merged with apt--mvo

13 files changed, 592 insertions, 84 deletions

diff --git a/apt-pkg/contrib/configuration.cc b/apt-pkg/contrib/configuration.cc
index 09e454be9..14a000fa5 100644
--- a/apt-pkg/contrib/configuration.cc
+++ b/apt-pkg/contrib/configuration.cc
@@ -110,7 +110,7 @@ Configuration::Item *Configuration::Lookup(Item *Head,const char *S,
       return 0;
    
    I = new Item;
-   I->Tag = string(S,Len);
+   I->Tag.assign(S,Len);
    I->Next = *Last;
    I->Parent = Head;
    *Last = I;
@@ -161,7 +161,7 @@ string Configuration::Find(const char *Name,const char *Default) const
    if (Itm == 0 || Itm->Value.empty() == true)
    {
       if (Default == 0)
-	 return string();
+	 return "";
       else
 	 return Default;
    }
@@ -180,7 +180,7 @@ string Configuration::FindFile(const char *Name,const char *Default) const
    if (Itm == 0 || Itm->Value.empty() == true)
    {
       if (Default == 0)
-	 return string();
+	 return "";
       else
 	 return Default;
    }
@@ -294,7 +294,7 @@ string Configuration::FindAny(const char *Name,const char *Default) const
 // Configuration::CndSet - Conditinal Set a value			/*{{{*/
 // ---------------------------------------------------------------------
 /* This will not overwrite */
-void Configuration::CndSet(const char *Name,string Value)
+void Configuration::CndSet(const char *Name,const string &Value)
 {
    Item *Itm = Lookup(Name,true);
    if (Itm == 0)
@@ -306,7 +306,7 @@ void Configuration::CndSet(const char *Name,string Value)
 // Configuration::Set - Set a value					/*{{{*/
 // ---------------------------------------------------------------------
 /* */
-void Configuration::Set(const char *Name,string Value)
+void Configuration::Set(const char *Name,const string &Value)
 {
    Item *Itm = Lookup(Name,true);
    if (Itm == 0)
@@ -330,7 +330,7 @@ void Configuration::Set(const char *Name,int Value)
 // Configuration::Clear - Clear an single value from a list	        /*{{{*/
 // ---------------------------------------------------------------------
 /* */
-void Configuration::Clear(string Name, int Value)
+void Configuration::Clear(const string Name, int Value)
 {
    char S[300];
    snprintf(S,sizeof(S),"%i",Value);
@@ -340,7 +340,7 @@ void Configuration::Clear(string Name, int Value)
 // Configuration::Clear - Clear an single value from a list	        /*{{{*/
 // ---------------------------------------------------------------------
 /* */
-void Configuration::Clear(string Name, string Value)
+void Configuration::Clear(const string Name, string Value)
 {
    Item *Top = Lookup(Name.c_str(),false);
    if (Top == 0 || Top->Child == 0)
@@ -377,7 +377,7 @@ void Configuration::Clear(string Name)
    if (Top == 0) 
       return;
 
-   Top->Value = string();
+   Top->Value.clear();
    Item *Stop = Top;
    Top = Top->Child;
    Stop->Child = 0;
@@ -485,7 +485,7 @@ string Configuration::Item::FullTag(const Item *Stop) const
    sections like 'zone "foo.org" { .. };' This causes each section to be
    added in with a tag like "zone::foo.org" instead of being split 
    tag/value. AsSectional enables Sectional parsing.*/
-bool ReadConfigFile(Configuration &Conf,string FName,bool AsSectional,
+bool ReadConfigFile(Configuration &Conf,const string &FName,bool AsSectional,
 		    unsigned Depth)
 {   
    // Open the stream for reading
@@ -711,13 +711,13 @@ bool ReadConfigFile(Configuration &Conf,string FName,bool AsSectional,
 	    }
 	    
 	    // Empty the buffer
-	    LineBuffer = string();
+	    LineBuffer.clear();
 	    
 	    // Move up a tag, but only if there is no bit to parse
 	    if (TermChar == '}')
 	    {
 	       if (StackPos == 0)
-		  ParentTag = string();
+		  ParentTag.clear();
 	       else
 		  ParentTag = Stack[--StackPos];
 	    }
@@ -742,8 +742,8 @@ bool ReadConfigFile(Configuration &Conf,string FName,bool AsSectional,
 // ReadConfigDir - Read a directory of config files			/*{{{*/
 // ---------------------------------------------------------------------
 /* */
-bool ReadConfigDir(Configuration &Conf,string Dir,bool AsSectional,
-		    unsigned Depth)
+bool ReadConfigDir(Configuration &Conf,const string &Dir,bool AsSectional,
+		   unsigned Depth)
 {   
    DIR *D = opendir(Dir.c_str());
    if (D == 0)
diff --git a/apt-pkg/contrib/configuration.h b/apt-pkg/contrib/configuration.h
index 789bc82cf..0d4078dab 100644
--- a/apt-pkg/contrib/configuration.h
+++ b/apt-pkg/contrib/configuration.h
@@ -69,30 +69,30 @@ class Configuration
    public:
 
    string Find(const char *Name,const char *Default = 0) const;
-   string Find(string Name,const char *Default = 0) const {return Find(Name.c_str(),Default);};
+   string Find(const string Name,const char *Default = 0) const {return Find(Name.c_str(),Default);};
    string FindFile(const char *Name,const char *Default = 0) const;
    string FindDir(const char *Name,const char *Default = 0) const;
    int FindI(const char *Name,int Default = 0) const;
-   int FindI(string Name,int Default = 0) const {return FindI(Name.c_str(),Default);};
+   int FindI(const string Name,int Default = 0) const {return FindI(Name.c_str(),Default);};
    bool FindB(const char *Name,bool Default = false) const;
-   bool FindB(string Name,bool Default = false) const {return FindB(Name.c_str(),Default);};
+   bool FindB(const string Name,bool Default = false) const {return FindB(Name.c_str(),Default);};
    string FindAny(const char *Name,const char *Default = 0) const;
 	      
-   inline void Set(string Name,string Value) {Set(Name.c_str(),Value);};
-   void CndSet(const char *Name,string Value);
-   void Set(const char *Name,string Value);
+   inline void Set(const string Name,string Value) {Set(Name.c_str(),Value);};
+   void CndSet(const char *Name,const string &Value);
+   void Set(const char *Name,const string &Value);
    void Set(const char *Name,int Value);   
    
