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explain_setenv(3)	   Library Functions Manual	     explain_setenv(3)

NAME
       explain_setenv -	explain	setenv(3) errors

SYNOPSIS
       #include	<libexplain/setenv.h>
       const char *explain_setenv(const	char *name, const char *value, int
       overwrite);
       const char *explain_errno_setenv(int errnum, const char *name, const
       char *value, int	overwrite);
       void explain_message_setenv(char	*message, int message_size, const char
       *name, const char *value, int overwrite);
       void explain_message_errno_setenv(char *message,	int message_size, int
       errnum, const char *name, const char *value, int	overwrite);

DESCRIPTION
       These  functions	may be used to obtain explanations for errors returned
       by the setenv(3)	system call.

   explain_setenv
       const char *explain_setenv(const	char *name, const char *value, int
       overwrite);

       The  explain_setenv function is used to obtain an explanation of	an er-
       ror returned by the setenv(3) system call. The least the	 message  will
       contain	is  the	 value of strerror(errno), but usually it will do much
       better, and indicate the	underlying cause in more detail.

       The errno global	variable will be used to obtain	the error value	to  be
       decoded.

       name    The  original  name,  exactly as	passed to the setenv(3)	system
	       call.

       value   The original value, exactly as passed to	the  setenv(3)	system
	       call.

       overwrite
	       The original overwrite, exactly as passed to the	setenv(3) sys-
	       tem call.

       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.

       Note: This function is not thread safe, because it shares a return buf-
       fer across all threads, and many	other functions	in this	library.

       Example:	 This  function	is intended to be used in a fashion similar to
       the following example:
	      if (setenv(name, value, overwrite) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_setenv(name, value, over-
		  write));
		  exit(EXIT_FAILURE);
	      }

       The   above   code   example  is	 available  pre-packaged  as  the  ex-
       plain_setenv_or_die(3) function.

   explain_errno_setenv
       const char *explain_errno_setenv(int errnum, const char *name, const
       char *value, int	overwrite);

       The  explain_errno_setenv  function is used to obtain an	explanation of
       an error	returned by the	setenv(3) system call. The least  the  message
       will  contain  is  the value of strerror(errno),	but usually it will do
       much better, and	indicate the underlying	cause in more detail.

       errnum  The error value to be decoded, usually obtained from the	 errno
	       global  variable	 just  before this function is called. This is
	       necessary if you	need to	call any code between the system  call
	       to  be explained	and this function, because many	libc functions
	       will alter the value of errno.

       name    The original name, exactly as passed to	the  setenv(3)	system
	       call.

       value   The  original  value, exactly as	passed to the setenv(3)	system
	       call.

       overwrite
	       The original overwrite, exactly as passed to the	setenv(3) sys-
	       tem call.

       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.

       Note: This function is not thread safe, because it shares a return buf-
       fer across all threads, and many	other functions	in this	library.

       Example:	This function is intended to be	used in	a fashion  similar  to
       the following example:
	      if (setenv(name, value, overwrite) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_setenv(err, name,
		  value, overwrite));
		  exit(EXIT_FAILURE);
	      }

       The  above  code	 example  is  available	 pre-packaged	as   the   ex-
       plain_setenv_or_die(3) function.

   explain_message_setenv
       void explain_message_setenv(char	*message, int message_size, const char
       *name, const char *value, int overwrite);

       The explain_message_setenv function is used to obtain an	explanation of
       an  error  returned by the setenv(3) system call. The least the message
       will contain is the value of strerror(errno), but usually  it  will  do
       much better, and	indicate the underlying	cause in more detail.

       The  errno global variable will be used to obtain the error value to be
       decoded.

       message The location in which to	store the returned message. If a suit-
	       able message return buffer is supplied, this function is	thread
	       safe.

       message_size
	       The size	in bytes of the	location in which  to  store  the  re-
	       turned message.

       name    The  original  name,  exactly as	passed to the setenv(3)	system
	       call.

       value   The original value, exactly as passed to	the  setenv(3)	system
	       call.

       overwrite
	       The original overwrite, exactly as passed to the	setenv(3) sys-
	       tem call.

       Example:	This function is intended to be	used in	a fashion  similar  to
       the following example:
	      if (setenv(name, value, overwrite) < 0)
	      {
		  char message[3000];
		  explain_message_setenv(message, sizeof(message), name,
		  value, overwrite);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       The  above  code	 example  is  available	 pre-packaged	as   the   ex-
       plain_setenv_or_die(3) function.

   explain_message_errno_setenv
       void explain_message_errno_setenv(char *message,	int message_size, int
       errnum, const char *name, const char *value, int	overwrite);

       The explain_message_errno_setenv	function is used to obtain an explana-
       tion  of	 an error returned by the setenv(3) system call. The least the
       message will contain is the value of strerror(errno),  but  usually  it
       will do much better, and	indicate the underlying	cause in more detail.

       message The location in which to	store the returned message. If a suit-
	       able message return buffer is supplied, this function is	thread
	       safe.

       message_size
	       The  size  in  bytes  of	the location in	which to store the re-
	       turned message.

       errnum  The error value to be decoded, usually obtained from the	 errno
	       global  variable	 just  before this function is called. This is
	       necessary if you	need to	call any code between the system  call
	       to  be explained	and this function, because many	libc functions
	       will alter the value of errno.

       name    The original name, exactly as passed to	the  setenv(3)	system
	       call.

       value   The  original  value, exactly as	passed to the setenv(3)	system
	       call.

       overwrite
	       The original overwrite, exactly as passed to the	setenv(3) sys-
	       tem call.

       Example:	 This  function	is intended to be used in a fashion similar to
       the following example:
	      if (setenv(name, value, overwrite) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_setenv(message,	sizeof(message), err,
		  name,	value, overwrite);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       The   above   code   example  is	 available  pre-packaged  as  the  ex-
       plain_setenv_or_die(3) function.

SEE ALSO
       setenv(3)
	       change or add an	environment variable

       explain_setenv_or_die(3)
	       change or add an	environment variable and report	errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2010 Peter	Miller

							     explain_setenv(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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