#include "string.h"
#include "errno.h"
#include "sys/types.h"
#include <stdlib.h>

int memcmp(const void *cs, const void *ct, size_t count)
{
    const unsigned char *su1, *su2;
    signed char res = 0;

    for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
    {
        if ((res = *su1 - *su2) != 0)
        {
            break;
        }
    }
    return res;
}

void *memcpy(void *dest, const void *src, size_t count)
{
    char *tmp = (char *)dest;
    const char *s = src;

    while (count--)
        *tmp++ = *s++;

    return dest;
}

int strncmp(const char *cs, const char *ct, size_t count)
{
    register signed char __res = 0;

    while (count)
    {
        if ((__res = *cs - *ct++) != 0 || !*cs++)
        {
            break;
        }
        count--;
    }

    return __res;
}

int strcmp(const char *cs, const char *ct)
{
    register signed char __res;

    while (1)
    {
        if ((__res = *cs - *ct++) != 0 || !*cs++)
        {
            break;
        }
    }

    return __res;
}

char *strcpy(char *dest, const char *src)
{
    char *tmp = dest;

    while ((*dest++ = *src++) != '\0') /* nothing */
        ;
    return tmp;
}

char *strncpy(char *dest, const char *src, size_t count)
{
    char *tmp = dest;

    while (count)
    {
        if ((*dest = *src) != 0)
            src++;
        dest++;
        count--;
    }

    return tmp;
}

void *memset(void *s, int c, size_t count)
{
    char *xs = (char *)s;

    while (count--)
        *xs++ = c;

    return s;
}

size_t strnlen(const char *s, size_t count)
{
    const char *sc;

    for (sc = s; count-- && *sc != '\0'; ++sc)
    {
        /* nothing */}
        return sc - s;
}

char *strcat(char *dest, const char *src)
{
    char *tmp = dest;

    while (*dest)
        dest++;

    while ((*dest++ = *src++) != '\0')
        ;

    return tmp;
}

size_t strlen(const char *s)
{
    const char *sc;

    for (sc = s; *sc != '\0'; ++sc)
    {
        /* nothing */}
        return sc - s;
}

char *strchr(const char *s, int c)
{
    for (; *s != (char)c; ++s)
    {
        if (*s == '\0')
        {
            return NULL;
        }
    }
    return (char *)s;
}

char *strrchr(const char *s, int c)
{
    char *r = NULL;
    for (; *s; ++s)
    {
        if (*s == (char)c)
        {
            r = (char *)s;
        }
    }
    return r;
}

char *strstr(const char *s1, const char *s2)
{
    int l1, l2;

    l2 = strlen(s2);
    if (!l2)
    {
        return (char *)s1;
    }
    l1 = strlen(s1);
    while (l1 >= l2)
    {
        l1--;
        if (!memcmp(s1, s2, l2))
        {
            return (char *)s1;
        }
        s1++;
    }
    return NULL;
}

char *strdup(const char *s)
{
    size_t len = strlen(s) + 1;
    char *str = (char *)malloc(len);
    memcpy(str, s, len);
    return str;
}

/*
 * The following three functions were ripped out of OpenSolaris. Legally, they
 * might have to be in a separate file. Leaving it here out of laziness.
 * Got this from /onnv-gate/usr/src/common/uti/string.c.
 */

char *strpbrk(const char *string, const char *brkset)
{
    const char *p;

    do
    {
        for (p = brkset; *p != '\0' && *p != *string; ++p)
            ;
        if (*p != '\0')
        {
            return ((char *)string);
        }
    } while (*string++);

    return (NULL);
}

size_t strspn(const char *string, const char *charset)
{
    const char *p, *q;

    for (q = string; *q != '\0'; ++q)
    {
        for (p = charset; *p != '\0' && *p != *q; ++p)
            ;
        if (*p == '\0')
        {
            break;
        }
    }

    return (q - string);
}

char *strtok(char *string, const char *sepset)
{
    char *p, *q, *r;
    static char *savept;

    /*
     * Set `p' to our current location in the string.
     */
    p = (string == NULL) ? savept : string;
    if (p == NULL)
    {
        return (NULL);
    }

    /*
     * Skip leading separators; bail if no tokens remain.
     */
    q = p + strspn(p, sepset);
    if (*q == '\0')
    {
        return (NULL);
    }

    /*
     * Mark the end of the token and set `savept' for the next iteration.
     */
    if ((r = strpbrk(q, sepset)) == NULL)
    {
        savept = NULL;
    }
    else
    {
        *r = '\0';
        savept = ++r;
    }

