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NAME

       explain_strtoul - explain strtoul(3) errors

SYNOPSIS

       #include <libexplain/strtoul.h>
       const char *explain_strtoul(const char *nptr, char **endptr, int base);
       const char *explain_errno_strtoul(int errnum, const char *nptr, char
       **endptr, int base);
       void explain_message_strtoul(char *message, int message_size, const
       char *nptr, char **endptr, int base);
       void explain_message_errno_strtoul(char *message, int message_size, int
       errnum, const char *nptr, char **endptr, int base);

DESCRIPTION

       These  functions may be used to obtain explanations for errors returned
       by the strtoul(3) system call.

   explain_strtoul
       const char *explain_strtoul(const char *nptr, char **endptr, int base);

       The  explain_strtoul  function  is  used to obtain an explanation of an
       error returned by the strtoul(3) 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.

       nptr    The  original  nptr, exactly as passed to the strtoul(3) system
               call.

       endptr  The original endptr, exactly as passed to the strtoul(3) system
               call.

       base    The  original  base, exactly as passed to the strtoul(3) 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:
              unsigned long result = strtoul(nptr, endptr, base);
              if (result < 0)
              {
                  fprintf(stderr, "%s\n", explain_strtoul(nptr, endptr,
                  base));
                  exit(EXIT_FAILURE);
              }

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

   explain_errno_strtoul
       const char *explain_errno_strtoul(int errnum, const char *nptr, char
       **endptr, int base);

       The  explain_errno_strtoul function is used to obtain an explanation of
       an error returned by the strtoul(3) 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.

       nptr    The original nptr, exactly as passed to the  strtoul(3)  system
               call.

       endptr  The original endptr, exactly as passed to the strtoul(3) system
               call.

       base    The original base, exactly as passed to the  strtoul(3)  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:
              unsigned long result = strtoul(nptr, endptr, base);
              if (result < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_strtoul(err, nptr,
                  endptr, base));
                  exit(EXIT_FAILURE);
              }

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

   explain_message_strtoul
       void explain_message_strtoul(char *message, int message_size, const
       char *nptr, char **endptr, int base);

       The explain_message_strtoul function is used to obtain  an  explanation
       of  an  error  returned  by  the  strtoul(3) 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.

       nptr    The original nptr, exactly as passed to the  strtoul(3)  system
               call.

       endptr  The original endptr, exactly as passed to the strtoul(3) system
               call.

       base    The original base, exactly as passed to the  strtoul(3)  system
               call.

       Example:  This  function is intended to be used in a fashion similar to
       the following example:
              unsigned long result = strtoul(nptr, endptr, base);
              if (result < 0)
              {
                  char message[3000];
                  explain_message_strtoul(message, sizeof(message), nptr,
                  endptr, base);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

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

   explain_message_errno_strtoul
       void explain_message_errno_strtoul(char *message, int message_size, int
       errnum, const char *nptr, char **endptr, int base);

       The   explain_message_errno_strtoul  function  is  used  to  obtain  an
       explanation of an error returned by the  strtoul(3)  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.

       nptr    The original nptr, exactly as passed to the  strtoul(3)  system
               call.

       endptr  The original endptr, exactly as passed to the strtoul(3) system
               call.

       base    The original base, exactly as passed to the  strtoul(3)  system
               call.

       Example:  This  function is intended to be used in a fashion similar to
       the following example:
              unsigned long result = strtoul(nptr, endptr, base);
              if (result < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_strtoul(message, sizeof(message), err,
                  nptr, endptr, base);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

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

SEE ALSO

       strtoul(3)
               convert a string to an unsigned long integer

       explain_strtoul_or_die(3)
               convert a string to an unsigned long integer and report errors

COPYRIGHT

       libexplain version 0.19
       Copyright (C) 2009 Peter Miller

                                                            explain_strtoul(3)