SQLite

  $(TOP)/src/date.c \
  $(TOP)/src/func.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pragma.c \
  $(TOP)/src/printf.c \

  $(TOP)/src/test1.c \
  $(TOP)/src/test2.c \
  $(TOP)/src/test3.c \
  $(TOP)/src/test4.c \
  $(TOP)/src/test5.c \
  $(TOP)/src/test6.c \
  $(TOP)/src/test7.c \
  $(TOP)/src/test_async.c \
  $(TOP)/src/test_md5.c \
  $(TOP)/src/test_server.c \
  $(TOP)/src/utf.c \
  $(TOP)/src/util.c \
  $(TOP)/src/vdbe.c \

  $(TOP)/src/where.c

# Header files used by all library source files.
#
HDR = \
   sqlite3.h  \
   $(TOP)/src/btree.h \

  $(TOP)/src/func.c \
  $(TOP)/src/os.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pragma.c \
  $(TOP)/src/printf.c \

  $(TOP)/src/test1.c \
  $(TOP)/src/test2.c \
  $(TOP)/src/test3.c \
  $(TOP)/src/test4.c \
  $(TOP)/src/test5.c \
  $(TOP)/src/test6.c \
  $(TOP)/src/test7.c \
  $(TOP)/src/test_async.c \
  $(TOP)/src/test_md5.c \
  $(TOP)/src/test_server.c \
  $(TOP)/src/utf.c \
  $(TOP)/src/util.c \
  $(TOP)/src/vdbe.c \

  $(TOP)/src/where.c

# Header files used by all library source files.
#
HDR = \
   sqlite3.h  \
   $(TOP)/src/btree.h \

	sed \
	  -e '/^#/d' \
	  -e 's,\\,\\\\,g' \
	  -e 's,",\\",g' \
	  -e 's,^,",' \
	  -e 's,$$,\\n",' \
	  $(TOP)/tool/spaceanal.tcl >spaceanal_tcl.h
	$(TCCX) $(TCL_FLAGS) -DTCLSH=2 -DSQLITE_TEST=1 -DSQLITE_DEBUG=1 -o \
 		sqlite3_analyzer$(EXE) $(TESTSRC) $(TOP)/src/tclsqlite.c \
		libsqlite3.a $(LIBTCL) $(THREADLIB)

# Rules used to build documentation
#
arch.html:	$(TOP)/www/arch.tcl
	tclsh $(TOP)/www/arch.tcl >arch.html

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code to implement the "sqlite" command line
** utility for accessing SQLite databases.
**
** $Id: shell.c,v 1.131 2006/01/25 15:55:38 drh Exp $
*/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <assert.h>
#include "sqlite3.h"
#include <ctype.h>

  "                         tcl      TCL list elements\n"
  ".nullvalue STRING      Print STRING in place of NULL values\n"
  ".output FILENAME       Send output to FILENAME\n"
  ".output stdout         Send output to the screen\n"
  ".prompt MAIN CONTINUE  Replace the standard prompts\n"
  ".quit                  Exit this program\n"
  ".read FILENAME         Execute SQL in FILENAME\n"



  ".schema ?TABLE?        Show the CREATE statements\n"
  ".separator STRING      Change separator used by output mode and .import\n"
  ".show                  Show the current values for various settings\n"
  ".tables ?PATTERN?      List names of tables matching a LIKE pattern\n"
  ".timeout MS            Try opening locked tables for MS milliseconds\n"
  ".width NUM NUM ...     Set column widths for \"column\" mode\n"
;

/* Forward reference */
static void process_input(struct callback_data *p, FILE *in);

/*
** Make sure the database is open.  If it is not, then open it.  If
** the database fails to open, print an error message and exit.
*/
static void open_db(struct callback_data *p){
  if( p->db==0 ){
    sqlite3_open(p->zDbFilename, &p->db);
    db = p->db;



    sqlite3_create_function(db, "shellstatic", 0, SQLITE_UTF8, 0,
        shellstaticFunc, 0, 0);
    if( SQLITE_OK!=sqlite3_errcode(db) ){
      fprintf(stderr,"Unable to open database \"%s\": %s\n", 
          p->zDbFilename, sqlite3_errmsg(db));
      exit(1);
    }

      fprintf(stderr,"can't open \"%s\"\n", azArg[1]);
    }else{
      process_input(p, alt);
      fclose(alt);
    }
  }else

















  if( c=='s' && strncmp(azArg[0], "schema", n)==0 ){
    struct callback_data data;
    char *zErrMsg = 0;
    open_db(p);
    memcpy(&data, p, sizeof(data));
    data.showHeader = 0;
    data.mode = MODE_Semi;

*/
static const char zOptions[] = 
  "   -init filename       read/process named file\n"
  "   -echo                print commands before execution\n"
  "   -[no]header          turn headers on or off\n"
  "   -column              set output mode to 'column'\n"
  "   -html                set output mode to HTML\n"



