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@ -45,10 +45,10 @@ extern "C" {
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* Define macros for handling SIGFPE.
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* Lee Busby, LLNL, November, 1996
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* busby1@llnl.gov
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*
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*
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*********************************************
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* Overview of the system for handling SIGFPE:
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*
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*
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* This file (Include/pyfpe.h) defines a couple of "wrapper" macros for
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* insertion into your Python C code of choice. Their proper use is
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* discussed below. The file Python/pyfpe.c defines a pair of global
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@ -59,33 +59,33 @@ extern "C" {
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* named fpectl. This module is standard in every respect. It can be loaded
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* either statically or dynamically as you choose, and like any other
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* Python module, has no effect until you import it.
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*
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*
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* In the general case, there are three steps toward handling SIGFPE in any
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* Python code:
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*
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*
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* 1) Add the *_PROTECT macros to your C code as required to protect
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* dangerous floating point sections.
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*
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*
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* 2) Turn on the inclusion of the code by adding the ``--with-fpectl''
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* flag at the time you run configure. If the fpectl or other modules
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* which use the *_PROTECT macros are to be dynamically loaded, be
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* sure they are compiled with WANT_SIGFPE_HANDLER defined.
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*
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*
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* 3) When python is built and running, import fpectl, and execute
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* fpectl.turnon_sigfpe(). This sets up the signal handler and enables
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* generation of SIGFPE whenever an exception occurs. From this point
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* on, any properly trapped SIGFPE should result in the Python
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* FloatingPointError exception.
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*
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*
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* Step 1 has been done already for the Python kernel code, and should be
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* done soon for the NumPy array package. Step 2 is usually done once at
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* python install time. Python's behavior with respect to SIGFPE is not
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* changed unless you also do step 3. Thus you can control this new
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* facility at compile time, or run time, or both.
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*
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********************************
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*
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********************************
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* Using the macros in your code:
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*
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*
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* static PyObject *foobar(PyObject *self,PyObject *args)
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* {
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* ....
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@ -94,17 +94,17 @@ extern "C" {
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* PyFPE_END_PROTECT(result)
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* ....
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* }
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*
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*
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* If a floating point error occurs in dangerous_op, foobar returns 0 (NULL),
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* after setting the associated value of the FloatingPointError exception to
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* "Error in foobar". ``Dangerous_op'' can be a single operation, or a block
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* of code, function calls, or any combination, so long as no alternate
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* return is possible before the PyFPE_END_PROTECT macro is reached.
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*
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*
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* The macros can only be used in a function context where an error return
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* can be recognized as signaling a Python exception. (Generally, most
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* functions that return a PyObject * will qualify.)
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*
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*
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* Guido's original design suggestion for PyFPE_START_PROTECT and
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* PyFPE_END_PROTECT had them open and close a local block, with a locally
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* defined jmp_buf and jmp_buf pointer. This would allow recursive nesting
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@ -112,17 +112,17 @@ extern "C" {
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* variables need to be declared with the "volatile" type qualifier to keep
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* setjmp from corrupting their values. Some current implementations seem
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* to be more restrictive. For example, the HPUX man page for setjmp says
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*
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*
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* Upon the return from a setjmp() call caused by a longjmp(), the
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* values of any non-static local variables belonging to the routine
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* from which setjmp() was called are undefined. Code which depends on
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* such values is not guaranteed to be portable.
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*
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*
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* I therefore decided on a more limited form of nesting, using a counter
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* variable (PyFPE_counter) to keep track of any recursion. If an exception
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* occurs in an ``inner'' pair of macros, the return will apparently
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* come from the outermost level.
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*
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*
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*/
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#ifdef WANT_SIGFPE_HANDLER
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@ -146,14 +146,14 @@ if (!PyFPE_counter++ && setjmp(PyFPE_jbuf)) { \
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* this statement so that it gets executed *before* the unsafe expression
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* which we're trying to protect. That pretty well messes things up,
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* of course.
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*
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*
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* If the expression(s) you're trying to protect don't happen to return a
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* value, you will need to manufacture a dummy result just to preserve the
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* correct ordering of statements. Note that the macro passes the address
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* of its argument (so you need to give it something which is addressable).
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* If your expression returns multiple results, pass the last such result
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* to PyFPE_END_PROTECT.
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*
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*
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* Note that PyFPE_dummy returns a double, which is cast to int.
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* This seeming insanity is to tickle the Floating Point Unit (FPU).
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* If an exception has occurred in a preceding floating point operation,
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