Re: new cmp -i 99999999999999999999 failure

[Jim Meyering]

On Sun, Jun 25, 2023 at 3:49 PM Jim Meyering <jim@meyering.net> wrote:
>
> On Sun, Jun 25, 2023 at 3:33 PM Paul Eggert <eggert@cs.ucla.edu> wrote:
> > On 2023-06-25 12:26, Jim Meyering wrote:
> > > I was surprised to see your just-added "cmp" test failing, but only on 
> > > Fedora 38.
> > > This would report a difference:
> > >
> > >    echo a>a;echo b>b; src/cmp -i 99999999999999999999 a b
> >
> > Hmm, it doesn't fail for me on Fedora 38 x86-64. uname -a reports:
> >
> > Linux penguin.cs.ucla.edu 6.3.8-200.fc38.x86_64 #1 SMP PREEMPT_DYNAMIC
> > Thu Jun 15 02:15:40 UTC 2023 x86_64 GNU/Linux
> >
> > and 'dnf list glibc' says it's 2.37-4.fc38.
>
>   $ rpm -q glibc
>   glibc-2.37-4.fc38.x86_64
>
> uname -a shows this: 6.2.15-300.fc38.x86_64

I saw your kernel is slightly older, so rebooted into the latest,
which is the same as yours, backed out our two latest patches and am
still seeing those failing lseeks:

$ echo a>a;echo b>b; strace -eopenat,read,lseek src/cmp -i
99999999999999999999 a b
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
openat(AT_FDCWD, "/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0
}\2\0\0\0\0\0"..., 832) = 832
openat(AT_FDCWD, "/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
openat(AT_FDCWD, "/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 3
read(3, "# Locale name alias data base.\n#"..., 4096) = 2998
read(3, "", 4096)                       = 0
openat(AT_FDCWD, "/usr/lib/locale/en_US.UTF-8/LC_TIME",
O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/locale/en_US.utf8/LC_TIME", O_RDONLY|O_CLOEXEC) = 3
openat(AT_FDCWD, "/usr/lib64/gconv/gconv-modules.cache", O_RDONLY) = 3
openat(AT_FDCWD,
"/p/share/locale/en_US.UTF-8/LC_MESSAGES/diffutils.mo", O_RDONLY) = -1
ENOENT (No such file or directory)
openat(AT_FDCWD,
"/p/share/locale/en_US.utf8/LC_MESSAGES/diffutils.mo", O_RDONLY) = -1
ENOENT (No such file or directory)
openat(AT_FDCWD, "/p/share/locale/en_US/LC_MESSAGES/diffutils.mo",
O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/p/share/locale/en.UTF-8/LC_MESSAGES/diffutils.mo",
O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/p/share/locale/en.utf8/LC_MESSAGES/diffutils.mo",
O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/p/share/locale/en/LC_MESSAGES/diffutils.mo",
O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/proc/self/maps", O_RDONLY) = 3
lseek(3, 0, SEEK_SET)                   = 0
read(3, "00400000-00402000 r--p 00000000 "..., 8192) = 2430
read(3, "", 5762)                       = 0
openat(AT_FDCWD, "a", O_RDONLY)         = 3
openat(AT_FDCWD, "b", O_RDONLY)         = 4
lseek(3, 9223372036854775807, SEEK_CUR) = -1 EINVAL (Invalid argument)
read(3, 0x187de50, 18446744073709551615) = -1 EFAULT (Bad address)
lseek(4, 9223372036854775807, SEEK_CUR) = -1 EINVAL (Invalid argument)
read(4, 0x187de50, 18446744073709551615) = -1 EFAULT (Bad address)
read(3, "a\n", 4096)                    = 2
read(3, "", 4094)                       = 0
read(4, "b\n", 4096)                    = 2
read(4, "", 4094)                       = 0
a b differ: byte 1, line 1
+++ exited with 1 +++

I also rebuilt with CC=/bin/gcc, in case my using a recent snapshot
caused trouble. Same result.