text: #include "param.h"
  #include "types.h"
  #include "stat.h"
  #include "user.h"
  #include "fs.h"
  #include "fcntl.h"
  #include "syscall.h"
  #include "traps.h"
  #include "memlayout.h"
  
  char buf[8192];
  char name[3];
  char *echoargv[] = {"echo", "ALL", "TESTS", "PASSED", 0};
  int stdout = 1;
  
  // does chdir() call iput(p->cwd) in a transaction?
  void iputtest(void)
  {
      printf(stdout, "iput test\n");
  
      if (mkdir("iputdir") < 0)
      {
          printf(stdout, "mkdir failed\n");
          exit();
      }
      if (chdir("iputdir") < 0)
      {
          printf(stdout, "chdir iputdir failed\n");
          exit();
      }
      if (unlink("../iputdir") < 0)
      {
          printf(stdout, "unlink ../iputdir failed\n");
          exit();
      }
      if (chdir("/") < 0)
      {
          printf(stdout, "chdir / failed\n");
          exit();
      }
      printf(stdout, "iput test ok\n");
  }
  
  // does exit() call iput(p->cwd) in a transaction?
  void exitiputtest(void)
  {
      int pid;
  
      printf(stdout, "exitiput test\n");
  
      pid = fork();
      if (pid < 0)
      {
          printf(stdout, "fork failed\n");
          exit();
      }
      if (pid == 0)
      {
          if (mkdir("iputdir") < 0)
          {
              printf(stdout, "mkdir failed\n");
              exit();
          }
          if (chdir("iputdir") < 0)
          {
              printf(stdout, "child chdir failed\n");
              exit();
          }
          if (unlink("../iputdir") < 0)
          {
              printf(stdout, "unlink ../iputdir failed\n");
              exit();
          }
          exit();
      }
      wait();
      printf(stdout, "exitiput test ok\n");
  }
  
  // does the error path in open() for attempt to write a
  // directory call iput() in a transaction?
  // needs a hacked kernel that pauses just after the namei()
  // call in sys_open():
  //    if((ip = namei(path)) == 0)
  //      return -1;
  //    {
  //      int i;
  //      for(i = 0; i < 10000; i++)
  //        yield();
  //    }
  void openiputtest(void)
  {
      int pid;
  
      printf(stdout, "openiput test\n");
      if (mkdir("oidir") < 0)
      {
          printf(stdout, "mkdir oidir failed\n");
          exit();
      }
      pid = fork();
      if (pid < 0)
      {
          printf(stdout, "fork failed\n");
          exit();
      }
      if (pid == 0)
      {
          int fd = open("oidir", O_RDWR);
          if (fd >= 0)
          {
              printf(stdout, "open directory for write succeeded\n");
              exit();
          }
          exit();
      }
      sleep(1);
      if (unlink("oidir") != 0)
      {
          printf(stdout, "unlink failed\n");
          exit();
      }
      wait();
      printf(stdout, "openiput test ok\n");
  }
  
  // simple file system tests
  
  void opentest(void)
  {
      int fd;
  
      printf(stdout, "open test\n");
      fd = open("echo", 0);
      if (fd < 0)
      {
          printf(stdout, "open echo failed!\n");
          exit();
      }
      close(fd);
      fd = open("doesnotexist", 0);
      if (fd >= 0)
      {
          printf(stdout, "open doesnotexist succeeded!\n");
          exit();
      }
      printf(stdout, "open test ok\n");
  }
  
  void writetest(void)
  {
      int fd;
      int i;
  
      printf(stdout, "small file test\n");
      fd = open("small", O_CREATE | O_RDWR);
      if (fd >= 0)
      {
          printf(stdout, "creat small succeeded; ok\n");
      }
      else
      {
          printf(stdout, "error: creat small failed!\n");
          exit();
      }
      for (i = 0; i < 100; i++)
      {
          if (write(fd, "aaaaaaaaaa", 10) != 10)
          {
              printf(stdout, "error: write aa %d new file failed\n", i);
              exit();
          }
          if (write(fd, "bbbbbbbbbb", 10) != 10)
          {
              printf(stdout, "error: write bb %d new file failed\n", i);
              exit();
          }
      }
      printf(stdout, "writes ok\n");
      close(fd);
      fd = open("small", O_RDONLY);
      if (fd >= 0)
      {
          printf(stdout, "open small succeeded ok\n");
      }
      else
      {
          printf(stdout, "error: open small failed!\n");
          exit();
      }
      i = read(fd, buf, 2000);
      if (i == 2000)
      {
          printf(stdout, "read succeeded ok\n");
      }
      else
      {
          printf(stdout, "read failed\n");
          exit();
      }
      close(fd);
  
      if (unlink("small") < 0)
      {
          printf(stdout, "unlink small failed\n");
          exit();
      }
      printf(stdout, "small file test ok\n");
  }
  
  void writetest1(void)
  {
      int i, fd, n;
  
      printf(stdout, "big files test\n");
  
      fd = open("big", O_CREATE | O_RDWR);
      if (fd < 0)
      {
          printf(stdout, "error: creat big failed!\n");
          exit();
      }
  
      for (i = 0; i < MAXFILE; i++)
      {
          ((int *)buf)[0] = i;
          if (write(fd, buf, 512) != 512)
          {
              printf(stdout, "error: write big file failed\n", i);
              exit();
          }
      }
  
      close(fd);
  
      fd = open("big", O_RDONLY);
      if (fd < 0)
      {
          printf(stdout, "error: open big failed!\n");
          exit();
      }
  
      n = 0;
      for (;;)
      {
          i = read(fd, buf, 512);
          if (i == 0)
          {
              if (n == MAXFILE - 1)
              {
                  printf(stdout, "read only %d blocks from big", n);
                  exit();
              }
              break;
          }
          else if (i != 512)
          {
              printf(stdout, "read failed %d\n", i);
              exit();
          }
          if (((int *)buf)[0] != n)
          {
              printf(stdout, "read content of block %d is %d\n",
                     n, ((int *)buf)[0]);
              exit();
          }
          n++;
      }
      close(fd);
      if (unlink("big") < 0)
      {
          printf(stdout, "unlink big failed\n");
          exit();
      }
      printf(stdout, "big files ok\n");
  }
  
