perfectly accurate fs

turns out, file cost is 0 for loot disks, so there was never an actual
discrepancy

src/main.c

@@ -330,7 +330,7 @@ int main(int argc, char **argv) {
 	bool sandboxMem = getenv("NN_MEMSAND") != NULL;
 	bool showStats = getenv("NN_STAT") != NULL;
 
-	const char *mainDir = "OpenOS";
+	const char *mainDir = "openos";
 	if(argc > 1) mainDir = argv[1];
 
 	nn_Context ctx;
@@ -378,12 +378,9 @@ int main(int argc, char **argv) {
 		.isReadonly = false,
 	};
 
-	printf("%zu bytes logically used by OpenOS\n", ncl_spaceUsedIn(ncl_defaultFS, "data/OpenOS"));
-	printf("%zu bytes physically used by OpenOS\n", ncl_spaceUsedBy(ncl_defaultFS, "data/OpenOS"));
-
 	nn_Component *eepromCard = nn_createVEEPROM(u, "eeprom", &veeprom, &nn_defaultEEPROMs[3]);
 
-	nn_Component *managedfs = ncl_createFilesystem(u, "mainFS", "data/OpenOS", &nn_defaultFilesystems[3], true);
+	nn_Component *managedfs = ncl_createFilesystem(u, "mainFS", "data/openos", &nn_defaultFilesystems[3], true);
 
 	size_t ramTotal = 0;
 	ramTotal += nn_ramSizes[5];

src/ncomplib.c

@@ -115,7 +115,18 @@ ncl_VFS ncl_defaultFS = (ncl_VFS) {
 #else
 	.pathsep = '/',
 #endif
-	.fileCost = 512,
+	.fileCost = NCL_FILECOST_DEFAULT,
+};
+
+ncl_VFS ncl_installerFS = (ncl_VFS) {
+	.state = NULL,
+	.handler = ncl_defaultHandler,
+#ifdef NN_WINDOWS
+	.pathsep = '\\',
+#else
+	.pathsep = '/',
+#endif
+	.fileCost = NCL_FILECOST_INSTALL,
 };
 
 void *ncl_openfile(ncl_VFS vfs, const char *path, const char *mode) {
@@ -213,8 +224,8 @@ bool ncl_readdir(ncl_VFS vfs, void *dir, char name[NN_MAX_PATH]) {
 size_t ncl_spaceUsedIn(ncl_VFS vfs, const char *path) {
 	ncl_Stat s;
 	if(!ncl_stat(vfs, path, &s)) return 0;
-	if(!s.isDirectory) return vfs.fileCost + s.size;
-	size_t spaceUsed = vfs.fileCost;
+	size_t spaceUsed = vfs.fileCost + s.size;
+	if(!s.isDirectory) return spaceUsed;
 	void *dir = ncl_opendir(vfs, path);
 	if(dir == NULL) return spaceUsed;
 	char name[NN_MAX_PATH];
@@ -289,7 +300,7 @@ bool ncl_mkdirRecursive(ncl_VFS vfs, const char *path) {
 	char buf[NN_MAX_PATH];
 	// use snprintf instead of strncpy cuz NULL terminator
 	snprintf(buf, NN_MAX_PATH, "%s", path);
-	char *sep = strrchr(buf, '/');
+	char *sep = strrchr(buf, vfs.pathsep);
 	if(sep == NULL) {
 		return ncl_mkdir(vfs, path);
 	}
@@ -606,6 +617,12 @@ static nn_Exit ncl_fsHandler(nn_FSRequest *req) {
 		}
 		char path[NN_MAX_PATH];
 		ncl_fixPath(state, req->open.path, path);
+		size_t spaceRemaining = state->conf.spaceTotal - ncl_fsGetUsage(state);
+		if(mode[0] == 'w' && !ncl_exists(state->vfs, path) && spaceRemaining < state->vfs.fileCost) {
+			nn_unlock(ctx, state->lock);
+			nn_setError(C, "out of space");
+			return NN_EBADCALL;
+		}
 		void *file = ncl_openfile(state->vfs, path, mode);
 		if(file == NULL) {
 			nn_unlock(ctx, state->lock);

src/ncomplib.h

@@ -9,6 +9,17 @@
 #define NCL_GPU "ncl-gpu"
 #define NCL_SCREEN "ncl-screen"
 
+// Default file cost.
+// This is for a normal HDD/floppy.
+#define NCL_FILECOST_DEFAULT 512
+
+// File cost on an installer floppy.
+// In OC, those are backed by a file called ZipFileInputStream.
+// That class has a different implementation for spaceUsed,
+// it is almost identical except it does not add the file cost.
+// For that reason, it is recommended to set it to 0, for parity.
+#define NCL_FILECOST_INSTALL 0
+
 #define NCL_MAX_VRAMBUF 128
 #define NCL_MAX_KEYBOARD 64
 
@@ -124,8 +135,22 @@ typedef struct ncl_VFS {
 	size_t fileCost;
 } ncl_VFS;
 
+// The default FS.
+// Uses a basic implementation using POSIX/Windows FS APIs,
+// or erroring on all operations if baremetal.
+// Has default file cost (512)
 extern ncl_VFS ncl_defaultFS;
 
+// The installer FS.
+// Same implementation as the default FS,
+// but has a file cost of 0.
+// This makes it accurate to ZipFileInputStreams in OC,
+// which are used for the loot floppy disks.
+// ENSURE ALL FILESYSTEMS WITH 0 FILE COST
+// ARE READ-ONLY, OR ELSE YOU CAN BE SPAMMED
+// ENDLESSLY WITH GIGABYTES OF DISK HOGGING.
+extern ncl_VFS ncl_installerFS;
+
 void *ncl_openfile(ncl_VFS vfs, const char *path, const char *mode);
 void ncl_closefile(ncl_VFS vfs, void *file);
 // returns false on EoF