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1 @c -*- mode: texinfo -*-
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2 @deftypefn Extension {struct pex_obj *} pex_init (int @var{flags}, const char *@var{pname}, const char *@var{tempbase})
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3
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4 Prepare to execute one or more programs, with standard output of each
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5 program fed to standard input of the next. This is a system
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6 independent interface to execute a pipeline.
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7
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8 @var{flags} is a bitwise combination of the following:
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9
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10 @table @code
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11
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12 @vindex PEX_RECORD_TIMES
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13 @item PEX_RECORD_TIMES
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14 Record subprocess times if possible.
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15
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16 @vindex PEX_USE_PIPES
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17 @item PEX_USE_PIPES
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18 Use pipes for communication between processes, if possible.
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19
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20 @vindex PEX_SAVE_TEMPS
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21 @item PEX_SAVE_TEMPS
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22 Don't delete temporary files used for communication between
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23 processes.
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24
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25 @end table
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26
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27 @var{pname} is the name of program to be executed, used in error
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28 messages. @var{tempbase} is a base name to use for any required
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29 temporary files; it may be @code{NULL} to use a randomly chosen name.
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30
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31 @end deftypefn
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32
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33 @deftypefn Extension {const char *} pex_run (struct pex_obj *@var{obj}, int @var{flags}, const char *@var{executable}, char * const *@var{argv}, const char *@var{outname}, const char *@var{errname}, int *@var{err})
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34
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35 Execute one program in a pipeline. On success this returns
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36 @code{NULL}. On failure it returns an error message, a statically
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37 allocated string.
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38
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39 @var{obj} is returned by a previous call to @code{pex_init}.
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40
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41 @var{flags} is a bitwise combination of the following:
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42
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43 @table @code
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44
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45 @vindex PEX_LAST
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46 @item PEX_LAST
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47 This must be set on the last program in the pipeline. In particular,
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48 it should be set when executing a single program. The standard output
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49 of the program will be sent to @var{outname}, or, if @var{outname} is
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50 @code{NULL}, to the standard output of the calling program. Do @emph{not}
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51 set this bit if you want to call @code{pex_read_output}
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52 (described below). After a call to @code{pex_run} with this bit set,
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53 @var{pex_run} may no longer be called with the same @var{obj}.
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54
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55 @vindex PEX_SEARCH
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56 @item PEX_SEARCH
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57 Search for the program using the user's executable search path.
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58
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59 @vindex PEX_SUFFIX
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60 @item PEX_SUFFIX
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61 @var{outname} is a suffix. See the description of @var{outname},
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62 below.
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63
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64 @vindex PEX_STDERR_TO_STDOUT
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65 @item PEX_STDERR_TO_STDOUT
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66 Send the program's standard error to standard output, if possible.
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67
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68 @vindex PEX_BINARY_INPUT
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69 @vindex PEX_BINARY_OUTPUT
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70 @vindex PEX_BINARY_ERROR
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71 @item PEX_BINARY_INPUT
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72 @itemx PEX_BINARY_OUTPUT
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73 @itemx PEX_BINARY_ERROR
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74 The standard input (output or error) of the program should be read (written) in
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75 binary mode rather than text mode. These flags are ignored on systems
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76 which do not distinguish binary mode and text mode, such as Unix. For
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77 proper behavior these flags should match appropriately---a call to
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78 @code{pex_run} using @code{PEX_BINARY_OUTPUT} should be followed by a
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79 call using @code{PEX_BINARY_INPUT}.
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80
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81 @vindex PEX_STDERR_TO_PIPE
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82 @item PEX_STDERR_TO_PIPE
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83 Send the program's standard error to a pipe, if possible. This flag
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84 cannot be specified together with @code{PEX_STDERR_TO_STDOUT}. This
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85 flag can be specified only on the last program in pipeline.
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86
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87 @end table
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88
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89 @var{executable} is the program to execute. @var{argv} is the set of
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90 arguments to pass to the program; normally @code{@var{argv}[0]} will
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91 be a copy of @var{executable}.
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92
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93 @var{outname} is used to set the name of the file to use for standard
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94 output. There are two cases in which no output file will be used:
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95
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96 @enumerate
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97 @item
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98 if @code{PEX_LAST} is not set in @var{flags}, and @code{PEX_USE_PIPES}
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99 was set in the call to @code{pex_init}, and the system supports pipes
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100
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101 @item
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102 if @code{PEX_LAST} is set in @var{flags}, and @var{outname} is
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103 @code{NULL}
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104 @end enumerate
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105
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106 @noindent
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107 Otherwise the code will use a file to hold standard
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108 output. If @code{PEX_LAST} is not set, this file is considered to be
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109 a temporary file, and it will be removed when no longer needed, unless
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110 @code{PEX_SAVE_TEMPS} was set in the call to @code{pex_init}.
