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Re: [PATCH] Linux: Define struct termios2 in <termios.h> under _GNU_SOURCE [BZ #10339]


On April 9, 2019 4:47:30 AM MDT, Florian Weimer <fweimer@redhat.com> wrote:
>struct termios2 is required for setting arbitrary baud rates on serial
>ports.  <sys/ioctl.h> and <linux/termios.h> have conflicting
>definitions in the existing termios definitions, which means that it
>is currently very difficult to use TCGETS2/TCSETS2 and struct termios2
>with glibc.  Providing a definition within glibc resolves this problem.
>
>This does not completely address bug 10339, but it at least exposes
>the current kernel functionality in this area.
>
>Support for struct termios2 is architecture-specific in the kernel.
>Support on alpha was only added in Linux 4.20.  POWER support is
>currently missing.  The expectation is that the kernel will eventually
>use the generic UAPI definition for struct termios2.
>
>2019-04-09  Florian Weimer  <fweimer@redhat.com>
>
>	[BZ #10339]
>	Linux: Define struct termios2 in <termios.h> under _GNU_SOURCE.
>	* sysdeps/unix/sysv/linux/Makefile [$(subdir) == termios] (tests):
>	Add tst-termios2.
>	* sysdeps/unix/sysv/linux/tst-termios2.c: New file.
>	* sysdeps/unix/sysv/linux/bits/termios2-struct.h: Likewise.
>	* sysdeps/unix/sysv/linux/bits/termios.h [__USE_GNU]: Include it.
>	* sysdeps/unix/sysv/linux/alpha/bits/termios2-struct.h: New file.
>	* sysdeps/unix/sysv/linux/sparc/bits/termios2-struct.h: Likewise.
>
>diff --git a/NEWS b/NEWS
>index b58e2469d4..5e6ecb9c7d 100644
>--- a/NEWS
>+++ b/NEWS
>@@ -18,6 +18,9 @@ Major new features:
> 
> * On Linux, the gettid function has been added.
> 
>+* On Linux, <termios.h> now provides a definition of struct termios2
>with
>+  the _GNU_SOURCE feature test macro.
>+
> * Minguo (Republic of China) calendar support has been added as an
> alternative calendar for the following locales: zh_TW, cmn_TW, hak_TW,
>   nan_TW, lzh_TW.
>diff --git a/sysdeps/unix/sysv/linux/Makefile
>b/sysdeps/unix/sysv/linux/Makefile
>index 52ac6ad484..4cb5e4f0d2 100644
>--- a/sysdeps/unix/sysv/linux/Makefile
>+++ b/sysdeps/unix/sysv/linux/Makefile
>@@ -156,6 +156,7 @@ endif
> 
> ifeq ($(subdir),termios)
> sysdep_headers += termio.h
>+tests += tst-termios2
> endif
> 
> ifeq ($(subdir),posix)
>diff --git a/sysdeps/unix/sysv/linux/alpha/bits/termios2-struct.h
>b/sysdeps/unix/sysv/linux/alpha/bits/termios2-struct.h
>new file mode 100644
>index 0000000000..5f09445e23
>--- /dev/null
>+++ b/sysdeps/unix/sysv/linux/alpha/bits/termios2-struct.h
>@@ -0,0 +1,33 @@
>+/* struct termios2 definition.  Linux/alpha version.
>+   Copyright (C) 2019 Free Software Foundation, Inc.
>+   This file is part of the GNU C Library.
>+
>+   The GNU C Library is free software; you can redistribute it and/or
>+   modify it under the terms of the GNU Lesser General Public
>+   License as published by the Free Software Foundation; either
>+   version 2.1 of the License, or (at your option) any later version.
>+
>+   The GNU C Library is distributed in the hope that it will be
>useful,
>+   but WITHOUT ANY WARRANTY; without even the implied warranty of
>+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+   Lesser General Public License for more details.
>+
>+   You should have received a copy of the GNU Lesser General Public
>+   License along with the GNU C Library.  If not, see
>+   <http://www.gnu.org/licenses/>.  */
>+
>+#ifndef _TERMIOS_H
>+# error "Never include <bits/termios2-struct.h> directly; use
><termios.h> instead."
>+#endif
>+
>+struct termios2
>+{
>+  tcflag_t c_iflag;
>+  tcflag_t c_oflag;
>+  tcflag_t c_cflag;
>+  tcflag_t c_lflag;
>+  cc_t c_cc[NCCS];
>+  cc_t c_line;
>+  speed_t c_ispeed;
>+  speed_t c_ospeed;
>+};
>diff --git a/sysdeps/unix/sysv/linux/bits/termios.h
>b/sysdeps/unix/sysv/linux/bits/termios.h
>index 997231cd03..45ac7affdf 100644
>--- a/sysdeps/unix/sysv/linux/bits/termios.h
>+++ b/sysdeps/unix/sysv/linux/bits/termios.h
>@@ -25,6 +25,10 @@ typedef unsigned int	speed_t;
> typedef unsigned int	tcflag_t;
> 
> #include <bits/termios-struct.h>
>+#ifdef __USE_GNU
>+# include <bits/termios2-struct.h>
>+#endif
>+
> #include <bits/termios-c_cc.h>
> #include <bits/termios-c_iflag.h>
> #include <bits/termios-c_oflag.h>
>diff --git a/sysdeps/unix/sysv/linux/bits/termios2-struct.h
>b/sysdeps/unix/sysv/linux/bits/termios2-struct.h
>new file mode 100644
>index 0000000000..5a48e45ef3
>--- /dev/null
>+++ b/sysdeps/unix/sysv/linux/bits/termios2-struct.h
>@@ -0,0 +1,33 @@
>+/* struct termios2 definition.  Linux/generic version.
>+   Copyright (C) 2019 Free Software Foundation, Inc.