  void createtest(void)
  {
      int i, fd;
  
      printf(stdout, "many creates, followed by unlink test\n");
  
      name[0] = 'a';
      name[2] = '\0';
      for (i = 0; i < 52; i++)
      {
          name[1] = '0' + i;
          fd = open(name, O_CREATE | O_RDWR);
          close(fd);
      }
      name[0] = 'a';
      name[2] = '\0';
      for (i = 0; i < 52; i++)
      {
          name[1] = '0' + i;
          unlink(name);
      }
      printf(stdout, "many creates, followed by unlink; ok\n");
  }
  
  void dirtest(void)
  {
      printf(stdout, "mkdir test\n");
  
      if (mkdir("dir0") < 0)
      {
          printf(stdout, "mkdir failed\n");
          exit();
      }
  
      if (chdir("dir0") < 0)
      {
          printf(stdout, "chdir dir0 failed\n");
          exit();
      }
  
      if (chdir("..") < 0)
      {
          printf(stdout, "chdir .. failed\n");
          exit();
      }
  
      if (unlink("dir0") < 0)
      {
          printf(stdout, "unlink dir0 failed\n");
          exit();
      }
      printf(stdout, "mkdir test ok\n");
  }
  
  void exectest(void)
  {
      printf(stdout, "exec test\n");
      if (exec("echo", echoargv) < 0)
      {
          printf(stdout, "exec echo failed\n");
          exit();
      }
  }
  
  // simple fork and pipe read/write
  
  void pipe1(void)
  {
      int fds[2], pid;
      int seq, i, n, cc, total;
  
      if (pipe(fds) != 0)
      {
          printf(1, "pipe() failed\n");
          exit();
      }
      pid = fork();
      seq = 0;
      if (pid == 0)
      {
          close(fds[0]);
          for (n = 0; n < 5; n++)
          {
              for (i = 0; i < 1033; i++)
                  buf[i] = seq++;
              if (write(fds[1], buf, 1033) != 1033)
              {
                  printf(1, "pipe1 oops 1\n");
                  exit();
              }
          }
          exit();
      }
      else if (pid > 0)
      {
          close(fds[1]);
          total = 0;
          cc = 1;
          while ((n = read(fds[0], buf, cc)) > 0)
          {
              for (i = 0; i < n; i++)
              {
                  if ((buf[i] & 0xff) != (seq++ & 0xff))
                  {
                      printf(1, "pipe1 oops 2\n");
                      return;
                  }
              }
              total += n;
              cc = cc * 2;
              if (cc > sizeof(buf))
                  cc = sizeof(buf);
          }
          if (total != 5 * 1033)
          {
              printf(1, "pipe1 oops 3 total %d\n", total);
              exit();
          }
          close(fds[0]);
          wait();
      }
      else
      {
          printf(1, "fork() failed\n");
          exit();
      }
      printf(1, "pipe1 ok\n");
  }
  
  // meant to be run w/ at most two CPUs
  void preempt(void)
  {
      int pid1, pid2, pid3;
      int pfds[2];
  
      printf(1, "preempt: ");
      pid1 = fork();
      if (pid1 == 0)
          for (;;)
              ;
  
      pid2 = fork();
      if (pid2 == 0)
          for (;;)
              ;
  
      pipe(pfds);
      pid3 = fork();
      if (pid3 == 0)
      {
          close(pfds[0]);
          if (write(pfds[1], "x", 1) != 1)
              printf(1, "preempt write error");
          close(pfds[1]);
          for (;;)
              ;
      }
  
      close(pfds[1]);
      if (read(pfds[0], buf, sizeof(buf)) != 1)
      {
          printf(1, "preempt read error");
          return;
      }
      close(pfds[0]);
      printf(1, "kill... ");
      kill(pid1);
      kill(pid2);
      kill(pid3);
      printf(1, "wait... ");
      wait();
      wait();
      wait();
      printf(1, "preempt ok\n");
  }
  
  // try to find any races between exit and wait
  void exitwait(void)
  {
      int i, pid;
  
      for (i = 0; i < 100; i++)
      {
          pid = fork();
          if (pid < 0)
          {
              printf(1, "fork failed\n");
              return;
          }
          if (pid)
          {
              if (wait() != pid)
              {
                  printf(1, "wait wrong pid\n");
                  return;
              }
          }
          else
          {
              exit();
          }
      }
      printf(1, "exitwait ok\n");
  }
  
  void mem(void)
  {
      void *m1, *m2;
      int pid, ppid;
  
      printf(1, "mem test\n");
      ppid = getpid();
      if ((pid = fork()) == 0)
      {
          m1 = 0;
          while ((m2 = malloc(10001)) != 0)
          {
              *(char **)m2 = m1;
              m1 = m2;
          }
          while (m1)
          {
              m2 = *(char **)m1;
              free(m1);
              m1 = m2;
          }
          m1 = malloc(1024 * 20);
          if (m1 == 0)
          {
              printf(1, "couldn't allocate mem?!!\n");
              kill(ppid);
              exit();
          }
          free(m1);
          printf(1, "mem ok\n");
          exit();
      }
      else
      {
          wait();
      }
  }
  
