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NAME

       explain_getc - explain getc(3) errors

SYNOPSIS

       #include <libexplain/getc.h>
       const char *explain_getc(FILE *fp);
       const char *explain_errno_getc(int errnum, FILE *fp);
       void explain_message_getc(char *message, int message_size, FILE *fp);
       void  explain_message_errno_getc(char  *message,  int message_size, int
       errnum, FILE *fp);

DESCRIPTION

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

   explain_getc
       const char *explain_getc(FILE *fp);

       The  explain_getc function is used to obtain an explanation of an error
       returned by the getc(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.

       This  function  is  intended  to  be  used  in a fashion similar to the
       following example:
              int c = getc(fp);
              if (c == EOF && ferror(fp))
              {
                  fprintf(stderr, "%s\n", explain_getc(fp));
                  exit(EXIT_FAILURE);
              }

       fp      The original fp, exactly as passed to the getc(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.

   explain_errno_getc
       const char *explain_errno_getc(int errnum, FILE *fp);

       The explain_errno_getc function is used to obtain an explanation of  an
       error  returned by the getc(3) 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:
              int c = getc(fp);
              if (c == EOF && ferror(fp))
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_getc(err, fp));
                  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.

       fp      The original fp, exactly as passed to the getc(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.

   explain_message_getc
       void explain_message_getc(char *message, int message_size, FILE *fp);

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

       This function is intended to be  used  in  a  fashion  similar  to  the
       following example:
              int c = getc(fp);
              if (c == EOF && ferror(fp))
              {
                  char message[3000];
                  explain_message_getc(message, sizeof(message), fp);
                  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.

       fp      The original fp, exactly as passed to the getc(3) system  call.

   explain_message_errno_getc
       void  explain_message_errno_getc(char  *message,  int message_size, int
       errnum, FILE *fp);

       The explain_message_errno_getc  function  may  be  used  to  obtain  an
       explanation of an error returned by the getc(3) 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:
              int c = getc(fp);
              if (c == EOF && ferror(fp))
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_getc(message, sizeof(message), err, fp);
                  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.

       fp      The original fp, exactly as passed to the getc(3) system  call.

SEE ALSO

       getc(3) input of characters

       explain_getc_or_die(3)
               input of characters and report errors

COPYRIGHT

       libexplain version 0.19
       Copyright (C) 2008 Peter Miller

                                                               explain_getc(3)