  "   -line                set output mode to 'line'\n"
  "   -list                set output mode to 'list'\n"
  "   -separator 'x'       set output field separator (|)\n"
  "   -nullvalue 'text'    set text string for NULL values\n"
  "   -version             show SQLite version\n"
  "   -help                show this text, also show dot-commands\n"
;

/*
** SQLite uses this code for testing only.  It is not a part of
** the SQLite library.  This file implements two new TCL commands
** "md5" and "md5file" that compute md5 checksums on arbitrary text
** and on complete files.  These commands are used by the "testfixture"
** program to help verify the correct operation of the SQLite library.
**
** The original use of these TCL commands was to test the ROLLBACK
** feature of SQLite.  First compute the MD5-checksum of the database.
** Then make some changes but rollback the changes rather than commit
** them.  Compute a second MD5-checksum of the file and verify that the
** two checksums are the same.  Such is the original use of this code.
** New uses may have been added since this comment was written.
*/
/*
 * This code implements the MD5 message-digest algorithm.
 * The algorithm is due to Ron Rivest.  This code was
 * written by Colin Plumb in 1993, no copyright is claimed.
 * This code is in the public domain; do with it what you wish.
 *
 * Equivalent code is available from RSA Data Security, Inc.
 * This code has been tested against that, and is equivalent,
 * except that you don't need to include two pages of legalese
 * with every copy.
 *
 * To compute the message digest of a chunk of bytes, declare an
 * MD5Context structure, pass it to MD5Init, call MD5Update as
 * needed on buffers full of bytes, and then call MD5Final, which
 * will fill a supplied 16-byte array with the digest.
 */
#include <tcl.h>
#include <string.h>
#include "sqlite3.h"

/*
 * If compiled on a machine that doesn't have a 32-bit integer,
 * you just set "uint32" to the appropriate datatype for an
 * unsigned 32-bit integer.  For example:
 *
 *       cc -Duint32='unsigned long' md5.c
 *
 */
#ifndef uint32
#  define uint32 unsigned int
#endif

struct Context {
  uint32 buf[4];
  uint32 bits[2];
  unsigned char in[64];
};
typedef char MD5Context[88];

/*
 * Note: this code is harmless on little-endian machines.
 */
static void byteReverse (unsigned char *buf, unsigned longs){
        uint32 t;
        do {
                t = (uint32)((unsigned)buf[3]<<8 | buf[2]) << 16 |
                            ((unsigned)buf[1]<<8 | buf[0]);
                *(uint32 *)buf = t;
                buf += 4;
        } while (--longs);
}
/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
        ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */
static void MD5Transform(uint32 buf[4], const uint32 in[16]){
        register uint32 a, b, c, d;

        a = buf[0];
        b = buf[1];
        c = buf[2];
        d = buf[3];

        MD5STEP(F1, a, b, c, d, in[ 0]+0xd76aa478,  7);
        MD5STEP(F1, d, a, b, c, in[ 1]+0xe8c7b756, 12);
        MD5STEP(F1, c, d, a, b, in[ 2]+0x242070db, 17);
        MD5STEP(F1, b, c, d, a, in[ 3]+0xc1bdceee, 22);
        MD5STEP(F1, a, b, c, d, in[ 4]+0xf57c0faf,  7);
        MD5STEP(F1, d, a, b, c, in[ 5]+0x4787c62a, 12);
        MD5STEP(F1, c, d, a, b, in[ 6]+0xa8304613, 17);
        MD5STEP(F1, b, c, d, a, in[ 7]+0xfd469501, 22);
        MD5STEP(F1, a, b, c, d, in[ 8]+0x698098d8,  7);
        MD5STEP(F1, d, a, b, c, in[ 9]+0x8b44f7af, 12);
        MD5STEP(F1, c, d, a, b, in[10]+0xffff5bb1, 17);
        MD5STEP(F1, b, c, d, a, in[11]+0x895cd7be, 22);
        MD5STEP(F1, a, b, c, d, in[12]+0x6b901122,  7);
        MD5STEP(F1, d, a, b, c, in[13]+0xfd987193, 12);
        MD5STEP(F1, c, d, a, b, in[14]+0xa679438e, 17);
        MD5STEP(F1, b, c, d, a, in[15]+0x49b40821, 22);

