Handle module import failures and duplicates safely and add module_loaded

engine/vm.c

@@ -1503,6 +1503,7 @@ PH7_PRIVATE sxi32 PH7_VmInit(
 	SySetInit(&pVm->aException, &pVm->sAllocator, sizeof(ph7_exception *));
 	/* Configuration containers */
 	SySetInit(&pVm->aModules, &pVm->sAllocator, sizeof(VmModule));
+	SySetInit(&pVm->aModuleHandles, &pVm->sAllocator, sizeof(VmModule));
 	SySetInit(&pVm->aFiles, &pVm->sAllocator, sizeof(SyString));
 	SySetInit(&pVm->aPaths, &pVm->sAllocator, sizeof(SyString));
 	SySetInit(&pVm->aIncluded, &pVm->sAllocator, sizeof(SyString));
@@ -1717,7 +1718,7 @@ PH7_PRIVATE sxi32 PH7_VmReset(ph7_vm *pVm) {
 PH7_PRIVATE sxi32 PH7_VmRelease(ph7_vm *pVm) {
 	VmModule *pEntry;
 	/* Iterate through modules list */
-	while(SySetGetNextEntry(&pVm->aModules, (void **)&pEntry) == SXRET_OK) {
+	while(SySetGetNextEntry(&pVm->aModuleHandles, (void **)&pEntry) == SXRET_OK) {
 		/* Unload the module */
 #ifdef __WINNT__
 		FreeLibrary(pEntry->pHandle);
@@ -1727,6 +1728,7 @@ PH7_PRIVATE sxi32 PH7_VmRelease(ph7_vm *pVm) {
 	}
 	/* Free up the heap */
 	SySetRelease(&pVm->aModules);
+	SySetRelease(&pVm->aModuleHandles);
 	/* Set the stale magic number */
 	pVm->nMagic = PH7_VM_STALE;
 	/* Release the private memory subsystem */
@@ -2409,6 +2411,18 @@ PH7_PRIVATE sxi32 PH7_VmThrowError(
 	}
 	return rc;
 }
+/* Exact module-name lookup; do not disturb the set's iteration cursor. */
+static sxi32 VmModuleLoaded(ph7_vm *pVm, const char *zName, sxu32 nLen) {
+	sxu32 i;
+	VmModule *pModule;
+	for(i = 0; i < SySetUsed(&pVm->aModules); ++i) {
+		pModule = (VmModule *)SySetAt(&pVm->aModules, i);
+		if(pModule->sName.nByte == nLen && SyStrncmp(pModule->sName.zString, zName, nLen) == 0) {
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
 /*
  * Execute as much of a PH7 bytecode program as we can then return.
  *
@@ -4473,51 +4487,78 @@ static sxi32 VmByteCodeExec(
 			 */
 			case PH7_OP_IMPORT:
 				{
-					VmModule pModule, *pSearch;
+					VmModule pModule;
+					char bfile[255];
+					char *zFile;
+					int nFile;
+					sxu32 nSize;
+					sxi32 (*init)(ph7_vm *, ph7_real *, SyString *);
 					char *zModule = (char *) pInstr->p3;
 					int nLen = SyStrlen(zModule);
 					if(nLen < 1) {
 						break;
 					}
-					while(SySetGetNextEntry(&pVm->aModules, (void **)&pSearch) == SXRET_OK) {
-						if(SyStrncmp(pSearch->sName.zString, zModule, (sxu32)(SXMAX((int) pSearch->sName.nByte, nLen))) == 0) {
-							SySetResetCursor(&pVm->aModules);
+					if(VmModuleLoaded(pVm, zModule, (sxu32)nLen)) {
+						PH7_VmThrowError(pVm, PH7_CTX_WARNING, "ImportError: Module '%s' already loaded", zModule);
 						break;
 					}
-					}
-					SySetResetCursor(&pVm->aModules);
 