-   inline bool Exists(string Name) const {return Exists(Name.c_str());};
+   inline bool Exists(const string Name) const {return Exists(Name.c_str());};
    bool Exists(const char *Name) const;
    bool ExistsAny(const char *Name) const;
 
    // clear a whole tree
-   void Clear(string Name);
+   void Clear(const string Name);
 
    // remove a certain value from a list (e.g. the list of "APT::Keep-Fds")
-   void Clear(string List, string Value);
-   void Clear(string List, int Value);
+   void Clear(const string List, string Value);
+   void Clear(const string List, int Value);
 
    inline const Item *Tree(const char *Name) const {return Lookup(Name);};
 
@@ -106,10 +106,12 @@ class Configuration
 
 extern Configuration *_config;
 
-bool ReadConfigFile(Configuration &Conf,string FName,bool AsSectional = false,
+bool ReadConfigFile(Configuration &Conf,const string &FName,
+		    bool AsSectional = false,
 		    unsigned Depth = 0);
 
-bool ReadConfigDir(Configuration &Conf,string Dir,bool AsSectional = false,
-		    unsigned Depth = 0);
+bool ReadConfigDir(Configuration &Conf,const string &Dir,
+		   bool AsSectional = false,
+		   unsigned Depth = 0);
 
 #endif
diff --git a/apt-pkg/contrib/hashes.cc b/apt-pkg/contrib/hashes.cc
index b17b94319..9b22a90d3 100644
--- a/apt-pkg/contrib/hashes.cc
+++ b/apt-pkg/contrib/hashes.cc
@@ -36,6 +36,7 @@ bool Hashes::AddFD(int Fd,unsigned long Size)
       Size -= Res;
       MD5.Add(Buf,Res);
       SHA1.Add(Buf,Res);
+      SHA256.Add(Buf,Res);
    }
    return true;
 }
diff --git a/apt-pkg/contrib/hashes.h b/apt-pkg/contrib/hashes.h
index 40bbe00a0..eefa7bf41 100644
--- a/apt-pkg/contrib/hashes.h
+++ b/apt-pkg/contrib/hashes.h
@@ -19,6 +19,7 @@
 
 #include <apt-pkg/md5.h>
 #include <apt-pkg/sha1.h>
+#include <apt-pkg/sha256.h>
 
 #include <algorithm>
 
@@ -30,10 +31,11 @@ class Hashes
 
    MD5Summation MD5;
    SHA1Summation SHA1;
+   SHA256Summation SHA256;
    
    inline bool Add(const unsigned char *Data,unsigned long Size)
    {
-      return MD5.Add(Data,Size) && SHA1.Add(Data,Size);
+      return MD5.Add(Data,Size) && SHA1.Add(Data,Size) && SHA256.Add(Data,Size);
    };
    inline bool Add(const char *Data) {return Add((unsigned char *)Data,strlen(Data));};
    bool AddFD(int Fd,unsigned long Size);
diff --git a/apt-pkg/contrib/md5.h b/apt-pkg/contrib/md5.h
index 9e20f7cef..e280d714e 100644
--- a/apt-pkg/contrib/md5.h
+++ b/apt-pkg/contrib/md5.h
@@ -29,6 +29,7 @@
 
 #include <string>
 #include <algorithm>
+#include <stdint.h>
 
 using std::string;
 using std::min;
@@ -58,7 +59,7 @@ class MD5SumValue
 
 class MD5Summation
 {
-   unsigned char Buf[4*4];
+   uint32_t Buf[4];
    unsigned char Bytes[2*4];
    unsigned char In[16*4];
    bool Done;
diff --git a/apt-pkg/contrib/mmap.cc b/apt-pkg/contrib/mmap.cc
index bc22fba67..e395e6cc7 100644
--- a/apt-pkg/contrib/mmap.cc
+++ b/apt-pkg/contrib/mmap.cc
@@ -155,9 +155,9 @@ DynamicMMap::DynamicMMap(FileFd &F,unsigned long Flags,unsigned long WorkSpace)
    unsigned long EndOfFile = Fd->Size();
    if (EndOfFile > WorkSpace)
       WorkSpace = EndOfFile;
-   else
+   else if(WorkSpace > 0)
    {
-      Fd->Seek(WorkSpace);
+      Fd->Seek(WorkSpace - 1);
       char C = 0;
       Fd->Write(&C,sizeof(C));
    }
diff --git a/apt-pkg/contrib/mmap.h b/apt-pkg/contrib/mmap.h
index caffa0f90..e329b167a 100644
--- a/apt-pkg/contrib/mmap.h
+++ b/apt-pkg/contrib/mmap.h
@@ -94,7 +94,7 @@ class DynamicMMap : public MMap
    unsigned long RawAllocate(unsigned long Size,unsigned long Aln = 0);
    unsigned long Allocate(unsigned long ItemSize);
    unsigned long WriteString(const char *String,unsigned long Len = (unsigned long)-1);
-   inline unsigned long WriteString(string S) {return WriteString(S.c_str(),S.length());};
+   inline unsigned long WriteString(const string &S) {return WriteString(S.c_str(),S.length());};
    void UsePools(Pool &P,unsigned int Count) {Pools = &P; PoolCount = Count;};
    
    DynamicMMap(FileFd &F,unsigned long Flags,unsigned long WorkSpace = 2*1024*1024);
diff --git a/apt-pkg/contrib/progress.cc b/apt-pkg/contrib/progress.cc
index 8eb36fc20..e3db9a45a 100644
--- a/apt-pkg/contrib/progress.cc
+++ b/apt-pkg/contrib/progress.cc
@@ -50,7 +50,7 @@ void OpProgress::Progress(unsigned long Cur)
 // ---------------------------------------------------------------------
 /* */
 void OpProgress::OverallProgress(unsigned long Current, unsigned long Total,
-	  			 unsigned long Size,string Op)
+	  			 unsigned long Size,const string &Op)
 {
    this->Current = Current;
    this->Total = Total;
@@ -67,7 +67,7 @@ void OpProgress::OverallProgress(unsigned long Current, unsigned long Total,
 // OpProgress::SubProgress - Set the sub progress state			/*{{{*/
 // ---------------------------------------------------------------------
 /* */
-void OpProgress::SubProgress(unsigned long SubTotal,string Op)
+void OpProgress::SubProgress(unsigned long SubTotal,const string &Op)
 {
    this->SubTotal = SubTotal;
    SubOp = Op;
@@ -115,6 +115,8 @@ bool OpProgress::CheckChange(float Interval)
    
