handle mnemonic customization better. issue capstone-engine#1514

cs.c

@@ -514,6 +514,23 @@ cs_err CAPSTONE_API cs_close(csh *handle)
 	return CS_ERR_OK;
 }
 
+// replace str1 in target with str2; target starts with str1
+// output is put into result (which is array of char with size CS_MNEMONIC_SIZE)
+// return 0 on success, -1 on failure
+static int str_replace(char *result, char *target, const char *str1, char *str2)
+{
+	// only perform replacement if the output fits into result
+	if (strlen(target) - strlen(str1) + strlen(str2) < CS_MNEMONIC_SIZE - 1)  {
+		// copy str2 to begining of result
+		strcpy(result, str2);
+		// skip str1 - already replaced by str2
+		strcat(result, target + strlen(str1));
+
+		return 0;
+	} else
+		return -1;
+}
+
 // fill insn with mnemonic & operands info
 static void fill_insn(struct cs_struct *handle, cs_insn *insn, char *buffer, MCInst *mci,
 		PostPrinter_t postprinter, const uint8_t *code)
@@ -557,9 +574,14 @@ static void fill_insn(struct cs_struct *handle, cs_insn *insn, char *buffer, MCI
 		struct insn_mnem *tmp = handle->mnem_list;
 		while(tmp) {
 			if (tmp->insn.id == insn->id) {
-				// found this instruction, so copy its mnemonic
-				(void)strncpy(insn->mnemonic, tmp->insn.mnemonic, sizeof(insn->mnemonic) - 1);
-				insn->mnemonic[sizeof(insn->mnemonic) - 1] = '\0';
+				char str[CS_MNEMONIC_SIZE];
+
+				if (!str_replace(str, insn->mnemonic, cs_insn_name((csh)handle, insn->id), tmp->insn.mnemonic)) {
+					// copy result to mnemonic
+					(void)strncpy(insn->mnemonic, str, sizeof(insn->mnemonic) - 1);
+					insn->mnemonic[sizeof(insn->mnemonic) - 1] = '\0';
+				}
+
 				break;
 			}
 			tmp = tmp->next;