FileUtils.touch not consistent with system('touch')

ruby-talk
1

Hi,

I have a world-writable file, not owned by me, that I try to touch:

-rwxrwxrwx 1 root root 0 Oct 11 10:29 /tmp/file

ruby -rfileutils -e 'FileUtils.touch("/tmp/file")'
/usr/lib/ruby/1.8/fileutils.rb:1014:in `utime': Operation not
permitted - /tmp/file (Errno::EPERM)
        from /usr/lib/ruby/1.8/fileutils.rb:1014:in `touch'
        from /usr/lib/ruby/1.8/fileutils.rb:1012:in `touch'
        from -e:1

but:
ruby -e 'system("touch /tmp/file")'

succeeds.

The reason is that File.utime cannot be called with a NULL argument.
Linux (and I assume this is Posix) allows a utime call with NULL if
the file is writeable,
but to change the time a process must have special privileges.
With the current File.utime FileUtils cannot implement this.

Cheers,

Han Holl

2

Hi,

At Wed, 11 Oct 2006 17:37:05 +0900,
Han Holl wrote in [ruby-talk:219037]:

The reason is that File.utime cannot be called with a NULL argument.
Linux (and I assume this is Posix) allows a utime call with NULL if
the file is writeable,
but to change the time a process must have special privileges.
With the current File.utime FileUtils cannot implement this.

What about this?

Index: file.c

···

===================================================================
RCS file: /pub/cvs/ruby/file.c,v
retrieving revision 1.253
diff -U 2 -p -r1.253 file.c
--- file.c 25 Sep 2006 12:25:03 -0000 1.253
+++ file.c 11 Oct 2006 08:53:57 -0000
@@ -1966,11 +1966,14 @@ rb_file_s_utime(int argc, VALUE *argv)
{
     VALUE atime, mtime, rest;
- struct timeval tvp[2];
+ struct timeval tvs[2], *tvp = NULL;
     long n;

     rb_scan_args(argc, argv, "2*", &atime, &mtime, &rest);

- tvp[0] = rb_time_timeval(atime);
- tvp[1] = rb_time_timeval(mtime);
+ if (!NIL_P(atime) || !NIL_P(mtime)) {
+ tvp = tvs;
+ tvp[0] = rb_time_timeval(atime);
+ tvp[1] = rb_time_timeval(mtime);
+ }

     n = apply2files(utime_internal, rest, tvp);
@@ -2001,14 +2004,17 @@ rb_file_s_utime(int argc, VALUE *argv)
     long n;
     struct timeval tv;
- struct utimbuf utbuf;
+ struct utimbuf utbuf, *utp = NULL;

     rb_scan_args(argc, argv, "2*", &atime, &mtime, &rest);

- tv = rb_time_timeval(atime);
- utbuf.actime = tv.tv_sec;
- tv = rb_time_timeval(mtime);
- utbuf.modtime = tv.tv_sec;
+ if (!NIL_P(atime) || !NIL_P(mtime)) {
+ utp = &utbuf;
+ tv = rb_time_timeval(atime);
+ utp->actime = tv.tv_sec;
+ tv = rb_time_timeval(mtime);
+ utp->modtime = tv.tv_sec;
+ }

- n = apply2files(utime_internal, rest, &utbuf);
+ n = apply2files(utime_internal, rest, utp);
     return LONG2FIX(n);
}
@@ -2924,4 +2930,9 @@ rb_file_join(VALUE ary, VALUE sep)
       }
       else if (!*tail) {
+#ifdef DOSISH_DRIVE_LETTER
+ if ((tail - name == 2) && has_drive_letter(name)) {
+ rb_str_buf_cat(result, ".", 1);
+ }
+#endif
     rb_str_buf_append(result, sep);
       }
Index: lib/fileutils.rb

RCS file: /pub/cvs/ruby/lib/fileutils.rb,v
retrieving revision 1.73
diff -U 2 -p -r1.73 fileutils.rb
--- lib/fileutils.rb 9 Oct 2006 14:41:24 -0000 1.73
+++ lib/fileutils.rb 11 Oct 2006 09:02:41 -0000
@@ -1008,14 +1008,21 @@ module FileUtils
     fu_check_options options, OPT_TABLE['touch']
     list = fu_list(list)
- fu_output_message "touch #{list.join ' '}" if options[:verbose]
+ if options[:verbose]
+ fu_output_message "touch #{options[:nocreate] ? ' -c' :
''}#{options[:mtime] ? options[:mtime].strftime(' -t %Y%m%d%H%M.%S') :
''}#{list.join ' '}"
+ end
     return if options[:noop]
- t = Time.now
+ created = nocreate = options[:nocreate]
+ t = options[:mtime]
     list.each do |path|
+ created = nocreate
       begin
         File.utime(t, t, path)
       rescue Errno::ENOENT
+ raise unless created
         File.open(path, 'a') {
           ;
         }
+ created = true
+ retry if t
       end
     end
@@ -1023,5 +1030,5 @@ module FileUtils
   module_function :touch

- OPT_TABLE['touch'] = [:noop, :verbose]
+ OPT_TABLE['touch'] = [:noop, :verbose, :mtime, :nocreate]

   private

--
Nobu Nakada

3

Hi,

At Wed, 11 Oct 2006 19:08:36 +0900,
Nobuyoshi Nakada wrote in [ruby-talk:219042]:

Index: lib/fileutils.rb

RCS file: /pub/cvs/ruby/lib/fileutils.rb,v
retrieving revision 1.73
diff -U 2 -p -r1.73 fileutils.rb

+ raise unless created

Sorry, should be `if' but not `unless'.

···

--
Nobu Nakada

4

Hi,

  In mail "Re: FileUtils.touch not consistent with system('touch')"

···

"Nobuyoshi Nakada" <nobu@ruby-lang.org> wrote:

> The reason is that File.utime cannot be called with a NULL argument.
> Linux (and I assume this is Posix) allows a utime call with NULL if
> the file is writeable,
> but to change the time a process must have special privileges.
> With the current File.utime FileUtils cannot implement this.

What about this?

Index: lib/fileutils.rb

This part seems nice, please commit it after File.utime
patch is committed.

Best Regards,
Minero Aoki

5

Hi,

At Wed, 11 Oct 2006 19:08:36 +0900,
Nobuyoshi Nakada wrote in [ruby-talk:219042]:

> Linux (and I assume this is Posix) allows a utime call with NULL if
> the file is writeable,

rb_w32_utime() didn't support it.

I'm not sure it should be LocalFileTime or not.

Index: win32/win32.c

···

===================================================================
RCS file: /pub/cvs/ruby/win32/win32.c,v
retrieving revision 1.195
diff -U 2 -p -r1.195 win32.c
--- win32/win32.c 12 Aug 2006 06:56:09 -0000 1.195
+++ win32/win32.c 12 Oct 2006 04:50:36 -0000
@@ -4118,9 +4118,15 @@ rb_w32_utime(const char *path, const str
     }

- if (unixtime_to_filetime(times->actime, &atime)) {
- return -1;
+ if (times) {
+ if (unixtime_to_filetime(times->actime, &atime)) {
+ return -1;
+ }
+ if (unixtime_to_filetime(times->modtime, &mtime)) {
+ return -1;
+ }
     }
- if (unixtime_to_filetime(times->modtime, &mtime)) {
- return -1;
+ else {
+ GetSystemTimeAsFileTime(&atime);
+ mtime = atime;
     }

--
Nobu Nakada