lab util grade 100

.gitignore

@@ -15,3 +15,12 @@ mkfs
 kernel/kernel
 user/usys.S
 .gdbinit
+myapi.key
+*-handin.tar.gz
+xv6.out*
+.vagrant/
+submissions/
+ph
+barrier
+/lab-*.json
+.DS_Store

Makefile

@@ -1,14 +1,16 @@
+
+# To compile and run with a lab solution, set the lab name in conf/lab.mk
+# (e.g., LAB=util).  Run make grade to test solution with the lab's
+# grade script (e.g., grade-lab-util).
+
+-include conf/lab.mk
+
 K=kernel
 U=user
 
 OBJS = \
   $K/entry.o \
-  $K/start.o \
-  $K/console.o \
-  $K/printf.o \
-  $K/uart.o \
   $K/kalloc.o \
-  $K/spinlock.o \
   $K/string.o \
   $K/main.o \
   $K/vm.o \
@@ -30,6 +32,34 @@ OBJS = \
   $K/plic.o \
   $K/virtio_disk.o
 
+OBJS_KCSAN = \
+  $K/start.o \
+  $K/console.o \
+  $K/printf.o \
+  $K/uart.o \
+  $K/spinlock.o
+
+ifdef KCSAN
+OBJS_KCSAN += \
+	$K/kcsan.o
+endif
+
+ifeq ($(LAB),$(filter $(LAB), lock))
+OBJS += \
+	$K/stats.o\
+	$K/sprintf.o
+endif
+
+
+ifeq ($(LAB),net)
+OBJS += \
+	$K/e1000.o \
+	$K/net.o \
+	$K/sysnet.o \
+	$K/pci.o
+endif
+
+
 # riscv64-unknown-elf- or riscv64-linux-gnu-
 # perhaps in /opt/riscv/bin
 #TOOLPREFIX = 
@@ -57,12 +87,28 @@ OBJCOPY = $(TOOLPREFIX)objcopy
 OBJDUMP = $(TOOLPREFIX)objdump
 
 CFLAGS = -Wall -Werror -O -fno-omit-frame-pointer -ggdb -gdwarf-2
+
+ifdef LAB
+LABUPPER = $(shell echo $(LAB) | tr a-z A-Z)
+XCFLAGS += -DSOL_$(LABUPPER) -DLAB_$(LABUPPER)
+endif
+
+CFLAGS += $(XCFLAGS)
 CFLAGS += -MD
 CFLAGS += -mcmodel=medany
 CFLAGS += -ffreestanding -fno-common -nostdlib -mno-relax
 CFLAGS += -I.
 CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
 
+ifeq ($(LAB),net)
+CFLAGS += -DNET_TESTS_PORT=$(SERVERPORT)
+endif
+
+ifdef KCSAN
+CFLAGS += -DKCSAN
+KCSANFLAG = -fsanitize=thread
+endif
+
 # Disable PIE when possible (for Ubuntu 16.10 toolchain)
 ifneq ($(shell $(CC) -dumpspecs 2>/dev/null | grep -e '[^f]no-pie'),)
 CFLAGS += -fno-pie -no-pie
@@ -73,11 +119,17 @@ endif
 
 LDFLAGS = -z max-page-size=4096
 
-$K/kernel: $(OBJS) $K/kernel.ld $U/initcode
-	$(LD) $(LDFLAGS) -T $K/kernel.ld -o $K/kernel $(OBJS) 
+$K/kernel: $(OBJS) $(OBJS_KCSAN) $K/kernel.ld $U/initcode
+	$(LD) $(LDFLAGS) -T $K/kernel.ld -o $K/kernel $(OBJS) $(OBJS_KCSAN)
 	$(OBJDUMP) -S $K/kernel > $K/kernel.asm
 	$(OBJDUMP) -t $K/kernel | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $K/kernel.sym
 
+$(OBJS): EXTRAFLAG := $(KCSANFLAG)
+
+$K/%.o: $K/%.c
+	$(CC) $(CFLAGS) $(EXTRAFLAG) -c -o $@ $<
+
+
 $U/initcode: $U/initcode.S
 	$(CC) $(CFLAGS) -march=rv64g -nostdinc -I. -Ikernel -c $U/initcode.S -o $U/initcode.o
 	$(LD) $(LDFLAGS) -N -e start -Ttext 0 -o $U/initcode.out $U/initcode.o
@@ -89,6 +141,10 @@ tags: $(OBJS) _init
 
 ULIB = $U/ulib.o $U/usys.o $U/printf.o $U/umalloc.o
 
+ifeq ($(LAB),$(filter $(LAB), lock))
+ULIB += $U/statistics.o
+endif
+
 _%: %.o $(ULIB)
 	$(LD) $(LDFLAGS) -T $U/user.ld -o $@ $^
 	$(OBJDUMP) -S $@ > $*.asm
@@ -107,7 +163,7 @@ $U/_forktest: $U/forktest.o $(ULIB)
 	$(OBJDUMP) -S $U/_forktest > $U/forktest.asm
 
 mkfs/mkfs: mkfs/mkfs.c $K/fs.h $K/param.h
-	gcc -Werror -Wall -I. -o mkfs/mkfs mkfs/mkfs.c
+	gcc $(XCFLAGS) -Werror -Wall -I. -o mkfs/mkfs mkfs/mkfs.c
 
