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NAME

       explain_fstat - explain fstat(2) errors

SYNOPSIS

       #include <libexplain/fstat.h>
       const char *explain_fstat(int fildes, struct stat *buf);
       const  char  *explain_errno_fstat(int  errnum,  int fildes, struct stat
       *buf);
       void explain_message_fstat(char *message, int message_size, int fildes,
       struct stat *buf);
       void  explain_message_errno_fstat(char  *message, int message_size, int
       errnum, int fildes, struct stat *buf);

DESCRIPTION

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

   explain_fstat
       const char *explain_fstat(int fildes, struct stat *buf);

       The explain_fstat function is used to obtain an explanation of an error
       returned by the fstat(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.

       This  function  is  intended  to  be  used  in a fashion similar to the
       following example:
              if (fstat(fildes, buf) < 0)
              {
                  fprintf(stderr, "%s\n", explain_fstat(fildes, buf));
                  exit(EXIT_FAILURE);
              }

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

       buf     The  original  buf,  exactly  as  passed to the fstat(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.

   explain_errno_fstat
       const  char  *explain_errno_fstat(int  errnum,  int fildes, struct stat
       *buf);

       The explain_errno_fstat function is used to obtain an explanation of an
       error returned by the fstat(2) system call.  The least the message will
       contain is the value of strerror(errnum), but usually it will  do  much
       better, and indicate the underlying cause in more detail.

       This  function  is  intended  to  be  used  in a fashion similar to the
       following example:
              if (fstat(fildes, buf) < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_fstat(err, fildes, buf));
                  exit(EXIT_FAILURE);
              }

       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  fstat(2)  system
               call.

       buf     The  original  buf,  exactly  as  passed to the fstat(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.

   explain_message_fstat
       void explain_message_fstat(char *message, int message_size, int fildes,
       struct stat *buf);

       The  explain_message_fstat  function  may  be  used   to    obtain   an
       explanation  of  an  error  returned  by the fstat(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.

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

       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 fstat(2) system
               call.

       buf     The original buf, exactly as  passed  to  the  fstat(2)  system
               call.

   explain_message_errno_fstat
       void  explain_message_errno_fstat(char  *message, int message_size, int
       errnum, int fildes, struct stat *buf);

       The explain_message_errno_fstat function  may  be  used  to  obtain  an
       explanation  of  an  error  returned  by the fstat(2) system call.  The
       least the message will contain is the value  of  strerror(errnum),  but
       usually  it  will  do much better, and indicate the underlying cause in
       more detail.

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

       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  fstat(2)  system
               call.

       buf     The  original  buf,  exactly  as  passed to the fstat(2) system
               call.

SEE ALSO

       fstat(2)
               get file status

       explain_fstat_or_die(3)
               get file status and report errors

COPYRIGHT

       libexplain version 0.19
       Copyright (C) 2008 Peter Miller

                                                              explain_fstat(3)