Add an extension that implements compress() and uncompress() SQL functions.

FossilOrigin-Name: d5c17d1a423321f766616d82c9b27ef87c1d5afd

diff --git a/ext/misc/compress.c b/ext/misc/compress.c
new file mode 100644 (file)
index 0000000..a405911
--- /dev/null
+++ b/ext/misc/compress.c
@@ -0,0 +1,107 @@
+/*
+** 2014-06-13
+**
+** 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 SQLite extension implements SQL compression functions
+** compress() and uncompress() using ZLIB.
+*/
+#include "sqlite3ext.h"
+SQLITE_EXTENSION_INIT1
+#include <zlib.h>
+
+/*
+** Implementation of the "compress(X)" SQL function.  The input X is
+** compressed using zLib and the output is returned.
+**
+** The output is a BLOB that begins with a variable-length integer that
+** is the input size in bytes (the size of X before compression).  The
+** variable-length integer is implemented as 1 to 5 bytes.  There are
+** seven bits per integer stored in the lower seven bits of each byte.
+** More significant bits occur first.  The most significant bit (0x80)
+** is a flag to indicate the end of the integer.
+*/
+static void compressFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  const unsigned char *pIn;
+  unsigned char *pOut;
+  unsigned int nIn;
+  unsigned long int nOut;
+  unsigned char x[8];
+  int i, j;
+
+  pIn = sqlite3_value_blob(argv[0]);
+  nIn = sqlite3_value_bytes(argv[0]);
+  nOut = 13 + nIn + (nIn+999)/1000;
+  pOut = sqlite3_malloc( nOut+5 );
+  for(i=4; i>=0; i--){
+    x[i] = (nIn >> (7*(4-i)))&0x7f;
+  }
+  for(i=0; i<4 && x[i]==0; i++){}
+  for(j=0; i<=4; i++, j++) pOut[j] = x[i];
+  pOut[j-1] |= 0x80;
+  compress(&pOut[j], &nOut, pIn, nIn);
+  sqlite3_result_blob(context, pOut, nOut+j, sqlite3_free);
+}
+
+/*
+** Implementation of the "uncompress(X)" SQL function.  The argument X
+** is a blob which was obtained from compress(Y).  The output will be
+** the value Y.
+*/
+static void uncompressFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  const unsigned char *pIn;
+  unsigned char *pOut;
+  unsigned int nIn;
+  unsigned long int nOut;
+  int rc;
+  int i;
+
+  pIn = sqlite3_value_blob(argv[0]);
+  nIn = sqlite3_value_bytes(argv[0]);
+  nOut = 0;
+  for(i=0; i<nIn && i<5; i++){
+    nOut = (nOut<<7) | (pIn[i]&0x7f);
+    if( (pIn[i]&0x80)!=0 ){ i++; break; }
+  }
+  pOut = sqlite3_malloc( nOut+1 );
+  rc = uncompress(pOut, &nOut, &pIn[i], nIn-i);
+  if( rc==Z_OK ){
+    sqlite3_result_blob(context, pOut, nOut, sqlite3_free);
+  }
+}
+
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int sqlite3_compress_init(
+  sqlite3 *db, 
+  char **pzErrMsg, 
+  const sqlite3_api_routines *pApi
+){
+  int rc = SQLITE_OK;
+  SQLITE_EXTENSION_INIT2(pApi);
+  (void)pzErrMsg;  /* Unused parameter */
+  rc = sqlite3_create_function(db, "compress", 1, SQLITE_UTF8, 0,
+                               compressFunc, 0, 0);
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_create_function(db, "uncompress", 1, SQLITE_UTF8, 0,
+                                 uncompressFunc, 0, 0);
+  }
+  return rc;
+}

diff --git a/manifest b/manifest
index 80147db415062f378669ee127e3345427056491a..87826c081e93fc18574158ff6111f067da4e012d 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Increase\sthe\sWAL-mode\sSQLITE_PROTOCOL\stimeout\sto\s10\sseconds.
-D 2014-06-12T17:10:18.787
+C Add\san\sextension\sthat\simplements\scompress()\sand\suncompress()\sSQL\sfunctions.
+D 2014-06-13T13:08:21.440
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in dd2b1aba364ff9b05de41086f74407f285c57670
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -108,6 +108,7 @@ F ext/icu/icu.c d415ccf984defeb9df2c0e1afcfaa2f6dc05eacb
 F ext/icu/sqliteicu.h 728867a802baa5a96de7495e9689a8e01715ef37
 F ext/misc/amatch.c 678056a4bfcd83c4e82dea81d37543cd1d6dbee1
 F ext/misc/closure.c 636024302cde41b2bf0c542f81c40c624cfb7012
+F ext/misc/compress.c 76e45655f4046e756064ab10c62e18f2eb846b9f
 F ext/misc/fuzzer.c 136533c53cfce0957f0b48fa11dba27e21c5c01d
 F ext/misc/ieee754.c b0362167289170627659e84173f5d2e8fee8566e
 F ext/misc/nextchar.c 35c8b8baacb96d92abbb34a83a997b797075b342
@@ -1174,7 +1175,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 6c68d758bce3752f044752404a76bf3ba3eec48f
-R 2f07fa98b6e908bc6502590dbe40f41c
+P 2aeacf81df92b4fe5d1825c1dc1cd176b8af8bd9
+R d1737f084b807e547e6c83682c2e8d71
 U drh
-Z 7ca1de307211ad47daac93b8be7d2faa
+Z 8447f1843125715fcf2f15ddbc0454fa

diff --git a/manifest.uuid b/manifest.uuid
index f0d84ac5584820081ae4e9e89e7049559d97c9c2..dd7a18f6319a8d6408da69e5576f508a7227d67d 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-2aeacf81df92b4fe5d1825c1dc1cd176b8af8bd9
\ No newline at end of file
+d5c17d1a423321f766616d82c9b27ef87c1d5afd
\ No newline at end of file