    if ((int)LastPercent == (int)Percent)
       return false;
+
+   LastPercent = Percent;
    
    if (Interval == 0)
       return false;
@@ -126,7 +128,6 @@ bool OpProgress::CheckChange(float Interval)
    if (Diff < Interval)
       return false;
    LastTime = Now;   
-   LastPercent = Percent;
    return true;
 }
 									/*}}}*/
diff --git a/apt-pkg/contrib/progress.h b/apt-pkg/contrib/progress.h
index d0b1f5f94..20caf4cdf 100644
--- a/apt-pkg/contrib/progress.h
+++ b/apt-pkg/contrib/progress.h
@@ -59,9 +59,9 @@ class OpProgress
    
    void Progress(unsigned long Current);
    void SubProgress(unsigned long SubTotal);
-   void SubProgress(unsigned long SubTotal,string Op);
+   void SubProgress(unsigned long SubTotal,const string &Op);
    void OverallProgress(unsigned long Current,unsigned long Total,
-			unsigned long Size,string Op);
+			unsigned long Size,const string &Op);
    virtual void Done() {};
    
    OpProgress();
diff --git a/apt-pkg/contrib/sha256.cc b/apt-pkg/contrib/sha256.cc
new file mode 100644
index 000000000..ecda3d8e8
--- /dev/null
+++ b/apt-pkg/contrib/sha256.cc
@@ -0,0 +1,430 @@
+/*
+ * Cryptographic API.
+ *
+ * SHA-256, as specified in
+ * http://csrc.nist.gov/cryptval/shs/sha256-384-512.pdf
+ *
+ * SHA-256 code by Jean-Luc Cooke <jlcooke@certainkey.com>.
+ *
+ * Copyright (c) Jean-Luc Cooke <jlcooke@certainkey.com>
+ * Copyright (c) Andrew McDonald <andrew@mcdonald.org.uk>
+ * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
+ *
+ * Ported from the Linux kernel to Apt by Anthony Towns <ajt@debian.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option) 
+ * any later version.
+ *
+ */
+
+#ifdef __GNUG__
+#pragma implementation "apt-pkg/sha256.h"
+#endif
+
+
+#define SHA256_DIGEST_SIZE      32
+#define SHA256_HMAC_BLOCK_SIZE  64
+
+#define ror32(value,bits) (((value) >> (bits)) | ((value) << (32 - (bits))))
+
+#include <apt-pkg/sha256.h>
+#include <apt-pkg/strutl.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <arpa/inet.h>
+
+typedef uint32_t u32;
+typedef uint8_t  u8;
+
+static inline u32 Ch(u32 x, u32 y, u32 z)
+{
+        return z ^ (x & (y ^ z));
+}
+
+static inline u32 Maj(u32 x, u32 y, u32 z)
+{
+        return (x & y) | (z & (x | y));
+}
+
+#define e0(x)       (ror32(x, 2) ^ ror32(x,13) ^ ror32(x,22))
+#define e1(x)       (ror32(x, 6) ^ ror32(x,11) ^ ror32(x,25))
+#define s0(x)       (ror32(x, 7) ^ ror32(x,18) ^ (x >> 3))
+#define s1(x)       (ror32(x,17) ^ ror32(x,19) ^ (x >> 10))
+
+#define H0         0x6a09e667
+#define H1         0xbb67ae85
+#define H2         0x3c6ef372
+#define H3         0xa54ff53a
+#define H4         0x510e527f
+#define H5         0x9b05688c
+#define H6         0x1f83d9ab
+#define H7         0x5be0cd19
+
+static inline void LOAD_OP(int I, u32 *W, const u8 *input)
+{
+	W[I] = (  ((u32) input[I * 4 + 0] << 24)
+		| ((u32) input[I * 4 + 1] << 16)
+		| ((u32) input[I * 4 + 2] << 8)
+		| ((u32) input[I * 4 + 3]));
+}
+
+static inline void BLEND_OP(int I, u32 *W)
+{
+        W[I] = s1(W[I-2]) + W[I-7] + s0(W[I-15]) + W[I-16];
+}
+
+static void sha256_transform(u32 *state, const u8 *input)
+{
+        u32 a, b, c, d, e, f, g, h, t1, t2;
+        u32 W[64];
+        int i;
+
+        /* load the input */
+        for (i = 0; i < 16; i++)
+                LOAD_OP(i, W, input);
+
+        /* now blend */
+        for (i = 16; i < 64; i++)
+                BLEND_OP(i, W);
+    
+        /* load the state into our registers */
+        a=state[0];  b=state[1];  c=state[2];  d=state[3];
+        e=state[4];  f=state[5];  g=state[6];  h=state[7];
+
+        /* now iterate */
+        t1 = h + e1(e) + Ch(e,f,g) + 0x428a2f98 + W[ 0];
+        t2 = e0(a) + Maj(a,b,c);    d+=t1;    h=t1+t2;
+        t1 = g + e1(d) + Ch(d,e,f) + 0x71374491 + W[ 1];
+        t2 = e0(h) + Maj(h,a,b);    c+=t1;    g=t1+t2;
+        t1 = f + e1(c) + Ch(c,d,e) + 0xb5c0fbcf + W[ 2];
+        t2 = e0(g) + Maj(g,h,a);    b+=t1;    f=t1+t2;
+        t1 = e + e1(b) + Ch(b,c,d) + 0xe9b5dba5 + W[ 3];
+        t2 = e0(f) + Maj(f,g,h);    a+=t1;    e=t1+t2;
+        t1 = d + e1(a) + Ch(a,b,c) + 0x3956c25b + W[ 4];
+        t2 = e0(e) + Maj(e,f,g);    h+=t1;    d=t1+t2;
+        t1 = c + e1(h) + Ch(h,a,b) + 0x59f111f1 + W[ 5];
+        t2 = e0(d) + Maj(d,e,f);    g+=t1;    c=t1+t2;
+        t1 = b + e1(g) + Ch(g,h,a) + 0x923f82a4 + W[ 6];
+        t2 = e0(c) + Maj(c,d,e);    f+=t1;    b=t1+t2;
+        t1 = a + e1(f) + Ch(f,g,h) + 0xab1c5ed5 + W[ 7];
+        t2 = e0(b) + Maj(b,c,d);    e+=t1;    a=t1+t2;
+
+        t1 = h + e1(e) + Ch(e,f,g) + 0xd807aa98 + W[ 8];
+        t2 = e0(a) + Maj(a,b,c);    d+=t1;    h=t1+t2;
+        t1 = g + e1(d) + Ch(d,e,f) + 0x12835b01 + W[ 9];
+        t2 = e0(h) + Maj(h,a,b);    c+=t1;    g=t1+t2;
+        t1 = f + e1(c) + Ch(c,d,e) + 0x243185be + W[10];
+        t2 = e0(g) + Maj(g,h,a);    b+=t1;    f=t1+t2;
+        t1 = e + e1(b) + Ch(b,c,d) + 0x550c7dc3 + W[11];
+        t2 = e0(f) + Maj(f,g,h);    a+=t1;    e=t1+t2;
+        t1 = d + e1(a) + Ch(a,b,c) + 0x72be5d74 + W[12];
+        t2 = e0(e) + Maj(e,f,g);    h+=t1;    d=t1+t2;
+        t1 = c + e1(h) + Ch(h,a,b) + 0x80deb1fe + W[13];
+        t2 = e0(d) + Maj(d,e,f);    g+=t1;    c=t1+t2;
+        t1 = b + e1(g) + Ch(g,h,a) + 0x9bdc06a7 + W[14];
