members pair string : value array [ ] [ elements ] elements value value , elements value string number object array true false null string " " " chars " chars char char chars char UNICODE \ [",\,CTRL] \" \\ \/ \b \f \n \r \t \u hex hex hex hex number int int frac int exp int frac exp int digit onenine digits - digit - onenine digits frac . digits exp e digits hex digit A - F a - f digits digit digit digits e e e+ e- E E+ E- https://www.json.org
members pair string : value array [ ] [ elements ] elements value value , elements value string number object array true false null string " " " chars " chars char char chars char UNICODE \ [",\,CTRL] \" \\ \/ \b \f \n \r \t \u hex hex hex hex number int int frac int exp int frac exp int digit onenine digits - digit - onenine digits frac . digits exp e digits hex digit A - F a - f digits digit digit digits e e e+ e- E E+ E- Example: JSON https://www.json.org
members pair string : value array [ ] [ elements ] elements value value , elements value string number object array true false null string " " " chars " chars char char chars char UNICODE \ [",\,CTRL] \" \\ \/ \b \f \n \r \t \u hex hex hex hex number int int frac int exp int frac exp int digit onenine digits - digit - onenine digits frac . digits exp e digits hex digit A - F a - f digits digit digit digits e e e+ e- E E+ E- Example: JSON https://www.json.org Parsing JSON is a Minefield: http://seriot.ch/
if A determines whether B executes. def parse_csv(s,i): while s[i:]: if is_digit(s[i]): n,j = num(s[i:]) i = i+j else: comma(s[i]) i += 1 CDG for parse_csv
if A determines whether B executes. def parse_csv(s,i): while s[i:]: if is_digit(s[i]): n,j = num(s[i:]) i = i+j else: comma(s[i]) i += 1 CDG for parse_csv while: determines whether if: executes
= i+j else: comma(s[i]) i += 1 CDG for parse_csv Dynamic Control Dependence Tree Each statement execution is represented as a separate node DCD Tree for call parse_csv()
= i+j else: comma(s[i]) i += 1 DCD Tree ~ Parse Tree •No tracking beyond input buffer •Characters are attached to nodes where they are accessed last "12," "12,"
= i+j else: comma(s[i]) i += 1 '1' '2' ',' DCD Tree ~ Parse Tree •No tracking beyond input buffer •Characters are attached to nodes where they are accessed last "12," "12,"
'' while s[i:] and is_digit(s[i]): n += s[i] i = i +1 return i,n def parse_paren(s, i): assert s[i] == '(' i, v = parse_expr(s, i+1) if s[i:] == '': raise Ex(s, i) assert s[i] == ')' return i+1, v def parse_expr(s, i = 0): expr, is_op = [], True while s[i:]: c = s[i] if isdigit(c): if not is_op: raise Ex(s,i) i,num = parse_num(s,i) expr.append(num) is_op = False elif c in ['+', '-', '*', '/']: if is_op: raise Ex(s,i) expr.append(c) is_op, i = True, i + 1 elif c == '(': if not is_op: raise Ex(s,i) i, cexpr = parse_paren(s, i) expr.append(cexpr) is_op = False elif c == ')': break else: raise Ex(s,i) if is_op: raise Ex(s,i) return i, expr 9+3/4 Parse tree for parse_expr('9+3/4')
'' while s[i:] and is_digit(s[i]): n += s[i] i = i +1 return i,n def parse_paren(s, i): assert s[i] == '(' i, v = parse_expr(s, i+1) if s[i:] == '': raise Ex(s, i) assert s[i] == ')' return i+1, v def parse_expr(s, i = 0): expr, is_op = [], True while s[i:]: c = s[i] if isdigit(c): if not is_op: raise Ex(s,i) i,num = parse_num(s,i) expr.append(num) is_op = False elif c in ['+', '-', '*', '/']: if is_op: raise Ex(s,i) expr.append(c) is_op, i = True, i + 1 elif c == '(': if not is_op: raise Ex(s,i) i, cexpr = parse_paren(s, i) expr.append(cexpr) is_op = False elif c == ')': break else: raise Ex(s,i) if is_op: raise Ex(s,i) return i, expr 9+3/4 Parse tree for parse_expr('9+3/4')
'' while s[i:] and is_digit(s[i]): n += s[i] i = i +1 return i,n def parse_paren(s, i): assert s[i] == '(' i, v = parse_expr(s, i+1) if s[i:] == '': raise Ex(s, i) assert s[i] == ')' return i+1, v def parse_expr(s, i = 0): expr, is_op = [], True while s[i:]: c = s[i] if isdigit(c): if not is_op: raise Ex(s,i) i,num = parse_num(s,i) expr.append(num) is_op = False elif c in ['+', '-', '*', '/']: if is_op: raise Ex(s,i) expr.append(c) is_op, i = True, i + 1 elif c == '(': if not is_op: raise Ex(s,i) i, cexpr = parse_paren(s, i) expr.append(cexpr) is_op = False elif c == ')': break else: raise Ex(s,i) if is_op: raise Ex(s,i) return i, expr 9+3/4 Identifying Compatible Nodes Which nodes correspond to the same nonterminal
'' while s[i:] and is_digit(s[i]): n += s[i] i = i +1 return i,n def parse_paren(s, i): assert s[i] == '(' i, v = parse_expr(s, i+1) if s[i:] == '': raise Ex(s, i) assert s[i] == ')' return i+1, v def parse_expr(s, i = 0): expr, is_op = [], True while s[i:]: c = s[i] if isdigit(c): if not is_op: raise Ex(s,i) i,num = parse_num(s,i) expr.append(num) is_op = False elif c in ['+', '-', '*', '/']: if is_op: raise Ex(s,i) expr.append(c) is_op, i = True, i + 1 elif c == '(': if not is_op: raise Ex(s,i) i, cexpr = parse_paren(s, i) expr.append(cexpr) is_op = False elif c == ')': break else: raise Ex(s,i) if is_op: raise Ex(s,i) return i, expr 9+3/4 Identifying Compatible Nodes Which nodes correspond to the same nonterminal
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![Structured Inputs $ ./fuzz [;x1-GPZ+wcckc];,N9J+?#6^6\e?]9lu 2_%'4GX"0VUB[E/r ~fApu6b8<{%siq8Z h.6{V,hr?;{Ti.r3PIxMMMv6{xS^+'Hq! AxB"YXRS@!Kd6;wtAMefFWM(`|J_<1~o} z3K(CCzRH](https://files.speakerdeck.com/presentations/8617c977e4834b71a38ca4093e8c3e49/slide_5.jpg){kind=link}
![def parse_csv(s,i): while s[i:]: if is_digit(s[i]): n,j = num(s[i:]) i](https://files.speakerdeck.com/presentations/8617c977e4834b71a38ca4093e8c3e49/slide_55.jpg){kind=link}
![def parse_csv(s,i): while s[i:]: if is_digit(s[i]): n,j = num(s[i:]) i](https://files.speakerdeck.com/presentations/8617c977e4834b71a38ca4093e8c3e49/slide_56.jpg){kind=link}
![def parse_csv(s,i): while s[i:]: if is_digit(s[i]): n,j = num(s[i:]) i](https://files.speakerdeck.com/presentations/8617c977e4834b71a38ca4093e8c3e49/slide_57.jpg){kind=link}
![def parse_csv(s,i): while s[i:]: if is_digit(s[i]): n,j = num(s[i:]) i](https://files.speakerdeck.com/presentations/8617c977e4834b71a38ca4093e8c3e49/slide_58.jpg){kind=link}
