diff options
Diffstat (limited to 'nuttx/libc/stdio/lib_libfflush.c')
-rw-r--r-- | nuttx/libc/stdio/lib_libfflush.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/nuttx/libc/stdio/lib_libfflush.c b/nuttx/libc/stdio/lib_libfflush.c new file mode 100644 index 000000000..f2f0cfe14 --- /dev/null +++ b/nuttx/libc/stdio/lib_libfflush.c @@ -0,0 +1,202 @@ +/**************************************************************************** + * libc/stdio/lib_libfflush.c + * + * Copyright (C) 2007-2008, 2011-2012 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + +/**************************************************************************** + * Compilation Switches + ****************************************************************************/ + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> + +#include <sys/types.h> +#include <stdbool.h> +#include <unistd.h> +#include <fcntl.h> +#include <errno.h> + +#include <nuttx/fs/fs.h> + +#include "lib_internal.h" + +/**************************************************************************** + * Definitions + ****************************************************************************/ + +/**************************************************************************** + * Private Type Declarations + ****************************************************************************/ + +/**************************************************************************** + * Private Function Prototypes + ****************************************************************************/ + +/**************************************************************************** + * Global Constant Data + ****************************************************************************/ + +/**************************************************************************** + * Global Variables + ****************************************************************************/ + +/**************************************************************************** + * Private Constant Data + ****************************************************************************/ + +/**************************************************************************** + * Private Variables + ****************************************************************************/ + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: lib_fflush + * + * Description: + * The function lib_fflush() forces a write of all user-space buffered data for + * the given output or update stream via the stream's underlying write + * function. The open status of the stream is unaffected. + * + * Parmeters: + * stream - the stream to flush + * bforce - flush must be complete. + * + * Return: + * A negated errno value on failure, otherwise the number of bytes remaining + * in the buffer. + * + ****************************************************************************/ + +ssize_t lib_fflush(FAR FILE *stream, bool bforce) +{ +#if CONFIG_STDIO_BUFFER_SIZE > 0 + FAR const unsigned char *src; + ssize_t bytes_written; + ssize_t nbuffer; + + /* Return EBADF if the file is not opened for writing */ + + if (stream->fs_filedes < 0 || (stream->fs_oflags & O_WROK) == 0) + { + return -EBADF; + } + + /* Make sure that we have exclusive access to the stream */ + + lib_take_semaphore(stream); + + /* Make sure that the buffer holds valid data */ + + if (stream->fs_bufpos != stream->fs_bufstart) + { + /* Make sure that the buffer holds buffered write data. We do not + * support concurrent read/write buffer usage. + */ + + if (stream->fs_bufread != stream->fs_bufstart) + { + /* The buffer holds read data... just return zero meaning "no bytes + * remaining in the buffer." + */ + + lib_give_semaphore(stream); + return 0; + } + + /* How many bytes of write data are used in the buffer now */ + + nbuffer = stream->fs_bufpos - stream->fs_bufstart; + + /* Try to write that amount */ + + src = stream->fs_bufstart; + do + { + /* Perform the write */ + + bytes_written = write(stream->fs_filedes, src, nbuffer); + if (bytes_written < 0) + { + /* Write failed. The cause of the failure is in 'errno'. + * returned the negated errno value. + */ + + lib_give_semaphore(stream); + return -get_errno(); + } + + /* Handle partial writes. fflush() must either return with + * an error condition or with the data successfully flushed + * from the buffer. + */ + + src += bytes_written; + nbuffer -= bytes_written; + } + while (bforce && nbuffer > 0); + + /* Reset the buffer position to the beginning of the buffer */ + + stream->fs_bufpos = stream->fs_bufstart; + + /* For the case of an incomplete write, nbuffer will be non-zero + * It will hold the number of bytes that were not written. + * Move the data down in the buffer to handle this (rare) case + */ + + while (nbuffer) + { + *stream->fs_bufpos++ = *src++; + --nbuffer; + } + } + + /* Restore normal access to the stream and return the number of bytes + * remaining in the buffer. + */ + + lib_give_semaphore(stream); + return stream->fs_bufpos - stream->fs_bufstart; +#else + /* Return no bytes remaining in the buffer */ + + return 0; +#endif +} + |