[apple/libc.git] / gen / getobjformat.3

.\" Copyright (c) 1998 John D. Polstra
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD: src/lib/libc/gen/getobjformat.3,v 1.8 2001/10/01 16:08:51 ru Exp $
.\"
.Dd September 7, 1998
.Dt GETOBJFORMAT 3
.Os
.Sh NAME
.Nm getobjformat
.Nd get preferred object file format
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In objformat.h
.Ft int
.Fn getobjformat "char *buf" "size_t bufsize" "int *argcp" "char **argv"
.Sh DESCRIPTION
.Fn getobjformat
queries several sources to determine the preferred object file
format, and copies its name into a buffer provided by the caller.
.Pp
The object file format is determined as follows.  If
.Va argv
is
.No non- Ns Ev NULL
and an explicit command line argument such as
.Fl aout
or
.Fl elf
is present, then that determines the object file format.
.Pp
Otherwise, if the variable
.Ev OBJFORMAT
is set in the environment, the object file format is taken from its
value.
.Pp
Otherwise, if the file
.Pa /etc/objformat
is readable and contains a line of the form
.Ql OBJFORMAT=xxx ,
the object file format is taken from there.
.Pp
Otherwise, a built-in system default object file format is returned.
.Pp
.Va buf
points to a user-supplied buffer into which the name of the object
file format is copied.
.Va bufsize
gives the size of the buffer in bytes.  The string placed in
.Va buf
is always null-terminated.  It is an error if the buffer is too
small to hold the null-terminated name.
.Pp
.Va argv
points to a
.Dv NULL Ns -terminated
argument vector to be scanned for object
format options.
.Va argv
may be
.Dv NULL ,
in which case the argument vector is not scanned.
.Pp
If
.Va argcp
is non-NULL, any object format options are deleted from the
argument vector, and the updated argument count is stored into
the integer referenced by
.Va argcp .
If
.Va argcp
is
.Dv NULL ,
the argument vector is left unchanged.
.Sh RETURN VALUES
On success,
.Fn getobjformat
returns the length of the object file format name, not counting the
null terminator.
If the supplied buffer is too small to hold the object file format
and its null terminator,
.Fn getobjformat
returns -1.  In that case, the contents of the buffer and argument
vector supplied by the caller are indeterminate.
.Sh ENVIRONMENT
.Bl -tag -width OBJFORMAT
.It Ev OBJFORMAT
If the environment variable
.Ev OBJFORMAT
is set, it overrides the default object file format.
.Ev OBJFORMAT takes precedence over
.Pa /etc/objformat .
.El
.Sh FILES
.Bl -tag -width /etc/objformat -compact
.It Pa /etc/objformat
If present, specifies the object file format to use.  Syntax is
.Ql OBJFORMAT=xxx .
.El
.Sh SEE ALSO
.Xr objformat 1
.Sh HISTORY
The
.Fn getobjformat
function first appeared in
.Fx 3.0 .
Commit	Line	Data
5b2abdfb A	1	.\" Copyright (c) 1998 John D. Polstra
	2	.\" All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	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
	15	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	16	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
	17	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	18	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	19	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	20	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	21	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	22	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	23	.\" SUCH DAMAGE.
	24	.\"
	25	.\" $FreeBSD: src/lib/libc/gen/getobjformat.3,v 1.8 2001/10/01 16:08:51 ru Exp $
	26	.\"
	27	.Dd September 7, 1998
	28	.Dt GETOBJFORMAT 3
	29	.Os
	30	.Sh NAME
	31	.Nm getobjformat
	32	.Nd get preferred object file format
	33	.Sh LIBRARY
	34	.Lb libc
	35	.Sh SYNOPSIS
	36	.In objformat.h
	37	.Ft int
	38	.Fn getobjformat "char buf" "size_t bufsize" "int argcp" "char **argv"
	39	.Sh DESCRIPTION
	40	.Fn getobjformat
	41	queries several sources to determine the preferred object file
	42	format, and copies its name into a buffer provided by the caller.
	43	.Pp
	44	The object file format is determined as follows. If
	45	.Va argv
	46	is
	47	.No non- Ns Ev NULL
	48	and an explicit command line argument such as
	49	.Fl aout
	50	or
	51	.Fl elf
	52	is present, then that determines the object file format.
	53	.Pp
	54	Otherwise, if the variable
	55	.Ev OBJFORMAT
	56	is set in the environment, the object file format is taken from its
	57	value.
	58	.Pp
	59	Otherwise, if the file
	60	.Pa /etc/objformat
	61	is readable and contains a line of the form
	62	.Ql OBJFORMAT=xxx ,
	63	the object file format is taken from there.
	64	.Pp
65	Otherwise, a built-in system default object file format is returned.
66	.Pp
67	.Va buf
68	points to a user-supplied buffer into which the name of the object
69	file format is copied.
70	.Va bufsize
71	gives the size of the buffer in bytes. The string placed in
72	.Va buf
73	is always null-terminated. It is an error if the buffer is too
74	small to hold the null-terminated name.
75	.Pp
76	.Va argv
77	points to a
78	.Dv NULL Ns -terminated
79	argument vector to be scanned for object
80	format options.
81	.Va argv
82	may be
83	.Dv NULL ,
84	in which case the argument vector is not scanned.
85	.Pp
86	If
87	.Va argcp
88	is non-NULL, any object format options are deleted from the
89	argument vector, and the updated argument count is stored into
90	the integer referenced by
91	.Va argcp .
92	If
93	.Va argcp
94	is
95	.Dv NULL ,
96	the argument vector is left unchanged.
97	.Sh RETURN VALUES
98	On success,
99	.Fn getobjformat
100	returns the length of the object file format name, not counting the
101	null terminator.
102	If the supplied buffer is too small to hold the object file format
103	and its null terminator,
104	.Fn getobjformat
105	returns -1. In that case, the contents of the buffer and argument
106	vector supplied by the caller are indeterminate.
107	.Sh ENVIRONMENT
108	.Bl -tag -width OBJFORMAT
109	.It Ev OBJFORMAT
110	If the environment variable
111	.Ev OBJFORMAT
112	is set, it overrides the default object file format.
113	.Ev OBJFORMAT takes precedence over
114	.Pa /etc/objformat .
115	.El
116	.Sh FILES
117	.Bl -tag -width /etc/objformat -compact
118	.It Pa /etc/objformat
119	If present, specifies the object file format to use. Syntax is
120	.Ql OBJFORMAT=xxx .
121	.El
122	.Sh SEE ALSO
123	.Xr objformat 1
124	.Sh HISTORY
125	The
126	.Fn getobjformat
127	function first appeared in
128	.Fx 3.0 .