From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Wed, 1 Mar 2017 18:46:52 +0000 (+0000)
Subject: tools/insn-fuzz: Make use of LLVMFuzzerInitialize()
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tools/insn-fuzz: Make use of LLVMFuzzerInitialize()

libfuzz can perform one-time initialisation by calling LLVMFuzzerInitialize().
Move emul_test_init() into this, to avoid repeating it on every
LLVMFuzzerTestOneInput() call.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
---

diff --git a/tools/fuzz/x86_instruction_emulator/afl-harness.c b/tools/fuzz/x86_instruction_emulator/afl-harness.c
index 89d8605fea..63aff5904b 100644
--- a/tools/fuzz/x86_instruction_emulator/afl-harness.c
+++ b/tools/fuzz/x86_instruction_emulator/afl-harness.c
@@ -5,6 +5,7 @@
 #include <string.h>
 #include <getopt.h>
 
+extern int LLVMFuzzerInitialize(int *argc, char ***argv);
 extern int LLVMFuzzerTestOneInput(const uint8_t *data_p, size_t size);
 extern unsigned int fuzz_minimal_input_size(void);
 
@@ -57,6 +58,9 @@ int main(int argc, char **argv)
     else if ( optind != (argc - 1) )
         goto usage;
 
+    if ( LLVMFuzzerInitialize(&argc, &argv) )
+        exit(-1);
+
     if ( fp != stdin ) /* If not using stdin, open the provided file. */
     {
         fp = fopen(argv[optind], "rb");
diff --git a/tools/fuzz/x86_instruction_emulator/fuzz-emul.c b/tools/fuzz/x86_instruction_emulator/fuzz-emul.c
index 4b1e324d06..3b3041d151 100644
--- a/tools/fuzz/x86_instruction_emulator/fuzz-emul.c
+++ b/tools/fuzz/x86_instruction_emulator/fuzz-emul.c
@@ -646,9 +646,19 @@ static void sanitize_input(struct x86_emulate_ctxt *ctxt)
     }
 }
 
+int LLVMFuzzerInitialize(int *argc, char ***argv)
+{
+    if ( !emul_test_init() )
+    {
+        printf("Warning: Stack could not be made executable (%d).\n", errno);
+        return 1;
+    }
+
+    return 0;
+}
+
 int LLVMFuzzerTestOneInput(const uint8_t *data_p, size_t size)
 {
-    bool stack_exec;
     struct cpu_user_regs regs = {};
     struct x86_emulate_ctxt ctxt = {
         .regs = &regs,
@@ -657,13 +667,6 @@ int LLVMFuzzerTestOneInput(const uint8_t *data_p, size_t size)
     };
     int rc;
 
-    stack_exec = emul_test_init();
-    if ( !stack_exec )
-    {
-        printf("Warning: Stack could not be made executable (%d).\n", errno);
-        return 1;
-    }
-
     /* Reset all global state variables */
     memset(&input, 0, sizeof(input));
     data_index = 0;