/**************************************************************************** * libs/libc/stdio/lib_libfread.c * * Copyright (C) 2007-2009, 2011-2014, 2017 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include "libc.h" /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: lib_fread ****************************************************************************/ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream) { FAR unsigned char *dest = (FAR unsigned char*)ptr; ssize_t bytes_read; size_t remaining = count; #ifndef CONFIG_STDIO_DISABLE_BUFFERING int ret; #endif /* Make sure that reading from this stream is allowed */ if (!stream || (stream->fs_oflags & O_RDOK) == 0) { set_errno(EBADF); bytes_read = -1; } else { /* The stream must be stable until we complete the read */ lib_take_semaphore(stream); #if CONFIG_NUNGET_CHARS > 0 /* First, re-read any previously ungotten characters */ while (stream->fs_nungotten > 0 && remaining > 0) { /* Decrement the count of ungotten bytes to get an index */ stream->fs_nungotten--; /* Return the last ungotten byte */ *dest++ = stream->fs_ungotten[stream->fs_nungotten]; /* That's one less byte that we have to read */ remaining--; } #endif #ifndef CONFIG_STDIO_DISABLE_BUFFERING /* Is there an I/O buffer? */ if (stream->fs_bufstart != NULL) { /* If the buffer is currently being used for write access, then * flush all of the buffered write data. We do not support concurrent * buffered read/write access. */ ret = lib_wrflush(stream); if (ret < 0) { lib_give_semaphore(stream); return ret; } /* Now get any other needed chars from the buffer or the file. */ while (remaining > 0) { /* Is there readable data in the buffer? */ while (remaining > 0 && stream->fs_bufpos < stream->fs_bufread) { /* Yes, copy a byte into the user buffer */ *dest++ = *stream->fs_bufpos++; remaining--; } /* The buffer is empty OR we have already supplied the number of * bytes requested in the read. Check if we need to read * more from the file. */ if (remaining > 0) { size_t buffer_available; /* We need to read more data into the buffer from the file */ /* Mark the buffer empty */ stream->fs_bufpos = stream->fs_bufread = stream->fs_bufstart; /* How much space is available in the buffer? */ buffer_available = stream->fs_bufend - stream->fs_bufread; /* Will the number of bytes that we need to read fit into * the buffer space that is available? If the read size is * larger than the buffer, then read some of the data * directly into the user's buffer. */ if (remaining > buffer_available) { bytes_read = _NX_READ(stream->fs_fd, dest, remaining); if (bytes_read < 0) { /* An error occurred on the read. */ _NX_SETERRNO(bytes_read); goto errout_with_errno; } else if (bytes_read == 0) { /* We are at the end of the file. But we may already * have buffered data. In that case, we will report * the EOF indication later. */ goto shortread; } else { /* Some (perhaps all) bytes were read. Adjust the dest * pointer and remaining bytes to be read. */ DEBUGASSERT(bytes_read <= remaining); dest += bytes_read; remaining -= bytes_read; } } else { /* The number of bytes required to satisfy the read * is less than or equal to the size of the buffer * space that we have left. Read as much as we can * into the buffer. */ bytes_read = _NX_READ(stream->fs_fd, stream->fs_bufread, buffer_available); if (bytes_read < 0) { /* An error occurred on the read. The error code is * in the 'errno' variable. */ _NX_SETERRNO(bytes_read); goto errout_with_errno; } else if (bytes_read == 0) { /* We are at the end of the file. But we may already * have buffered data. In that case, we will report * the EOF indication later. */ goto shortread; } else { /* Some (perhaps all) bytes were read */ stream->fs_bufread += bytes_read; } } } } } else #endif { /* Now get any other needed chars from the file. */ while (remaining > 0) { bytes_read = _NX_READ(stream->fs_fd, dest, remaining); if (bytes_read < 0) { /* An error occurred on the read. The error code is * in the 'errno' variable. */ _NX_SETERRNO(bytes_read); goto errout_with_errno; } else if (bytes_read == 0) { /* We are at the end of the file. But we may already * have buffered data. In that case, we will report * the EOF indication later. */ break; } else { DEBUGASSERT(bytes_read <= remaining); dest += bytes_read; remaining -= bytes_read; } } } #ifndef CONFIG_STDIO_DISABLE_BUFFERING /* Here after a successful (but perhaps short) read. A short read can * only occur is read() returns 0 (end-of-file). */ shortread: #endif /* Set or clear the EOF indicator. If we get here because of a * short read and the total number of bytes read is zero, then * we must be at the end-of-file. */ if (remaining == 0) { stream->fs_flags &= ~__FS_FLAG_EOF; } else { stream->fs_flags |= __FS_FLAG_EOF; } lib_give_semaphore(stream); } return count - remaining; /* Error exits */ errout_with_errno: stream->fs_flags |= __FS_FLAG_ERROR; lib_give_semaphore(stream); return -get_errno(); }