+        t2 = e0(c) + Maj(c,d,e);    f+=t1;    b=t1+t2;
+        t1 = a + e1(f) + Ch(f,g,h) + 0xc19bf174 + W[15];
+        t2 = e0(b) + Maj(b,c,d);    e+=t1;    a=t1+t2;
+
+        t1 = h + e1(e) + Ch(e,f,g) + 0xe49b69c1 + W[16];
+        t2 = e0(a) + Maj(a,b,c);    d+=t1;    h=t1+t2;
+        t1 = g + e1(d) + Ch(d,e,f) + 0xefbe4786 + W[17];
+        t2 = e0(h) + Maj(h,a,b);    c+=t1;    g=t1+t2;
+        t1 = f + e1(c) + Ch(c,d,e) + 0x0fc19dc6 + W[18];
+        t2 = e0(g) + Maj(g,h,a);    b+=t1;    f=t1+t2;
+        t1 = e + e1(b) + Ch(b,c,d) + 0x240ca1cc + W[19];
+        t2 = e0(f) + Maj(f,g,h);    a+=t1;    e=t1+t2;
+        t1 = d + e1(a) + Ch(a,b,c) + 0x2de92c6f + W[20];
+        t2 = e0(e) + Maj(e,f,g);    h+=t1;    d=t1+t2;
+        t1 = c + e1(h) + Ch(h,a,b) + 0x4a7484aa + W[21];
+        t2 = e0(d) + Maj(d,e,f);    g+=t1;    c=t1+t2;
+        t1 = b + e1(g) + Ch(g,h,a) + 0x5cb0a9dc + W[22];
+        t2 = e0(c) + Maj(c,d,e);    f+=t1;    b=t1+t2;
+        t1 = a + e1(f) + Ch(f,g,h) + 0x76f988da + W[23];
+        t2 = e0(b) + Maj(b,c,d);    e+=t1;    a=t1+t2;
+
+        t1 = h + e1(e) + Ch(e,f,g) + 0x983e5152 + W[24];
+        t2 = e0(a) + Maj(a,b,c);    d+=t1;    h=t1+t2;
+        t1 = g + e1(d) + Ch(d,e,f) + 0xa831c66d + W[25];
+        t2 = e0(h) + Maj(h,a,b);    c+=t1;    g=t1+t2;
+        t1 = f + e1(c) + Ch(c,d,e) + 0xb00327c8 + W[26];
+        t2 = e0(g) + Maj(g,h,a);    b+=t1;    f=t1+t2;
+        t1 = e + e1(b) + Ch(b,c,d) + 0xbf597fc7 + W[27];
+        t2 = e0(f) + Maj(f,g,h);    a+=t1;    e=t1+t2;
+        t1 = d + e1(a) + Ch(a,b,c) + 0xc6e00bf3 + W[28];
+        t2 = e0(e) + Maj(e,f,g);    h+=t1;    d=t1+t2;
+        t1 = c + e1(h) + Ch(h,a,b) + 0xd5a79147 + W[29];
+        t2 = e0(d) + Maj(d,e,f);    g+=t1;    c=t1+t2;
+        t1 = b + e1(g) + Ch(g,h,a) + 0x06ca6351 + W[30];
+        t2 = e0(c) + Maj(c,d,e);    f+=t1;    b=t1+t2;
+        t1 = a + e1(f) + Ch(f,g,h) + 0x14292967 + W[31];
+        t2 = e0(b) + Maj(b,c,d);    e+=t1;    a=t1+t2;
+
+        t1 = h + e1(e) + Ch(e,f,g) + 0x27b70a85 + W[32];
+        t2 = e0(a) + Maj(a,b,c);    d+=t1;    h=t1+t2;
+        t1 = g + e1(d) + Ch(d,e,f) + 0x2e1b2138 + W[33];
+        t2 = e0(h) + Maj(h,a,b);    c+=t1;    g=t1+t2;
+        t1 = f + e1(c) + Ch(c,d,e) + 0x4d2c6dfc + W[34];
+        t2 = e0(g) + Maj(g,h,a);    b+=t1;    f=t1+t2;
+        t1 = e + e1(b) + Ch(b,c,d) + 0x53380d13 + W[35];
+        t2 = e0(f) + Maj(f,g,h);    a+=t1;    e=t1+t2;
+        t1 = d + e1(a) + Ch(a,b,c) + 0x650a7354 + W[36];
+        t2 = e0(e) + Maj(e,f,g);    h+=t1;    d=t1+t2;
+        t1 = c + e1(h) + Ch(h,a,b) + 0x766a0abb + W[37];
+        t2 = e0(d) + Maj(d,e,f);    g+=t1;    c=t1+t2;
+        t1 = b + e1(g) + Ch(g,h,a) + 0x81c2c92e + W[38];
+        t2 = e0(c) + Maj(c,d,e);    f+=t1;    b=t1+t2;
+        t1 = a + e1(f) + Ch(f,g,h) + 0x92722c85 + W[39];
+        t2 = e0(b) + Maj(b,c,d);    e+=t1;    a=t1+t2;
+
+        t1 = h + e1(e) + Ch(e,f,g) + 0xa2bfe8a1 + W[40];
+        t2 = e0(a) + Maj(a,b,c);    d+=t1;    h=t1+t2;
+        t1 = g + e1(d) + Ch(d,e,f) + 0xa81a664b + W[41];
+        t2 = e0(h) + Maj(h,a,b);    c+=t1;    g=t1+t2;
+        t1 = f + e1(c) + Ch(c,d,e) + 0xc24b8b70 + W[42];
+        t2 = e0(g) + Maj(g,h,a);    b+=t1;    f=t1+t2;
+        t1 = e + e1(b) + Ch(b,c,d) + 0xc76c51a3 + W[43];
+        t2 = e0(f) + Maj(f,g,h);    a+=t1;    e=t1+t2;
+        t1 = d + e1(a) + Ch(a,b,c) + 0xd192e819 + W[44];
+        t2 = e0(e) + Maj(e,f,g);    h+=t1;    d=t1+t2;
+        t1 = c + e1(h) + Ch(h,a,b) + 0xd6990624 + W[45];
+        t2 = e0(d) + Maj(d,e,f);    g+=t1;    c=t1+t2;
+        t1 = b + e1(g) + Ch(g,h,a) + 0xf40e3585 + W[46];
+        t2 = e0(c) + Maj(c,d,e);    f+=t1;    b=t1+t2;
+        t1 = a + e1(f) + Ch(f,g,h) + 0x106aa070 + W[47];
+        t2 = e0(b) + Maj(b,c,d);    e+=t1;    a=t1+t2;
+
+        t1 = h + e1(e) + Ch(e,f,g) + 0x19a4c116 + W[48];
+        t2 = e0(a) + Maj(a,b,c);    d+=t1;    h=t1+t2;
+        t1 = g + e1(d) + Ch(d,e,f) + 0x1e376c08 + W[49];
+        t2 = e0(h) + Maj(h,a,b);    c+=t1;    g=t1+t2;
+        t1 = f + e1(c) + Ch(c,d,e) + 0x2748774c + W[50];
+        t2 = e0(g) + Maj(g,h,a);    b+=t1;    f=t1+t2;
+        t1 = e + e1(b) + Ch(b,c,d) + 0x34b0bcb5 + W[51];
+        t2 = e0(f) + Maj(f,g,h);    a+=t1;    e=t1+t2;
+        t1 = d + e1(a) + Ch(a,b,c) + 0x391c0cb3 + W[52];
+        t2 = e0(e) + Maj(e,f,g);    h+=t1;    d=t1+t2;
+        t1 = c + e1(h) + Ch(h,a,b) + 0x4ed8aa4a + W[53];
+        t2 = e0(d) + Maj(d,e,f);    g+=t1;    c=t1+t2;
+        t1 = b + e1(g) + Ch(g,h,a) + 0x5b9cca4f + W[54];
+        t2 = e0(c) + Maj(c,d,e);    f+=t1;    b=t1+t2;
+        t1 = a + e1(f) + Ch(f,g,h) + 0x682e6ff3 + W[55];
+        t2 = e0(b) + Maj(b,c,d);    e+=t1;    a=t1+t2;
+
+        t1 = h + e1(e) + Ch(e,f,g) + 0x748f82ee + W[56];
+        t2 = e0(a) + Maj(a,b,c);    d+=t1;    h=t1+t2;
+        t1 = g + e1(d) + Ch(d,e,f) + 0x78a5636f + W[57];
+        t2 = e0(h) + Maj(h,a,b);    c+=t1;    g=t1+t2;
+        t1 = f + e1(c) + Ch(c,d,e) + 0x84c87814 + W[58];
+        t2 = e0(g) + Maj(g,h,a);    b+=t1;    f=t1+t2;
+        t1 = e + e1(b) + Ch(b,c,d) + 0x8cc70208 + W[59];
+        t2 = e0(f) + Maj(f,g,h);    a+=t1;    e=t1+t2;
+        t1 = d + e1(a) + Ch(a,b,c) + 0x90befffa + W[60];
