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NAME

       explain_putchar - explain putchar(3) errors

SYNOPSIS

       #include <libexplain/putchar.h>
       const char *explain_putchar(int c);
       const char *explain_errno_putchar(int errnum, int c);
       void explain_message_putchar(char *message, int message_size, int c);
       void explain_message_errno_putchar(char *message, int message_size, int
       errnum, int c);

DESCRIPTION

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

   explain_putchar
       const char *explain_putchar(int c);

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

       c       The original c, exactly as  passed  to  the  putchar(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_putchar
       const char *explain_errno_putchar(int errnum, int c);

       The explain_errno_putchar function is used to obtain an explanation  of
       an error returned by the putchar(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 (putchar(c) == EOF)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_putchar(err, c));
                  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  putchar(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_putchar
       void explain_message_putchar(char *message, int message_size, int c);

       The  explain_message_putchar  function  may  be  used  to   obtain   an
       explanation  of  an  error returned by the putchar(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 (putchar(c) == EOF)
              {
                  char message[3000];
                  explain_message_putchar(message, sizeof(message), c);
                  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 putchar(3) system
               call.

   explain_message_errno_putchar
       void explain_message_errno_putchar(char *message, int message_size, int
       errnum, int c);

       The  explain_message_errno_putchar  function  may  be used to obtain an
       explanation of an error returned by the putchar(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 (putchar(c) == EOF)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_putchar(message, sizeof(message), err, c);
                  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 putchar(3) system
               call.

SEE ALSO

       putchar(3)
               output of characters

       explain_putchar_or_die(3)
               output of characters and report errors

COPYRIGHT

       libexplain version 0.19
       Copyright (C) 2008 Peter Miller

                                                            explain_putchar(3)