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NAMEposix_fallocate - pre-allocate storage for a range in a file
SYNOPSISIn fcntl.h Ft int Fn posix_fallocate int fd off_t offset off_t len
DESCRIPTIONRequired storage for the range Fa offset to Fa offset + Fa len in the file referenced by Fa fd is guaranteed to be allocated upon successful return. That is, if Fn posix_fallocate returns successfully, subsequent writes to the specified file data will not fail due to lack of free space on the file system storage media. Any existing file data in the specified range is unmodified. If Fa offset + Fa len is beyond the current file size, then Fn posix_fallocate will adjust the file size to Fa offset + Fa len . Otherwise, the file size will not be changed.
Space allocated by Fn posix_fallocate will be freed by a successful call to creat(2) or open(2) that truncates the size of the file. Space allocated via Fn posix_fallocate may be freed by a successful call to ftruncate(2) that reduces the file size to a size smaller than Fa offset + Fa len .
RETURN VALUESIf successful, Fn posix_fallocate returns zero. It returns an error on failure, without setting errno
ERRORSPossible failure conditions:
- Bq Er EBADF
- The Fa fd argument is not a valid file descriptor.
- Bq Er EBADF
- The Fa fd argument references a file that was opened without write permission.
- Bq Er EFBIG
- The value of Fa offset + Fa len is greater than the maximum file size.
- Bq Er EINTR
- A signal was caught during execution.
- Bq Er EINVAL
- The Fa len argument was less than or equal to zero or the Fa offset argument was less than zero.
- Bq Er EIO
- An I/O error occurred while reading from or writing to a file system.
- Bq Er ENODEV
- The Fa fd argument does not refer to a regular file.
- Bq Er ENOSPC
- There is insufficient free space remaining on the file system storage media.
- Bq Er ESPIPE
- The Fa fd argument is associated with a pipe or FIFO.