qt-everywhere-src-5.15.1/qtbase/src/corelib/text/qvsnprintf.cpp

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#include "qplatformdefs.h"

#include "qbytearray.h"
#include "qstring.h"

#include "string.h"

QT_BEGIN_NAMESPACE

#if !defined(QT_VSNPRINTF) || defined(Q_CLANG_QDOC)

/*!
    \relates QByteArray

    A portable \c vsnprintf() function. Will call \c ::vsnprintf(), \c
    ::_vsnprintf(), or \c ::vsnprintf_s depending on the system, or
    fall back to an internal version.

    \a fmt is the \c printf() format string. The result is put into
    \a str, which is a buffer of at least \a n bytes.

    The caller is responsible to call \c va_end() on \a ap.

    \warning Since vsnprintf() shows different behavior on certain
    platforms, you should not rely on the return value or on the fact
    that you will always get a 0 terminated string back.

    Ideally, you should never call this function but use QString::asprintf()
    instead.

    \sa qsnprintf(), QString::asprintf()
*/

int qvsnprintf(char *str, size_t n, const char *fmt, va_list ap)
{
    if (!str || !fmt)
        return -1;

    const QByteArray ba = QString::vasprintf(fmt, ap).toLocal8Bit();

    if (n > 0) {
        size_t blen = qMin(size_t(ba.length()), size_t(n - 1));
        memcpy(str, ba.constData(), blen);
        str[blen] = '\0'; // make sure str is always 0 terminated
    }

    return ba.length();
}

#else

QT_BEGIN_INCLUDE_NAMESPACE
#include <stdio.h>
QT_END_INCLUDE_NAMESPACE

int qvsnprintf(char *str, size_t n, const char *fmt, va_list ap)
{
    return QT_VSNPRINTF(str, n, fmt, ap);
}

#endif

/*!
    \target bytearray-qsnprintf
    \relates QByteArray

    A portable snprintf() function, calls qvsnprintf.

    \a fmt is the \c printf() format string. The result is put into
    \a str, which is a buffer of at least \a n bytes.

    \warning Call this function only when you know what you are doing
    since it shows different behavior on certain platforms.
    Use QString::asprintf() to format a string instead.

    \sa qvsnprintf(), QString::asprintf()
*/

int qsnprintf(char *str, size_t n, const char *fmt, ...)
{
    va_list ap;
    va_start(ap, fmt);

    int ret = qvsnprintf(str, n, fmt, ap);
    va_end(ap);

    return ret;
}

QT_END_NAMESPACE