| 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 |
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| 12 | /* Used by NOFORK applets (e.g. cat) - must not use xmalloc.
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| 13 | * size < 0 means "ignore write errors", used by tar --to-command
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| 14 | * size = 0 means "copy till EOF"
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| 15 | */
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| 16 | static off_t bb_full_fd_action(int src_fd, int dst_fd, off_t size)
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| 17 | {
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| 18 | int status = -1;
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| 19 | off_t total = 0;
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| 20 | bool continue_on_write_error = 0;
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| 21 | #if CONFIG_FEATURE_COPYBUF_KB <= 4
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| 22 | char buffer[CONFIG_FEATURE_COPYBUF_KB * 1024];
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| 23 | enum { buffer_size = sizeof(buffer) };
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| 24 | #else
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| 25 | char *buffer;
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| 26 | int buffer_size;
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| 27 | #endif
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| 28 |
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| 29 | if (size < 0) {
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| 30 | size = -size;
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| 31 | continue_on_write_error = 1;
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| 32 | }
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| 33 |
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| 34 | #if CONFIG_FEATURE_COPYBUF_KB > 4
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| 35 | if (size > 0 && size <= 4 * 1024)
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| 36 | goto use_small_buf;
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| 37 | /* We want page-aligned buffer, just in case kernel is clever
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| 38 | * and can do page-aligned io more efficiently */
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| 39 | buffer = mmap(NULL, CONFIG_FEATURE_COPYBUF_KB * 1024,
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| 40 | PROT_READ | PROT_WRITE,
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| 41 | MAP_PRIVATE | MAP_ANON,
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| 42 | /* ignored: */ -1, 0);
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| 43 | buffer_size = CONFIG_FEATURE_COPYBUF_KB * 1024;
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| 44 | if (buffer == MAP_FAILED) {
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| 45 | use_small_buf:
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| 46 | buffer = alloca(4 * 1024);
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| 47 | buffer_size = 4 * 1024;
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| 48 | }
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| 49 | #endif
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| 50 |
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| 51 | if (src_fd < 0)
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| 52 | goto out;
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| 53 |
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| 54 | if (!size) {
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| 55 | size = buffer_size;
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| 56 | status = 1; /* copy until eof */
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| 57 | }
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| 58 |
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| 59 | while (1) {
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| 60 | ssize_t rd;
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| 61 |
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| 62 | rd = safe_read(src_fd, buffer, size > buffer_size ? buffer_size : size);
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| 63 |
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| 64 | if (!rd) { /* eof - all done */
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| 65 | status = 0;
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| 66 | break;
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| 67 | }
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| 68 | if (rd < 0) {
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| 69 | bb_perror_msg(bb_msg_read_error);
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| 70 | break;
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| 71 | }
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| 72 | /* dst_fd == -1 is a fake, else... */
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| 73 | if (dst_fd >= 0) {
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| 74 | ssize_t wr = full_write(dst_fd, buffer, rd);
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| 75 | if (wr < rd) {
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| 76 | if (!continue_on_write_error) {
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| 77 | bb_perror_msg(bb_msg_write_error);
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| 78 | break;
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| 79 | }
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| 80 | dst_fd = -1;
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| 81 | }
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| 82 | }
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| 83 | total += rd;
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| 84 | if (status < 0) { /* if we aren't copying till EOF... */
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| 85 | size -= rd;
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| 86 | if (!size) {
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| 87 | /* 'size' bytes copied - all done */
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| 88 | status = 0;
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| 89 | break;
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| 90 | }
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| 91 | }
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| 92 | }
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| 93 | out:
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| 94 |
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| 95 | #if CONFIG_FEATURE_COPYBUF_KB > 4
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| 96 | if (buffer_size != 4 * 1024)
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| 97 | munmap(buffer, buffer_size);
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| 98 | #endif
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| 99 | return status ? -1 : total;
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| 100 | }
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| 101 |
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| 102 |
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| 103 | #if 0
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| 104 | void FAST_FUNC complain_copyfd_and_die(off_t sz)
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| 105 | {
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| 106 | if (sz != -1)
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| 107 | bb_error_msg_and_die("short read");
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| 108 | /* if sz == -1, bb_copyfd_XX already complained */
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| 109 | xfunc_die();
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| 110 | }
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| 111 | #endif
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| 112 |
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| 113 | off_t FAST_FUNC bb_copyfd_size(int fd1, int fd2, off_t size)
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| 114 | {
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| 115 | if (size) {
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| 116 | return bb_full_fd_action(fd1, fd2, size);
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| 117 | }
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| 118 | return 0;
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| 119 | }
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| 120 |
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| 121 | void FAST_FUNC bb_copyfd_exact_size(int fd1, int fd2, off_t size)
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| 122 | {
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| 123 | off_t sz = bb_copyfd_size(fd1, fd2, size);
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| 124 | if (sz == (size >= 0 ? size : -size))
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| 125 | return;
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| 126 | if (sz != -1)
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| 127 | bb_error_msg_and_die("short read");
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| 128 | /* if sz == -1, bb_copyfd_XX already complained */
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| 129 | xfunc_die();
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| 130 | }
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| 131 |
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| 132 | off_t FAST_FUNC bb_copyfd_eof(int fd1, int fd2)
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| 133 | {
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| 134 | return bb_full_fd_action(fd1, fd2, 0);
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| 135 | }
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