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111
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112 There are two cases to consider when setting the name of the file to
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113 hold standard output.
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114
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115 @enumerate
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116 @item
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117 @code{PEX_SUFFIX} is set in @var{flags}. In this case
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118 @var{outname} may not be @code{NULL}. If the @var{tempbase} parameter
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119 to @code{pex_init} was not @code{NULL}, then the output file name is
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120 the concatenation of @var{tempbase} and @var{outname}. If
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121 @var{tempbase} was @code{NULL}, then the output file name is a random
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122 file name ending in @var{outname}.
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123
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124 @item
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125 @code{PEX_SUFFIX} was not set in @var{flags}. In this
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126 case, if @var{outname} is not @code{NULL}, it is used as the output
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127 file name. If @var{outname} is @code{NULL}, and @var{tempbase} was
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128 not NULL, the output file name is randomly chosen using
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129 @var{tempbase}. Otherwise the output file name is chosen completely
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130 at random.
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131 @end enumerate
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132
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133 @var{errname} is the file name to use for standard error output. If
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134 it is @code{NULL}, standard error is the same as the caller's.
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135 Otherwise, standard error is written to the named file.
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136
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137 On an error return, the code sets @code{*@var{err}} to an @code{errno}
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138 value, or to 0 if there is no relevant @code{errno}.
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139
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140 @end deftypefn
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141
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142 @deftypefn Extension {const char *} pex_run_in_environment (struct pex_obj *@var{obj}, int @var{flags}, const char *@var{executable}, char * const *@var{argv}, char * const *@var{env}, int @var{env_size}, const char *@var{outname}, const char *@var{errname}, int *@var{err})
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143
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144 Execute one program in a pipeline, permitting the environment for the
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145 program to be specified. Behaviour and parameters not listed below are
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146 as for @code{pex_run}.
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147
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148 @var{env} is the environment for the child process, specified as an array of
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149 character pointers. Each element of the array should point to a string of the
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150 form @code{VAR=VALUE}, with the exception of the last element that must be
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151 @code{NULL}.
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152
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153 @end deftypefn
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154
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155 @deftypefn Extension {FILE *} pex_input_file (struct pex_obj *@var{obj}, int @var{flags}, const char *@var{in_name})
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156
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157 Return a stream for a temporary file to pass to the first program in
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158 the pipeline as input.
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159
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160 The name of the input file is chosen according to the same rules
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161 @code{pex_run} uses to choose output file names, based on
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162 @var{in_name}, @var{obj} and the @code{PEX_SUFFIX} bit in @var{flags}.
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163
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164 Don't call @code{fclose} on the returned stream; the first call to
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165 @code{pex_run} closes it automatically.
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166
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167 If @var{flags} includes @code{PEX_BINARY_OUTPUT}, open the stream in
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168 binary mode; otherwise, open it in the default mode. Including
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169 @code{PEX_BINARY_OUTPUT} in @var{flags} has no effect on Unix.
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170 @end deftypefn
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171
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172 @deftypefn Extension {FILE *} pex_input_pipe (struct pex_obj *@var{obj}, int @var{binary})
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173
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174 Return a stream @var{fp} for a pipe connected to the standard input of
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175 the first program in the pipeline; @var{fp} is opened for writing.
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176 You must have passed @code{PEX_USE_PIPES} to the @code{pex_init} call
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177 that returned @var{obj}.
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178
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179 You must close @var{fp} using @code{fclose} yourself when you have
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180 finished writing data to the pipeline.
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181
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182 The file descriptor underlying @var{fp} is marked not to be inherited
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183 by child processes.
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184
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185 On systems that do not support pipes, this function returns
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186 @code{NULL}, and sets @code{errno} to @code{EINVAL}. If you would
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187 like to write code that is portable to all systems the @code{pex}
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188 functions support, consider using @code{pex_input_file} instead.
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189
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190 There are two opportunities for deadlock using
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191 @code{pex_input_pipe}:
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192
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193 @itemize @bullet
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194 @item
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195 Most systems' pipes can buffer only a fixed amount of data; a process
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196 that writes to a full pipe blocks. Thus, if you write to @file{fp}
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197 before starting the first process, you run the risk of blocking when
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198 there is no child process yet to read the data and allow you to
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199 continue. @code{pex_input_pipe} makes no promises about the
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200 size of the pipe's buffer, so if you need to write any data at all
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201 before starting the first process in the pipeline, consider using
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202 @code{pex_input_file} instead.
