1 | <?xml version="1.0" encoding="ISO-8859-1"?> |
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
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3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [ |
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4 | <!ENTITY % general-entities SYSTEM "../../general.ent"> |
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5 | %general-entities; |
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6 | ]> |
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7 | |
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8 | <sect1 id="ch-system-multiarch-wrapper" role="wrap"> |
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9 | <?dbhtml filename="multiarch_wrapper.html"?> |
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10 | |
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11 | <title>Creating a Multiarch Wrapper</title> |
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12 | |
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13 | <indexterm zone="ch-system-multiarch-wrapper"> |
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14 | <primary sortas="a-Multiarch Wrapper">Multiarch Wrapper</primary> |
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15 | </indexterm> |
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16 | |
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17 | <sect2 role="package"> |
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18 | <title/> |
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19 | |
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20 | <para>The Multiarch Wrapper is used to wrap certain binaries that have |
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21 | hardcoded paths to libraries or are architecture specific.</para> |
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22 | |
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23 | </sect2> |
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24 | |
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25 | <sect2 role="installation"> |
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26 | <title>Installation of The Multiarch Wrapper</title> |
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27 | |
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28 | <para os="a">Create the source file:</para> |
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29 | |
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30 | <screen os="b"><userinput>cat > multiarch_wrapper.c << "EOF" |
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31 | #define _GNU_SOURCE |
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32 | |
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33 | #include <errno.h> |
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34 | #include <stdio.h> |
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35 | #include <stdlib.h> |
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36 | #include <sys/types.h> |
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37 | #include <sys/wait.h> |
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38 | #include <unistd.h> |
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39 | |
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40 | #ifndef DEF_SUFFIX |
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41 | # define DEF_SUFFIX "64" |
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42 | #endif |
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43 | |
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44 | int main(int argc, char **argv) |
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45 | { |
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46 | char *filename; |
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47 | char *suffix; |
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48 | |
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49 | if(!(suffix = getenv("USE_ARCH"))) |
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50 | if(!(suffix = getenv("BUILDENV"))) |
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51 | suffix = DEF_SUFFIX; |
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52 | |
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53 | if (asprintf(&filename, "%s-%s", argv[0], suffix) < 0) { |
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54 | perror(argv[0]); |
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55 | return -1; |
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56 | } |
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57 | |
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58 | int status = EXIT_FAILURE; |
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59 | pid_t pid = fork(); |
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60 | |
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61 | if (pid == 0) { |
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62 | execvp(filename, argv); |
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63 | perror(filename); |
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64 | } else if (pid < 0) { |
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65 | perror(argv[0]); |
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66 | } else { |
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67 | if (waitpid(pid, &status, 0) != pid) { |
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68 | status = EXIT_FAILURE; |
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69 | perror(argv[0]); |
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70 | } else { |
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71 | status = WEXITSTATUS(status); |
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72 | } |
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73 | } |
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74 | |
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75 | free(filename); |
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76 | |
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77 | return status; |
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78 | } |
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79 | |
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80 | EOF</userinput></screen> |
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81 | |
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82 | <para os="c">Compile and Install the Multiarch Wrapper:</para> |
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83 | |
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84 | <screen os="d"><userinput>gcc ${BUILD64} multiarch_wrapper.c -o /usr/bin/multiarch_wrapper</userinput></screen> |
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85 | |
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86 | <para os="e">This multiarch wrapper is going to be used later on in the book |
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87 | with Perl. It will also be very useful outside of the base CLFS system.</para> |
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88 | |
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89 | <para os="f">Create a testcase:</para> |
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90 | |
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91 | <screen os="g"><userinput>echo 'echo "32bit Version"' > test-32 |
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92 | echo 'echo "64bit Version"' > test-64 |
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93 | chmod -v 755 test-32 test-64 |
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94 | ln -sv /usr/bin/multiarch_wrapper test</userinput></screen> |
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95 | |
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96 | <para os="h">Test the wrapper:</para> |
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97 | |
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98 | <screen os="i"><userinput>USE_ARCH=32 ./test |
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99 | USE_ARCH=64 ./test</userinput></screen> |
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100 | |
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101 | <para os="j">The output of the above command should be:</para> |
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102 | |
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103 | <screen os="k" role="nodump"><userinput>32bit Version |
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104 | 64bit Version</userinput></screen> |
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105 | |
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106 | <para os="l">Remove the testcase source, binaries, and link:</para> |
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107 | |
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108 | <screen os="m"><userinput>rm -v multiarch_wrapper.c test{,-32,-64}</userinput></screen> |
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109 | |
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110 | </sect2> |
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111 | |
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112 | <sect2 id="contents-multiarch-wrapper" role="content"> |
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113 | <title>Contents of The Multiarch Wrapper</title> |
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114 | |
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115 | <segmentedlist> |
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116 | <segtitle>Installed programs</segtitle> |
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117 | |
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118 | <seglistitem> |
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119 | <seg>multiarch_wrapper</seg> |
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120 | </seglistitem> |
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121 | </segmentedlist> |
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122 | |
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123 | <variablelist> |
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124 | <bridgehead renderas="sect3">Short Descriptions</bridgehead> |
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125 | <?dbfo list-presentation="list"?> |
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126 | <?dbhtml list-presentation="table"?> |
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127 | |
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128 | <varlistentry id="multiarch_wrapper"> |
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129 | <term><command>multiarch_wrapper</command></term> |
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130 | <listitem> |
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131 | <para>Will execute a different program based on the |
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132 | <envar>USE_ARCH</envar> variable. The <envar>USE_ARCH</envar> |
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133 | variable will be the suffix of the executed program.</para> |
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134 | <indexterm zone="ch-system-multiarch-wrapper multiarch_wrapper"> |
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135 | <primary sortas="b-multiarch_wrapper">multiarch_wrapper</primary> |
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136 | </indexterm> |
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137 | </listitem> |
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138 | </varlistentry> |
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139 | |
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140 | </variablelist> |
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141 | |
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142 | </sect2> |
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143 | |
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144 | </sect1> |
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