Bug 1232067 - Ensure the libc free() is used if the a.out free() is not available. r=yoric

--HG--
extra : rebase_source : 9545ddec5807d63fc2a002480db02c81f2324a72

toolkit/components/osfile/modules/osfile_shared_allthreads.jsm

@@ -1050,6 +1050,42 @@ Library.prototype = Object.freeze({
     });
   },
 
+  /**
+   * Define a js-ctypes function lazily using ctypes method declare,
+   * with a fallback library to use if this library can't be opened
+   * or the function cannot be declared.
+   *
+   * @param {fallbacklibrary} The fallback Library object.
+   * @param {object} The object containing the function as a field.
+   * @param {string} The name of the field containing the function.
+   * @param {string} symbol The name of the function, as defined in the
+   * library.
+   * @param {ctypes.abi} abi The abi to use, or |null| for default.
+   * @param {ctypes.CType} returnType The type of values returned by the function.
+   * @param {...ctypes.CType} argTypes The type of arguments to the function.
+   */
+  declareLazyWithFallback: function(fallbacklibrary, object, field, ...args) {
+    let lib = this;
+    Object.defineProperty(object, field, {
+      get: function() {
+        delete this[field];
+        try {
+          let ffi = lib.library.declare(...args);
+          if (ffi) {
+            return this[field] = ffi;
+          }
+        } catch (ex) {
+          // Use the fallback library and get the symbol from there.
+          fallbacklibrary.declareLazy(object, field, ...args);
+          return object[field];
+        }
+        return undefined;
+      },
+      configurable: true,
+      enumerable: true
+    });
+  },
+
   toString: function() {
     return "[Library " + this.name + "]";
   }

toolkit/components/osfile/modules/osfile_unix_back.jsm

@@ -264,25 +264,17 @@
          // We override the definition of free() on several platforms.
          let default_lib = new SharedAll.Library("default_lib",
                                                  "a.out");
-         try {
+
          // On platforms for which we override free(), nspr defines
          // a special library name "a.out" that will resolve to the
          // correct implementation free().
+         // If it turns out we don't have an a.out library or a.out
+         // doesn't contain free, use the ordinary libc free.
 
-           default_lib.declareLazy(SysFile, "free",
+         default_lib.declareLazyWithFallback(libc, SysFile, "free",
            "free", ctypes.default_abi,
            /*return*/ ctypes.void_t,
            /*ptr*/    ctypes.voidptr_t);
-
-         } catch (ex) {
-           // We don't have an a.out library or a.out doesn't contain free.
-           // Either way, use the ordinary libc free.
-
-           libc.declareLazy(SysFile, "free",
-             "free", ctypes.default_abi,
-             /*return*/ ctypes.void_t,
-             /*ptr*/    ctypes.voidptr_t);
-         }
        }