(:description II► Apache Portable Runtime, utilisation d'un memory mapped file pour un calcul de hashage MD5:)

(:description II► Arnaud Grandville Consulting, Lille, conseils et intégration de solutions informatiques, memory mapped file pour un calcul de hashage MD5:)

(:keywords memory mapped file, apr, apache portable runtime, mmap, md5:) (:description »»» Arnaud Grandville Consulting, Lille, conseils et intégration de solutions informatiques, memory mapped file pour un calcul de hashage MD5:)

un exemple mise en oeuvre d'un memory mapped file pour un calcul de hashage MD5 sur de gros fichiers.

(:source lang=C :)

1. include "apr_mmap.h"
2. include "apr_strings.h"
3. include "apr_file_io.h"
4. include "apr_md5.h"

int main(int argc, char* argv[]) {

	apr_md5_ctx_t md5_ctx;
	apr_md5_init(&md5_ctx);
	unsigned char digest[APR_MD5_DIGESTSIZE];
	static apr_mmap_t *themmap = NULL;
	static apr_file_t *thefile = NULL;
	static apr_finfo_t finfo;

	apr_status_t rv;

	apr_pool_t *p;
	apr_initialize();
	apr_pool_create(&p, NULL);

	static char file1[]="c:\\Arte - 27-12-2006 13h58 1h20m.mpg";
	rv = apr_file_open(&thefile, file1, APR_READ, APR_UREAD | APR_GREAD, p);
	apr_file_info_get(&finfo, APR_FINFO_SIZE, thefile);

	apr_off_t offset=0;
	apr_size_t RemainingSize=(apr_size_t)finfo.size;
	apr_size_t ReadedSize=0;


	while(RemainingSize>0){

		offset+=ReadedSize;

		if(RemainingSize>APR_MMAP_LIMIT){
			ReadedSize = APR_MMAP_LIMIT;
		}
		else{
			ReadedSize = RemainingSize;
		}

		rv = apr_mmap_create(&themmap, thefile, offset, ReadedSize, APR_MMAP_READ, p);

		apr_md5_update(&md5_ctx,(char*)themmap->mm,ReadedSize);

		rv = apr_mmap_delete(themmap);
		RemainingSize-=ReadedSize;
	};

	apr_md5_final(digest,&md5_ctx);



	apr_file_close(thefile);
	apr_pool_destroy(p);
	for (int di = 0; di < 16; ++di)
	    printf("%02x", digest[di]);

	return 0;

}

(:sourcend:)