+        t2 = e0(e) + Maj(e,f,g);    h+=t1;    d=t1+t2;
+        t1 = c + e1(h) + Ch(h,a,b) + 0xa4506ceb + W[61];
+        t2 = e0(d) + Maj(d,e,f);    g+=t1;    c=t1+t2;
+        t1 = b + e1(g) + Ch(g,h,a) + 0xbef9a3f7 + W[62];
+        t2 = e0(c) + Maj(c,d,e);    f+=t1;    b=t1+t2;
+        t1 = a + e1(f) + Ch(f,g,h) + 0xc67178f2 + W[63];
+        t2 = e0(b) + Maj(b,c,d);    e+=t1;    a=t1+t2;
+
+        state[0] += a; state[1] += b; state[2] += c; state[3] += d;
+        state[4] += e; state[5] += f; state[6] += g; state[7] += h;
+
+        /* clear any sensitive info... */
+        a = b = c = d = e = f = g = h = t1 = t2 = 0;
+        memset(W, 0, 64 * sizeof(u32));
+}
+
+SHA256Summation::SHA256Summation()
+{
+        Sum.state[0] = H0;
+        Sum.state[1] = H1;
+        Sum.state[2] = H2;
+        Sum.state[3] = H3;
+        Sum.state[4] = H4;
+        Sum.state[5] = H5;
+        Sum.state[6] = H6;
+        Sum.state[7] = H7;
+        Sum.count[0] = Sum.count[1] = 0;
+        memset(Sum.buf, 0, sizeof(Sum.buf));
+        Done = false;
+}
+
+bool SHA256Summation::Add(const u8 *data, unsigned long len)
+{
+        struct sha256_ctx *sctx = &Sum;
+        unsigned int i, index, part_len;
+
+        if (Done) return false;
+
+        /* Compute number of bytes mod 128 */
+        index = (unsigned int)((sctx->count[0] >> 3) & 0x3f);
+
+        /* Update number of bits */
+        if ((sctx->count[0] += (len << 3)) < (len << 3)) {
+                sctx->count[1]++;
+                sctx->count[1] += (len >> 29);
+        }
+
+        part_len = 64 - index;
+
+        /* Transform as many times as possible. */
+        if (len >= part_len) {
+                memcpy(&sctx->buf[index], data, part_len);
+                sha256_transform(sctx->state, sctx->buf);
+
+                for (i = part_len; i + 63 < len; i += 64)
+                        sha256_transform(sctx->state, &data[i]);
+                index = 0;
+        } else {
+                i = 0;
+        }
+
+        /* Buffer remaining input */
+        memcpy(&sctx->buf[index], &data[i], len-i);
+
+        return true;
+}
+
+SHA256SumValue SHA256Summation::Result()
+{
+   struct sha256_ctx *sctx = &Sum;
+   if (!Done) {
+        u8 bits[8];
+        unsigned int index, pad_len, t;
+        static const u8 padding[64] = { 0x80, };
+
+        /* Save number of bits */
+        t = sctx->count[0];
+        bits[7] = t; t >>= 8;
+        bits[6] = t; t >>= 8;
+        bits[5] = t; t >>= 8;
+        bits[4] = t;
+        t = sctx->count[1];
+        bits[3] = t; t >>= 8;
+        bits[2] = t; t >>= 8;
+        bits[1] = t; t >>= 8;
+        bits[0] = t;
+
+        /* Pad out to 56 mod 64. */
+        index = (sctx->count[0] >> 3) & 0x3f;
+        pad_len = (index < 56) ? (56 - index) : ((64+56) - index);
+        Add(padding, pad_len);
+
+        /* Append length (before padding) */
+        Add(bits, 8);
+   }
+
+   Done = true;
+
+   /* Store state in digest */
+
+   SHA256SumValue res;
+   u8 *out = res.Sum;
+
+   int i, j;
+   unsigned int t;
+   for (i = j = 0; i < 8; i++, j += 4) {
+      t = sctx->state[i];
+      out[j+3] = t; t >>= 8;
+      out[j+2] = t; t >>= 8;
+      out[j+1] = t; t >>= 8;
+      out[j  ] = t;
+   }
+
+   return res;
+}
+
+// SHA256SumValue::SHA256SumValue - Constructs the sum from a string   /*{{{*/
+// ---------------------------------------------------------------------
+/* The string form of a SHA256 is a 64 character hex number */
+SHA256SumValue::SHA256SumValue(string Str)
+{
+   memset(Sum,0,sizeof(Sum));
+   Set(Str);
+}
+
+                                                                       /*}}}*/
+// SHA256SumValue::SHA256SumValue - Default constructor                /*{{{*/
+// ---------------------------------------------------------------------
+/* Sets the value to 0 */
+SHA256SumValue::SHA256SumValue()
+{
+   memset(Sum,0,sizeof(Sum));
+}
+
+                                                                       /*}}}*/
+// SHA256SumValue::Set - Set the sum from a string                     /*{{{*/
+// ---------------------------------------------------------------------
+/* Converts the hex string into a set of chars */
+bool SHA256SumValue::Set(string Str)
+{
+   return Hex2Num(Str,Sum,sizeof(Sum));
+}
+                                                                       /*}}}*/
+// SHA256SumValue::Value - Convert the number into a string            /*{{{*/
+// ---------------------------------------------------------------------
+/* Converts the set of chars into a hex string in lower case */
+string SHA256SumValue::Value() const
+{
+   char Conv[16] =
+      { '0','1','2','3','4','5','6','7','8','9','a','b',
+      'c','d','e','f'
+   };
+   char Result[65];
+   Result[64] = 0;
+
+   // Convert each char into two letters
+   int J = 0;
+   int I = 0;
+   for (; I != 64; J++,I += 2)
+   {
+      Result[I] = Conv[Sum[J] >> 4];
+      Result[I + 1] = Conv[Sum[J] & 0xF];
+   }
+
+   return string(Result);
+}
+
+
+
+// SHA256SumValue::operator == - Comparator                            /*{{{*/
+// ---------------------------------------------------------------------
+/* Call memcmp on the buffer */
+bool SHA256SumValue::operator == (const SHA256SumValue & rhs) const
