/**************************************************************************** * libc/stdio/lib_setvbuf.c * * Copyright (C) 2017 Gregory Nutt. All rights reserved. * Author: Alan Carvalho de Assis * Gregory Nutt * * This code is based on Newlib implementation. * * 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 will 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. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include "libc.h" /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: setvbuf * * Description: * The setvbuf() function may be used after the stream pointed to by * stream is associated with an open file but before any other operation * (other than an unsuccessful call to setvbuf()) is performed on the * stream. The argument type determines how stream will be buffered, as * follows: * * _IOFBF - Will cause input/output to be fully buffered. * _IOLBF - Will cause input/output to be line buffered. * _IONBF - Will cause input/output to be unbuffered. * * If buf is not a null pointer, the array it points to may be used instead * of a buffer allocated by setvbuf() and the argument size specifies the size * of the array; otherwise, size may determine the size of a buffer allocated * by the setvbuf() function. The contents of the array at any time are * unspecified. * * REVISIT: This initial version of setvbuf has some limitations and not * all features features required by the specification are available. * Specifically, this current implementation cannot support sisabling * stream buffering if CONFIG_STDIO_BUFFER_SIZE > 0 * * Parmeters: * stream - the stream to flush * buffer - the user allocate buffer. If NULL, will allocates a buffer of * specified size * mode - specifies a mode for file buffering * size - size of buffer * * Return: * Upon successful completion, setvbuf() will return 0. Otherwise, it will * return a non-zero value if an invalid value is given for type or if the * request cannot be honored, [CX] and may set errno to indicate the error * ****************************************************************************/ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size) { #if CONFIG_STDIO_BUFFER_SIZE > 0 uint8_t flags; int errcode; int ret = OK; /* Verify arguments */ if (mode != _IOFBF && mode != _IOLBF && mode != _IONBF) { errcode = EINVAL; goto errout; } /* Make sure that the size argument agrees with the mode */ if (((mode == _IOFBF || mode == _IOLBF) && size == 0) || (mode == _IONBF && size > 0)) { errcode = EINVAL; goto errout; } /* Make sure that the buffer argument agrees with mode */ if (mode == _IONBF && buffer != NULL) { errcode = EINVAL; goto errout; } /* Make sure that the buffer and size argeuments agree */ if (buffer != NULL && size == 0) { errcode = EINVAL; goto errout; } #if 1 /* REVISIT: _IONBF not yet supported */ /* Not all features are be available. Without some additional logic, * we cannot disable buffering if CONFIG_STDIO_BUFFER_SIZE > 0 */ if (mode == _IONBF) { errcode = ENOSYS; goto errout; } #endif /* Make sure that we have exclusive access to the stream */ lib_take_semaphore(stream); /* setvbuf() may only be called AFTER the file has been opened and BEFORE * any operations have been performed on the string. */ /* Return EBADF if the file is not open */ if (stream->fs_fd < 0) { errcode = EBADF; goto errout_with_semaphore; } /* Return EBUSY if operations have already been performed on the buffer. * Here we really only verify that there is no valid data in the existing * buffer. */ if (stream->fs_bufpos != stream->fs_bufstart) { errcode = EBUSY; goto errout_with_semaphore; } /* Initialize by clearing related flags. We try to avoid any permanent * changes to the stream structure until we know that we will be * successful. */ #if 1 /* REVISIT: _IONBF not yet supported */ flags = stream->fs_flags & ~(__FS_FLAG_LBF | __FS_FLAG_UBF); #else flags = stream->fs_flags & ~(__FS_FLAG_LBF | __FS_FLAG_NBF | __FS_FLAG_UBF); #endif /* Allocate a new buffer if one is needed. We have already verified that: * * If a buffer is needed, then size > 0 * If a buffer is NOT needed, then buffer is NULL * If buffer != NULL, then size > 0 * * That simplifies the following check: */ #if 0 /* REVISIT: _IONBF not yet supported */ if (size > 0) #else DEBUGASSERT(size > 0); #endif { FAR unsigned char *newbuf; /* A buffer is needed. Did the caller provide the buffer memory? */ DEBUGASSERT(mode == _IOFBF || mode == _IOLBF); if (buffer != NULL) { newbuf = (FAR unsigned char *)buffer; /* Indicate that we have an I/O buffer managed by the caller of * setvbuf. */ flags |= __FS_FLAG_UBF; } else { newbuf = (FAR unsigned char *)lib_malloc(size); if (newbuf == NULL) { errcode = ENOMEM; goto errout_with_semaphore; } } /* Do not release the previous buffer if it was allocated by the user * on a previous call to setvbuf(). */ if ((stream->fs_flags & __FS_FLAG_UBF) != 0) { lib_free(stream->fs_bufstart); } /* Use the new buffer */ stream->fs_bufstart = newbuf; stream->fs_bufend = newbuf; stream->fs_bufpos = newbuf; stream->fs_bufread = newbuf; /* Check for line buffering */ if (mode == _IOLBF) { flags |= __FS_FLAG_LBF; } } #if 0 /* REVISIT: _IONBF not yet supported */ else { /* No buffer needed... We must be performing unbuffered I/O */ DEBUGASSERT(mode == _IONBF); flags |= __FS_FLAG_NBF; } #endif /* Update the stream flags and return success */ stream->fs_flags = flags; lib_give_semaphore(stream); return OK; errout_with_semaphore: lib_give_semaphore(stream); errout: set_errno(errcode); return ERROR; #else /* Return that setvbuf() is not supported */ set_errno(ENOSYS); return ERROR; #endif }