phpdbg_sigsafe.c

#include "phpdbg_sigsafe.h"
#include "phpdbg.h"

ZEND_EXTERN_MODULE_GLOBALS(phpdbg)

#define STR(x) #x
#define EXP_STR(x) STR(x)

static void* zend_mm_mem_alloc(zend_mm_storage *storage, size_t size, size_t alignment) {

	if (EXPECTED(size <= PHPDBG_SIGSAFE_MEM_SIZE && !PHPDBG_G(sigsafe_mem).allocated)) {
		PHPDBG_G(sigsafe_mem).allocated = 1;
		return (void *) (((size_t) PHPDBG_G(sigsafe_mem).mem & ~(alignment - 1)) + alignment);
	}

	zend_quiet_write(PHPDBG_G(io)[PHPDBG_STDERR].fd, ZEND_STRL("Tried to allocate more than " EXP_STR(PHPDBG_SIGSAFE_MEM_SIZE) " bytes from stack memory in signal handler ... bailing out of signal handler\n"));

	if (*EG(bailout)) {
		LONGJMP(*EG(bailout), FAILURE);
	}

	zend_quiet_write(PHPDBG_G(io)[PHPDBG_STDERR].fd, ZEND_STRL("Bailed out without a bailout address in signal handler!\n"));

	return NULL;
}

static void zend_mm_mem_free(zend_mm_storage *storage, void *ptr, size_t size) {
}

void phpdbg_set_sigsafe_mem(char *buffer) {
	phpdbg_signal_safe_mem *mem = &PHPDBG_G(sigsafe_mem);
	const zend_mm_handlers phpdbg_handlers = {
		zend_mm_mem_alloc,
		zend_mm_mem_free,
		NULL,
		NULL,
	};

	mem->mem = buffer;
	mem->allocated = 0;

	mem->heap = zend_mm_startup_ex(&phpdbg_handlers, NULL, 0);

	mem->old_heap = zend_mm_set_heap(mem->heap);
}

zend_mm_heap *phpdbg_original_heap_sigsafe_mem(void) {
	return PHPDBG_G(sigsafe_mem).old_heap;
}

void phpdbg_clear_sigsafe_mem(void) {
	zend_mm_set_heap(phpdbg_original_heap_sigsafe_mem());
	PHPDBG_G(sigsafe_mem).mem = NULL;
}

zend_bool phpdbg_active_sigsafe_mem(void) {
	return !!PHPDBG_G(sigsafe_mem).mem;
}