grind: run parallel system calls forever

1 files changed, 160 insertions, 0 deletions

diff --git a/user/grind.c b/user/grind.c
new file mode 100644
index 0000000..97a8a93
--- /dev/null
+++ b/user/grind.c
@@ -0,0 +1,160 @@
+//
+// run random system calls in parallel forever.
+//
+
+#include "kernel/param.h"
+#include "kernel/types.h"
+#include "kernel/stat.h"
+#include "user/user.h"
+#include "kernel/fs.h"
+#include "kernel/fcntl.h"
+#include "kernel/syscall.h"
+#include "kernel/memlayout.h"
+#include "kernel/riscv.h"
+
+// from FreeBSD.
+int
+do_rand(unsigned long *ctx)
+{
+/*
+ * Compute x = (7^5 * x) mod (2^31 - 1)
+ * without overflowing 31 bits:
+ *      (2^31 - 1) = 127773 * (7^5) + 2836
+ * From "Random number generators: good ones are hard to find",
+ * Park and Miller, Communications of the ACM, vol. 31, no. 10,
+ * October 1988, p. 1195.
+ */
+    long hi, lo, x;
+
+    /* Transform to [1, 0x7ffffffe] range. */
+    x = (*ctx % 0x7ffffffe) + 1;
+    hi = x / 127773;
+    lo = x % 127773;
+    x = 16807 * lo - 2836 * hi;
+    if (x < 0)
+        x += 0x7fffffff;
+    /* Transform to [0, 0x7ffffffd] range. */
+    x--;
+    *ctx = x;
+    return (x);
+}
+
+unsigned long rand_next = 1;
+
+int
+rand(void)
+{
+    return (do_rand(&rand_next));
+}
+
+void
+go()
+{
+  int fd = -1;
+  static char buf[999];
+  char *break0 = sbrk(0);
+  
+  while(1){
+    int what = rand() % 20;
+    if(what == 1){
+      close(open("a", O_CREATE|O_RDWR));
+    } else if(what == 2){
+      close(open("b", O_CREATE|O_RDWR));
+    } else if(what == 3){
+      unlink("a");
+    } else if(what == 4){
+      unlink("b");
+    } else if(what == 5){
+      close(fd);
+      fd = open("a", O_CREATE|O_RDWR);
+    } else if(what == 6){
+      close(fd);
+      fd = open("b", O_CREATE|O_RDWR);
+    } else if(what == 7){
+      write(fd, buf, sizeof(buf));
+    } else if(what == 8){
+      read(fd, buf, sizeof(buf));
+    } else if(what == 9){
+      mkdir("a");
+    } else if(what == 10){
+      mkdir("b");
+    } else if(what == 11){
+      unlink("b");
+      link("a", "b");
+    } else if(what == 12){
+      unlink("a");
+      link("b", "a");
+    } else if(what == 13){
+      int pid = fork();
+      if(pid == 0){
+        exit(0);
+      }
+      wait(0);
+    } else if(what == 14){
+      int pid = fork();
+      if(pid == 0){
+        fork();
+        fork();
+        exit(0);
+      }
+      wait(0);
+    } else if(what == 15){
+      sbrk(6011);
+    } else if(what == 16){
+      if(sbrk(0) > break0)
+        sbrk(-(sbrk(0) - break0));
+    } else if(what == 17){
+      int pid = fork();
+      if(pid == 0){
+        close(open("a", O_CREATE|O_RDWR));
+        exit(0);
+      }
+      kill(pid);
+      wait(0);
+    } else if(what == 18){
+      int pid = fork();
+      if(pid == 0){
+        kill(getpid());
+        exit(0);
+      }
+      wait(0);
+    }
+  }
+}
+
+int
+main()
+{
+  int pid1 = fork();
+  if(pid1 < 0){
+    printf("grind: fork failed\n");
+    exit(1);
+  }
+  if(pid1 == 0){
+    rand_next = 31;
+    go();
+    exit(0);
+  }
+
+  int pid2 = fork();
+  if(pid2 < 0){
+    printf("grind: fork failed\n");
+    exit(1);
+  }
+  if(pid2 == 0){
+    rand_next = 7177;
+    go();
+    exit(0);
+  }
+
+  int st1 = -1;
+  wait(&st1);
+  if(st1 != 0){
+    kill(pid1);
+    kill(pid2);
+  }
+  int st2 = -1;
+  wait(&st2);
+
+  exit(0);
+}