 # Prevent deletion of intermediate files, e.g. cat.o, after first build, so
 # that disk image changes after first build are persistent until clean.  More
@@ -132,9 +188,85 @@ UPROGS=\
 	$U/_grind\
 	$U/_wc\
 	$U/_zombie\
+	$U/_sleep\
+	$U/_pingpong\
+	$U/_primes\
+	$U/_find\
+	$U/_xargs\
 
-fs.img: mkfs/mkfs README $(UPROGS)
-	mkfs/mkfs fs.img README $(UPROGS)
+
+
+
+ifeq ($(LAB),$(filter $(LAB), lock))
+UPROGS += \
+	$U/_stats
+endif
+
+ifeq ($(LAB),traps)
+UPROGS += \
+	$U/_call\
+	$U/_bttest
+endif
+
+ifeq ($(LAB),lazy)
+UPROGS += \
+	$U/_lazytests
+endif
+
+ifeq ($(LAB),cow)
+UPROGS += \
+	$U/_cowtest
+endif
+
+ifeq ($(LAB),thread)
+UPROGS += \
+	$U/_uthread
+
+$U/uthread_switch.o : $U/uthread_switch.S
+	$(CC) $(CFLAGS) -c -o $U/uthread_switch.o $U/uthread_switch.S
+
+$U/_uthread: $U/uthread.o $U/uthread_switch.o $(ULIB)
+	$(LD) $(LDFLAGS) -N -e main -Ttext 0 -o $U/_uthread $U/uthread.o $U/uthread_switch.o $(ULIB)
+	$(OBJDUMP) -S $U/_uthread > $U/uthread.asm
+
+ph: notxv6/ph.c
+	gcc -o ph -g -O2 $(XCFLAGS) notxv6/ph.c -pthread
+
+barrier: notxv6/barrier.c
+	gcc -o barrier -g -O2 $(XCFLAGS) notxv6/barrier.c -pthread
+endif
+
+ifeq ($(LAB),pgtbl)
+UPROGS += \
+	$U/_pgtbltest
+endif
+
+ifeq ($(LAB),lock)
+UPROGS += \
+	$U/_kalloctest\
+	$U/_bcachetest
+endif
+
+ifeq ($(LAB),fs)
+UPROGS += \
+	$U/_bigfile
+endif
+
+
+
+ifeq ($(LAB),net)
+UPROGS += \
+	$U/_nettests
+endif
+
+UEXTRA=
+ifeq ($(LAB),util)
+	UEXTRA += user/xargstest.sh
+endif
+
+
+fs.img: mkfs/mkfs README $(UEXTRA) $(UPROGS)
+	mkfs/mkfs fs.img README $(UEXTRA) $(UPROGS)
 
 -include kernel/*.d user/*.d
 
@@ -144,7 +276,8 @@ clean:
 	$U/initcode $U/initcode.out $K/kernel fs.img \
 	mkfs/mkfs .gdbinit \
         $U/usys.S \
-	$(UPROGS)
+	$(UPROGS) \
+	ph barrier
 
 # try to generate a unique GDB port
 GDBPORT = $(shell expr `id -u` % 5000 + 25000)
@@ -155,12 +288,22 @@ QEMUGDB = $(shell if $(QEMU) -help | grep -q '^-gdb'; \
 ifndef CPUS
 CPUS := 3
 endif
+ifeq ($(LAB),fs)
+CPUS := 1
+endif
+
+FWDPORT = $(shell expr `id -u` % 5000 + 25999)
 
 QEMUOPTS = -machine virt -bios none -kernel $K/kernel -m 128M -smp $(CPUS) -nographic
 QEMUOPTS += -global virtio-mmio.force-legacy=false
 QEMUOPTS += -drive file=fs.img,if=none,format=raw,id=x0
 QEMUOPTS += -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
 
+ifeq ($(LAB),net)
+QEMUOPTS += -netdev user,id=net0,hostfwd=udp::$(FWDPORT)-:2000 -object filter-dump,id=net0,netdev=net0,file=packets.pcap
+QEMUOPTS += -device e1000,netdev=net0,bus=pcie.0
+endif
+
 qemu: $K/kernel fs.img
 	$(QEMU) $(QEMUOPTS)
 
@@ -171,3 +314,102 @@ qemu-gdb: $K/kernel .gdbinit fs.img
 	@echo "*** Now run 'gdb' in another window." 1>&2
 	$(QEMU) $(QEMUOPTS) -S $(QEMUGDB)
 