        MD5STEP(F2, a, b, c, d, in[ 1]+0xf61e2562,  5);
        MD5STEP(F2, d, a, b, c, in[ 6]+0xc040b340,  9);
        MD5STEP(F2, c, d, a, b, in[11]+0x265e5a51, 14);
        MD5STEP(F2, b, c, d, a, in[ 0]+0xe9b6c7aa, 20);
        MD5STEP(F2, a, b, c, d, in[ 5]+0xd62f105d,  5);
        MD5STEP(F2, d, a, b, c, in[10]+0x02441453,  9);
        MD5STEP(F2, c, d, a, b, in[15]+0xd8a1e681, 14);
        MD5STEP(F2, b, c, d, a, in[ 4]+0xe7d3fbc8, 20);
        MD5STEP(F2, a, b, c, d, in[ 9]+0x21e1cde6,  5);
        MD5STEP(F2, d, a, b, c, in[14]+0xc33707d6,  9);
        MD5STEP(F2, c, d, a, b, in[ 3]+0xf4d50d87, 14);
        MD5STEP(F2, b, c, d, a, in[ 8]+0x455a14ed, 20);
        MD5STEP(F2, a, b, c, d, in[13]+0xa9e3e905,  5);
        MD5STEP(F2, d, a, b, c, in[ 2]+0xfcefa3f8,  9);
        MD5STEP(F2, c, d, a, b, in[ 7]+0x676f02d9, 14);
        MD5STEP(F2, b, c, d, a, in[12]+0x8d2a4c8a, 20);

        MD5STEP(F3, a, b, c, d, in[ 5]+0xfffa3942,  4);
        MD5STEP(F3, d, a, b, c, in[ 8]+0x8771f681, 11);
        MD5STEP(F3, c, d, a, b, in[11]+0x6d9d6122, 16);
        MD5STEP(F3, b, c, d, a, in[14]+0xfde5380c, 23);
        MD5STEP(F3, a, b, c, d, in[ 1]+0xa4beea44,  4);
        MD5STEP(F3, d, a, b, c, in[ 4]+0x4bdecfa9, 11);
        MD5STEP(F3, c, d, a, b, in[ 7]+0xf6bb4b60, 16);
        MD5STEP(F3, b, c, d, a, in[10]+0xbebfbc70, 23);
        MD5STEP(F3, a, b, c, d, in[13]+0x289b7ec6,  4);
        MD5STEP(F3, d, a, b, c, in[ 0]+0xeaa127fa, 11);
        MD5STEP(F3, c, d, a, b, in[ 3]+0xd4ef3085, 16);
        MD5STEP(F3, b, c, d, a, in[ 6]+0x04881d05, 23);
        MD5STEP(F3, a, b, c, d, in[ 9]+0xd9d4d039,  4);
        MD5STEP(F3, d, a, b, c, in[12]+0xe6db99e5, 11);
        MD5STEP(F3, c, d, a, b, in[15]+0x1fa27cf8, 16);
        MD5STEP(F3, b, c, d, a, in[ 2]+0xc4ac5665, 23);

        MD5STEP(F4, a, b, c, d, in[ 0]+0xf4292244,  6);
        MD5STEP(F4, d, a, b, c, in[ 7]+0x432aff97, 10);
        MD5STEP(F4, c, d, a, b, in[14]+0xab9423a7, 15);
        MD5STEP(F4, b, c, d, a, in[ 5]+0xfc93a039, 21);
        MD5STEP(F4, a, b, c, d, in[12]+0x655b59c3,  6);
        MD5STEP(F4, d, a, b, c, in[ 3]+0x8f0ccc92, 10);
        MD5STEP(F4, c, d, a, b, in[10]+0xffeff47d, 15);
        MD5STEP(F4, b, c, d, a, in[ 1]+0x85845dd1, 21);
        MD5STEP(F4, a, b, c, d, in[ 8]+0x6fa87e4f,  6);
        MD5STEP(F4, d, a, b, c, in[15]+0xfe2ce6e0, 10);
        MD5STEP(F4, c, d, a, b, in[ 6]+0xa3014314, 15);
        MD5STEP(F4, b, c, d, a, in[13]+0x4e0811a1, 21);
        MD5STEP(F4, a, b, c, d, in[ 4]+0xf7537e82,  6);
        MD5STEP(F4, d, a, b, c, in[11]+0xbd3af235, 10);
        MD5STEP(F4, c, d, a, b, in[ 2]+0x2ad7d2bb, 15);
        MD5STEP(F4, b, c, d, a, in[ 9]+0xeb86d391, 21);

        buf[0] += a;
        buf[1] += b;
        buf[2] += c;
        buf[3] += d;
}

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
static void MD5Init(MD5Context *pCtx){
        struct Context *ctx = (struct Context *)pCtx;
        ctx->buf[0] = 0x67452301;
        ctx->buf[1] = 0xefcdab89;
        ctx->buf[2] = 0x98badcfe;
        ctx->buf[3] = 0x10325476;
        ctx->bits[0] = 0;
        ctx->bits[1] = 0;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
static 
void MD5Update(MD5Context *pCtx, const unsigned char *buf, unsigned int len){
        struct Context *ctx = (struct Context *)pCtx;
        uint32 t;

