/ Check-in [bdf2ec77]
Login
SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Initial check-in of the "scrub.exe" utility program prototype. Not yet fully functional. In particular, no scrubbing is done.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | scrub-backup
Files: files | file ages | folders
SHA1: bdf2ec77d1542d4e9b68218f558710a3efc15823
User & Date: drh 2016-05-05 17:15:23
Context
2016-05-05
23:09
Finished implementation compiles, but untested. check-in: aeb88bdf user: drh tags: scrub-backup
17:15
Initial check-in of the "scrub.exe" utility program prototype. Not yet fully functional. In particular, no scrubbing is done. check-in: bdf2ec77 user: drh tags: scrub-backup
11:53
Renumber internal constants in the printf() implemention for a small performance improvement. check-in: 69d11447 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to Makefile.in.

584
585
586
587
588
589
590




591
592
593
594
595
596
597
sqlite3$(TEXE):	$(TOP)/src/shell.c sqlite3.c
	$(LTLINK) $(READLINE_FLAGS) $(SHELL_OPT) -o $@ \
		$(TOP)/src/shell.c sqlite3.c \
		$(LIBREADLINE) $(TLIBS) -rpath "$(libdir)"

sqldiff$(TEXE):	$(TOP)/tool/sqldiff.c sqlite3.c sqlite3.h
	$(LTLINK) -o $@ $(TOP)/tool/sqldiff.c sqlite3.c $(TLIBS)





srcck1$(BEXE):	$(TOP)/tool/srcck1.c
	$(BCC) -o srcck1$(BEXE) $(TOP)/tool/srcck1.c

sourcetest:	srcck1$(BEXE) sqlite3.c
	./srcck1 sqlite3.c








>
>
>
>







584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
sqlite3$(TEXE):	$(TOP)/src/shell.c sqlite3.c
	$(LTLINK) $(READLINE_FLAGS) $(SHELL_OPT) -o $@ \
		$(TOP)/src/shell.c sqlite3.c \
		$(LIBREADLINE) $(TLIBS) -rpath "$(libdir)"

sqldiff$(TEXE):	$(TOP)/tool/sqldiff.c sqlite3.c sqlite3.h
	$(LTLINK) -o $@ $(TOP)/tool/sqldiff.c sqlite3.c $(TLIBS)

scrub$(TEXE):	$(TOP)/ext/misc/scrub.c sqlite3.o
	$(LTLINK) -o $@ -I. -DSCRUB_STANDALONE \
		$(TOP)/ext/misc/scrub.c sqlite3.o $(TLIBS)

srcck1$(BEXE):	$(TOP)/tool/srcck1.c
	$(BCC) -o srcck1$(BEXE) $(TOP)/tool/srcck1.c

sourcetest:	srcck1$(BEXE) sqlite3.c
	./srcck1 sqlite3.c

Changes to Makefile.msc.

1451
1452
1453
1454
1455
1456
1457



1458
1459
1460
1461
1462
1463
1464
	$(LTLINK) $(SHELL_COMPILE_OPTS) $(READLINE_FLAGS) $(TOP)\src\shell.c $(SHELL_CORE_SRC) \
		/link $(SQLITE3EXEPDB) $(LDFLAGS) $(LTLINKOPTS) $(SHELL_LINK_OPTS) $(LTLIBPATHS) $(LIBRESOBJS) $(LIBREADLINE) $(LTLIBS) $(TLIBS)

# <<mark>>
sqldiff.exe:	$(TOP)\tool\sqldiff.c $(SQLITE3C) $(SQLITE3H)
	$(LTLINK) $(NO_WARN) $(TOP)\tool\sqldiff.c $(SQLITE3C) /link $(LDFLAGS) $(LTLINKOPTS)




srcck1.exe:	$(TOP)\tool\srcck1.c
	$(BCC) $(NO_WARN) -Fe$@ $(TOP)\tool\srcck1.c

sourcetest:	srcck1.exe sqlite3.c
	srcck1.exe sqlite3.c

fuzzershell.exe:	$(TOP)\tool\fuzzershell.c $(SQLITE3C) $(SQLITE3H)







