Decrypt PDF(remove pdf password and limitations) with pdfium

pdfdecrypt.cpp

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

#include "../fpdfsdk/include/fpdfview.h"
#include "../fpdfsdk/include/fpdfsave.h"

/*
author:Steven Lee
website:http://blog.rubypdf.com
email:rocsky(at)gmail(dot)com
*/

FILE * pFile;
int writeBlock(FPDF_FILEWRITE* pThis, const void* pData, unsigned long size)
{
	int result= fwrite(pData, 1,size, pFile);
	return result;
}

int main(int argc, char* argv[])
{
	char * pwd=NULL;
	if(argc==4)
	{
		pwd=argv[3];
	}
	else if(argc==3)
	{
		//do nothing
	}
	else
	{
		fprintf(stderr,"Usage:%s input.pdf outputpdf [password]\n");
		fprintf(stderr,"password is not required \nonly when PDF is encrypted with the owner password, \n");
		fprintf(stderr,"password can be the owner password or user passoword \n");
		return -1;
	}

	FPDF_InitLibrary(NULL);
	char * input=argv[1];//"d:\\PDFCreator_op.pdf"
	char * output=argv[2];

	FPDF_DOCUMENT doc=FPDF_LoadDocument(input,NULL);
	int _errno =fopen_s (&pFile,output, "wb");
	char buff[256];
	if(_errno!=0)
	{
		//printf("Error opening file: %s.\n", strerror(_errno));
		strerror_s(buff, 100, _errno);
		fprintf(stderr,"Error opening file: %s.\n", buff);
		return -1;
	}

	FPDF_FILEWRITE  pFileWrite;
	pFileWrite.version=1;
	pFileWrite.WriteBlock=writeBlock;

	FPDF_SaveAsCopy(doc,&pFileWrite,FPDF_REMOVE_SECURITY);

	_errno=fclose (pFile);
	if(_errno!=0)
	{
		strerror_s(buff, 100, _errno);
		fprintf(stderr,"Error closing file: %s.\n", buff);
		return -1;
	}
	FPDF_DestroyLibrary();
	return 0;
}