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Avoid closing directory we're iterating #42

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d27a455
Revert "Update util.rb to fix closing of file."
ekohl May 1, 2025
8a6bf3e
Avoid closing directory we're iterating
ekohl Mar 5, 2025
3f344ab
Please RuboCop
ekohl Mar 5, 2025
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16 changes: 9 additions & 7 deletions lib/puppet/util.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -478,13 +478,15 @@ def safe_posix_fork(stdin = $stdin, stdout = $stdout, stderr = $stderr, &block)
$stderr = STDERR

begin
Dir.foreach('/proc/self/fd') do |f|
if %{^\d+$}.match?(f) && f.to_i >= 3
begin
IO.new(f.to_i).close
rescue
nil
end
d = Dir.new('/proc/self/fd')
ignore_fds = ['.', '..', d.fileno.to_s]
d.each_child do |f|
next if ignore_fds.include?(f) || f.to_i < 3
Comment on lines +482 to +484
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Looking at #41 I wonder if we should explicitly exclude the FDs that we want to keep open:

Suggested change
ignore_fds = ['.', '..', d.fileno.to_s]
d.each_child do |f|
next if ignore_fds.include?(f) || f.to_i < 3
ignore_fds = ['.', '..', stdin.fileno.to_s, stdout.fileno.to_s, stderr.fileno.to_s, d.fileno.to_s]
d.each_child do |f|
next if ignore_fds.include?(f)

This version is probably safer. Not sure if it's valid to have no stdin, stdout or stderr.

Suggested change
ignore_fds = ['.', '..', d.fileno.to_s]
d.each_child do |f|
next if ignore_fds.include?(f) || f.to_i < 3
ignore_fds = ['.', '..'] + [stdin, stdout, stderr, d].filter_map { |f| f&.fileno&.to_s }
d.each_child do |f|
next if ignore_fds.include?(f)

What makes me hesitant is that I don't know

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I'm a little worried we're playing whack-a-mole with things we want to filter out and I'm not sure how to be sure we're being exhaustive about it.

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IMHO this is much better than looking at .to_i < 3 and assuming that those file descriptors are stdin, stdout and stderr since it is explicit about what's going on.


begin
IO.new(f.to_i).close
rescue
nil
end
end
rescue Errno::ENOENT, Errno::ENOTDIR # /proc/self/fd not found, /proc/self not a dir
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12 changes: 7 additions & 5 deletions spec/unit/util_spec.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -616,18 +616,20 @@ def withenv_utf8(&block)
fds.each do |fd|
if fd == '.' || fd == '..'
next
elsif ['0', '1', '2'].include? fd
elsif ['0', '1', '2', '5'].include? fd
expect(IO).not_to receive(:new).with(fd.to_i)
else
expect(IO).to receive(:new).with(fd.to_i).and_return(double('io', close: nil))
end
end

dir_expectation = receive(:foreach).with('/proc/self/fd')
dir = double(Dir, fileno: '5')
dir_expectation = receive(:each_child)
fds.each do |fd|
dir_expectation = dir_expectation.and_yield(fd)
end
allow(Dir).to dir_expectation
allow(dir).to dir_expectation
allow(Dir).to receive(:new).with('/proc/self/fd').and_return(dir)
Puppet::Util.safe_posix_fork
end

Expand All @@ -636,7 +638,7 @@ def withenv_utf8(&block)
# letting it actually close fds, which seems risky
(0..2).each {|n| expect(IO).not_to receive(:new).with(n)}
(3..256).each {|n| expect(IO).to receive(:new).with(n).and_return(double('io', close: nil)) }
allow(Dir).to receive(:foreach).with('/proc/self/fd').and_raise(Errno::ENOENT)
allow(Dir).to receive(:new).with('/proc/self/fd').and_raise(Errno::ENOENT)

Puppet::Util.safe_posix_fork
end
Expand All @@ -646,7 +648,7 @@ def withenv_utf8(&block)
# letting it actually close fds, which seems risky
(0..2).each {|n| expect(IO).not_to receive(:new).with(n)}
(3..256).each {|n| expect(IO).to receive(:new).with(n).and_return(double('io', close: nil)) }
allow(Dir).to receive(:foreach).with('/proc/self/fd').and_raise(Errno::ENOTDIR)
allow(Dir).to receive(:new).with('/proc/self/fd').and_raise(Errno::ENOTDIR)

Puppet::Util.safe_posix_fork
end
Expand Down