        /* Update bitcount */

        t = ctx->bits[0];
        if ((ctx->bits[0] = t + ((uint32)len << 3)) < t)
                ctx->bits[1]++; /* Carry from low to high */
        ctx->bits[1] += len >> 29;

        t = (t >> 3) & 0x3f;    /* Bytes already in shsInfo->data */

        /* Handle any leading odd-sized chunks */

        if ( t ) {
                unsigned char *p = (unsigned char *)ctx->in + t;

                t = 64-t;
                if (len < t) {
                        memcpy(p, buf, len);
                        return;
                }
                memcpy(p, buf, t);
                byteReverse(ctx->in, 16);
                MD5Transform(ctx->buf, (uint32 *)ctx->in);
                buf += t;
                len -= t;
        }

        /* Process data in 64-byte chunks */

        while (len >= 64) {
                memcpy(ctx->in, buf, 64);
                byteReverse(ctx->in, 16);
                MD5Transform(ctx->buf, (uint32 *)ctx->in);
                buf += 64;
                len -= 64;
        }

        /* Handle any remaining bytes of data. */

        memcpy(ctx->in, buf, len);
}

/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern 
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
static void MD5Final(unsigned char digest[16], MD5Context *pCtx){
        struct Context *ctx = (struct Context *)pCtx;
        unsigned count;
        unsigned char *p;

        /* Compute number of bytes mod 64 */
        count = (ctx->bits[0] >> 3) & 0x3F;

        /* Set the first char of padding to 0x80.  This is safe since there is
           always at least one byte free */
        p = ctx->in + count;
        *p++ = 0x80;

        /* Bytes of padding needed to make 64 bytes */
        count = 64 - 1 - count;

        /* Pad out to 56 mod 64 */
        if (count < 8) {
                /* Two lots of padding:  Pad the first block to 64 bytes */
                memset(p, 0, count);
                byteReverse(ctx->in, 16);
                MD5Transform(ctx->buf, (uint32 *)ctx->in);

                /* Now fill the next block with 56 bytes */
                memset(ctx->in, 0, 56);
        } else {
                /* Pad block to 56 bytes */
                memset(p, 0, count-8);
        }
        byteReverse(ctx->in, 14);

        /* Append length in bits and transform */
        ((uint32 *)ctx->in)[ 14 ] = ctx->bits[0];
        ((uint32 *)ctx->in)[ 15 ] = ctx->bits[1];

        MD5Transform(ctx->buf, (uint32 *)ctx->in);
        byteReverse((unsigned char *)ctx->buf, 4);
        memcpy(digest, ctx->buf, 16);
        memset(ctx, 0, sizeof(ctx));    /* In case it's sensitive */
}

/*
** Convert a digest into base-16.  digest should be declared as
** "unsigned char digest[16]" in the calling function.  The MD5
** digest is stored in the first 16 bytes.  zBuf should
** be "char zBuf[33]".
*/
static void DigestToBase16(unsigned char *digest, char *zBuf){
  static char const zEncode[] = "0123456789abcdef";
  int i, j;

  for(j=i=0; i<16; i++){
    int a = digest[i];
    zBuf[j++] = zEncode[(a>>4)&0xf];
    zBuf[j++] = zEncode[a & 0xf];
  }
  zBuf[j] = 0;
}

/*
** A TCL command for md5.  The argument is the text to be hashed.  The
** Result is the hash in base64.  
*/
static int md5_cmd(void*cd, Tcl_Interp *interp, int argc, const char **argv){
  MD5Context ctx;
  unsigned char digest[16];

  if( argc!=2 ){
    Tcl_AppendResult(interp,"wrong # args: should be \"", argv[0], 
        " TEXT\"", 0);
    return TCL_ERROR;
  }
  MD5Init(&ctx);
  MD5Update(&ctx, (unsigned char*)argv[1], (unsigned)strlen(argv[1]));
  MD5Final(digest, &ctx);
  DigestToBase16(digest, interp->result);
  return TCL_OK;
}

/*
** A TCL command to take the md5 hash of a file.  The argument is the
** name of the file.
*/
static int md5file_cmd(void*cd, Tcl_Interp*interp, int argc, const char **argv){
  FILE *in;
  MD5Context ctx;
  unsigned char digest[16];
  char zBuf[10240];

  if( argc!=2 ){
    Tcl_AppendResult(interp,"wrong # args: should be \"", argv[0], 
        " FILENAME\"", 0);
    return TCL_ERROR;
  }
  in = fopen(argv[1],"rb");
  if( in==0 ){
    Tcl_AppendResult(interp,"unable to open file \"", argv[1], 
         "\" for reading", 0);
    return TCL_ERROR;
  }
  MD5Init(&ctx);
  for(;;){
    int n;
    n = fread(zBuf, 1, sizeof(zBuf), in);
    if( n<=0 ) break;
    MD5Update(&ctx, (unsigned char*)zBuf, (unsigned)n);
  }
  fclose(in);
  MD5Final(digest, &ctx);
  DigestToBase16(digest, interp->result);
  return TCL_OK;
}

