330 lines
8.2 KiB
C
330 lines
8.2 KiB
C
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/*
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** This program searches an SQLite database file for the lengths and
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** offsets for all TEXT or BLOB entries for a particular column of a
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** particular table. The rowid, size and offset for the column are
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** written to standard output. There are three arguments, which are the
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** name of the database file, the table, and the column.
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*/
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#include "sqlite3.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <string.h>
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typedef unsigned char u8;
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typedef struct GState GState;
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#define ArraySize(X) (sizeof(X)/sizeof(X[0]))
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/*
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** Global state information for this program.
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*/
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struct GState {
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char *zErr; /* Error message text */
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FILE *f; /* Open database file */
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int szPg; /* Page size for the database file */
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int iRoot; /* Root page of the table */
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int iCol; /* Column number for the column */
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int pgno; /* Current page number */
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u8 *aPage; /* Current page content */
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u8 *aStack[20]; /* Page stack */
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int aPgno[20]; /* Page number stack */
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int nStack; /* Depth of stack */
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int bTrace; /* True for tracing output */
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};
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/*
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** Write an error.
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*/
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static void ofstError(GState *p, const char *zFormat, ...){
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va_list ap;
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sqlite3_free(p->zErr);
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va_start(ap, zFormat);
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p->zErr = sqlite3_vmprintf(zFormat, ap);
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va_end(ap);
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}
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/*
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** Write a trace message
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*/
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static void ofstTrace(GState *p, const char *zFormat, ...){
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va_list ap;
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if( p->bTrace ){
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va_start(ap, zFormat);
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vprintf(zFormat, ap);
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va_end(ap);
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}
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}
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/*
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** Find the root page of the table and the column number of the column.
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*/
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static void ofstRootAndColumn(
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GState *p, /* Global state */
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const char *zFile, /* Name of the database file */
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const char *zTable, /* Name of the table */
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const char *zColumn /* Name of the column */
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){
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sqlite3 *db = 0;
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sqlite3_stmt *pStmt = 0;
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char *zSql = 0;
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int rc;
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if( p->zErr ) return;
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rc = sqlite3_open(zFile, &db);
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if( rc ){
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ofstError(p, "cannot open database file \"%s\"", zFile);
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goto rootAndColumn_exit;
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}
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zSql = sqlite3_mprintf("SELECT rootpage FROM sqlite_master WHERE name=%Q",
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zTable);
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rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
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if( rc ) ofstError(p, "%s: [%s]", sqlite3_errmsg(db), zSql);
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sqlite3_free(zSql);
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if( p->zErr ) goto rootAndColumn_exit;
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if( sqlite3_step(pStmt)!=SQLITE_ROW ){
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ofstError(p, "cannot find table [%s]\n", zTable);
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sqlite3_finalize(pStmt);
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goto rootAndColumn_exit;
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}
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p->iRoot = sqlite3_column_int(pStmt , 0);
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sqlite3_finalize(pStmt);
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p->iCol = -1;
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zSql = sqlite3_mprintf("PRAGMA table_info(%Q)", zTable);
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rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
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if( rc ) ofstError(p, "%s: [%s}", sqlite3_errmsg(db), zSql);
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sqlite3_free(zSql);
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if( p->zErr ) goto rootAndColumn_exit;
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while( sqlite3_step(pStmt)==SQLITE_ROW ){
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const char *zCol = sqlite3_column_text(pStmt, 1);
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if( strlen(zCol)==strlen(zColumn)
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&& sqlite3_strnicmp(zCol, zColumn, strlen(zCol))==0
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){
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p->iCol = sqlite3_column_int(pStmt, 0);
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break;
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}
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}
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sqlite3_finalize(pStmt);
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if( p->iCol<0 ){
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ofstError(p, "no such column: %s.%s", zTable, zColumn);
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goto rootAndColumn_exit;
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}
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zSql = sqlite3_mprintf("PRAGMA page_size");
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rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
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if( rc ) ofstError(p, "%s: [%s]", sqlite3_errmsg(db), zSql);
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sqlite3_free(zSql);
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if( p->zErr ) goto rootAndColumn_exit;
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if( sqlite3_step(pStmt)!=SQLITE_ROW ){
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ofstError(p, "cannot find page size");
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}else{
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p->szPg = sqlite3_column_int(pStmt, 0);
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}
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sqlite3_finalize(pStmt);
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rootAndColumn_exit:
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sqlite3_close(db);
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return;
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}
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/*
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** Pop a page from the stack
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*/
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static void ofstPopPage(GState *p){
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if( p->nStack<=0 ) return;
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p->nStack--;
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sqlite3_free(p->aStack[p->nStack]);
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p->pgno = p->aPgno[p->nStack-1];
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p->aPage = p->aStack[p->nStack-1];
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}
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/*
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** Push a new page onto the stack.