+ifeq ($(LAB),net)
+# try to generate a unique port for the echo server
+SERVERPORT = $(shell expr `id -u` % 5000 + 25099)
+
+server:
+	python3 server.py $(SERVERPORT)
+
+ping:
+	python3 ping.py $(FWDPORT)
+endif
+
+##
+##  FOR testing lab grading script
+##
+
+ifneq ($(V),@)
+GRADEFLAGS += -v
+endif
+
+print-gdbport:
+	@echo $(GDBPORT)
+
+grade:
+	@echo $(MAKE) clean
+	@$(MAKE) clean || \
+          (echo "'make clean' failed.  HINT: Do you have another running instance of xv6?" && exit 1)
+	./grade-lab-$(LAB) $(GRADEFLAGS)
+
+##
+## FOR web handin
+##
+
+
+WEBSUB := https://6828.scripts.mit.edu/2022/handin.py
+
+handin: tarball-pref myapi.key
+	@SUF=$(LAB); \
+	curl -f -F file=@lab-$$SUF-handin.tar.gz -F key=\<myapi.key $(WEBSUB)/upload \
+	    > /dev/null || { \
+		echo ; \
+		echo Submit seems to have failed.; \
+		echo Please go to $(WEBSUB)/ and upload the tarball manually.; }
+
+handin-check:
+	@if ! test -d .git; then \
+		echo No .git directory, is this a git repository?; \
+		false; \
+	fi
+	@if test "$$(git symbolic-ref HEAD)" != refs/heads/$(LAB); then \
+		git branch; \
+		read -p "You are not on the $(LAB) branch.  Hand-in the current branch? [y/N] " r; \
+		test "$$r" = y; \
+	fi
+	@if ! git diff-files --quiet || ! git diff-index --quiet --cached HEAD; then \
+		git status -s; \
+		echo; \
+		echo "You have uncomitted changes.  Please commit or stash them."; \
+		false; \
+	fi
+	@if test -n "`git status -s`"; then \
+		git status -s; \
+		read -p "Untracked files will not be handed in.  Continue? [y/N] " r; \
+		test "$$r" = y; \
+	fi
+
+UPSTREAM := $(shell git remote -v | grep -m 1 "xv6-labs-2022" | awk '{split($$0,a," "); print a[1]}')
+
+tarball: handin-check
+	git archive --format=tar HEAD | gzip > lab-$(LAB)-handin.tar.gz
+
+tarball-pref: handin-check
+	@SUF=$(LAB); \
+	git archive --format=tar HEAD > lab-$$SUF-handin.tar; \
+	git diff $(UPSTREAM)/$(LAB) > /tmp/lab-$$SUF-diff.patch; \
+	tar -rf lab-$$SUF-handin.tar /tmp/lab-$$SUF-diff.patch; \
+	gzip -c lab-$$SUF-handin.tar > lab-$$SUF-handin.tar.gz; \
+	rm lab-$$SUF-handin.tar; \
+	rm /tmp/lab-$$SUF-diff.patch; \
+
+myapi.key:
+	@echo Get an API key for yourself by visiting $(WEBSUB)/
+	@read -p "Please enter your API key: " k; \
+	if test `echo "$$k" |tr -d '\n' |wc -c` = 32 ; then \
+		TF=`mktemp -t tmp.XXXXXX`; \
+		if test "x$$TF" != "x" ; then \
+			echo "$$k" |tr -d '\n' > $$TF; \
+			mv -f $$TF $@; \
+		else \
+			echo mktemp failed; \
+			false; \
+		fi; \
+	else \
+		echo Bad API key: $$k; \
+		echo An API key should be 32 characters long.; \
+		false; \
+	fi;
+
+
+.PHONY: handin tarball tarball-pref clean grade handin-check

conf/lab.mk

@@ -0,0 +1 @@
+LAB=util

grade-lab-util

@@ -0,0 +1,86 @@
+#!/usr/bin/env python3
+
+import re
+from gradelib import *
+
+r = Runner(save("xv6.out"))
+
+@test(5, "sleep, no arguments")
+def test_sleep_no_args():
+    r.run_qemu(shell_script([
+        'sleep'
+    ]))
+    r.match(no=["exec .* failed", "$ sleep\n$"])
+
+@test(5, "sleep, returns")
+def test_sleep_no_args():
+    r.run_qemu(shell_script([
+        'sleep',
+        'echo OK'
+    ]))
+    r.match('^OK$', no=["exec .* failed", "$ sleep\n$"])
+
+@test(10, "sleep, makes syscall")
+def test_sleep():
+    r.run_qemu(shell_script([
+        'sleep 10',
+        'echo FAIL'
+    ]), stop_breakpoint('sys_sleep'))
+    r.match('\\$ sleep 10', no=['FAIL'])
+
+@test(20, "pingpong")
+def test_pingpong():
+    r.run_qemu(shell_script([
+        'pingpong', 'echo OK'
+    ]))
+    r.match('^\\d+: received ping$', '^\\d+: received pong$', '^OK$')
+
+@test(20, "primes")
+def test_primes():
+    r.run_qemu(shell_script([
+        'primes', 'echo OK'
+    ]))
+    args = ['prime %d' % i for i in [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31]]
+    args.append('^OK$')
+    r.match(*args)
+
+@test(10, "find, in current directory")
+def test_find_curdir():
+    fn = random_str()
+    r.run_qemu(shell_script([
+        'echo > %s' % fn,
+        'find . %s' % fn
+    ]))
+    r.match('./%s' % fn)
+
+@test(10, "find, recursive")
+def test_find_recursive():
+    needle = random_str()
+    dirs = [random_str() for _ in range(3)]
+    r.run_qemu(shell_script([
+        'mkdir %s' % dirs[0],
+        'echo > %s/%s' % (dirs[0], needle),
+        'mkdir %s/%s' % (dirs[0], dirs[1]),
+        'echo > %s/%s/%s' % (dirs[0], dirs[1], needle),
+        'mkdir %s' % dirs[2],
+        'echo > %s/%s' % (dirs[2], needle),
+        'find . %s' % needle
+    ]))
+    r.match('./%s/%s' % (dirs[0], needle),
+            './%s/%s/%s' % (dirs[0], dirs[1], needle),
+            './%s/%s' % (dirs[2], needle))
+
+@test(19, "xargs")
+def test_xargs():
+    r.run_qemu(shell_script([
+        'sh < xargstest.sh',
+        'echo DONE',
+    ], 'DONE'))
+    matches = re.findall("hello", r.qemu.output)
+    assert_equal(len(matches), 3, "Number of appearances of 'hello'")
+
+@test(1, "time")
+def test_time():
+    check_time()
+    
+run_tests()

