[Tinycc-devel] Fix boundschecking for signal/sigaction/fork

[Herman ten Brugge]

    Hello,
    
    I have recently added code to redirect fork/sigaction to the bound
    checking
    code. I also implemented limited thread local storage support.
    
    See also commit Fix
        boundschecking for signal/sigaction/fork
    
    The radare2 project (https://github.com/radareorg/radare2) has very
    high
    load for fork/sigaction and bound checking failed.
    For bound checking and tcc to work I had to do patches and sent them
    to a
    maintainer for the radare2 project. The patches I sent probably need
    some
    review and are not present in the radare2 git repository yet.
    After the above commit and the changes to radare2 project to compile
    with "tcc -b" the result was the same as compiled with gcc.
    
    The implementation of thread local storage is just enough to link
    the
    gcc compiled code of bcheck.c on i386/x86_64. It does not mean that
    thread local storage is now supported and static linking still
    fails.
    
    There is still one problem. fork() is not compatible with -run and
    SELINUX.
    You can see this when doing:
    tcc -b -run tests/tests2/114_bound_signal.c
    
    The problem is that MAP_SHARED is used. This means the parent and
    child
    still share the same memory after fork().
    The patch below fixes this.
    Can I apply this patch or is there a better solution?
    
            Herman
    
    
    diff --git a/tccrun.c b/tccrun.c
    index 17f1eeb..7057e44 100644
    --- a/tccrun.c
    +++ b/tccrun.c
    @@ -88,8 +88,12 @@ LIBTCCAPI int tcc_relocate(TCCState *s1, void
    *ptr)
         unlink(tmpfname);
         ftruncate(fd, size);
     
    +#if 0 /* does not work with fork */
         ptr = mmap (NULL, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd,
    0);
         prx = mmap (NULL, size, PROT_READ|PROT_EXEC, MAP_SHARED, fd,
    0);
    +#else
    +    ptr = prx = mmap (NULL, size, PROT_READ|PROT_WRITE|PROT_EXEC,
    MAP_PRIVATE, fd, 0);
    +#endif
         if (ptr == MAP_FAILED || prx == MAP_FAILED)
            tcc_error("tccrun: could not map memory");
         dynarray_add(&s1->runtime_mem,
    &s1->nb_runtime_mem, (void*)(addr_t)size);
    diff --git a/tests/tests2/Makefile b/tests/tests2/Makefile
    index f7f4791..93e4062 100644
    --- a/tests/tests2/Makefile
    +++ b/tests/tests2/Makefile
    @@ -94,7 +94,6 @@ GEN-ALWAYS =
         ./a.exe
     
     114_bound_signal.test: FLAGS += -b
    -114_bound_signal.test: NORUN = true # tcc -run does not support
    fork and -b and SELINUX
     115_bound_setjmp.test: FLAGS += -b
     116_bound_setjmp2.test: FLAGS += -b
     117_builtins.test: T1 = ( $(TCC) -run $1 && $(TCC) -b -run
    $1 )