| 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Utility routines.
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| 4 | *
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| 5 | * Copyright (C) 1999-2005 by Erik Andersen <andersen@codepoet.org>
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| 6 | *
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| 7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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| 8 | */
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| 9 |
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| 10 | #include "libbb.h"
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| 11 | #if ENABLE_FEATURE_USE_SENDFILE
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| 12 | # include <sys/sendfile.h>
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| 13 | #else
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| 14 | # define sendfile(a,b,c,d) (-1)
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| 15 | #endif
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| 16 |
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| 17 | /*
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| 18 | * We were using 0x7fff0000 as sendfile chunk size, but it
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| 19 | * was seen to cause largish delays when user tries to ^C a file copy.
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| 20 | * Let's use a saner size.
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| 21 | * Note: needs to be >= max(CONFIG_FEATURE_COPYBUF_KB),
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| 22 | * or else "copy to eof" code will use neddlesly short reads.
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| 23 | */
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| 24 | #define SENDFILE_BIGBUF (16*1024*1024)
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| 25 |
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| 26 | /* Used by NOFORK applets (e.g. cat) - must not use xmalloc.
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| 27 | * size < 0 means "ignore write errors", used by tar --to-command
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| 28 | * size = 0 means "copy till EOF"
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| 29 | */
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| 30 | static off_t bb_full_fd_action(int src_fd, int dst_fd, off_t size)
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| 31 | {
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| 32 | int status = -1;
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| 33 | off_t total = 0;
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| 34 | bool continue_on_write_error = 0;
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| 35 | ssize_t sendfile_sz;
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| 36 | #if CONFIG_FEATURE_COPYBUF_KB > 4
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| 37 | char *buffer = buffer; /* for compiler */
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| 38 | int buffer_size = 0;
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| 39 | #else
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| 40 | char buffer[CONFIG_FEATURE_COPYBUF_KB * 1024];
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| 41 | enum { buffer_size = sizeof(buffer) };
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| 42 | #endif
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| 43 |
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| 44 | if (size < 0) {
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| 45 | size = -size;
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| 46 | continue_on_write_error = 1;
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| 47 | }
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| 48 |
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| 49 | if (src_fd < 0)
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| 50 | goto out;
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| 51 |
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| 52 | sendfile_sz = !ENABLE_FEATURE_USE_SENDFILE
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| 53 | ? 0
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| 54 | : SENDFILE_BIGBUF;
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| 55 | if (!size) {
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| 56 | size = SENDFILE_BIGBUF;
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| 57 | status = 1; /* copy until eof */
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| 58 | }
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| 59 |
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| 60 | while (1) {
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| 61 | ssize_t rd;
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| 62 |
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| 63 | if (sendfile_sz) {
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| 64 | rd = sendfile(dst_fd, src_fd, NULL,
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| 65 | size > sendfile_sz ? sendfile_sz : size);
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| 66 | if (rd >= 0)
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| 67 | goto read_ok;
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| 68 | sendfile_sz = 0; /* do not try sendfile anymore */
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| 69 | }
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| 70 | #if CONFIG_FEATURE_COPYBUF_KB > 4
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| 71 | if (buffer_size == 0) {
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| 72 | if (size > 0 && size <= 4 * 1024)
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| 73 | goto use_small_buf;
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| 74 | /* We want page-aligned buffer, just in case kernel is clever
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| 75 | * and can do page-aligned io more efficiently */
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| 76 | buffer = mmap(NULL, CONFIG_FEATURE_COPYBUF_KB * 1024,
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| 77 | PROT_READ | PROT_WRITE,
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| 78 | MAP_PRIVATE | MAP_ANON,
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| 79 | /* ignored: */ -1, 0);
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| 80 | buffer_size = CONFIG_FEATURE_COPYBUF_KB * 1024;
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| 81 | if (buffer == MAP_FAILED) {
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| 82 | use_small_buf:
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| 83 | buffer = alloca(4 * 1024);
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| 84 | buffer_size = 4 * 1024;
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| 85 | }
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| 86 | }
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| 87 | #endif
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| 88 | rd = safe_read(src_fd, buffer,
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| 89 | size > buffer_size ? buffer_size : size);
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| 90 | if (rd < 0) {
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| 91 | bb_perror_msg(bb_msg_read_error);
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| 92 | break;
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| 93 | }
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| 94 | read_ok:
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| 95 | if (!rd) { /* eof - all done */
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| 96 | status = 0;
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| 97 | break;
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| 98 | }
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| 99 | /* dst_fd == -1 is a fake, else... */
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| 100 | if (dst_fd >= 0 && !sendfile_sz) {
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| 101 | ssize_t wr = full_write(dst_fd, buffer, rd);
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| 102 | if (wr < rd) {
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| 103 | if (!continue_on_write_error) {
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| 104 | bb_perror_msg(bb_msg_write_error);
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| 105 | break;
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| 106 | }
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| 107 | dst_fd = -1;
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| 108 | }
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| 109 | }
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| 110 | total += rd;
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| 111 | if (status < 0) { /* if we aren't copying till EOF... */
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| 112 | size -= rd;
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| 113 | if (!size) {
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| 114 | /* 'size' bytes copied - all done */
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| 115 | status = 0;
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| 116 | break;
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| 117 | }
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| 118 | }
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| 119 | }
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| 120 | out:
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| 121 |
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| 122 | if (buffer_size > 4 * 1024)
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| 123 | munmap(buffer, buffer_size);
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| 124 | return status ? -1 : total;
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| 125 | }
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| 126 |
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| 127 |
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| 128 | #if 0
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| 129 | void FAST_FUNC complain_copyfd_and_die(off_t sz)
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| 130 | {
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| 131 | if (sz != -1)
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| 132 | bb_error_msg_and_die("short read");
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| 133 | /* if sz == -1, bb_copyfd_XX already complained */
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| 134 | xfunc_die();
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| 135 | }
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| 136 | #endif
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| 137 |
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| 138 | off_t FAST_FUNC bb_copyfd_size(int fd1, int fd2, off_t size)
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| 139 | {
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| 140 | if (size) {
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| 141 | return bb_full_fd_action(fd1, fd2, size);
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| 142 | }
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| 143 | return 0;
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| 144 | }
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| 145 |
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| 146 | void FAST_FUNC bb_copyfd_exact_size(int fd1, int fd2, off_t size)
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| 147 | {
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| 148 | off_t sz = bb_copyfd_size(fd1, fd2, size);
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| 149 | if (sz == (size >= 0 ? size : -size))
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| 150 | return;
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| 151 | if (sz != -1)
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| 152 | bb_error_msg_and_die("short read");
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| 153 | /* if sz == -1, bb_copyfd_XX already complained */
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| 154 | xfunc_die();
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| 155 | }
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| 156 |
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| 157 | off_t FAST_FUNC bb_copyfd_eof(int fd1, int fd2)
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| 158 | {
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| 159 | return bb_full_fd_action(fd1, fd2, 0);
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| 160 | }
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