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fix: prevent segfault in StringIO#seek with SEEK_END on null device #137

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Merged
kou merged 2 commits into from
Aug 9, 2025
Merged

fix: prevent segfault in StringIO#seek with SEEK_END on null device #137

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7a953f4
fix: prevent segfault in StringIO#seek with SEEK_END on null device
koh-sh Aug 9, 2025
ac0ad23
fix: prevent NullPointerException in StringIO#seek with SEEK_END on n…
koh-sh Aug 9, 2025
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6 changes: 5 additions & 1 deletion ext/java/org/jruby/ext/stringio/StringIO.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1378,7 +1378,11 @@ private RubyFixnum seekCommon(ThreadContext context, int argc, IRubyObject arg0,
offset += ptr.pos;
break;
case 2:
offset += ptr.string.size();
if (ptr.string == null) {
offset += 0;
} else {
offset += ptr.string.size();
}
break;
default:
throw runtime.newErrnoEINVALError("invalid whence");
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6 changes: 5 additions & 1 deletion ext/stringio/stringio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -837,7 +837,11 @@ strio_seek(int argc, VALUE *argv, VALUE self)
offset = ptr->pos;
break;
case 2:
offset = RSTRING_LEN(ptr->string);
if (NIL_P(ptr->string)) {
offset = 0;
} else {
offset = RSTRING_LEN(ptr->string);
}
break;
default:
error_inval("invalid whence");
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10 changes: 10 additions & 0 deletions test/stringio/test_stringio.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,16 @@ def test_null
assert_nil io.getc
end

def test_seek_null
io = StringIO.new(nil)
assert_equal(0, io.seek(0, IO::SEEK_SET))
assert_equal(0, io.pos)
assert_equal(0, io.seek(0, IO::SEEK_CUR))
assert_equal(0, io.pos)
assert_equal(0, io.seek(0, IO::SEEK_END)) # This should not segfault
assert_equal(0, io.pos)
end

def test_truncate
io = StringIO.new("")
io.puts "abc"
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