qbytearray.cpp

奇趣公司比较新的qt/emd版本

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#include "qbytearray.h"
#include "qbytearraymatcher.h"
#include "qtools_p.h"
#include "qstring.h"
#include "qlist.h"
#include "qlocale.h"
#include "qlocale_p.h"
#include "qunicodetables_p.h"
#ifndef QT_NO_DATASTREAM
#include <qdatastream.h>
#endif

#ifndef QT_NO_COMPRESS
#include <zlib.h>
#endif
#include <ctype.h>
#include <limits.h>
#include <string.h>

int qAllocMore(int alloc, int extra)
{
    const int page = 1 << 12;
    int nalloc;
    alloc += extra;
    if (alloc < 1<<6) {
        nalloc = (1<<3) + ((alloc >>3) << 3);
    } else  {
        nalloc = (alloc < page) ? 1 << 3 : page;
        while (nalloc < alloc) {
            if (nalloc <= 0)
                return INT_MAX;
            nalloc *= 2;
        }
    }
    return nalloc - extra;
}

/*****************************************************************************
  Safe and portable C string functions; extensions to standard string.h
 *****************************************************************************/

/*! \relates QByteArray

    Returns a duplicate string.

    Allocates space for a copy of \a src, copies it, and returns a
    pointer to the copy. If \a src is 0, it immediately returns 0.

    Ownership is passed to the caller, so the returned string must be
    deleted using \c delete[].
*/

char *qstrdup(const char *src)
{
    if (!src)
        return 0;
    char *dst = new char[strlen(src) + 1];
    return qstrcpy(dst, src);
}

/*! \relates QByteArray

    Copies all the characters up to and including the '\\0' from \a
    src into \a dst and returns a pointer to \a dst. If \a src is 0,
    it immediately returns 0.

    This function assumes that \a dst is large enough to hold the
    contents of \a src.

    \sa qstrncpy()
*/

char *qstrcpy(char *dst, const char *src)
{
    if (!src)
        return 0;
#if defined(_MSC_VER) && _MSC_VER >= 1400
    int len = qstrlen(src);
	// This is actually not secure!!! It will be fixed
	// properly in a later release!
    if (len >= 0 && strcpy_s(dst, len+1, src) == 0)
	    return dst;
    return 0;
#else
    return strcpy(dst, src);
#endif
}

/*! \relates QByteArray

    A safe \c strncpy() function.

    Copies at most \a len bytes from \a src (stopping at \a len or the
    terminating '\\0' whichever comes first) into \a dst and returns a
    pointer to \a dst. Guarantees that \a dst is '\\0'-terminated. If
    \a src or \a dst is 0, returns 0 immediately.

    This function assumes that \a dst is at least \a len characters
    long.

    \sa qstrcpy()
*/

char *qstrncpy(char *dst, const char *src, uint len)
{
    if (!src || !dst)
        return 0;
#if defined(_MSC_VER) && _MSC_VER >= 1400
	strncpy_s(dst, len, src, len-1);
#else
    strncpy(dst, src, len);
#endif
    if (len > 0)
        dst[len-1] = '\0';
    return dst;
}

/*! \fn uint qstrlen(const char *str)
    \relates QByteArray

    A safe \c strlen() function.

    Returns the number of characters that precede the terminating '\\0',
    or 0 if \a str is 0.

    \sa qstrnlen()
*/

/*! \fn uint qstrnlen(const char *str, uint maxlen)
    \relates QByteArray
    \since 4.2

    A safe \c strnlen() function.

    Returns the number of characters that precede the terminating '\\0', but
    at most \a maxlen. If \a str is 0, returns 0.

    \sa qstrlen()
*/

/*! 
    \relates QByteArray

    A safe \c strcmp() function.

    Compares \a str1 and \a str2. Returns a negative value if \a str1
    is less than \a str2, 0 if \a str1 is equal to \a str2 or a
    positive value if \a str1 is greater than \a str2.

    Special case 1: Returns 0 if \a str1 and \a str2 are both 0.

    Special case 2: Returns an arbitrary non-zero value if \a str1 is 0
    or \a str2 is 0 (but not both).

    \sa qstrncmp(), qstricmp(), qstrnicmp(), {Note on 8-bit character comparisons}
*/
int qstrcmp(const char *str1, const char *str2)
{
    return (str1 && str2) ? strcmp(str1, str2)
        : (str1 ? 1 : (str2 ? -1 : 0));
}

/*! \fn int qstrncmp(const char *str1, const char *str2, uint len);

    \relates QByteArray

    A safe \c strncmp() function.

