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3db2e6dd | 1 | @c -*- mode: texinfo -*- |
f13c9bea | 2 | @deftypefn Extension {struct pex_obj *} pex_init (int @var{flags}, const char *@var{pname}, const char *@var{tempbase}) |
5a17353c | 3 | |
b109e79a ILT |
4 | Prepare to execute one or more programs, with standard output of each |
5 | program fed to standard input of the next. This is a system | |
6 | independent interface to execute a pipeline. | |
5a17353c | 7 | |
b109e79a | 8 | @var{flags} is a bitwise combination of the following: |
5a17353c | 9 | |
b109e79a | 10 | @table @code |
5a17353c | 11 | |
b109e79a ILT |
12 | @vindex PEX_RECORD_TIMES |
13 | @item PEX_RECORD_TIMES | |
14 | Record subprocess times if possible. | |
5a17353c | 15 | |
b109e79a ILT |
16 | @vindex PEX_USE_PIPES |
17 | @item PEX_USE_PIPES | |
18 | Use pipes for communication between processes, if possible. | |
5a17353c | 19 | |
b109e79a ILT |
20 | @vindex PEX_SAVE_TEMPS |
21 | @item PEX_SAVE_TEMPS | |
22 | Don't delete temporary files used for communication between | |
23 | processes. | |
5a17353c | 24 | |
b109e79a | 25 | @end table |
5a17353c | 26 | |
b109e79a ILT |
27 | @var{pname} is the name of program to be executed, used in error |
28 | messages. @var{tempbase} is a base name to use for any required | |
29 | temporary files; it may be @code{NULL} to use a randomly chosen name. | |
5a17353c DD |
30 | |
31 | @end deftypefn | |
32 | ||
f13c9bea | 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}) |
b109e79a ILT |
34 | |
35 | Execute one program in a pipeline. On success this returns | |
36 | @code{NULL}. On failure it returns an error message, a statically | |
37 | allocated string. | |
38 | ||
39 | @var{obj} is returned by a previous call to @code{pex_init}. | |
40 | ||
41 | @var{flags} is a bitwise combination of the following: | |
42 | ||
43 | @table @code | |
44 | ||
45 | @vindex PEX_LAST | |
46 | @item PEX_LAST | |
47 | This must be set on the last program in the pipeline. In particular, | |
48 | it should be set when executing a single program. The standard output | |
49 | of the program will be sent to @var{outname}, or, if @var{outname} is | |
f13c9bea DD |
50 | @code{NULL}, to the standard output of the calling program. Do @emph{not} |
51 | set this bit if you want to call @code{pex_read_output} | |
b109e79a ILT |
52 | (described below). After a call to @code{pex_run} with this bit set, |
53 | @var{pex_run} may no longer be called with the same @var{obj}. | |
54 | ||
55 | @vindex PEX_SEARCH | |
56 | @item PEX_SEARCH | |
57 | Search for the program using the user's executable search path. | |
58 | ||
59 | @vindex PEX_SUFFIX | |
60 | @item PEX_SUFFIX | |
61 | @var{outname} is a suffix. See the description of @var{outname}, | |
62 | below. | |
63 | ||
64 | @vindex PEX_STDERR_TO_STDOUT | |
65 | @item PEX_STDERR_TO_STDOUT | |
66 | Send the program's standard error to standard output, if possible. | |
67 | ||
68 | @vindex PEX_BINARY_INPUT | |
69 | @vindex PEX_BINARY_OUTPUT | |
70 | @item PEX_BINARY_INPUT | |
71 | @itemx PEX_BINARY_OUTPUT | |
72 | The standard input (output) of the program should be read (written) in | |
73 | binary mode rather than text mode. These flags are ignored on systems | |
74 | which do not distinguish binary mode and text mode, such as Unix. For | |
f13c9bea | 75 | proper behavior these flags should match appropriately---a call to |
b109e79a ILT |
76 | @code{pex_run} using @code{PEX_BINARY_OUTPUT} should be followed by a |
77 | call using @code{PEX_BINARY_INPUT}. | |
78 | @end table | |
79 | ||
80 | @var{executable} is the program to execute. @var{argv} is the set of | |
81 | arguments to pass to the program; normally @code{@var{argv}[0]} will | |
82 | be a copy of @var{executable}. | |
83 | ||
84 | @var{outname} is used to set the name of the file to use for standard | |
f13c9bea DD |
85 | output. There are two cases in which no output file will be used: |
86 | ||
87 | @enumerate | |
88 | @item | |
b109e79a | 89 | if @code{PEX_LAST} is not set in @var{flags}, and @code{PEX_USE_PIPES} |
f13c9bea DD |
90 | was set in the call to @code{pex_init}, and the system supports pipes |
91 | ||
92 | @item | |
93 | if @code{PEX_LAST} is set in @var{flags}, and @var{outname} is | |