/*
** Register the two TCL commands above with the TCL interpreter.
*/
int Md5_Init(Tcl_Interp *interp){
  Tcl_CreateCommand(interp, "md5", (Tcl_CmdProc*)md5_cmd, 0, 0);
  Tcl_CreateCommand(interp, "md5file", (Tcl_CmdProc*)md5file_cmd, 0, 0);
  return TCL_OK;
}

/*
** During testing, the special md5sum() aggregate function is available.
** inside SQLite.  The following routines implement that function.
*/
static void md5step(sqlite3_context *context, int argc, sqlite3_value **argv){
  MD5Context *p;
  int i;
  if( argc<1 ) return;
  p = sqlite3_aggregate_context(context, sizeof(*p));
  if( p==0 ) return;
  if( sqlite3_aggregate_count(context)==1 ){
    MD5Init(p);
  }
  for(i=0; i<argc; i++){
    const char *zData = (char*)sqlite3_value_text(argv[i]);
    if( zData ){
      MD5Update(p, (unsigned char*)zData, strlen(zData));
    }
  }
}
static void md5finalize(sqlite3_context *context){
  MD5Context *p;
  unsigned char digest[16];
  char zBuf[33];
  p = sqlite3_aggregate_context(context, sizeof(*p));
  MD5Final(digest,p);
  DigestToBase16(digest, zBuf);
  sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
}
void Md5_Register(sqlite3 *db){
  sqlite3_create_function(db, "md5sum", -1, SQLITE_UTF8, 0, 0, 
      md5step, md5finalize);
}

