usertests.c

#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"

#define NULL 0

// exit and wait calls were modified for CS153

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(1);
    }
    if(chdir("iputdir") < 0){
        printf(stdout, "chdir iputdir failed\n");
        exit(1);
    }
    if(unlink("../iputdir") < 0){
        printf(stdout, "unlink ../iputdir failed\n");
        exit(1);
    }
    if(chdir("/") < 0){
        printf(stdout, "chdir / failed\n");
        exit(1);
    }
    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(1);
    }
    if(pid == 0){
        if(mkdir("iputdir") < 0){
            printf(stdout, "mkdir failed\n");
            exit(1);
        }
        if(chdir("iputdir") < 0){
            printf(stdout, "child chdir failed\n");
            exit(1);
        }
        if(unlink("../iputdir") < 0){
            printf(stdout, "unlink ../iputdir failed\n");
            exit(1);
        }
        exit(0);
    }
    wait(&pid);
    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(1);
    }
    pid = fork();
    if(pid < 0){
        printf(stdout, "fork failed\n");
        exit(1);
    }
    if(pid == 0){
        int fd = open("oidir", O_RDWR);
        if(fd >= 0){
            printf(stdout, "open directory for write succeeded\n");
            exit(0);
        }
        exit(0);
    }
    sleep(1);
    if(unlink("oidir") != 0){
        printf(stdout, "unlink failed\n");
        exit(1);
    }
    wait(&pid);
    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(1);
    }
    close(fd);
    fd = open("doesnotexist", 0);
    if(fd >= 0){
        printf(stdout, "open doesnotexist succeeded!\n");
        exit(0);
    }
    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(1);
    }
    for(i = 0; i < 100; i++){
        if(write(fd, "aaaaaaaaaa", 10) != 10){
            printf(stdout, "error: write aa %d new file failed\n", i);
            exit(1);
        }
        if(write(fd, "bbbbbbbbbb", 10) != 10){
            printf(stdout, "error: write bb %d new file failed\n", i);
            exit(1);
        }
    }
    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(1);
    }
    i = read(fd, buf, 2000);
    if(i == 2000){
        printf(stdout, "read succeeded ok\n");
    } else {
        printf(stdout, "read failed\n");
        exit(1);
    }
    close(fd);

    if(unlink("small") < 0){
        printf(stdout, "unlink small failed\n");
        exit(1);
    }
    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(1);
    }

    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(1);
        }
    }

    close(fd);

    fd = open("big", O_RDONLY);
    if(fd < 0){
        printf(stdout, "error: open big failed!\n");
        exit(1);
    }

    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(0);
            }
            break;
        } else if(i != 512){
            printf(stdout, "read failed %d\n", i);
            exit(1);
        }
        if(((int*)buf)[0] != n){
            printf(stdout, "read content of block %d is %d\n",
                    n, ((int*)buf)[0]);
            exit(0);
        }
        n++;
    }
    close(fd);
    if(unlink("big") < 0){
        printf(stdout, "unlink big failed\n");
        exit(1);
    }
    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(1);
    }

    if(chdir("dir0") < 0){
        printf(stdout, "chdir dir0 failed\n");
        exit(1);
    }

    if(chdir("..") < 0){
        printf(stdout, "chdir .. failed\n");
        exit(1);
    }

    if(unlink("dir0") < 0){
        printf(stdout, "unlink dir0 failed\n");
        exit(1);
    }
    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(1);
    }
}

// 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(1);
    }
    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(1);
            }
        }
        exit(0);
    } 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(1);
        }
        close(fds[0]);
        wait(&pid);
    } else {
        printf(1, "fork() failed\n");
        exit(1);
    }
    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(NULL);
    wait(NULL);
    wait(NULL);
    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) != pid){
                printf(1, "wait wrong pid\n");
                return;
            }
        } else {
            exit(1);
        }
    }
    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(1);
        }
        free(m1);
        printf(1, "mem ok\n");
        exit(0);
    } else {
        wait(&pid);
    }
}

// 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(1);
    else
        wait(&pid);
    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(1);
    }
}

