SQLite

/*
** 2016-06-07
**
** 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 is a utility program that computes an SHA1 hash on the content
** of an SQLite database.
**
** The hash is computed over just the content of the database.  Free
** space inside of the database file, and alternative on-disk representations
** of the same content (ex: UTF8 vs UTF16) do not affect the hash.  So,
** for example, the database file page size, encoding, and auto_vacuum setting
** can all be changed without changing the hash.

};

/*
** All global variables are gathered into the "g" singleton.
*/
struct GlobalVars {
  const char *zArgv0;       /* Name of program */

  unsigned fDebug;          /* Debug flags */
  sqlite3 *db;              /* The database connection */
  SHA1Context cx;           /* SHA1 hash context */
} g;

/*
** Debugging flags
*/
#define DEBUG_FULLTRACE   0x00000001   /* Trace hash to stderr */

/******************************************************************************
** The Hash Engine
**
** Modify these routines (and appropriate state fields in global variable 'g')
** in order to compute a different (better?) hash of the database.
*/
/*

    i = 0;
  }
  (void)memcpy(&g.cx.buffer[j], &data[i], len - i);
}


/* Add padding and compute and output the message digest. */
static void hash_finish(const char *zName){
  unsigned int i;
  unsigned char finalcount[8];
  unsigned char digest[20];
  static const char zEncode[] = "0123456789abcdef";
  char zOut[40];

  for (i = 0; i < 8; i++){

    digest[i] = (unsigned char)((g.cx.state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);
  }
  for(i=0; i<20; i++){
    zOut[i*2] = zEncode[(digest[i]>>4)&0xf];
    zOut[i*2+1] = zEncode[digest[i] & 0xf];
  }
  zOut[i*2]= 0;
  printf("%s %s\n", zOut, zName);
}
/* End of the hashing logic
*******************************************************************************/
  
/*
** Print an error resulting from faulting command-line arguments and
** abort the program.

  va_start(ap, zFormat);
  pStmt = db_vprepare(zFormat, ap);
  va_end(ap);
  return pStmt;
}

/*
** Compute the hash for all rows of the query formed from the printf-style
** zFormat and its argument.
*/
static void hash_one_query(const char *zFormat, ...){
  va_list ap;
  sqlite3_stmt *pStmt;        /* The query defined by zFormat and "..." */
  int nCol;                   /* Number of columns in the result set */
  int i;                      /* Loop counter */

  /* Prepare the query defined by zFormat and "..." */
  va_start(ap, zFormat);
  pStmt = db_vprepare(zFormat, ap);
  va_end(ap);
  nCol = sqlite3_column_count(pStmt);

  /* Compute a hash over the result of the query */
  while( SQLITE_ROW==sqlite3_step(pStmt) ){
    for(i=0; i<nCol; i++){
      switch( sqlite3_column_type(pStmt,i) ){
        case SQLITE_NULL: {
          hash_step((const unsigned char*)"0",1);
          if( g.fDebug & DEBUG_FULLTRACE ) fprintf(stderr, "NULL\n");
          break;
        }
        case SQLITE_INTEGER: {
          sqlite3_uint64 u;
          int j;
          unsigned char x[8];
          sqlite3_int64 v = sqlite3_column_int64(pStmt,i);
          memcpy(&u, &v, 8);
          for(j=7; j>=0; j--){
            x[j] = u & 0xff;
            u >>= 8;
          }
          hash_step((const unsigned char*)"1",1);
          hash_step(x,8);
          if( g.fDebug & DEBUG_FULLTRACE ){
            fprintf(stderr, "INT %s\n", sqlite3_column_text(pStmt,i));
          }
          break;
        }
        case SQLITE_FLOAT: {
          sqlite3_uint64 u;
          int j;
          unsigned char x[8];
          double r = sqlite3_column_double(pStmt,i);
          memcpy(&u, &r, 8);
          for(j=7; j>=0; j--){
            x[j] = u & 0xff;
            u >>= 8;
          }
          hash_step((const unsigned char*)"2",1);
          hash_step(x,8);
          if( g.fDebug & DEBUG_FULLTRACE ){
            fprintf(stderr, "FLOAT %s\n", sqlite3_column_text(pStmt,i));
          }
          break;
        }
        case SQLITE_TEXT: {
          int n = sqlite3_column_bytes(pStmt, i);
          const unsigned char *z = sqlite3_column_text(pStmt, i);
          hash_step((const unsigned char*)"3", 1);
          hash_step(z, n);
          if( g.fDebug & DEBUG_FULLTRACE ){
            fprintf(stderr, "TEXT '%s'\n", sqlite3_column_text(pStmt,i));
          }
          break;
        }
        case SQLITE_BLOB: {
          int n = sqlite3_column_bytes(pStmt, i);
          const unsigned char *z = sqlite3_column_blob(pStmt, i);
          hash_step((const unsigned char*)"4", 1);
          hash_step(z, n);
          if( g.fDebug & DEBUG_FULLTRACE ){
            fprintf(stderr, "BLOB (%d bytes)\n", n);
          }
          break;
        }
      }
    }
  }
  sqlite3_finalize(pStmt);
}


