/ Check-in [dfa22ed4]
Login

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

Overview
Comment:Add command-line utilities "offsets.c" and "extract.c" for use in low-level analyzsis of database files.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1:dfa22ed4387f9526b74d5265503c7c8e9d559903
User & Date: drh 2011-08-09 18:14:36
Context
2011-08-10
01:52
Make the openDirectory routine in os_unix.c overrideable so that it can be turned into a harmless no-op for the chromium sandbox. check-in: 6b236069 user: drh tags: trunk
2011-08-09
18:14
Add command-line utilities "offsets.c" and "extract.c" for use in low-level analyzsis of database files. check-in: dfa22ed4 user: drh tags: trunk
2011-08-08
23:48
In os_unix.c, do not open the directory containing the database file when the database file is opened. Instead, wait until time to fsync() the directory. And do not report an error if the open fails, since some systems (Ex: AIX and a chromium sandbox) are unable to open and fsync directories. check-in: 713b1b7d user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Added tool/extract.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
/*
** Extract a range of bytes from a file.
**
** Usage:
**
**    extract FILENAME OFFSET AMOUNT
**
** The bytes are written to standard output.
*/
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv){
  FILE *f;
  char *zBuf;
  int ofst;
  int n;
  size_t got;

  if( argc!=4 ){
    fprintf(stderr, "Usage: %s FILENAME OFFSET AMOUNT\n", *argv);
    return 1;
  }
  f = fopen(argv[1], "rb");
  if( f==0 ){
    fprintf(stderr, "cannot open \"%s\"\n", argv[1]);
    return 1;
  }
  ofst = atoi(argv[2]);
  n = atoi(argv[3]);
  zBuf = malloc( n );
  if( zBuf==0 ){
    fprintf(stderr, "out of memory\n");
    return 1;
  }
  fseek(f, ofst, SEEK_SET);
  got = fread(zBuf, 1, n, f);
  fclose(f);
  if( got<n ){
    fprintf(stderr, "got only %d of %d bytes\n", got, n);
    return 1;
  }else{
    fwrite(zBuf, 1, n, stdout);
  }
  return 0;
}

Added tool/offsets.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
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
/*
** This program searches an SQLite database file for the lengths and
** offsets for all TEXT or BLOB entries for a particular column of a
** particular table.  The rowid, size and offset for the column are
** written to standard output.  There are three arguments, which are the
** name of the database file, the table, and the column.
*/
#include "sqlite3.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

typedef unsigned char u8;
typedef struct GState GState;

#define ArraySize(X)   (sizeof(X)/sizeof(X[0]))

/*
** Global state information for this program.
*/
struct GState {
  char *zErr;           /* Error message text */
  FILE *f;              /* Open database file */
  int szPg;             /* Page size for the database file */
  int iRoot;            /* Root page of the table */
  int iCol;             /* Column number for the column */
  int pgno;             /* Current page number */
  u8 *aPage;            /* Current page content */
  u8 *aStack[20];       /* Page stack */
  int aPgno[20];        /* Page number stack */
  int nStack;           /* Depth of stack */
  int bTrace;           /* True for tracing output */
};

/*
** Write an error.
*/
static void ofstError(GState *p, const char *zFormat, ...){
  va_list ap;
  sqlite3_free(p->zErr);
  va_start(ap, zFormat);
  p->zErr = sqlite3_vmprintf(zFormat, ap);
  va_end(ap);
}

/*
** Write a trace message
*/
static void ofstTrace(GState *p, const char *zFormat, ...){
  va_list ap;
  if( p->bTrace ){
    va_start(ap, zFormat);
    vprintf(zFormat, ap);
    va_end(ap);
  }
}

