blob: 1c2945f454101f79853044e565b5c61b83a28e31 [file] [log] [blame]
Denis Vlasenkoea620772006-10-14 02:23:43 +00001/* vi: set sw=4 ts=4: */
2/*
3 * Utility routines.
4 *
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
6 *
7 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
8 */
9
10#include "libbb.h"
11
12ssize_t safe_read(int fd, void *buf, size_t count)
13{
14 ssize_t n;
15
16 do {
17 n = read(fd, buf, count);
18 } while (n < 0 && errno == EINTR);
19
20 return n;
21}
22
23/*
24 * Read all of the supplied buffer from a file.
25 * This does multiple reads as necessary.
26 * Returns the amount read, or -1 on an error.
27 * A short read is returned on an end of file.
28 */
29ssize_t full_read(int fd, void *buf, size_t len)
30{
31 ssize_t cc;
32 ssize_t total;
33
34 total = 0;
35
36 while (len) {
37 cc = safe_read(fd, buf, len);
38
39 if (cc < 0)
40 return cc; /* read() returns -1 on failure. */
41
42 if (cc == 0)
43 break;
44
45 buf = ((char *)buf) + cc;
46 total += cc;
47 len -= cc;
48 }
49
50 return total;
51}
52
53// Die with an error message if we can't read the entire buffer.
54void xread(int fd, void *buf, size_t count)
55{
56 if (count) {
57 ssize_t size = full_read(fd, buf, count);
58 if (size != count)
59 bb_error_msg_and_die("short read");
60 }
61}
62
63// Die with an error message if we can't read one character.
64unsigned char xread_char(int fd)
65{
66 char tmp;
67
68 xread(fd, &tmp, 1);
69
70 return tmp;
71}
72
73// Read one line a-la fgets. Works only on seekable streams
74char *reads(int fd, char *buffer, size_t size)
75{
76 char *p;
77
78 if (size < 2)
79 return NULL;
80 size = full_read(fd, buffer, size-1);
81 if ((ssize_t)size <= 0)
82 return NULL;
83
84 buffer[size] = '\0';
85 p = strchr(buffer, '\n');
86 if (p) {
87 off_t offset;
88 *p++ = '\0';
89 offset = (p-buffer) - size;
90 // set fd position the right after the \n
91 if (offset && lseek(fd, offset, SEEK_CUR) == (off_t)-1)
92 return NULL;
93 }
94 return buffer;
95}
96
97ssize_t read_close(int fd, void *buf, size_t size)
98{
99 int e;
100 size = full_read(fd, buf, size);
101 e = errno;
102 close(fd);
103 errno = e;
104 return size;
105}
106
107ssize_t open_read_close(const char *filename, void *buf, size_t size)
108{
109 int fd = open(filename, O_RDONLY);
110 if (fd < 0)
111 return fd;
112 return read_close(fd, buf, size);
113}
114
115void *xmalloc_open_read_close(const char *filename, size_t *sizep)
116{
117 char *buf;
118 size_t size = sizep ? *sizep : INT_MAX;
119 int fd = xopen(filename, O_RDONLY);
120 off_t len = xlseek(fd, 0, SEEK_END);
121 xlseek(fd, 0, SEEK_SET);
122
123 if (len > size)
124 bb_error_msg_and_die("file '%s' is too big", filename);
125 size = len;
126 buf = xmalloc(size+1);
127 size = read_close(fd, buf, size);
128 if ((ssize_t)size < 0)
129 bb_perror_msg_and_die("'%s'", filename);
130 buf[size] = '\0';
131 if (sizep) *sizep = size;
132 return buf;
133}