Merge #1688

1688: Fix sentinel value in wasm_limits_t for memory in wasm_c_api r=MarkMcCaskey a=MarkMcCaskey

FIxes issue mentioned in #1631 (comment)


Co-authored-by: Mark McCaskey <mark@wasmer.io>

lib/c-api/src/wasm_c_api/types/memory.rs

@@ -33,8 +33,8 @@ pub struct wasm_limits_t {
 #[no_mangle]
 pub unsafe extern "C" fn wasm_memorytype_new(limits: &wasm_limits_t) -> Box<wasm_memorytype_t> {
     let min_pages = Pages(limits.min as _);
-    // TODO: investigate if `0` is in fact a sentinel value here
-    let max_pages = if limits.max == 0 {
+    // u32::max_value() is a sentinel value for no max specified
+    let max_pages = if limits.max == u32::max_value() {
         None
     } else {
         Some(Pages(limits.max as _))

lib/c-api/tests/wasm_c_api/test-memory.c

@@ -21,20 +21,22 @@ int main(int argc, const char *argv[]) {
   own wasm_engine_t* engine = wasm_engine_new();
   own wasm_store_t* store = wasm_store_new(engine);
 
+  // =====================
   wasm_limits_t limits1 = {
     .min = 0,
-    .max = wasm_limits_max_default,
+    .max = 0x7FFFFFFF,
   };
   own wasm_memorytype_t* memtype1 = wasm_memorytype_new(&limits1);
   own wasm_memory_t* memory1 = wasm_memory_new(store, memtype1);
   assert(memory1 == NULL);
   char* error = get_wasmer_error();
   printf("Found error string: %s\n", error);
-  assert(0 == strcmp("The maximum requested memory (4294967295 pages) is greater than the maximum allowed memory (65536 pages)", error));
+  assert(0 == strcmp("The maximum requested memory (2147483647 pages) is greater than the maximum allowed memory (65536 pages)", error));
   free(error);
 
   wasm_memorytype_delete(memtype1);
 
+  // =====================
   wasm_limits_t limits2 = {
     .min = 15,
     .max = 25,
@@ -46,6 +48,20 @@ int main(int argc, const char *argv[]) {
   wasm_memorytype_delete(memtype2);
   wasm_memory_delete(memory2);
 
+  // =====================
+  wasm_limits_t limits3 = {
+    .min = 15,
+    .max = wasm_limits_max_default,
+  };
+  own wasm_memorytype_t* memtype3 = wasm_memorytype_new(&limits3);
+  own wasm_memory_t* memory3 = wasm_memory_new(store, memtype3);
+  assert(memory3 != NULL);
+  int size = wasm_memory_size(memory3);
+  printf("memory size: %d\n", size);
+
+  wasm_memorytype_delete(memtype3);
+  wasm_memory_delete(memory3);
+
   printf("Shutting down...\n");
   wasm_store_delete(store);
   wasm_engine_delete(engine);