lab util grade 100

Makefile

@@ -188,8 +188,11 @@ UPROGS=\
 	$U/_grind\
 	$U/_wc\
 	$U/_zombie\
-	$U/_trace\
-	$U/_sysinfotest\
+	$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-syscall.txt

@@ -1,17 +0,0 @@
-Q: Looking at the backtrace output, which function called syscall?
-A: usertrap
-
-Q: What is the value of p->trapframe->a7 and what does that value represent?
-A: a7 is 0x7. It represents the number of syscall SYS_exec.
-
-Q: What was the previous mode that the CPU was in?
-A: $sstatus is now 0x22, which is 0b0000_0010_0010, with SPP(bit-8) 0, so its previous privilege is User Mode.
-
-Q: Write down the assembly instruction the kernel is panicing at. Which register corresponds to the varialable num?
-A: The kernel is panicing at instruct `lw a3,0(zero)` at 0x80001ff6. The register corresponding to the variable num is a3.
-
-Q: Why does the kernel crash? Hint: look at figure 3-3 in the text; is address 0 mapped in the kernel address space? Is that confirmed by the value in scause above? 
-A: $scause is 0xd(13) which corresponds to 'Load page fault'. According to figure 3-3, this address is not mapped in the kernel address space, so this causes page fault.
-
-Q: What is the name of the binary that was running when the kernel paniced? What is its process id (pid)?
-A: The name of the binary is "initcode", and its pid is 1.

conf/lab.mk

@@ -1 +1 @@
-LAB=syscall
+LAB=util

grade-lab-syscall

@@ -1,69 +0,0 @@
-#!/usr/bin/env python3
-
-import re
-from gradelib import *
-
-r = Runner(save("xv6.out"))
-
-@test(5, "answers-syscall.txt")
-def test_answers():
-    # just a simple sanity check, will be graded manually
-    check_answers("answers-syscall.txt")
-
-@test(5, "trace 32 grep")
-def test_trace_32_grep():
-    r.run_qemu(shell_script([
-        'trace 32 grep hello README'
-    ]))
-    r.match('^\\d+: syscall read -> 1023')
-    r.match('^\\d+: syscall read -> 961')
-    r.match('^\\d+: syscall read -> 321')
-    r.match('^\\d+: syscall read -> 0')
-
-@test(5, "trace all grep")
-def test_trace_all_grep():
-    r.run_qemu(shell_script([
-        'trace 2147483647 grep hello README'
-    ]))
-    r.match('^\\d+: syscall trace -> 0')
-    r.match('^\\d+: syscall exec -> 3')
-    r.match('^\\d+: syscall open -> 3')
-    r.match('^\\d+: syscall read -> 1023')
-    r.match('^\\d+: syscall read -> 961')
-    r.match('^\\d+: syscall read -> 321')
-    r.match('^\\d+: syscall read -> 0')
-    r.match('^\\d+: syscall close -> 0')
-
-@test(5, "trace nothing")
-def test_trace_nothing():
-    r.run_qemu(shell_script([
-        'grep hello README'
-    ]))
-    r.match(no=[".* syscall .*"])
-
-@test(5, "trace children")
-def test_trace_children():
-    r.run_qemu(shell_script([
-        'trace 2 usertests forkforkfork'
-    ]))
-    r.match('3: syscall fork -> 4')
-    r.match('^5: syscall fork -> \\d+')
-    r.match('^6: syscall fork -> \\d+')
-    r.match('^\\d+: syscall fork -> -1')
-    r.match('^ALL TESTS PASSED')
-
-@test(14, "sysinfotest")
-def test_sysinfotest():
-    r.run_qemu(shell_script([
-        'sysinfotest'
-    ]))
-    r.match('^sysinfotest: OK', no=[".* FAIL .*"])
-
-@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

@@ -63,7 +63,6 @@ void            ramdiskrw(struct buf*);
 void*           kalloc(void);
 void            kfree(void *);
 void            kinit(void);
-int             size_of_freemem(void);
 
 // log.c
 void            initlog(int, struct superblock*);
@@ -107,7 +106,6 @@ void            yield(void);
 int             either_copyout(int user_dst, uint64 dst, void *src, uint64 len);
 int             either_copyin(void *dst, int user_src, uint64 src, uint64 len);
 void            procdump(void);
-int             number_of_process(void);
 
