mjs: Allow null as char and void pointers in FFI

CL: mjs: Allow null as char and void pointers in FFI PUBLISHED_FROM=525a6a938eee8a7641c7af4e6996fd506f6fcfcd
cesanta · May 9, 2018 · 1c59386 · 1c59386
1 parent 9154b61
commit 1c59386
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Showing 3 changed files with 47 additions and 26 deletions.
diff --git a/mjs.c b/mjs.c
@@ -11130,26 +11130,24 @@ MJS_PRIVATE mjs_err_t mjs_ffi_call2(struct mjs *mjs) {
         break;
       case MJS_FFI_CTYPE_CHAR_PTR: {
         size_t s;
-        if (!mjs_is_string(arg)) {
+        if (mjs_is_string(arg)) {
+          /*
+           * String argument should be saved separately in order to support
+           * short strings (which are packed into mjs_val_t itself)
+           */
+          argvs[i] = arg;
+          ffi_set_ptr(&args[i], (void *) mjs_get_string(mjs, &argvs[i], &s));
+        } else if (mjs_is_null(arg)) {
+          ffi_set_ptr(&args[i], NULL);
+        } else {
           ret = MJS_TYPE_ERROR;
           mjs_prepend_errorf(
               mjs, ret, "actual arg #%d is not a string (the type idx is: %s)",
               i, mjs_typeof(arg));
           goto clean;
         }
-        /*
-         * String argument should be saved separately in order to support
-         * short strings (which are packed into mjs_val_t itself)
-         */
-        argvs[i] = arg;
-        ffi_set_ptr(&args[i], (void *) mjs_get_string(mjs, &argvs[i], &s));
       } break;
       case MJS_FFI_CTYPE_VOID_PTR:
-        if (!mjs_is_foreign(arg) && !mjs_is_string(arg)) {
-          ret = MJS_TYPE_ERROR;
-          mjs_prepend_errorf(mjs, ret, "actual arg #%d is not a ptr", i);
-          goto clean;
-        }
         if (mjs_is_string(arg)) {
           size_t n;
           /*
@@ -11158,8 +11156,14 @@ MJS_PRIVATE mjs_err_t mjs_ffi_call2(struct mjs *mjs) {
            */
           argvs[i] = arg;
           ffi_set_ptr(&args[i], (void *) mjs_get_string(mjs, &argvs[i], &n));
-        } else {
+        } else if (mjs_is_foreign(arg)) {
           ffi_set_ptr(&args[i], (void *) mjs_get_ptr(mjs, arg));
+        } else if (mjs_is_null(arg)) {
+          ffi_set_ptr(&args[i], NULL);
+        } else {
+          ret = MJS_TYPE_ERROR;
+          mjs_prepend_errorf(mjs, ret, "actual arg #%d is not a ptr", i);
+          goto clean;
         }
         break;
       case MJS_FFI_CTYPE_CALLBACK:

diff --git a/mjs/src/mjs_ffi.c b/mjs/src/mjs_ffi.c
@@ -809,26 +809,24 @@ MJS_PRIVATE mjs_err_t mjs_ffi_call2(struct mjs *mjs) {
         break;
       case MJS_FFI_CTYPE_CHAR_PTR: {
         size_t s;
-        if (!mjs_is_string(arg)) {
+        if (mjs_is_string(arg)) {
+          /*
+           * String argument should be saved separately in order to support
+           * short strings (which are packed into mjs_val_t itself)
+           */
+          argvs[i] = arg;
+          ffi_set_ptr(&args[i], (void *) mjs_get_string(mjs, &argvs[i], &s));
+        } else if (mjs_is_null(arg)) {
+          ffi_set_ptr(&args[i], NULL);
+        } else {
           ret = MJS_TYPE_ERROR;
           mjs_prepend_errorf(
               mjs, ret, "actual arg #%d is not a string (the type idx is: %s)",
               i, mjs_typeof(arg));
           goto clean;
         }
-        /*
-         * String argument should be saved separately in order to support
-         * short strings (which are packed into mjs_val_t itself)
-         */
-        argvs[i] = arg;
-        ffi_set_ptr(&args[i], (void *) mjs_get_string(mjs, &argvs[i], &s));
       } break;
       case MJS_FFI_CTYPE_VOID_PTR:
-        if (!mjs_is_foreign(arg) && !mjs_is_string(arg)) {
-          ret = MJS_TYPE_ERROR;
-          mjs_prepend_errorf(mjs, ret, "actual arg #%d is not a ptr", i);
-          goto clean;
-        }
         if (mjs_is_string(arg)) {
           size_t n;
           /*
@@ -837,8 +835,14 @@ MJS_PRIVATE mjs_err_t mjs_ffi_call2(struct mjs *mjs) {
            */
           argvs[i] = arg;
           ffi_set_ptr(&args[i], (void *) mjs_get_string(mjs, &argvs[i], &n));
-        } else {
+        } else if (mjs_is_foreign(arg)) {
           ffi_set_ptr(&args[i], (void *) mjs_get_ptr(mjs, arg));
+        } else if (mjs_is_null(arg)) {
+          ffi_set_ptr(&args[i], NULL);
+        } else {
+          ret = MJS_TYPE_ERROR;
+          mjs_prepend_errorf(mjs, ret, "actual arg #%d is not a ptr", i);
+          goto clean;
         }
         break;
       case MJS_FFI_CTYPE_CALLBACK:

diff --git a/mjs/tests/unit_test.c b/mjs/tests/unit_test.c
@@ -1176,6 +1176,11 @@ const char *test_call_ffi(struct mjs *mjs) {
   ASSERT_EQ(mjs_exec(mjs, "ffi_test_s1s('\\x00')", &res), MJS_OK);
   ASSERT_STREQ(mjs_get_cstring(mjs, &res), "");
 
+  /* null as an argument is allowed and becomes NULL;
+   * return value of NULL becomes null. */
+  ASSERT_EQ(mjs_exec(mjs, "ffi_test_s1s(null)", &res), MJS_OK);
+  ASSERT_TRUE(mjs_is_null(res));
+
   ASSERT_EXEC_OK(
       mjs_exec(mjs, "ffi('double ffi_test_d2d(double,double)')(3.71, 1.28)",
                &res));
@@ -3177,6 +3182,14 @@ const char *test_foreign_ptr(struct mjs *mjs) {
           ), &res));
   ASSERT_EQ(mjs_get_bool(mjs, res), 1);
 
+  ASSERT_EXEC_OK(mjs_exec(mjs,
+        STRINGIFY(
+          let free = ffi('void free(void *)');
+          free(null);  // null is allowed
+          true;
+          ), &res));
+  ASSERT_EQ(mjs_get_bool(mjs, res), 1);
+
   ASSERT_EXEC_OK(mjs_exec(mjs,
         STRINGIFY(
           let calloc = ffi('void *calloc(int, int)');