Provided by: explain_0.52.D002-1_amd64 bug

NAME

       explain_flock - explain flock(2) errors

SYNOPSIS

       #include <libexplain/flock.h>
       const char *explain_flock(int fildes, int command);
       const char *explain_errno_flock(int errnum, int fildes, int command);
       void explain_message_flock(char *message, int message_size, int fildes, int command);
       void explain_message_errno_flock(char *message, int message_size, int errnum, int fildes,
       int command);

DESCRIPTION

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

   explain_flock
       const char *explain_flock(int fildes, int command);

       The  explain_flock  function  is used to obtain an explanation of an error returned by the
       flock(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.

       fildes  The original fildes, exactly as passed to the flock(2) system call.

       command The original command, exactly as passed to the flock(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:
              if (flock(fildes, command) < 0)
              {
                  fprintf(stderr, "%s\n", explain_flock(fildes, command));
                  exit(EXIT_FAILURE);
              }

       The above code example is available pre‐packaged as the explain_flock_or_die(3) function.

   explain_errno_flock
       const char *explain_errno_flock(int errnum, int fildes, int command);

       The explain_errno_flock function is used to obtain an explanation of an error returned  by
       the   flock(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.

       fildes  The original fildes, exactly as passed to the flock(2) system call.

       command The original command, exactly as passed to the flock(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:
              if (flock(fildes, command) < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_flock(err, fildes, command));
                  exit(EXIT_FAILURE);
              }

       The above code example is available pre‐packaged as the explain_flock_or_die(3) function.

   explain_message_flock
       void explain_message_flock(char *message, int message_size, int fildes, int command);

       The  explain_message_flock  function is used to obtain an explanation of an error returned
       by the flock(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.

       fildes  The original fildes, exactly as passed to the flock(2) system call.

       command The original command, exactly as passed to the flock(2) system call.

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

       The above code example is available pre‐packaged as the explain_flock_or_die(3) function.

   explain_message_errno_flock
       void explain_message_errno_flock(char *message, int message_size, int errnum, int fildes,
       int command);

       The  explain_message_errno_flock  function  is  used  to obtain an explanation of an error
       returned by the flock(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 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.

       fildes  The original fildes, exactly as passed to the flock(2) system call.

       command The original command, exactly as passed to the flock(2) system call.

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

       The above code example is available pre‐packaged as the explain_flock_or_die(3) function.

SEE ALSO

       flock(2)
               apply or remove an advisory lock on an open file

       explain_flock_or_die(3)
               apply or remove an advisory lock on an open file and report errors

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2009 Peter Miller

                                                                                 explain_flock(3)