size_t __fbufsize(FILE *stream);
size_t __fpending(FILE *stream);
int __flbf(FILE *stream);
int __freadable(FILE *stream);
int __fwritable(FILE *stream);
int __freading(FILE *stream);
int __fwriting(FILE *stream);
int __fsetlocking(FILE *stream, int type);
void _flushlbf(void);
void __fpurge(FILE *stream);
The __fbufsize() function returns the size of the buffer currently used by the given stream.
The __fpending() function returns the number of bytes in the output buffer. For wide-oriented streams the unit is wide characters. This function is undefined on buffers in reading mode, or opened read-only.
The __flbf() function returns a non-zero value if the stream is line-buffered, and zero otherwise.
The __freadable() function returns a non-zero value if the stream allows reading, and zero otherwise.
The __fwritable() function returns a non-zero value if the stream allows writing, and zero otherwise.
The __freading() function returns a non-zero value if the stream is read-only, or if the last operation on the stream was a read operation, and zero otherwise.
The __fwriting() function returns a non-zero value if the stream is write-only (or append-only), or if the last operation on the stream was a write operation, and zero otherwise.
The __fsetlocking() function can be used to select the desired type of locking on the stream. It returns the current type. The type argument can take the following three values:
The _flushlbf() function flushes all line-buffered streams. (Presumably so that output to a terminal is forced out, say before reading keyboard input.)
The __fpurge() function discards the contents of the stream's buffer.