NAME

       explain_setbuf - explain setbuf(3) errors

SYNOPSIS

       #include <libexplain/setbuf.h>
       const char *explain_setbuf(FILE *fp, char *data);
       const char *explain_errno_setbuf(int errnum, FILE *fp, char *data);
       void explain_message_setbuf(char *message, int message_size, FILE *fp, char *data);
       void explain_message_errno_setbuf(char *message, int message_size, int errnum, FILE *fp, char *data);

DESCRIPTION

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

   explain_setbuf
       const char *explain_setbuf(FILE *fp, char *data);

       The explain_setbuf function is used to obtain an explanation of an error returned by the setbuf(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.

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

       data    The original data, exactly as passed to the setbuf(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:
              errno = 0;
              void result = setbuf(fp, data);
              if (result < 0 && errno != 0)
              {
                  fprintf(stderr, "%s\n", explain_setbuf(fp, data));
                  exit(EXIT_FAILURE);
              }

       The above code example is available pre‐packaged as the explain_setbuf_or_die(3) function.

   explain_errno_setbuf
       const char *explain_errno_setbuf(int errnum, FILE *fp, char *data);

       The explain_errno_setbuf function is used to obtain an explanation of an error returned by the  setbuf(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.

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

       data    The original data, exactly as passed to the setbuf(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:
              errno = 0;
              void result = setbuf(fp, data);
              if (result < 0 && errno != 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_setbuf(err, fp, data));
                  exit(EXIT_FAILURE);
              }

       The above code example is available pre‐packaged as the explain_setbuf_or_die(3) function.

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

       The explain_message_setbuf function is used to  obtain  an  explanation  of  an  error  returned  by  the
       setbuf(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.

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

       data    The original data, exactly as passed to the setbuf(3) system call.

       Example: This function is intended to be used in a fashion similar to the following example:
              errno = 0;
              void result = setbuf(fp, data);
              if (result < 0 && errno != 0)
              {
                  char message[3000];
                  explain_message_setbuf(message, sizeof(message), fp, data);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The above code example is available pre‐packaged as the explain_setbuf_or_die(3) function.

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

       The explain_message_errno_setbuf function is used to obtain an explanation of an error  returned  by  the
       setbuf(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.

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

       data    The original data, exactly as passed to the setbuf(3) system call.

       Example: This function is intended to be used in a fashion similar to the following example:
              errno = 0;
              void result = setbuf(fp, data);
              if (result < 0 && errno != 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_setbuf(message, sizeof(message), err, fp, data);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The above code example is available pre‐packaged as the explain_setbuf_or_die(3) function.

SEE ALSO

       setbuf(3)
               set stream buffer

       explain_setbuf_or_die(3)
               set stream buffer and report errors

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2010 Peter Miller

                                                                                               explain_setbuf(3)