lab util grade 100

Makefile

@@ -188,6 +188,11 @@ UPROGS=\
 	$U/_grind\
 	$U/_wc\
 	$U/_zombie\
+	$U/_sleep\
+	$U/_pingpong\
+	$U/_primes\
+	$U/_find\
+	$U/_xargs\
 
 
 

README

@@ -6,7 +6,7 @@ ACKNOWLEDGMENTS
 
 xv6 is inspired by John Lions's Commentary on UNIX 6th Edition (Peer
 to Peer Communications; ISBN: 1-57398-013-7; 1st edition (June 14,
-2000)).  See also https://pdos.csail.mit.edu/6.1810/, which provides
+2000)).  See also https://pdos.csail.mit.edu/6.828/, which provides
 pointers to on-line resources for v6.
 
 The following people have made contributions: Russ Cox (context switching,
@@ -14,31 +14,29 @@ locking), Cliff Frey (MP), Xiao Yu (MP), Nickolai Zeldovich, and Austin
 Clements.
 
 We are also grateful for the bug reports and patches contributed by
-Takahiro Aoyagi, Silas Boyd-Wickizer, Anton Burtsev, carlclone, Ian
-Chen, Dan Cross, Cody Cutler, Mike CAT, Tej Chajed, Asami Doi,
-eyalz800, Nelson Elhage, Saar Ettinger, Alice Ferrazzi, Nathaniel
-Filardo, flespark, Peter Froehlich, Yakir Goaron, Shivam Handa, Matt
-Harvey, Bryan Henry, jaichenhengjie, Jim Huang, Matúš Jókay, John
-Jolly, Alexander Kapshuk, Anders Kaseorg, kehao95, Wolfgang Keller,
-Jungwoo Kim, Jonathan Kimmitt, Eddie Kohler, Vadim Kolontsov, Austin
-Liew, l0stman, Pavan Maddamsetti, Imbar Marinescu, Yandong Mao, Matan
-Shabtay, Hitoshi Mitake, Carmi Merimovich, Mark Morrissey, mtasm, Joel
-Nider, Hayato Ohhashi, OptimisticSide, Harry Porter, Greg Price, Jude
-Rich, segfault, Ayan Shafqat, Eldar Sehayek, Yongming Shen, Fumiya
-Shigemitsu, Cam Tenny, tyfkda, Warren Toomey, Stephen Tu, Rafael Ubal,
-Amane Uehara, Pablo Ventura, Xi Wang, WaheedHafez, Keiichi Watanabe,
-Nicolas Wolovick, wxdao, Grant Wu, Jindong Zhang, Icenowy Zheng,
-ZhUyU1997, and Zou Chang Wei.
-
+Takahiro Aoyagi, Silas Boyd-Wickizer, Anton Burtsev, Ian Chen, Dan
+Cross, Cody Cutler, Mike CAT, Tej Chajed, Asami Doi, eyalz800, Nelson
+Elhage, Saar Ettinger, Alice Ferrazzi, Nathaniel Filardo, flespark,
+Peter Froehlich, Yakir Goaron, Shivam Handa, Matt Harvey, Bryan Henry,
+jaichenhengjie, Jim Huang, Matúš Jókay, Alexander Kapshuk, Anders
+Kaseorg, kehao95, Wolfgang Keller, Jungwoo Kim, Jonathan Kimmitt,
+Eddie Kohler, Vadim Kolontsov, Austin Liew, l0stman, Pavan
+Maddamsetti, Imbar Marinescu, Yandong Mao, Matan Shabtay, Hitoshi
+Mitake, Carmi Merimovich, Mark Morrissey, mtasm, Joel Nider,
+OptimisticSide, Greg Price, Jude Rich, Ayan Shafqat, Eldar Sehayek,
+Yongming Shen, Fumiya Shigemitsu, Cam Tenny, tyfkda, Warren Toomey,
+Stephen Tu, Rafael Ubal, Amane Uehara, Pablo Ventura, Xi Wang, Keiichi
+Watanabe, Nicolas Wolovick, wxdao, Grant Wu, Jindong Zhang, Icenowy
+Zheng, ZhUyU1997, and Zou Chang Wei.
 
