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NAME

       explain_truncate - explain truncate(2) errors

SYNOPSIS

       #include <libexplain/truncate.h>
       const char *explain_truncate(const char *pathname, long long length);
       const  char  *explain_errno_truncate(int  errnum, const char *pathname,
       long long length);
       void explain_message_truncate(char *message,  int  message_size,  const
       char *pathname, long long length);
       void  explain_message_errno_truncate(char  *message,  int message_size,
       int errnum, const char *pathname, long long length);

DESCRIPTION

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

   explain_truncate
       const char *explain_truncate(const char *pathname, long long length);

       The  explain_truncate  function  is used to obtain an explanation of an
       error returned by the truncate(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 (truncate(pathname, length) < 0)
              {
                  fprintf(stderr, "%s\n", explain_truncate(pathname, length));
                  exit(EXIT_FAILURE);
              }

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

       length  The  original  length,  exactly  as  passed  to the truncate(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_truncate
       const  char  *explain_errno_truncate(int  errnum, const char *pathname,
       long long length);

       The explain_errno_truncate function is used to obtain an explanation of
       an  error  returned  by  the  truncate(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 (truncate(pathname, length) < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_truncate(err, pathname, length));
                  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.

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

       length  The original length,  exactly  as  passed  to  the  truncate(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_truncate
       void explain_message_truncate(char *message,  int  message_size,  const
       char *pathname, long long length);

       The  explain_message_truncate  function  may  be  used  to   obtain  an
       explanation of an error returned by the truncate(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 (truncate(pathname, length) < 0)
              {
                  char message[3000];
                  explain_message_truncate(message, sizeof(message), pathname, length);
                  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.

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

       length  The  original  length,  exactly  as  passed  to the truncate(2)
               system call.

   explain_message_errno_truncate
       void explain_message_errno_truncate(char  *message,  int  message_size,
       int errnum, const char *pathname, long long length);

       The  explain_message_errno_truncate  function  may be used to obtain an
       explanation of an error returned by the truncate(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 (truncate(pathname, length) < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_truncate(message, sizeof(message), err,
                      pathname, length);
                  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.

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

       length  The original length,  exactly  as  passed  to  the  truncate(2)
               system call.

SEE ALSO

       truncate(2)
               truncate a file to a specified length

       explain_truncate_or_die(3)
               truncate a file to a specified length and report errors

COPYRIGHT

       libexplain version 0.19
       Copyright (C) 2008 Peter Miller

                                                           explain_truncate(3)