Bundle relevant parts of sqlite 2.8.0.

# sqlite has a completely non-restrictive license

ext/sqlite/libsqlite/src/encode.c

@@ -0,0 +1,165 @@
+/*
+** 2002 April 25
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains helper routines used to translate binary data into
+** a null-terminated string (suitable for use in SQLite) and back again.
+** These are convenience routines for use by people who want to store binary
+** data in an SQLite database.  The code in this file is not used by any other
+** part of the SQLite library.
+**
+** $Id$
+*/
+#include <string.h>
+
+/*
+** Encode a binary buffer "in" of size n bytes so that it contains
+** no instances of characters '\'' or '\000'.  The output is 
+** null-terminated and can be used as a string value in an INSERT
+** or UPDATE statement.  Use sqlite_decode_binary() to convert the
+** string back into its original binary.
+**
+** The result is written into a preallocated output buffer "out".
+** "out" must be able to hold at least (256*n + 1262)/253 bytes.
+** In other words, the output will be expanded by as much as 3
+** bytes for every 253 bytes of input plus 2 bytes of fixed overhead.
+** (This is approximately 2 + 1.019*n or about a 2% size increase.)
+**
+** The return value is the number of characters in the encoded
+** string, excluding the "\000" terminator.
+*/
+int sqlite_encode_binary(const unsigned char *in, int n, unsigned char *out){
+  int i, j, e, m;
+  int cnt[256];
+  if( n<=0 ){
+    out[0] = 'x';
+    out[1] = 0;
+    return 1;
+  }
+  memset(cnt, 0, sizeof(cnt));
+  for(i=n-1; i>=0; i--){ cnt[in[i]]++; }
+  m = n;
+  for(i=1; i<256; i++){
+    int sum;
+    if( i=='\'' ) continue;
+    sum = cnt[i] + cnt[(i+1)&0xff] + cnt[(i+'\'')&0xff];
+    if( sum<m ){
+      m = sum;
+      e = i;
+      if( m==0 ) break;
+    }
+  }
+  out[0] = e;
+  j = 1;
+  for(i=0; i<n; i++){
+    int c = (in[i] - e)&0xff;
+    if( c==0 ){
+      out[j++] = 1;
+      out[j++] = 1;
+    }else if( c==1 ){
+      out[j++] = 1;
+      out[j++] = 2;
+    }else if( c=='\'' ){
+      out[j++] = 1;
+      out[j++] = 3;
+    }else{
+      out[j++] = c;
+    }
+  }
+  out[j] = 0;
+  return j;
+}
+
+/*
+** Decode the string "in" into binary data and write it into "out".
+** This routine reverses the encoded created by sqlite_encode_binary().
+** The output will always be a few bytes less than the input.  The number
+** of bytes of output is returned.  If the input is not a well-formed
+** encoding, -1 is returned.
+**
+** The "in" and "out" parameters may point to the same buffer in order
+** to decode a string in place.
+*/
+int sqlite_decode_binary(const unsigned char *in, unsigned char *out){
+  int i, c, e;
+  e = *(in++);
+  i = 0;
+  while( (c = *(in++))!=0 ){
+    if( c==1 ){
+      c = *(in++);
+      if( c==1 ){
+        c = 0;
+      }else if( c==2 ){
+        c = 1;
+      }else if( c==3 ){
+        c = '\'';
+      }else{
+        return -1;
+      }
+    }
+    out[i++] = (c + e)&0xff;
+  }
+  return i;
+}
+
+#ifdef ENCODER_TEST
+/*
+** The subroutines above are not tested by the usual test suite.  To test
+** these routines, compile just this one file with a -DENCODER_TEST=1 option
+** and run the result.
+*/
+int main(int argc, char **argv){
+  int i, j, n, m, nOut;
+  unsigned char in[30000];
+  unsigned char out[33000];
+
+  for(i=0; i<sizeof(in); i++){
+    printf("Test %d: ", i+1);
+    n = rand() % (i+1);
+    if( i%100==0 ){
+      int k;
+      for(j=k=0; j<n; j++){
+        /* if( k==0 || k=='\'' ) k++; */
+        in[j] = k;
+        k = (k+1)&0xff;
+      }
+    }else{
+      for(j=0; j<n; j++) in[j] = rand() & 0xff;
+    }
+    nOut = sqlite_encode_binary(in, n, out);
+    if( nOut!=strlen(out) ){
+      printf(" ERROR return value is %d instead of %d\n", nOut, strlen(out));
+      exit(1);
+    }
+    m = (256*n + 1262)/253;
+    printf("size %d->%d (max %d)", n, strlen(out)+1, m);
+    if( strlen(out)+1>m ){
+      printf(" ERROR output too big\n");
+      exit(1);
+    }
+    for(j=0; out[j]; j++){
+      if( out[j]=='\'' ){
+        printf(" ERROR contains (')\n");
+        exit(1);
+      }
+    }
+    j = sqlite_decode_binary(out, out);
+    if( j!=n ){
+      printf(" ERROR decode size %d\n", j);
+      exit(1);
+    }
+    if( memcmp(in, out, n)!=0 ){
+      printf(" ERROR decode mismatch\n");
+      exit(1);
+    }
+    printf(" OK\n");
+  }
+}
+#endif /* ENCODER_TEST */