gradelib.py

@@ -0,0 +1,611 @@
+from __future__ import print_function
+
+import sys, os, re, time, socket, select, subprocess, errno, shutil, random, string
+from subprocess import check_call, Popen
+from optparse import OptionParser
+
+__all__ = []
+
+##################################################################
+# Test structure
+#
+
+__all__ += ["test", "end_part", "run_tests", "get_current_test"]
+
+TESTS = []
+TOTAL = POSSIBLE = 0
+PART_TOTAL = PART_POSSIBLE = 0
+CURRENT_TEST = None
+
+def test(points, title=None, parent=None):
+    """Decorator for declaring test functions.  If title is None, the
+    title of the test will be derived from the function name by
+    stripping the leading "test_" and replacing underscores with
+    spaces."""
+
+    def register_test(fn, title=title):
+        if not title:
+            assert fn.__name__.startswith("test_")
+            title = fn.__name__[5:].replace("_", " ")
+        if parent:
+            title = "  " + title
+
+        def run_test():
+            global TOTAL, POSSIBLE, CURRENT_TEST
+
+            # Handle test dependencies
+            if run_test.complete:
+                return run_test.ok
+            run_test.complete = True
+            parent_failed = False
+            if parent:
+                parent_failed = not parent()
+
+            # Run the test
+            fail = None
+            start = time.time()
+            CURRENT_TEST = run_test
+            sys.stdout.write("== Test %s == " % title)
+            if parent:
+                sys.stdout.write("\n")
+            sys.stdout.flush()
+            try:
+                if parent_failed:
+                    raise AssertionError('Parent failed: %s' % parent.__name__)
+                fn()
+            except AssertionError as e:
+                fail = str(e)
+
+            # Display and handle test result
+            POSSIBLE += points
+            if points:
+                print("%s: %s" % (title, \
+                    (color("red", "FAIL") if fail else color("green", "OK"))), end=' ')
+            if time.time() - start > 0.1:
+                print("(%.1fs)" % (time.time() - start), end=' ')
+            print()
+            if fail:
+                print("    %s" % fail.replace("\n", "\n    "))
+            else:
+                TOTAL += points
+            for callback in run_test.on_finish:
+                callback(fail)
+            CURRENT_TEST = None
+
+            run_test.ok = not fail
+            return run_test.ok
+
+        # Record test metadata on the test wrapper function
+        run_test.__name__ = fn.__name__
+        run_test.title = title
+        run_test.complete = False
+        run_test.ok = False
+        run_test.on_finish = []
+        TESTS.append(run_test)
+        return run_test
+    return register_test
+
+def end_part(name):
+    def show_part():
+        global PART_TOTAL, PART_POSSIBLE
+        print("Part %s score: %d/%d" % \
+            (name, TOTAL - PART_TOTAL, POSSIBLE - PART_POSSIBLE))
+        print()
+        PART_TOTAL, PART_POSSIBLE = TOTAL, POSSIBLE
+    show_part.title = ""
+    TESTS.append(show_part)
+
+def run_tests():
+    """Set up for testing and run the registered test functions."""
+
+    # Handle command line
+    global options
+    parser = OptionParser(usage="usage: %prog [-v] [filters...]")
+    parser.add_option("-v", "--verbose", action="store_true",
+                      help="print commands")
+    parser.add_option("--color", choices=["never", "always", "auto"],
+                      default="auto", help="never, always, or auto")
+    (options, args) = parser.parse_args()
+
+    # Start with a full build to catch build errors
+    make()
+
+    # Clean the file system if there is one
+    reset_fs()
+
+    # Run tests
+    limit = list(map(str.lower, args))
+    try:
+        for test in TESTS:
+            if not limit or any(l in test.title.lower() for l in limit):
+                test()
+        if not limit:
+            print("Score: %d/%d" % (TOTAL, POSSIBLE))
+    except KeyboardInterrupt:
+        pass
+    if TOTAL < POSSIBLE:
+        sys.exit(1)
+
+def get_current_test():
+    if not CURRENT_TEST:
+        raise RuntimeError("No test is running")
+    return CURRENT_TEST
+
+##################################################################
+# Assertions
+#
+
+__all__ += ["assert_equal", "assert_lines_match"]
+
+def assert_equal(got, expect, msg=""):
+    if got == expect:
+        return
+    if msg:
+        msg += "\n"
+    raise AssertionError("%sgot:\n  %s\nexpected:\n  %s" %
+                         (msg, str(got).replace("\n", "\n  "),
+                          str(expect).replace("\n", "\n  ")))
+
+def assert_lines_match(text, *regexps, **kw):
+    """Assert that all of regexps match some line in text.  If a 'no'
+    keyword argument is given, it must be a list of regexps that must
+    *not* match any line in text."""
+
+    def assert_lines_match_kw(no=[]):
+        return no
+    no = assert_lines_match_kw(**kw)
+
+    # Check text against regexps
+    lines = text.splitlines()
+    good = set()
+    bad = set()
+    for i, line in enumerate(lines):
+        if any(re.match(r, line) for r in regexps):
+            good.add(i)
+            regexps = [r for r in regexps if not re.match(r, line)]
+        if any(re.match(r, line) for r in no):
+            bad.add(i)
+
+    if not regexps and not bad:
+        return
+
+    # We failed; construct an informative failure message
+    show = set()
+    for lineno in good.union(bad):
+        for offset in range(-2, 3):
+            show.add(lineno + offset)
+    if regexps:
+        show.update(n for n in range(len(lines) - 5, len(lines)))
+
+    msg = []
+    last = -1
+    for lineno in sorted(show):
+        if 0 <= lineno < len(lines):
+            if lineno != last + 1:
+                msg.append("...")
+            last = lineno
+            msg.append("%s %s" % (color("red", "BAD ") if lineno in bad else
+                                  color("green", "GOOD") if lineno in good
+                                  else "    ",
+                                  lines[lineno]))
+    if last != len(lines) - 1:
+        msg.append("...")
+    if bad:
+        msg.append("unexpected lines in output")
+    for r in regexps:
+        msg.append(color("red", "MISSING") + " '%s'" % r)
+    raise AssertionError("\n".join(msg))
+
+##################################################################
+# Utilities
+#
+
+__all__ += ["make", "maybe_unlink", "reset_fs", "color", "random_str", "check_time", "check_answers"]
