Setup some simple fuzz helpers for unmarshal.

tools/afl/README.md

@@ -3,12 +3,26 @@
 To use these, you need to install afl (of course), and xterm. A tiling window manager helps manage
 many concurrent fuzzer instances.
 
+Note, afl sometimes requires system configuration, if you find AFL quitting prematurely, try manually
+launching it and addressing any error messages.
+
 ## Fuzz the parser
 ```
 $ sh ./tools/afl/prepare_to_fuzz.sh
-export NFUZZ=1
+$ export NFUZZ=1
 $ sh ./tools/afl/fuzz.sh parser
 Ctrl+C when done to close all fuzzer terminals.
 $ sh ./tools/afl/aggregate_cases.sh parser
 $ ls ./fuzz_out/parser_aggregated/
-```
+```
+
+## Fuzz the unmarshaller
+```
+$ janet ./tools/afl/generate_unmarshal_testcases.janet
+$ sh ./tools/afl/prepare_to_fuzz.sh
+$ export NFUZZ=1
+$ sh ./tools/afl/fuzz.sh unmarshal
+Ctrl+C when done to close all fuzzer terminals.
+$ sh ./tools/afl/aggregate_cases.sh unmarshal
+$ ls ./fuzz_out/unmarshal_aggregated/
+```

tools/afl/generate_unmarshal_testcases.janet

@@ -0,0 +1,49 @@
+
+(os/mkdir "./tools/afl/unmarshal_testcases/")
+
+(defn spit-case [n v]
+  (spit
+    (string "./tools/afl/unmarshal_testcases/" (string n))
+    (marshal v make-image-dict)))
+
+(def cases [
+  nil
+  
+  "abc"
+  
+  :def
+  
+  'hij
+  
+  123
+  
+  (int/s64 123)
+
+  "7"
+
+  [1 2 3]
+
+  @[1 2 3]
+
+  {:a 123}
+
+  @{:b 'xyz}
+  
+  (peg/compile
+    '{:a (* "a" :b "a")
+      :b (* "b" (+ :a 0) "b")
+      :main (* "(" :b ")")})
+  
+  (fn f [a] (fn [] {:ab a}))
+
+  (fn f [a] (print "hello world!"))
+
+  (do
+    (defn f [a] (yield) @[1 "2"])
+    (def fb (fiber/new f))
+    (resume fb)
+    fb)
+])
+
+(eachk i cases
+  (spit-case i (in cases i)))

tools/afl/unmarshal_runner.janet

@@ -0,0 +1,2 @@
+ (pp (unmarshal (slurp ((dyn :args) 1)) load-image-dict))
+