 The code in the files that constitute xv6 is
-Copyright 2006-2022 Frans Kaashoek, Robert Morris, and Russ Cox.
+Copyright 2006-2020 Frans Kaashoek, Robert Morris, and Russ Cox.
 
 ERROR REPORTS
 
 Please send errors and suggestions to Frans Kaashoek and Robert Morris
 (kaashoek,rtm@mit.edu).  The main purpose of xv6 is as a teaching
-operating system for MIT's 6.1810, so we are more interested in
+operating system for MIT's 6.S081, so we are more interested in
 simplifications and clarifications than new features.
 
 BUILDING AND RUNNING XV6

answers-pgtbl.txt

@@ -1,8 +0,0 @@
-Q: Which other xv6 system call(s) could be made faster using this shared page? Explain how.
-A:  sys_uptime. Make the global tick in a user access page, and map the address of tick into usyscall.
-
-Q: Explain the output of vmprint in terms of Fig 3-4 from the text. What does page 0 contain? What is in page 2? When running in user mode, could the process read/write the memory mapped by page 1? What does the third to last page contain?
-A:  Page 0 contains process's text (code). 
-    Page 2 is the guard page.
-    Page 1 could be read and write in user mode, due to its PTE_U(1 << 4), PTE_R(1 << 2) and PTE_W(1 << 3) flags being set.
-    The third to last page, aka page 255-511-509, is the usyscall page used in the last task.

conf/lab.mk

@@ -1 +1 @@
-LAB=pgtbl
+LAB=util

grade-lab-pgtbl

@@ -1,78 +0,0 @@
-#!/usr/bin/env python3
-
-import re
-from gradelib import *
-
-r = Runner(save("xv6.out"))
-
-PTE_PRINT = """page table 0x0000000087f6e000
- ..0: pte 0x0000000021fda801 pa 0x0000000087f6a000
- .. ..0: pte 0x0000000021fda401 pa 0x0000000087f69000
- .. .. ..0: pte 0x0000000021fdac1f pa 0x0000000087f6b000
- .. .. ..1: pte 0x0000000021fda00f pa 0x0000000087f68000
- .. .. ..2: pte 0x0000000021fd9c1f pa 0x0000000087f67000
- ..255: pte 0x0000000021fdb401 pa 0x0000000087f6d000
- .. ..511: pte 0x0000000021fdb001 pa 0x0000000087f6c000
- .. .. ..509: pte 0x0000000021fdd813 pa 0x0000000087f76000
- .. .. ..510: pte 0x0000000021fddc07 pa 0x0000000087f77000
- .. .. ..511: pte 0x0000000020001c0b pa 0x0000000080007000"""
-
-VAL_RE = "(0x00000000[0-9a-f]+)"
-INDENT_RE = r"\s*\.\.\s*"
-INDENT_ESC = "\\\s*\.\.\\\s*"
-
-@test(0, "pgtbltest")
-def test_pgtbltest():
-    r.run_qemu(shell_script([
-        'pgtbltest'
-    ]), timeout=300)
-
-@test(10, "pgtbltest: ugetpid", parent=test_pgtbltest)
-def test_nettest_():
-    r.match('^ugetpid_test: OK$')
-
-@test(10, "pgtbltest: pgaccess", parent=test_pgtbltest)
-def test_nettest_():
-    r.match('^pgaccess_test: OK$')
-
-@test(10, "pte printout")
-def test_pteprint():
-    first = True
-    r.run_qemu(shell_script([
-        'echo hi'
-    ]))
-    r.match('^hi')
-    p = re.compile(VAL_RE)
-    d = re.compile(INDENT_RE)
-    for l in PTE_PRINT.splitlines():
-        l = d.sub(INDENT_ESC, l)
-        l = p.sub(VAL_RE, l)
-        r.match(r'^{}$'.format(l))
-        if first:
-            first = False
-        else:
-            matches = re.findall(r'^{}$'.format(l), r.qemu.output, re.MULTILINE)
-            assert_equal(len(matches[0]), 2)
-            pa = (int(matches[0][0], 16) >> 10) << 12
-            assert_equal(int(matches[0][1], 16), pa)
-
-@test(5, "answers-pgtbl.txt")
-def test_answers():
-    # just a simple sanity check, will be graded manually
-    check_answers("answers-pgtbl.txt")
-
-@test(0, "usertests")
-def test_usertests():
-    r.run_qemu(shell_script([
-        'usertests -q'
-    ]), timeout=300)
-
-@test(10, "usertests: all tests", parent=test_usertests)
-def test_usertests():
-    r.match('^ALL TESTS PASSED$')
-
-@test(1, "time")
-def test_time():
-    check_time()
-
-run_tests()

