1 /* 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 source tree.
8 */
9 #include "libbb.h"
10
safe_read(int fd,void * buf,size_t count)11 ssize_t FAST_FUNC safe_read(int fd, void *buf, size_t count)
12 {
13 ssize_t n;
14
15 for (;;) {
16 n = read(fd, buf, count);
17 if (n >= 0 || errno != EINTR)
18 break;
19 /* Some callers set errno=0, are upset when they see EINTR.
20 * Returning EINTR is wrong since we retry read(),
21 * the "error" was transient.
22 */
23 errno = 0;
24 /* repeat the read() */
25 }
26
27 return n;
28 }
29
30 /*
31 * Read all of the supplied buffer from a file.
32 * This does multiple reads as necessary.
33 * Returns the amount read, or -1 on an error.
34 * A short read is returned on an end of file.
35 */
full_read(int fd,void * buf,size_t len)36 ssize_t FAST_FUNC full_read(int fd, void *buf, size_t len)
37 {
38 ssize_t cc;
39 ssize_t total;
40
41 total = 0;
42
43 while (len) {
44 cc = safe_read(fd, buf, len);
45
46 if (cc < 0) {
47 if (total) {
48 /* we already have some! */
49 /* user can do another read to know the error code */
50 return total;
51 }
52 return cc; /* read() returns -1 on failure. */
53 }
54 if (cc == 0)
55 break;
56 buf = ((char *)buf) + cc;
57 total += cc;
58 len -= cc;
59 }
60
61 return total;
62 }
63
read_close(int fd,void * buf,size_t size)64 ssize_t FAST_FUNC read_close(int fd, void *buf, size_t size)
65 {
66 /*int e;*/
67 size = full_read(fd, buf, size);
68 /*e = errno;*/
69 close(fd);
70 /*errno = e;*/
71 return size;
72 }
73
open_read_close(const char * filename,void * buf,size_t size)74 ssize_t FAST_FUNC open_read_close(const char *filename, void *buf, size_t size)
75 {
76 int fd = open(filename, O_RDONLY);
77 if (fd < 0)
78 return fd;
79 return read_close(fd, buf, size);
80 }
81