Implement posix_getdents

[RajeshRk18]

Closes #2034.

Adds sys_posix_getdents as specified by POSIX.1-2024 posix_getdents, alongside the existing sys_getdents64.

pub unsafe extern "C" fn sys_posix_getdents(fd: RawFd, buf: *mut PosixDent, nbyte: usize, flags: i32) -> isize

PosixDent matches struct posix_dent { d_ino, d_reclen, d_type, d_name[] } . flags must be 0 for now because POSIX defines no mandatory flags and DT_FORCE_TYPE is optional). Anything else returns EINVAL.

Implementation

• The entry-serialization logic that was duplicated across mem.rs and virtio_fs.rs is now a single DirentFormat::write_entry, parameterized over the two entry formats. ObjectInterface::getdents takes the requested DirentFormat.
• The default ObjectInterface::getdents now returns ENOTDIR instead of EINVAL, matching both POSIX and Linux getdents64(2) behavior for non-directory descriptors.

fixes surfaced by the new tests

• DirectoryReader::getdents was unimplemented!(), so sys_opendir + sys_getdents64 panicked the kernel. It is now implemented.
• MemDirectory::traverse_readdir never resolved the final path component.readdir("/tmp/gd") listed the contents of /tmp instead of /tmp/gd. Both went unnoticed because nothing exercised the sys_opendir path before.

Tests

New tests/getdents.rs integration test covers both syscalls through both the sys_opendir and O_DIRECTORY paths: entry layout/reclen for both formats, end-of-directory, partial reads with a one-entry buffer, rejected flags, EINVAL for a too-small buffer, and ENOTDIR for a file descriptor.

[github-actions]

Benchmark Results

Details

Benchmark	Current: 46d9394	Previous: 2e23902	Performance Ratio
startup_benchmark Build Time	94.26 s	80.34 s	1.17 ❗
startup_benchmark File Size	0.79 MB	0.80 MB	0.99 ❗
Startup Time - 1 core	0.74 s (±0.02 s)	0.75 s (±0.02 s)	1.00
Startup Time - 2 cores	0.71 s (±0.02 s)	0.74 s (±0.02 s)	0.97
Startup Time - 4 cores	0.73 s (±0.02 s)	0.74 s (±0.02 s)	0.98
multithreaded_benchmark Build Time	92.46 s	82.11 s	1.13 ❗
multithreaded_benchmark File Size	0.85 MB	0.86 MB	0.99 ❗
Multithreaded Pi Efficiency - 2 Threads	66.32 % (±6.75 %)	85.89 % (±6.61 %)	0.77 ❗
Multithreaded Pi Efficiency - 4 Threads	41.31 % (±2.95 %)	43.43 % (±2.56 %)	0.95
Multithreaded Pi Efficiency - 8 Threads	20.18 % (±1.86 %)	25.76 % (±1.53 %)	0.78 ❗
micro_benchmarks Build Time	208.11 s	80.40 s	2.59 ❗
micro_benchmarks File Size	0.85 MB	0.86 MB	0.99 ❗
Scheduling time - 1 thread	153.00 ticks (±29.90 ticks)	62.65 ticks (±4.06 ticks)	2.44 ❗
Scheduling time - 2 threads	91.39 ticks (±20.12 ticks)	34.08 ticks (±4.10 ticks)	2.68 ❗
Micro - Time for syscall (getpid)	8.88 ticks (±4.23 ticks)	3.45 ticks (±0.58 ticks)	2.57 ❗
Memcpy speed - (built_in) block size 4096	59877.27 MByte/s (±41562.35 MByte/s)	82448.38 MByte/s (±56997.13 MByte/s)	0.73
Memcpy speed - (built_in) block size 1048576	13434.84 MByte/s (±10910.96 MByte/s)	30585.98 MByte/s (±24707.84 MByte/s)	0.44
Memcpy speed - (built_in) block size 16777216	11798.34 MByte/s (±9792.61 MByte/s)	26340.06 MByte/s (±21720.96 MByte/s)	0.45
Memset speed - (built_in) block size 4096	59915.04 MByte/s (±41585.96 MByte/s)	82292.76 MByte/s (±56891.50 MByte/s)	0.73
Memset speed - (built_in) block size 1048576	13611.81 MByte/s (±10993.47 MByte/s)	31323.85 MByte/s (±25145.86 MByte/s)	0.43
Memset speed - (built_in) block size 16777216	12125.40 MByte/s (±9983.55 MByte/s)	27104.68 MByte/s (±22209.94 MByte/s)	0.45
Memcpy speed - (rust) block size 4096	52553.64 MByte/s (±37594.71 MByte/s)	74097.96 MByte/s (±51811.44 MByte/s)	0.71
Memcpy speed - (rust) block size 1048576	12911.05 MByte/s (±10507.39 MByte/s)	30361.60 MByte/s (±24602.37 MByte/s)	0.43
Memcpy speed - (rust) block size 16777216	11376.74 MByte/s (±9427.28 MByte/s)	27625.34 MByte/s (±22806.88 MByte/s)	0.41
Memset speed - (rust) block size 4096	53165.76 MByte/s (±37982.54 MByte/s)	74373.47 MByte/s (±51976.48 MByte/s)	0.71
Memset speed - (rust) block size 1048576	13267.58 MByte/s (±10731.59 MByte/s)	31110.89 MByte/s (±25033.24 MByte/s)	0.43
Memset speed - (rust) block size 16777216	11574.57 MByte/s (±9522.20 MByte/s)	28386.93 MByte/s (±23265.03 MByte/s)	0.41
alloc_benchmarks Build Time	211.79 s	74.76 s	2.83 ❗
alloc_benchmarks File Size	0.87 MB	0.87 MB	0.99 ❗
Allocations - Allocation success	91.38 %	91.31 %	1.00 ❗
Allocations - Deallocation success	100.00 %	100.00 %	1
Allocations - Pre-fail Allocations	61.60 %	61.44 %	1.00 ❗
Allocations - Average Allocation time	23604.24 Ticks (±1625.42 Ticks)	5860.58 Ticks (±98.43 Ticks)	4.03 ❗
Allocations - Average Allocation time (no fail)	24573.12 Ticks (±1902.47 Ticks)	6554.81 Ticks (±92.86 Ticks)	3.75 ❗
Allocations - Average Deallocation time	7488.40 Ticks (±1832.12 Ticks)	1805.01 Ticks (±250.35 Ticks)	4.15 ❗
mutex_benchmark Build Time	218.56 s	79.82 s	2.74 ❗
mutex_benchmark File Size	0.85 MB	0.86 MB	0.99 ❗
Mutex Stress Test Average Time per Iteration - 1 Threads	35.46 ns (±7.52 ns)	12.10 ns (±0.41 ns)	2.93 ❗
Mutex Stress Test Average Time per Iteration - 2 Threads	31.46 ns (±7.42 ns)	40.26 ns (±1.68 ns)	0.78 ❗

This comment was automatically generated by workflow using github-action-benchmark.

[jounathaen]

Overall, looks pretty good to me!

[jounathaen]

Very nice 👍. (Just the CI doc test needs a little fix)

[RajeshRk18]

Very nice 👍. (Just the CI doc test needs a little fix)

thanks! fixing it