MattJackson
0d28357b4d
Introduces the SequentialSink / RandomAccessSink trait pair under io::sink and an open_for_mkv dispatch helper that picks WritebackFile on Linux+NFS and LocalFileSink everywhere else. LocalFileSink wraps BufWriter<File> with a 4 MiB buffer and exposes a per-OS preallocate path (fallocate on Linux, F_PREALLOCATE on macOS, no-op fallback). Adds platform::fs_type::detect with a per-OS split (statfs on Linux / macOS, UNC heuristic on Windows, Unknown elsewhere) so construction- site dispatch has a single primitive to call. Blanket impls cover the common shapes: any Write+Send is a SequentialSink, and any SequentialSink+Seek is a RandomAccessSink. WritebackFile satisfies the random-access trait via the blanket impl without needing an explicit per-type impl. No callers wired yet — the mux::resolve construction sites stay on WritebackFile pending Phase 3. Tests: 5 new sink/preallocate tests + 3 fs_type tests (1 ignored, needs a real NFS mount). cargo +1.86 fmt + clippy + tests all green.
49 lines
1.6 KiB
Rust
49 lines
1.6 KiB
Rust
//! macOS `F_PREALLOCATE` extent reservation.
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//!
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//! `fcntl(F_PREALLOCATE)` with `F_ALLOCATECONTIG` first (try for a
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//! contiguous run) and fall back to `F_ALLOCATEALL` (non-contig OK).
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//! Reported file size is unchanged — the muxer's writes still grow it.
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use std::fs::File;
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use std::os::unix::io::AsRawFd;
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// Mirror the Darwin `fstore_t` struct from `<sys/fcntl.h>`. libc on
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// some Rust toolchains/versions doesn't ship this binding, so define
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// it locally with the layout the kernel ABI requires.
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#[repr(C)]
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struct Fstore {
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fst_flags: libc::c_uint,
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fst_posmode: libc::c_int,
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fst_offset: libc::off_t,
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fst_length: libc::off_t,
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fst_bytesalloc: libc::off_t,
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}
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// Constants from <sys/fcntl.h>.
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const F_PREALLOCATE: libc::c_int = 42;
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const F_ALLOCATECONTIG: libc::c_uint = 0x0000_0002;
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const F_ALLOCATEALL: libc::c_uint = 0x0000_0004;
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const F_PEOFPOSMODE: libc::c_int = 3;
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pub(super) fn preallocate_impl(file: &File, size_bytes: u64) {
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let fd = file.as_raw_fd();
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let mut store = Fstore {
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fst_flags: F_ALLOCATECONTIG,
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fst_posmode: F_PEOFPOSMODE,
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fst_offset: 0,
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fst_length: size_bytes as libc::off_t,
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fst_bytesalloc: 0,
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};
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let mut rc = unsafe { libc::fcntl(fd, F_PREALLOCATE, &mut store as *mut Fstore) };
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if rc == -1 {
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// Fall back to non-contiguous.
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store.fst_flags = F_ALLOCATEALL;
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rc = unsafe { libc::fcntl(fd, F_PREALLOCATE, &mut store as *mut Fstore) };
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}
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tracing::debug!(
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target: "mux",
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"LocalFileSink F_PREALLOCATE size_hint={size_bytes} rc={rc} bytesalloc={}",
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store.fst_bytesalloc
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);
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}
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