// 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(1);
        }

        if(pid == 0){
            fd = open(fname, O_CREATE | O_RDWR);
            if(fd < 0){
                printf(1, "create failed\n");
                exit(1);
            }

            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(1);
                }
            }
            exit(0);
        }
    }

    for(pi = 0; pi < 4; pi++){
        wait(&pid);
    }

    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(1);
                }
            }
            total += n;
        }
        close(fd);
        if(total != 12*500){
            printf(1, "wrong length %d\n", total);
            exit(1);
        }
        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(1);
        }

        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(1);
                }
                close(fd);
                if(i > 0 && (i % 2 ) == 0){
                    name[1] = '0' + (i / 2);
                    if(unlink(name) < 0){
                        printf(1, "unlink failed\n");
                        exit(1);
                    }
                }
            }
            exit(0);
        }
    }

    for(pi = 0; pi < 4; pi++){
        wait(&pid);
    }

    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(1);
            } else if((i >= 1 && i < N/2) && fd >= 0){
                printf(1, "oops createdelete %s did exist\n", name);
                exit(1);
            }
            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(1);
    }
    write(fd, "hello", 5);
    close(fd);

    fd = open("unlinkread", O_RDWR);
    if(fd < 0){
        printf(1, "open unlinkread failed\n");
        exit(1);
    }
    if(unlink("unlinkread") != 0){
        printf(1, "unlink unlinkread failed\n");
        exit(1);
    }

    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(1);
    }
    if(buf[0] != 'h'){
        printf(1, "unlinkread wrong data\n");
        exit(1);
    }
    if(write(fd, buf, 10) != 10){
        printf(1, "unlinkread write failed\n");
        exit(1);
    }
    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(1);
    }
    if(write(fd, "hello", 5) != 5){
        printf(1, "write lf1 failed\n");
        exit(1);
    }
    close(fd);

    if(link("lf1", "lf2") < 0){
        printf(1, "link lf1 lf2 failed\n");
        exit(1);
    }
    unlink("lf1");

    if(open("lf1", 0) >= 0){
        printf(1, "unlinked lf1 but it is still there!\n");
        exit(1);
    }

    fd = open("lf2", 0);
    if(fd < 0){
        printf(1, "open lf2 failed\n");
        exit(1);
    }
    if(read(fd, buf, sizeof(buf)) != 5){
        printf(1, "read lf2 failed\n");
        exit(1);
    }
    close(fd);

    if(link("lf2", "lf2") >= 0){
        printf(1, "link lf2 lf2 succeeded! oops\n");
        exit(0);
    }

    unlink("lf2");
    if(link("lf2", "lf1") >= 0){
        printf(1, "link non-existant succeeded! oops\n");
        exit(0);
    }

    if(link(".", "lf1") >= 0){
        printf(1, "link . lf1 succeeded! oops\n");
        exit(0);
    }

    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(1);
            }
            close(fd);
        }
        if(pid == 0)
            exit(0);
        else
            wait(&pid);
    }

    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(1);
            }
            if(fa[i]){
                printf(1, "concreate duplicate file %s\n", de.name);
                exit(1);
            }
            fa[i] = 1;
            n++;
        }
    }
    close(fd);

    if(n != 40){
        printf(1, "concreate not enough files in directory listing\n");
        exit(1);
    }

    for(i = 0; i < 40; i++){
        file[1] = '0' + i;
        pid = fork();
        if(pid < 0){
            printf(1, "fork failed\n");
            exit(1);
        }
        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(0);
        else
            wait(&pid);
    }

    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(1);
    }

    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(&pid);
    else
        exit(0);

    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(1);
    }
    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(1);
        }
    }

