;
}
return total;
}
// Die with an error message if we can't read the entire buffer.
void xread(int fd, void *buf, size_t count)
{
if (count) {
ssize_t size = full_read(fd, buf, count);
if (size != count)
bb_error_msg_and_die("short read");
}
}
// Die with an error message if we can't read one character.
unsigned char xread_char(int fd)
{
char tmp;
xread(fd, &tmp, 1);
return tmp;
}
// Read one line a-la fgets. Works only on seekable streams
char *reads(int fd, char *buffer, size_t size)
{
char *p;
if (size < 2)
return NULL;
size = full_read(fd, buffer, size-1);
if ((ssize_t)size <= 0)
return NULL;
buffer[size] = '\0';
p = strchr(buffer, '\n');
if (p) {
off_t offset;
*p++ = '\0';
// avoid incorrect (unsigned) widening
offset = (off_t)(p-buffer) - (off_t)size;
// set fd position right after '\n'
if (offset && lseek(fd, offset, SEEK_CUR) == (off_t)-1)
return NULL;
}
return buffer;
}
ssize_t read_close(int fd, void *buf, size_t size)
{
int e;
size = full_read(fd, buf, size);
e = errno;
close(fd);
errno = e;
return size;
}
ssize_t open_read_close(const char *filename, void *buf, size_t size)
{
int fd = open(filename, O_RDONLY);
if (fd < 0)
return fd;
return read_close(fd, buf, size);
}
void *xmalloc_open_read_close(const char *filename, size_t *sizep)
{
char *buf;
size_t size = sizep ? *sizep : INT_MAX;
int fd = xopen(filename, O_RDONLY);
/* /proc/N/stat files report len 0 here */
/* In order to make such files readable, we add small const */
off_t len = xlseek(fd, 0, SEEK_END) + 256;
xlseek(fd, 0, SEEK_SET);
if (len > size)
bb_error_msg_and_die("file '%s' is too big", filename);
size = len;
buf = xmalloc(size + 1);
size = read_close(fd, buf, size);
if ((ssize_t)size < 0)
bb_perror_msg_and_die("'%s'", filename);
xrealloc(buf, size + 1);
buf[size] = '\0';
if (sizep) *sizep = size;
return buf;
}
|