  // More file system tests
  
  // two processes write to the same file descriptor
  // is the offset shared? does inode locking work?
  void sharedfd(void)
  {
      int fd, pid, i, n, nc, np;
      char buf[10];
  
      printf(1, "sharedfd test\n");
  
      unlink("sharedfd");
      fd = open("sharedfd", O_CREATE | O_RDWR);
      if (fd < 0)
      {
          printf(1, "fstests: cannot open sharedfd for writing");
          return;
      }
      pid = fork();
      memset(buf, pid == 0 ? 'c' : 'p', sizeof(buf));
      for (i = 0; i < 1000; i++)
      {
          if (write(fd, buf, sizeof(buf)) != sizeof(buf))
          {
              printf(1, "fstests: write sharedfd failed\n");
              break;
          }
      }
      if (pid == 0)
          exit();
      else
          wait();
      close(fd);
      fd = open("sharedfd", 0);
      if (fd < 0)
      {
          printf(1, "fstests: cannot open sharedfd for reading\n");
          return;
      }
      nc = np = 0;
      while ((n = read(fd, buf, sizeof(buf))) > 0)
      {
          for (i = 0; i < sizeof(buf); i++)
          {
              if (buf[i] == 'c')
                  nc++;
              if (buf[i] == 'p')
                  np++;
          }
      }
      close(fd);
      unlink("sharedfd");
      if (nc == 10000 && np == 10000)
      {
          printf(1, "sharedfd ok\n");
      }
      else
      {
          printf(1, "sharedfd oops %d %d\n", nc, np);
          exit();
      }
  }
  
  // four processes write different files at the same
  // time, to test block allocation.
  void fourfiles(void)
  {
      int fd, pid, i, j, n, total, pi;
      char *names[] = {"f0", "f1", "f2", "f3"};
      char *fname;
  
      printf(1, "fourfiles test\n");
  
      for (pi = 0; pi < 4; pi++)
      {
          fname = names[pi];
          unlink(fname);
  
          pid = fork();
          if (pid < 0)
          {
              printf(1, "fork failed\n");
              exit();
          }
  
          if (pid == 0)
          {
              fd = open(fname, O_CREATE | O_RDWR);
              if (fd < 0)
              {
                  printf(1, "create failed\n");
                  exit();
              }
  
              memset(buf, '0' + pi, 512);
              for (i = 0; i < 12; i++)
              {
                  if ((n = write(fd, buf, 500)) != 500)
                  {
                      printf(1, "write failed %d\n", n);
                      exit();
                  }
              }
              exit();
          }
      }
  
      for (pi = 0; pi < 4; pi++)
      {
          wait();
      }
  
      for (i = 0; i < 2; i++)
      {
          fname = names[i];
          fd = open(fname, 0);
          total = 0;
          while ((n = read(fd, buf, sizeof(buf))) > 0)
          {
              for (j = 0; j < n; j++)
              {
                  if (buf[j] != '0' + i)
                  {
                      printf(1, "wrong char\n");
                      exit();
                  }
              }
              total += n;
          }
          close(fd);
          if (total != 12 * 500)
          {
              printf(1, "wrong length %d\n", total);
              exit();
          }
          unlink(fname);
      }
  
      printf(1, "fourfiles ok\n");
  }
  
  // four processes create and delete different files in same directory
  void createdelete(void)
  {
      enum
      {
          N = 20
      };
      int pid, i, fd, pi;
      char name[32];
  
      printf(1, "createdelete test\n");
  
      for (pi = 0; pi < 4; pi++)
      {
          pid = fork();
          if (pid < 0)
          {
              printf(1, "fork failed\n");
              exit();
          }
  
          if (pid == 0)
          {
              name[0] = 'p' + pi;
              name[2] = '\0';
              for (i = 0; i < N; i++)
              {
                  name[1] = '0' + i;
                  fd = open(name, O_CREATE | O_RDWR);
                  if (fd < 0)
                  {
                      printf(1, "create failed\n");
                      exit();
                  }
                  close(fd);
                  if (i > 0 && (i % 2) == 0)
                  {
                      name[1] = '0' + (i / 2);
                      if (unlink(name) < 0)
                      {
                          printf(1, "unlink failed\n");
                          exit();
                      }
                  }
              }
              exit();
          }
      }
  
      for (pi = 0; pi < 4; pi++)
      {
          wait();
      }
  
      name[0] = name[1] = name[2] = 0;
      for (i = 0; i < N; i++)
      {
          for (pi = 0; pi < 4; pi++)
          {
              name[0] = 'p' + pi;
              name[1] = '0' + i;
              fd = open(name, 0);
              if ((i == 0 || i >= N / 2) && fd < 0)
              {
                  printf(1, "oops createdelete %s didn't exist\n", name);
                  exit();
              }
              else if ((i >= 1 && i < N / 2) && fd >= 0)
              {
                  printf(1, "oops createdelete %s did exist\n", name);
                  exit();
              }
              if (fd >= 0)
                  close(fd);
          }
      }
  
      for (i = 0; i < N; i++)
      {
          for (pi = 0; pi < 4; pi++)
          {
              name[0] = 'p' + i;
              name[1] = '0' + i;
              unlink(name);
          }
      }
  
      printf(1, "createdelete ok\n");
  }
  
  // can I unlink a file and still read it?
  void unlinkread(void)
  {
      int fd, fd1;
  
      printf(1, "unlinkread test\n");
      fd = open("unlinkread", O_CREATE | O_RDWR);
      if (fd < 0)
      {
          printf(1, "create unlinkread failed\n");
          exit();
      }
      write(fd, "hello", 5);
      close(fd);
  
      fd = open("unlinkread", O_RDWR);
      if (fd < 0)
      {
          printf(1, "open unlinkread failed\n");
          exit();
      }
      if (unlink("unlinkread") != 0)
      {
          printf(1, "unlink unlinkread failed\n");
          exit();
      }
  
      fd1 = open("unlinkread", O_CREATE | O_RDWR);
      write(fd1, "yyy", 3);
      close(fd1);
  
      if (read(fd, buf, sizeof(buf)) != 5)
      {
          printf(1, "unlinkread read failed");
          exit();
      }
      if (buf[0] != 'h')
      {
          printf(1, "unlinkread wrong data\n");
          exit();
      }
      if (write(fd, buf, 10) != 10)
      {
          printf(1, "unlinkread write failed\n");
          exit();
      }
      close(fd);
      unlink("unlinkread");
      printf(1, "unlinkread ok\n");
  }
  
