sqlite/tool/offsets.c

330 lines
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/*
** 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;
}