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explain_setregid(3)	    Library Functions Manual	     explain_setregid(3)

NAME
     explain_setregid - explain setregid(2) errors

SYNOPSIS
     #include <libexplain/setregid.h>
     const char *explain_setregid(gid_t rgid, gid_t egid);
     const char *explain_errno_setregid(int errnum, gid_t rgid, gid_t egid);
     void explain_message_setregid(char *message, int message_size, gid_t rgid,
     gid_t egid);
     void explain_message_errno_setregid(char *message, int message_size, int
     errnum, gid_t rgid, gid_t egid);

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

   explain_setregid
     const char *explain_setregid(gid_t rgid, gid_t egid);

     The explain_setregid function is used to obtain an explanation of an  error
     returned by the setregid(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  de-
     coded.

     rgid    The  original  rgid,  exactly  as	passed to the setregid(2) system
	     call.

     egid    The original egid, exactly as  passed  to	the  setregid(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  ar-
	     gument list.  This will be overwritten by the next call to any lib-
	     explain function which shares this buffer, including other threads.

     Note:  This  function is not thread safe, because it shares a return buffer
     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 (setregid(rgid, egid) < 0)
	    {
		fprintf(stderr, "%s\n", explain_setregid(rgid, egid));
		exit(EXIT_FAILURE);
	    }

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

   explain_errno_setregid
     const char *explain_errno_setregid(int errnum, gid_t rgid, gid_t egid);

     The explain_errno_setregid function is used to obtain an explanation of  an
     error  returned by the setregid(2) system call.  The least the message will
     contain is the value of strerror(errno), but usually it will do  much  bet-
     ter, 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 neces-
	     sary if you need to call any code between the system call to be ex-
	     plained and this function, because many libc functions  will  alter
	     the value of errno.

     rgid    The  original  rgid,  exactly  as	passed to the setregid(2) system
	     call.

     egid    The original egid, exactly as  passed  to	the  setregid(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  ar-
	     gument list.  This will be overwritten by the next call to any lib-
	     explain function which shares this buffer, including other threads.

     Note:  This  function is not thread safe, because it shares a return buffer
     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 (setregid(rgid, egid) < 0)
	    {
		int err = errno;
		fprintf(stderr, "%s\n", explain_errno_setregid(err, rgid,
		egid));
		exit(EXIT_FAILURE);
	    }

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

   explain_message_setregid
     void explain_message_setregid(char *message, int message_size, gid_t rgid,
     gid_t egid);

     The explain_message_setregid function is used to obtain an  explanation  of
     an  error	returned  by the setregid(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 de-
     coded.

     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 returned
	     message.

     rgid    The original rgid, exactly as  passed  to	the  setregid(2)  system
	     call.

     egid    The  original  egid,  exactly  as	passed to the setregid(2) system
	     call.

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

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

   explain_message_errno_setregid
     void explain_message_errno_setregid(char *message, int message_size, int
     errnum, gid_t rgid, gid_t egid);

     The explain_message_errno_setregid function is used to obtain  an	explana-
     tion  of  an  error returned by the setregid(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 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	returned
	     message.

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

     rgid    The  original  rgid,  exactly  as	passed to the setregid(2) system
	     call.

     egid    The original egid, exactly as  passed  to	the  setregid(2)  system
	     call.

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

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

SEE ALSO
     setregid(2)
	     set real and/or effective group ID

     explain_setregid_or_die(3)
	     set real and/or effective group ID and report errors

COPYRIGHT
     libexplain version 1.3
     Copyright (C) 2012 Peter Miller

							     explain_setregid(3)

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