Some relative module imports fail in preload with Module "(path)" not found!

[cmidgley]

Build environment: Windows
Moddable SDK version: Latest released
Target device: Win, ESP32

Description
Another path resolution issue similar to #1372, but this time with preload. It appears that preload is unable to resolve some relative module loads using the private-scope style (root/#module/...). I've found that it works with ..\myfile.js but not ..\..\myfile.js, such as "import { xyz } from "../../myfile.js";" where it reports Module "../../myfile.js" not found!.

See this repo for a small demo of the problem. If you remove the preload, the module runs fine, but with the preload the build fails with:

ReferenceError: module "../../root.js" not found
### ReferenceError: module "../../root.js" not found!
NMAKE : fatal error U1077: 'xsl args.txt ' : return code '0xd'
Stop.

Steps to Reproduce

1. Clone this repo
2. Build with mcconfig -m -d and see the preload failure
3. Remove the preload from manifest.json
4. Build again, and see the module runs fine

[phoddie]

The XS linker (xsl) performs the preload operation. It didn't implement support for module specifiers containing ../../specifier. This hasn't generally been an issue because module specifiers in XS are not usually paths. It comes up when preloading modules from Node packages in XS.

We've got a fix for that which works for your test case. The changes will be in the next repository update. If you want to try them sooner, here's the updated fxFindModule function.

source code

txID fxFindModule(txMachine* the, txSlot* realm, txID moduleID, txSlot* slot)
{
	txLinker* linker = (txLinker*)(the->context);
	char name[C_PATH_MAX];
	char buffer[C_PATH_MAX];
	char separator;
	txInteger dot = 0;
	txInteger i = 0;
	txInteger hash = 0;
	txString slash;
	txString path;
	txID id;
		
	fxToStringBuffer(the, slot, name, sizeof(name) - 4);
	if (name[0] == '.') {
		if (name[1] == '/') {
			dot = 1;
			i = 1;
		}
		else if ((name[1] == '.') && (name[2] == '/')) {
			dot = 2;
			i = 2;
			while ((name[i + 1] == '.') && (name[i + 2] == '.') && (name[i + 3] == '/')) {
				dot++;
				i += 3;
			}
		}
	}
	else if (name[0] == '#') {
		hash = 1;
	}
	else if (c_strncmp(name, "moddable:", 9) == 0)
		c_memmove(name, name + 9, c_strlen(name) - 8);
	
	separator = linker->base[0];
	fxSlashPath(name, '/', separator);
	slash = c_strrchr(name, separator);
	if (!slash)
		slash = name;
	slash = c_strrchr(slash, '.');
	if (slash && (!c_strcmp(slash, ".js") || !c_strcmp(slash, ".mjs") || !c_strcmp(slash, ".xsb")))
		*slash = 0;
		
	if (dot > 0) {
		if (moduleID == XS_NO_ID)
			return XS_NO_ID;
		buffer[0] = separator;
		path = buffer + 1;
		c_strcpy(path, fxGetKeyName(the, moduleID));
		slash = c_strrchr(buffer, separator);
		if (!slash)
			return XS_NO_ID;
		*slash = 0;
		dot--;
		while (dot > 0) {
			slash = c_strrchr(buffer, separator);
			if (!slash)
				return XS_NO_ID;
			*slash = 0;
			dot--;
		}
		if ((c_strlen(buffer) + c_strlen(name + i)) >= sizeof(buffer))
			mxRangeError("path too long");
		c_strcat(buffer, name + i);
	}
	else if (hash) {
		if (moduleID == XS_NO_ID)
			return XS_NO_ID;
		path = buffer;
		c_strcpy(path, fxGetKeyName(the, moduleID));
		slash = c_strchr(buffer, separator);
		if (!slash)
			return XS_NO_ID;
		if (path[0] == '@') {
			slash = c_strchr(slash + 1, mxSeparator);
			if (!slash)
				return XS_NO_ID;
		}
		*(slash + 1) = 0;
		if ((c_strlen(buffer) + c_strlen(name)) >= sizeof(buffer))
			mxRangeError("path too long");
		c_strcat(buffer, name);
	}
	else
		path = name;
		
	if (fxFindScript(the, path, &id))
		return id;
	return XS_NO_ID;
}

Note: the example's manifest preloads "root/main". That causes "root/#another" to be preloaded too, so it executes the traces at link time (you will see them as part of the build output). To make the test do something meaningful at runtime, preload "root/#another" instead.

[cmidgley]

All my private modules preload - totally awesome. Thanks!