    return (q);
}

/* created with the help of:
 * perl -p -e 's/#define\s+(\w+)\s+\d+\s+\/\* ([^\t\*]+)\s*\*\/\s*$/case $1:
 * return "$2";\n/' < /usr/include/sys/errno.h
 */
char *strerror(int errnum)
{
    switch (errnum)
    {
    case EPERM:
        return "Not super-user";
    case ENOENT:
        return "No such file or directory";
    case ESRCH:
        return "No such process";
    case EINTR:
        return "interrupted system call";
    case EIO:
        return "I/O error";
    case ENXIO:
        return "No such device or address";
    case E2BIG:
        return "Arg list too long";
    case ENOEXEC:
        return "Exec format error";
    case EBADF:
        return "Bad file number";
    case ECHILD:
        return "No children";
    case EAGAIN:
        return "Resource temporarily unavailable";
    case ENOMEM:
        return "Not enough core";
    case EACCES:
        return "Permission denied";
    case EFAULT:
        return "Bad address";
    case ENOTBLK:
        return "Block device required";
    case EBUSY:
        return "Mount device busy";
    case EEXIST:
        return "File exists";
    case EXDEV:
        return "Cross-device link";
    case ENODEV:
        return "No such device";
    case ENOTDIR:
        return "Not a directory";
    case EISDIR:
        return "Is a directory";
    case EINVAL:
        return "Invalid argument";
    case ENFILE:
        return "File table overflow";
    case EMFILE:
        return "Too many open files";
    case ENOTTY:
        return "Inappropriate ioctl for device";
    case ETXTBSY:
        return "Text file busy";
    case EFBIG:
        return "File too large";
    case ENOSPC:
        return "No space left on device";
    case ESPIPE:
        return "Illegal seek";
    case EROFS:
        return "Read only file system";
    case EMLINK:
        return "Too many links";
    case EPIPE:
        return "Broken pipe";
    case EDOM:
        return "Math arg out of domain of func";
    case ERANGE:
        return "Math result not representable";
    case ENOMSG:
        return "No message of desired type";
    case EIDRM:
        return "Identifier removed";
    case ECHRNG:
        return "Channel number out of range";
    case EL2NSYNC:
        return "Level 2 not synchronized";
    case EL3HLT:
        return "Level 3 halted";
    case EL3RST:
        return "Level 3 reset";
    case ELNRNG:
        return "Link number out of range";
    case EUNATCH:
        return "Protocol driver not attached";
    case ENOCSI:
        return "No CSI structure available";
    case EL2HLT:
        return "Level 2 halted";
    case EDEADLK:
        return "Deadlock condition.";
    case ENOLCK:
        return "No record locks available.";
    case ECANCELED:
        return "Operation canceled";
    case ENOTSUP:
        return "Operation not supported";
    case EDQUOT:
        return "Disc quota exceeded";
    case EBADE:
        return "invalid exchange";
    case EBADR:
        return "invalid request descriptor";
    case EXFULL:
        return "exchange full";
    case ENOANO:
        return "no anode";
    case EBADRQC:
        return "invalid request code";
    case EBADSLT:
        return "invalid slot";
    case EBFONT:
        return "bad font file fmt";
    case EOWNERDEAD:
        return "process died with the lock";
    case ENOTRECOVERABLE:
        return "lock is not recoverable";
    case ENOSTR:
        return "Device not a stream";
    case ENODATA:
        return "no data (for no delay io)";
    case ETIME:
        return "timer expired";
    case ENOSR:
        return "out of streams resources";
    case ENONET:
        return "Machine is not on the network";
    case ENOPKG:
        return "Package not installed";
    case EREMOTE:
        return "The object is remote";
    case ENOLINK:
        return "the link has been severed";
    case EADV:
        return "advertise error";
    case ESRMNT:
        return "srmount error";
    case ECOMM:
        return "Communication error on send";
    case EPROTO:
        return "Protocol error";
    case EMULTIHOP:
        return "multihop attempted";
    case EBADMSG:
        return "trying to read unreadable message";
    case ENAMETOOLONG:
        return "path name is too long";
    case EOVERFLOW:
        return "value too large to be stored in data type";
    case ENOTUNIQ:
        return "given log. name not unique";
    case EBADFD:
        return "f.d. invalid for this operation";
    case EREMCHG:
        return "Remote address changed";
    case ELIBACC:
        return "Can't access a needed shared lib.";
    case ELIBBAD:
        return "Accessing a corrupted shared lib.";
    case ELIBSCN:
        return ".lib section in a.out corrupted.";
    case ELIBMAX:
        return "Attempting to link in too many libs.";
    case ELIBEXEC:
        return "Attempting to exec a shared library.";
    case EILSEQ:
        return "Illegal byte sequence.";
    case ENOSYS:
        return "Unsupported file system operation";
    case ELOOP:
        return "Symbolic link loop";
    case ERESTART:
        return "Restartable system call";
    case ESTRPIPE:
        return "if pipe/FIFO, don't sleep in stream head";
    case ENOTEMPTY:
        return "directory not empty";
    case EUSERS:
        return "Too many users (for UFS)";
    case ENOTSOCK:
        return "Socket operation on non-socket";
    case EDESTADDRREQ:
        return "Destination address required";
    case EMSGSIZE:
        return "Message too long";
    case EPROTOTYPE:
        return "Protocol wrong type for socket";
    case ENOPROTOOPT:
        return "Protocol not available";
    case EPROTONOSUPPORT:
        return "Protocol not supported";
    case ESOCKTNOSUPPORT:
        return "Socket type not supported";
    case EPFNOSUPPORT:
        return "Protocol family not supported";
    case EAFNOSUPPORT:
        return "Address family not supported by protocol family";
    case EADDRINUSE:
        return "Address already in use";
    case EADDRNOTAVAIL:
        return "Can't assign requested address";
    case ENETDOWN:
        return "Network is down";
    case ENETUNREACH:
        return "Network is unreachable";
    case ENETRESET:
        return "Network dropped connection because of reset";
    case ECONNABORTED:
        return "Software caused connection abort";
    case ECONNRESET:
        return "Connection reset by peer";
    case ENOBUFS:
        return "No buffer space available";
    case EISCONN:
        return "Socket is already connected";
    case ENOTCONN:
        return "Socket is not connected";
    case ESHUTDOWN:
        return "Can't send after socket shutdown";
    case ETOOMANYREFS:
        return "Too many references: can't splice";
    case ETIMEDOUT:
        return "Connection timed out";
    case ECONNREFUSED:
        return "Connection refused";
    case EHOSTDOWN:
        return "Host is down";
    case EHOSTUNREACH:
        return "No route to host";
    case EALREADY:
        return "operation already in progress";
    case EINPROGRESS:
        return "operation now in progress";
    case ESTALE:
        return "Stale NFS file handle";
    default:
        return 0;
    }
}