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203
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204 @item
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205 Using @code{pex_input_pipe} and @code{pex_read_output} together
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206 may also cause deadlock. If the output pipe fills up, so that each
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207 program in the pipeline is waiting for the next to read more data, and
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208 you fill the input pipe by writing more data to @var{fp}, then there
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209 is no way to make progress: the only process that could read data from
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210 the output pipe is you, but you are blocked on the input pipe.
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211
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212 @end itemize
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213
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214 @end deftypefn
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215
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216 @deftypefn Extension {FILE *} pex_read_output (struct pex_obj *@var{obj}, int @var{binary})
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217
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218 Returns a @code{FILE} pointer which may be used to read the standard
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219 output of the last program in the pipeline. When this is used,
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220 @code{PEX_LAST} should not be used in a call to @code{pex_run}. After
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221 this is called, @code{pex_run} may no longer be called with the same
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222 @var{obj}. @var{binary} should be non-zero if the file should be
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223 opened in binary mode. Don't call @code{fclose} on the returned file;
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224 it will be closed by @code{pex_free}.
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225
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226 @end deftypefn
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227
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228 @deftypefn Extension {FILE *} pex_read_err (struct pex_obj *@var{obj}, int @var{binary})
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229
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230 Returns a @code{FILE} pointer which may be used to read the standard
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231 error of the last program in the pipeline. When this is used,
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232 @code{PEX_LAST} should not be used in a call to @code{pex_run}. After
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233 this is called, @code{pex_run} may no longer be called with the same
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234 @var{obj}. @var{binary} should be non-zero if the file should be
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235 opened in binary mode. Don't call @code{fclose} on the returned file;
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236 it will be closed by @code{pex_free}.
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237
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238 @end deftypefn
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239
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240
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241 @deftypefn Extension int pex_get_status (struct pex_obj *@var{obj}, int @var{count}, int *@var{vector})
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242
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243 Returns the exit status of all programs run using @var{obj}.
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244 @var{count} is the number of results expected. The results will be
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245 placed into @var{vector}. The results are in the order of the calls
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246 to @code{pex_run}. Returns 0 on error, 1 on success.
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247
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248 @end deftypefn
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249
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250 @deftypefn Extension int pex_get_times (struct pex_obj *@var{obj}, int @var{count}, struct pex_time *@var{vector})
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251
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252 Returns the process execution times of all programs run using
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253 @var{obj}. @var{count} is the number of results expected. The
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254 results will be placed into @var{vector}. The results are in the
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255 order of the calls to @code{pex_run}. Returns 0 on error, 1 on
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256 success.
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257
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258 @code{struct pex_time} has the following fields of the type
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259 @code{unsigned long}: @code{user_seconds},
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260 @code{user_microseconds}, @code{system_seconds},
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261 @code{system_microseconds}. On systems which do not support reporting
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262 process times, all the fields will be set to @code{0}.
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263
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264 @end deftypefn
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265
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266 @deftypefn Extension void pex_free (struct pex_obj @var{obj})
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267
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268 Clean up and free all data associated with @var{obj}. If you have not
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269 yet called @code{pex_get_times} or @code{pex_get_status}, this will
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270 try to kill the subprocesses.
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271
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272 @end deftypefn
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273
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274 @deftypefn Extension {const char *} pex_one (int @var{flags}, const char *@var{executable}, char * const *@var{argv}, const char *@var{pname}, const char *@var{outname}, const char *@var{errname}, int *@var{status}, int *@var{err})
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275
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276 An interface to permit the easy execution of a
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277 single program. The return value and most of the parameters are as
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278 for a call to @code{pex_run}. @var{flags} is restricted to a
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279 combination of @code{PEX_SEARCH}, @code{PEX_STDERR_TO_STDOUT}, and
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280 @code{PEX_BINARY_OUTPUT}. @var{outname} is interpreted as if
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281 @code{PEX_LAST} were set. On a successful return, @code{*@var{status}} will
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282 be set to the exit status of the program.
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283
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284 @end deftypefn
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285
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286 @deftypefn Extension int pexecute (const char *@var{program}, char * const *@var{argv}, const char *@var{this_pname}, const char *@var{temp_base}, char **@var{errmsg_fmt}, char **@var{errmsg_arg}, int @var{flags})
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287
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288 This is the old interface to execute one or more programs. It is
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289 still supported for compatibility purposes, but is no longer
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290 documented.
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291
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292 @end deftypefn
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293
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294 @deftypefn Extension int pwait (int @var{pid}, int *@var{status}, int @var{flags})
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295
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296 Another part of the old execution interface.
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297
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298 @end deftypefn
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