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()

kernel/defs.h

@@ -173,7 +173,6 @@ uint64          walkaddr(pagetable_t, uint64);
 int             copyout(pagetable_t, uint64, char *, uint64);
 int             copyin(pagetable_t, char *, uint64, uint64);
 int             copyinstr(pagetable_t, char *, uint64, uint64);
-void            vmprint(pagetable_t pagetable);
 
 // plic.c
 void            plicinit(void);

kernel/exec.c

@@ -128,7 +128,6 @@ exec(char *path, char **argv)
   p->trapframe->sp = sp; // initial stack pointer
   proc_freepagetable(oldpagetable, oldsz);
 
-  if (p->pid == 1) vmprint(p->pagetable);
   return argc; // this ends up in a0, the first argument to main(argc, argv)
 
  bad:

kernel/memlayout.h

@@ -25,10 +25,6 @@
 #define VIRTIO0 0x10001000
 #define VIRTIO0_IRQ 1
 
-#ifdef LAB_NET
-#define E1000_IRQ 33
-#endif
-
 // core local interruptor (CLINT), which contains the timer.
 #define CLINT 0x2000000L
 #define CLINT_MTIMECMP(hartid) (CLINT + 0x4000 + 8*(hartid))
@@ -57,7 +53,7 @@
 
 // map kernel stacks beneath the trampoline,
 // each surrounded by invalid guard pages.
-#define KSTACK(p) (TRAMPOLINE - (p)*2*PGSIZE - 3*PGSIZE)
+#define KSTACK(p) (TRAMPOLINE - ((p)+1)* 2*PGSIZE)
 
 // User memory layout.
 // Address zero first:
@@ -66,14 +62,6 @@
 //   fixed-size stack
 //   expandable heap
 //   ...
-//   USYSCALL (shared with kernel)
 //   TRAPFRAME (p->trapframe, used by the trampoline)
 //   TRAMPOLINE (the same page as in the kernel)
 #define TRAPFRAME (TRAMPOLINE - PGSIZE)
-#ifdef LAB_PGTBL
-#define USYSCALL (TRAPFRAME - PGSIZE)
-
-struct usyscall {
-  int pid;  // Process ID
-};
-#endif

kernel/proc.c

@@ -131,11 +131,6 @@ found:
     release(&p->lock);
     return 0;
   }
-  if ((p->usyscall_page = (uint64)kalloc()) == 0) {
-    freeproc(p);
-    release(&p->lock);
-    return 0;
-  }
 
   // An empty user page table.
   p->pagetable = proc_pagetable(p);
@@ -144,8 +139,7 @@ found:
     release(&p->lock);
     return 0;
   }
-  struct usyscall* usyscall_ptr = (struct usyscall*)p->usyscall_page;
-  usyscall_ptr->pid = p->pid;
+
   // Set up new context to start executing at forkret,
   // which returns to user space.
   memset(&p->context, 0, sizeof(p->context));
@@ -164,9 +158,6 @@ freeproc(struct proc *p)
   if(p->trapframe)
     kfree((void*)p->trapframe);
   p->trapframe = 0;
-  if(p->usyscall_page)
-    kfree((void*)p->usyscall_page);
-  p->usyscall_page = 0;
   if(p->pagetable)
     proc_freepagetable(p->pagetable, p->sz);
   p->pagetable = 0;
@@ -211,14 +202,6 @@ proc_pagetable(struct proc *p)
     return 0;
   }
 
