GNU bug report logs -
#71477
30.0.50; Lock files are not deleted on Windows 98
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Reported by: Po Lu <luangruo <at> yahoo.com>
Date: Mon, 10 Jun 2024 16:41:04 UTC
Severity: normal
Found in version 30.0.50
Done: Eli Zaretskii <eliz <at> gnu.org>
Bug is archived. No further changes may be made.
Full log
Message #29 received at 71477 <at> debbugs.gnu.org (full text, mbox):
[Message part 1 (text/plain, inline)]
On 2024-06-12 01:25, Eli Zaretskii wrote:
> - if (! c_isdigit (dot[1]))
> + if (! (c_isdigit (dot[1])
> + /* Windows 9X report negative PID values. */
> + || (dot[1] == '-' && c_isdigit (dot[2]))))
Faster is "if (! c_isdigit[(dot[1] == '-') + 1])", as it avoids a
conditional branch on most platforms.
> - else if (0 < pid && pid <= TYPE_MAXIMUM (pid_t)
> + else if (pid != -1 && pid <= TYPE_MAXIMUM (pid_t)
> && (kill (pid, 0) >= 0 || errno == EPERM)
This looks dubious for most systems, where 'kill' has special behavior
when pid < -1 or pid == 0; it tests a process group. That's not the test
we want here, since we want to check whether Emacs can be sent a signal,
not whether any process in its process group can be sent a signal (this
can be valid even after Emacs has exited). The code should use calls
like kill (-2, 0) and kill (0, 0) only on platforms where we know the
calls do not test a process group.
Even on MS Windows 98 we should check that TYPE_MINIMUM (pid_t) <= pid.
Also, is there a special meaning for kill (0, 0) on MS Windows 98? If
so, we should also check that pid != 0.
Do any MS-Windows platforms support process groups, i.e., kill (-2, 0)
operates on process group 2 rather than on an individual process with
process ID -2? If so, these platforms should be careful too, and should
not use kill (-2, 0) or kill (0, 0).
How about the attached patch instead? You can adjust the
Microsoft-specific .h files to define VALID_PROCESS_ID appropriately for
MS Windows 98, and for any other MS platform where kill (-2, 0) is known
to check for just the individual process -2.
[0001-Start-of-a-fix-for-bug-71477.patch (text/x-patch, attachment)]
This bug report was last modified 1 year and 39 days ago.
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