From: Tanaka Akira <akr@...17n.org>
Date: 2002-09-27T00:57:21+09:00
Subject: [ruby-dev:18392] Re: pstore.rb can make a broken store

In article <20020926134339.C8DAE1EE12@milestones.dm4lab.to>,
  YANAGAWA Kazuhisa <kjana@dm4lab.to> writes:

> $BJL$N%U%!%$%k$K=q$$$F(B rename $B$9$k$H$+!$2?$+$b$C$H0BA4$J<jCJ$r$H$k$Y$-$@(B
> $B$H;W$&$N$G$9$,!$$I$&$G$7$g$&$+!%(B
> 
> # $B$@$$$?$$8e$KIU$1$?%Q%C%A$N$h$&$J46$8$G$$$$$N$+$J(B? $B$D$$$G$K(B abort $B$7(B
> # $B$?$H$-(B content $B$r(B unref $B$7$F$J$$$N$bD>$7$F$^$9!%(B

lock $B$7$D$D(B rename $B$H$$$&OC$O$7$P$i$/A0$K9M$($?$3$H$,$"$k$s$G$9$,!"$b(B
$B$&$9$3$7J#;($K$J$k$H;W$$$^$9!#(B

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$B$G$7$g$&$+!#(B

  def open_write(filename)
    dirname = File.dirname filename
    basename = File.basename filename
    tmpname = "#{dirname}/,#{basename},#$$"

    1.times {
      begin
        target = File.open(filename, File::RDWR|File::CREAT)
        stat1 = target.stat
        target.flock(File::LOCK_EX)
        stat2 = File.stat(filename)
        redo if stat1.ino != stat2.ino

        begin
          File.open(tmpname, 'w') {|tmp|
            yield tmp
          }
          stat2 = File.stat(filename)
          File.rename(tmpname, filename) if stat1.ino == stat2.ino
        ensure
          File.unlink tmpname if FileTest.exist? tmpname
        end
      ensure
        target.close
      end
    }
  end

  def open_read(filename, &block)
    File.open(filename, &block)
  end

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-- 
[$BEDCf(B $BE/(B][$B$?$J$+(B $B$"$-$i(B][Tanaka Akira]
$B!V$U$($m(B! $B$o$+$a$A$c$s:n@o$G$9$(C"=$B!W(B(Little Worker, $B7KM7@84](B)