Implementation status: partially implemented


#include <stdio.h>

int fclose(FILE *stream);


The function closes the stream.


stream - the stream to be closed.

The fclose() function causes the stream pointed to by stream to be flushed and the associated file to be closed. Any unwritten buffered data for the stream is written to the file; any unread buffered data is discarded. Whether or not the call succeeds, the stream is disassociated from the file and any buffer set by the setbuf() or setvbuf() function are disassociated from the stream. If the associated buffer was automatically allocated, it is deallocated.

If the file is not already at EOF, and the file is one capable of seeking, the file offset of the underlying open file description is set to the file position of the stream if the stream is the active handle to the underlying file description.

The fclose() function marks for update the last data modification and last file status change timestamps of the underlying file, if the stream was writable, and if buffered data remains that has not yet been written to the file. The fclose() function performs the equivalent of a close() on the file descriptor that is associated with the stream pointed to by stream.

After the call to fclose(), any use of stream results in undefined behavior.

Return value

Upon successful completion, fclose() returns 0. Otherwise, EOF is returned and errno set to indicate the error.


[EAGAIN] The O_NONBLOCK flag is set for the file descriptor underlying stream and the thread would be delayed in the write operation.
[EBADF] The file descriptor underlying stream is not valid.
[EFBIG] An attempt was made to write a file that exceeds the maximum file size or
An attempt was made to write a file that exceeds the file size limit of the process or
The file is a regular file and an attempt was made to write at or beyond the offset maximum associated with the corresponding stream.
[EINTR] The fclose() function was interrupted by a signal.
[EIO] The process is a member of a background process group attempting to write to its controlling terminal, TOSTOP is set, the calling thread is not blocking SIGTTOU, the process is not ignoring SIGTTOU, and the process group of the process is orphaned.
[ENOMEM] The underlying stream was created by open_memstream() or open_wmemstream() and insufficient memory is available.
[ENOSPC] There was no free space remaining on the device containing the file or in the buffer used by the fmemopen() function.
[EPIPE] An attempt is made to write to a pipe or FIFO that is not open for reading by any process. A SIGPIPE signal is also sent to the thread.
[ENXIO] A request was made of a nonexistent device, or the request was outside the capabilities of the device.

Implementation tasks

  • Implement error detection for errors described above.