    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(1);
        }
    }

    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(1);
    }

    fd = open("dd/ff", O_CREATE | O_RDWR);
    if(fd < 0){
        printf(1, "create dd/ff failed\n");
        exit(1);
    }
    write(fd, "ff", 2);
    close(fd);

    if(unlink("dd") >= 0){
        printf(1, "unlink dd (non-empty dir) succeeded!\n");
        exit(0);
    }

    if(mkdir("/dd/dd") != 0){
        printf(1, "subdir mkdir dd/dd failed\n");
        exit(1);
    }

    fd = open("dd/dd/ff", O_CREATE | O_RDWR);
    if(fd < 0){
        printf(1, "create dd/dd/ff failed\n");
        exit(1);
    }
    write(fd, "FF", 2);
    close(fd);

    fd = open("dd/dd/../ff", 0);
    if(fd < 0){
        printf(1, "open dd/dd/../ff failed\n");
        exit(0);
    }
    cc = read(fd, buf, sizeof(buf));
    if(cc != 2 || buf[0] != 'f'){
        printf(1, "dd/dd/../ff wrong content\n");
        exit(1);
    }
    close(fd);

    if(link("dd/dd/ff", "dd/dd/ffff") != 0){
        printf(1, "link dd/dd/ff dd/dd/ffff failed\n");
        exit(1);
    }

    if(unlink("dd/dd/ff") != 0){
        printf(1, "unlink dd/dd/ff failed\n");
        exit(1);
    }
    if(open("dd/dd/ff", O_RDONLY) >= 0){
        printf(1, "open (unlinked) dd/dd/ff succeeded\n");
        exit(0);
    }

    if(chdir("dd") != 0){
        printf(1, "chdir dd failed\n");
        exit(1);
    }
    if(chdir("dd/../../dd") != 0){
        printf(1, "chdir dd/../../dd failed\n");
        exit(1);
    }
    if(chdir("dd/../../../dd") != 0){
        printf(1, "chdir dd/../../dd failed\n");
        exit(1);
    }
    if(chdir("./..") != 0){
        printf(1, "chdir ./.. failed\n");
        exit(1);
    }

    fd = open("dd/dd/ffff", 0);
    if(fd < 0){
        printf(1, "open dd/dd/ffff failed\n");
        exit(1);
    }
    if(read(fd, buf, sizeof(buf)) != 2){
        printf(1, "read dd/dd/ffff wrong len\n");
        exit(1);
    }
    close(fd);

    if(open("dd/dd/ff", O_RDONLY) >= 0){
        printf(1, "open (unlinked) dd/dd/ff succeeded!\n");
        exit(0);
    }

    if(open("dd/ff/ff", O_CREATE|O_RDWR) >= 0){
        printf(1, "create dd/ff/ff succeeded!\n");
        exit(0);
    }
    if(open("dd/xx/ff", O_CREATE|O_RDWR) >= 0){
        printf(1, "create dd/xx/ff succeeded!\n");
        exit(0);
    }
    if(open("dd", O_CREATE) >= 0){
        printf(1, "create dd succeeded!\n");
        exit(0);
    }
    if(open("dd", O_RDWR) >= 0){
        printf(1, "open dd rdwr succeeded!\n");
        exit(0);
    }
    if(open("dd", O_WRONLY) >= 0){
        printf(1, "open dd wronly succeeded!\n");
        exit(0);
    }
    if(link("dd/ff/ff", "dd/dd/xx") == 0){
        printf(1, "link dd/ff/ff dd/dd/xx succeeded!\n");
        exit(0);
    }
    if(link("dd/xx/ff", "dd/dd/xx") == 0){
        printf(1, "link dd/xx/ff dd/dd/xx succeeded!\n");
        exit(0);
    }
    if(link("dd/ff", "dd/dd/ffff") == 0){
        printf(1, "link dd/ff dd/dd/ffff succeeded!\n");
        exit(0);
    }
    if(mkdir("dd/ff/ff") == 0){
        printf(1, "mkdir dd/ff/ff succeeded!\n");
        exit(0);
    }
    if(mkdir("dd/xx/ff") == 0){
        printf(1, "mkdir dd/xx/ff succeeded!\n");
        exit(0);
    }
    if(mkdir("dd/dd/ffff") == 0){
        printf(1, "mkdir dd/dd/ffff succeeded!\n");
        exit(0);
    }
    if(unlink("dd/xx/ff") == 0){
        printf(1, "unlink dd/xx/ff succeeded!\n");
        exit(0);
    }
    if(unlink("dd/ff/ff") == 0){
        printf(1, "unlink dd/ff/ff succeeded!\n");
        exit(0);
    }
    if(chdir("dd/ff") == 0){
        printf(1, "chdir dd/ff succeeded!\n");
        exit(0);
    }
    if(chdir("dd/xx") == 0){
        printf(1, "chdir dd/xx succeeded!\n");
        exit(0);
    }