-  if (mappages(pagetable, USYSCALL, PGSIZE,
-                p->usyscall_page, PTE_U | PTE_R) < 0)
-  {
-    uvmunmap(pagetable, USYSCALL, 1, 0);
-    uvmfree(pagetable, 0);
-    return 0;
-  }
-
   return pagetable;
 }
 
@@ -229,7 +212,6 @@ proc_freepagetable(pagetable_t pagetable, uint64 sz)
 {
   uvmunmap(pagetable, TRAMPOLINE, 1, 0);
   uvmunmap(pagetable, TRAPFRAME, 1, 0);
-  uvmunmap(pagetable, USYSCALL, 1, 0);
   uvmfree(pagetable, sz);
 }
 

kernel/proc.h

@@ -99,7 +99,6 @@ struct proc {
   uint64 kstack;               // Virtual address of kernel stack
   uint64 sz;                   // Size of process memory (bytes)
   pagetable_t pagetable;       // User page table
-  uint64 usyscall_page;        // USYSCALL page phy addr
   struct trapframe *trapframe; // data page for trampoline.S
   struct context context;      // swtch() here to run process
   struct file *ofile[NOFILE];  // Open files

kernel/riscv.h

@@ -343,7 +343,6 @@ typedef uint64 *pagetable_t; // 512 PTEs
 #define PTE_W (1L << 2)
 #define PTE_X (1L << 3)
 #define PTE_U (1L << 4) // user can access
-#define PTE_A (1L << 6)
 
 // shift a physical address to the right place for a PTE.
 #define PA2PTE(pa) ((((uint64)pa) >> 12) << 10)

kernel/syscall.c

@@ -102,13 +102,6 @@ extern uint64 sys_link(void);
 extern uint64 sys_mkdir(void);
 extern uint64 sys_close(void);
 
-#ifdef LAB_NET
-extern uint64 sys_connect(void);
-#endif
-#ifdef LAB_PGTBL
-extern uint64 sys_pgaccess(void);
-#endif
-
 // An array mapping syscall numbers from syscall.h
 // to the function that handles the system call.
 static uint64 (*syscalls[])(void) = {
@@ -133,16 +126,8 @@ static uint64 (*syscalls[])(void) = {
 [SYS_link]    sys_link,
 [SYS_mkdir]   sys_mkdir,
 [SYS_close]   sys_close,
-#ifdef LAB_NET
-[SYS_connect] sys_connect,
-#endif
-#ifdef LAB_PGTBL
-[SYS_pgaccess] sys_pgaccess,
-#endif
 };
 
-
-
 void
 syscall(void)
 {

kernel/syscall.h

@@ -20,14 +20,3 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
-
-// System calls for labs
-#define SYS_trace     22
-#define SYS_sysinfo   23
-#define SYS_sigalarm  24
-#define SYS_sigreturn 25
-#define SYS_symlink   26
-#define SYS_mmap      27
-#define SYS_munmap    28
-#define SYS_connect   29
-#define SYS_pgaccess  30

kernel/sysproc.c

@@ -1,7 +1,7 @@
 #include "types.h"
 #include "riscv.h"
-#include "param.h"
 #include "defs.h"
+#include "param.h"
 #include "memlayout.h"
 #include "spinlock.h"
 #include "proc.h"
@@ -54,7 +54,6 @@ sys_sleep(void)
   int n;
   uint ticks0;
 
-
   argint(0, &n);
   acquire(&tickslock);
   ticks0 = ticks;
@@ -69,35 +68,6 @@ sys_sleep(void)
   return 0;
 }
 