    Compares at most \a len bytes of \a str1 and \a str2.

    Returns a negative value if \a str1 is less than \a str2, 0 if \a
    str1 is equal to \a str2 or a positive value if \a str1 is greater
    than \a str2.

    Special case 1: Returns 0 if \a str1 and \a str2 are both 0.

    Special case 2: Returns a random non-zero value if \a str1 is 0
    or \a str2 is 0 (but not both).

    \sa qstrcmp(), qstricmp(), qstrnicmp(),
        {Note on 8-bit character comparisons}
*/

/*! \relates QByteArray

    A safe \c stricmp() function.

    Compares \a str1 and \a str2 ignoring the case of the
    characters. The encoding of the strings is assumed to be Latin-1.

    Returns a negative value if \a str1 is less than \a str2, 0 if \a
    str1 is equal to \a str2 or a positive value if \a str1 is greater
    than \a str2.

    Special case 1: Returns 0 if \a str1 and \a str2 are both 0.

    Special case 2: Returns a random non-zero value if \a str1 is 0
    or \a str2 is 0 (but not both).

    \sa qstrcmp(), qstrncmp(), qstrnicmp(),
        {Note on 8-bit character comparisons}
*/

int qstricmp(const char *str1, const char *str2)
{
    register const uchar *s1 = reinterpret_cast<const uchar *>(str1);
    register const uchar *s2 = reinterpret_cast<const uchar *>(str2);
    int res;
    uchar c;
    if (!s1 || !s2)
        return s1 ? 1 : (s2 ? -1 : 0);
    for (; !(res = (c = QChar::toLower((ushort)*s1)) - QChar::toLower((ushort)*s2)); s1++, s2++)
        if (!c)                                // strings are equal
            break;
    return res;
}

/*! \relates QByteArray

    A safe \c strnicmp() function.

    Compares at most \a len bytes of \a str1 and \a str2 ignoring the
    case of the characters. The encoding of the strings is assumed to
    be Latin-1.

    Returns a negative value if \a str1 is less than \a str2, 0 if \a str1
    is equal to \a str2 or a positive value if \a str1 is greater than \a
    str2.

    Special case 1: Returns 0 if \a str1 and \a str2 are both 0.

    Special case 2: Returns a random non-zero value if \a str1 is 0
    or \a str2 is 0 (but not both).

    \sa qstrcmp(), qstrncmp(), qstricmp(),
        {Note on 8-bit character comparisons}
*/

int qstrnicmp(const char *str1, const char *str2, uint len)
{
    register const uchar *s1 = reinterpret_cast<const uchar *>(str1);
    register const uchar *s2 = reinterpret_cast<const uchar *>(str2);
    int res;
    uchar c;
    if (!s1 || !s2)
        return s1 ? 1 : (s2 ? -1 : 0);
    for (; len--; s1++, s2++) {
        if ((res = (c = QChar::toLower((ushort)*s1)) - QChar::toLower((ushort)*s2)))
            return res;
        if (!c)                                // strings are equal
            break;
    }
    return 0;
}

// the CRC table below is created by the following piece of code
#if 0
static void createCRC16Table()                        // build CRC16 lookup table
{
    register unsigned int i;
    register unsigned int j;
    unsigned short crc_tbl[16];
    unsigned int v0, v1, v2, v3;
    for (i = 0; i < 16; i++) {
        v0 = i & 1;
        v1 = (i >> 1) & 1;
        v2 = (i >> 2) & 1;
        v3 = (i >> 3) & 1;
        j = 0;
#undef SET_BIT
#define SET_BIT(x, b, v) (x) |= (v) << (b)
        SET_BIT(j,  0, v0);
        SET_BIT(j,  7, v0);
        SET_BIT(j, 12, v0);
        SET_BIT(j,  1, v1);
        SET_BIT(j,  8, v1);
        SET_BIT(j, 13, v1);
        SET_BIT(j,  2, v2);
        SET_BIT(j,  9, v2);
        SET_BIT(j, 14, v2);
        SET_BIT(j,  3, v3);
        SET_BIT(j, 10, v3);
        SET_BIT(j, 15, v3);
        crc_tbl[i] = j;
    }
    printf("static const quint16 crc_tbl[16] = {\n");
    for (int i = 0; i < 16; i +=4)
        printf("    0x%04x, 0x%04x, 0x%04x, 0x%04x,\n", crc_tbl[i], crc_tbl[i+1], crc_tbl[i+2], crc_tbl[i+3]);
    printf("};\n");
}
#endif

static const quint16 crc_tbl[16] = {
    0x0000, 0x1081, 0x2102, 0x3183,
    0x4204, 0x5285, 0x6306, 0x7387,
    0x8408, 0x9489, 0xa50a, 0xb58b,
    0xc60c, 0xd68d, 0xe70e, 0xf78f
};

/*! \relates QByteArray

    Returns the CRC-16 checksum of the first \a len bytes of \a data.

