.lf 1 ./man/man3/explain_setenv.3
.\"
.\" libexplain - Explain errno values returned by libc functions
.\" Copyright (C) 2010, 2011 Peter Miller
.\"
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.\" under the terms of the GNU General Public License as published by the
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.\" option) any later version.
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.\" ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
.\" GNULesser General Public License for more details.
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.\"
.ds n) explain_setenv
.cp 0  \" Solaris defaults to ''.cp 1'', sheesh.
.TH explain_setenv 3
.SH NAME
explain_setenv \- explain \f[I]setenv\fP(3) errors
.if require_index \{
.\}
.SH SYNOPSIS
#include <libexplain/setenv.h>
.sp 0.3
.ad l
const char *explain_setenv(const char *name, const char *value, int
overwrite);
.br
const char *explain_errno_setenv(int errnum, const char *name, const char
*value, int overwrite);
.br
void explain_message_setenv(char *message, int message_size, const char
*name, const char *value, int overwrite);
.br
void explain_message_errno_setenv(char *message, int message_size, int
errnum, const char *name, const char *value, int overwrite);
.ad b
.SH DESCRIPTION
These functions may be used to obtain explanations for errors returned by
the \f[I]setenv\fP(3) system call.
.\" ----------------------------------------------------
.SS explain_setenv
.ad l
const char *explain_setenv(const char *name, const char *value, int
overwrite);
.ad b
.PP
The \f[B]explain_setenv\fP function is used to obtain an explanation of an
error returned by the \f[I]setenv\fP(3) system call. The least the message
will contain is the value of \f[CW]strerror(errno)\fP, but usually it will
do much better, and indicate the underlying cause in more detail.
.PP
The \f[I]errno\fP global variable will be used to obtain the error value to
be decoded.
.TP 8n
\f[I]name\fP
The original name, exactly as passed to the \f[I]setenv\fP(3) system call.
.TP 8n
\f[I]value\fP
The original value, exactly as passed to the \f[I]setenv\fP(3) system call.
.TP 8n
\f[I]overwrite\fP
The original overwrite, exactly as passed to the \f[I]setenv\fP(3) system
call.
.TP 8n
Returns:
The message explaining the error. This message buffer is shared by all
libexplain functions which do not supply a buffer in their argument list.
This will be overwritten by the next call to any libexplain function which
shares this buffer, including other threads.
.PP
\f[B]Note:\fP This function is \f[B]not\fP thread safe, because it shares a
return buffer across all threads, and many other functions in this library.
.PP
\f[B]Example:\fP This function is intended to be used in a fashion similar
to the following example:
.RS
.ft CW
.fi
.ad l
if (setenv(name, value, overwrite) < 0)
.ad b
.nf
{
.fi
.ad l
.in +4n
fprintf(stderr, "%s\en", explain_setenv(name, value, overwrite));
.in -4n
.nf
    exit(EXIT_FAILURE);
}
.fi
.ft R
.ad b
.RE
.PP
The above code example is available pre\[hy]packaged as the
\f[I]explain_setenv_or_die\fP(3) function.
.\" ----------------------------------------------------
.SS explain_errno_setenv
.ad l
const char *explain_errno_setenv(int errnum, const char *name, const char
*value, int overwrite);
.ad b
.PP
The \f[B]explain_errno_setenv\fP function is used to obtain an explanation
of an error returned by the \f[I]setenv\fP(3) system call. The least the
message will contain is the value of \f[CW]strerror(errno)\fP, but usually
it will do much better, and indicate the underlying cause in more detail.
.TP 8n
\f[I]errnum\fP
The error value to be decoded, usually obtained from the \f[I]errno\fP
global variable just before this function is called. This is necessary if
you need to call \f[B]any\fP code between the system call to be explained
and this function, because many libc functions will alter the value of
\f[I]errno\fP.
.TP 8n
\f[I]name\fP
The original name, exactly as passed to the \f[I]setenv\fP(3) system call.
.TP 8n
\f[I]value\fP
The original value, exactly as passed to the \f[I]setenv\fP(3) system call.
.TP 8n
\f[I]overwrite\fP
The original overwrite, exactly as passed to the \f[I]setenv\fP(3) system
call.
.TP 8n
Returns:
The message explaining the error. This message buffer is shared by all
libexplain functions which do not supply a buffer in their argument list.
This will be overwritten by the next call to any libexplain function which
shares this buffer, including other threads.
.PP
\f[B]Note:\fP This function is \f[B]not\fP thread safe, because it shares a
return buffer across all threads, and many other functions in this library.
.PP
\f[B]Example:\fP This function is intended to be used in a fashion similar
to the following example:
.RS
.ft CW
.fi
.ad l
if (setenv(name, value, overwrite) < 0)
.ad b
.nf
{
    int err = errno;
.fi
.ad l
.in +4n
fprintf(stderr, "%s\en", explain_errno_setenv(err, name, value,
overwrite));
.in -4n
.nf
    exit(EXIT_FAILURE);
}
.fi
.ft R
.ad b
.RE
.PP
The above code example is available pre\[hy]packaged as the
\f[I]explain_setenv_or_die\fP(3) function.
