check_png.cpp

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/***************************************
        Auteur : Pierre Aubert
        Mail : pierre.aubert@lapp.in2p3.fr
        Licence : CeCILL-C
****************************************/
 
#include <stdio.h>
#include "check_png.h"
 
#define PNG_BYTES_TO_CHECK 4


bool check_is_png(const PPath & fileName){
        unsigned char buf[PNG_BYTES_TO_CHECK];
 
        FILE * fp = fopen(fileName.c_str(), "rb");
        /* Open the prospective PNG file. */
        if(fp == NULL){return false;}
 
        /* Read in some of the signature bytes. */
        if(fread(buf, 1, PNG_BYTES_TO_CHECK, fp) != PNG_BYTES_TO_CHECK){
                fclose(fp);
                return false;
        }
        /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature.
        * Return nonzero (true) if they match.
        */
        bool b(!png_sig_cmp(buf, 0, PNG_BYTES_TO_CHECK));
        fclose(fp);
        return b;
}