  void linktest(void)
  {
      int fd;
  
      printf(1, "linktest\n");
  
      unlink("lf1");
      unlink("lf2");
  
      fd = open("lf1", O_CREATE | O_RDWR);
      if (fd < 0)
      {
          printf(1, "create lf1 failed\n");
          exit();
      }
      if (write(fd, "hello", 5) != 5)
      {
          printf(1, "write lf1 failed\n");
          exit();
      }
      close(fd);
  
      if (link("lf1", "lf2") < 0)
      {
          printf(1, "link lf1 lf2 failed\n");
          exit();
      }
      unlink("lf1");
  
      if (open("lf1", 0) >= 0)
      {
          printf(1, "unlinked lf1 but it is still there!\n");
          exit();
      }
  
      fd = open("lf2", 0);
      if (fd < 0)
      {
          printf(1, "open lf2 failed\n");
          exit();
      }
      if (read(fd, buf, sizeof(buf)) != 5)
      {
          printf(1, "read lf2 failed\n");
          exit();
      }
      close(fd);
  
      if (link("lf2", "lf2") >= 0)
      {
          printf(1, "link lf2 lf2 succeeded! oops\n");
          exit();
      }
  
      unlink("lf2");
      if (link("lf2", "lf1") >= 0)
      {
          printf(1, "link non-existant succeeded! oops\n");
          exit();
      }
  
      if (link(".", "lf1") >= 0)
      {
          printf(1, "link . lf1 succeeded! oops\n");
          exit();
      }
  
      printf(1, "linktest ok\n");
  }
  
  // test concurrent create/link/unlink of the same file
  void concreate(void)
  {
      char file[3];
      int i, pid, n, fd;
      char fa[40];
      struct
      {
          ushort inum;
          char name[14];
      } de;
  
      printf(1, "concreate test\n");
      file[0] = 'C';
      file[2] = '\0';
      for (i = 0; i < 40; i++)
      {
          file[1] = '0' + i;
          unlink(file);
          pid = fork();
          if (pid && (i % 3) == 1)
          {
              link("C0", file);
          }
          else if (pid == 0 && (i % 5) == 1)
          {
              link("C0", file);
          }
          else
          {
              fd = open(file, O_CREATE | O_RDWR);
              if (fd < 0)
              {
                  printf(1, "concreate create %s failed\n", file);
                  exit();
              }
              close(fd);
          }
          if (pid == 0)
              exit();
          else
              wait();
      }
  
      memset(fa, 0, sizeof(fa));
      fd = open(".", 0);
      n = 0;
      while (read(fd, &de, sizeof(de)) > 0)
      {
          if (de.inum == 0)
              continue;
          if (de.name[0] == 'C' && de.name[2] == '\0')
          {
              i = de.name[1] - '0';
              if (i < 0 || i >= sizeof(fa))
              {
                  printf(1, "concreate weird file %s\n", de.name);
                  exit();
              }
              if (fa[i])
              {
                  printf(1, "concreate duplicate file %s\n", de.name);
                  exit();
              }
              fa[i] = 1;
              n++;
          }
      }
      close(fd);
  
      if (n != 40)
      {
          printf(1, "concreate not enough files in directory listing\n");
          exit();
      }
  
      for (i = 0; i < 40; i++)
      {
          file[1] = '0' + i;
          pid = fork();
          if (pid < 0)
          {
              printf(1, "fork failed\n");
              exit();
          }
          if (((i % 3) == 0 && pid == 0) ||
              ((i % 3) == 1 && pid != 0))
          {
              close(open(file, 0));
              close(open(file, 0));
              close(open(file, 0));
              close(open(file, 0));
          }
          else
          {
              unlink(file);
              unlink(file);
              unlink(file);
              unlink(file);
          }
          if (pid == 0)
              exit();
          else
              wait();
      }
  
      printf(1, "concreate ok\n");
  }
  
  // another concurrent link/unlink/create test,
  // to look for deadlocks.
  void linkunlink()
  {
      int pid, i;
  
      printf(1, "linkunlink test\n");
  
      unlink("x");
      pid = fork();
      if (pid < 0)
      {
          printf(1, "fork failed\n");
          exit();
      }
  
      unsigned int x = (pid ? 1 : 97);
      for (i = 0; i < 100; i++)
      {
          x = x * 1103515245 + 12345;
          if ((x % 3) == 0)
          {
              close(open("x", O_RDWR | O_CREATE));
          }
          else if ((x % 3) == 1)
          {
              link("cat", "x");
          }
          else
          {
              unlink("x");
          }
      }
  
      if (pid)
          wait();
      else
          exit();
  
      printf(1, "linkunlink ok\n");
  }
  
  // directory that uses indirect blocks
  void bigdir(void)
  {
      int i, fd;
      char name[10];
  
      printf(1, "bigdir test\n");
      unlink("bd");
  
      fd = open("bd", O_CREATE);
      if (fd < 0)
      {
          printf(1, "bigdir create failed\n");
          exit();
      }
      close(fd);
  
      for (i = 0; i < 500; i++)
      {
          name[0] = 'x';
          name[1] = '0' + (i / 64);
          name[2] = '0' + (i % 64);
          name[3] = '\0';
          if (link("bd", name) != 0)
          {
              printf(1, "bigdir link failed\n");
              exit();
          }
      }
  
      unlink("bd");
      for (i = 0; i < 500; i++)
      {
          name[0] = 'x';
          name[1] = '0' + (i / 64);
          name[2] = '0' + (i % 64);
          name[3] = '\0';
          if (unlink(name) != 0)
          {
              printf(1, "bigdir unlink failed");
              exit();
          }
      }
  
      printf(1, "bigdir ok\n");
  }
  
  void subdir(void)
  {
      int fd, cc;
  
      printf(1, "subdir test\n");
  
      unlink("ff");
      if (mkdir("dd") != 0)
      {
          printf(1, "subdir mkdir dd failed\n");
          exit();
      }
  