+{
+   return memcmp(Sum,rhs.Sum,sizeof(Sum)) == 0;
+}
+                                                                       /*}}}*/
+
+
+// SHA256Summation::AddFD - Add content of file into the checksum      /*{{{*/
+// ---------------------------------------------------------------------
+/* */
+bool SHA256Summation::AddFD(int Fd,unsigned long Size)
+{
+   unsigned char Buf[64 * 64];
+   int Res = 0;
+   int ToEOF = (Size == 0);
+   while (Size != 0 || ToEOF)
+   {
+      unsigned n = sizeof(Buf);
+      if (!ToEOF) n = min(Size,(unsigned long)n);
+      Res = read(Fd,Buf,n);
+      if (Res < 0 || (!ToEOF && (unsigned) Res != n)) // error, or short read
+         return false;
+      if (ToEOF && Res == 0) // EOF
+         break;
+      Size -= Res;
+      Add(Buf,Res);
+   }
+   return true;
+}
+                                                                       /*}}}*/
+
diff --git a/apt-pkg/contrib/sha256.h b/apt-pkg/contrib/sha256.h
new file mode 100644
index 000000000..70b3ae2ad
--- /dev/null
+++ b/apt-pkg/contrib/sha256.h
@@ -0,0 +1,74 @@
+// -*- mode: cpp; mode: fold -*-
+// Description                                                          /*{{{*/
+// $Id: sha1.h,v 1.3 2001/05/07 05:05:47 jgg Exp $
+/* ######################################################################
+
+   SHA256SumValue - Storage for a SHA-256 hash.
+   SHA256Summation - SHA-256 Secure Hash Algorithm.
+   
+   This is a C++ interface to a set of SHA256Sum functions, that mirrors
+   the equivalent MD5 & SHA1 classes. 
+
+   ##################################################################### */
+                                                                        /*}}}*/
+#ifndef APTPKG_SHA256_H
+#define APTPKG_SHA256_H
+
+#ifdef __GNUG__
+#pragma interface "apt-pkg/sha256.h"
+#endif 
+
+#include <string>
+#include <algorithm>
+
+using std::string;
+using std::min;
+
+class SHA256Summation;
+
+class SHA256SumValue
+{
+   friend class SHA256Summation;
+   unsigned char Sum[32];
+   
+   public:
+
+   // Accessors
+   bool operator ==(const SHA256SumValue &rhs) const; 
+   string Value() const;
+   inline void Value(unsigned char S[32])
+         {for (int I = 0; I != sizeof(Sum); I++) S[I] = Sum[I];};
+   inline operator string() const {return Value();};
+   bool Set(string Str);
+   inline void Set(unsigned char S[32]) 
+         {for (int I = 0; I != sizeof(Sum); I++) Sum[I] = S[I];};
+
+   SHA256SumValue(string Str);
+   SHA256SumValue();
+};
+
+struct sha256_ctx {
+    uint32_t count[2];
+    uint32_t state[8];
+    uint8_t buf[128];
+};
+
+class SHA256Summation
+{
+   struct sha256_ctx Sum;
+
+   bool Done;
+
+   public:
+
+   bool Add(const unsigned char *inbuf,unsigned long inlen);
+   inline bool Add(const char *Data) {return Add((unsigned char *)Data,strlen(Data));};
+   bool AddFD(int Fd,unsigned long Size);
+   inline bool Add(const unsigned char *Beg,const unsigned char *End) 
+                  {return Add(Beg,End-Beg);};
+   SHA256SumValue Result();
+   
+   SHA256Summation();
+};
+
+#endif
diff --git a/apt-pkg/contrib/strutl.cc b/apt-pkg/contrib/strutl.cc
index a75fbdf92..d96155917 100644
--- a/apt-pkg/contrib/strutl.cc
+++ b/apt-pkg/contrib/strutl.cc
@@ -199,10 +199,10 @@ bool ParseCWord(const char *&String,string &Res)
 // QuoteString - Convert a string into quoted from			/*{{{*/
 // ---------------------------------------------------------------------
 /* */
-string QuoteString(string Str,const char *Bad)
+string QuoteString(const string &Str, const char *Bad)
 {
    string Res;
-   for (string::iterator I = Str.begin(); I != Str.end(); I++)
+   for (string::const_iterator I = Str.begin(); I != Str.end(); I++)
    {
       if (strchr(Bad,*I) != 0 || isprint(*I) == 0 || 
 	  *I <= 0x20 || *I >= 0x7F)
@@ -220,7 +220,7 @@ string QuoteString(string Str,const char *Bad)
 // DeQuoteString - Convert a string from quoted from                    /*{{{*/
 // ---------------------------------------------------------------------
 /* This undoes QuoteString */
-string DeQuoteString(string Str)
+string DeQuoteString(const string &Str)
 {
    string Res;
    for (string::const_iterator I = Str.begin(); I != Str.end(); I++)
@@ -317,7 +317,7 @@ string TimeToStr(unsigned long Sec)
 // SubstVar - Substitute a string for another string			/*{{{*/
 // ---------------------------------------------------------------------
 /* This replaces all occurances of Subst with Contents in Str. */
-string SubstVar(string Str,string Subst,string Contents)
+string SubstVar(const string &Str,const string &Subst,const string &Contents)
 {
    string::size_type Pos = 0;
    string::size_type OldPos = 0;
@@ -348,21 +348,18 @@ string SubstVar(string Str,const struct SubstVar *Vars)
 /* This converts a URI into a safe filename. It quotes all unsafe characters
    and converts / to _ and removes the scheme identifier. The resulting
    file name should be unique and never occur again for a different file */
-string URItoFileName(string URI)
+string URItoFileName(const string &URI)
 {
    // Nuke 'sensitive' items
    ::URI U(URI);
-   U.User = string();
-   U.Password = string();
-   U.Access = "";
+   U.User.clear();
+   U.Password.clear();
+   U.Access.clear();
    