+
+MAKE_TIMESTAMP = 0
+
+def pre_make():
+    """Delay prior to running make to ensure file mtimes change."""
+    while int(time.time()) == MAKE_TIMESTAMP:
+        time.sleep(0.1)
+
+def post_make():
+    """Record the time after make completes so that the next run of
+    make can be delayed if needed."""
+    global MAKE_TIMESTAMP
+    MAKE_TIMESTAMP = int(time.time())
+
+def make(*target):
+    pre_make()
+    if Popen(("make",) + target).wait():
+        sys.exit(1)
+    post_make()
+
+def show_command(cmd):
+    from pipes import quote
+    print("\n$", " ".join(map(quote, cmd)))
+
+def maybe_unlink(*paths):
+    for path in paths:
+        try:
+            os.unlink(path)
+        except EnvironmentError as e:
+            if e.errno != errno.ENOENT:
+                raise
+
+COLORS = {"default": "\033[0m", "red": "\033[31m", "green": "\033[32m"}
+
+def color(name, text):
+    if options.color == "always" or (options.color == "auto" and os.isatty(1)):
+        return COLORS[name] + text + COLORS["default"]
+    return text
+
+def reset_fs():
+    if os.path.exists("obj/fs/clean-fs.img"):
+        shutil.copyfile("obj/fs/clean-fs.img", "obj/fs/fs.img")
+
+def random_str(n=8):
+    letters = string.ascii_letters + string.digits
+    return ''.join(random.choice(letters) for _ in range(n))
+
+def check_time():
+    try:
+        print("")
+        with open('time.txt') as f:
+            d = f.read().strip()
+            if not re.match(r'^\d+$', d):
+                raise AssertionError('time.txt does not contain a single integer (number of hours spent on the lab)')
+    except IOError:
+        raise AssertionError('Cannot read time.txt')
+
+def check_answers(file, n=10):
+    try:
+        with open(file) as f:
+            d = f.read().strip()
+            if len(d) < n:
+                raise AssertionError('%s does not seem to contain enough text' % file)
+    except IOError:
+        raise AssertionError('Cannot read %s' % file)
+
+
+##################################################################
+# Controllers
+#
+
+__all__ += ["QEMU", "GDBClient"]
+
+class QEMU(object):
+    _GDBPORT = None
+
+    def __init__(self, *make_args):
+        # Check that QEMU is not currently running
+        try:
+            GDBClient(self.get_gdb_port(), timeout=0).close()
+        except socket.error:
+            pass
+        else:
+            print("""\
+GDB stub found on port %d.
+QEMU appears to already be running.  Please exit it if possible or use
+'killall qemu' or 'killall qemu.real'.""" % self.get_gdb_port(), file=sys.stderr)
+            sys.exit(1)
+
+        if options.verbose:
+            show_command(("make",) + make_args)
+        cmd = ("make", "-s", "--no-print-directory") + make_args
+        self.proc = Popen(cmd, stdout=subprocess.PIPE,
+                          stderr=subprocess.STDOUT,
+                          stdin=subprocess.PIPE)
+        # Accumulated output as a string
+        self.output = ""
+        # Accumulated output as a bytearray
+        self.outbytes = bytearray()
+        self.on_output = []
+
+    @staticmethod
+    def get_gdb_port():
+        if QEMU._GDBPORT is None:
+            p = Popen(["make", "-s", "--no-print-directory", "print-gdbport"],
+                      stdout=subprocess.PIPE)
+            (out, _) = p.communicate()
+            if p.returncode:
+                raise RuntimeError(
+                    "Failed to get gdbport: make exited with %d" %
+                    p.returncode)
+            QEMU._GDBPORT = int(out)
+        return QEMU._GDBPORT
+
+    def fileno(self):
+        if self.proc:
+            return self.proc.stdout.fileno()
+
+    def handle_read(self):
+        buf = os.read(self.proc.stdout.fileno(), 4096)
+        self.outbytes.extend(buf)
+        self.output = self.outbytes.decode("utf-8", "replace")
+        for callback in self.on_output:
+            callback(buf)
+        if buf == b"":
+            self.wait()
+            return
+
+    def write(self, buf):
+        if isinstance(buf, str):
+            buf = buf.encode('utf-8')
+        self.proc.stdin.write(buf)
+        self.proc.stdin.flush()
+
+    def wait(self):
+        if self.proc:
+            self.proc.wait()
+            self.proc = None
+
+    def kill(self):
+        if self.proc:
+            self.proc.terminate()
+
+class GDBClient(object):
+    def __init__(self, port, timeout=15):
+        start = time.time()
+        while True:
+            self.sock = socket.socket()
+            try:
+                self.sock.settimeout(1)
+                self.sock.connect(("localhost", port))
+                break
+            except socket.error:
+                if time.time() >= start + timeout:
+                    raise
+        self.__buf = ""
+
+    def fileno(self):
+        if self.sock:
+            return self.sock.fileno()
+
+    def handle_read(self):
+        try:
+            data = self.sock.recv(4096).decode("ascii", "replace")
+        except socket.error:
+            data = ""
+        if data == "":
+            self.sock.close()
+            self.sock = None
+            return
+        self.__buf += data
+
+        while True:
+            m = re.search(r"\$([^#]*)#[0-9a-zA-Z]{2}", self.__buf)
+            if not m:
+                break
+            pkt = m.group(1)
+            self.__buf = self.__buf[m.end():]
+
+            if pkt.startswith("T05"):
+                # Breakpoint
+                raise TerminateTest
+
+    def __send(self, cmd):
+        packet = "$%s#%02x" % (cmd, sum(map(ord, cmd)) % 256)
+        self.sock.sendall(packet.encode("ascii"))
+
+    def __send_break(self):
+        self.sock.sendall(b"\x03")
+
+    def close(self):
+        if self.sock:
+            self.sock.close()
+            self.sock = None
+
+    def cont(self):
+        self.__send("c")
+
+    def breakpoint(self, addr):
+        self.__send("Z1,%x,1" % addr)
+
+
+##################################################################
+# QEMU test runner
+#
+
+__all__ += ["TerminateTest", "Runner"]
+
+class TerminateTest(Exception):
+    pass
+
+class Runner():
+    def __init__(self, *default_monitors):
+        self.__default_monitors = default_monitors
+
+    def run_qemu(self, *monitors, **kw):
+        """Run a QEMU-based test.  monitors should functions that will
+        be called with this Runner instance once QEMU and GDB are
+        started.  Typically, they should register callbacks that throw
+        TerminateTest when stop events occur.  The target_base
+        argument gives the make target to run.  The make_args argument
