[query] add UC_QUERY_PAGE_SIZE uc_query helper

Return the current page size used by the current arch.
Useful to call uc_mem_map() with memory/size aligned.

Signed-off-by: Nicolas PLANEL <nplanel@redhat.com>

include/unicorn/unicorn.h

@@ -262,6 +262,7 @@ typedef struct uc_mem_region {
 typedef enum uc_query_type {
     // Dynamically query current hardware mode.
     UC_QUERY_MODE = 1,
+    UC_QUERY_PAGE_SIZE,
 } uc_query_type;
 
 /*

tests/unit/test_mem_map.c

@@ -158,6 +158,15 @@ static void test_strange_map(void **state)
     uc_mem_unmap(uc, 0x0,0x1000); 
 }
 
+static void test_query_page_size(void **state)
+{
+    uc_engine *uc = *state;
+
+    size_t page_size;
+    uc_assert_success(uc_query(uc, UC_QUERY_PAGE_SIZE, &page_size));
+    assert_int_equal(4096, page_size);
+}
+
 void write(uc_engine* uc, uint64_t addr, uint64_t len){
   uint8_t* buff = alloca(len);
   memset(buff,0,len);
@@ -220,6 +229,7 @@ int main(void) {
         test(test_unmap_double_map),
         test(test_overlap_unmap_double_map),
         test(test_strange_map),
+        test(test_query_page_size),
     };
 #undef test
     return cmocka_run_group_tests(tests, NULL, NULL);

uc.c

@@ -1094,6 +1094,11 @@ uint32_t uc_mem_regions(uc_engine *uc, uc_mem_region **regions, uint32_t *count)
 UNICORN_EXPORT
 uc_err uc_query(uc_engine *uc, uc_query_type type, size_t *result)
 {
+    if (type == UC_QUERY_PAGE_SIZE) {
+        *result = uc->target_page_size;
+        return UC_ERR_OK;
+    }
+    
     switch(uc->arch) {
         case UC_ARCH_ARM:
             return uc->query(uc, type, result);