    // "\x00-\x20{}|\\\\^\\[\\]<>\"\x7F-\xFF";
-   URI = QuoteString(U,"\\|{}[]<>\"^~_=!@#$%^&*");
-   string::iterator J = URI.begin();
-   for (; J != URI.end(); J++)
-      if (*J == '/') 
-	 *J = '_';
-   return URI;
+   string NewURI = QuoteString(U,"\\|{}[]<>\"^~_=!@#$%^&*");
+   replace(NewURI.begin(),NewURI.end(),'/','_');
+   return NewURI;
 }
 									/*}}}*/
 // Base64Encode - Base64 Encoding routine for short strings		/*{{{*/
@@ -371,7 +368,7 @@ string URItoFileName(string URI)
    from wget and then patched and bug fixed.
  
    This spec can be found in rfc2045 */
-string Base64Encode(string S)
+string Base64Encode(const string &S)
 {
    // Conversion table.
    static char tbl[64] = {'A','B','C','D','E','F','G','H',
@@ -540,17 +537,17 @@ int stringcasecmp(string::const_iterator A,string::const_iterator AEnd,
 // ---------------------------------------------------------------------
 /* The format is like those used in package files and the method 
    communication system */
-string LookupTag(string Message,const char *Tag,const char *Default)
+string LookupTag(const string &Message,const char *Tag,const char *Default)
 {
    // Look for a matching tag.
    int Length = strlen(Tag);
-   for (string::iterator I = Message.begin(); I + Length < Message.end(); I++)
+   for (string::const_iterator I = Message.begin(); I + Length < Message.end(); I++)
    {
       // Found the tag
       if (I[Length] == ':' && stringcasecmp(I,I+Length,Tag) == 0)
       {
 	 // Find the end of line and strip the leading/trailing spaces
-	 string::iterator J;
+	 string::const_iterator J;
 	 I += Length + 1;
 	 for (; isspace(*I) != 0 && I < Message.end(); I++);
 	 for (J = I; *J != '\n' && J < Message.end(); J++);
@@ -572,7 +569,7 @@ string LookupTag(string Message,const char *Tag,const char *Default)
 // ---------------------------------------------------------------------
 /* This inspects the string to see if it is true or if it is false and
    then returns the result. Several varients on true/false are checked. */
-int StringToBool(string Text,int Default)
+int StringToBool(const string &Text,int Default)
 {
    char *End;
    int Res = strtol(Text.c_str(),&End,0);   
@@ -738,7 +735,7 @@ static time_t timegm(struct tm *t)
    'timegm' to convert a struct tm in UTC to a time_t. For some bizzar
    reason the C library does not provide any such function :< This also
    handles the weird, but unambiguous FTP time format*/
-bool StrToTime(string Val,time_t &Result)
+bool StrToTime(const string &Val,time_t &Result)
 {
    struct tm Tm;
    char Month[10];
@@ -825,7 +822,7 @@ static int HexDigit(int c)
 // Hex2Num - Convert a long hex number into a buffer			/*{{{*/
 // ---------------------------------------------------------------------
 /* The length of the buffer must be exactly 1/2 the length of the string. */
-bool Hex2Num(string Str,unsigned char *Num,unsigned int Length)
+bool Hex2Num(const string &Str,unsigned char *Num,unsigned int Length)
 {
    if (Str.length() != Length*2)
       return false;
@@ -986,7 +983,7 @@ char *safe_snprintf(char *Buffer,char *End,const char *Format,...)
 // ---------------------------------------------------------------------
 /* The domain list is a comma seperate list of domains that are suffix
    matched against the argument */
-bool CheckDomainList(string Host,string List)
+bool CheckDomainList(const string &Host,const string &List)
 {
    string::const_iterator Start = List.begin();
    for (string::const_iterator Cur = List.begin(); Cur <= List.end(); Cur++)
@@ -1009,7 +1006,7 @@ bool CheckDomainList(string Host,string List)
 // URI::CopyFrom - Copy from an object					/*{{{*/
 // ---------------------------------------------------------------------
 /* This parses the URI into all of its components */
-void URI::CopyFrom(string U)
+void URI::CopyFrom(const string &U)
 {
    string::const_iterator I = U.begin();
 