+        should be a list of additional arguments to pass to make.  The
+        timeout argument bounds how long to run before returning."""
+
+        def run_qemu_kw(target_base="qemu", make_args=[], timeout=30):
+            return target_base, make_args, timeout
+        target_base, make_args, timeout = run_qemu_kw(**kw)
+
+        # Start QEMU
+        pre_make()
+        self.qemu = QEMU(target_base + "-gdb", *make_args)
+        self.gdb = None
+
+        try:
+            # Wait for QEMU to start or make to fail.  This will set
+            # self.gdb if QEMU starts.
+            self.qemu.on_output = [self.__monitor_start]
+            self.__react([self.qemu], timeout=90)
+            self.qemu.on_output = []
+            if self.gdb is None:
+                print("Failed to connect to QEMU; output:")
+                print(self.qemu.output)
+                sys.exit(1)
+            post_make()
+
+            # QEMU and GDB are up
+            self.reactors = [self.qemu, self.gdb]
+
+            # Start monitoring
+            for m in self.__default_monitors + monitors:
+                m(self)
+
+            # Run and react
+            self.gdb.cont()
+            self.__react(self.reactors, timeout)
+        finally:
+            # Shutdown QEMU
+            try:
+                if self.gdb is None:
+                    sys.exit(1)
+                self.qemu.kill()
+                self.__react(self.reactors, 5)
+                self.gdb.close()
+                self.qemu.wait()
+            except:
+                print("""\
+Failed to shutdown QEMU.  You might need to 'killall qemu' or
+'killall qemu.real'.
+""")
+                raise
+
+    def __monitor_start(self, output):
+        if b"\n" in output:
+            try:
+                self.gdb = GDBClient(self.qemu.get_gdb_port(), timeout=2)
+                raise TerminateTest
+            except socket.error:
+                pass
+        if not len(output):
+            raise TerminateTest
+
+    def __react(self, reactors, timeout):
+        deadline = time.time() + timeout
+        try:
+            while True:
+                timeleft = deadline - time.time()
+                if timeleft < 0:
+                    sys.stdout.write("Timeout! ")
+                    sys.stdout.flush()
+                    return
+
+                rset = [r for r in reactors if r.fileno() is not None]
+                if not rset:
+                    return
+
+                rset, _, _ = select.select(rset, [], [], timeleft)
+                for reactor in rset:
+                    reactor.handle_read()
+        except TerminateTest:
+            pass
+
+    def user_test(self, binary, *monitors, **kw):
+        """Run a user test using the specified binary.  Monitors and
+        keyword arguments are as for run_qemu.  This runs on a disk
+        snapshot unless the keyword argument 'snapshot' is False."""
+
+        maybe_unlink("obj/kern/init.o", "obj/kern/kernel")
+        if kw.pop("snapshot", True):
+            kw.setdefault("make_args", []).append("QEMUEXTRA+=-snapshot")
+        self.run_qemu(target_base="run-%s" % binary, *monitors, **kw)
+
+    def match(self, *args, **kwargs):
+        """Shortcut to call assert_lines_match on the most recent QEMU
+        output."""
+
+        assert_lines_match(self.qemu.output, *args, **kwargs)
+
+##################################################################
+# Monitors
+#
+
+__all__ += ["save", "stop_breakpoint", "call_on_line", "stop_on_line", "shell_script"]
+
+def save(path):
+    """Return a monitor that writes QEMU's output to path.  If the
+    test fails, copy the output to path.test-name."""
+
+    def setup_save(runner):
+        f.seek(0)
+        f.truncate()
+        runner.qemu.on_output.append(f.write)
+        get_current_test().on_finish.append(save_on_finish)
+
+    def save_on_finish(fail):
+        f.flush()
+        save_path = path + "." + get_current_test().__name__[5:]
+        if fail:
+            shutil.copyfile(path, save_path)
+            print("    QEMU output saved to %s" % save_path)
+        elif os.path.exists(save_path):
+            os.unlink(save_path)
+            print("    (Old %s failure log removed)" % save_path)
+
+    f = open(path, "wb")
+    return setup_save
+
+def stop_breakpoint(addr):
+    """Returns a monitor that stops when addr is reached.  addr may be
+    a number or the name of a symbol."""
+
+    def setup_breakpoint(runner):
+        if isinstance(addr, str):
+            addrs = [int(sym[:16], 16) for sym in open("kernel/kernel.sym")
+                     if sym[17:].strip() == addr]
+            assert len(addrs), "Symbol %s not found" % addr
+            runner.gdb.breakpoint(addrs[0])
+        else:
+            runner.gdb.breakpoint(addr)
+    return setup_breakpoint
+
+def call_on_line(regexp, callback):
+    """Returns a monitor that calls 'callback' when QEMU prints a line
+    matching 'regexp'."""
+
+    def setup_call_on_line(runner):
+        buf = bytearray()
+        def handle_output(output):
+            buf.extend(output)
+            while b"\n" in buf:
+                line, buf[:] = buf.split(b"\n", 1)
+                line = line.decode("utf-8", "replace")
+                if re.match(regexp, line):
+                    callback(line)
+        runner.qemu.on_output.append(handle_output)
+    return setup_call_on_line
+
+def stop_on_line(regexp):
+    """Returns a monitor that stops when QEMU prints a line matching
+    'regexp'."""
+
+    def stop(line):
+        raise TerminateTest
+    return call_on_line(regexp, stop)
+
+def shell_script(script, terminate_match=None):
+    """Returns a monitor that plays the script, and stops when the script is
+    done executing."""
+
+    def setup_call_on_line(runner):
+        class context:
+            n = 0
+            buf = bytearray()
+        def handle_output(output):
+            context.buf.extend(output)
+            if terminate_match is not None:
+                if re.match(terminate_match, context.buf.decode('utf-8', 'replace')):
+                    raise TerminateTest
+            if b'$ ' in context.buf:
+                context.buf = bytearray()
+                if context.n < len(script):
+                    runner.qemu.write(script[context.n])
+                    runner.qemu.write('\n')
+                    context.n += 1
+                else:
+                    if terminate_match is None:
+                        raise TerminateTest
+        runner.qemu.on_output.append(handle_output)
+    return setup_call_on_line