>
>
>







1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
	$(LTLINK) $(SHELL_COMPILE_OPTS) $(READLINE_FLAGS) $(TOP)\src\shell.c $(SHELL_CORE_SRC) \
		/link $(SQLITE3EXEPDB) $(LDFLAGS) $(LTLINKOPTS) $(SHELL_LINK_OPTS) $(LTLIBPATHS) $(LIBRESOBJS) $(LIBREADLINE) $(LTLIBS) $(TLIBS)

# <<mark>>
sqldiff.exe:	$(TOP)\tool\sqldiff.c $(SQLITE3C) $(SQLITE3H)
	$(LTLINK) $(NO_WARN) $(TOP)\tool\sqldiff.c $(SQLITE3C) /link $(LDFLAGS) $(LTLINKOPTS)

scrub.exe:	$(TOP)\ext\misc\scrub.c $(SQLITE3C) $(SQLITE3H)
	$(LTLINK) $(NO_WARN) $(TOP)\ext\misc\scrub.c $(SQLITE3C) /link $(LDFLAGS) $(LTLINKOPTS)

srcck1.exe:	$(TOP)\tool\srcck1.c
	$(BCC) $(NO_WARN) -Fe$@ $(TOP)\tool\srcck1.c

sourcetest:	srcck1.exe sqlite3.c
	srcck1.exe sqlite3.c

fuzzershell.exe:	$(TOP)\tool\fuzzershell.c $(SQLITE3C) $(SQLITE3H)

Added ext/misc/scrub.c.





































































































































































































































































































































































































































































































































































































































>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
/*
** 2016-05-05
**
** 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 implements a utility function (and a utility program) that
** makes a copy of an SQLite database while simultaneously zeroing out all
** deleted content.
**
** Normally (when PRAGMA secure_delete=OFF, which is the default) when SQLite
** deletes content, it does not overwrite the deleted content but rather marks
** the region of the file that held that content as being reusable.  This can
** cause deleted content to recoverable from the database file.  This stale
** content is removed by the VACUUM command, but VACUUM can be expensive for
** large databases.  When in PRAGMA secure_delete=ON mode, the deleted content
** is zeroed, but secure_delete=ON has overhead as well.
**
** This utility attempts to make a copy of a complete SQLite database where
** all of the deleted content is zeroed out in the copy, and it attempts to
** do so while being faster than running VACUUM.
**
** Usage:
**
**   int sqlite3_scrub_backup(
**       const char *zSourceFile,   // Source database filename
**       const char *zDestFile,     // Destination database filename
**       char **pzErrMsg            // Write error message here
**   );
**
** Simply call the API above specifying the filename of the source database
** and the name of the backup copy.  The source database must already exist
** and can be in active use. (A read lock is held during the backup.)  The
** destination file should not previously exist.  If the pzErrMsg parameter
** is non-NULL and if an error occurs, then an error message might be written
** into memory obtained from sqlite3_malloc() and *pzErrMsg made to point to
** that error message.  But if the error is an OOM, the error might not be
** reported.  The routine always returns non-zero if there is an error.
**
** If compiled with -DSCRUB_STANDALONE then a main() procedure is added and
** this file becomes a standalone program that can be run as follows:
**
**      ./sqlite3scrub SOURCE DEST
*/
#include "sqlite3.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

typedef struct ScrubState ScrubState;
typedef unsigned char u8;

/* State information for a scrub-and-backup operation */
struct ScrubState {
  const char *zSrcFile;    /* Name of the source file */
  const char *zDestFile;   /* Name of the destination file */
  int rcErr;               /* Error code */
  char *zErr;              /* Error message text */
  sqlite3 *dbSrc;          /* Source database connection */
  sqlite3_file *pSrc;      /* Source file handle */
  sqlite3 *dbDest;         /* Destination database connection */
  sqlite3_file *pDest;     /* Destination file handle */
  unsigned int szPage;     /* Page size */
  unsigned int nPage;      /* Number of pages */
  u8 *page1;               /* Content of page 1 */
};