      fd = open("dd/ff", O_CREATE | O_RDWR);
      if (fd < 0)
      {
          printf(1, "create dd/ff failed\n");
          exit();
      }
      write(fd, "ff", 2);
      close(fd);
  
      if (unlink("dd") >= 0)
      {
          printf(1, "unlink dd (non-empty dir) succeeded!\n");
          exit();
      }
  
      if (mkdir("/dd/dd") != 0)
      {
          printf(1, "subdir mkdir dd/dd failed\n");
          exit();
      }
  
      fd = open("dd/dd/ff", O_CREATE | O_RDWR);
      if (fd < 0)
      {
          printf(1, "create dd/dd/ff failed\n");
          exit();
      }
      write(fd, "FF", 2);
      close(fd);
  
      fd = open("dd/dd/../ff", 0);
      if (fd < 0)
      {
          printf(1, "open dd/dd/../ff failed\n");
          exit();
      }
      cc = read(fd, buf, sizeof(buf));
      if (cc != 2 || buf[0] != 'f')
      {
          printf(1, "dd/dd/../ff wrong content\n");
          exit();
      }
      close(fd);
  
      if (link("dd/dd/ff", "dd/dd/ffff") != 0)
      {
          printf(1, "link dd/dd/ff dd/dd/ffff failed\n");
          exit();
      }
  
      if (unlink("dd/dd/ff") != 0)
      {
          printf(1, "unlink dd/dd/ff failed\n");
          exit();
      }
      if (open("dd/dd/ff", O_RDONLY) >= 0)
      {
          printf(1, "open (unlinked) dd/dd/ff succeeded\n");
          exit();
      }
  
      if (chdir("dd") != 0)
      {
          printf(1, "chdir dd failed\n");
          exit();
      }
      if (chdir("dd/../../dd") != 0)
      {
          printf(1, "chdir dd/../../dd failed\n");
          exit();
      }
      if (chdir("dd/../../../dd") != 0)
      {
          printf(1, "chdir dd/../../dd failed\n");
          exit();
      }
      if (chdir("./..") != 0)
      {
          printf(1, "chdir ./.. failed\n");
          exit();
      }
  
      fd = open("dd/dd/ffff", 0);
      if (fd < 0)
      {
          printf(1, "open dd/dd/ffff failed\n");
          exit();
      }
      if (read(fd, buf, sizeof(buf)) != 2)
      {
          printf(1, "read dd/dd/ffff wrong len\n");
          exit();
      }
      close(fd);
  
      if (open("dd/dd/ff", O_RDONLY) >= 0)
      {
          printf(1, "open (unlinked) dd/dd/ff succeeded!\n");
          exit();
      }
  
      if (open("dd/ff/ff", O_CREATE | O_RDWR) >= 0)
      {
          printf(1, "create dd/ff/ff succeeded!\n");
          exit();
      }
      if (open("dd/xx/ff", O_CREATE | O_RDWR) >= 0)
      {
          printf(1, "create dd/xx/ff succeeded!\n");
          exit();
      }
      if (open("dd", O_CREATE) >= 0)
      {
          printf(1, "create dd succeeded!\n");
          exit();
      }
      if (open("dd", O_RDWR) >= 0)
      {
          printf(1, "open dd rdwr succeeded!\n");
          exit();
      }
      if (open("dd", O_WRONLY) >= 0)
      {
          printf(1, "open dd wronly succeeded!\n");
          exit();
      }
      if (link("dd/ff/ff", "dd/dd/xx") == 0)
      {
          printf(1, "link dd/ff/ff dd/dd/xx succeeded!\n");
          exit();
      }
      if (link("dd/xx/ff", "dd/dd/xx") == 0)
      {
          printf(1, "link dd/xx/ff dd/dd/xx succeeded!\n");
          exit();
      }
      if (link("dd/ff", "dd/dd/ffff") == 0)
      {
          printf(1, "link dd/ff dd/dd/ffff succeeded!\n");
          exit();
      }
      if (mkdir("dd/ff/ff") == 0)
      {
          printf(1, "mkdir dd/ff/ff succeeded!\n");
          exit();
      }
      if (mkdir("dd/xx/ff") == 0)
      {
          printf(1, "mkdir dd/xx/ff succeeded!\n");
          exit();
      }
      if (mkdir("dd/dd/ffff") == 0)
      {
          printf(1, "mkdir dd/dd/ffff succeeded!\n");
          exit();
      }
      if (unlink("dd/xx/ff") == 0)
      {
          printf(1, "unlink dd/xx/ff succeeded!\n");
          exit();
      }
      if (unlink("dd/ff/ff") == 0)
      {
          printf(1, "unlink dd/ff/ff succeeded!\n");
          exit();
      }
      if (chdir("dd/ff") == 0)
      {
          printf(1, "chdir dd/ff succeeded!\n");
          exit();
      }
      if (chdir("dd/xx") == 0)
      {
          printf(1, "chdir dd/xx succeeded!\n");
          exit();
      }
  
      if (unlink("dd/dd/ffff") != 0)
      {
          printf(1, "unlink dd/dd/ff failed\n");
          exit();
      }
      if (unlink("dd/ff") != 0)
      {
          printf(1, "unlink dd/ff failed\n");
          exit();
      }
      if (unlink("dd") == 0)
      {
          printf(1, "unlink non-empty dd succeeded!\n");
          exit();
      }
      if (unlink("dd/dd") < 0)
      {
          printf(1, "unlink dd/dd failed\n");
          exit();
      }
      if (unlink("dd") < 0)
      {
          printf(1, "unlink dd failed\n");
          exit();
      }
  
      printf(1, "subdir ok\n");
  }
  
  // test writes that are larger than the log.
  void bigwrite(void)
  {
      int fd, sz;
  
      printf(1, "bigwrite test\n");
  
