Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
explain_chroot(3)	   Library Functions Manual	     explain_chroot(3)

NAME
       explain_chroot -	explain	chroot(2) errors

SYNOPSIS
       #include	<libexplain/chroot.h>
       const char *explain_chroot(const	char *pathname);
       const char *explain_errno_chroot(int errnum, const char *pathname);
       void explain_message_chroot(char	*message, int message_size, const char
       *pathname);
       void explain_message_errno_chroot(char *message,	int message_size, int
       errnum, const char *pathname);

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

   explain_chroot
       const char *explain_chroot(const	char *pathname);

       The explain_chroot function is used to obtain an	explanation of an  er-
       ror  returned  by the chroot(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.

       pathname
	       The original pathname, exactly as passed	to the chroot(2)  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 (chroot(pathname) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_chroot(pathname));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_chroot
       const char *explain_errno_chroot(int errnum, const char *pathname);

       The explain_errno_chroot	function is used to obtain an  explanation  of
       an  error  returned by the chroot(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.

       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	chroot(2) 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 (chroot(pathname) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_chroot(err, path-
		  name));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_chroot
       void explain_message_chroot(char	*message, int message_size, const char
       *pathname);

       The explain_message_chroot function is used to obtain an	explanation of
       an error	returned by the	chroot(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.

       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.

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

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

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

   explain_message_errno_chroot
       void explain_message_errno_chroot(char *message,	int message_size, int
       errnum, const char *pathname);

       The explain_message_errno_chroot	function is used to obtain an explana-
       tion  of	 an error returned by the chroot(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.

       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.

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

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

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

SEE ALSO
       chroot(2)
	       change root directory

       explain_chroot_or_die(3)
	       change root directory and report	errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2009 Peter	Miller

							     explain_chroot(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=explain_chroot&sektion=3&manpath=FreeBSD+12.2-RELEASE+and+Ports>

home | help