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unix: reduce the size of DirEntry

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On platforms where we call `readdir` instead of `readdir_r`, we store
the name as an allocated `CString` for variable length. There's no point
carrying around a full `dirent64` with its fixed-length `d_name` too.
This commit is contained in:
Josh Stone 2022-03-08 13:36:01 -08:00
parent 64187b8374
commit e8b9ba84be
1 changed files with 47 additions and 10 deletions
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51
library/std/src/sys/unix/fs.rs
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@ -228,12 +228,6 @@ struct Dir(*mut libc::DIR);
unsafe impl Send for Dir {}
unsafe impl Sync for Dir {}
pub struct DirEntry {
entry: dirent64,
dir: Arc<InnerReadDir>,
// We need to store an owned copy of the entry name on platforms that use
// readdir() (not readdir_r()), because a) struct dirent may use a flexible
// array to store the name, b) it lives only until the next readdir() call.
#[cfg(any(
target_os = "android",
target_os = "linux",
@ -242,9 +236,46 @@ pub struct DirEntry {
target_os = "fuchsia",
target_os = "redox"
))]
pub struct DirEntry {
dir: Arc<InnerReadDir>,
entry: dirent64_min,
// We need to store an owned copy of the entry name on platforms that use
// readdir() (not readdir_r()), because a) struct dirent may use a flexible
// array to store the name, b) it lives only until the next readdir() call.
name: CString,
}
// Define a minimal subset of fields we need from `dirent64`, especially since
// we're not using the immediate `d_name` on these targets. Keeping this as an
// `entry` field in `DirEntry` helps reduce the `cfg` boilerplate elsewhere.
#[cfg(any(
target_os = "android",
target_os = "linux",
target_os = "solaris",
target_os = "illumos",
target_os = "fuchsia",
target_os = "redox"
))]
struct dirent64_min {
d_ino: u64,
#[cfg(not(any(target_os = "solaris", target_os = "illumos")))]
d_type: u8,
}
#[cfg(not(any(
target_os = "android",
target_os = "linux",
target_os = "solaris",
target_os = "illumos",
target_os = "fuchsia",
target_os = "redox"
)))]
pub struct DirEntry {
dir: Arc<InnerReadDir>,
// The full entry includes a fixed-length `d_name`.
entry: dirent64,
}
#[derive(Clone, Debug)]
pub struct OpenOptions {
// generic
@ -501,8 +532,14 @@ impl Iterator for ReadDir {
let entry_name = entry_bytes.add(name_offset);
ptr::copy_nonoverlapping(entry_bytes, copy_bytes, name_offset);
let entry = dirent64_min {
d_ino: copy.d_ino as u64,
#[cfg(not(any(target_os = "solaris", target_os = "illumos")))]
d_type: copy.d_type as u8,
};
let ret = DirEntry {
entry: copy,
entry,
// d_name is guaranteed to be null-terminated.
name: CStr::from_ptr(entry_name as *const _).to_owned(),
dir: Arc::clone(&self.inner),