introduced streaming integrity digest updater

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

2 files changed, 39 insertions, 0 deletions

diff --git a/src/eyetil.cc b/src/eyetil.cc
index cd22eea..6ccc4ae 100644
--- a/src/eyetil.cc
+++ b/src/eyetil.cc
@@ -86,12 +86,40 @@ binary_t md5_digester::final() {
 uint16_t block512_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 0xffff&~sum;
 }
 
+void integrity_digester::update(const void *d_,size_t s) {
+    uint8_t *d=(uint8_t*)d_;
+    if(data_size) {
+        int l = sizeof(data)-data_size;
+        if(l>s) {
+            memmove(data.dptr(data_size),d,s); data_size+=s; return;
+        }
+        memmove(data.dptr(data_size),d,l); d+=l; s-=l;
+        md5.update<uint16_t>( data.tcpcksum(data) );
+    }
+    if(s<sizeof(data)) {
+        memmove(data.dptr(0),d,s); data_size=s; return;
+    }
+    size_t bb=s/sizeof(block512_t);
+    std::transform((block512_t*)d,((block512_t*)d)+bb,
+            md5.updater<uint16_t>(),block512_t::tcpcksum);
+    size_t ss=bb*sizeof(block512_t);
+    d+=ss; s-=ss;
+    assert(s<sizeof(block512_t));
+    if(s) memmove(data.dptr(0),d,data_size=s);
+}
+
+binary_t integrity_digester::final(const std::string& ukey) {
+    assert(!data_size);
+    md5.update( binary_t(ukey) );
+    return md5.final();
+}
+
 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)) {
diff --git a/src/eyetil.h b/src/eyetil.h
index 7517ba6..8784cb4 100644
--- a/src/eyetil.h
+++ b/src/eyetil.h
@@ -71,12 +71,23 @@ struct block512_t {
     inline uint8_t *dptr(size_t o) { return ((uint8_t*)this)+o; }
 
     static uint16_t tcpcksum(block512_t& data);
 };
 #pragma pack()
 
+struct integrity_digester {
+    md5_digester md5;
+    size_t data_size;
+    block512_t data;
+
+    integrity_digester() : data_size(0) { }
+    void update(const void *d,size_t s);
+    binary_t final(const std::string& ukey);
+};
+
+
 class tmpdir_t {
     public:
         std::string dir;
 
         tmpdir_t(const std::string& dt);
         ~tmpdir_t();