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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