Implement poll function for axlibc and posix_api

api/arceos_posix_api/Cargo.toml

@@ -26,6 +26,7 @@ net = ["dep:axnet", "axfeat/net", "fd"]
 pipe = ["fd"]
 select = ["fd"]
 epoll = ["fd"]
+poll = ["fd"]
 
 [dependencies]
 # ArceOS modules

api/arceos_posix_api/build.rs

@@ -57,6 +57,8 @@ typedef struct {{
             "pthread_attr_t",
             "pthread_mutex_t",
             "pthread_mutexattr_t",
+            "pollfd",
+            "nfds_t",
             "epoll_event",
             "iovec",
             "clockid_t",

api/arceos_posix_api/ctypes.h

@@ -15,6 +15,7 @@
 #include <sys/epoll.h>
 #include <sys/resource.h>
 #include <sys/select.h>
+#include <sys/poll.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/time.h>

api/arceos_posix_api/src/imp/io_mpx/mod.rs

@@ -18,8 +18,12 @@
 mod epoll;
 #[cfg(feature = "select")]
 mod select;
+#[cfg(feature = "poll")]
+mod poll;
 
 #[cfg(feature = "epoll")]
 pub use self::epoll::{sys_epoll_create, sys_epoll_ctl, sys_epoll_wait};
 #[cfg(feature = "select")]
 pub use self::select::sys_select;
+#[cfg(feature = "poll")]
+pub use self::poll::sys_poll;

api/arceos_posix_api/src/imp/io_mpx/poll.rs

@@ -0,0 +1,68 @@
+use crate::{
+    ctypes,
+    imp::fd_ops::get_file_like,
+};
+use axerrno::{LinuxError, LinuxResult};
+use axhal::time::current_time;
+
+use core::{ffi::c_int, time::Duration};
+
+fn poll_all(fds: &mut [ctypes::pollfd]) -> LinuxResult<usize> {
+    let mut events_num = 0;
+
+    for pollfd_item in fds.iter_mut() {
+        let intfd = pollfd_item.fd;
+        let events = pollfd_item.events;
+        let revents = &mut pollfd_item.revents;
+        match get_file_like(intfd as c_int)?.poll() {
+            Err(_) => {
+                if (events & ctypes::EPOLLERR as i16) != 0 {
+                    *revents |= ctypes::EPOLLERR as i16;
+                }
+            }
+            Ok(state) => {
+                if state.readable && (events & ctypes::EPOLLIN as i16 != 0) {
+                    *revents |= ctypes::EPOLLIN as i16;
+                }
+
+                if state.writable && (events & ctypes::EPOLLOUT as i16 != 0) {
+                    *revents |= ctypes::EPOLLOUT as i16;
+                }                
+            }
+        }
+        events_num += 1;
+    }
+    Ok(events_num)    
+}
+
+// used to monitor multiple file descriptors for events
+pub unsafe fn sys_poll(
+    fds: *mut ctypes::pollfd,
+    nfds: ctypes::nfds_t,
+    timeout: c_int
+) -> c_int{
+    debug!("ax_poll <= nfds: {} timeout: {}", nfds, timeout);
+
+    syscall_body!(ax_poll, {
+        if nfds <= 0 {
+            return Err(LinuxError::EINVAL);
+        }
+        let fds = core::slice::from_raw_parts_mut(fds, nfds as usize);
+        let deadline = (!timeout.is_negative())
+            .then(|| current_time() + Duration::from_millis(timeout as u64));
+        loop {
+            #[cfg(feature = "net")]
+            axnet::poll_interfaces();
+            let fds_num = poll_all(fds)?;
+            if fds_num > 0 {
+                return Ok(fds_num as c_int);
+            }
+
+            if deadline.map_or(false, |ddl| current_time() >= ddl) {
+                debug!("    timeout!");
+                return Ok(0);
+            }
+            crate::sys_sched_yield();
+        }
+    })
+}

api/arceos_posix_api/src/imp/mod.rs

@@ -19,7 +19,7 @@ pub mod time;
 pub mod fd_ops;
 #[cfg(feature = "fs")]
 pub mod fs;
-#[cfg(any(feature = "select", feature = "epoll"))]
+#[cfg(any(feature = "select", feature = "poll", feature = "epoll"))]
 pub mod io_mpx;
 #[cfg(feature = "net")]
 pub mod net;

