[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#24659: 'mkdir' procedure is neither thread-safe nor safe (2.0.12)
From: |
Ludovic Courtès |
Subject: |
bug#24659: 'mkdir' procedure is neither thread-safe nor safe (2.0.12) |
Date: |
Mon, 10 Oct 2016 18:39:47 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) |
Hello!
When the optional ‘mode’ argument to the ‘mkdir’ procedure is omitted,
umask(2) is used to find out what the current mask is and to compute the
mode argument to mkdir(2):
--8<---------------cut here---------------start------------->8---
if (SCM_UNBNDP (mode))
{
mask = umask (0);
umask (mask);
STRING_SYSCALL (path, c_path, rv = mkdir (c_path, 0777 ^ mask));
}
--8<---------------cut here---------------end--------------->8---
The problem is that this changes the process’ umask globally for a short
duration, during which other threads will get 0 as the mask…
Furthermore, AFAICS, the above logic is redundant with what the kernel
does anyway. That is, in a single-threaded program,
mask = umask (0);
umask (mask);
mkdir (file, 0777 ^ mask);
is equivalent to:
mkdir (file, 0777);
Am I right that we should just remove these two ‘umask’ calls?
Ludo’.
PS: This code has been there since 1996 or earlier.
- bug#24659: 'mkdir' procedure is neither thread-safe nor safe (2.0.12),
Ludovic Courtès <=