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// Copyright 2013 Google Inc. All Rights Reserved.
// This file is available under the Apache license.
// Command mgen generates mtail programs for fuzz testing by following a simple grammar.
package main
import (
"flag"
"fmt"
"math/rand"
"github.com/jaqx0r/mtail/internal/runtime/compiler/parser"
)
var (
randSeed = flag.Int64("rand_seed", 1, "Seed to use for math.rand.")
minIterations = flag.Int64("min_iterations", 5000, "Minimum number of iterations before stopping program generation.")
dictionary = flag.Bool("dictionary", false, "Generate a fuzz dictionary to stdout only.")
)
type node struct {
alts [][]string
term string
}
var table = map[string]node{
"start": {[][]string{{"stmt_list"}}, ""},
"stmt_list": {[][]string{{""}, {"stmt_list", "stmt"}}, ""},
"stmt": {[][]string{
{"cond", "{", "stmt_list", "}"},
{"expr"},
{"decl"},
{"def_spec"},
{"deco_spec"},
{"next"},
{"const", "ID", "pattern_expr"},
}, ""},
"expr": {[][]string{{"assign_expr"}}, ""},
"assign_expr": {[][]string{{"rel_expr"}, {"unary_expr", "=", "rel_expr"}, {"unary_expr", "+=", "rel_expr"}}, ""},
"rel_expr": {[][]string{{"additive_expr"}, {"additive_expr", "relop", "additive_expr"}}, ""},
"relop": {[][]string{{"<"}, {">"}, {"<="}, {">="}, {"=="}, {"!="}}, ""},
"additive_expr": {[][]string{{"unary_expr"}, {"additive_expr", "+", "unary_expr"}, {"additive_expr", "-", "unary_expr"}}, ""},
"unary_expr": {[][]string{{"postfix_expr"}, {"BUILTIN", "(", "arg_expr_list", ")"}}, ""},
"arg_expr_list": {[][]string{{""}, {"assign_expr"}, {"arg_expr_list", ",", "assign_expr"}}, ""},
"postfix_expr": {[][]string{{"primary_expr"}, {"postfix_expr", "++"}, {"postfix_expr", "[", "expr", "]"}}, ""},
"primary_expr": {[][]string{{"ID"}, {"CAPREF"}, {"STRING"}, {"(", "expr", ")"}, {"NUMERIC"}}, ""},
"cond": {[][]string{{"pattern_expr"}, {"rel_expr"}}, ""},
"pattern_expr": {[][]string{{"REGEX"}, {"pattern_expr", "+", "REGEX"}, {"pattern_expr", "+", "ID"}}, ""},
"decl": {[][]string{{"hide_spec", "type_spec", "declarator"}}, ""},
"hide_spec": {[][]string{{""}, {"hidden"}}, ""},
"declarator": {[][]string{{"declarator", "by_spec"}, {"declarator", "as_spec"}, {"ID"}, {"STRING"}}, ""},
"type_spec": {[][]string{{"counter"}, {"gauge"}, {"timer"}, {"text"}, {"histogram"}}, ""},
"by_spec": {[][]string{{"by", "by_expr_list"}}, ""},
"by_expr_list": {[][]string{{"ID"}, {"STRING"}, {"by_expr_list", ",", "ID"}, {"by_expr_list", ",", "STRING"}}, ""},
"as_spec": {[][]string{{"as", "STRING"}}, ""},
"def_spec": {[][]string{{"def", "ID", "{", "stmt_list", "}"}}, ""},
"deco_spec": {[][]string{{"deco", "{", "stmt_list", "}"}}, ""},
"BUILTIN": {[][]string{{"strptime"}, {"timestamp"}, {"len"}, {"tolower"}}, ""},
"CAPREF": {[][]string{}, "$1"},
"REGEX": {[][]string{}, "/foo/"},
"STRING": {[][]string{}, "\"bar\""},
"ID": {[][]string{}, "quux"},
"NUMERIC": {[][]string{}, "37"},
}
func emitter(c chan string) {
var l int
for w := range c {
if w == "\n" {
fmt.Println()
}
if w == "" {
continue
}
if l+len(w)+1 >= 80 {
fmt.Println()
fmt.Print(w)
l = len(w)
} else {
if l != 0 {
w = " " + w
}
l += len(w)
fmt.Print(w)
}
}
}
func generateProgram() {
rando := rand.New(rand.NewSource(*randSeed))
c := make(chan string, 1)
go emitter(c)
runs := *minIterations
// Initial state
states := []string{"start"}
// While the state stack is not empty
for len(states) > 0 && runs > 0 {
// Pop the next state
state := states[len(states)-1]
states = states[:len(states)-1]
// fmt.Println("state", state, "states", states)
// Look for the state transition
if n, ok := table[state]; ok {
// If there are state transition alternatives
// fmt.Println("n", n)
if len(n.alts) > 0 {
// Pick a state transition at random
a := rando.Intn(len(n.alts))
// fmt.Println("a", a, n.alts[a], len(n.alts[a]))
// Push the states picked onto the stack (in reverse order)
for i := 0; i < len(n.alts[a]); i++ {
// fmt.Println("i", i, n.alts[a][len(n.alts[a])-i-1])
states = append(states, n.alts[a][len(n.alts[a])-i-1])
}
// fmt.Println("states", states)
} else {
// If there is a terminal, emit it
// fmt.Println("(term)", state, n.term)
c <- n.term
}
} else {
// If the state doesn't exist in the table, treat it as a terminal, and emit it.
// fmt.Println("(state)", state, state)
c <- state
}
runs--
}
c <- "\n"
}
func generateDictionary() {
for _, k := range parser.Dictionary() {
fmt.Printf("\"%s\"\n", k)
}
}
func main() {
flag.Parse()
if *dictionary {
generateDictionary()
} else {
generateProgram()
}
}
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