| /**************************************************************************** |
| * lib/lib_libfread.c |
| * |
| * Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved. |
| * Author: Gregory Nutt <spudmonkey@racsa.co.cr> |
| * |
| * 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> /* for CONFIG_STDIO_BUFFER_SIZE */ |
| #include <stdio.h> |
| #include <unistd.h> |
| #include <string.h> |
| #include <fcntl.h> |
| #include <errno.h> |
| #include "lib_internal.h" |
| |
| /**************************************************************************** |
| * Definitions |
| ****************************************************************************/ |
| |
| /**************************************************************************** |
| * Private Type Declarations |
| ****************************************************************************/ |
| |
| /**************************************************************************** |
| * Private Function Prototypes |
| ****************************************************************************/ |
| |
| /**************************************************************************** |
| * Global Constant Data |
| ****************************************************************************/ |
| |
| /**************************************************************************** |
| * Global Variables |
| ****************************************************************************/ |
| |
| /**************************************************************************** |
| * Private Constant Data |
| ****************************************************************************/ |
| |
| /**************************************************************************** |
| * Private Variables |
| ****************************************************************************/ |
| |
| /**************************************************************************** |
| * Global Functions |
| ****************************************************************************/ |
| |
| /**************************************************************************** |
| * lib_fread |
| ****************************************************************************/ |
| |
| ssize_t lib_fread(void *ptr, size_t count, FILE *stream) |
| { |
| unsigned char *dest = (unsigned char*)ptr; |
| ssize_t bytes_read; |
| |
| /* Make sure that reading from this stream is allowed */ |
| |
| if (!stream || (stream->fs_oflags & O_RDOK) == 0) |
| { |
| *get_errno_ptr() = 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) && (count > 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 */ |
| |
| count--; |
| } |
| #endif |
| |
| #if CONFIG_STDIO_BUFFER_SIZE > 0 |
| /* 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. |
| */ |
| |
| if (lib_wrflush(stream) != 0) |
| { |
| return ERROR; |
| } |
| |
| /* Now get any other needed chars from the buffer or the file. */ |
| |
| while (count > 0) |
| { |
| /* Is there readable data in the buffer? */ |
| |
| while ((count > 0) && (stream->fs_bufpos < stream->fs_bufread)) |
| { |
| /* Yes, copy a byte into the user buffer */ |
| |
| *dest++ = *stream->fs_bufpos++; |
| count--; |
| } |
| |
| /* 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 (count > 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 (count > buffer_available) |
| { |
| bytes_read = read(stream->fs_filedes, dest, count); |
| if (bytes_read < 0) |
| { |
| /* An error occurred on the read */ |
| |
| goto err_out; |
| } |
| else if (bytes_read == 0) |
| { |
| /* We are at the end of the file */ |
| |
| goto short_read; |
| } |
| else |
| { |
| /* Some bytes were read. Adjust the dest pointer */ |
| |
| dest += bytes_read; |
| |
| /* Were all of the requested bytes read? */ |
| |
| if (bytes_read < count) |
| { |
| /* No. We must be at the end of file. */ |
| |
| goto short_read; |
| } |
| else |
| { |
| /* Yes. We are done. */ |
| |
| count = 0; |
| } |
| } |
| } |
| 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 = read(stream->fs_filedes, stream->fs_bufread, buffer_available); |
| if (bytes_read < 0) |
| { |
| /* An error occurred on the read */ |
| |
| goto err_out; |
| } |
| else if (bytes_read == 0) |
| { |
| /* We are at the end of the file */ |
| |
| goto short_read; |
| } |
| else |
| { |
| /* Some bytes were read */ |
| |
| stream->fs_bufread += bytes_read; |
| } |
| } |
| } |
| } |
| #else |
| /* Now get any other needed chars from the file. */ |
| |
| while (count > 0) |
| { |
| bytes_read = read(stream->fs_filedes, dest, count); |
| if (bytes_read < 0) |
| { |
| goto err_out; |
| } |
| else if (bytes_read == 0) |
| { |
| break; |
| } |
| else |
| { |
| dest += bytes_read; |
| count -= bytes_read; |
| } |
| } |
| #endif |
| short_read: |
| bytes_read = dest - (unsigned char*)ptr; |
| err_out: |
| lib_give_semaphore(stream); |
| } |
| return bytes_read; |
| } |
| |
