From e6599e17a899f37b2e9732a9d8073d74c11441d6 Mon Sep 17 00:00:00 2001
From: Yuriy Ponomarev <y@ponomarev.su>
Date: Wed, 26 Sep 2018 11:01:56 +0300
Subject: [PATCH 1/5] Custom baudrates on linux

---
 serial_linux.go | 35 +++++++++++++++++++++++++++++++++++
 serial_posix.go | 14 ++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/serial_linux.go b/serial_linux.go
index 35606b2..45bae5b 100644
--- a/serial_linux.go
+++ b/serial_linux.go
@@ -101,3 +101,38 @@ func fdisset(fd int, fds *syscall.FdSet) bool {
 	idx, pos := fdget(fd, fds)
 	return fds.Bits[idx]&(1<<uint(pos)) != 0
 }
+
+const (
+	// baudrate ioctls
+	TCGETS2 = 0x802C542A
+	TCSETS2 = 0x402C542B
+	CBAUD   = 0x100F
+	BOTHER  = 0x1000 //0o010000
+)
+
+func isCustomBaudrate(baudrate int) bool {
+	var ok bool
+	_, ok = baudRates[baudrate]
+	return !ok
+}
+
+func setSpecialBaudrate(fd int, baudrate int) (bool, syscall.Errno) {
+	var buf [64]int32 // right size is 44 on x86_64, allow for some growth
+
+	_, _, errno := syscall.Syscall(uintptr(syscall.SYS_IOCTL),
+		uintptr(fd), uintptr(TCGETS2), uintptr(unsafe.Pointer(&buf)))
+	if errno != 0 {
+		return false, errno
+	}
+	// set custom speed
+	buf[2] &^= CBAUD
+	buf[2] |= BOTHER
+	buf[9], buf[10] = int32(baudrate), int32(baudrate)
+	_, _, errno = syscall.Syscall(uintptr(syscall.SYS_IOCTL),
+		uintptr(fd), uintptr(TCSETS2), uintptr(unsafe.Pointer(&buf)))
+	if errno != 0 {
+		return false, errno
+	}
+
+	return true, syscall.Errno(0)
+}
diff --git a/serial_posix.go b/serial_posix.go
index 6d25b2d..e775d30 100644
--- a/serial_posix.go
+++ b/serial_posix.go
@@ -43,6 +43,11 @@ func New() Port {
 
 // Open connects to the given serial port.
 func (p *port) Open(c *Config) (err error) {
+	var custom_baudrate int
+	if isCustomBaudrate(c.BaudRate) {
+		custom_baudrate = c.BaudRate
+		c.BaudRate = 38400
+	}
 	termios, err := newTermios(c)
 	if err != nil {
 		return
@@ -68,6 +73,15 @@ func (p *port) Open(c *Config) (err error) {
 		return err
 	}
 	p.timeout = c.Timeout
+
+	if custom_baudrate > 0 {
+		c.BaudRate = custom_baudrate
+		ok, errno := setSpecialBaudrate(p.fd, custom_baudrate)
+		if !ok {
+			return error(errno)
+		}
+	}
+
 	return
 }
 

From 4def6ef9a94833f8f1b84602b496cd2745336ac1 Mon Sep 17 00:00:00 2001
From: Edgar <44380483+Edgar242@users.noreply.github.com>
Date: Fri, 14 Jun 2019 17:27:56 -0500
Subject: [PATCH 2/5] When the port Address number was grater than 10 the port
 couldn't be oppened, and a solution to this problem is adding those back
 slashes, other libraries are using this method.

---
 serial_windows.go | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/serial_windows.go b/serial_windows.go
index 1eeb14b..1ff72af 100644
--- a/serial_windows.go
+++ b/serial_windows.go
@@ -156,13 +156,17 @@ func (p *port) setSerialConfig(c *Config) error {
 }
 
 func newHandle(c *Config) (handle syscall.Handle, err error) {
+	name := c.Address
+	if len(name) > 0 && name[0] != '\\' {
+		name = "\\\\.\\" + name
+	}
 	handle, err = syscall.CreateFile(
-		syscall.StringToUTF16Ptr(c.Address),
+		syscall.StringToUTF16Ptr(name),
 		syscall.GENERIC_READ|syscall.GENERIC_WRITE,
-		0,   // mode
-		nil, // security
+		0,                     // mode
+		nil,                   // security
 		syscall.OPEN_EXISTING, // create mode
-		0, // attributes
-		0) // templates
+		0,                     // attributes
+		0)                     // templates
 	return
 }