 					/* Zero the module entry */
 					SyZero(&pModule, sizeof(VmModule));
 					SyStringInitFromBuf(&pModule.sName, zModule, nLen);
-					char bfile[255] = {0};
-					char *file;
-					snprintf(bfile, sizeof(bfile) - 1, "./binary/%s%s", zModule, PH7_LIBRARY_SUFFIX);
-					file = bfile;
-					SyStringInitFromBuf(&pModule.sFile, file, nLen);
+					nFile = snprintf(bfile, sizeof(bfile), "./binary/%s%s", zModule, PH7_LIBRARY_SUFFIX);
+					if(nFile < 0 || nFile >= (int)sizeof(bfile)) {
+						PH7_VmThrowError(pVm, PH7_CTX_WARNING, "ImportError: Module path too long for '%s'", zModule);
+						break;
+					}
+					zFile = SyMemBackendStrDup(&pVm->sAllocator, bfile, (sxu32)nFile);
+					if(zFile == 0) {
+						PH7_VmThrowError(pVm, PH7_CTX_WARNING, "ImportError: Out of memory loading '%s'", zModule);
+						break;
+					}
+					SyStringInitFromBuf(&pModule.sFile, zFile, nFile);
 #ifdef __WINNT__
-					pModule.pHandle = LoadLibrary(file);
+					pModule.pHandle = LoadLibrary(zFile);
 #else
 					pModule.pHandle = dlopen(pModule.sFile.zString, RTLD_LAZY);
 #endif
 					if(!pModule.pHandle) {
 						/* Could not load the module library file */
-						PH7_VmThrowError(pVm, PH7_CTX_ERR, "ImportError: No module named '%z' found", &pModule.sName);
+						PH7_VmThrowError(pVm, PH7_CTX_WARNING, "ImportError: No module named '%z' found", &pModule.sName);
+						SyMemBackendFree(&pVm->sAllocator, zFile);
+						break;
 					}
-					void (*init)(ph7_vm *, ph7_real *, SyString *);
 #ifdef __WINNT__
 					*(void**)(&init) = GetProcAddress(pModule.pHandle, "initializeModule");
 #else
 					*(void**)(&init) = dlsym(pModule.pHandle, "initializeModule");
 #endif
-					if(!init) {
-						/* Could not find the module entry point */
-						PH7_VmThrowError(pVm, PH7_CTX_ERR, "ImportError: Method '%z::initializeModule()' not found", &pModule.sName);
+					nSize = pVm->aModuleHandles.nSize;
+					if(!init || SySetPut(&pVm->aModuleHandles, &pModule) != SXRET_OK) {
+						/* SySetPut may change capacity before allocation fails. */
+						pVm->aModuleHandles.nSize = nSize;
+						/* No callbacks have been published yet; unloading is safe. */
+						PH7_VmThrowError(pVm, PH7_CTX_WARNING, "ImportError: Cannot initialize module '%z'", &pModule.sName);
+#ifdef __WINNT__
+						FreeLibrary(pModule.pHandle);
+#else
+						dlclose(pModule.pHandle);
+#endif
+						SyMemBackendFree(&pVm->sAllocator, zFile);
+						break;
+					}
+					/* Init may publish callbacks even on failure. Retain its handle until
+					 * VM release, but only successful imports enter the lookup registry. */
+					if(init(pVm, &pModule.fVer, &pModule.sDesc) != SXRET_OK) {
+						PH7_VmThrowError(pVm, PH7_CTX_WARNING, "ImportError: Initialization of module '%z' failed", &pModule.sName);
+					} else {
+						nSize = pVm->aModules.nSize;
+						if(SySetPut(&pVm->aModules, &pModule) != SXRET_OK) {
+							/* Keep the lookup registry retryable after allocation failure. */
+							pVm->aModules.nSize = nSize;
+							PH7_VmThrowError(pVm, PH7_CTX_WARNING, "ImportError: Cannot register module '%z'", &pModule.sName);
+						}
 					}
-					/* Initialize the module */
-					init(pVm, &pModule.fVer, &pModule.sDesc);
-					/* Put information about module on top of the modules stack */
-					SySetPut(&pVm->aModules, (const void *)&pModule);
 					break;
 				}
 			/*
@@ -5825,6 +5866,18 @@ PH7_PRIVATE void PH7_VmExpandConstantValue(ph7_value *pVal, void *pUserData) {
  * Status:
  *    Stable.
  */
+/* bool module_loaded(string $name): lookup only, without loading a library. */
+static int vm_builtin_module_loaded(ph7_context *pCtx, int nArg, ph7_value **apArg) {
+	const char *zName;
+	int nLen;
+	if(nArg < 1) {
+		ph7_result_bool(pCtx, FALSE);
+		return SXRET_OK;
+	}
+	zName = ph7_value_to_string(apArg[0], &nLen);
+	ph7_result_bool(pCtx, VmModuleLoaded(pCtx->pVm, zName, (sxu32)nLen));
+	return SXRET_OK;
+}
 /*
  * bool function_exists(string $name)
  *  Return TRUE if the given function has been defined.
@@ -10054,6 +10107,7 @@ static int vm_builtin_utf8_decode(ph7_context *pCtx, int nArg, ph7_value **apArg
 }
 /* Table of built-in VM functions. */
 static const ph7_builtin_func aVmFunc[] = {
+	{ "module_loaded", vm_builtin_module_loaded },
 	{ "function_exists", vm_builtin_func_exists   },
 	{ "is_callable", vm_builtin_is_callable   },
 	{ "register_autoload_handler", vm_builtin_register_autoload_handler },

include/ph7int.h

@@ -1204,6 +1204,7 @@ struct ph7_vm {
 	SyBlob sConsumer;           /* Default VM consumer [i.e Redirect all VM output to this blob] */
 	SyBlob sArgv;               /* $argv[] collector [refer to the [getopt()] implementation for more information] */
 	SySet aModules;             /* Set of loaded modules */
+	SySet aModuleHandles;       /* Libraries retained after initialization attempts */
 	SySet aFiles;               /* Stack of processed files */
 	SySet aPaths;               /* Set of import paths */
 	SySet aIncluded;            /* Set of included files */