94 | @code{NULL} | |
95 | @end enumerate | |
96 | ||
97 | @noindent | |
98 | Otherwise the code will use a file to hold standard | |
b109e79a ILT |
99 | output. If @code{PEX_LAST} is not set, this file is considered to be |
100 | a temporary file, and it will be removed when no longer needed, unless | |
101 | @code{PEX_SAVE_TEMPS} was set in the call to @code{pex_init}. | |
102 | ||
103 | There are two cases to consider when setting the name of the file to | |
104 | hold standard output. | |
105 | ||
f13c9bea DD |
106 | @enumerate |
107 | @item | |
108 | @code{PEX_SUFFIX} is set in @var{flags}. In this case | |
b109e79a ILT |
109 | @var{outname} may not be @code{NULL}. If the @var{tempbase} parameter |
110 | to @code{pex_init} was not @code{NULL}, then the output file name is | |
111 | the concatenation of @var{tempbase} and @var{outname}. If | |
112 | @var{tempbase} was @code{NULL}, then the output file name is a random | |
113 | file name ending in @var{outname}. | |
114 | ||
f13c9bea DD |
115 | @item |
116 | @code{PEX_SUFFIX} was not set in @var{flags}. In this | |
b109e79a ILT |
117 | case, if @var{outname} is not @code{NULL}, it is used as the output |
118 | file name. If @var{outname} is @code{NULL}, and @var{tempbase} was | |
119 | not NULL, the output file name is randomly chosen using | |
120 | @var{tempbase}. Otherwise the output file name is chosen completely | |
121 | at random. | |
f13c9bea | 122 | @end enumerate |
b109e79a ILT |
123 | |
124 | @var{errname} is the file name to use for standard error output. If | |
f13c9bea | 125 | it is @code{NULL}, standard error is the same as the caller's. |
b109e79a ILT |
126 | Otherwise, standard error is written to the named file. |
127 | ||
128 | On an error return, the code sets @code{*@var{err}} to an @code{errno} | |
129 | value, or to 0 if there is no relevant @code{errno}. | |
130 | ||
131 | @end deftypefn | |
132 | ||
3db2e6dd DD |
133 | @deftypefn Extension {FILE *} pex_input_file (struct pex_obj *@var{obj}, int @var{flags}, const char *@var{in_name}) |
134 | ||
135 | Return a stream for a temporary file to pass to the first program in | |
136 | the pipeline as input. | |
137 | ||
138 | The name of the input file is chosen according to the same rules | |
139 | @code{pex_run} uses to choose output file names, based on | |
140 | @var{in_name}, @var{obj} and the @code{PEX_SUFFIX} bit in @var{flags}. | |
141 | ||
142 | Don't call @code{fclose} on the returned stream; the first call to | |
143 | @code{pex_run} closes it automatically. | |
144 | ||
145 | If @var{flags} includes @code{PEX_BINARY_OUTPUT}, open the stream in | |
146 | binary mode; otherwise, open it in the default mode. Including | |
147 | @code{PEX_BINARY_OUTPUT} in @var{flags} has no effect on Unix. | |
148 | @end deftypefn | |
149 | ||
150 | @deftypefn Extension {FILE *} pex_input_pipe (struct pex_obj *@var{obj}, int @var{binary}) | |
151 | ||
152 | Return a stream @var{fp} for a pipe connected to the standard input of | |
153 | the first program in the pipeline; @var{fp} is opened for writing. | |
154 | You must have passed @code{PEX_USE_PIPES} to the @code{pex_init} call | |
155 | that returned @var{obj}. | |
156 | ||
157 | You must close @var{fp} using @code{fclose} yourself when you have | |
158 | finished writing data to the pipeline. | |
159 | ||
160 | The file descriptor underlying @var{fp} is marked not to be inherited | |
161 | by child processes. | |
162 | ||
163 | On systems that do not support pipes, this function returns | |
164 | @code{NULL}, and sets @code{errno} to @code{EINVAL}. If you would | |
165 | like to write code that is portable to all systems the @code{pex} | |
166 | functions support, consider using @code{pex_input_file} instead. | |
167 | ||
168 | There are two opportunities for deadlock using | |
169 | @code{pex_input_pipe}: | |
170 | ||
171 | @itemize @bullet | |
172 | @item | |
173 | Most systems' pipes can buffer only a fixed amount of data; a process | |
174 | that writes to a full pipe blocks. Thus, if you write to @file{fp} | |
175 | before starting the first process, you run the risk of blocking when | |
176 | there is no child process yet to read the data and allow you to | |
177 | continue. @code{pex_input_pipe} makes no promises about the | |