    The checksum is independent of the byte order (endianness).
*/

quint16 qChecksum(const char *data, uint len)
{
    register quint16 crc = 0xffff;
    uchar c;
    const uchar *p = reinterpret_cast<const uchar *>(data);
    while (len--) {
        c = *p++;
        crc = ((crc >> 4) & 0x0fff) ^ crc_tbl[((crc ^ c) & 15)];
        c >>= 4;
        crc = ((crc >> 4) & 0x0fff) ^ crc_tbl[((crc ^ c) & 15)];
    }
    return ~crc & 0xffff;
}

/*! \fn QByteArray qCompress(const QByteArray& data, int compressionLevel)

    \relates QByteArray

    Compresses the \a data byte array and returns the compressed data
    in a new byte array.

    The \a compressionLevel parameter specifies how much compression
    should be used. Valid values are between 0 and 9, with 9
    corresponding to the greatest compression (i.e. smaller compressed
    data) at the cost of using a slower algorithm. Smaller values (8,
    7, ..., 1) provide successively less compression at slightly
    faster speeds. The value 0 corresponds to no compression at all.
    The default value is -1, which specifies zlib's default
    compression.

    \sa qUncompress()
*/

/*! \relates QByteArray

    \overload

    Compresses the first \a nbytes of \a data and returns the
    compressed data in a new byte array.
*/

#ifndef QT_NO_COMPRESS
QByteArray qCompress(const uchar* data, int nbytes, int compressionLevel)
{
    if (nbytes == 0) {
        return QByteArray(4, '\0');
    }
    if (!data) {
        qWarning("qCompress: Data is null");
        return QByteArray();
    }
    if (compressionLevel < -1 || compressionLevel > 9)
        compressionLevel = -1;

    ulong len = nbytes + nbytes / 100 + 13;
    QByteArray bazip;
    int res;
    do {
        bazip.resize(len + 4);
        res = ::compress2((uchar*)bazip.data()+4, &len, (uchar*)data, nbytes, compressionLevel);

        switch (res) {
        case Z_OK:
            bazip.resize(len + 4);
            bazip[0] = (nbytes & 0xff000000) >> 24;
            bazip[1] = (nbytes & 0x00ff0000) >> 16;
            bazip[2] = (nbytes & 0x0000ff00) >> 8;
            bazip[3] = (nbytes & 0x000000ff);
            break;
        case Z_MEM_ERROR:
            qWarning("qCompress: Z_MEM_ERROR: Not enough memory");
            bazip.resize(0);
            break;
        case Z_BUF_ERROR:
            len *= 2;
            break;
        }
    } while (res == Z_BUF_ERROR);

    return bazip;
}
#endif

/*!
    \fn QByteArray qUncompress(const QByteArray& data)

    \relates QByteArray

    Uncompresses the \a data byte array and returns a new byte array
    with the uncompressed data.

    Returns an empty QByteArray if the input data was corrupt.

    This function will uncompress data compressed with qCompress()
    from this and any earlier Qt version, back to Qt 3.1 when this
    feature was added.

    \bold{Note:} If you want to use this function to uncompress external
    data compressed using zlib, you first need to prepend four bytes to the
    byte array that contain the expected length of the uncompressed data
    encoded in big-endian order (most significant byte first).

    \sa qCompress()
*/

/*! \relates QByteArray

    \overload

    Uncompresses the first \a nbytes of \a data and returns a new byte
    array with the uncompressed data.
*/

#ifndef QT_NO_COMPRESS
QByteArray qUncompress(const uchar* data, int nbytes)
{
    if (!data) {
        qWarning("qUncompress: Data is null");
        return QByteArray();
    }
    if (nbytes <= 4) {
        if (nbytes < 4 || (data[0]!=0 || data[1]!=0 || data[2]!=0 || data[3]!=0))
            qWarning("qUncompress: Input data is corrupted");
        return QByteArray();
    }
    ulong expectedSize = (data[0] << 24) | (data[1] << 16) |
                       (data[2] <<  8) | (data[3]      );
    ulong len = qMax(expectedSize, 1ul);