Paul Brannan created THRIFT-2182:
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Summary: segfault in regression tests (GC bug in
rb_thrift_memory_buffer_write)
Key: THRIFT-2182
URL: https://issues.apache.org/jira/browse/THRIFT-2182
Project: Thrift
Issue Type: Bug
Components: Ruby - Library
Affects Versions: 0.9.1, 0.9.2
Reporter: Paul Brannan
This bug causes the regression tests to segfault on my machine. As this is a
GC bug, it may or may not be easily reproducible.
The rb_thrift_memory_buffer_write function looks like this:
VALUE rb_thrift_memory_buffer_write(VALUE self, VALUE str) {
VALUE buf = GET_BUF(self);
str = force_binary_encoding(str);
rb_str_buf_cat(buf, RSTRING_PTR(str), RSTRING_LEN(str));
return Qnil;
}
When gcc compiles this, it optimizes away the value of str (it is no longer
used after RSTRING_PTR(str) and RSTRING_LEN(str) are computed). Later,
rb_str_buf_cat invokes the GC, and the string referenced by str is collected,
because there are no references to it on the stack.
Some possible solutions:
* Use StringValuePtr instead of RSTRING_PTR (in general RSTRING_PTR should be
avoided in favor of StringValuePtr or StringValueCStr); I believe this will
also fix #THRIFT-1047
* Use rb_str_cat instead of rb_str_buf_cat
* Use RB_GC_GUARD to prevent str from getting collected
It appears a similar bug may exist with buffer_value in
rb_thrift_memory_buffer_read_into_buffer, and possibly in any of the other 30
places that RSTRING_PTR is used.
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