-
-#ifdef LAB_PGTBL
-#define MAX_ABITS (64)
-
-int
-sys_pgaccess(void)
-{
-  char access_bits[MAX_ABITS / 8] = {0};
-  uint64 base;
-  int pages;
-  uint64 mask;
-  argaddr(0, &base); // void*
-  argint(1, &pages); // int
-  argaddr(2, &mask); // void*
-  if (pages > MAX_ABITS) return -1;
-  acquire(&myproc()->lock);
-  for (int page = 0; page < pages; ++ page) {
-    pte_t* pte = walk(myproc()->pagetable, base + (page << PGSHIFT), 0);
-    if (*pte & PTE_A) {
-      *pte &= ~PTE_A;
-      access_bits[page / 8] |= 1 << (page & 0x7);
-    }
-  }
-  release(&myproc()->lock);
-  copyout(myproc()->pagetable, mask, access_bits, (pages & 0x7) ? (pages >> 3) + 1 : (pages >> 3));
-  return 0;
-}
-#endif
-
 uint64
 sys_kill(void)
 {

kernel/vm.c

@@ -437,28 +437,3 @@ copyinstr(pagetable_t pagetable, char *dst, uint64 srcva, uint64 max)
     return -1;
   }
 }
-
-static void _vmprint(pagetable_t pagetable, int depth)
-{
-  if (depth == 3)
-    return;
-  for (int i = 0; i < 512; ++i)
-  {
-    pte_t pte = pagetable[i];
-    if (pte & PTE_V)
-    {
-      for (int _i = 0; _i < depth; ++_i)
-      {
-        printf(".. ");
-      }
-      printf("..%d: pte %p pa %p\n", i, pte, PTE2PA(pte));
-      _vmprint((pagetable_t)PTE2PA(pte), depth + 1);
-    }
-  }
-}
-
-void vmprint(pagetable_t pagetable)
-{
-  printf("page table %p\n", pagetable);
-  _vmprint(pagetable, 0);
-}

time.txt

@@ -1 +1 @@
-4
+6

user/cat.c

@@ -1,6 +1,5 @@
 #include "kernel/types.h"
 #include "kernel/stat.h"
-#include "kernel/fcntl.h"
 #include "user/user.h"
 
 char buf[512];
@@ -33,7 +32,7 @@ main(int argc, char *argv[])
   }
 
   for(i = 1; i < argc; i++){
-    if((fd = open(argv[i], O_RDONLY)) < 0){
+    if((fd = open(argv[i], 0)) < 0){
       fprintf(2, "cat: cannot open %s\n", argv[i]);
       exit(1);
     }

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/grep.c

@@ -2,7 +2,6 @@
 
 #include "kernel/types.h"
 #include "kernel/stat.h"
-#include "kernel/fcntl.h"
 #include "user/user.h"
 
 char buf[1024];
@@ -52,7 +51,7 @@ main(int argc, char *argv[])
   }
 
   for(i = 2; i < argc; i++){
-    if((fd = open(argv[i], O_RDONLY)) < 0){
+    if((fd = open(argv[i], 0)) < 0){
       printf("grep: cannot open %s\n", argv[i]);
       exit(1);
     }

user/ls.c

@@ -2,7 +2,6 @@
 #include "kernel/stat.h"
 #include "user/user.h"
 #include "kernel/fs.h"
-#include "kernel/fcntl.h"
 
 char*
 fmtname(char *path)
@@ -31,7 +30,7 @@ ls(char *path)
   struct dirent de;
   struct stat st;
 
