1.\" Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
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25.\" Portions of this text are reprinted and reproduced in electronic form
26.\" from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology --
27.\" Portable Operating System Interface (POSIX), The Open Group Base
28.\" Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of
29.\" Electrical and Electronics Engineers, Inc and The Open Group.  In the
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32.\" the referee document.  The original Standard can be obtained online at
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35.\" $FreeBSD$
36.\"
37.Dd May 9, 2013
38.Dt POSIX_SPAWN_FILE_ACTIONS_ADDOPEN 3
39.Os
40.Sh NAME
41.Nm posix_spawn_file_actions_addopen ,
42.Nm posix_spawn_file_actions_adddup2 ,
43.Nm posix_spawn_file_actions_addclose ,
44.Nm posix_spawn_file_actions_addclosefrom_np ,
45.Nm posix_spawn_file_actions_addchdir_np ,
46.Nm posix_spawn_file_actions_addfchdir_np
47.Nd "add open, dup2, close, closefrom, or chdir/fchdir actions to spawn file actions object"
48.Sh LIBRARY
49.Lb libc
50.Sh SYNOPSIS
51.In spawn.h
52.Ft int
53.Fo posix_spawn_file_actions_addopen
54.Fa "posix_spawn_file_actions_t * file_actions"
55.Fa "int fildes"
56.Fa "const char *restrict path"
57.Fa "int oflag"
58.Fa "mode_t mode"
59.Fc
60.Ft int
61.Fo posix_spawn_file_actions_adddup2
62.Fa "posix_spawn_file_actions_t * file_actions"
63.Fa "int fildes"
64.Fa "int newfildes"
65.Fc
66.Ft int
67.Fo posix_spawn_file_actions_addclose
68.Fa "posix_spawn_file_actions_t * file_actions"
69.Fa "int fildes"
70.Fc
71.Ft int
72.Fo posix_spawn_file_actions_addclosefrom_np
73.Fa "posix_spawn_file_actions_t * file_actions"
74.Fa "int from"
75.Fc
76.Ft int
77.Fo posix_spawn_file_actions_addchdir_np
78.Fa "posix_spawn_file_actions_t *restrict file_actions"
79.Fa "const char *restrict path"
80.Fc
81.Ft int
82.Fo posix_spawn_file_actions_addfchdir_np
83.Fa "posix_spawn_file_actions_t * file_actions"
84.Fa "int fildes"
85.Fc
86.Sh DESCRIPTION
87These functions add an open, dup2 or close action to a spawn
88file actions object.
89.Pp
90A spawn file actions object is of type
91.Vt posix_spawn_file_actions_t
92(defined in
93.In spawn.h )
94and is used to specify a series of actions to be performed by a
95.Fn posix_spawn
96or
97.Fn posix_spawnp
98operation in order to arrive at the set of open file descriptors for the
99child process given the set of open file descriptors of the parent.
100.Pp
101A spawn file actions object, when passed to
102.Fn posix_spawn
103or
104.Fn posix_spawnp ,
105specify how the set of open file descriptors in the calling
106process is transformed into a set of potentially open file descriptors
107for the spawned process.
108This transformation is as if the specified sequence of actions was
109performed exactly once, in the context of the spawned process (prior to
110execution of the new process image), in the order in which the actions
111were added to the object; additionally, when the new process image is
112executed, any file descriptor (from this new set) which has its
113.Dv FD_CLOEXEC
114flag set is closed (see
115.Fn posix_spawn ) .
116.Pp
117The
118.Fn posix_spawn_file_actions_addopen
119function adds an open action to the object referenced by
120.Fa file_actions
121that causes the file named by
122.Fa path
123to be opened (as if
124.Bd -literal -offset indent
125open(path, oflag, mode)
126.Ed
127.Pp
128had been called, and the returned file descriptor, if not
129.Fa fildes ,
130had been changed to
131.Fa fildes )
132when a new process is spawned using this file actions object.
133If
134.Fa fildes
135was already an open file descriptor, it is closed before the new
136file is opened.
137.Pp
138The string described by
139.Fa path
140is copied by the
141.Fn posix_spawn_file_actions_addopen
142function.
