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Comment:Omit the maximum loop count on the random name chooser in the VACUUM command. Add a comment to explain why this is safe and does not result in an infinite loop. Ticket #1009. (CVS 2122)
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SHA1: 1241086f23a2ef7aef85139817f0c1b90140481d
User & Date: drh 2004-11-20 19:18:56.000
Context
2004-11-20
19:55
Rename source file sqlite.1 as sqlite3.1. Ticket #995. (CVS 2123) (check-in: 297559c6d1 user: drh tags: trunk)
19:18
Omit the maximum loop count on the random name chooser in the VACUUM command. Add a comment to explain why this is safe and does not result in an infinite loop. Ticket #1009. (CVS 2122) (check-in: 1241086f23 user: drh tags: trunk)
19:18
Rig the sqliteMalloc() routine so that we can make it fail multiple times in a row. Modify the malloc.test procedure to make malloc fail in this way and verify that the failures are still handled correctly. (CVS 2121) (check-in: 519bc9d997 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/vacuum.c.
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**
*************************************************************************
** This file contains code used to implement the VACUUM command.
**
** Most of the code in this file may be omitted by defining the
** SQLITE_OMIT_VACUUM macro.
**
** $Id: vacuum.c,v 1.33 2004/10/30 20:23:09 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"

#ifndef SQLITE_OMIT_VACUUM
/*
** Generate a random name of 20 character in length.








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**
*************************************************************************
** This file contains code used to implement the VACUUM command.
**
** Most of the code in this file may be omitted by defining the
** SQLITE_OMIT_VACUUM macro.
**
** $Id: vacuum.c,v 1.34 2004/11/20 19:18:56 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"

#ifndef SQLITE_OMIT_VACUUM
/*
** Generate a random name of 20 character in length.
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*/
int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db){
  int rc = SQLITE_OK;     /* Return code from service routines */
#ifndef SQLITE_OMIT_VACUUM
  const char *zFilename;  /* full pathname of the database file */
  int nFilename;          /* number of characters  in zFilename[] */
  char *zTemp = 0;        /* a temporary file in same directory as zFilename */
  int i;                  /* Loop counter */
  Btree *pMain;           /* The database being vacuumed */
  Btree *pTemp;
  char *zSql = 0;

  if( !db->autoCommit ){
    sqlite3SetString(pzErrMsg, "cannot VACUUM from within a transaction", 
       (char*)0);








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*/
int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db){
  int rc = SQLITE_OK;     /* Return code from service routines */
#ifndef SQLITE_OMIT_VACUUM
  const char *zFilename;  /* full pathname of the database file */
  int nFilename;          /* number of characters  in zFilename[] */
  char *zTemp = 0;        /* a temporary file in same directory as zFilename */

  Btree *pMain;           /* The database being vacuumed */
  Btree *pTemp;
  char *zSql = 0;

  if( !db->autoCommit ){
    sqlite3SetString(pzErrMsg, "cannot VACUUM from within a transaction", 
       (char*)0);
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  nFilename = strlen(zFilename);
  zTemp = sqliteMalloc( nFilename+100 );
  if( zTemp==0 ){
    rc = SQLITE_NOMEM;
    goto end_of_vacuum;
  }
  strcpy(zTemp, zFilename);
  i = 0;








  do {
    zTemp[nFilename] = '-';
    randomName((unsigned char*)&zTemp[nFilename+1]);
  } while( i<10 && sqlite3OsFileExists(zTemp) );

  /* Attach the temporary database as 'vacuum_db'. The synchronous pragma
  ** can be set to 'off' for this file, as it is not recovered if a crash
  ** occurs anyway. The integrity of the database is maintained by a
  ** (possibly synchronous) transaction opened on the main database before
  ** sqlite3BtreeCopyFile() is called.
  **








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  nFilename = strlen(zFilename);
  zTemp = sqliteMalloc( nFilename+100 );
  if( zTemp==0 ){
    rc = SQLITE_NOMEM;
    goto end_of_vacuum;
  }
  strcpy(zTemp, zFilename);

  /* The randomName() procedure in the following loop uses an excellent
  ** source of randomness to generate a name from a space of 1.3e+31 
  ** possibilities.  So unless the directory already contains on the order
  ** of 1.3e+31 files, the probability that the following loop will
  ** run more than once or twice is vanishingly small.  We are certain
  ** enough that this loop will always terminate (and terminate quickly)
  ** that we don't even bother to set a maximum loop count.
  */
  do {
    zTemp[nFilename] = '-';
    randomName((unsigned char*)&zTemp[nFilename+1]);
  } while( sqlite3OsFileExists(zTemp) );

  /* Attach the temporary database as 'vacuum_db'. The synchronous pragma
  ** can be set to 'off' for this file, as it is not recovered if a crash
  ** occurs anyway. The integrity of the database is maintained by a
  ** (possibly synchronous) transaction opened on the main database before
  ** sqlite3BtreeCopyFile() is called.
  **
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