optimize integrity digest calculation memory use

Signed-off-by: Michael Krelin <hacker@klever.net>

1 files changed, 5 insertions, 9 deletions

diff --git a/src/eyetil.cc b/src/eyetil.cc
index 57ae607..2e6ab7e 100644
--- a/src/eyetil.cc
+++ b/src/eyetil.cc
@@ -1,177 +1,173 @@
 #include <stdlib.h>
 #include <sys/stat.h>
 #include <syslog.h>
 #include <iostream>
 #include <cassert>
 #include <stdexcept>
 #include <algorithm>
 #include <numeric>
 #include <openssl/md5.h>
 #include "eyetil.h"
 
 #include "config.h"
 #ifdef HAVE_LIBUUID
 # include <uuid/uuid.h>
 #endif
 
 binary_t& binary_t::from_hex(const std::string& h) {
     std::string::size_type hs = h.length();
     if(hs&1)
         throw std::runtime_error("odd number of characters in hexadecimal number");
     int rvs = hs>>1;
     resize(rvs);
     const unsigned char *hp = (const unsigned char*)h.data();
     iterator oi=begin();
     char t[3] = { 0,0,0 };
     for(int i=0;i<rvs;++i) {
         t[0]=*(hp++); t[1]=*(hp++);
         *(oi++) = strtol(t,0,16);
     }
     return *this;
 }
 
 binary_t& binary_t::from_data(const void *d,size_t s) {
     resize(s);
     std::copy((const unsigned char*)d,(const unsigned char *)d+s,
             begin() );
     return *this;
 }
 
 binary_t& binary_t::make_nonce() {
 #ifdef HAVE_LIBUUID
     uuid_t uuid;
     uuid_generate(uuid);
     from_data((unsigned char*)uuid,sizeof(uuid));
 #else
     resize(16);
     std::generate_n(begin(),16,rand);
 #endif /* HAVE_LIBUUID */
     return *this;
 }
 
 std::string binary_t::hex() const {
     std::string rv;
     rv.reserve((size()<<1)+1);
     char t[3] = {0,0,0};
     for(const_iterator i=begin(),ie=end();i!=ie;++i) {
         int rc = snprintf(t,sizeof(t),"%02x",*i);
         assert(rc<sizeof(t));
         rv += t;
     }
     return rv;
 }
 
 binary_t binary_t::md5() const {
     binary_t rv(MD5_DIGEST_LENGTH);
     if(!MD5(
                 (const unsigned char*)&(front()),size(),
                 (unsigned char*)&(rv.front()) ))
         throw std::runtime_error("failed to md5()");
     return rv;
 }
 
 void md5_digester::init() {
     if(!MD5_Init(&ctx)) throw std::runtime_error("failed to MD5_Init()");
 }
 void md5_digester::update(const void *d,size_t l) {
     if(!MD5_Update(&ctx,d,l)) throw std::runtime_error("failed to MD5_Update()");
 }
 binary_t md5_digester::final() {
     binary_t rv(MD5_DIGEST_LENGTH);
     if(!MD5_Final((unsigned char*)&(rv.front()), &ctx))
         throw std::runtime_error("failed to MD5_Final()");
     return rv;
 }
 
 
 static void make_path_for_template(const std::string& p,mode_t m) {
     struct stat st;
     std::string pp;
     for(std::string::size_type sl=p.find('/',1);
             sl!=std::string::npos;
             sl=p.find('/',sl+1)) {
         if(stat( (pp=p.substr(0,sl)).c_str() ,&st)
                 || !S_ISDIR(st.st_mode)) {
             if(mkdir(pp.c_str(),m))
                 throw std::runtime_error("failed to mkdir()");
         }
     }
 }
 
 tmpdir_t::tmpdir_t(const std::string& dt) : dir(dt) {
     make_path_for_template(dt,0777);
     if(!mkdtemp((char*)dir.data()))
         throw std::runtime_error("failed to mkdtmp()");
 }
 tmpdir_t::~tmpdir_t() {
     assert(!dir.empty());
     if(rmdir(dir.c_str())) {
         syslog(LOG_WARNING,"Failed to remove '%s' directory",dir.c_str());
     }
 }
 
 std::string tmpdir_t::get_file(const std::string& f) {
     std::string::size_type ls = f.rfind('/');
     return dir+'/'+(
             (ls==std::string::npos)
             ? f
             : f.substr(ls+1)
         );
 }
 
 tarchive_t::tarchive_t(void *p,size_t s) : a(archive_read_new()), e(0) {
     if(!a) throw std::runtime_error("failed to archive_read_new()");
     if(archive_read_support_format_tar(a)) {
         archive_read_finish(a);
         throw std::runtime_error("failed to archive_read_support_format_tar()");
     }
     if(archive_read_open_memory(a,p,s)) {
         archive_read_finish(a);
         throw std::runtime_error("failed to archive_read_open_memory()");
     }
 }
 tarchive_t::~tarchive_t() {
     assert(a);
     archive_read_finish(a);
 }
 
 bool tarchive_t::read_next_header() {
     assert(a);
     return archive_read_next_header(a,&e)==ARCHIVE_OK;
 }
 
 std::string tarchive_t::entry_pathname() {
     assert(a); assert(e);
     return archive_entry_pathname(e);
 }
 
 bool tarchive_t::read_data_into_fd(int fd) {
     assert(a);
     return archive_read_data_into_fd(a,fd)==ARCHIVE_OK;
 }
 
 #pragma pack(1)
 struct block512_t {
     enum { words = 512 / sizeof(uint16_t) };
     uint16_t data[words];
 
     static uint16_t tcpcksum(block512_t& data) {
         uint32_t sum = std::accumulate(data.data,data.data+words,0);
         while(uint32_t hw = sum>>16) sum = (sum&0xffff)+hw;
         return ~sum;
     }
 
 };
 #pragma pack()
 
 binary_t integrity_digest(const void *ptr,size_t size,const std::string& ukey) {
-    binary_t key; key.from_hex(ukey);
-    std::vector<uint16_t> blksums; blksums.reserve(size/sizeof(block512_t));
-    block512_t *db = (block512_t*)ptr,
-               *de = db + size/sizeof(block512_t);
-    std::transform( db, de, std::back_inserter(blksums), block512_t::tcpcksum );
-    binary_t subject;
-    subject.from_data((void*)&(blksums.front()),blksums.size()*sizeof(uint16_t));
-    std::copy( key.begin(), key.end(), std::back_inserter(subject) );
-    return subject.md5();
+    md5_digester rv;
+    std::transform( (block512_t*)ptr, ((block512_t*)ptr)+size/sizeof(block512_t),
+            rv.updater<uint16_t>(), block512_t::tcpcksum );
+    rv.update( binary_t(ukey) );
+    return rv.final();
 }