pppd: Fix usage of BOTHER ioctl API on Linux (#314)

[ppp.git] / pppd / termios_linux.h

diff --git a/pppd/termios_linux.h b/pppd/termios_linux.h
new file mode 100644 (file)
index 0000000..9c79d16
--- /dev/null
+++ b/pppd/termios_linux.h
@@ -0,0 +1,194 @@
+/* SPDX-License-Identifier: GPL-2.0+ OR BSD-4-Clause OR BSD-3-Clause OR BSD-2-Clause */
+/*
+ * termios fuctions to support arbitrary baudrates (on Linux)
+ *
+ * Copyright (c) 2021 Pali Rohár <pali@kernel.org>
+ * Copyright (c) 2021 Marek Behún <kabel@kernel.org>
+ */
+
+#ifndef _TERMIOS_LINUX_H_
+#define _TERMIOS_LINUX_H_
+
+/*
+ * We need to use raw TCGETS2/TCSETS2 or TCGETS/TCSETS ioctls with the BOTHER
+ * flag in struct termios2/termios, defined in Linux headers <asm/ioctls.h>
+ * and <asm/termbits.h>. Since these headers conflict with glibc's header file
+ * <termios.h>, it is not possible to use libc's termios functions and we need
+ * to reimplement them via ioctl() calls.
+ *
+ * An arbitrary baudrate is supported when the macro BOTHER is defined. The
+ * baudrate value itself is then stored into the c_ospeed and c_ispeed members.
+ * If ioctls TCGETS2/TCSETS2 are defined and supported then these fields are
+ * present in struct termios2, otherwise these fields are present in struct
+ * termios.
+ *
+ * Note that the Bnnn constants from <termios.h> need not be compatible with
+ * Bnnn constants from <asm/termbits.h>.
+ */
+
+#include <errno.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <asm/ioctls.h>
+#include <asm/termbits.h>
+
+#if defined(BOTHER) && defined(TCGETS2)
+#define termios termios2
+#endif
+
+static inline int tcgetattr(int fd, struct termios *t)
+{
+#if defined(BOTHER) && defined(TCGETS2)
+       return ioctl(fd, TCGETS2, t);
+#else
+       return ioctl(fd, TCGETS, t);
+#endif
+}
+
+static inline int tcsetattr(int fd, int a, const struct termios *t)
+{
+       int cmd;
+
+       switch (a) {
+#if defined(BOTHER) && defined(TCGETS2)
+       case TCSANOW:
+               cmd = TCSETS2;
+               break;
+       case TCSADRAIN:
+               cmd = TCSETSW2;
+               break;
+       case TCSAFLUSH:
+               cmd = TCSETSF2;
+               break;
+#else
+       case TCSANOW:
+               cmd = TCSETS;
+               break;
+       case TCSADRAIN:
+               cmd = TCSETSW;
+               break;
+       case TCSAFLUSH:
+               cmd = TCSETSF;
+               break;
+#endif
+       default:
+               errno = EINVAL;
+               return -1;
+       }
+
+       return ioctl(fd, cmd, t);
+}
+
+static inline int tcdrain(int fd)
+{
+       return ioctl(fd, TCSBRK, 1);
+}
+
+static inline int tcflush(int fd, int q)
+{
+       return ioctl(fd, TCFLSH, q);
+}
+
+static inline int tcsendbreak(int fd, int d)
+{
+#ifdef TCSBRKP
+       return ioctl(fd, TCSBRKP, d);
+#else
+       return ioctl(fd, TCSBRK, 0);
+#endif
+}
+
+static inline int tcflow(int fd, int a)
+{
+       return ioctl(fd, TCXONC, a);
+}
+
+static inline pid_t tcgetsid(int fd)
+{
+       pid_t sid;
+
+       if (ioctl(fd, TIOCGSID, &sid) < 0)
+               return (pid_t)-1;
+
+       return sid;
+}
+
+static inline speed_t cfgetospeed(const struct termios *t)
+{
+       return t->c_cflag & CBAUD;
+}
+
+static inline int cfsetospeed(struct termios *t, speed_t s)
+{
+       if (s & ~CBAUD) {
+               errno = EINVAL;
+               return -1;
+       }
+
+       t->c_cflag &= ~CBAUD;
+       t->c_cflag |= s;
+
+       return 0;
+}
+
+#ifdef IBSHIFT
+static inline speed_t cfgetispeed(const struct termios *t)
+{
+       speed_t s = (t->c_cflag >> IBSHIFT) & CBAUD;
+
+       if (s == B0)
+               return cfgetospeed(t);
+       else
+               return s;
+}
+
+static inline int cfsetispeed(struct termios *t, speed_t s)
+{
+       if (s == 0)
+               s = B0;
+
+       if (s & ~CBAUD) {
+               errno = EINVAL;
+               return -1;
+       }
+
+       t->c_cflag &= ~(CBAUD << IBSHIFT);
+       t->c_cflag |= s << IBSHIFT;
+
+       return 0;
+}
+#else /* !IBSHIFT */
+static inline speed_t cfgetispeed(const struct termios *t)
+{
+       return cfgetospeed(t);
+}
+
+static inline int cfsetispeed(struct termios *t, speed_t s)
+{
+       return cfsetospeed(t, s);
+}
+#endif /* !IBSHIFT */
+
+static inline int cfsetspeed(struct termios *t, speed_t s)
+{
+       if (cfsetospeed(t, s))
+               return -1;
+#ifdef IBSHIFT
+       if (cfsetispeed(t, s))
+               return -1;
+#endif
+
+       return 0;
+}
+
+static void cfmakeraw(struct termios *t)
+{
+       t->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR |
+                       ICRNL | IXON);
+       t->c_oflag &= ~OPOST;
+       t->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
+       t->c_cflag &= ~(CSIZE | PARENB);
+       t->c_cflag |= CS8;
+}
+
+#endif /* _TERMIOS_LINUX_H_ */