178 | size of the pipe's buffer, so if you need to write any data at all | |
179 | before starting the first process in the pipeline, consider using | |
180 | @code{pex_input_file} instead. | |
181 | ||
182 | @item | |
183 | Using @code{pex_input_pipe} and @code{pex_read_output} together | |
184 | may also cause deadlock. If the output pipe fills up, so that each | |
185 | program in the pipeline is waiting for the next to read more data, and | |
186 | you fill the input pipe by writing more data to @var{fp}, then there | |
187 | is no way to make progress: the only process that could read data from | |
188 | the output pipe is you, but you are blocked on the input pipe. | |
189 | ||
190 | @end itemize | |
191 | ||
192 | @end deftypefn | |
193 | ||
f13c9bea | 194 | @deftypefn Extension {FILE *} pex_read_output (struct pex_obj *@var{obj}, int @var{binary}) |
b109e79a ILT |
195 | |
196 | Returns a @code{FILE} pointer which may be used to read the standard | |
197 | output of the last program in the pipeline. When this is used, | |
198 | @code{PEX_LAST} should not be used in a call to @code{pex_run}. After | |
199 | this is called, @code{pex_run} may no longer be called with the same | |
200 | @var{obj}. @var{binary} should be non-zero if the file should be | |
201 | opened in binary mode. Don't call @code{fclose} on the returned file; | |
202 | it will be closed by @code{pex_free}. | |
203 | ||
204 | @end deftypefn | |
205 | ||
206 | @deftypefn Extension int pex_get_status (struct pex_obj *@var{obj}, int @var{count}, int *@var{vector}) | |
207 | ||
208 | Returns the exit status of all programs run using @var{obj}. | |
209 | @var{count} is the number of results expected. The results will be | |
210 | placed into @var{vector}. The results are in the order of the calls | |
211 | to @code{pex_run}. Returns 0 on error, 1 on success. | |
212 | ||
213 | @end deftypefn | |
214 | ||
215 | @deftypefn Extension int pex_get_times (struct pex_obj *@var{obj}, int @var{count}, struct pex_time *@var{vector}) | |
5a17353c | 216 | |
b109e79a ILT |
217 | Returns the process execution times of all programs run using |
218 | @var{obj}. @var{count} is the number of results expected. The | |
219 | results will be placed into @var{vector}. The results are in the | |
220 | order of the calls to @code{pex_run}. Returns 0 on error, 1 on | |
221 | success. | |
5a17353c | 222 | |
f13c9bea DD |
223 | @code{struct pex_time} has the following fields of the type |
224 | @code{unsigned long}: @code{user_seconds}, | |
b109e79a ILT |
225 | @code{user_microseconds}, @code{system_seconds}, |
226 | @code{system_microseconds}. On systems which do not support reporting | |
227 | process times, all the fields will be set to @code{0}. | |
5a17353c | 228 | |
b109e79a ILT |
229 | @end deftypefn |
230 | ||
231 | @deftypefn Extension void pex_free (struct pex_obj @var{obj}) | |
5a17353c | 232 | |
b109e79a | 233 | Clean up and free all data associated with @var{obj}. |
5a17353c DD |
234 | |
235 | @end deftypefn | |
236 | ||
f13c9bea | 237 | @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}) |
b109e79a | 238 | |
f13c9bea | 239 | An interface to permit the easy execution of a |
b109e79a ILT |
240 | single program. The return value and most of the parameters are as |
241 | for a call to @code{pex_run}. @var{flags} is restricted to a | |
242 | combination of @code{PEX_SEARCH}, @code{PEX_STDERR_TO_STDOUT}, and | |
243 | @code{PEX_BINARY_OUTPUT}. @var{outname} is interpreted as if | |
f13c9bea | 244 | @code{PEX_LAST} were set. On a successful return, @code{*@var{status}} will |
b109e79a ILT |
245 | be set to the exit status of the program. |
246 | ||
247 | @end deftypefn | |
248 | ||
249 | @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 flags) | |
5a17353c | 250 | |
b109e79a ILT |
251 | This is the old interface to execute one or more programs. It is |
252 | still supported for compatibility purposes, but is no longer | |
253 | documented. | |
5a17353c | 254 | |
b109e79a ILT |
255 | @end deftypefn |
256 | ||
257 | @deftypefn Extension int pwait (int @var{pid}, int *@var{status}, int @var{flags}) | |
258 | ||
259 | Another part of the old execution interface. | |
260 | ||
261 | @end deftypefn |