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*/
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static void ofstPushPage(GState *p, int pgno){
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u8 *pPage;
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size_t got;
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if( p->zErr ) return;
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if( p->nStack >= ArraySize(p->aStack) ){
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ofstError(p, "page stack overflow");
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return;
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}
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p->aPgno[p->nStack] = pgno;
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p->aStack[p->nStack] = pPage = sqlite3_malloc( p->szPg );
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if( pPage==0 ){
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fprintf(stderr, "out of memory\n");
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exit(1);
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}
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p->nStack++;
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p->aPage = pPage;
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p->pgno = pgno;
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fseek(p->f, (pgno-1)*p->szPg, SEEK_SET);
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got = fread(pPage, 1, p->szPg, p->f);
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if( got!=p->szPg ){
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ofstError(p, "unable to read page %d", pgno);
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ofstPopPage(p);
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}
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}
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/* Read a two-byte integer at the given offset into the current page */
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static int ofst2byte(GState *p, int ofst){
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int x = p->aPage[ofst];
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return (x<<8) + p->aPage[ofst+1];
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}
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/* Read a four-byte integer at the given offset into the current page */
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static int ofst4byte(GState *p, int ofst){
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int x = p->aPage[ofst];
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x = (x<<8) + p->aPage[ofst+1];
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x = (x<<8) + p->aPage[ofst+2];
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x = (x<<8) + p->aPage[ofst+3];
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return x;
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}
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/* Read a variable-length integer. Update the offset */
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static sqlite3_int64 ofstVarint(GState *p, int *pOfst){
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sqlite3_int64 x = 0;
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u8 *a = &p->aPage[*pOfst];
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int n = 0;
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while( n<8 && (a[0] & 0x80)!=0 ){
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x = (x<<7) + (a[0] & 0x7f);
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n++;
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a++;
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}
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if( n==8 ){
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x = (x<<8) + a[0];
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}else{
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x = (x<<7) + a[0];
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}
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*pOfst += (n+1);
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return x;
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}
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/* Return the absolute offset into a file for the given offset
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** into the current page */
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static int ofstInFile(GState *p, int ofst){
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return p->szPg*(p->pgno-1) + ofst;
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}
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/* Return the size (in bytes) of the data corresponding to the
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** given serial code */
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static int ofstSerialSize(int scode){
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if( scode<5 ) return scode;
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if( scode==5 ) return 6;
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if( scode<8 ) return 8;
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if( scode<12 ) return 0;
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return (scode-12)/2;
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}
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/* Forward reference */
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static void ofstWalkPage(GState*, int);
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/* Walk an interior btree page */
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static void ofstWalkInteriorPage(GState *p){
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int nCell;
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int i;
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int ofst;
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int iChild;
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nCell = ofst2byte(p, 3);
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for(i=0; i<nCell; i++){
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ofst = ofst2byte(p, 12+i*2);
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iChild = ofst4byte(p, ofst);
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ofstWalkPage(p, iChild);
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if( p->zErr ) return;
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}
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ofstWalkPage(p, ofst4byte(p, 8));
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}
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/* Walk a leaf btree page */
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static void ofstWalkLeafPage(GState *p){
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int nCell;
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int i;
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int ofst;
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int nPayload;
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sqlite3_int64 rowid;
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int nHdr;
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int j;
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int scode;
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int sz;
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int dataOfst;
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char zMsg[200];
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nCell = ofst2byte(p, 3);
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for(i=0; i<nCell; i++){
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ofst = ofst2byte(p, 8+i*2);
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nPayload = ofstVarint(p, &ofst);
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rowid = ofstVarint(p, &ofst);
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if( nPayload > p->szPg-35 ){
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sqlite3_snprintf(sizeof(zMsg), zMsg,
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"# overflow rowid %lld", rowid);
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printf("%s\n", zMsg);
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continue;
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}
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dataOfst = ofst;
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nHdr = ofstVarint(p, &ofst);
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dataOfst += nHdr;
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for(j=0; j<p->iCol; j++){
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scode = ofstVarint(p, &ofst);
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dataOfst += ofstSerialSize(scode);
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}
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scode = ofstVarint(p, &ofst);
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sz = ofstSerialSize(scode);
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sqlite3_snprintf(sizeof(zMsg), zMsg,
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"rowid %12lld size %5d offset %8d",
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rowid, sz, ofstInFile(p, dataOfst));
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printf("%s\n", zMsg);
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}
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}
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/*
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** Output results from a single page.
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*/
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static void ofstWalkPage(GState *p, int pgno){
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if( p->zErr ) return;
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ofstPushPage(p, pgno);
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if( p->zErr ) return;
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if( p->aPage[0]==5 ){
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ofstWalkInteriorPage(p);
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}else if( p->aPage[0]==13 ){
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ofstWalkLeafPage(p);
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}else{
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ofstError(p, "page %d has a faulty type byte: %d", pgno, p->aPage[0]);
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}
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ofstPopPage(p);
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}
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int main(int argc, char **argv){
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GState g;
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memset(&g, 0, sizeof(g));
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if( argc>2 && strcmp(argv[1],"--trace")==0 ){
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g.bTrace = 1;
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argc--;
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argv++;
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}
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if( argc!=4 ){
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fprintf(stderr, "Usage: %s DATABASE TABLE COLUMN\n", *argv);
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exit(1);
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}
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ofstRootAndColumn(&g, argv[1], argv[2], argv[3]);
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if( g.zErr ){
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fprintf(stderr, "%s\n", g.zErr);
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exit(1);
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}
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ofstTrace(&g, "# szPg = %d\n", g.szPg);
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ofstTrace(&g, "# iRoot = %d\n", g.iRoot);
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ofstTrace(&g, "# iCol = %d\n", g.iCol);
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g.f = fopen(argv[1], "rb");
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if( g.f==0 ){
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fprintf(stderr, "cannot open \"%s\"\n", argv[1]);
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exit(1);
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}
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ofstWalkPage(&g, g.iRoot);
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if( g.zErr ){
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fprintf(stderr, "%s\n", g.zErr);
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exit(1);
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}
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return 0;
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}
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