>+   This file is part of the GNU C Library.
>+
>+   The GNU C Library is free software; you can redistribute it and/or
>+   modify it under the terms of the GNU Lesser General Public
>+   License as published by the Free Software Foundation; either
>+   version 2.1 of the License, or (at your option) any later version.
>+
>+   The GNU C Library is distributed in the hope that it will be
>useful,
>+   but WITHOUT ANY WARRANTY; without even the implied warranty of
>+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+   Lesser General Public License for more details.
>+
>+   You should have received a copy of the GNU Lesser General Public
>+   License along with the GNU C Library.  If not, see
>+   <http://www.gnu.org/licenses/>.  */
>+
>+#ifndef _TERMIOS_H
>+# error "Never include <bits/termios2-struct.h> directly; use
><termios.h> instead."
>+#endif
>+
>+struct termios2
>+{
>+  tcflag_t c_iflag;
>+  tcflag_t c_oflag;
>+  tcflag_t c_cflag;
>+  tcflag_t c_lflag;
>+  cc_t c_line;
>+  cc_t c_cc[NCCS];
>+  speed_t c_ispeed;
>+  speed_t c_ospeed;
>+};
>diff --git a/sysdeps/unix/sysv/linux/sparc/bits/termios2-struct.h
>b/sysdeps/unix/sysv/linux/sparc/bits/termios2-struct.h
>new file mode 100644
>index 0000000000..7c889e575c
>--- /dev/null
>+++ b/sysdeps/unix/sysv/linux/sparc/bits/termios2-struct.h
>@@ -0,0 +1,33 @@
>+/* struct termios2 definition.  Linux/sparc version.
>+   Copyright (C) 2019 Free Software Foundation, Inc.
>+   This file is part of the GNU C Library.
>+
>+   The GNU C Library is free software; you can redistribute it and/or
>+   modify it under the terms of the GNU Lesser General Public
>+   License as published by the Free Software Foundation; either
>+   version 2.1 of the License, or (at your option) any later version.
>+
>+   The GNU C Library is distributed in the hope that it will be
>useful,
>+   but WITHOUT ANY WARRANTY; without even the implied warranty of
>+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+   Lesser General Public License for more details.
>+
>+   You should have received a copy of the GNU Lesser General Public
>+   License along with the GNU C Library.  If not, see
>+   <http://www.gnu.org/licenses/>.  */
>+
>+#ifndef _TERMIOS_H
>+# error "Never include <bits/termios2-struct.h> directly; use
><termios.h> instead."
>+#endif
>+
>+struct termios2
>+{
>+  tcflag_t c_iflag;
>+  tcflag_t c_oflag;
>+  tcflag_t c_cflag;
>+  tcflag_t c_lflag;
>+  cc_t c_line;
>+  cc_t c_cc[NCCS + 2];
>+  speed_t c_ispeed;
>+  speed_t c_ospeed;
>+};
>diff --git a/sysdeps/unix/sysv/linux/tst-termios2.c
>b/sysdeps/unix/sysv/linux/tst-termios2.c
>new file mode 100644
>index 0000000000..82326a1288
>--- /dev/null
>+++ b/sysdeps/unix/sysv/linux/tst-termios2.c
>@@ -0,0 +1,48 @@
>+/* Minimal test of struct termios2 definition.
>+   Copyright (C) 2019 Free Software Foundation, Inc.
>+   This file is part of the GNU C Library.
>+
>+   The GNU C Library is free software; you can redistribute it and/or
>+   modify it under the terms of the GNU Lesser General Public
>+   License as published by the Free Software Foundation; either
>+   version 2.1 of the License, or (at your option) any later version.
>+
>+   The GNU C Library is distributed in the hope that it will be
>useful,
>+   but WITHOUT ANY WARRANTY; without even the implied warranty of
>+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+   Lesser General Public License for more details.
>+
>+   You should have received a copy of the GNU Lesser General Public
>+   License along with the GNU C Library.  If not, see
>+   <http://www.gnu.org/licenses/>.  */
>+
>+#include <termios.h>
>+#include <sys/ioctl.h>
>+
>+/* This function is never executed, but must be compiled successfully.
>+   Accessing serial ports in the test suite is problematic because
>+   they likely correspond with low-level system functionality.  */
>+void
>+not_executed (int fd)
>+{
>+  /* Avoid a compilation failure if TCGETS2, TCSETS2 are not
>+     defined.  */
>+#if defined (TCGETS2) && defined (TCSETS2)
>+  struct termios2 ti;
>+  ioctl (fd, TCGETS2, &ti);
>+  ioctl (fd, TCSETS2, &ti);
>+#endif
>+}
>+
>+static int
>+do_test (void)
>+{
>+  /* Fail at run time if TCGETS2 or TCSETS2 is not defined.  */
>+#if defined (TCGETS2) && defined (TCSETS2)
>+  return 0;
>+#else
>+  return 1;
>+#endif
>+}
>+
>+#include <support/test-driver.c>

Anything blocking the POC code I provided?

Note: for PowerPC, define termios2 = kernel termios, and the ioctls as aliases.
-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.


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