    if(unlink("dd/dd/ffff") != 0){
        printf(1, "unlink dd/dd/ff failed\n");
        exit(1);
    }
    if(unlink("dd/ff") != 0){
        printf(1, "unlink dd/ff failed\n");
        exit(1);
    }
    if(unlink("dd") == 0){
        printf(1, "unlink non-empty dd succeeded!\n");
        exit(0);
    }
    if(unlink("dd/dd") < 0){
        printf(1, "unlink dd/dd failed\n");
        exit(1);
    }
    if(unlink("dd") < 0){
        printf(1, "unlink dd failed\n");
        exit(1);
    }

    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(1);
        }
        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(0);
            }
        }
        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(1);
    }
    for(i = 0; i < 20; i++){
        memset(buf, i, 600);
        if(write(fd, buf, 600) != 600){
            printf(1, "write bigfile failed\n");
            exit(1);
        }
    }
    close(fd);

    fd = open("bigfile", 0);
    if(fd < 0){
        printf(1, "cannot open bigfile\n");
        exit(1);
    }
    total = 0;
    for(i = 0; ; i++){
        cc = read(fd, buf, 300);
        if(cc < 0){
            printf(1, "read bigfile failed\n");
            exit(1);
        }
        if(cc == 0)
            break;
        if(cc != 300){
            printf(1, "short read bigfile\n");
            exit(1);
        }
        if(buf[0] != i/2 || buf[299] != i/2){
            printf(1, "read bigfile wrong data\n");
            exit(1);
        }
        total += cc;
    }
    close(fd);
    if(total != 20*600){
        printf(1, "read bigfile wrong total\n");
        exit(1);
    }
    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(1);
    }
    if(mkdir("12345678901234/123456789012345") != 0){
        printf(1, "mkdir 12345678901234/123456789012345 failed\n");
        exit(1);
    }
    fd = open("123456789012345/123456789012345/123456789012345", O_CREATE);
    if(fd < 0){
        printf(1, "create 123456789012345/123456789012345/123456789012345 failed\n");
        exit(1);
    }
    close(fd);
    fd = open("12345678901234/12345678901234/12345678901234", 0);
    if(fd < 0){
        printf(1, "open 12345678901234/12345678901234/12345678901234 failed\n");
        exit(1);
    }
    close(fd);

    if(mkdir("12345678901234/12345678901234") == 0){
        printf(1, "mkdir 12345678901234/12345678901234 succeeded!\n");
        exit(0);
    }
    if(mkdir("123456789012345/12345678901234") == 0){
        printf(1, "mkdir 12345678901234/123456789012345 succeeded!\n");
        exit(0);
    }

    printf(1, "fourteen ok\n");
}

    void
rmdot(void)
{
    printf(1, "rmdot test\n");
    if(mkdir("dots") != 0){
        printf(1, "mkdir dots failed\n");
        exit(1);
    }
    if(chdir("dots") != 0){
        printf(1, "chdir dots failed\n");
        exit(1);
    }
    if(unlink(".") == 0){
        printf(1, "rm . worked!\n");
        exit(0);
    }
    if(unlink("..") == 0){
        printf(1, "rm .. worked!\n");
        exit(0);
    }
    if(chdir("/") != 0){
        printf(1, "chdir / failed\n");
        exit(1);
    }
    if(unlink("dots/.") == 0){
        printf(1, "unlink dots/. worked!\n");
        exit(0);
    }
    if(unlink("dots/..") == 0){
        printf(1, "unlink dots/.. worked!\n");
        exit(0);
    }
    if(unlink("dots") != 0){
        printf(1, "unlink dots failed!\n");
        exit(1);
    }
    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(1);
    }
    close(fd);
    if(chdir("dirfile") == 0){
        printf(1, "chdir dirfile succeeded!\n");
        exit(0);
    }
    fd = open("dirfile/xx", 0);
    if(fd >= 0){
        printf(1, "create dirfile/xx succeeded!\n");
        exit(0);
    }
    fd = open("dirfile/xx", O_CREATE);
    if(fd >= 0){
        printf(1, "create dirfile/xx succeeded!\n");
        exit(0);
    }
    if(mkdir("dirfile/xx") == 0){
        printf(1, "mkdir dirfile/xx succeeded!\n");
        exit(0);
    }
    if(unlink("dirfile/xx") == 0){
        printf(1, "unlink dirfile/xx succeeded!\n");
        exit(0);
    }
    if(link("README", "dirfile/xx") == 0){
        printf(1, "link to dirfile/xx succeeded!\n");
        exit(0);
    }
    if(unlink("dirfile") != 0){
        printf(1, "unlink dirfile failed!\n");
        exit(1);
    }

