diff options
Diffstat (limited to 'nuttx/lib/lib_libfread.c')
| -rw-r--r-- | nuttx/lib/lib_libfread.c | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/nuttx/lib/lib_libfread.c b/nuttx/lib/lib_libfread.c new file mode 100644 index 0000000000..8c3deb6559 --- /dev/null +++ b/nuttx/lib/lib_libfread.c @@ -0,0 +1,257 @@ +/************************************************************ + * lib_libfread.c + * + * Copyright (C) 2007 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 Gregory Nutt 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 <string.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 + /* 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; +} |