Add script function flags in the module API

src/eval.c

@@ -252,8 +252,8 @@ int evalExtractShebangFlags(sds body,
                 int numflags, jj;
                 sds *flags = sdssplitlen(parts[j], sdslen(parts[j]), ",", 1, &numflags);
                 for (jj = 0; jj < numflags; jj++) {
-                    scriptFlag *sf;
-                    for (sf = scripts_flags_def; sf->flag; sf++) {
+                    scriptFlagStr *sf;
+                    for (sf = scriptFlags; sf->flag; sf++) {
                         if (!strcmp(flags[jj], sf->str)) break;
                     }
                     if (!sf->flag) {

src/functions.c

@@ -504,15 +504,15 @@ void functionStatsCommand(client *c) {
 static void functionListReplyFlags(client *c, functionInfo *fi) {
     /* First count the number of flags we have */
     int flagcount = 0;
-    for (scriptFlag *flag = scripts_flags_def; flag->str; ++flag) {
+    for (scriptFlagStr *flag = scriptFlags; flag->str; ++flag) {
         if (fi->compiled_function->f_flags & flag->flag) {
             ++flagcount;
         }
     }
 
     addReplySetLen(c, flagcount);
 
-    for (scriptFlag *flag = scripts_flags_def; flag->str; ++flag) {
+    for (scriptFlagStr *flag = scriptFlags; flag->str; ++flag) {
         if (fi->compiled_function->f_flags & flag->flag) {
             addReplyStatus(c, flag->str);
         }

src/lua/function_lua.c

@@ -212,7 +212,7 @@ static int luaRegisterFunctionReadFlags(lua_State *lua, uint64_t *flags) {
 
         const char *flag_str = lua_tostring(lua, -1);
         int found = 0;
-        for (scriptFlag *flag = scripts_flags_def; flag->str; ++flag) {
+        for (scriptFlagStr *flag = scriptFlags; flag->str; ++flag) {
             if (!strcasecmp(flag->str, flag_str)) {
                 f_flags |= flag->flag;
                 found = 1;

src/script.c

@@ -33,12 +33,12 @@
 #include "cluster_slot_stats.h"
 #include "module.h"
 
-scriptFlag scripts_flags_def[] = {
-    {.flag = SCRIPT_FLAG_NO_WRITES, .str = "no-writes"},
-    {.flag = SCRIPT_FLAG_ALLOW_OOM, .str = "allow-oom"},
-    {.flag = SCRIPT_FLAG_ALLOW_STALE, .str = "allow-stale"},
-    {.flag = SCRIPT_FLAG_NO_CLUSTER, .str = "no-cluster"},
-    {.flag = SCRIPT_FLAG_ALLOW_CROSS_SLOT, .str = "allow-cross-slot-keys"},
+scriptFlagStr scriptFlags[] = {
+    {.flag = VMSE_SCRIPT_FLAG_NO_WRITES, .str = "no-writes"},
+    {.flag = VMSE_SCRIPT_FLAG_ALLOW_OOM, .str = "allow-oom"},
+    {.flag = VMSE_SCRIPT_FLAG_ALLOW_STALE, .str = "allow-stale"},
+    {.flag = VMSE_SCRIPT_FLAG_NO_CLUSTER, .str = "no-cluster"},
+    {.flag = VMSE_SCRIPT_FLAG_ALLOW_CROSS_SLOT, .str = "allow-cross-slot-keys"},
     {.flag = 0, .str = NULL}, /* flags array end */
 };
 

src/script.h

@@ -91,12 +91,12 @@ struct scriptRunCtx {
 #define SCRIPT_FLAG_ALLOW_CROSS_SLOT (1ULL << 5)
 
 /* Defines a script flags */
-typedef struct scriptFlag {
-    uint64_t flag;
+typedef struct scriptFlagStr {
+    ValkeyModuleScriptingEngineScriptFlag flag;
     const char *str;
-} scriptFlag;
+} scriptFlagStr;
 
-extern scriptFlag scripts_flags_def[];
+extern scriptFlagStr scriptFlags[];
 
 uint64_t scriptFlagsToCmdFlags(uint64_t cmd_flags, uint64_t script_flags);
 int scriptPrepareForRun(scriptRunCtx *r_ctx,

src/valkeymodule.h

@@ -907,6 +907,15 @@ typedef enum ValkeyModuleScriptingEngineExecutionState {
     VMSE_STATE_KILLED,
 } ValkeyModuleScriptingEngineExecutionState;
 
