rt-thread-official/components/libc/compilers/dlib/syscall_read.c

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/*
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* Copyright (c) 2006-2021, RT-Thread Development Team
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*
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* SPDX-License-Identifier: Apache-2.0
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*
* Change Logs:
* Date Author Notes
* 2015-01-28 Bernard first version
*/
#include <rtthread.h>
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#include <LowLevelIOInterface.h>
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#include <unistd.h>
#ifdef RT_USING_POSIX_DEVIO
#include "libc.h"
#endif /* RT_USING_POSIX_DEVIO */
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#include <compiler_private.h>
#define DBG_TAG "dlib.syscall.read"
#define DBG_LVL DBG_INFO
#include <rtdbg.h>
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/*
* The "__read" function reads a number of bytes, at most "size" into
* the memory area pointed to by "buffer". It returns the number of
* bytes read, 0 at the end of the file, or _LLIO_ERROR if failure
* occurs.
*
* The template implementation below assumes that the application
* provides the function "MyLowLevelGetchar". It should return a
* character value, or -1 on failure.
*/
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#pragma module_name = "?__read"
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size_t __read(int handle, unsigned char *buf, size_t len)
{
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#ifdef DFS_USING_POSIX
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int size;
if (handle == _LLIO_STDIN)
{
#ifdef RT_USING_POSIX_DEVIO
if (libc_stdio_get_console() < 0)
{
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LOG_W("Do not invoke standard input before initializing compiler-libc");
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return 0; /* error, but keep going */
}
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return read(STDIN_FILENO, buf, len); /* return the length of the data read */
#else
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LOG_W(warning_without_devio);
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return _LLIO_ERROR;
#endif /* RT_USING_POSIX_DEVIO */
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}
else if ((handle == _LLIO_STDOUT) || (handle == _LLIO_STDERR))
{
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return _LLIO_ERROR;
}
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size = read(handle, buf, len);
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return size; /* return the length of the data read */
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#else
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LOG_W(warning_without_fs);
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return _LLIO_ERROR;
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#endif /* DFS_USING_POSIX */
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}