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[dragonfly.git] / lib / libc / gen / getobjformat.3
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1.\" Copyright (c) 1998 John D. Polstra
2.\" All rights reserved.
3.\"
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5.\" modification, are permitted provided that the following conditions
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7.\" 1. Redistributions of source code must retain the above copyright
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9.\" 2. Redistributions in binary form must reproduce the above copyright
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11.\" documentation and/or other materials provided with the distribution.
12.\"
13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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25.\" $FreeBSD: src/lib/libc/gen/getobjformat.3,v 1.3.2.6 2003/03/13 18:05:37 trhodes Exp $
1de703da 26.\" $DragonFly: src/lib/libc/gen/getobjformat.3,v 1.2 2003/06/17 04:26:42 dillon Exp $
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27.\"
28.Dd September 7, 1998
29.Dt GETOBJFORMAT 3
30.Os
31.Sh NAME
32.Nm getobjformat
33.Nd get preferred object file format
34.Sh LIBRARY
35.Lb libc
36.Sh SYNOPSIS
37.In objformat.h
38.Ft int
39.Fn getobjformat "char *buf" "size_t bufsize" "int *argcp" "char **argv"
40.Sh DESCRIPTION
41The
42.Fn getobjformat
43function
44queries several sources to determine the preferred object file
45format, and copies its name into a buffer provided by the caller.
46.Pp
47The object file format is determined as follows. If
48.Va argv
49is
50.No non- Ns Ev NULL
51and an explicit command line argument such as
52.Fl aout
53or
54.Fl elf
55is present, then that determines the object file format.
56.Pp
57Otherwise, if the variable
58.Ev OBJFORMAT
59is set in the environment, the object file format is taken from its
60value.
61.Pp
62Otherwise, if the file
63.Pa /etc/objformat
64is readable and contains a line of the form
65.Ql OBJFORMAT=xxx ,
66the object file format is taken from there.
67.Pp
68Otherwise, a built-in system default object file format is returned.
69.Pp
70.Va buf
71points to a user-supplied buffer into which the name of the object
72file format is copied.
73.Va bufsize
74gives the size of the buffer in bytes. The string placed in
75.Va buf
76is always null-terminated. It is an error if the buffer is too
77small to hold the null-terminated name.
78.Pp
79.Va argv
80points to a
81.Dv NULL Ns -terminated
82argument vector to be scanned for object
83format options.
84.Va argv
85may be
86.Dv NULL ,
87in which case the argument vector is not scanned.
88.Pp
89If
90.Va argcp
91is non-NULL, any object format options are deleted from the
92argument vector, and the updated argument count is stored into
93the integer referenced by
94.Va argcp .
95If
96.Va argcp
97is
98.Dv NULL ,
99the argument vector is left unchanged.
100.Sh RETURN VALUES
101On success,
102.Fn getobjformat
103returns the length of the object file format name, not counting the
104null terminator.
105If the supplied buffer is too small to hold the object file format
106and its null terminator,
107.Fn getobjformat
108returns -1. In that case, the contents of the buffer and argument
109vector supplied by the caller are indeterminate.
110.Sh ENVIRONMENT
111.Bl -tag -width OBJFORMAT
112.It Ev OBJFORMAT
113If the environment variable
114.Ev OBJFORMAT
115is set, it overrides the default object file format.
116.Ev OBJFORMAT takes precedence over
117.Pa /etc/objformat .
118.El
119.Sh FILES
120.Bl -tag -width /etc/objformat -compact
121.It Pa /etc/objformat
122If present, specifies the object file format to use. Syntax is
123.Ql OBJFORMAT=xxx .
124.El
125.Sh SEE ALSO
126.Xr objformat 1
127.Sh HISTORY
128The
129.Fn getobjformat
130function first appeared in
131.Fx 3.0 .