time.txt

@@ -0,0 +1 @@
+6

user/find.c

@@ -0,0 +1,74 @@
+#include "kernel/types.h"
+#include "user/user.h"
+#include "kernel/stat.h"
+#include "kernel/fs.h"
+
+int fmtname(const char *path) {
+  int p;
+  for(p=strlen(path); p >= 0 && *(path + p) != '/'; p--);
+  p++;
+  return p;
+}
+
+void find(const char *path, const char* target) {
+    char buf[512], *p;
+    int fd;
+    struct dirent de;
+    struct stat st;
+    if((fd = open(path, 0)) < 0){
+        fprintf(2, "find: cannot open %s\n", path);
+        return;
+    }
+
+    if(fstat(fd, &st) < 0){
+        fprintf(2, "find: cannot stat %s\n", path);
+        close(fd);
+        return;
+    }
+
+    switch(st.type){
+    case T_DEVICE:
+    case T_FILE:
+        if (strcmp(path + fmtname(path), target) == 0) {
+            printf("%s\n", path);
+        }
+        break;
+
+    case T_DIR:
+        if (strcmp(path + fmtname(path), target) == 0) {
+            printf("%s\n", path);
+        }
+        if(strlen(path) + 1 + DIRSIZ + 1 > sizeof buf){
+            printf("find: path too long\n");
+            break;
+        }
+        strcpy(buf, path);
+        p = buf+strlen(buf);
+        *p++ = '/';
+        while(read(fd, &de, sizeof(de)) == sizeof(de)){
+            if(de.inum == 0)
+                continue;
+            if (strcmp(de.name, ".") == 0 || strcmp(de.name, "..") == 0)
+                continue;
+            memmove(p, de.name, DIRSIZ);
+            p[DIRSIZ] = 0;
+            if(stat(buf, &st) < 0){
+                printf("find: cannot stat %s\n", buf);
+                continue;
+            }
+            find(buf, target);
+        }
+        break;
+    }
+    close(fd);
+}
+
+int main(int argc, char** argv) {
+    if (argc != 3) {
+        printf("\x1b[31mInvalid arguments\x1b[0m\n");
+        printf("\x1b[32musage\x1b[0m: find <base directory> <file name to find>\n");
+        exit(0);
+    }
+    find(argv[1], argv[2]);
+    exit(0);
+}

