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comp.lang.ruby

FileUtils.touch not consistent with system('touch'

Han Holl

10/11/2006 8:37:00 AM

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

4 Answers

Nobuyoshi Nakada

10/11/2006 10:09:00 AM

0

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

Nobuyoshi Nakada

10/11/2006 10:42:00 AM

0

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

Minero Aoki

10/11/2006 7:13:00 PM

0

Nobuyoshi Nakada

10/12/2006 5:36:00 AM

0

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