/* Store an error message */
static void scrubBackupErr(ScrubState *p, const char *zFormat, ...){
  va_list ap;
  sqlite3_free(p->zErr);
  va_start(ap, zFormat);
  p->zErr = sqlite3_vmprintf(zFormat, ap);
  va_end(ap);
  if( p->rcErr==0 ) p->rcErr = SQLITE_ERROR;
}

/* Allocate memory to hold a single page of content */
static u8 *scrubBackupAllocPage(ScrubState *p){
  u8 *pPage;
  if( p->rcErr ) return 0;
  pPage = sqlite3_malloc( p->szPage );
  if( pPage==0 ) p->rcErr = SQLITE_NOMEM;
  return pPage;
}

/* Read a page from the source database into memory.  Use the memory
** provided by pBuf if not NULL or allocate a new page if pBuf==NULL.
*/
static u8 *scrubBackupRead(ScrubState *p, int pgno, u8 *pBuf){
  int rc;
  sqlite3_int64 iOff;
  u8 *pOut = pBuf;
  if( p->rcErr ) return 0;
  if( pOut==0 ){
    pOut = scrubBackupAllocPage(p);
    if( pOut==0 ) return 0;
  }
  iOff = (pgno-1)*(sqlite3_int64)p->szPage;
  rc = p->pSrc->pMethods->xRead(p->pSrc, pOut, p->szPage, iOff);
  if( rc!=SQLITE_OK ){
    if( pBuf==0 ) sqlite3_free(pOut);
    pOut = 0;
    scrubBackupErr(p, "read failed for page %d", pgno);
    p->rcErr = SQLITE_IOERR;
  }
  return pOut;  
}

/* Write a page to the destination database */
static void scrubBackupWrite(ScrubState *p, int pgno, u8 *pData){
  int rc;
  sqlite3_int64 iOff;
  if( p->rcErr ) return;
  iOff = (pgno-1)*(sqlite3_int64)p->szPage;
  rc = p->pDest->pMethods->xWrite(p->pDest, pData, p->szPage, iOff);
  if( rc!=SQLITE_OK ){
    scrubBackupErr(p, "write failed for page %d", pgno);
    p->rcErr = SQLITE_IOERR;
  }
}

/* Prepare a statement against the "db" database. */
static sqlite3_stmt *scrubBackupPrepare(
  ScrubState *p,      /* Backup context */
  sqlite3 *db,        /* Database to prepare against */
  const char *zSql    /* SQL statement */
){
  sqlite3_stmt *pStmt;
  if( p->rcErr ) return 0;
  p->rcErr = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
  if( p->rcErr ){
    scrubBackupErr(p, "SQL error \"%s\" on \"%s\"",
                   sqlite3_errmsg(db), zSql);
    sqlite3_finalize(pStmt);
    return 0;
  }
  return pStmt;
}