/*
** 2006 January 07
**
** 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 demonstration code.  Nothing in this file gets compiled
** or linked into the SQLite library unless you use a non-standard option:
**
**      -DSQLITE_SERVER=1
**
** The configure script will never generate a Makefile with the option
** above.  You will need to manually modify the Makefile if you want to
** include any of the code from this file in your project.  Or, at your
** option, you may copy and paste the code from this file and
** thereby avoiding a recompile of SQLite.
**
**
** This source file demonstrates how to use SQLite to create an SQL database 
** server thread in a multiple-threaded program.  One or more client threads
** send messages to the server thread and the server thread processes those
** messages in the order received and returns the results to the client.
**
** One might ask:  "Why bother?  Why not just let each thread connect
** to the database directly?"  There are a several of reasons to
** prefer the client/server approach.
**
**    (1)  Some systems (ex: Redhat9) have broken threading implementations
**         that prevent SQLite database connections from being used in
**         a thread different from the one where they were created.  With
**         the client/server approach, all database connections are created
**         and used within the server thread.  Client calls to the database
**         can be made from multiple threads (though not at the same time!)
**
**    (2)  Beginning with SQLite version 3.3.0, when two or more 
**         connections to the same database occur within the same thread,
**         they can optionally share their database cache.  This reduces
**         I/O and memory requirements.  Cache shared is controlled using
**         the sqlite3_enable_shared_cache() API.
**
**    (3)  Database connections on a shared cache use table-level locking
**         instead of file-level locking for improved concurrency.
**
**    (4)  Database connections on a shared cache can by optionally
**         set to READ UNCOMMITTED isolation.  (The default isolation for
**         SQLite is SERIALIZABLE.)  When this occurs, readers will
**         never be blocked by a writer and writers will not be
**         blocked by readers.  There can still only be a single writer
**         at a time, but multiple readers can simultaneously exist with
**         that writer.  This is a huge increase in concurrency.
**
** To summarize the rational for using a client/server approach: prior
** to SQLite version 3.3.0 it probably was not worth the trouble.  But
** with SQLite version 3.3.0 and beyond you can get significant performance
** and concurrency improvements and memory usage reductions by going
** client/server.
**
** Note:  The extra features of version 3.3.0 described by points (2)
** through (4) above are only available if you compile without the
** option -DSQLITE_OMIT_SHARED_CACHE. 
**
** Here is how the client/server approach works:  The database server
** thread is started on this procedure:
**
**       void *sqlite3_server(void *NotUsed);
**
** The sqlite_server procedure runs as long as the g.serverHalt variable
** is false.  A mutex is used to make sure no more than one server runs
** at a time.  The server waits for messages to arrive on a message
** queue and processes the messages in order.
**
** Two convenience routines are provided for starting and stopping the
** server thread:
**
**       void sqlite3_server_start(void);
**       void sqlite3_server_stop(void);
**
** Both of the convenience routines return immediately.  Neither will
** ever give an error.  If a server is already started or already halted,
** then the routines are effectively no-ops.
**
** Clients use the following interfaces:
**
**       sqlite3_client_open
**       sqlite3_client_prepare
**       sqlite3_client_step
**       sqlite3_client_reset
**       sqlite3_client_finalize
**       sqlite3_client_close
**
** These interfaces work exactly like the standard core SQLite interfaces
** having the same names without the "_client_" infix.  Many other SQLite
** interfaces can be used directly without having to send messages to the
** server as long as SQLITE_ENABLE_MEMORY_MANAGEMENT is not defined.
** The following interfaces fall into this second category:
**
**       sqlite3_bind_*
**       sqlite3_changes
**       sqlite3_clear_bindings
**       sqlite3_column_*
**       sqlite3_complete
**       sqlite3_create_collation
**       sqlite3_create_function
**       sqlite3_data_count
**       sqlite3_db_handle
**       sqlite3_errcode
**       sqlite3_errmsg
**       sqlite3_last_insert_rowid
**       sqlite3_total_changes
**       sqlite3_transfer_bindings
**
** A single SQLite connection (an sqlite3* object) or an SQLite statement
** (an sqlite3_stmt* object) should only be passed to a single interface
** function at a time.  The connections and statements can be passed from
** any thread to any of the functions listed in the second group above as
** long as the same connection is not in use by two threads at once and
** as long as SQLITE_ENABLE_MEMORY_MANAGEMENT is not defined.  Additional
** information about the SQLITE_ENABLE_MEMORY_MANAGEMENT constraint is
** below.
**
** The busy handler for all database connections should remain turned
** off.  That means that any lock contention will cause the associated
** sqlite3_client_step() call to return immediately with an SQLITE_BUSY
** error code.  If a busy handler is enabled and lock contention occurs,
** then the entire server thread will block.  This will cause not only
** the requesting client to block but every other database client as
** well.  It is possible to enhance the code below so that lock
** contention will cause the message to be placed back on the top of
** the queue to be tried again later.  But such enhanced processing is
** not included here, in order to keep the example simple.
**
** This example code assumes the use of pthreads.  Pthreads
** implementations are available for windows.  (See, for example
** http://sourceware.org/pthreads-win32/announcement.html.)  Or, you
** can translate the locking and thread synchronization code to use
** windows primitives easily enough.  The details are left as an
** exercise to the reader.
**
**** Restrictions Associated With SQLITE_ENABLE_MEMORY_MANAGEMENT ****
**
** If you compile with SQLITE_ENABLE_MEMORY_MANAGEMENT defined, then
** SQLite includes code that tracks how much memory is being used by
** each thread.  These memory counts can become confused if memory
** is allocated by one thread and then freed by another.  For that
** reason, when SQLITE_ENABLE_MEMORY_MANAGEMENT is used, all operations
** that might allocate or free memory should be performanced in the same
** thread that originally created the database connection.  In that case,
** many of the operations that are listed above as safe to be performed
** in separate threads would need to be sent over to the server to be
** done there.  If SQLITE_ENABLE_MEMORY_MANAGEMENT is defined, then
** the following functions can be used safely from different threads
** without messing up the allocation counts:
**
**       sqlite3_bind_parameter_name
**       sqlite3_bind_parameter_index
**       sqlite3_changes
**       sqlite3_column_blob
**       sqlite3_column_count
**       sqlite3_complete
**       sqlite3_data_count
**       sqlite3_db_handle
**       sqlite3_errcode
**       sqlite3_errmsg
**       sqlite3_last_insert_rowid
**       sqlite3_total_changes
**
** The remaining functions are not thread-safe when memory management
** is enabled.  So one would have to define some new interface routines
** along the following lines:
**
**       sqlite3_client_bind_*
**       sqlite3_client_clear_bindings
**       sqlite3_client_column_*
**       sqlite3_client_create_collation
**       sqlite3_client_create_function
**       sqlite3_client_transfer_bindings
**
** The example code in this file is intended for use with memory
** management turned off.  So the implementation of these additional
** client interfaces is left as an exercise to the reader.
**
** It may seem surprising to the reader that the list of safe functions
** above does not include things like sqlite3_bind_int() or
** sqlite3_column_int().  But those routines might, in fact, allocate
** or deallocate memory.  In the case of sqlite3_bind_int(), if the
** parameter was previously bound to a string that string might need
** to be deallocated before the new integer value is inserted.  In
** the case of sqlite3_column_int(), the value of the column might be
** a UTF-16 string which will need to be converted to UTF-8 then into
** an integer.
*/

/*
** Only compile the code in this file on UNIX with a THREADSAFE build
** and only if the SQLITE_SERVER macro is defined.
*/
#ifdef SQLITE_SERVER
#if defined(OS_UNIX) && OS_UNIX && defined(THREADSAFE) && THREADSAFE