/*
** Find the root page of the table and the column number of the column.
*/
static void ofstRootAndColumn(
  GState *p,              /* Global state */
  const char *zFile,      /* Name of the database file */
  const char *zTable,     /* Name of the table */
  const char *zColumn     /* Name of the column */
){
  sqlite3 *db = 0;
  sqlite3_stmt *pStmt = 0;
  char *zSql = 0;
  int rc;
  if( p->zErr ) return;
  rc = sqlite3_open(zFile, &db);
  if( rc ){
    ofstError(p, "cannot open database file \"%s\"", zFile);
    goto rootAndColumn_exit;
  }
  zSql = sqlite3_mprintf("SELECT rootpage FROM sqlite_master WHERE name=%Q",
                         zTable);
  rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
  if( rc ) ofstError(p, "%s: [%s]", sqlite3_errmsg(db), zSql);
  sqlite3_free(zSql);
  if( p->zErr ) goto rootAndColumn_exit;
  if( sqlite3_step(pStmt)!=SQLITE_ROW ){
    ofstError(p, "cannot find table [%s]\n", zTable);
    sqlite3_finalize(pStmt);
    goto rootAndColumn_exit;
  }
  p->iRoot = sqlite3_column_int(pStmt , 0);
  sqlite3_finalize(pStmt);

  p->iCol = -1;
  zSql = sqlite3_mprintf("PRAGMA table_info(%Q)", zTable);
  rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
  if( rc ) ofstError(p, "%s: [%s}", sqlite3_errmsg(db), zSql);
  sqlite3_free(zSql);
  if( p->zErr ) goto rootAndColumn_exit;
  while( sqlite3_step(pStmt)==SQLITE_ROW ){
    const char *zCol = sqlite3_column_text(pStmt, 1);
    if( strlen(zCol)==strlen(zColumn)
     && sqlite3_strnicmp(zCol, zColumn, strlen(zCol))==0
    ){
      p->iCol = sqlite3_column_int(pStmt, 0);
      break;
    }
  }
  sqlite3_finalize(pStmt);
  if( p->iCol<0 ){
    ofstError(p, "no such column: %s.%s", zTable, zColumn);
    goto rootAndColumn_exit;
  }

  zSql = sqlite3_mprintf("PRAGMA page_size");
  rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
  if( rc )  ofstError(p, "%s: [%s]", sqlite3_errmsg(db), zSql);
  sqlite3_free(zSql);
  if( p->zErr ) goto rootAndColumn_exit;
  if( sqlite3_step(pStmt)!=SQLITE_ROW ){
    ofstError(p, "cannot find page size");
  }else{
    p->szPg = sqlite3_column_int(pStmt, 0);
  }
  sqlite3_finalize(pStmt);

rootAndColumn_exit:
  sqlite3_close(db);
  return;
}

/*
** Pop a page from the stack
*/
static void ofstPopPage(GState *p){
  if( p->nStack<=0 ) return;
  p->nStack--;
  sqlite3_free(p->aStack[p->nStack]);
  p->pgno = p->aPgno[p->nStack-1];
  p->aPage = p->aStack[p->nStack-1];
}


/*
** Push a new page onto the stack.
*/
static void ofstPushPage(GState *p, int pgno){
  u8 *pPage;
  size_t got;
  if( p->zErr ) return;
  if( p->nStack >= ArraySize(p->aStack) ){
    ofstError(p, "page stack overflow");
    return;
  }
  p->aPgno[p->nStack] = pgno;
  p->aStack[p->nStack] = pPage = sqlite3_malloc( p->szPg );
  if( pPage==0 ){
    fprintf(stderr, "out of memory\n");
    exit(1);
  }
  p->nStack++;
  p->aPage = pPage;
  p->pgno = pgno;
  fseek(p->f, (pgno-1)*p->szPg, SEEK_SET);
  got = fread(pPage, 1, p->szPg, p->f);
  if( got!=p->szPg ){
    ofstError(p, "unable to read page %d", pgno);
    ofstPopPage(p);
  }
}

/* Read a two-byte integer at the given offset into the current page */
static int ofst2byte(GState *p, int ofst){
  int x = p->aPage[ofst];
  return (x<<8) + p->aPage[ofst+1];
}

/* Read a four-byte integer at the given offset into the current page */
static int ofst4byte(GState *p, int ofst){
  int x = p->aPage[ofst];
  x = (x<<8) + p->aPage[ofst+1];
  x = (x<<8) + p->aPage[ofst+2];
  x = (x<<8) + p->aPage[ofst+3];
  return x;
}

/* Read a variable-length integer.  Update the offset */
static sqlite3_int64 ofstVarint(GState *p, int *pOfst){
  sqlite3_int64 x = 0;
  u8 *a = &p->aPage[*pOfst];
  int n = 0;
  while( n<8 && (a[0] & 0x80)!=0 ){
    x = (x<<7) + (a[0] & 0x7f);
    n++;
    a++;
  }
  if( n==8 ){
    x = (x<<8) + a[0];
  }else{
    x = (x<<7) + a[0];
  }
  *pOfst += (n+1);
  return x;
}