-  if((fd = open(path, O_RDONLY)) < 0){
+  if((fd = open(path, 0)) < 0){
     fprintf(2, "ls: cannot open %s\n", path);
     return;
   }

user/pgtbltest.c

@@ -1,70 +0,0 @@
-#include "kernel/param.h"
-#include "kernel/fcntl.h"
-#include "kernel/types.h"
-#include "kernel/riscv.h"
-#include "user/user.h"
-
-void ugetpid_test();
-void pgaccess_test();
-
-int
-main(int argc, char *argv[])
-{
-  ugetpid_test();
-  pgaccess_test();
-  printf("pgtbltest: all tests succeeded\n");
-  exit(0);
-}
-
-char *testname = "???";
-
-void
-err(char *why)
-{
-  printf("pgtbltest: %s failed: %s, pid=%d\n", testname, why, getpid());
-  exit(1);
-}
-
-void
-ugetpid_test()
-{
-  int i;
-
-  printf("ugetpid_test starting\n");
-  testname = "ugetpid_test";
-
-  for (i = 0; i < 64; i++) {
-    int ret = fork();
-    if (ret != 0) {
-      wait(&ret);
-      if (ret != 0)
-        exit(1);
-      continue;
-    }
-    if (getpid() != ugetpid())
-      err("missmatched PID");
-    exit(0);
-  }
-  printf("ugetpid_test: OK\n");
-}
-
-void
-pgaccess_test()
-{
-  char *buf;
-  unsigned int abits;
-  printf("pgaccess_test starting\n");
-  testname = "pgaccess_test";
-  buf = malloc(32 * PGSIZE);
-  if (pgaccess(buf, 32, &abits) < 0)
-    err("pgaccess failed");
-  buf[PGSIZE * 1] += 1;
-  buf[PGSIZE * 2] += 1;
-  buf[PGSIZE * 30] += 1;
-  if (pgaccess(buf, 32, &abits) < 0)
-    err("pgaccess failed");
-  if (abits != ((1 << 1) | (1 << 2) | (1 << 30)))
-    err("incorrect access bits set");
-  free(buf);
-  printf("pgaccess_test: OK\n");
-}

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/ulib.c

@@ -1,13 +1,8 @@
 #include "kernel/types.h"
 #include "kernel/stat.h"
 #include "kernel/fcntl.h"
-#ifdef LAB_PGTBL
-#include "kernel/riscv.h"
-#include "kernel/memlayout.h"
-#endif
 #include "user/user.h"
 
-
 //
 // wrapper so that it's OK if main() does not call exit().
 //
@@ -150,12 +145,3 @@ memcpy(void *dst, const void *src, uint n)
 {
   return memmove(dst, src, n);
 }
-
-#ifdef LAB_PGTBL
-int
-ugetpid(void)
-{
-  struct usyscall *u = (struct usyscall *)USYSCALL;
-  return u->pid;
-}
-#endif

user/user.h

@@ -22,14 +22,6 @@ int getpid(void);
 char* sbrk(int);
 int sleep(int);
 int uptime(void);
-#ifdef LAB_NET
-int connect(uint32, uint16, uint16);
-#endif
-#ifdef LAB_PGTBL
-int pgaccess(void *base, int len, void *mask);
-// usyscall region
-int ugetpid(void);
-#endif
 
 // ulib.c
 int stat(const char*, struct stat*);
@@ -47,4 +39,3 @@ void free(void*);
 int atoi(const char*);
 int memcmp(const void *, const void *, uint);
 void *memcpy(void *, const void *, uint);
-int statistics(void*, int);

user/usys.pl

@@ -36,5 +36,3 @@ entry("getpid");
 entry("sbrk");
 entry("sleep");
 entry("uptime");
-entry("connect");
-entry("pgaccess");

user/wc.c

@@ -1,6 +1,5 @@
 #include "kernel/types.h"
 #include "kernel/stat.h"
-#include "kernel/fcntl.h"
 #include "user/user.h"
 
 char buf[512];
@@ -44,7 +43,7 @@ main(int argc, char *argv[])
   }
 
   for(i = 1; i < argc; i++){
-    if((fd = open(argv[i], O_RDONLY)) < 0){
+    if((fd = open(argv[i], 0)) < 0){
       printf("wc: cannot open %s\n", argv[i]);
       exit(1);
     }

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