/*
** We require only pthreads and the public interface of SQLite.
*/
#include <pthread.h>
#include "sqlite3.h"

/*
** Messages are passed from client to server and back again as 
** instances of the following structure.
*/
typedef struct SqlMessage SqlMessage;
struct SqlMessage {
  int op;                      /* Opcode for the message */
  sqlite3 *pDb;                /* The SQLite connection */
  sqlite3_stmt *pStmt;         /* A specific statement */
  int errCode;                 /* Error code returned */
  const char *zIn;             /* Input filename or SQL statement */
  int nByte;                   /* Size of the zIn parameter for prepare() */
  const char *zOut;            /* Tail of the SQL statement */
  SqlMessage *pNext;           /* Next message in the queue */
  SqlMessage *pPrev;           /* Previous message in the queue */
  pthread_mutex_t clientMutex; /* Hold this mutex to access the message */
  pthread_cond_t clientWakeup; /* Signal to wake up the client */
};

/*
** Legal values for SqlMessage.op
*/
#define MSG_Open       1  /* sqlite3_open(zIn, &pDb) */
#define MSG_Prepare    2  /* sqlite3_prepare(pDb, zIn, nByte, &pStmt, &zOut) */
#define MSG_Step       3  /* sqlite3_step(pStmt) */
#define MSG_Reset      4  /* sqlite3_reset(pStmt) */
#define MSG_Finalize   5  /* sqlite3_finalize(pStmt) */
#define MSG_Close      6  /* sqlite3_close(pDb) */
#define MSG_Done       7  /* Server has finished with this message */


/*
** State information about the server is stored in a static variable
** named "g" as follows:
*/
static struct ServerState {
  pthread_mutex_t queueMutex;   /* Hold this mutex to access the msg queue */
  pthread_mutex_t serverMutex;  /* Held by the server while it is running */
  pthread_cond_t serverWakeup;  /* Signal this condvar to wake up the server */
  volatile int serverHalt;      /* Server halts itself when true */
  SqlMessage *pQueueHead;       /* Head of the message queue */
  SqlMessage *pQueueTail;       /* Tail of the message queue */
} g = {
  PTHREAD_MUTEX_INITIALIZER,
  PTHREAD_MUTEX_INITIALIZER,
  PTHREAD_COND_INITIALIZER,
};

/*
** Send a message to the server.  Block until we get a reply.
**
** The mutex and condition variable in the message are uninitialized
** when this routine is called.  This routine takes care of 
** initializing them and destroying them when it has finished.
*/
static void sendToServer(SqlMessage *pMsg){
  /* Initialize the mutex and condition variable on the message
  */
  pthread_mutex_init(&pMsg->clientMutex, 0);
  pthread_cond_init(&pMsg->clientWakeup, 0);

  /* Add the message to the head of the server's message queue.
  */
  pthread_mutex_lock(&g.queueMutex);
  pMsg->pNext = g.pQueueHead;
  if( g.pQueueHead==0 ){
    g.pQueueTail = pMsg;
  }else{
    g.pQueueHead->pPrev = pMsg;
  }
  pMsg->pPrev = 0;
  g.pQueueHead = pMsg;
  pthread_mutex_unlock(&g.queueMutex);

  /* Signal the server that the new message has be queued, then
  ** block waiting for the server to process the message.
  */
  pthread_mutex_lock(&pMsg->clientMutex);
  pthread_cond_signal(&g.serverWakeup);
  while( pMsg->op!=MSG_Done ){
    pthread_cond_wait(&pMsg->clientWakeup, &pMsg->clientMutex);
  }
  pthread_mutex_unlock(&pMsg->clientMutex);

  /* Destroy the mutex and condition variable of the message.
  */
  pthread_mutex_destroy(&pMsg->clientMutex);
  pthread_cond_destroy(&pMsg->clientWakeup);
}

