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|
package fallocate
import (
"syscall"
"unsafe"
"golang.org/x/sys/unix"
)
func fallocate(fd int, mode uint32, off int64, len int64) error {
// TODO: Handle `mode` parameter.
_ = mode
// From `man fcntl` on OSX:
// The F_PREALLOCATE command operates on the following structure:
//
// typedef struct fstore {
// u_int32_t fst_flags; /* IN: flags word */
// int fst_posmode; /* IN: indicates offset field */
// off_t fst_offset; /* IN: start of the region */
// off_t fst_length; /* IN: size of the region */
// off_t fst_bytesalloc; /* OUT: number of bytes allocated */
// } fstore_t;
//
// The flags (fst_flags) for the F_PREALLOCATE command are as follows:
//
// F_ALLOCATECONTIG Allocate contiguous space.
//
// F_ALLOCATEALL Allocate all requested space or no space at all.
//
// The position modes (fst_posmode) for the F_PREALLOCATE command indicate how to use the offset field. The modes are as fol-
// lows:
//
// F_PEOFPOSMODE Allocate from the physical end of file.
//
// F_VOLPOSMODE Allocate from the volume offset.
k := struct {
Flags uint32 // u_int32_t
Posmode int64 // int
Offset int64 // off_t
Length int64 // off_t
Bytesalloc int64 // off_t
}{
0,
0,
int64(off),
int64(len),
0,
}
_, _, errno := unix.Syscall(syscall.SYS_FCNTL, uintptr(fd), uintptr(unix.F_PREALLOCATE), uintptr(unsafe.Pointer(&k)))
if errno != 0 {
return errno
}
return nil
}
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