util.c

sqlite 嵌入式数据库的源码

/*
** 2001 September 15
**
** 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.
**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
** $Id: util.c,v 1.136 2005/06/06 15:06:39 drh Exp $
*/
#include "sqliteInt.h"
#include <stdarg.h>
#include <ctype.h>

#if SQLITE_MEMDEBUG>2 && defined(__GLIBC__)
#include <execinfo.h>
void print_stack_trace(){
  void *bt[30];
  int i;
  int n = backtrace(bt, 30);

  fprintf(stderr, "STACK: ");
  for(i=0; i<n;i++){
    fprintf(stderr, "%p ", bt[i]);
  }
  fprintf(stderr, "\n");
}
#else
#define print_stack_trace()
#endif

/*
** If malloc() ever fails, this global variable gets set to 1.
** This causes the library to abort and never again function.
*/
int sqlite3_malloc_failed = 0;

/*
** If SQLITE_MEMDEBUG is defined, then use versions of malloc() and
** free() that track memory usage and check for buffer overruns.
*/
#ifdef SQLITE_MEMDEBUG

/*
** For keeping track of the number of mallocs and frees.   This
** is used to check for memory leaks.  The iMallocFail and iMallocReset
** values are used to simulate malloc() failures during testing in 
** order to verify that the library correctly handles an out-of-memory
** condition.
*/
int sqlite3_nMalloc;         /* Number of sqliteMalloc() calls */
int sqlite3_nFree;           /* Number of sqliteFree() calls */
int sqlite3_iMallocFail;     /* Fail sqliteMalloc() after this many calls */
int sqlite3_iMallocReset = -1; /* When iMallocFail reaches 0, set to this */
#if SQLITE_MEMDEBUG>1
static int memcnt = 0;
#endif

/*
** Number of 32-bit guard words.  This should probably be a multiple of
** 2 since on 64-bit machines we want the value returned by sqliteMalloc()
** to be 8-byte aligned.
*/
#define N_GUARD 2

/*
** Allocate new memory and set it to zero.  Return NULL if
** no memory is available.
*/
void *sqlite3Malloc_(int n, int bZero, char *zFile, int line){
  void *p;
  int *pi;
  int i, k;
  if( sqlite3_iMallocFail>=0 ){
    sqlite3_iMallocFail--;
    if( sqlite3_iMallocFail==0 ){
      sqlite3_malloc_failed++;
#if SQLITE_MEMDEBUG>1
      fprintf(stderr,"**** failed to allocate %d bytes at %s:%d\n",
              n, zFile,line);
#endif
      sqlite3_iMallocFail = sqlite3_iMallocReset;
      return 0;
    }
  }
  if( n==0 ) return 0;
  k = (n+sizeof(int)-1)/sizeof(int);
  pi = malloc( (N_GUARD*2+1+k)*sizeof(int));
  if( pi==0 ){
    if( n>0 ) sqlite3_malloc_failed++;
    return 0;
  }
  sqlite3_nMalloc++;
  for(i=0; i<N_GUARD; i++) pi[i] = 0xdead1122;
  pi[N_GUARD] = n;
  for(i=0; i<N_GUARD; i++) pi[k+1+N_GUARD+i] = 0xdead3344;
  p = &pi[N_GUARD+1];
  memset(p, bZero==0, n);
#if SQLITE_MEMDEBUG>1
  print_stack_trace();
  fprintf(stderr,"%06d malloc %d bytes at 0x%x from %s:%d\n",
      ++memcnt, n, (int)p, zFile,line);
#endif
  return p;
}

/*
** This version of malloc is always a real function, never a macro
*/
void *sqlite3MallocX(int n){
  return sqlite3Malloc_(n, 0, __FILE__, __LINE__);
}

/*
** Check to see if the given pointer was obtained from sqliteMalloc()
** and is able to hold at least N bytes.  Raise an exception if this
** is not the case.
**
** This routine is used for testing purposes only.
*/
void sqlite3CheckMemory(void *p, int N){
  int *pi = p;
  int n, i, k;
  pi -= N_GUARD+1;
  for(i=0; i<N_GUARD; i++){
    assert( pi[i]==0xdead1122 );
  }
  n = pi[N_GUARD];
  assert( N>=0 && N<n );
  k = (n+sizeof(int)-1)/sizeof(int);
  for(i=0; i<N_GUARD; i++){
    assert( pi[k+N_GUARD+1+i]==0xdead3344 );
  }
}

/*
** Free memory previously obtained from sqliteMalloc()
*/
void sqlite3Free_(void *p, char *zFile, int line){
  if( p ){
    int *pi, i, k, n;
    pi = p;
    pi -= N_GUARD+1;
    sqlite3_nFree++;
    for(i=0; i<N_GUARD; i++){
      if( pi[i]!=0xdead1122 ){
        fprintf(stderr,"Low-end memory corruption at 0x%x\n", (int)p);
        return;
      }
    }
    n = pi[N_GUARD];
    k = (n+sizeof(int)-1)/sizeof(int);
    for(i=0; i<N_GUARD; i++){
      if( pi[k+N_GUARD+1+i]!=0xdead3344 ){
        fprintf(stderr,"High-end memory corruption at 0x%x\n", (int)p);
        return;
      }
    }
    memset(pi, 0xff, (k+N_GUARD*2+1)*sizeof(int));
#if SQLITE_MEMDEBUG>1
    fprintf(stderr,"%06d free %d bytes at 0x%x from %s:%d\n",
         ++memcnt, n, (int)p, zFile,line);
#endif
    free(pi);
  }
}