.\" ----------------------------------------------------
.SS explain_message_setenv
.ad l
void explain_message_setenv(char *message, int message_size, const char
*name, const char *value, int overwrite);
.ad b
.PP
The \f[B]explain_message_setenv\fP function is used to obtain an
explanation of an error returned by the \f[I]setenv\fP(3) system call. The
least the message will contain is the value of \f[CW]strerror(errno)\fP,
but usually it will do much better, and indicate the underlying cause in
more detail.
.PP
The \f[I]errno\fP global variable will be used to obtain the error value to
be decoded.
.TP 8n
\f[I]message\fP
The location in which to store the returned message. If a suitable message
return buffer is supplied, this function is thread safe.
.TP 8n
\f[I]message_size\fP
The size in bytes of the location in which to store the returned message.
.TP 8n
\f[I]name\fP
The original name, exactly as passed to the \f[I]setenv\fP(3) system call.
.TP 8n
\f[I]value\fP
The original value, exactly as passed to the \f[I]setenv\fP(3) system call.
.TP 8n
\f[I]overwrite\fP
The original overwrite, exactly as passed to the \f[I]setenv\fP(3) system
call.
.PP
\f[B]Example:\fP This function is intended to be used in a fashion similar
to the following example:
.RS
.ft CW
.fi
.ad l
if (setenv(name, value, overwrite) < 0)
.ad b
.nf
{
    char message[3000];
.in +4n
.fi
.ad l
explain_message_setenv(message, sizeof(message), name, value, overwrite);
.nf
.in -4n
    fprintf(stderr, "%s\en", message);
    exit(EXIT_FAILURE);
}
.fi
.ft R
.ad b
.RE
.PP
The above code example is available pre\[hy]packaged as the
\f[I]explain_setenv_or_die\fP(3) function.
.\" ----------------------------------------------------
.SS explain_message_errno_setenv
.ad l
void explain_message_errno_setenv(char *message, int message_size, int
errnum, const char *name, const char *value, int overwrite);
.ad b
.PP
The \f[B]explain_message_errno_setenv\fP function is used to obtain an
explanation of an error returned by the \f[I]setenv\fP(3) system call. The
least the message will contain is the value of \f[CW]strerror(errno)\fP,
but usually it will do much better, and indicate the underlying cause in
more detail.
.TP 8n
\f[I]message\fP
The location in which to store the returned message. If a suitable message
return buffer is supplied, this function is thread safe.
.TP 8n
\f[I]message_size\fP
The size in bytes of the location in which to store the returned message.
.TP 8n
\f[I]errnum\fP
The error value to be decoded, usually obtained from the \f[I]errno\fP
global variable just before this function is called. This is necessary if
you need to call \f[B]any\fP code between the system call to be explained
and this function, because many libc functions will alter the value of
\f[I]errno\fP.
.TP 8n
\f[I]name\fP
The original name, exactly as passed to the \f[I]setenv\fP(3) system call.
.TP 8n
\f[I]value\fP
The original value, exactly as passed to the \f[I]setenv\fP(3) system call.
.TP 8n
\f[I]overwrite\fP
The original overwrite, exactly as passed to the \f[I]setenv\fP(3) system
call.
.PP
\f[B]Example:\fP This function is intended to be used in a fashion similar
to the following example:
.RS
.ft CW
.fi
.ad l
if (setenv(name, value, overwrite) < 0)
.ad b
.nf
{
    int err = errno;
    char message[3000];
.in +4n
.fi
.ad l
explain_message_errno_setenv(message, sizeof(message), err, name, value,
overwrite);
.nf
.in -4n
    fprintf(stderr, "%s\en", message);
    exit(EXIT_FAILURE);
}
.fi
.ft R
.ad b
.RE
.PP
The above code example is available pre\[hy]packaged as the
\f[I]explain_setenv_or_die\fP(3) function.
.\" ----------------------------------------------------
.SH SEE ALSO
.TP 8n
\f[I]setenv\fP(3)
change or add an environment variable
.TP 8n
\f[I]explain_setenv_or_die\fP(3)
change or add an environment variable and report errors
.\" ----------------------------------------------------
.SH COPYRIGHT
.lf 1 ./etc/version.so
.ds v) 1.4
.ds V) 1.4.D001
.ds Y) 2008, 2009, 2010, 2011, 2012, 2013, 2014
.lf 306 ./man/man3/explain_setenv.3
.if n .ds C) (C)
.if t .ds C) \(co
libexplain version \*(v)
.br
Copyright \*(C) 2010 Peter Miller
.\" vim: set ts=8 sw=4 et