98be50a9bc
as specified here: https://pubs.opengroup.org/onlinepubs/007904875/functions/posix_fallocate.html Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
97 lines
3.2 KiB
C
97 lines
3.2 KiB
C
/****************************************************************************
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* libs/libc/unistd/lib_posix_fallocate.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 <fcntl.h>
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#include <errno.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#ifndef CONFIG_DISABLE_MOUNTPOINT
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: posix_fallocate
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*
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* Description:
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* The posix_fallocate() function shall ensure that any required storage for
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* regular file data starting at offset and continuing for len bytes is
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* allocated on the file system storage media. If posix_fallocate() returns
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* successfully, subsequent writes to the specified file data shall not fail
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* due to the lack of free space on the file system storage media.
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*
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* If the offset+len is beyond the current file size, then posix_fallocate()
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* shall adjust the file size to offset+len. Otherwise, the file size shall
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* not be changed.
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*
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* It is implementation-defined whether a previous posix_fadvise() call
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* influences allocation strategy.
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*
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* Space allocated via posix_fallocate() shall be freed by a successful call
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* to creat() or open() that truncates the size of the file. Space allocated
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* via posix_fallocate() may be freed by a successful call to ftruncate()
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* that reduces the file size to a size smaller than offset+ len.
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*
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* Returned Value:
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* Upon successful completion, posix_fallocate() shall return zero;
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* otherwise, an error number shall be returned to indicate the error.
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*
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****************************************************************************/
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int posix_fallocate(int fd, off_t offset, off_t len)
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{
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struct stat st;
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if (offset < 0 || len < 0)
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{
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return EINVAL;
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}
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len += offset;
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if (len < 0)
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{
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return EFBIG;
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}
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if (fstat(fd, &st) != 0)
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{
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return errno;
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}
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if (st.st_size < len)
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{
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if (ftruncate(fd, len) != 0)
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{
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return errno;
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}
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}
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return 0;
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}
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#endif /* !CONFIG_DISABLE_MOUNTPOINT */
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