--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/usr/usertests.c	Fri May 26 23:11:05 2017 +0900
@@ -0,0 +1,1651 @@
+#include "param.h"
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+#include "fs.h"
+#include "fcntl.h"
+#include "syscall.h"
+#include "memlayout.h"
+
+char buf[8192];
+char name[3];
+char *echoargv[] = { "echo", "ALL", "TESTS", "PASSED", 0 };
+int stdout = 1;
+
+// 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\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;
+    
+		printf(1, "pipe test\n");
+    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;
+        printf(1, "mem test alloc to full\n");
+        while((m2 = malloc(10001)) != 0){
+            *(char**)m2 = m1;
+            m1 = m2;
+        }
+        while(m1){
+            m2 = *(char**)m1;
+            free(m1);
+            m1 = m2;
+        }
+        printf(1, "mem test alloc to full ok\n");
+        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 if (pid < 0) {
+        printf(1, "fork failed!\n");
+    } 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();
+    }
+}
+
+// two processes write two different files at the same
+// time, to test block allocation.
+void
+twofiles(void)
+{
+    int fd, pid, i, j, n, total;
+    char *fname;
+    
+    printf(1, "twofiles test\n");
+    
+    unlink("f1");
+    unlink("f2");
+    
+    pid = fork();
+    if(pid < 0){
+        printf(1, "fork failed\n");
+        exit();
+    }
+    
+    fname = pid ? "f1" : "f2";
+    fd = open(fname, O_CREATE | O_RDWR);
+    if(fd < 0){
+        printf(1, "create failed\n");
+        exit();
+    }
+    
+    memset(buf, pid?'p':'c', 512);
+    for(i = 0; i < 12; i++){
+        if((n = write(fd, buf, 500)) != 500){
+            printf(1, "write failed %d\n", n);
+            exit();
+        }
+    }
+    close(fd);
+    if(pid)
+        wait();
+    else
+        exit();
+    
+    for(i = 0; i < 2; i++){
+        fd = open(i?"f1":"f2", 0);
+        total = 0;
+        while((n = read(fd, buf, sizeof(buf))) > 0){
+            for(j = 0; j < n; j++){
+                if(buf[j] != (i?'p':'c')){
+                    printf(1, "wrong char\n");
+                    exit();
+                }
+            }
+            total += n;
+        }
+        close(fd);
+        if(total != 12*500){
+            printf(1, "wrong length %d\n", total);
+            exit();
+        }
+    }
+    
+    unlink("f1");
+    unlink("f2");
+    
+    printf(1, "twofiles ok\n");
+}
+
+// two processes create and delete different files in same directory
+void
+createdelete(void)
+{
+    enum { N = 20 };
+    int pid, i, fd;
+    char name[32];
+    
+    printf(1, "createdelete test\n");
+    pid = fork();
+    if(pid < 0){
+        printf(1, "fork failed\n");
+        exit();
+    }
+    
+    name[0] = pid ? 'p' : 'c';
+    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();
+            }
+        }
+    }
+    
+    if(pid==0)
+        exit();
+    else
+        wait();
+    
+    for(i = 0; i < N; i++){
+        name[0] = 'p';
+        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);
+        
+        name[0] = 'c';
+        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++){
+        name[0] = 'p';
+        name[1] = '0' + i;
+        unlink(name);
+        name[0] = 'c';
+        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[1], 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)
+{
+}
+
+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");
+}
+
+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));
+    
+    bigargtest();
+    bigwrite();
+    bigargtest();
+    bsstest();
+    sbrktest();
+    validatetest();
+    
+    opentest();
+    writetest();
+    writetest1();
+    createtest();
+    
+    mem();
+    pipe1();
+    //preempt();
+    exitwait();
+    
+    rmdot();
+    fourteen();
+    bigfile();
+    subdir();
+    concreate();
+    linkunlink();
+    linktest();
+    unlinkread();
+    createdelete();
+    twofiles();
+    sharedfd();
+    dirfile();
+    iref();
+    forktest();
+    bigdir(); // slow
+    
+    exectest();
+    
+    exit();
+}