      unlink("bigwrite");
      for (sz = 499; sz < 12 * 512; sz += 471)
      {
          fd = open("bigwrite", O_CREATE | O_RDWR);
          if (fd < 0)
          {
              printf(1, "cannot create bigwrite\n");
              exit();
          }
          int i;
          for (i = 0; i < 2; i++)
          {
              int cc = write(fd, buf, sz);
              if (cc != sz)
              {
                  printf(1, "write(%d) ret %d\n", sz, cc);
                  exit();
              }
          }
          close(fd);
          unlink("bigwrite");
      }
  
      printf(1, "bigwrite ok\n");
  }
  
  void bigfile(void)
  {
      int fd, i, total, cc;
  
      printf(1, "bigfile test\n");
  
      unlink("bigfile");
      fd = open("bigfile", O_CREATE | O_RDWR);
      if (fd < 0)
      {
          printf(1, "cannot create bigfile");
          exit();
      }
      for (i = 0; i < 20; i++)
      {
          memset(buf, i, 600);
          if (write(fd, buf, 600) != 600)
          {
              printf(1, "write bigfile failed\n");
              exit();
          }
      }
      close(fd);
  
      fd = open("bigfile", 0);
      if (fd < 0)
      {
          printf(1, "cannot open bigfile\n");
          exit();
      }
      total = 0;
      for (i = 0;; i++)
      {
          cc = read(fd, buf, 300);
          if (cc < 0)
          {
              printf(1, "read bigfile failed\n");
              exit();
          }
          if (cc == 0)
              break;
          if (cc != 300)
          {
              printf(1, "short read bigfile\n");
              exit();
          }
          if (buf[0] != i / 2 || buf[299] != i / 2)
          {
              printf(1, "read bigfile wrong data\n");
              exit();
          }
          total += cc;
      }
      close(fd);
      if (total != 20 * 600)
      {
          printf(1, "read bigfile wrong total\n");
          exit();
      }
      unlink("bigfile");
  
      printf(1, "bigfile test ok\n");
  }
  
  void fourteen(void)
  {
      int fd;
  
      // DIRSIZ is 14.
      printf(1, "fourteen test\n");
  
      if (mkdir("12345678901234") != 0)
      {
          printf(1, "mkdir 12345678901234 failed\n");
          exit();
      }
      if (mkdir("12345678901234/123456789012345") != 0)
      {
          printf(1, "mkdir 12345678901234/123456789012345 failed\n");
          exit();
      }
      fd = open("123456789012345/123456789012345/123456789012345", O_CREATE);
      if (fd < 0)
      {
          printf(1, "create 123456789012345/123456789012345/123456789012345 failed\n");
          exit();
      }
      close(fd);
      fd = open("12345678901234/12345678901234/12345678901234", 0);
      if (fd < 0)
      {
          printf(1, "open 12345678901234/12345678901234/12345678901234 failed\n");
          exit();
      }
      close(fd);
  
      if (mkdir("12345678901234/12345678901234") == 0)
      {
          printf(1, "mkdir 12345678901234/12345678901234 succeeded!\n");
          exit();
      }
      if (mkdir("123456789012345/12345678901234") == 0)
      {
          printf(1, "mkdir 12345678901234/123456789012345 succeeded!\n");
          exit();
      }
  
      printf(1, "fourteen ok\n");
  }
  
  void rmdot(void)
  {
      printf(1, "rmdot test\n");
      if (mkdir("dots") != 0)
      {
          printf(1, "mkdir dots failed\n");
          exit();
      }
      if (chdir("dots") != 0)
      {
          printf(1, "chdir dots failed\n");
          exit();
      }
      if (unlink(".") == 0)
      {
          printf(1, "rm . worked!\n");
          exit();
      }
      if (unlink("..") == 0)
      {
          printf(1, "rm .. worked!\n");
          exit();
      }
      if (chdir("/") != 0)
      {
          printf(1, "chdir / failed\n");
          exit();
      }
      if (unlink("dots/.") == 0)
      {
          printf(1, "unlink dots/. worked!\n");
          exit();
      }
      if (unlink("dots/..") == 0)
      {
          printf(1, "unlink dots/.. worked!\n");
          exit();
      }
      if (unlink("dots") != 0)
      {
          printf(1, "unlink dots failed!\n");
          exit();
      }
      printf(1, "rmdot ok\n");
  }
  
  void dirfile(void)
  {
      int fd;
  
      printf(1, "dir vs file\n");
  
      fd = open("dirfile", O_CREATE);
      if (fd < 0)
      {
          printf(1, "create dirfile failed\n");
          exit();
      }
      close(fd);
      if (chdir("dirfile") == 0)
      {
          printf(1, "chdir dirfile succeeded!\n");
          exit();
      }
      fd = open("dirfile/xx", 0);
      if (fd >= 0)
      {
          printf(1, "create dirfile/xx succeeded!\n");
          exit();
      }
      fd = open("dirfile/xx", O_CREATE);
      if (fd >= 0)
      {
          printf(1, "create dirfile/xx succeeded!\n");
          exit();
      }
      if (mkdir("dirfile/xx") == 0)
      {
          printf(1, "mkdir dirfile/xx succeeded!\n");
          exit();
      }
      if (unlink("dirfile/xx") == 0)
      {
          printf(1, "unlink dirfile/xx succeeded!\n");
          exit();
      }
      if (link("README", "dirfile/xx") == 0)
      {
          printf(1, "link to dirfile/xx succeeded!\n");
          exit();
      }
      if (unlink("dirfile") != 0)
      {
          printf(1, "unlink dirfile failed!\n");
          exit();
      }
  
      fd = open(".", O_RDWR);
      if (fd >= 0)
      {
          printf(1, "open . for writing succeeded!\n");
          exit();
      }
      fd = open(".", 0);
      if (write(fd, "x", 1) > 0)
      {
          printf(1, "write . succeeded!\n");
          exit();
      }
      close(fd);
  
      printf(1, "dir vs file OK\n");
  }
  
  // test that iput() is called at the end of _namei()
  void iref(void)
  {
      int i, fd;
  
      printf(1, "empty file name\n");
  
