nanosleep doesn't work as expected

[daichifukui]

Description

nanosleep does not respect the sleep duration and the routine returns immediately if the duration is shorter than 1 second.

Conditions

• wasix-libc HEAD: 0374d06
• Compiler: clang version 16.0.0, Target: wasm32-unknown-wasi, Thread model: posix, InstalledDir: /home/user/wasi-sdk-20.0/bin
• Runtime: wasmer 4.1.1

Steps to reproduce

1. view source code

$ cat nanosleep_main.c
#include <time.h>
#include <stdio.h>

int main(void)
{
        int ret;
        struct timespec ts;
        ts.tv_nsec=999999999;
        ret = nanosleep(&ts, NULL);
        if (ret)
                perror("clock_nanosleep");
        return 0;
}

2. compile

$ /home/user/wasi-sdk-20.0/bin/clang \
--sysroot=/home/user/wasix-libc/sysroot \
-Wall \
-Wno-nonnull \
-Wextra \
-O2 \
-Wl,--max-memory=4294967296 \
-Wl,--export-dynamic \
nanosleep_main.c \
-o n_main

3. run

$ /home/user/.wasmer/bin/wasmer run --enable-all --verbose ./n_main
2023-09-22T05:15:10.482290Z  INFO ThreadId(01) execute_wasm: wasmer_cli::commands::run: enter
2023-09-22T05:15:10.482572Z  INFO ThreadId(01) execute_wasm:execute_wasi_module: wasmer_cli::commands::run: enter
2023-09-22T05:15:10.483636Z  INFO ThreadId(01) execute_wasm:execute_wasi_module: wasmer_cli::commands::run: close time.busy=1.06ms time.idle=1.52µs
2023-09-22T05:15:10.483794Z  INFO ThreadId(01) execute_wasm: wasmer_cli::commands::run: close time.busy=1.51ms time.idle=2.76µs

With regard to the result above, nanosleep should sleep for 999999999ns (almost 1 second) but it sleeps for around 1.5ms, which is much shorter than expected

Expected behaviour

nanosleep sleeps for requested duration even if the duration is shorter than 1 second

Actual behaviour

nanosleep sleeps for only a few milliseconds and returns immediately if the duration is shorter than 1 second

Additional info

nanosleep works as expected if the duration is equal to or longer than 1 second.

# view source code
$ cat nanosleep_main_1s.c
#include <time.h>
#include <stdio.h>

int main(void)
{
        int ret;
        struct timespec ts;
        ts.tv_sec=1;
        ret = nanosleep(&ts, NULL);
        if (ret)
                perror("clock_nanosleep");
        return 0;
}

# compile
$ /home/user/wasi-sdk-20.0/bin/clang \
--sysroot=/home/user/wasix-libc/sysroot \
-Wall \
-Wno-nonnull \
-Wextra \
-O2 \
-Wl,--max-memory=4294967296 \
-Wl,--export-dynamic \
nanosleep_main_1s.c \
-o n_main_1s

# run
$ /home/user/.wasmer/bin/wasmer run --enable-all --verbose ./n_main_1s
2023-09-22T04:43:46.802396Z  INFO ThreadId(01) execute_wasm: wasmer_cli::commands::run: enter
2023-09-22T04:43:46.802479Z  INFO ThreadId(01) execute_wasm:execute_wasi_module: wasmer_cli::commands::run: enter
2023-09-22T04:43:47.811808Z  INFO ThreadId(01) execute_wasm:execute_wasi_module: wasmer_cli::commands::run: close time.busy=1.01s time.idle=2.82µs
2023-09-22T04:43:47.811890Z  INFO ThreadId(01) execute_wasm: wasmer_cli::commands::run: close time.busy=1.01s time.idle=3.73µs

In addition, if we use wasi-libc instead of wasix-libc, nanosleep works as expected with the sleep duration shorter than 1 second

$ cat nanosleep_main.c
#include <time.h>
#include <stdio.h>

int main(void)
{
        int ret;
        struct timespec ts;
        ts.tv_nsec=999999999;
        ret = nanosleep(&ts, NULL);
        if (ret)
                perror("clock_nanosleep");
        return 0;
}

$ /home/user/wasi-sdk-20.0/bin/clang \
--sysroot=/home/user/wasi-libc/sysroot/ \
-Wall \
-Wno-nonnull \
-Wextra \
-O2 \
-Wl,--max-memory=4294967296 \
-Wl,--export-dynamic \
nanosleep_main.c \
-o n_main

$ /home/user/.wasmer/bin/wasmer run --enable-all --verbose ./n_main
2023-09-22T06:07:26.452257Z  INFO ThreadId(01) execute_wasm: wasmer_cli::commands::run: enter
2023-09-22T06:07:26.452517Z  INFO ThreadId(01) execute_wasm:execute_wasi_module: wasmer_cli::commands::run: enter
2023-09-22T06:07:27.454365Z  INFO ThreadId(01) execute_wasm:execute_wasi_module: wasmer_cli::commands::run: close time.busy=1.00s time.idle=2.81µs
2023-09-22T06:07:27.454435Z  INFO ThreadId(01) execute_wasm: wasmer_cli::commands::run: close time.busy=1.00s time.idle=3.11µs