/*
** Print sketchy documentation for this utility program
*/
static void showHelp(void){
  printf("Usage: %s [options] FILE ...\n", g.zArgv0);
  printf(
"Compute a SHA1 hash on the content of database FILE.  System tables such as\n"
"sqlite_stat1, sqlite_stat4, and sqlite_sequence are omitted from the hash.\n"
"Options:\n"
"   --debug N           Set debugging flags to N (experts only)\n"
"   --like PATTERN      Only hash tables whose name is LIKE the pattern\n"
"   --schema-only       Only hash the schema - omit table content\n"
"   --without-schema    Only hash table content - omit the schema\n"
  );
}

int main(int argc, char **argv){
  const char *zDb = 0;         /* Name of the database currently being hashed */
  int i;                       /* Loop counter */
  int rc;                      /* Subroutine return code */
  char *zErrMsg;               /* Error message when opening database */
  sqlite3_stmt *pStmt;         /* An SQLite query */
  const char *zLike = 0;       /* LIKE pattern of tables to hash */
  int omitSchema = 0;          /* True to compute hash on content only */
  int omitContent = 0;         /* True to compute hash on schema only */
  int nFile = 0;               /* Number of input filenames seen */

  g.zArgv0 = argv[0];
  sqlite3_config(SQLITE_CONFIG_SINGLETHREAD);
  for(i=1; i<argc; i++){
    const char *z = argv[i];
    if( z[0]=='-' ){
      z++;
      if( z[0]=='-' ) z++;
      if( strcmp(z,"debug")==0 ){
        if( i==argc-1 ) cmdlineError("missing argument to %s", argv[i]);
        g.fDebug = strtol(argv[++i], 0, 0);
      }else
      if( strcmp(z,"help")==0 ){
        showHelp();
        return 0;
      }else
      if( strcmp(z,"like")==0 ){
        if( i==argc-1 ) cmdlineError("missing argument to %s", argv[i]);
        if( zLike!=0 ) cmdlineError("only one --like allowed");
        zLike = argv[++i];
      }else
      if( strcmp(z,"schema-only")==0 ){
        omitContent = 1;
      }else
      if( strcmp(z,"without-schema")==0 ){
        omitSchema = 1;
      }else
      {
        cmdlineError("unknown option: %s", argv[i]);
      }


    }else{
      nFile++;
      if( nFile<i ) argv[nFile] = argv[i];
    }
  }
  if( nFile==0 ){
    cmdlineError("no input files specified - nothing to do");
  }
  if( omitSchema && omitContent ){
    cmdlineError("only one of --without-schema and --omit-schema allowed");
  }
  if( zLike==0 ) zLike = "%";

  for(i=1; i<=nFile; i++){
    static const int openFlags = 
       SQLITE_OPEN_READWRITE |     /* Read/write so hot journals can recover */
       SQLITE_OPEN_URI
    ;
    zDb = argv[i];
    rc = sqlite3_open_v2(zDb, &g.db, openFlags, 0);
    if( rc ){
      fprintf(stderr, "cannot open database file '%s'\n", zDb);
      continue;
    }
    rc = sqlite3_exec(g.db, "SELECT * FROM sqlite_master", 0, 0, &zErrMsg);
    if( rc || zErrMsg ){
      sqlite3_close(g.db);
      g.db = 0;
      fprintf(stderr, "'%s' is not a valid SQLite database\n", zDb);
      continue;
    }

    /* Start the hash */
    hash_init();
  
    /* Hash table content */
    if( !omitContent ){
      pStmt = db_prepare(
        "SELECT name FROM sqlite_master\n"
        " WHERE type='table' AND sql NOT LIKE 'CREATE VIRTUAL%%'\n"
        "   AND name NOT LIKE 'sqlite_%%'\n"
        "   AND name LIKE '%q'\n"
        " ORDER BY name COLLATE nocase;\n",
        zLike
      );

      while( SQLITE_ROW==sqlite3_step(pStmt) ){
        /* We want rows of the table to be hashed in PRIMARY KEY order.
        ** Technically, an ORDER BY clause is required to guarantee that
        ** order.  However, though not guaranteed by the documentation, every
        ** historical version of SQLite has always output rows in PRIMARY KEY
        ** order when there is no WHERE or GROUP BY clause, so the ORDER BY
        ** can be safely omitted. */
        hash_one_query("SELECT * FROM \"%w\"", sqlite3_column_text(pStmt,0));
      }
      sqlite3_finalize(pStmt);
    }
  
    /* Hash the database schema */
    if( !omitSchema ){
      hash_one_query(
         "SELECT type, name, tbl_name, sql FROM sqlite_master\n"
         " WHERE tbl_name LIKE '%q'\n"
         " ORDER BY name COLLATE nocase;\n",
         zLike
      );
    }
  
    /* Finish and output the hash and close the database connection. */
    hash_finish(zDb);
    sqlite3_close(g.db);
  }
  return 0;
}