      // the 50 is NINODE
      for (i = 0; i < 50 + 1; i++)
      {
          if (mkdir("irefd") != 0)
          {
              printf(1, "mkdir irefd failed\n");
              exit();
          }
          if (chdir("irefd") != 0)
          {
              printf(1, "chdir irefd failed\n");
              exit();
          }
  
          mkdir("");
          link("README", "");
          fd = open("", O_CREATE);
          if (fd >= 0)
              close(fd);
          fd = open("xx", O_CREATE);
          if (fd >= 0)
              close(fd);
          unlink("xx");
      }
  
      chdir("/");
      printf(1, "empty file name OK\n");
  }
  
  // test that fork fails gracefully
  // the forktest binary also does this, but it runs out of proc entries first.
  // inside the bigger usertests binary, we run out of memory first.
  void forktest(void)
  {
      int n, pid;
  
      printf(1, "fork test\n");
  
      for (n = 0; n < 1000; n++)
      {
          pid = fork();
          if (pid < 0)
              break;
          if (pid == 0)
              exit();
      }
  
      if (n == 1000)
      {
          printf(1, "fork claimed to work 1000 times!\n");
          exit();
      }
  
      for (; n > 0; n--)
      {
          if (wait() < 0)
          {
              printf(1, "wait stopped early\n");
              exit();
          }
      }
  
      if (wait() != -1)
      {
          printf(1, "wait got too many\n");
          exit();
      }
  
      printf(1, "fork test OK\n");
  }
  
  void sbrktest(void)
  {
      int fds[2], pid, pids[10], ppid;
      char *a, *b, *c, *lastaddr, *oldbrk, *p, scratch;
      uint amt;
  
      printf(stdout, "sbrk test\n");
      oldbrk = sbrk(0);
  
      // can one sbrk() less than a page?
      a = sbrk(0);
      int i;
      for (i = 0; i < 5000; i++)
      {
          b = sbrk(1);
          if (b != a)
          {
              printf(stdout, "sbrk test failed %d %x %x\n", i, a, b);
              exit();
          }
          *b = 1;
          a = b + 1;
      }
      pid = fork();
      if (pid < 0)
      {
          printf(stdout, "sbrk test fork failed\n");
          exit();
      }
      c = sbrk(1);
      c = sbrk(1);
      if (c != a + 1)
      {
          printf(stdout, "sbrk test failed post-fork\n");
          exit();
      }
      if (pid == 0)
          exit();
      wait();
  
      // can one grow address space to something big?
  #define BIG (100 * 1024 * 1024)
      a = sbrk(0);
      amt = (BIG) - (uint)a;
      p = sbrk(amt);
      if (p != a)
      {
          printf(stdout, "sbrk test failed to grow big address space; enough phys mem?\n");
          exit();
      }
      lastaddr = (char *)(BIG - 1);
      *lastaddr = 99;
  
      // can one de-allocate?
      a = sbrk(0);
      c = sbrk(-4096);
      if (c == (char *)0xffffffff)
      {
          printf(stdout, "sbrk could not deallocate\n");
          exit();
      }
      c = sbrk(0);
      if (c != a - 4096)
      {
          printf(stdout, "sbrk deallocation produced wrong address, a %x c %x\n", a, c);
          exit();
      }
  
      // can one re-allocate that page?
      a = sbrk(0);
      c = sbrk(4096);
      if (c != a || sbrk(0) != a + 4096)
      {
          printf(stdout, "sbrk re-allocation failed, a %x c %x\n", a, c);
          exit();
      }
      if (*lastaddr == 99)
      {
          // should be zero
          printf(stdout, "sbrk de-allocation didn't really deallocate\n");
          exit();
      }
  
      a = sbrk(0);
      c = sbrk(-(sbrk(0) - oldbrk));
      if (c != a)
      {
          printf(stdout, "sbrk downsize failed, a %x c %x\n", a, c);
          exit();
      }
  
      // can we read the kernel's memory?
      for (a = (char *)(KERNBASE); a < (char *)(KERNBASE + 2000000); a += 50000)
      {
          ppid = getpid();
          pid = fork();
          if (pid < 0)
          {
              printf(stdout, "fork failed\n");
              exit();
          }
          if (pid == 0)
          {
              printf(stdout, "oops could read %x = %x\n", a, *a);
              kill(ppid);
              exit();
          }
          wait();
      }
  
      // if we run the system out of memory, does it clean up the last
      // failed allocation?
      if (pipe(fds) != 0)
      {
          printf(1, "pipe() failed\n");
          exit();
      }
      for (i = 0; i < sizeof(pids) / sizeof(pids[0]); i++)
      {
          if ((pids[i] = fork()) == 0)
          {
              // allocate a lot of memory
              sbrk(BIG - (uint)sbrk(0));
              write(fds[1], "x", 1);
              // sit around until killed
              for (;;)
                  sleep(1000);
          }
          if (pids[i] != -1)
              read(fds[0], &scratch, 1);
      }
      // if those failed allocations freed up the pages they did allocate,
      // we'll be able to allocate here
      c = sbrk(4096);
      for (i = 0; i < sizeof(pids) / sizeof(pids[0]); i++)
      {
          if (pids[i] == -1)
              continue;
          kill(pids[i]);
          wait();
      }
      if (c == (char *)0xffffffff)
      {
          printf(stdout, "failed sbrk leaked memory\n");
          exit();
      }
  
      if (sbrk(0) > oldbrk)
          sbrk(-(sbrk(0) - oldbrk));
  
      printf(stdout, "sbrk test OK\n");
  }
  
  void validateint(int *p)
  {
      int res;
      asm("mov %%esp, %%ebx\n\t"
          "mov %3, %%esp\n\t"
          "int %2\n\t"
          "mov %%ebx, %%esp"
          : "=a"(res)
          : "a"(SYS_sleep), "n"(T_SYSCALL), "c"(p)
          : "ebx");
  }
  
  void validatetest(void)
  {
      int hi, pid;
      uint p;
  
      printf(stdout, "validate test\n");
      hi = 1100 * 1024;
  
      for (p = 0; p <= (uint)hi; p += 4096)
      {
          if ((pid = fork()) == 0)
          {
              // try to crash the kernel by passing in a badly placed integer
              validateint((int *)p);
              exit();
          }
          sleep(0);
          sleep(0);
          kill(pid);
          wait();
  