/* Return the absolute offset into a file for the given offset
** into the current page */
static int ofstInFile(GState *p, int ofst){
  return p->szPg*(p->pgno-1) + ofst;
}

/* Return the size (in bytes) of the data corresponding to the
** given serial code */
static int ofstSerialSize(int scode){
  if( scode<5 ) return scode;
  if( scode==5 ) return 6;
  if( scode<8 ) return 8;
  if( scode<12 ) return 0;
  return (scode-12)/2;
}

/* Forward reference */
static void ofstWalkPage(GState*, int);

/* Walk an interior btree page */
static void ofstWalkInteriorPage(GState *p){
  int nCell;
  int i;
  int ofst;
  int iChild;

  nCell = ofst2byte(p, 3);
  for(i=0; i<nCell; i++){
    ofst = ofst2byte(p, 12+i*2);
    iChild = ofst4byte(p, ofst);
    ofstWalkPage(p, iChild);
    if( p->zErr ) return;
  }
  ofstWalkPage(p, ofst4byte(p, 8));
}

/* Walk a leaf btree page */
static void ofstWalkLeafPage(GState *p){
  int nCell;
  int i;
  int ofst;
  int nPayload;
  sqlite3_int64 rowid;
  int nHdr;
  int j;
  int scode;
  int sz;
  int dataOfst;
  char zMsg[200];

  nCell = ofst2byte(p, 3);
  for(i=0; i<nCell; i++){
    ofst = ofst2byte(p, 8+i*2);
    nPayload = ofstVarint(p, &ofst);
    rowid = ofstVarint(p, &ofst);
    if( nPayload > p->szPg-35 ){
      sqlite3_snprintf(sizeof(zMsg), zMsg,
         "# overflow rowid %lld", rowid);
      printf("%s\n", zMsg);
      continue;
    }
    dataOfst = ofst;
    nHdr = ofstVarint(p, &ofst);
    dataOfst += nHdr;
    for(j=0; j<p->iCol; j++){
      scode = ofstVarint(p, &ofst);
      dataOfst += ofstSerialSize(scode);
    }
    scode = ofstVarint(p, &ofst);
    sz = ofstSerialSize(scode);
    sqlite3_snprintf(sizeof(zMsg), zMsg,
         "rowid %12lld size %5d offset %8d",
          rowid, sz, ofstInFile(p, dataOfst));
    printf("%s\n", zMsg);
  }
}

/*
** Output results from a single page.
*/
static void ofstWalkPage(GState *p, int pgno){
  if( p->zErr ) return;
  ofstPushPage(p, pgno);
  if( p->zErr ) return;
  if( p->aPage[0]==5 ){
    ofstWalkInteriorPage(p);
  }else if( p->aPage[0]==13 ){
    ofstWalkLeafPage(p);
  }else{
    ofstError(p, "page %d has a faulty type byte: %d", pgno, p->aPage[0]);
  }
  ofstPopPage(p);
}

int main(int argc, char **argv){
  GState g;
  memset(&g, 0, sizeof(g));
  if( argc>2 && strcmp(argv[1],"--trace")==0 ){
    g.bTrace = 1;
    argc--;
    argv++;
  }
  if( argc!=4 ){
    fprintf(stderr, "Usage: %s DATABASE TABLE COLUMN\n", *argv);
    exit(1);
  }
  ofstRootAndColumn(&g, argv[1], argv[2], argv[3]);
  if( g.zErr ){
    fprintf(stderr, "%s\n", g.zErr);
    exit(1);
  }
  ofstTrace(&g, "# szPg = %d\n", g.szPg);
  ofstTrace(&g, "# iRoot = %d\n", g.iRoot);
  ofstTrace(&g, "# iCol = %d\n", g.iCol);
  g.f = fopen(argv[1], "rb");
  if( g.f==0 ){
    fprintf(stderr, "cannot open \"%s\"\n", argv[1]);
    exit(1);
  }
  ofstWalkPage(&g, g.iRoot);
  if( g.zErr ){
    fprintf(stderr, "%s\n", g.zErr);
    exit(1);
  }
  return 0; 
}