Provided by: libexplain-dev_1.4.D001-7_amd64 bug

NAME

       explain_openat - explain openat(2) errors

SYNOPSIS

       #include <libexplain/openat.h>
       const char *explain_openat(int fildes, const char *pathname, int flags, mode_t mode);
       const char *explain_errno_openat(int errnum, int fildes, const char *pathname, int flags,
       mode_t mode);
       void explain_message_openat(char *message, int message_size, int fildes, const char
       *pathname, int flags, mode_t mode);
       void explain_message_errno_openat(char *message, int message_size, int errnum, int fildes,
       const char *pathname, int flags, mode_t mode);

DESCRIPTION

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

   explain_openat
       const char *explain_openat(int fildes, const char *pathname, int flags, mode_t mode);

       The  explain_openat  function is used to obtain an explanation of an error returned by the
       openat(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 openat(2) system call.

       pathname
               The original pathname, exactly as passed to the openat(2) system call.

       flags   The original flags, exactly as passed to the openat(2) system call.

       mode    The original mode, exactly as passed to the openat(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:
              int result = openat(fildes, pathname, flags, mode);
              if (result < 0)
              {
                  fprintf(stderr, "%s\n", explain_openat(fildes, pathname, flags, mode));
                  exit(EXIT_FAILURE);
              }

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

   explain_errno_openat
       const char *explain_errno_openat(int errnum, int fildes, const char *pathname, int flags,
       mode_t mode);

       The explain_errno_openat function is used to obtain an explanation of an error returned by
       the  openat(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 openat(2) system call.

       pathname
               The original pathname, exactly as passed to the openat(2) system call.

       flags   The original flags, exactly as passed to the openat(2) system call.

       mode    The original mode, exactly as passed to the openat(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:
              int result = openat(fildes, pathname, flags, mode);
              if (result < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_openat(err, fildes, pathname, flags,
                  mode));
                  exit(EXIT_FAILURE);
              }

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

   explain_message_openat
       void explain_message_openat(char *message, int message_size, int fildes, const char
       *pathname, int flags, mode_t mode);

       The explain_message_openat function is used to obtain an explanation of an error  returned
       by  the  openat(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 openat(2) system call.

       pathname
               The original pathname, exactly as passed to the openat(2) system call.

       flags   The original flags, exactly as passed to the openat(2) system call.

       mode    The original mode, exactly as passed to the openat(2) system call.

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

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

   explain_message_errno_openat
       void explain_message_errno_openat(char *message, int message_size, int errnum, int fildes,
       const char *pathname, int flags, mode_t mode);

       The  explain_message_errno_openat  function  is  used to obtain an explanation of an error
       returned by the openat(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 openat(2) system call.

       pathname
               The original pathname, exactly as passed to the openat(2) system call.

       flags   The original flags, exactly as passed to the openat(2) system call.

       mode    The original mode, exactly as passed to the openat(2) system call.

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

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

SEE ALSO

       openat(2)
               open a file relative to a directory file descriptor

       explain_openat_or_die(3)
               open a file relative to a directory file descriptor and report errors

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2013 Peter Miller

                                                                                explain_openat(3)