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"

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);
#pragma GCC diagnostic ignored "-Wstringop-overflow"
    *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();
}