143.Pp
144The
145.Fn posix_spawn_file_actions_adddup2
146function adds a dup2 action to the object referenced by
147.Fa file_actions
148that causes the file descriptor
149.Fa fildes
150to be duplicated as
151.Fa newfildes
152(as if
153.Bd -literal -offset indent
154dup2(fildes, newfildes)
155.Ed
156.Pp
157had been called) when a new process is spawned using this file actions object,
158except that the
159.Dv FD_CLOEXEC
160flag for
161.Fa newfildes
162is cleared even if
163.Fa fildes
164is equal to
165.Fa newfildes .
166The difference from
167.Fn dup2
168is useful for passing a particular file descriptor
169to a particular child process.
170.Pp
171The
172.Fn posix_spawn_file_actions_addclose
173function adds a close action to the object referenced by
174.Fa file_actions
175that causes the file descriptor
176.Fa fildes
177to be closed (as if
178.Bd -literal -offset indent
179close(fildes)
180.Ed
181.Pp
182had been called) when a new process is spawned using this file actions
183object.
184.Pp
185The
186.Fn posix_spawn_file_actions_addclosefrom_np
187function adds a close action to close all file descriptors numerically
188equal or greater then the argument
189.Fa from .
190For each open file descriptor, logically the close action is performed,
191and any possible errors encountered are ignored.
192.Pp
193The
194.Fn posix_spawn_file_actions_addchdir_np
195and
196.Fn posix_spawn_file_actions_addfchdir_np
197functions add a change current directory action to the object
198referenced by
199.Fa file_actions
200that affects actions (opens with relative path) performed after the operation,
201in the order of insertion into the
202.Fa file_actions
203object.
204It also sets the working directory for the spawned program.
205The
206.Fn posix_spawn_file_actions_addchdir_np
207function takes the
208.Fa path
209to set as the working directory, while
210.Fn posix_spawn_file_actions_addfchdir_np
211takes the directory file descriptor.
212.Sh RETURN VALUES
213Upon successful completion, these functions return zero;
214otherwise, an error number is returned to indicate the error.
215.Sh ERRORS
216These
217functions fail if:
218.Bl -tag -width Er
219.It Bq Er EBADF
220The value specified by
221.Fa fildes
222or
223.Fa newfildes
224is negative.
225.It Bq Er ENOMEM
226Insufficient memory exists to add to the spawn file actions object.
227.El
228.Sh SEE ALSO
229.Xr close 2 ,
230.Xr dup2 2 ,
231.Xr open 2 ,
232.Xr posix_spawn 3 ,
233.Xr posix_spawn_file_actions_destroy 3 ,
234.Xr posix_spawn_file_actions_init 3 ,
235.Xr posix_spawnp 3
236.Sh STANDARDS
237The
238.Fn posix_spawn_file_actions_addopen ,
239.Fn posix_spawn_file_actions_adddup2
240and
241.Fn posix_spawn_file_actions_addclose
242functions conform to
243.St -p1003.1-2001 ,
244with the exception of the behavior of
245.Fn posix_spawn_file_actions_adddup2
246if
247.Fa fildes
248is equal to
249.Fa newfildes
250(clearing
251.Dv FD_CLOEXEC ) .
252A future update of the Standard is expected to require this behavior.
253.Pp
254The
255.Fn posix_spawn_file_actions_addchdir_np ,
256.Fn posix_spawn_file_actions_addfchdir_np ,
257and
258.Fn posix_spawn_file_actions_addclosefrom_np
259functions are non-standard functions implemented after the similar
260functionality provided by glibc.
261.Sh HISTORY
262The
263.Fn posix_spawn_file_actions_addopen ,
264.Fn posix_spawn_file_actions_adddup2
265and
266.Fn posix_spawn_file_actions_addclose
267functions first appeared in
268.Fx 8.0 .
269The
270.Fn posix_spawn_file_actions_addchdir_np ,
271.Fn posix_spawn_file_actions_addfchdir_np ,
272and
273.Fn posix_spawn_file_actions_addclosefrom_np
274functions first appeared in
275.Fx 14.0 .
276.Sh AUTHORS
277.An \&Ed Schouten Aq Mt ed@FreeBSD.org
278