84 lines
2.6 KiB
C
84 lines
2.6 KiB
C
/****************************************************************************
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* libs/libc/unistd/lib_getentropy.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <sys/random.h>
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#include <errno.h>
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#include <unistd.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: getentropy
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*
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* Description:
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* The getentropy() function writes length bytes of high-quality
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* random data to the buffer starting at the location pointed to by
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* buffer. The maximum permitted value for the length argument is
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* 256.
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*
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* A successful call to getentropy() always provides the requested
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* number of bytes of entropy.
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*
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* Input Parameters:
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* buffer - Buffer for returned random bytes
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* length - Number of bytes requested.
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*
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* Returned Value:
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* On success, this function returns zero. On error, -1 is
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* returned, and errno is set to indicate the error.
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*
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****************************************************************************/
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int getentropy(FAR void *buffer, size_t length)
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{
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FAR char *pos = buffer;
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if (length > 256)
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{
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set_errno(EIO);
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return -1;
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}
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while (length > 0)
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{
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int ret = getrandom(pos, length, 0);
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if (ret < 0)
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{
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if (get_errno() == EINTR)
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{
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continue;
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}
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return ret;
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}
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pos += ret;
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length -= ret;
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}
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return 0;
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}
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