1 /* vi: set sw=4 ts=4: */
2 /*
3 * Utility routines.
4 *
5 * Copyright (C) 1999-2005 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 #if ENABLE_FEATURE_USE_SENDFILE
11 # include <sys/sendfile.h>
12 #else
13 # define sendfile(a,b,c,d) (-1)
14 #endif
15
16 /*
17 * We were using 0x7fff0000 as sendfile chunk size, but it
18 * was seen to cause largish delays when user tries to ^C a file copy.
19 * Let's use a saner size.
20 * Note: needs to be >= max(CONFIG_FEATURE_COPYBUF_KB),
21 * or else "copy to eof" code will use needlesly short reads.
22 */
23 #define SENDFILE_BIGBUF (16*1024*1024)
24
25 /* Used by NOFORK applets (e.g. cat) - must not use xmalloc.
26 * size < 0 means "ignore write errors", used by tar --to-command
27 * size = 0 means "copy till EOF"
28 */
bb_full_fd_action(int src_fd,int dst_fd,off_t size)29 static off_t bb_full_fd_action(int src_fd, int dst_fd, off_t size)
30 {
31 int status = -1;
32 off_t total = 0;
33 bool continue_on_write_error = 0;
34 ssize_t sendfile_sz;
35 #if CONFIG_FEATURE_COPYBUF_KB > 4
36 char *buffer = buffer; /* for compiler */
37 int buffer_size = 0;
38 #else
39 char buffer[CONFIG_FEATURE_COPYBUF_KB * 1024];
40 enum { buffer_size = sizeof(buffer) };
41 #endif
42
43 if (size < 0) {
44 size = -size;
45 continue_on_write_error = 1;
46 }
47
48 if (src_fd < 0)
49 goto out;
50
51 sendfile_sz = !ENABLE_FEATURE_USE_SENDFILE
52 ? 0
53 : SENDFILE_BIGBUF;
54 if (!size) {
55 size = SENDFILE_BIGBUF;
56 status = 1; /* copy until eof */
57 }
58
59 while (1) {
60 ssize_t rd;
61
62 if (sendfile_sz) {
63 /* dst_fd == -1 is a fake, else... */
64 if (dst_fd >= 0) {
65 rd = sendfile(dst_fd, src_fd, NULL,
66 size > sendfile_sz ? sendfile_sz : size);
67 if (rd >= 0)
68 goto read_ok;
69 }
70 sendfile_sz = 0; /* do not try sendfile anymore */
71 }
72 #if CONFIG_FEATURE_COPYBUF_KB > 4
73 if (buffer_size == 0) {
74 if (size > 0 && size <= 4 * 1024)
75 goto use_small_buf;
76 /* We want page-aligned buffer, just in case kernel is clever
77 * and can do page-aligned io more efficiently */
78 buffer = mmap_anon(CONFIG_FEATURE_COPYBUF_KB * 1024);
79 buffer_size = CONFIG_FEATURE_COPYBUF_KB * 1024;
80 if (buffer == MAP_FAILED) {
81 use_small_buf:
82 buffer = alloca(4 * 1024);
83 buffer_size = 4 * 1024;
84 }
85 }
86 #endif
87 rd = safe_read(src_fd, buffer,
88 size > buffer_size ? buffer_size : size);
89 if (rd < 0) {
90 bb_simple_perror_msg(bb_msg_read_error);
91 break;
92 }
93 read_ok:
94 if (!rd) { /* eof - all done */
95 status = 0;
96 break;
97 }
98 /* dst_fd == -1 is a fake, else... */
99 if (dst_fd >= 0 && !sendfile_sz) {
100 ssize_t wr = full_write(dst_fd, buffer, rd);
101 if (wr < rd) {
102 if (!continue_on_write_error) {
103 bb_simple_perror_msg(bb_msg_write_error);
104 break;
105 }
106 dst_fd = -1;
107 }
108 }
109 total += rd;
110 if (status < 0) { /* if we aren't copying till EOF... */
111 size -= rd;
112 if (!size) {
113 /* 'size' bytes copied - all done */
114 status = 0;
115 break;
116 }
117 }
118 }
119 out:
120
121 /* some environments don't have munmap(), hide it in #if */
122 #if CONFIG_FEATURE_COPYBUF_KB > 4
123 if (buffer_size > 4 * 1024)
124 munmap(buffer, buffer_size);
125 #endif
126 return status ? -1 : total;
127 }
128
129
130 #if 0
131 void FAST_FUNC complain_copyfd_and_die(off_t sz)
132 {
133 if (sz != -1)
134 bb_error_msg_and_die("short read");
135 /* if sz == -1, bb_copyfd_XX already complained */
136 xfunc_die();
137 }
138 #endif
139
bb_copyfd_size(int fd1,int fd2,off_t size)140 off_t FAST_FUNC bb_copyfd_size(int fd1, int fd2, off_t size)
141 {
142 if (size) {
143 return bb_full_fd_action(fd1, fd2, size);
144 }
145 return 0;
146 }
147
bb_copyfd_exact_size(int fd1,int fd2,off_t size)148 void FAST_FUNC bb_copyfd_exact_size(int fd1, int fd2, off_t size)
149 {
150 off_t sz = bb_copyfd_size(fd1, fd2, size);
151 if (sz == (size >= 0 ? size : -size))
152 return;
153 if (sz != -1)
154 bb_simple_error_msg_and_die("short read");
155 /* if sz == -1, bb_copyfd_XX already complained */
156 xfunc_die();
157 }
158
bb_copyfd_eof(int fd1,int fd2)159 off_t FAST_FUNC bb_copyfd_eof(int fd1, int fd2)
160 {
161 return bb_full_fd_action(fd1, fd2, 0);
162 }
163