/* Open the source database file */
static void scrubBackupOpenSrc(ScrubState *p){
  sqlite3_stmt *pStmt;
  int rc;
  /* Open the source database file */
  p->rcErr = sqlite3_open_v2(p->zSrcFile, &p->dbSrc,
                 SQLITE_OPEN_READONLY |
                 SQLITE_OPEN_URI | SQLITE_OPEN_PRIVATECACHE, 0);
  if( p->rcErr ){
    scrubBackupErr(p, "cannot open source database: %s",
                      sqlite3_errmsg(p->dbSrc));
    return;
  }
  p->rcErr = sqlite3_exec(p->dbSrc, "BEGIN", 0, 0, 0);
  if( p->rcErr ){
    scrubBackupErr(p,
       "cannot start a read transaction on the source database: %s",
       sqlite3_errmsg(p->dbSrc));
    return;
  }
  pStmt = scrubBackupPrepare(p, p->dbSrc, "PRAGMA page_size");
  if( pStmt==0 ) return;
  rc = sqlite3_step(pStmt);
  if( rc==SQLITE_ROW ){
    p->szPage = sqlite3_column_int(pStmt, 0);
  }else{
    scrubBackupErr(p, "unable to determine the page size");
  }
  sqlite3_finalize(pStmt);
  if( p->rcErr ) return;
  pStmt = scrubBackupPrepare(p, p->dbSrc, "PRAGMA page_count");
  if( pStmt==0 ) return;
  rc = sqlite3_step(pStmt);
  if( rc==SQLITE_ROW ){
    p->nPage = sqlite3_column_int(pStmt, 0);
  }else{
    scrubBackupErr(p, "unable to determine the size of the source database");
  }
  sqlite3_finalize(pStmt);
  sqlite3_file_control(p->dbSrc, "main", SQLITE_FCNTL_FILE_POINTER, &p->pSrc);
  if( p->pSrc==0 || p->pSrc->pMethods==0 ){
    scrubBackupErr(p, "cannot get the source file handle");
    p->rcErr = SQLITE_ERROR;
  }
}

/* Create and open the destination file */
static void scrubBackupOpenDest(ScrubState *p){
  sqlite3_stmt *pStmt;
  int rc;
  char *zSql;
  if( p->rcErr ) return;
  p->rcErr = sqlite3_open_v2(p->zDestFile, &p->dbDest,
                 SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
                 SQLITE_OPEN_URI | SQLITE_OPEN_PRIVATECACHE, 0);
  if( p->rcErr ){
    scrubBackupErr(p, "cannot open destination database: %s",
                      sqlite3_errmsg(p->dbDest));
    return;
  }
  zSql = sqlite3_mprintf("PRAGMA page_size(%u);", p->szPage);
  if( zSql==0 ){
    p->rcErr = SQLITE_NOMEM;
    return;
  }
  p->rcErr = sqlite3_exec(p->dbDest, zSql, 0, 0, 0);
  sqlite3_free(zSql);
  if( p->rcErr ){
    scrubBackupErr(p,
       "cannot set the page size on the destination database: %s",
       sqlite3_errmsg(p->dbDest));
    return;
  }
  sqlite3_exec(p->dbDest, "PRAGMA journal_mode=OFF;", 0, 0, 0);
  p->rcErr = sqlite3_exec(p->dbDest, "BEGIN EXCLUSIVE;", 0, 0, 0);
  if( p->rcErr ){
    scrubBackupErr(p,
       "cannot start a write transaction on the destination database: %s",
       sqlite3_errmsg(p->dbDest));
    return;
  }
  pStmt = scrubBackupPrepare(p, p->dbDest, "PRAGMA page_count;");
  if( pStmt==0 ) return;
  rc = sqlite3_step(pStmt);
  if( rc!=SQLITE_ROW ){
    scrubBackupErr(p, "cannot measure the size of the destination");
  }else if( sqlite3_column_int(pStmt, 0)>1 ){
    scrubBackupErr(p, "destination database is not empty - holds %d pages",
                   sqlite3_column_int(pStmt, 0));
  }
  sqlite3_finalize(pStmt);
  sqlite3_file_control(p->dbDest, "main", SQLITE_FCNTL_FILE_POINTER, &p->pDest);
  if( p->pDest==0 || p->pDest->pMethods==0 ){
    scrubBackupErr(p, "cannot get the destination file handle");
    p->rcErr = SQLITE_ERROR;
  }
}

int sqlite3_scrub_backup(
  const char *zSrcFile,    /* Source file */
  const char *zDestFile,   /* Destination file */
  char **pzErr             /* Write error here if non-NULL */
){
  ScrubState s;
  unsigned int i;
  u8 *pBuf = 0;
  u8 *pData;

  memset(&s, 0, sizeof(s));
  s.zSrcFile = zSrcFile;
  s.zDestFile = zDestFile;

  scrubBackupOpenSrc(&s);
  scrubBackupOpenDest(&s);
  pBuf = scrubBackupAllocPage(&s);

  for(i=1; s.rcErr==0 && i<=s.nPage; i++){
    pData = scrubBackupRead(&s, i, pBuf);
    scrubBackupWrite(&s, i, pData);
  }

