|POSIX_FALLOCATE(3P)||POSIX Programmer's Manual||POSIX_FALLOCATE(3P)|
int posix_fallocate(int fd, off_t offset, off_t len);
If the offset+len is beyond the current file size, then posix_fallocate() shall adjust the file size to offset+len. Otherwise, the file size shall not be changed.
It is implementation-defined whether a previous posix_fadvise() call influences allocation strategy.
Space allocated via posix_fallocate() shall be freed by a successful call to creat() or open() that truncates the size of the file. Space allocated via posix_fallocate() may be freed by a successful call to ftruncate() that reduces the file size to a size smaller than offset+len.
- The fd argument is not a valid file descriptor.
- The fd argument references a file that was opened without write permission.
- The value of offset+len is greater than the maximum file size.
- A signal was caught during execution.
- The len argument is less than zero, or the offset argument is less than zero, or the underlying file system does not support this operation.
- An I/O error occurred while reading from or writing to a file system.
- The fd argument does not refer to a regular file.
- There is insufficient free space remaining on the file system storage media.
- The fd argument is associated with a pipe or FIFO.
The posix_fallocate() function may fail if:
- The len argument is zero.
The following sections are informative.
The Base Definitions volume of POSIX.1‐2017, <fcntl.h>
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|2017||IEEE/The Open Group|