root/compat/snprintf.c

DEFINITIONS

1. git_vsnprintf
2. git_snprintf

#include "../git-compat-util.h"

/*
 * The size parameter specifies the available space, i.e. includes
 * the trailing NUL byte; but Windows's vsnprintf uses the entire
 * buffer and avoids the trailing NUL, should the buffer be exactly
 * big enough for the result. Defining SNPRINTF_SIZE_CORR to 1 will
 * therefore remove 1 byte from the reported buffer size, so we
 * always have room for a trailing NUL byte.
 */
#ifndef SNPRINTF_SIZE_CORR
#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4)
#define SNPRINTF_SIZE_CORR 1
#else
#define SNPRINTF_SIZE_CORR 0
#endif
#endif

#undef vsnprintf
int git_vsnprintf(char *str, size_t maxsize, const char *format, va_list ap)
{
        va_list cp;
        char *s;
        int ret = -1;

        if (maxsize > 0) {
                va_copy(cp, ap);
                ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, cp);
                va_end(cp);
                if (ret == maxsize-1)
                        ret = -1;
                /* Windows does not NUL-terminate if result fills buffer */
                str[maxsize-1] = 0;
        }
        if (ret != -1)
                return ret;

        s = NULL;
        if (maxsize < 128)
                maxsize = 128;

        while (ret == -1) {
                maxsize *= 4;
                str = realloc(s, maxsize);
                if (! str)
                        break;
                s = str;
                va_copy(cp, ap);
                ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, cp);
                va_end(cp);
                if (ret == maxsize-1)
                        ret = -1;
        }
        free(s);
        return ret;
}

int git_snprintf(char *str, size_t maxsize, const char *format, ...)
{
        va_list ap;
        int ret;

        va_start(ap, format);
        ret = git_vsnprintf(str, maxsize, format, ap);
        va_end(ap);

        return ret;
}