From 51016b570a6ce27593c36d23dd095ec3685ebc51 Mon Sep 17 00:00:00 2001
From: Iurii Ponomarev <y@ponomarev.su>
Date: Wed, 25 Dec 2019 15:47:24 +0300
Subject: [PATCH 3/5] go module created

---
 go.mod | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 go.mod

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..02c969c
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/y-ponomarev/serial
+
+go 1.13

From 5a71da530865cb315af89cac2f56df09779ff96f Mon Sep 17 00:00:00 2001
From: Aleksey Bakin <alexey.bakin@gmail.com>
Date: Mon, 27 Dec 2021 10:15:37 +0300
Subject: [PATCH 4/5] fix: use syscall poll instead of select to avoid
 limitations

---
 serial_posix.go | 44 ++++++++++++++++++++++----------------------
 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/serial_posix.go b/serial_posix.go
index 6d25b2d..64939f0 100644
--- a/serial_posix.go
+++ b/serial_posix.go
@@ -85,33 +85,33 @@ func (p *port) Close() (err error) {
 // Read reads from serial port. Port must be opened before calling this method.
 // It is blocked until all data received or timeout after p.timeout.
 func (p *port) Read(b []byte) (n int, err error) {
-	var rfds syscall.FdSet
+	fds := []unix.PollFd{{Fd: int32(p.fd), Events: unix.POLLIN}}
+	deadline := time.Now().Add(p.timeout)
 
-	fd := p.fd
-	fdset(fd, &rfds)
-
-	var tv *syscall.Timeval
-	if p.timeout > 0 {
-		timeout := syscall.NsecToTimeval(p.timeout.Nanoseconds())
-		tv = &timeout
-	}
 	for {
-		// If syscall.Select() returns EINTR (Interrupted system call), retry it
-		if err = syscallSelect(fd+1, &rfds, nil, nil, tv); err == nil {
-			break
+		timeout := -1
+		if p.timeout > 0 {
+			timeout = int(deadline.Sub(time.Now()).Milliseconds())
 		}
-		if err != syscall.EINTR {
-			err = fmt.Errorf("serial: could not select: %v", err)
-			return
+
+		n, err := unix.Poll(fds, timeout)
+		if err != nil {
+			if errors.Is(err, syscall.EINTR) {
+				continue
+			}
+			return 0, fmt.Errorf("serial: could not poll: %v", err)
+		}
+
+		if n == 0 {
+			return 0, ErrTimeout
+		}
+
+		if fds[0].Revents&unix.POLLIN == unix.POLLIN {
+			break
 		}
 	}
-	if !fdisset(fd, &rfds) {
-		// Timeout
-		err = ErrTimeout
-		return
-	}
-	n, err = syscall.Read(fd, b)
-	return
+
+	return syscall.Read(p.fd, b)
 }
 
 // Write writes data to the serial port.

From 9393de881e7e63ad5d66e7cba85231300db922b5 Mon Sep 17 00:00:00 2001
From: Iurii Ponomarev <y@ponomarev.su>
Date: Mon, 31 Jan 2022 17:27:38 +0300
Subject: [PATCH 5/5] fix build after merge PR #3

---
 go.mod          | 2 ++
 go.sum          | 2 ++
 serial_posix.go | 1 +
 3 files changed, 5 insertions(+)
 create mode 100644 go.sum

diff --git a/go.mod b/go.mod
index 02c969c..c556438 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module github.com/y-ponomarev/serial
 
 go 1.13
+
+require golang.org/x/sys v0.0.0-20220128215802-99c3d69c2c27 // indirect
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..15089f2
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+golang.org/x/sys v0.0.0-20220128215802-99c3d69c2c27 h1:XDXtA5hveEEV8JB2l7nhMTp3t3cHp9ZpwcdjqyEWLlo=
+golang.org/x/sys v0.0.0-20220128215802-99c3d69c2c27/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
diff --git a/serial_posix.go b/serial_posix.go
index 79bc7c2..009e878 100644
--- a/serial_posix.go
+++ b/serial_posix.go
@@ -10,6 +10,7 @@ import (
 	"syscall"
 	"time"
 	"unsafe"
+    "golang.org/x/sys/unix"
 )
 
 // port implements Port interface.