sscanftest.c

/***************************************************************************************
VIRGO - VIRtual Generic Os - linux kernel extensions for cloud 

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

--------------------------------------------------------------------------------------------------
Copyright(C):
Srinivasan Kannan (alias) Ka.Shrinivaasan (alias) Shrinivas Kannan
Independent Open Source Developer, Researcher and Consultant
Ph: 9789346927, 9003082186, 9791165980
Open Source Products Profile(Krishna iResearch): http://sourceforge.net/users/ka_shrinivaasan
Personal website(research): https://sites.google.com/site/kuja27/
emails: ka.shrinivaasan@gmail.com, shrinivas.kannan@gmail.com, kashrinivaasan@live.com
--------------------------------------------------------------------------------------------------

*****************************************************************************************/



#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>

/*

userspace sscanf and vsscanf %p modifier testcase

Outputs:
--------
p=0x8048770, str after sprintf: [0x8048770]
str=[0x8048770], p2 after sscanf: 0x8048770 
after var_sscanf(): str=[0x8048770], p3 after sscanf: 0x8048770 
sizeof(p3) = 4 
lltovoidptr = 0x8048770, data pointed to should be [this is example string] = it is [this is example string]

similar sscanf() works for kernel space in virgo_cloud_mempool_kernelspace.ko 
but doesn't work in virgo_malloc.c and returns null

*/


void var_sscanf(char *str, const char* fmt, ...);

int main()
{
    const char* p="this is example string";
    void* p2;
    void* p3;
    char* endptr;
    char str[300];
    sprintf(str, "%p", p);
    printf("p=%p, str after sprintf: [%s]\n", p, str);
    sscanf(str, "%p", (void**)&p2);
    printf("str=[%s], p2 after sscanf: %p \n", str, p2);
    var_sscanf(str, "%p", (void**)&p3);
    printf("after var_sscanf(): str=[%s], p3 after sscanf: %p \n", str, p3);
    printf("sizeof(p3) = %d \n", sizeof(p3));

    /*
    bit of a hack but a nice one when sscanf() doesn't work the way it is expected to be.
    scan the pointer address in string into a long long and in base 16 and reinterpret cast
    it to void*.
    */  
    long long ll=strtoll(str, &endptr, 16);
    void* lltovoidptr= (void*)ll;
    printf("lltovoidptr = %p, data pointed to should be [%s] = it is [%s]\n", lltovoidptr, p, lltovoidptr); 
    return 0;
}

void var_sscanf(char *str, const char* fmt, ...)
{
    va_list vargs;
    va_start(vargs, fmt);
    vsscanf(str, fmt, vargs);
    va_end(vargs);
}