[PATCH in main] vfs: use fchmod for _fixfilemode

[Adrian Buehlmann]

On 2012-10-13 00:19, Adrian Buehlmann wrote:
> # HG changeset patch
> # User Matt Mackall <mpm at selenic.com>
> # Date 1350014314 18000
> # Node ID 76b73ce0ffaca8b562747564ce89f4798b2275e5
> # Parent  4871c1f343fae9f38b9dc9600ab96f2017d116ce
> vfs: use fchmod for _fixfilemode
> 
> On general principle, we should use fchmod instead of chmod to avoid
> security pitfalls, although none is likely possible here.
> 
> diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
> --- a/mercurial/scmutil.py
> +++ b/mercurial/scmutil.py
> @@ -255,10 +255,10 @@
>      def _cansymlink(self):
>          return util.checklink(self.base)
>  
> -    def _fixfilemode(self, name):
> +    def _fixfilemode(self, fp):
>          if self.createmode is None:
>              return
> -        os.chmod(name, self.createmode & 0666)
> +        os.fchmod(fp.fileno(), self.createmode & 0666)
>  
>      def __call__(self, path, mode="r", text=False, atomictemp=False):
>          if self._audit:
> @@ -305,7 +305,7 @@
>                      util.rename(util.mktempcopy(f), f)
>          fp = util.posixfile(f, mode)
>          if nlink == 0:
> -            self._fixfilemode(f)
> +            self._fixfilemode(fp)
>          return fp
>  
>      def symlink(self, src, dst):
> @@ -329,8 +329,8 @@
>          else:
>              f = self(dst, "w")
>              f.write(src)
> +            self._fixfilemode(f)
>              f.close()
> -            self._fixfilemode(dst)
>  
>      def audit(self, path):
>          self.auditor(path)

http://docs.python.org/library/os.html#os.fchmod

"""
os.fchmod(fd, mode)
Change the mode of the file given by fd to the numeric mode. See the
docs for chmod() for possible values of mode.

Availability: Unix.

New in version 2.6.
"""