  /* Close the destination database without closing the transaction. If we
  ** commit, page zero will be overwritten. */
  sqlite3_close(s.dbDest);

  sqlite3_close(s.dbSrc);
  sqlite3_free(s.page1);
  if( pzErr ){
    *pzErr = s.zErr;
  }else{
    sqlite3_free(s.zErr);
  }
  return s.rcErr;
}   

#ifdef SCRUB_STANDALONE
/* The main() routine when this utility is run as a stand-alone program */
int main(int argc, char **argv){
  char *zErr = 0;
  int rc;
  if( argc!=3 ){
    fprintf(stderr,"Usage: %s SOURCE DESTINATION\n", argv[0]);
    exit(1);
  }
  rc = sqlite3_scrub_backup(argv[1], argv[2], &zErr);
  if( rc==SQLITE_NOMEM ){
    fprintf(stderr, "%s: out of memory\n", argv[0]);
    exit(1);
  }
  if( zErr ){
    fprintf(stderr, "%s: %s\n", argv[0], zErr);
    sqlite3_free(zErr);
    exit(1);
  }
  return 0;
}
#endif

Changes to main.mk.

484
485
486
487
488
489
490



491
492
493
494
495
496
497
	$(TCCX) $(READLINE_FLAGS) -o sqlite3$(EXE) $(SHELL_OPT) \
		$(TOP)/src/shell.c libsqlite3.a $(LIBREADLINE) $(TLIBS) $(THREADLIB)

sqldiff$(EXE):	$(TOP)/tool/sqldiff.c sqlite3.c sqlite3.h
	$(TCCX) -o sqldiff$(EXE) -DSQLITE_THREADSAFE=0 \
		$(TOP)/tool/sqldiff.c sqlite3.c $(TLIBS) $(THREADLIB)




srcck1$(EXE):	$(TOP)/tool/srcck1.c
	$(BCC) -o srcck1$(EXE) $(TOP)/tool/srcck1.c

sourcetest:	srcck1$(EXE) sqlite3.c
	./srcck1 sqlite3.c

fuzzershell$(EXE):	$(TOP)/tool/fuzzershell.c sqlite3.c sqlite3.h







>
>
>







484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
	$(TCCX) $(READLINE_FLAGS) -o sqlite3$(EXE) $(SHELL_OPT) \
		$(TOP)/src/shell.c libsqlite3.a $(LIBREADLINE) $(TLIBS) $(THREADLIB)

sqldiff$(EXE):	$(TOP)/tool/sqldiff.c sqlite3.c sqlite3.h
	$(TCCX) -o sqldiff$(EXE) -DSQLITE_THREADSAFE=0 \
		$(TOP)/tool/sqldiff.c sqlite3.c $(TLIBS) $(THREADLIB)

scrub$(EXE):	$(TOP)/ext/misc/scrub.c sqlite3.o
	$(TCC) -I. -DSCRUB_STANDALONE -o scrub$(EXE) $(TOP)/ext/misc/scrub.c sqlite3.o $(THREADLIB)

srcck1$(EXE):	$(TOP)/tool/srcck1.c
	$(BCC) -o srcck1$(EXE) $(TOP)/tool/srcck1.c

sourcetest:	srcck1$(EXE) sqlite3.c
	./srcck1 sqlite3.c

fuzzershell$(EXE):	$(TOP)/tool/fuzzershell.c sqlite3.c sqlite3.h