kmicinski

; I took most of this from Matt Might's:
; http://matt.might.net/articles/lexers-in-racket/
#lang racket
(require parser-tools/lex)
(require (prefix-in : parser-tools/lex-sre))

;(struct char (c) #:)

(define lex
 (lexer

kmicinski

// gcc cpyarg.c -o cpyarg
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void gadgets() {
  int y = 0;
  char *x = 0;
  asm("popq %rsi\n"
      "ret\n"

kmicinski

// Note that I am using:
// https://github.com/francoiscolas/multipart-parser
// Assuming it is compiled in subdirectory multipart-parser, I compile with:
// gcc server_example.c multipart-parser/multipartparser.o

// Standard C libraries
#include <stdio.h>
#include <stdlib.h>

// Various POSIX libraries

kmicinski

>>> x = [[0] * 3] * 3
>>> x[1][1] = 3
>>> x
[[0, 3, 0], [0, 3, 0], [0, 3, 0]]

kmicinski

def isEmpty(lst): return len(lst) == 0

def hd(lst): return lst[0]

def tl(lst): return lst[1:]

# Return the reverse of lst
def reverse(lst): return []

# Find the minimum element of the list

kmicinski

# Prove that the cost of this function is O(n)
#
# Prove that this function computes a result x' such that:
#      x' = x * (x+1) / 2
def e(x):
    if (x == 0): return 0
    return: x + e(x - 1)

# Prove that the return value of this function is a list l' such that:
#    forall i < len(l). l'[i] = 2 * l[i]

kmicinski

method foo(argument1, argument2) {
    r1 = argument1.baz();
    if (r1) {
      r2 = 3;
    }
    if (argument2.bar()) {
      // We want the taint here to be `argument2.bar()` rather than 
      // argument2.bar() /\ argument1.baz()
      useCamera();
    }

kmicinski

CS107 -- Exam 1 Practice

Here are some practice problems for the upcoming exam. These are somewhat representative, but won't be precisely what's on the exam: they exercise the same kinds of ideas.

I'll just do a quick dump of problems. I won't be giving a key right now, because my experience is that studnets don't work the questions but just look at the key if they have one. I am happy to check your answers if you write them up. I'll also comment on problems a bit tomorrow.

1. In git, briefly explain what a merge conflict is and how you might fix it. You do not need to

kmicinski

#lang racket

(define (find-redexes e)
  (match e
    [`(λ (,x) ,body) (find-redexes body)]
    [(? symbol? x) (void)]
    [`((λ (,x) ,body) ,arg)
     (begin
       (display "I found this redex!\n")
       (pretty-print e)

kmicinski

; Some church-encoding hints
#lang racket

(define (build-an-argument-list arg-list f)
  (match arg-list
    [(list x)      `(,f ,x)]
    [`(,hd . ,tl)  `(,(build-an-argument-list tl f) ,hd)]))

(match '(2 3 5)
  [`(,f . ,args) args])