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NAME

       explain_putc - explain putc(3) errors

SYNOPSIS

       #include <libexplain/putc.h>
       const char *explain_putc(int c, FILE *fp);
       const char *explain_errno_putc(int errnum, int c, FILE *fp);
       void  explain_message_putc(char *message, int message_size, int c, FILE
       *fp);
       void explain_message_errno_putc(char *message,  int  message_size,  int
       errnum, int c, FILE *fp);

DESCRIPTION

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

   explain_putc
       const char *explain_putc(int c, FILE *fp);

       The explain_putc function is used to obtain an explanation of an  error
       returned  by  the  putc(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:
              if (putc(c, fp) == EOF)
              {
                  fprintf(stderr, "%s\n", explain_putc(c, fp));
                  exit(EXIT_FAILURE);
              }

       c       The original c, exactly as passed to the putc(3) system call.

       fp      The  original fp, exactly as passed to the putc(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_putc
       const char *explain_errno_putc(int errnum, int c, FILE *fp);

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

       c       The original c, exactly as passed to the putc(3) system call.

       fp      The  original fp, exactly as passed to the putc(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_putc
       void  explain_message_putc(char *message, int message_size, int c, FILE
       *fp);

       The explain_message_putc function may be used to  obtain an explanation
       of an error returned by the putc(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:
              if (putc(c, fp) == EOF)
              {
                  char message[3000];
                  explain_message_putc(message, sizeof(message), c, 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.

       c       The original c, exactly as passed to the putc(3) system call.

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

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

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

       c       The original c, exactly as passed to the putc(3) system call.

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

SEE ALSO

       putc(3) output of characters

       explain_putc_or_die(3)
               output of characters and report errors

COPYRIGHT

       libexplain version 0.19
       Copyright (C) 2008 Peter Miller

                                                               explain_putc(3)