    fd = open(".", O_RDWR);
    if(fd >= 0){
        printf(1, "open . for writing succeeded!\n");
        exit(0);
    }
    fd = open(".", 0);
    if(write(fd, "x", 1) > 0){
        printf(1, "write . succeeded!\n");
        exit(0);
    }
    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(1);
        }
        if(chdir("irefd") != 0){
            printf(1, "chdir irefd failed\n");
            exit(1);
        }

        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(0);
    }

    if(n == 1000){
        printf(1, "fork claimed to work 1000 times!\n");
        exit(1);
    }

    for(; n > 0; n--){
        if(wait(&pid) < 0){
            printf(1, "wait stopped early\n");
            exit(0);
        }
    }

    if(wait(&pid) != -1){
        printf(1, "wait got too many\n");
        exit(1);
    }

    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(1);
        }
        *b = 1;
        a = b + 1;
    }
    pid = fork();
    if(pid < 0){
        printf(stdout, "sbrk test fork failed\n");
        exit(1);
    }
    c = sbrk(1);
    c = sbrk(1);
    if(c != a + 1){
        printf(stdout, "sbrk test failed post-fork\n");
        exit(1);
    }
    if(pid == 0)
        exit(0);
    wait(&pid);

    // 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(1);
    }
    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(1);
    }
    c = sbrk(0);
    if(c != a - 4096){
        printf(stdout, "sbrk deallocation produced wrong address, a %x c %x\n", a, c);
        exit(1);
    }

    // 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(1);
    }
    if(*lastaddr == 99){
        // should be zero
        printf(stdout, "sbrk de-allocation didn't really deallocate\n");
        exit(1);
    }

    a = sbrk(0);
    c = sbrk(-(sbrk(0) - oldbrk));
    if(c != a){
        printf(stdout, "sbrk downsize failed, a %x c %x\n", a, c);
        exit(1);
    }

    // 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(1);
        }
        if(pid == 0){
            printf(stdout, "oops could read %x = %x\n", a, *a);
            kill(ppid);
            exit(0);
        }
        wait(&pid);
    }

    // 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(1);
    }
    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(&pid);
    }
    if(c == (char*)0xffffffff){
        printf(stdout, "failed sbrk leaked memory\n");
        exit(1);
    }

    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(1);
        }
        sleep(0);
        sleep(0);
        kill(pid);
        wait(&pid);

        // 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(1);
        }
    }

    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(1);
        }
    }
    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(0);
    } else if(pid < 0){
        printf(stdout, "bigargtest: fork failed\n");
        exit(1);
    }
    wait(&pid);
    fd = open("bigarg-ok", 0);
    if(fd < 0){
        printf(stdout, "bigarg test failed!\n");
        exit(1);
    }
    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(1);
    } else if(pid < 0){
        printf (1, "fork failed\n");
        exit(1);
    }
    wait(&pid);
    printf(1, "uio test done\n");
}

void argptest()
{
    int fd;
    fd = open("init", O_RDONLY);
    if (fd < 0) {
        printf(2, "open failed\n");
        exit(1);
    }
    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(1);
    }
    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(0);
    return 0;
}