user/pingpong.c

@@ -0,0 +1,27 @@
+#include "kernel/types.h"
+#include "user/user.h"
+
+int main(int argc, char** argv) {
+    int p[2]; // hell, read from p[0] and write to p[1] no matter in pa/ch
+    if (pipe(p) == -1) exit(1);
+    uint8 senddata[] = {0xAC};
+    uint8 recvdata[] = {0};
+    int pid = fork();
+    if (pid == 0) {
+        // child
+        if (read(p[0], recvdata, 1) != 1) printf("error child read\n");
+        close(p[0]);
+        printf("%d: received ping\n", getpid());
+        if (write(p[1], senddata, 1) != 1) printf("error child write\n");
+        close(p[1]);
+        exit(0);
+    }
+    else {
+        if (write(p[1], senddata, 1) != 1) printf("error parent write\n");
+        close(p[1]);
+        if (read(p[0], recvdata, 1) != 1) printf("error parent read\n");
+        printf("%d: received pong\n", getpid());
+        close(p[0]);
+        exit(0);
+    }
+}

user/primes.c

@@ -0,0 +1,51 @@
+#include "kernel/types.h"
+#include "user/user.h"
+
+void pipeline(int leftfd) {
+    int pipefd[2];
+    int p; read(leftfd, &p, sizeof(p));
+    printf("prime %d\n", p);
+    int n; 
+    int has_right = 0;
+    while (read(leftfd, &n, sizeof(n)) > 0) {
+        if (n % p != 0) {
+            if (!has_right) {
+                has_right = 1;
+                pipe(pipefd);
+                if (fork() == 0) {
+                    close(pipefd[1]);
+                    pipeline(pipefd[0]);
+                } else {
+                    close(pipefd[0]);
+                }
+            }
+            write(pipefd[1], &n, sizeof(n));
+        }
+    }
+    close(leftfd);
+    if (has_right) {
+        close(pipefd[1]);
+        while(wait(0) != -1);
+    }
+    exit(0);
+}
+
+int main(int argc, char** argv) {
+    int pipefd[2];
+    pipe(pipefd);
+    int pid = fork();
+    if (pid != 0) {
+        close(pipefd[0]); // no need to read in the feeding proc
+        for (int i = 2; i <= 35; ++ i) {
+            write(pipefd[1], &i, sizeof(i));
+        }
+        close(pipefd[1]);
+        while(wait(0) != -1);
+        exit(0);
+    }
+    else {
+        close(pipefd[1]);  // pipeline proc will have its own write pipe
+        pipeline(pipefd[0]);
+    }
+    exit(0);
+}

user/sleep.c

@@ -0,0 +1,17 @@
+#include "kernel/types.h"
+#include "user/user.h"
+
+int main(int argc, char** argv) {
+    if (argc != 2) {
+        printf("\x1b[31mUnexpected argument\x1b[0m\n");
+        printf("usage: sleep <ticks>\n");
+        exit(0);
+    }
+    int ticks = atoi(argv[1]);
+    int ret = sleep(ticks);
+    if (ret) {
+        printf("\x1b[31mFailed to sleep\x1b[0m\n");
+        exit(-1);
+    }
+    exit(0);
+}

user/xargs.c

@@ -0,0 +1,59 @@
+#include "kernel/param.h"
+#include "kernel/types.h"
+#include "user/user.h"
+
+static inline int is_ws(const char ch) {
+    return ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r';
+}
+
+int main(int argc, char** argv) {
+    int STDIN = 0;
+    char linebuf[1024];
+    char* p = linebuf;
+    char* _argv[MAXARG];
+    while (read(STDIN, p, 1) > 0) {
+        if (*p == '\n') {
+            int i;
+            int in_ws = 1;
+            for (i = 0; i < argc - 1; ++i) {
+                _argv[i] = argv[i + 1];
+            }
+            for (char* p0 = linebuf; p0 <= p; ++p0) {
+                if (is_ws(*p0)) {
+                    if (!in_ws) {
+                        in_ws = 1;
+                        i++;
+                    }
+                    *p0 = '\0';
+                } else if (in_ws) {
+                    in_ws = 0;
+                    _argv[i] = p0;
+                }
+                if (i >= MAXARG) {
+                    printf("warning: too many arguments");
+                    break;
+                }
+            }
+            *p = '\0';
+            _argv[i] = 0;
+            // for (int j = 0; j < i; ++ j) {
+            //     printf("%s\n", _argv[j]);
+            // }
+            if (fork() == 0) {
+                exec(_argv[0], _argv);
+                exit(0);
+            } else {
+                p = linebuf;
+                while (wait(0) != -1)
+                    ;
+            }
+        } else {
+            p++;
+            if (p >= linebuf + sizeof(linebuf)) {
+                printf("line buffer exceeded\n");
+                exit(0);
+            }
+        }
+    }
+    exit(0);
+}

user/xargstest.sh

@@ -0,0 +1,6 @@
+mkdir a
+echo hello > a/b
+mkdir c
+echo hello > c/b
+echo hello > b
+find . b | xargs grep hello