/*
** The following 6 routines are client-side implementations of the
** core SQLite interfaces:
**
**        sqlite3_open
**        sqlite3_prepare
**        sqlite3_step
**        sqlite3_reset
**        sqlite3_finalize
**        sqlite3_close
**
** Clients should use the following client-side routines instead of 
** the core routines above.
**
**        sqlite3_client_open
**        sqlite3_client_prepare
**        sqlite3_client_step
**        sqlite3_client_reset
**        sqlite3_client_finalize
**        sqlite3_client_close
**
** Each of these routines creates a message for the desired operation,
** sends that message to the server, waits for the server to process
** then message and return a response.
*/
int sqlite3_client_open(const char *zDatabaseName, sqlite3 **ppDb){
  SqlMessage msg;
  msg.op = MSG_Open;
  msg.zIn = zDatabaseName;
  sendToServer(&msg);
  *ppDb = msg.pDb;
  return msg.errCode;
}
int sqlite3_client_prepare(
  sqlite3 *pDb,
  const char *zSql,
  int nByte,
  sqlite3_stmt **ppStmt,
  const char **pzTail
){
  SqlMessage msg;
  msg.op = MSG_Prepare;
  msg.pDb = pDb;
  msg.zIn = zSql;
  msg.nByte = nByte;
  sendToServer(&msg);
  *ppStmt = msg.pStmt;
  if( pzTail ) *pzTail = msg.zOut;
  return msg.errCode;
}
int sqlite3_client_step(sqlite3_stmt *pStmt){
  SqlMessage msg;
  msg.op = MSG_Step;
  msg.pStmt = pStmt;
  sendToServer(&msg);
  return msg.errCode;
}
int sqlite3_client_reset(sqlite3_stmt *pStmt){
  SqlMessage msg;
  msg.op = MSG_Reset;
  msg.pStmt = pStmt;
  sendToServer(&msg);
  return msg.errCode;
}
int sqlite3_client_finalize(sqlite3_stmt *pStmt){
  SqlMessage msg;
  msg.op = MSG_Finalize;
  msg.pStmt = pStmt;
  sendToServer(&msg);
  return msg.errCode;
}
int sqlite3_client_close(sqlite3 *pDb){
  SqlMessage msg;
  msg.op = MSG_Close;
  msg.pDb = pDb;
  sendToServer(&msg);
  return msg.errCode;
}

/*
** This routine implements the server.  To start the server, first
** make sure g.serverHalt is false, then create a new detached thread
** on this procedure.  See the sqlite3_server_start() routine below
** for an example.  This procedure loops until g.serverHalt becomes
** true.
*/
void *sqlite3_server(void *NotUsed){
  sqlite3_enable_shared_cache(1);
  if( pthread_mutex_trylock(&g.serverMutex) ){
    sqlite3_enable_shared_cache(0);
    return 0;  /* Another server is already running */
  }
  while( !g.serverHalt ){
    SqlMessage *pMsg;

    /* Remove the last message from the message queue.
    */
    pthread_mutex_lock(&g.queueMutex);
    while( g.pQueueTail==0 && g.serverHalt==0 ){
      pthread_cond_wait(&g.serverWakeup, &g.queueMutex);
    }
    pMsg = g.pQueueTail;
    if( pMsg ){
      if( pMsg->pPrev ){
        pMsg->pPrev->pNext = 0;
      }else{
        g.pQueueHead = 0;
      }
      g.pQueueTail = pMsg->pPrev;
    }
    pthread_mutex_unlock(&g.queueMutex);
    if( pMsg==0 ) break;

    /* Process the message just removed
    */
    pthread_mutex_lock(&pMsg->clientMutex);
    switch( pMsg->op ){
      case MSG_Open: {
        pMsg->errCode = sqlite3_open(pMsg->zIn, &pMsg->pDb);
        break;
      }
      case MSG_Prepare: {
        pMsg->errCode = sqlite3_prepare(pMsg->pDb, pMsg->zIn, pMsg->nByte,
                                        &pMsg->pStmt, &pMsg->zOut);
        break;
      }
      case MSG_Step: {
        pMsg->errCode = sqlite3_step(pMsg->pStmt);
        break;
      }
      case MSG_Reset: {
        pMsg->errCode = sqlite3_reset(pMsg->pStmt);
        break;
      }
      case MSG_Finalize: {
        pMsg->errCode = sqlite3_finalize(pMsg->pStmt);
        break;
      }
      case MSG_Close: {
        pMsg->errCode = sqlite3_close(pMsg->pDb);
        break;
      }
    }

    /* Signal the client that the message has been processed.
    */
    pMsg->op = MSG_Done;
    pthread_mutex_unlock(&pMsg->clientMutex);
    pthread_cond_signal(&pMsg->clientWakeup);
  }
  pthread_mutex_unlock(&g.serverMutex);
  sqlite3_thread_cleanup();
  return 0;
}

/*
** Start a server thread if one is not already running.  If there
** is aleady a server thread running, the new thread will quickly
** die and this routine is effectively a no-op.
*/
void sqlite3_server_start(void){
  pthread_t x;
  int rc;
  g.serverHalt = 0;
  rc = pthread_create(&x, 0, sqlite3_server, 0);
  if( rc==0 ){
    pthread_detach(x);
  }
}

/*
** If a server thread is running, then stop it.  If no server is
** running, this routine is effectively a no-op.
**
** This routine returns immediately without waiting for the server
** thread to stop.  But be assured that the server will eventually stop.
*/
void sqlite3_server_stop(void){
  g.serverHalt = 1;
  pthread_cond_broadcast(&g.serverWakeup);
}

#endif /* defined(OS_UNIX) && OS_UNIX && defined(THREADSAFE) && THREADSAFE */
#endif /* defined(SQLITE_SERVER) */