Linux has supported arbitrary speeds and split speeds in the kernel
since 2008 on all platforms except Alpha (fixed in 2020), but glibc
was never updated to match. This is further complicated by POSIX uses
of macros for the cf[gs]et[io]speed interfaces, rather than plain
numbers, as it really ought to have.
On most platforms, the glibc ABI includes the c_[io]speed fields in
struct termios, but they are incorrectly used. On MIPS and SPARC, they
are entirely missing.
For backwards compatibility, the kernel will still use the legacy
speed fields unless they are set to BOTHER, and will use the legacy
output speed as the input speed if the latter is 0 (== B0). However,
the specific encoding used is visible to user space applications,
including ones other than the one running.
- SPARC and MIPS get a new struct termios, and tc[gs]etattr() is
versioned accordingly. However, the new struct termios is set to be
a strict extension of the old one, which means that cf* interfaces
other than the speed-related ones do not need versioning.
- The Bxxx constants are redefined as equivalent to their integer
values and the legacy Bxxx constants are renamed __Bxxx.
- cf[gs]et[io]speed() and cfsetspeed() are versioned accordingly.
- tcgetattr() and cfset[io]speed() are adjusted to always keep the
c_[io]speed fields correct (unlike earlier versions), but to
canonicalize the representation to ALSO configure the legacy fields
if a valid legacy representation exists.
- tcsetattr(), too, canonicalizes the representation in this way
before passing it to the kernel, to maximize compatibility with
older applications/tools.
- The old IBAUD0 hack is removed; it is no longer necessary since
even the legacy c_cflag baud rate fields have had separate input
values for a long time.
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Linux 6.0 adds a constant ADDRB, a termios c_cflag bit, to its
include/uapi/asm-generic/termbits-common.h.
Add it accordingly to glibc's bits/termios-c_cflag.h headers. As
other constants in these headers are generally in octal, I converted
the value to octal to match. As ADDRB isn't in a POSIX-reserved
namespace, I made it conditional on __USE_MISC.
Tested for x86_64.
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.
I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah. I don't
know why I run into these diagnostics whereas others evidently do not.
remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
This patch consolidates the termios symbolic constants used for output
mode with c_cflag memver on its own header. The Linux generic
implementation values match the kernel UAPI and each architecture with
deviate values have their own implementation (in this case alpha and
powerpc).
No semantic change is expected, checked on a build against x86_64-linux-gnu,
alpha-linux-gnu, mips64-linux-gnu, and sparc64-linux-gnu.
* sysdeps/unix/sysv/linux/Makefile (sysdep_headers): Add
termios-c_cflag.h.
* sysdeps/unix/sysv/linux/bits/termios-c_cflag.h: New file.
* sysdeps/unix/sysv/linux/alpha/bits/termios-c_cflag.h: Likewise.
* sysdeps/unix/sysv/linux/powerpc/bits/termios-c_cflag.h: Likewise.
* sysdeps/unix/sysv/linux/bits/termios.h (CSIZE, CS5, CS6, CS7, CS8,
CSTOPB, CREAD, PARENB, PARODD, HUPCL, CLOCAL): Move to
termios-c_cflag.h.
* sysdeps/unix/sysv/linux/alpha/bits/termios.h: Likewise.
* sysdeps/unix/sysv/linux/mips/bits/termios.h: Likewise.
* sysdeps/unix/sysv/linux/powerpc/bits/termios.h: Likewise.
* sysdeps/unix/sysv/linux/sparc/bits/termios.h: Likewise.