          // try to crash the kernel by passing in a bad string pointer
          if (link("nosuchfile", (char *)p) != -1)
          {
              printf(stdout, "link should not succeed\n");
              exit();
          }
      }
  
      printf(stdout, "validate ok\n");
  }
  
  // does unintialized data start out zero?
  char uninit[10000];
  void bsstest(void)
  {
      int i;
  
      printf(stdout, "bss test\n");
      for (i = 0; i < sizeof(uninit); i++)
      {
          if (uninit[i] != '\0')
          {
              printf(stdout, "bss test failed\n");
              exit();
          }
      }
      printf(stdout, "bss test ok\n");
  }
  
  // does exec return an error if the arguments
  // are larger than a page? or does it write
  // below the stack and wreck the instructions/data?
  void bigargtest(void)
  {
      int pid, fd;
  
      unlink("bigarg-ok");
      pid = fork();
      if (pid == 0)
      {
          static char *args[MAXARG];
          int i;
          for (i = 0; i < MAXARG - 1; i++)
              args[i] = "bigargs test: failed\n                                                                                                                                                                                                       ";
          args[MAXARG - 1] = 0;
          printf(stdout, "bigarg test\n");
          exec("echo", args);
          printf(stdout, "bigarg test ok\n");
          fd = open("bigarg-ok", O_CREATE);
          close(fd);
          exit();
      }
      else if (pid < 0)
      {
          printf(stdout, "bigargtest: fork failed\n");
          exit();
      }
      wait();
      fd = open("bigarg-ok", 0);
      if (fd < 0)
      {
          printf(stdout, "bigarg test failed!\n");
          exit();
      }
      close(fd);
      unlink("bigarg-ok");
  }
  
  // what happens when the file system runs out of blocks?
  // answer: balloc panics, so this test is not useful.
  void fsfull()
  {
      int nfiles;
      int fsblocks = 0;
  
      printf(1, "fsfull test\n");
  
      for (nfiles = 0;; nfiles++)
      {
          char name[64];
          name[0] = 'f';
          name[1] = '0' + nfiles / 1000;
          name[2] = '0' + (nfiles % 1000) / 100;
          name[3] = '0' + (nfiles % 100) / 10;
          name[4] = '0' + (nfiles % 10);
          name[5] = '\0';
          printf(1, "writing %s\n", name);
          int fd = open(name, O_CREATE | O_RDWR);
          if (fd < 0)
          {
              printf(1, "open %s failed\n", name);
              break;
          }
          int total = 0;
          while (1)
          {
              int cc = write(fd, buf, 512);
              if (cc < 512)
                  break;
              total += cc;
              fsblocks++;
          }
          printf(1, "wrote %d bytes\n", total);
          close(fd);
          if (total == 0)
              break;
      }
  
      while (nfiles >= 0)
      {
          char name[64];
          name[0] = 'f';
          name[1] = '0' + nfiles / 1000;
          name[2] = '0' + (nfiles % 1000) / 100;
          name[3] = '0' + (nfiles % 100) / 10;
          name[4] = '0' + (nfiles % 10);
          name[5] = '\0';
          unlink(name);
          nfiles--;
      }
  
      printf(1, "fsfull test finished\n");
  }
  
  void uio()
  {
  #define RTC_ADDR 0x70
  #define RTC_DATA 0x71
  
      ushort port = 0;
      uchar val = 0;
      int pid;
  
      printf(1, "uio test\n");
      pid = fork();
      if (pid == 0)
      {
          port = RTC_ADDR;
          val = 0x09; /* year */
          /* http://wiki.osdev.org/Inline_Assembly/Examples */
          asm volatile("outb %0,%1" ::"a"(val), "d"(port));
          port = RTC_DATA;
          asm volatile("inb %1,%0"
                       : "=a"(val)
                       : "d"(port));
          printf(1, "uio: uio succeeded; test FAILED\n");
          exit();
      }
      else if (pid < 0)
      {
          printf(1, "fork failed\n");
          exit();
      }
      wait();
      printf(1, "uio test done\n");
  }
  
  void argptest()
  {
      int fd;
      fd = open("init", O_RDONLY);
      if (fd < 0)
      {
          printf(2, "open failed\n");
          exit();
      }
      read(fd, sbrk(0) - 1, -1);
      close(fd);
      printf(1, "arg test passed\n");
  }
  
  unsigned long randstate = 1;
  unsigned int
  rand()
  {
      randstate = randstate * 1664525 + 1013904223;
      return randstate;
  }
  
  int main(int argc, char *argv[])
  {
      printf(1, "usertests starting\n");
  
      if (open("usertests.ran", 0) >= 0)
      {
          printf(1, "already ran user tests -- rebuild fs.img\n");
          exit();
      }
      close(open("usertests.ran", O_CREATE));
  
      argptest();
      createdelete();
      linkunlink();
      concreate();
      fourfiles();
      sharedfd();
  
      bigargtest();
      bigwrite();
      bigargtest();
      bsstest();
      sbrktest();
      validatetest();
  
      opentest();
      writetest();
      writetest1();
      createtest();
  
      openiputtest();
      exitiputtest();
      iputtest();
  
      mem();
      pipe1();
      preempt();
      exitwait();
  
      rmdot();
      fourteen();
      bigfile();
      subdir();
      linktest();
      unlinkread();
      dirfile();
      iref();
      forktest();
      bigdir(); // slow
  
      uio();
  
      exectest();
  
      exit();
  }
  