api/arceos_posix_api/src/lib.rs

@@ -55,6 +55,8 @@ pub use imp::fs::{sys_fstat, sys_getcwd, sys_lseek, sys_lstat, sys_open, sys_ren
 pub use imp::io_mpx::sys_select;
 #[cfg(feature = "epoll")]
 pub use imp::io_mpx::{sys_epoll_create, sys_epoll_ctl, sys_epoll_wait};
+#[cfg(feature = "poll")]
+pub use imp::io_mpx::sys_poll;
 #[cfg(feature = "net")]
 pub use imp::net::{
     sys_accept, sys_bind, sys_connect, sys_freeaddrinfo, sys_getaddrinfo, sys_getpeername,

scripts/make/features.mk

@@ -14,7 +14,7 @@
 ifeq ($(APP_TYPE),c)
   ax_feat_prefix := axfeat/
   lib_feat_prefix := axlibc/
-  lib_features := fp_simd alloc multitask fs net fd pipe select epoll
+  lib_features := fp_simd alloc multitask fs net fd pipe select poll epoll
 else
   # TODO: it's better to use `axfeat/` as `ax_feat_prefix`, but all apps need to have `axfeat` as a dependency
   ax_feat_prefix := axstd/
@@ -28,7 +28,7 @@ ifeq ($(APP_TYPE), c)
   ifneq ($(wildcard $(APP)/features.txt),)    # check features.txt exists
     override FEATURES += $(shell cat $(APP)/features.txt)
   endif
-  ifneq ($(filter fs net pipe select epoll,$(FEATURES)),)
+  ifneq ($(filter fs net pipe select poll epoll,$(FEATURES)),)
     override FEATURES += fd
   endif
 endif

ulib/axlibc/Cargo.toml

@@ -45,6 +45,7 @@ net = ["arceos_posix_api/net", "fd"]
 fd = []
 pipe = ["arceos_posix_api/pipe"]
 select = ["arceos_posix_api/select"]
+poll = ["arceos_posix_api/poll"]
 epoll = ["arceos_posix_api/epoll"]
 
 [dependencies]

ulib/axlibc/src/io_mpx.rs

@@ -13,6 +13,8 @@ use core::ffi::c_int;
 
 #[cfg(feature = "select")]
 use arceos_posix_api::sys_select;
+#[cfg(feature = "poll")]
+use arceos_posix_api::sys_poll;
 #[cfg(feature = "epoll")]
 use arceos_posix_api::{sys_epoll_create, sys_epoll_ctl, sys_epoll_wait};
 
@@ -61,3 +63,15 @@ pub unsafe extern "C" fn select(
 ) -> c_int {
     e(sys_select(nfds, readfds, writefds, exceptfds, timeout))
 }
+
+
+/// Monitor multiple file descriptors, waiting until one or more of the file descriptors become "ready" for some class of I/O operation
+#[cfg(feature = "poll")]
+#[no_mangle]
+pub unsafe extern "C" fn poll(
+    fds: *mut ctypes::pollfd,
+    nfds: ctypes::nfds_t,
+    timeout: c_int
+) -> c_int {
+    e(sys_poll(fds, nfds, timeout))
+}

ulib/axlibc/src/lib.rs

@@ -62,7 +62,7 @@ mod utils;
 mod fd_ops;
 #[cfg(feature = "fs")]
 mod fs;
-#[cfg(any(feature = "select", feature = "epoll"))]
+#[cfg(any(feature = "select", feature = "poll", feature = "epoll"))]
 mod io_mpx;
 #[cfg(feature = "alloc")]
 mod malloc;
@@ -127,6 +127,8 @@ pub use self::pipe::pipe;
 
 #[cfg(feature = "select")]
 pub use self::io_mpx::select;
+#[cfg(feature = "poll")]
+pub use self::io_mpx::poll;
 #[cfg(feature = "epoll")]
 pub use self::io_mpx::{epoll_create, epoll_ctl, epoll_wait};