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Re: Spurious testsuite failures due to multibyte locale
- From: Michael Elizabeth Chastain <mec at shout dot net>
- To: gdb-patches at sources dot redhat dot com, schwab at suse dot de
- Cc: ezannoni at redhat dot com
- Date: Sun, 5 Jan 2003 19:18:43 -0600
- Subject: Re: Spurious testsuite failures due to multibyte locale
Okay, I wrote a standalone test program, it really wasn't painful. :)
I sent a bug report to bug-readline@gnu.org. I can't find a Web link
to it so I am including a copy here for gdb history.
Now the readline maintainers can fix the bug, spin a release, and
Elena Z can pick it up. Meanwhile, we can use the workaround from
Andreas S.
Michael C
===
Synopsis
Readline 4.3 does perverse refresh in UTF-8 mode.
This breaks the gdb automated test suite.
Environment
target = i686-pc-linux-gnu
host = i686-pc-linux-gnu
osversion = red-hat-8.0
gcc = 3.2.1
binutils = 2.13.2.1
libreadline = 4.3
libtermcap = 2.0.8-31-rh
libc = 2.2.93-5-rh
Description
I see perverse screen output. Instead of "(gdb) foo bar", I see
"(gdb) ^M(gdb) f^M(gdb) fo^M(Gdb) foo^M ..." with a carriage return
for each character.
This output style comes as a surprise to all the dejagnu patterns
in the gdb test suite, breaking the test suite. The symptoms are
massive timeouts starting in gdb.base/annota1.exp and continuing
throughout the test suite.
How to Reproduce
Script started on Sun Jan 5 19:56:44 2003
bash-2.05b$ cat z1.c
#include <stdio.h>
#include <readline/readline.h>
int main ()
{
char * line;
for (;;)
{
line = readline ("(prompt) ");
if (line == NULL)
break;
printf ("%s\n", line);
}
printf ("\n");
return 0;
}
bash-2.05b$ gcc -v -g -c z1.c
Reading specs from /berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1/lib/gcc-lib/i686-pc-linux-gnu/3.2.1/specs
Configured with: /berman/migchain/source/gcc-3.2.1/configure --prefix=/berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1 --disable-shared --with-gnu-as --with-as=/berman/migchain/install/target/native/binutils-2.13.2.1/bin/as --with-gnu-ld --with-ld=/berman/migchain/install/target/native/binutils-2.13.2.1/bin/ld
Thread model: posix
gcc version 3.2.1
/berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1/lib/gcc-lib/i686-pc-linux-gnu/3.2.1/cc1 -lang-c -v -D__GNUC__=3 -D__GNUC_MINOR__=2 -D__GNUC_PATCHLEVEL__=1 -D__GXX_ABI_VERSION=102 -D__ELF__ -Dunix -D__gnu_linux__ -Dlinux -D__ELF__ -D__unix__ -D__gnu_linux__ -D__linux__ -D__unix -D__linux -Asystem=posix -D__NO_INLINE__ -D__STDC_HOSTED__=1 -Acpu=i386 -Amachine=i386 -Di386 -D__i386 -D__i386__ -D__tune_i686__ -D__tune_pentiumpro__ z1.c -quiet -dumpbase z1.c -g -version -o /tmp/cck1itw9.s
GNU CPP version 3.2.1 (cpplib) (i386 Linux/ELF)
GNU C version 3.2.1 (i686-pc-linux-gnu)
compiled by GNU C version 3.2.1.
ignoring nonexistent directory "/berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1/i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/include
/berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1/include
/berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1/lib/gcc-lib/i686-pc-linux-gnu/3.2.1/include
/usr/include
End of search list.
/berman/migchain/install/target/native/binutils-2.13.2.1/bin/as -V -Qy -o z1.o /tmp/cck1itw9.s
GNU assembler version 2.13.2.1 (i686-pc-linux-gnu) using BFD version 2.13.2.1
bash-2.05b$ gcc -v -g -o z1 z1.o ./install/lib/libreadline.a -ltermcap
Reading specs from /berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1/lib/gcc-lib/i686-pc-linux-gnu/3.2.1/specs
Configured with: /berman/migchain/source/gcc-3.2.1/configure --prefix=/berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1 --disable-shared --with-gnu-as --with-as=/berman/migchain/install/target/native/binutils-2.13.2.1/bin/as --with-gnu-ld --with-ld=/berman/migchain/install/target/native/binutils-2.13.2.1/bin/ld
Thread model: posix
gcc version 3.2.1
/berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1/lib/gcc-lib/i686-pc-linux-gnu/3.2.1/collect2 --eh-frame-hdr -m elf_i386 -dynamic-linker /lib/ld-linux.so.2 -o z1 /usr/lib/crt1.o /usr/lib/crti.o /berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1/lib/gcc-lib/i686-pc-linux-gnu/3.2.1/crtbegin.o -L/berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1/lib/gcc-lib/i686-pc-linux-gnu/3.2.1 -L/berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1/lib/gcc-lib/i686-pc-linux-gnu/3.2.1/../../.. z1.o ./install/lib/libreadline.a -ltermcap -lgcc -lc -lgcc /berman/migchain/install/target/native/gcc-3.2.1-binutils-2.13.2.1/lib/gcc-lib/i686-pc-linux-gnu/3.2.1/crtend.o /usr/lib/crtn.o
bash-2.05b$ INPUTRC=/dev/null LANG=en_US ./z1
(prompt) foo
foo
(prompt)
bash-2.05b$ INPUTRC=/dev/null LANG=en_US.UTF-8 ./z1
(prompt)
(prompt)
(prompt) f
(prompt) f
(prompt) fo
(prompt) fo
(prompt) foo
(prompt) foo
foo
(prompt)
(prompt)
bash-2.05b$ exit
Script done on Sun Jan 5 19:58:24 2003
Analysis
It looks like readline/display.c:_rl_move_cursor_relative
has a multibyte bug (MB_CUR_MAX != 1 &&d rl_byte_oriented == 0).
The first optimization "_rl_last_c_pos == new" is disabled
because "_rl_last_c_pos" is a display position but "new"
is an index in a a multibyte string, so they are not comparable.
That is okay. But later on, this block appears:
#if defined (HANDLE_MULTIBYTE)
/* NEW points to the buffer point, but _rl_last_c_pos is the display point.
The byte length of the string is probably bigger than the column width
of the string, which means that if NEW == _rl_last_c_pos, then NEW's
display point is less than _rl_last_c_pos. */
else if (_rl_last_c_pos >= new)
#else
else if (_rl_last_c_pos > new)
#endif
Not so fast, cowboy! _rl_last_c_pos == new here, but all the
characters are plain, so they might match just fine. But readline
pessimizes out and issues a CR and reprints the line every time.
There should be logic here to compare the strings rather than just
assume that a left-move is needed.
Fix
I don't have one.
Workaround
Avoid UTF-8 encoding: "export LANG=en_US" (for en_US people).