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explain_execve(3)	   Library Functions Manual	     explain_execve(3)

NAME
       explain_execve -	explain	execve(2) errors

SYNOPSIS
       #include	<libexplain/execve.h>
       const  char  *explain_execve(const  char	 *pathname,  const char	*const
       *argv, const char *const	*envp);
       const char  *explain_errno_execve(int  errnum,  const  char  *pathname,
       const char *const *argv,	const char *const *envp);
       void explain_message_execve(char	*message, int message_size, const char
       *pathname, const	char *const *argv, const char *const *envp);
       void explain_message_errno_execve(char *message,	int message_size,  int
       errnum,	const  char  *pathname,	 const	char  *const *argv, const char
       *const *envp);

DESCRIPTION
       These functions may be used to obtain explanations for errors  returned
       by the execve(2)	system call.

   explain_execve
       const  char  *explain_execve(const  char	 *pathname,  const char	*const
       *argv, const char *const	*envp);

       The explain_execve function is used to obtain an	explanation of an  er-
       ror  returned by	the execve(2) 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.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      execve(pathname, argv, envp);
	      fprintf(stderr, "%s\n", explain_execve(pathname, argv, envp));
	      exit(EXIT_FAILURE);

       pathname
	       The  original pathname, exactly as passed to the	execve(2) sys-
	       tem call.

       argv    The original argv, exactly as passed to	the  execve(2)	system
	       call.

       envp    The  original  envp,  exactly as	passed to the execve(2)	system
	       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, in-
	       cluding 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.

   explain_errno_execve
       const  char  *explain_errno_execve(int  errnum,	const  char *pathname,
       const char *const *argv,	const char *const *envp);

       The explain_errno_execve	function is used to obtain an  explanation  of
       an  error returned by the execve(2) system call.	 The least the message
       will contain is the value of strerror(errnum), but usually it  will  do
       much better, and	indicate the underlying	cause in more detail.

       This  function  is intended to be used in a fashion similar to the fol-
       lowing example:
	      execve(pathname, argv, envp);
	      int err =	errno;
	      fprintf(stderr, "%s\n", explain_errno_execve(err,	pathname, argv,	envp));
	      exit(EXIT_FAILURE);

       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.

       pathname
	       The original pathname, exactly as passed	to the execve(2)  sys-
	       tem call.

       argv    The  original  argv,  exactly as	passed to the execve(2)	system
	       call.

       envp    The original envp, exactly as passed to	the  execve(2)	system
	       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,  in-
	       cluding 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.

   explain_message_execve
       void explain_message_execve(char	*message, int message_size, const char
       *pathname, const	char *const *argv, const char *const *envp);

       The  explain_message_execve function may	be used	to  obtain an explana-
       tion of an error	returned by the	execve(2) 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.

       This  function  is intended to be used in a fashion similar to the fol-
       lowing example:
	      execve(pathname, argv, envp);
	      char message[3000];
	      explain_message_execve(message, sizeof(message), pathname, argv, envp);
	      fprintf(stderr, "%s\n", message);
	      exit(EXIT_FAILURE);

       message The location in which to	store  the  returned  message.	 If  a
	       suitable	 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.

       pathname
	       The  original pathname, exactly as passed to the	execve(2) sys-
	       tem call.

       argv    The original argv, exactly as passed to	the  execve(2)	system
	       call.

       envp    The  original  envp,  exactly as	passed to the execve(2)	system
	       call.

   explain_message_errno_execve
       void explain_message_errno_execve(char *message,	int message_size,  int
       errnum,	const  char  *pathname,	 const	char  *const *argv, const char
       *const *envp);

       The explain_message_errno_execve	function may be	used to	obtain an  ex-
       planation of an error returned by the execve(2) system call.  The least
       the message will	contain	is the value of	strerror(errnum), but  usually
       it  will	 do much better, and indicate the underlying cause in more de-
       tail.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      execve(pathname, argv, envp);
	      int err =	errno;
	      char message[3000];
	      explain_message_errno_execve(message, sizeof(message), err,
		  pathname, argv, envp);
	      fprintf(stderr, "%s\n", message);
	      exit(EXIT_FAILURE);

       message The  location  in  which	 to  store the returned	message.  If a
	       suitable	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.

       pathname
	       The original pathname, exactly as passed	to the execve(2)  sys-
	       tem call.

       argv    The  original  argv,  exactly as	passed to the execve(2)	system
	       call.

       envp    The original envp, exactly as passed to	the  execve(2)	system
	       call.

SEE ALSO
       execve(2)
	       execute program

       explain_execve_or_die(3)
	       execute program and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2008 Peter	Miller

							     explain_execve(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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