+typedef enum ValkeyModuleScriptingEngineScriptFlag {
+    VMSE_SCRIPT_FLAG_NO_WRITES = (1ULL << 0),
+    VMSE_SCRIPT_FLAG_ALLOW_OOM = (1ULL << 1),
+    VMSE_SCRIPT_FLAG_ALLOW_STALE = (1ULL << 2),
+    VMSE_SCRIPT_FLAG_NO_CLUSTER = (1ULL << 3),
+    VMSE_SCRIPT_FLAG_EVAL_COMPAT_MODE = (1ULL << 4), /* EVAL Script backwards compatible behavior, no shebang provided */
+    VMSE_SCRIPT_FLAG_ALLOW_CROSS_SLOT = (1ULL << 5),
+} ValkeyModuleScriptingEngineScriptFlag;
+
 typedef struct ValkeyModuleScriptingEngineCallableLazyEnvReset {
     void *context;
 

tests/modules/helloscripting.c

@@ -27,7 +27,7 @@
  * RETURN        # returns the current value on the top of the stack and marks
  *               # the end of the function declaration
  *
- * FUNCTION bar  # declaration of function 'bar'
+ * RFUNCTION bar # declaration of read-only function 'bar'
  * CONSTI 432    # pushes the value 432 to the top of the stack
  * RETURN        # returns the current value on the top of the stack and marks
  *               # the end of the function declaration.
@@ -55,6 +55,7 @@
  */
 typedef enum HelloInstKind {
     FUNCTION = 0,
+    RFUNCTION,
     CONSTI,
     CONSTS,
     ARGS,
@@ -69,6 +70,7 @@ typedef enum HelloInstKind {
  */
 const char *HelloInstKindStr[] = {
     "FUNCTION",
+    "RFUNCTION",
     "CONSTI",
     "CONSTS",
     "ARGS",
@@ -119,6 +121,7 @@ typedef struct HelloFunc {
     HelloInst instructions[256];
     uint32_t num_instructions;
     uint32_t index;
+    int read_only;
 } HelloFunc;
 
 /*
@@ -207,11 +210,12 @@ static HelloInstKind helloLangParseInstruction(const char *token) {
 /*
  * Parses the function param.
  */
-static void helloLangParseFunction(HelloFunc *func) {
+static void helloLangParseFunction(HelloFunc *func, int read_only) {
     char *token = strtok(NULL, " \n");
     ValkeyModule_Assert(token != NULL);
     func->name = ValkeyModule_Alloc(sizeof(char) * strlen(token) + 1);
     strcpy(func->name, token);
+    func->read_only = read_only;
 }
 
 /*
@@ -283,12 +287,13 @@ static int helloLangParseCode(const char *code,
 
         switch (kind) {
         case FUNCTION:
+        case RFUNCTION:
             ValkeyModule_Assert(currentFunc == NULL);
             currentFunc = ValkeyModule_Alloc(sizeof(HelloFunc));
             memset(currentFunc, 0, sizeof(HelloFunc));
             currentFunc->index = program->num_functions;
             program->functions[program->num_functions++] = currentFunc;
-            helloLangParseFunction(currentFunc);
+            helloLangParseFunction(currentFunc, kind == RFUNCTION);
             break;
         case CONSTI:
             ValkeyModule_Assert(currentFunc != NULL);
@@ -424,6 +429,7 @@ static void helloDebuggerLogCurrentInstr(uint32_t pc, HelloInst *instr) {
         msg = ValkeyModule_CreateStringPrintf(NULL, ">>> %3u: %s", pc, HelloInstKindStr[instr->kind]);
         break;
     case FUNCTION:
+    case RFUNCTION:
     case _NUM_INSTRUCTIONS:
         ValkeyModule_Assert(0);
     }
@@ -528,6 +534,7 @@ static HelloExecutionState executeHelloLangFunction(ValkeyModuleCtx *module_ctx,
             return FINISHED;
 	    }
         case FUNCTION:
+        case RFUNCTION:
         case _NUM_INSTRUCTIONS:
             ValkeyModule_Assert(0);
         }
@@ -646,7 +653,7 @@ static ValkeyModuleScriptingEngineCompiledFunction **createHelloLangEngine(Valke
             .name = ValkeyModule_CreateString(NULL, func->name, strlen(func->name)),
             .function = func,
             .desc = NULL,
-            .f_flags = 0,
+            .f_flags = func->read_only ? VMSE_SCRIPT_FLAG_NO_WRITES : 0,
         };
 
         compiled_functions[i] = cfunc;

tests/unit/moduleapi/scriptingengine.tcl

@@ -1,6 +1,6 @@
 set testmodule [file normalize tests/modules/helloscripting.so]
 
-set HELLO_PROGRAM "#!hello name=mylib\nFUNCTION foo\nARGS 0\nRETURN\nFUNCTION bar\nCONSTI 432\nRETURN"
+set HELLO_PROGRAM "#!hello name=mylib\nRFUNCTION foo\nARGS 0\nRETURN\nFUNCTION bar\nCONSTI 432\nRETURN"
 
 start_server {tags {"modules"}} {
     r module load $testmodule
@@ -197,6 +197,16 @@ start_server {tags {"modules"}} {
                 RETURN
             } 0
         }
+
+        r function load {#!hello name=errlib
+                RFUNCTION callcmd
+                CONSTS x
+                CONSTI 43
+                CONSTI 2
+                CALL SET
+                RETURN
+            }
+        assert_error {ERR Write commands are not allowed*} {r fcall callcmd 0}
     }
 
     test {Call server command when OOM} {
@@ -301,6 +311,7 @@ start_server {tags {"modules"}} {
     }
 
     test {List scripting engine functions} {
+        r function flush sync
         r function load replace "#!hello name=mylib\nFUNCTION foobar\nARGS 0\nRETURN"
         r function list
     } {{library_name mylib engine HELLO functions {{name foobar description {} flags {}}}}}