@@ -1038,9 +1035,9 @@ void URI::CopyFrom(string U)
       SingleSlash = U.end();
 
    // We can now write the access and path specifiers
-   Access = string(U,0,FirstColon - U.begin());
+   Access.assign(U.begin(),FirstColon);
    if (SingleSlash != U.end())
-      Path = string(U,SingleSlash - U.begin());
+      Path.assign(SingleSlash,U.end());
    if (Path.empty() == true)
       Path = "/";
 
@@ -1070,14 +1067,14 @@ void URI::CopyFrom(string U)
    if (At == SingleSlash)
    {
       if (FirstColon < SingleSlash)
-	 Host = string(U,FirstColon - U.begin(),SingleSlash - FirstColon);
+	 Host.assign(FirstColon,SingleSlash);
    }
    else
    {
-      Host = string(U,At - U.begin() + 1,SingleSlash - At - 1);
-      User = string(U,FirstColon - U.begin(),SecondColon - FirstColon);
+      Host.assign(At+1,SingleSlash);
+      User.assign(FirstColon,SecondColon);
       if (SecondColon < At)
-	 Password = string(U,SecondColon - U.begin() + 1,At - SecondColon - 1);
+	 Password.assign(SecondColon+1,At);
    }   
    
    // Now we parse the RFC 2732 [] hostnames.
@@ -1105,7 +1102,7 @@ void URI::CopyFrom(string U)
    // Tsk, weird.
    if (InBracket == true)
    {
-      Host = string();
+      Host.clear();
       return;
    }
    
@@ -1116,7 +1113,7 @@ void URI::CopyFrom(string U)
       return;
    
    Port = atoi(string(Host,Pos+1).c_str());
-   Host = string(Host,0,Pos);
+   Host.assign(Host,0,Pos);
 }
 									/*}}}*/
 // URI::operator string - Convert the URI to a string			/*{{{*/
@@ -1171,12 +1168,12 @@ URI::operator string()
 // URI::SiteOnly - Return the schema and site for the URI		/*{{{*/
 // ---------------------------------------------------------------------
 /* */
-string URI::SiteOnly(string URI)
+string URI::SiteOnly(const string &URI)
 {
    ::URI U(URI);
-   U.User = string();
-   U.Password = string();
-   U.Path = string();
+   U.User.clear();
+   U.Password.clear();
+   U.Path.clear();
    U.Port = 0;
    return U;
 }
diff --git a/apt-pkg/contrib/strutl.h b/apt-pkg/contrib/strutl.h
index 353e78ac9..6ec2b7811 100644
--- a/apt-pkg/contrib/strutl.h
+++ b/apt-pkg/contrib/strutl.h
@@ -43,24 +43,24 @@ char *_strstrip(char *String);
 char *_strtabexpand(char *String,size_t Len);
 bool ParseQuoteWord(const char *&String,string &Res);
 bool ParseCWord(const char *&String,string &Res);
-string QuoteString(string Str,const char *Bad);
-string DeQuoteString(string Str);
+string QuoteString(const string &Str,const char *Bad);
+string DeQuoteString(const string &Str);
 string SizeToStr(double Bytes);
 string TimeToStr(unsigned long Sec);
-string Base64Encode(string Str);
-string URItoFileName(string URI);
+string Base64Encode(const string &Str);
+string URItoFileName(const string &URI);
 string TimeRFC1123(time_t Date);
-bool StrToTime(string Val,time_t &Result);
-string LookupTag(string Message,const char *Tag,const char *Default = 0);
-int StringToBool(string Text,int Default = -1);
+bool StrToTime(const string &Val,time_t &Result);
+string LookupTag(const string &Message,const char *Tag,const char *Default = 0);
+int StringToBool(const string &Text,int Default = -1);
 bool ReadMessages(int Fd, vector<string> &List);
 bool StrToNum(const char *Str,unsigned long &Res,unsigned Len,unsigned Base = 0);
-bool Hex2Num(string Str,unsigned char *Num,unsigned int Length);
+bool Hex2Num(const string &Str,unsigned char *Num,unsigned int Length);
 bool TokSplitString(char Tok,char *Input,char **List,
 		    unsigned long ListMax);
 void ioprintf(ostream &out,const char *format,...) APT_FORMAT2;
 char *safe_snprintf(char *Buffer,char *End,const char *Format,...) APT_FORMAT3;
-bool CheckDomainList(string Host,string List);
+bool CheckDomainList(const string &Host, const string &List);
 
 #define APT_MKSTRCMP(name,func) \
 inline int name(const char *A,const char *AEnd,const char *B) {return func(A,AEnd,B,B+strlen(B));}; \
@@ -101,7 +101,7 @@ inline const char *DeNull(const char *s) {return (s == 0?"(null)":s);};
 
 class URI
 {
-   void CopyFrom(string From);
+   void CopyFrom(const string &From);
 		 
    public:
    
@@ -113,9 +113,9 @@ class URI
    unsigned int Port;
    
    operator string();
-   inline void operator =(string From) {CopyFrom(From);};
+   inline void operator =(const string &From) {CopyFrom(From);};
    inline bool empty() {return Access.empty();};
-   static string SiteOnly(string URI);
+   static string SiteOnly(const string &URI);
    
    URI(string Path) {CopyFrom(Path);};
    URI() : Port(0) {};
@@ -127,7 +127,7 @@ struct SubstVar
    const string *Contents;
 };
 string SubstVar(string Str,const struct SubstVar *Vars);
-string SubstVar(string Str,string Subst,string Contents);
+string SubstVar(const string &Str,const string &Subst,const string &Contents);
 
 struct RxChoiceList
 {