[Guile-commits] 03/06: Remove 'umask' calls from 'mkdir'.

[Andy Wingo]

wingo pushed a commit to branch master
in repository guile.

commit 844b2cf7586c31c01ab8e255d8a21aa836b7ff0b
Author: Ludovic Courtès <address@hidden>
Date:   Tue Oct 11 10:14:26 2016 +0200

    Remove 'umask' calls from 'mkdir'.
    
    Fixes <http://bugs.gnu.org/24659>.
    
    * libguile/filesys.c (SCM_DEFINE): Remove calls to 'umask' when MODE is
    unbound; instead, use 0777 as the mode.  Update docstring to clarify
    this.
    * doc/ref/posix.texi (File System): Adjust accordingly.
    * NEWS: Mention it.
---
 NEWS               | 14 +++++++++++++-
 doc/ref/posix.texi |  7 ++++---
 libguile/filesys.c | 25 ++++++++++---------------
 3 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/NEWS b/NEWS
index 2126813..7fa279a 100644
--- a/NEWS
+++ b/NEWS
@@ -996,9 +996,21 @@ Changes in 2.0.13 (since 2.0.12):
 See "File System" in the manual, for more.
 
 * Bug fixes
+
+** 'mkdir' procedure no longer calls umask(2) (<http://bugs.gnu.org/24659>)
+
+When the second argument to the 'mkdir' procedure was omitted, it would
+call umask(0) followed by umask(previous_umask) and apply the umask to
+mode #o777.
+
+This was unnecessary and a security issue for multi-threaded
+applications: during a small window the process' umask was set to zero,
+so other threads calling mkdir(2) or open(2) could end up creating
+world-readable/writable/executable directories or files.
+
 ** Fix optimizer bug when compiling fixpoint operator
 ** Fix build error on MinGW
-** Update `uname' implementation on MinGW
+** Update 'uname' implementation on MinGW
 
 
 Changes in 2.0.12 (since 2.0.11):
diff --git a/doc/ref/posix.texi b/doc/ref/posix.texi
index 6f9ce54..64e668d 100644
--- a/doc/ref/posix.texi
+++ b/doc/ref/posix.texi
@@ -870,9 +870,10 @@ Create a symbolic link named @var{newpath} with the value 
(i.e., pointing to)
 @deffn {Scheme Procedure} mkdir path [mode]
 @deffnx {C Function} scm_mkdir (path, mode)
 Create a new directory named by @var{path}.  If @var{mode} is omitted
-then the permissions of the directory file are set using the current
-umask (@pxref{Processes}).  Otherwise they are set to the decimal
-value specified with @var{mode}.  The return value is unspecified.
+then the permissions of the directory are set to @code{#o777}
+masked with the current umask (@pxref{Processes, @code{umask}}).
+Otherwise they are set to the value specified with @var{mode}.
+The return value is unspecified.
 @end deffn
 
 @deffn {Scheme Procedure} rmdir path
diff --git a/libguile/filesys.c b/libguile/filesys.c
index 478369d..f185601 100644
--- a/libguile/filesys.c
+++ b/libguile/filesys.c
@@ -1,5 +1,5 @@
 /* Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2004, 2006,
- *   2009, 2010, 2011, 2012, 2013, 2014 Free Software Foundation, Inc.
+ *   2009, 2010, 2011, 2012, 2013, 2014, 2016 Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -1258,26 +1258,21 @@ SCM_DEFINE (scm_getcwd, "getcwd", 0, 0, 0,
 SCM_DEFINE (scm_mkdir, "mkdir", 1, 1, 0,
             (SCM path, SCM mode),
            "Create a new directory named by @var{path}.  If @var{mode} is 
omitted\n"
-           "then the permissions of the directory file are set using the 
current\n"
-           "umask.  Otherwise they are set to the decimal value specified 
with\n"
-           "@var{mode}.  The return value is unspecified.")
+           "then the permissions of the directory are set to @code{#o777}\n"
+           "masked with the current umask (@pxref{Processes, @code{umask}}).\n"
+           "Otherwise they are set to the value specified with @var{mode}.\n"
+           "The return value is unspecified.")
 #define FUNC_NAME s_scm_mkdir
 {
   int rv;
-  mode_t mask;
+  mode_t c_mode;
 
-  if (SCM_UNBNDP (mode))
-    {
-      mask = umask (0);
-      umask (mask);
-      STRING_SYSCALL (path, c_path, rv = mkdir (c_path, 0777 ^ mask));
-    }
-  else
-    {
-      STRING_SYSCALL (path, c_path, rv = mkdir (c_path, scm_to_uint (mode)));
-    }
+  c_mode = SCM_UNBNDP (mode) ? 0777 : scm_to_uint (mode);
+
+  STRING_SYSCALL (path, c_path, rv = mkdir (c_path, c_mode));
   if (rv != 0)
     SCM_SYSERROR;
+
   return SCM_UNSPECIFIED;
 }
 #undef FUNC_NAME