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https://github.com/c64scene-ar/llvm-6502.git
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LLVM backend for 6502
0b8b3ba21e
This is likely only the tip of the ice berg, but this particular bug caused any double-free on a glibc system to turn into a deadlock! It is not generally safe to either allocate or release heap memory from within the signal handler. The 'pop_back()' in RemoveFilesToRemove was deleting memory and causing the deadlock. What's worse, eraseFromDisk in PathV1 has lots of allocation and deallocation paths. We even passed 'true' in a place that would have caused the *signal handler* to try to run the 'system' system call and shell out to 'rm -rf'. That was never going to work... This patch switches the file removal to use a vector of strings so that the exact text needed for the 'unlink' system call can be stored there. It switches the loop to be a boring indexed loop, and directly calls unlink without looking at the error. It also works quite hard to ensure that calling 'c_str()' is safe, by ensuring that the non-signal-handling code path that manipulates the vector always leaves it in a state where every element has already had 'c_str()' called at least once. I dunno exactly how overkill this is, but it fixes the deadlock-on-double free issue, and seems likely to prevent any other issues from sneaking up. Sorry for not having a test case, but I *really* don't know how to test signal handling code easily.... git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158580 91177308-0d34-0410-b5e6-96231b3b80d8 |
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| README.txt | ||
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