From a44ff7813affb946c0a45a7d0b4b1755d352da89 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Fri, 24 Jan 2025 11:34:03 +0200
Subject: [PATCH] picoev: enable running veb services on Termux

---
 vlib/picoev/loop_termux.c.v | 143 ++++++++++++++++++++++++++++++++++++
 vlib/picoev/picoev.v        |   2 +-
 vlib/picoev/socket_util.c.v |   2 +-
 3 files changed, 145 insertions(+), 2 deletions(-)
 create mode 100644 vlib/picoev/loop_termux.c.v

diff --git a/vlib/picoev/loop_termux.c.v b/vlib/picoev/loop_termux.c.v
new file mode 100644
index 00000000000000..8a9465df9b95a8
--- /dev/null
+++ b/vlib/picoev/loop_termux.c.v
@@ -0,0 +1,143 @@
+module picoev
+
+#include <sys/epoll.h>
+
+$if !musl ? {
+	#include <sys/cdefs.h> // needed for cross compiling to linux
+}
+
+fn C.epoll_create(__flags int) int
+fn C.epoll_wait(__epfd int, __events &C.epoll_event, __maxevents int, __timeout int) int
+fn C.epoll_ctl(__epfd int, __op int, __fd int, __event &C.epoll_event) int
+
+@[typedef]
+union C.epoll_data {
+mut:
+	ptr voidptr
+	fd  int
+	u32 u32
+	u64 u64
+}
+
+@[packed]
+pub struct C.epoll_event {
+	events u32
+	data   C.epoll_data
+}
+
+@[heap]
+pub struct EpollLoop {
+mut:
+	id       int
+	epoll_fd int
+	events   [1024]C.epoll_event
+	now      i64
+}
+
+type LoopType = EpollLoop
+
+// create_epoll_loop creates a new epoll instance for and returns an
+// `EpollLoop` struct with `id`
+pub fn create_epoll_loop(id int) !&EpollLoop {
+	mut loop := &EpollLoop{
+		id: id
+	}
+
+	loop.epoll_fd = C.epoll_create(max_fds)
+	if loop.epoll_fd == -1 {
+		return error('could not create epoll loop!')
+	}
+
+	return loop
+}
+
+@[direct_array_access]
+fn (mut pv Picoev) update_events(fd int, events int) int {
+	// check if fd is in range
+	assert fd < max_fds
+
+	mut target := pv.file_descriptors[fd]
+	mut ev := C.epoll_event{}
+
+	// fd belongs to loop
+	if events & picoev_del != target.events && target.loop_id != pv.loop.id {
+		return -1
+	}
+
+	if events & picoev_readwrite == target.events {
+		return 0
+	}
+
+	// vfmt off
+	ev.events = u32(
+		(if events & picoev_read != 0 { C.EPOLLIN } else { 0 })
+			|
+		(if events & picoev_write != 0 { C.EPOLLOUT } else { 0 })
+	)
+	// vfmt on
+	ev.data.fd = fd
+
+	if events & picoev_del != 0 {
+		// nothing to do
+	} else if events & picoev_readwrite == 0 {
+		// delete the file if it exists
+		epoll_ret := C.epoll_ctl(pv.loop.epoll_fd, C.EPOLL_CTL_DEL, fd, &ev)
+
+		// check error
+		assert epoll_ret == 0
+	} else {
+		// change settings to 0
+		mut epoll_ret := C.epoll_ctl(pv.loop.epoll_fd, C.EPOLL_CTL_MOD, fd, &ev)
+		if epoll_ret != 0 {
+			// if the file is not present we want to add it
+			assert C.errno == C.ENOENT
+			epoll_ret = C.epoll_ctl(pv.loop.epoll_fd, C.EPOLL_CTL_ADD, fd, &ev)
+
+			// check error
+			assert epoll_ret == 0
+		}
+	}
+
+	// convert to u32?
+	target.events = u32(events)
+	return 0
+}
+
+@[direct_array_access]
+fn (mut pv Picoev) poll_once(max_wait_in_sec int) int {
+	nevents := C.epoll_wait(pv.loop.epoll_fd, &pv.loop.events[0], max_fds, max_wait_in_sec * 1000)
+
+	if nevents == -1 {
+		// timeout has occurred
+		return -1
+	}
+
+	for i := 0; i < nevents; i++ {
+		mut event := pv.loop.events[i]
+		target := unsafe { pv.file_descriptors[event.data.fd] }
+		unsafe {
+			assert event.data.fd < max_fds
+		}
+		if pv.loop.id == target.loop_id && target.events & picoev_readwrite != 0 {
+			mut read_events := 0
+			if event.events & u32(C.EPOLLIN) != 0 {
+				read_events |= picoev_read
+			}
+			if event.events & u32(C.EPOLLOUT) != 0 {
+				read_events |= picoev_write
+			}
+
+			if read_events != 0 {
+				// do callback!
+				unsafe { target.cb(event.data.fd, read_events, &pv) }
+			}
+		} else {
+			// defer epoll delete
+			event.events = 0
+			unsafe {
+				C.epoll_ctl(pv.loop.epoll_fd, C.EPOLL_CTL_DEL, event.data.fd, &event)
+			}
+		}
+	}
+	return 0
+}
diff --git a/vlib/picoev/picoev.v b/vlib/picoev/picoev.v
index e75893a27faa3e..587a752fd3dd89 100644
--- a/vlib/picoev/picoev.v
+++ b/vlib/picoev/picoev.v
@@ -323,7 +323,7 @@ pub fn new(config Config) !&Picoev {
 	// epoll on linux
 	// kqueue on macos and bsd
 	// select on windows and others
-	$if linux {
+	$if linux || termux {
 		pv.loop = create_epoll_loop(0) or { panic(err) }
 	} $else $if freebsd || macos {
 		pv.loop = create_kqueue_loop(0) or { panic(err) }
diff --git a/vlib/picoev/socket_util.c.v b/vlib/picoev/socket_util.c.v
index 7357536f4e148f..fad62987b1bf77 100644
--- a/vlib/picoev/socket_util.c.v
+++ b/vlib/picoev/socket_util.c.v
@@ -104,7 +104,7 @@ fn listen(config Config) !int {
 		// can be accepted
 		net.socket_error(C.setsockopt(fd, C.IPPROTO_IPV6, C.IPV6_V6ONLY, &flag_zero, sizeof(int)))!
 	}
-	$if linux {
+	$if linux || termux {
 		// epoll socket options
 		net.socket_error(C.setsockopt(fd, C.SOL_SOCKET, C.SO_REUSEPORT, &flag, sizeof(int)))!
 		net.socket_error(C.setsockopt(fd, C.IPPROTO_TCP, C.TCP_QUICKACK, &flag, sizeof(int)))!