 // swtch.S
 void            swtch(struct context*, struct context*);

kernel/kalloc.c

@@ -80,18 +80,3 @@ kalloc(void)
     memset((char*)r, 5, PGSIZE); // fill with junk
   return (void*)r;
 }
-
-int
-size_of_freemem(void)
-{
-  struct run *r;
-  int count = 0;
-  acquire(&kmem.lock);
-  r = kmem.freelist;
-  while (r) {
-    count ++;
-    r = r->next;
-  }
-  release(&kmem.lock);
-  return count * PGSIZE;
-}

kernel/proc.c

@@ -311,7 +311,7 @@ fork(void)
   safestrcpy(np->name, p->name, sizeof(p->name));
 
   pid = np->pid;
-  np->tracemask = p->tracemask;
+
   release(&np->lock);
 
   acquire(&wait_lock);
@@ -681,14 +681,3 @@ procdump(void)
     printf("\n");
   }
 }
-
-int
-number_of_process(void)
-{
-  struct proc *p;
-  int count = 0;
-  for (p = proc; p < &proc[NPROC]; p ++) {
-    if (p->state != UNUSED) count ++;
-  }
-  return count;
-}

kernel/proc.h

@@ -104,5 +104,4 @@ struct proc {
   struct file *ofile[NOFILE];  // Open files
   struct inode *cwd;           // Current directory
   char name[16];               // Process name (debugging)
-  int tracemask;               // mask for syscall trace
 };

kernel/syscall.c

@@ -101,8 +101,6 @@ extern uint64 sys_unlink(void);
 extern uint64 sys_link(void);
 extern uint64 sys_mkdir(void);
 extern uint64 sys_close(void);
-extern uint64 sys_trace(void);
-extern uint64 sys_sysinfo(void);
 
 // An array mapping syscall numbers from syscall.h
 // to the function that handles the system call.
@@ -128,33 +126,6 @@ static uint64 (*syscalls[])(void) = {
 [SYS_link]    sys_link,
 [SYS_mkdir]   sys_mkdir,
 [SYS_close]   sys_close,
-[SYS_trace]   sys_trace,
-[SYS_sysinfo] sys_sysinfo,
-};
-
-char syscall_name[][8] = {
-[SYS_fork]    "fork",
-[SYS_exit]    "exit",
-[SYS_wait]    "wait",
-[SYS_pipe]    "pipe",
-[SYS_read]    "read",
-[SYS_kill]    "kill",
-[SYS_exec]    "exec",
-[SYS_fstat]   "fstat",
-[SYS_chdir]   "chdir",
-[SYS_dup]     "dup",
-[SYS_getpid]  "getpid",
-[SYS_sbrk]    "sbrk",
-[SYS_sleep]   "sleep",
-[SYS_uptime]  "uptime",
-[SYS_open]    "open",
-[SYS_write]   "write",
-[SYS_mknod]   "mknod",
-[SYS_unlink]  "unlink",
-[SYS_link]    "link",
-[SYS_mkdir]   "mkdir",
-[SYS_close]   "close",
-[SYS_trace]   "trace",
 };
 
 void
@@ -168,8 +139,6 @@ syscall(void)
     // Use num to lookup the system call function for num, call it,
     // and store its return value in p->trapframe->a0
     p->trapframe->a0 = syscalls[num]();
-    if ((1 << num) & p->tracemask)
-      printf("%d: syscall %s -> %d\n", p->pid, syscall_name[num], p->trapframe->a0);
   } else {
     printf("%d %s: unknown sys call %d\n",
             p->pid, p->name, num);

kernel/syscall.h

@@ -20,5 +20,3 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
-#define SYS_trace  22
-#define SYS_sysinfo 23

kernel/sysinfo.h

@@ -1,4 +0,0 @@
-struct sysinfo {
-  uint64 freemem;   // amount of free memory (bytes)
-  uint64 nproc;     // number of process
-};

kernel/sysproc.c

@@ -5,7 +5,6 @@
 #include "memlayout.h"
 #include "spinlock.h"
 #include "proc.h"
-#include "sysinfo.h"
 
 uint64
 sys_exit(void)
@@ -56,8 +55,6 @@ sys_sleep(void)
   uint ticks0;
 
   argint(0, &n);
-  if(n < 0)
-    n = 0;
   acquire(&tickslock);
   ticks0 = ticks;
   while(ticks - ticks0 < n){
@@ -92,31 +89,3 @@ sys_uptime(void)
   release(&tickslock);
   return xticks;
 }
-
-uint64
-sys_trace(void)
-{
-  int mask;
-  argint(0, &mask);
-  acquire(&myproc()->lock);
-  myproc()->tracemask = mask;
-  release(&myproc()->lock);
-  return 0;
-}
-
-uint64
-sys_sysinfo(void)
-{
-  struct sysinfo info;
-  uint64 addr;
-  argaddr(0, &addr);
-  info.nproc = number_of_process();
-  info.freemem = size_of_freemem();
-  acquire(&myproc()->lock);
-  if(copyout(myproc()->pagetable, addr, (char *)&info, sizeof(info)) < 0){
-    release(&myproc()->lock);
-    return -1;
-  }
-  release(&myproc()->lock);
-  return 0;
-}

time.txt

@@ -1 +1 @@
-3
+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/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/sysinfotest.c

