explain_shmat(3)					     Library Functions Manual						  explain_shmat(3)

NAME

       explain_shmat - explain shmat(2) errors

SYNOPSIS

       #include <libexplain/shmat.h>
       const char *explain_shmat(int shmid, const void *shmaddr, int shmflg);
       const char *explain_errno_shmat(int errnum, int shmid, const void *shmaddr, int shmflg);
       void explain_message_shmat(char *message, int message_size, int shmid, const void *shmaddr, int shmflg);
       void explain_message_errno_shmat(char *message, int message_size, int errnum, int shmid, const void *shmaddr, int shmflg);

DESCRIPTION

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

   explain_shmat
       const char *explain_shmat(int shmid, const void *shmaddr, int shmflg);

       The  explain_shmat  function  is used to obtain an explanation of an error returned by the shmat(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.

       shmid   The original shmid, exactly as passed to the shmat(2) system call.

       shmaddr The original shmaddr, exactly as passed to the shmat(2) system call.

       shmflg  The original shmflg, exactly as passed to the shmat(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, 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:
	      void *result = shmat(shmid, shmaddr, shmflg);
	      if (!result)
	      {
		  fprintf(stderr, "%s
", explain_shmat(shmid, shmaddr, shmflg));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_shmat
       const char *explain_errno_shmat(int errnum, int shmid, const void *shmaddr, int shmflg);

       The explain_errno_shmat function is used to obtain an explanation of an error returned by the shmat(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 neces-
	       sary 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.

       shmid   The original shmid, exactly as passed to the shmat(2) system call.

       shmaddr The original shmaddr, exactly as passed to the shmat(2) system call.

       shmflg  The original shmflg, exactly as passed to the shmat(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,  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:
	      void *result = shmat(shmid, shmaddr, shmflg);
	      if (!result)
	      {
		  int err = errno;
		  fprintf(stderr, "%s
", explain_errno_shmat(err, shmid, shmaddr, shmflg));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_shmat
       void explain_message_shmat(char *message, int message_size, int shmid, const void *shmaddr, int shmflg);

       The explain_message_shmat function is used to obtain an explanation of an error returned by the shmat(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 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.

       shmid   The original shmid, exactly as passed to the shmat(2) system call.

       shmaddr The original shmaddr, exactly as passed to the shmat(2) system call.

       shmflg  The original shmflg, exactly as passed to the shmat(2) system call.

       Example: This function is intended to be used in a fashion similar to the following example:
	      void *result = shmat(shmid, shmaddr, shmflg);
	      if (!result)
	      {
		  char message[3000];
		  explain_message_shmat(message, sizeof(message), shmid, shmaddr, shmflg);
		  fprintf(stderr, "%s
", message);
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_errno_shmat
       void explain_message_errno_shmat(char *message, int message_size, int errnum, int shmid, const void *shmaddr, int shmflg);

       The explain_message_errno_shmat function is used to obtain an explanation of an error returned by the shmat(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 explained and this function, because many libc functions will alter
	       the value of errno.

       shmid   The original shmid, exactly as passed to the shmat(2) system call.

       shmaddr The original shmaddr, exactly as passed to the shmat(2) system call.

       shmflg  The original shmflg, exactly as passed to the shmat(2) system call.

       Example: This function is intended to be used in a fashion similar to the following example:
	      void *result = shmat(shmid, shmaddr, shmflg);
	      if (!result)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_shmat(message, sizeof(message), err, shmid, shmaddr, shmflg);
		  fprintf(stderr, "%s
", message);
		  exit(EXIT_FAILURE);
	      }

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

SEE ALSO

       shmat(2)
	       shared memory attach

       explain_shmat_or_die(3)
	       shared memory attach and report errors

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2011 Peter Miller

																  explain_shmat(3)