@@ -1,153 +0,0 @@
-#include "kernel/types.h"
-#include "kernel/riscv.h"
-#include "kernel/sysinfo.h"
-#include "user/user.h"
-
-
-void
-sinfo(struct sysinfo *info) {
-  if (sysinfo(info) < 0) {
-    printf("FAIL: sysinfo failed");
-    exit(1);
-  }
-}
-
-//
-// use sbrk() to count how many free physical memory pages there are.
-//
-int
-countfree()
-{
-  uint64 sz0 = (uint64)sbrk(0);
-  struct sysinfo info;
-  int n = 0;
-
-  while(1){
-    if((uint64)sbrk(PGSIZE) == 0xffffffffffffffff){
-      break;
-    }
-    n += PGSIZE;
-  }
-  sinfo(&info);
-  if (info.freemem != 0) {
-    printf("FAIL: there is no free mem, but sysinfo.freemem=%d\n",
-      info.freemem);
-    exit(1);
-  }
-  sbrk(-((uint64)sbrk(0) - sz0));
-  return n;
-}
-
-void
-testmem() {
-  struct sysinfo info;
-  uint64 n = countfree();
-  
-  sinfo(&info);
-
-  if (info.freemem!= n) {
-    printf("FAIL: free mem %d (bytes) instead of %d\n", info.freemem, n);
-    exit(1);
-  }
-  
-  if((uint64)sbrk(PGSIZE) == 0xffffffffffffffff){
-    printf("sbrk failed");
-    exit(1);
-  }
-
-  sinfo(&info);
-    
-  if (info.freemem != n-PGSIZE) {
-    printf("FAIL: free mem %d (bytes) instead of %d\n", n-PGSIZE, info.freemem);
-    exit(1);
-  }
-  
-  if((uint64)sbrk(-PGSIZE) == 0xffffffffffffffff){
-    printf("sbrk failed");
-    exit(1);
-  }
-
-  sinfo(&info);
-    
-  if (info.freemem != n) {
-    printf("FAIL: free mem %d (bytes) instead of %d\n", n, info.freemem);
-    exit(1);
-  }
-}
-
-void
-testcall() {
-  struct sysinfo info;
-  
-  if (sysinfo(&info) < 0) {
-    printf("FAIL: sysinfo failed\n");
-    exit(1);
-  }
-
-  if (sysinfo((struct sysinfo *) 0xeaeb0b5b00002f5e) !=  0xffffffffffffffff) {
-    printf("FAIL: sysinfo succeeded with bad argument\n");
-    exit(1);
-  }
-}
-
-void testproc() {
-  struct sysinfo info;
-  uint64 nproc;
-  int status;
-  int pid;
-  
-  sinfo(&info);
-  nproc = info.nproc;
-
-  pid = fork();
-  if(pid < 0){
-    printf("sysinfotest: fork failed\n");
-    exit(1);
-  }
-  if(pid == 0){
-    sinfo(&info);
-    if(info.nproc != nproc+1) {
-      printf("sysinfotest: FAIL nproc is %d instead of %d\n", info.nproc, nproc+1);
-      exit(1);
-    }
-    exit(0);
-  }
-  wait(&status);
-  sinfo(&info);
-  if(info.nproc != nproc) {
-      printf("sysinfotest: FAIL nproc is %d instead of %d\n", info.nproc, nproc);
-      exit(1);
-  }
-}
-
-void testbad() {
-  int pid = fork();
-  int xstatus;
-  
-  if(pid < 0){
-    printf("sysinfotest: fork failed\n");
-    exit(1);
-  }
-  if(pid == 0){
-      sinfo(0x0);
-      exit(0);
-  }
-  wait(&xstatus);
-  if(xstatus == -1)  // kernel killed child?
-    exit(0);
-  else {
-    printf("sysinfotest: testbad succeeded %d\n", xstatus);
-    exit(xstatus);
-  }
-}
-
-int
-main(int argc, char *argv[])
-{
-  printf("sysinfotest: start\n");
-  testcall();
-  testmem();
-  testproc();
-  printf("sysinfotest: OK\n");
-  exit(0);
-}

user/trace.c

@@ -1,27 +0,0 @@
-#include "kernel/param.h"
-#include "kernel/types.h"
-#include "kernel/stat.h"
-#include "user/user.h"
-
-int
-main(int argc, char *argv[])
-{
-  int i;
-  char *nargv[MAXARG];
-
-  if(argc < 3 || (argv[1][0] < '0' || argv[1][0] > '9')){
-    fprintf(2, "Usage: %s mask command\n", argv[0]);
-    exit(1);
-  }
-
-  if (trace(atoi(argv[1])) < 0) {
-    fprintf(2, "%s: trace failed\n", argv[0]);
-    exit(1);
-  }
-  
-  for(i = 2; i < argc && i < MAXARG; i++){
-    nargv[i-2] = argv[i];
-  }
-  exec(nargv[0], nargv);
-  exit(0);
-}

user/user.h

@@ -1,5 +1,4 @@
 struct stat;
-struct sysinfo;
 
 // system calls
 int fork(void);
@@ -23,8 +22,6 @@ int getpid(void);
 char* sbrk(int);
 int sleep(int);
 int uptime(void);
-int trace(int);
-int sysinfo(struct sysinfo*);
 
 // ulib.c
 int stat(const char*, struct stat*);

user/usys.pl

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

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