/*
** Resize a prior allocation.  If p==0, then this routine
** works just like sqliteMalloc().  If n==0, then this routine
** works just like sqliteFree().
*/
void *sqlite3Realloc_(void *oldP, int n, char *zFile, int line){
  int *oldPi, *pi, i, k, oldN, oldK;
  void *p;
  if( oldP==0 ){
    return sqlite3Malloc_(n,1,zFile,line);
  }
  if( n==0 ){
    sqlite3Free_(oldP,zFile,line);
    return 0;
  }
  oldPi = oldP;
  oldPi -= N_GUARD+1;
  if( oldPi[0]!=0xdead1122 ){
    fprintf(stderr,"Low-end memory corruption in realloc at 0x%x\n", (int)oldP);
    return 0;
  }
  oldN = oldPi[N_GUARD];
  oldK = (oldN+sizeof(int)-1)/sizeof(int);
  for(i=0; i<N_GUARD; i++){
    if( oldPi[oldK+N_GUARD+1+i]!=0xdead3344 ){
      fprintf(stderr,"High-end memory corruption in realloc at 0x%x\n",
              (int)oldP);
      return 0;
    }
  }
  k = (n + sizeof(int) - 1)/sizeof(int);
  pi = malloc( (k+N_GUARD*2+1)*sizeof(int) );
  if( pi==0 ){
    if( n>0 ) sqlite3_malloc_failed++;
    return 0;
  }
  for(i=0; i<N_GUARD; i++) pi[i] = 0xdead1122;
  pi[N_GUARD] = n;
  for(i=0; i<N_GUARD; i++) pi[k+N_GUARD+1+i] = 0xdead3344;
  p = &pi[N_GUARD+1];
  memcpy(p, oldP, n>oldN ? oldN : n);
  if( n>oldN ){
    memset(&((char*)p)[oldN], 0x55, n-oldN);
  }
  memset(oldPi, 0xab, (oldK+N_GUARD+2)*sizeof(int));
  free(oldPi);
#if SQLITE_MEMDEBUG>1
  print_stack_trace();
  fprintf(stderr,"%06d realloc %d to %d bytes at 0x%x to 0x%x at %s:%d\n",
    ++memcnt, oldN, n, (int)oldP, (int)p, zFile, line);
#endif
  return p;
}

/*
** Make a copy of a string in memory obtained from sqliteMalloc()
*/
char *sqlite3StrDup_(const char *z, char *zFile, int line){
  char *zNew;
  if( z==0 ) return 0;
  zNew = sqlite3Malloc_(strlen(z)+1, 0, zFile, line);
  if( zNew ) strcpy(zNew, z);
  return zNew;
}
char *sqlite3StrNDup_(const char *z, int n, char *zFile, int line){
  char *zNew;
  if( z==0 ) return 0;
  zNew = sqlite3Malloc_(n+1, 0, zFile, line);
  if( zNew ){
    memcpy(zNew, z, n);
    zNew[n] = 0;
  }
  return zNew;
}

/*
** A version of sqliteFree that is always a function, not a macro.
*/
void sqlite3FreeX(void *p){
  sqliteFree(p);
}
#endif /* SQLITE_MEMDEBUG */

/*
** The following versions of malloc() and free() are for use in a
** normal build.
*/
#if !defined(SQLITE_MEMDEBUG)

/*
** Allocate new memory and set it to zero.  Return NULL if
** no memory is available.  See also sqliteMallocRaw().
*/
void *sqlite3Malloc(int n){
  void *p;
  if( (p = malloc(n))==0 ){
    if( n>0 ) sqlite3_malloc_failed++;
  }else{
    memset(p, 0, n);
  }
  return p;
}

/*
** Allocate new memory but do not set it to zero.  Return NULL if
** no memory is available.  See also sqliteMalloc().
*/
void *sqlite3MallocRaw(int n){
  void *p;
  if( (p = malloc(n))==0 ){
    if( n>0 ) sqlite3_malloc_failed++;
  }
  return p;
}

/*
** Free memory previously obtained from sqliteMalloc()
*/
void sqlite3FreeX(void *p){
  if( p ){
    free(p);
  }
}

/*
** Resize a prior allocation.  If p==0, then this routine
** works just like sqliteMalloc().  If n==0, then this routine
** works just like sqliteFree().
*/
void *sqlite3Realloc(void *p, int n){
  void *p2;
  if( p==0 ){
    return sqliteMalloc(n);
  }
  if( n==0 ){
    sqliteFree(p);
    return 0;
  }
  p2 = realloc(p, n);
  if( p2==0 ){
    if( n>0 ) sqlite3_malloc_failed++;
  }
  return p2;
}

/*
** Make a copy of a string in memory obtained from sqliteMalloc()
*/
char *sqlite3StrDup(const char *z){
  char *zNew;
  if( z==0 ) return 0;
  zNew = sqliteMallocRaw(strlen(z)+1);
  if( zNew ) strcpy(zNew, z);
  return zNew;
}
char *sqlite3StrNDup(const char *z, int n){
  char *zNew;
  if( z==0 ) return 0;
  zNew = sqliteMallocRaw(n+1);
  if( zNew ){
    memcpy(zNew, z, n);
    zNew[n] = 0;
  }
  return zNew;
}
#endif /* !defined(SQLITE_MEMDEBUG) */

/*
** Create a string from the 2nd and subsequent arguments (up to the
** first NULL argument), store the string in memory obtained from
** sqliteMalloc() and make the pointer indicated by the 1st argument
** point to that string.  The 1st argument must either be NULL or 
** point to memory obtained from sqliteMalloc().
*/
void sqlite3SetString(char **pz, ...){
  va_list ap;
  int nByte;
  const char *z;
  char *zResult;

  if( pz==0 ) return;
  nByte = 1;
  va_start(ap, pz);
  while( (z = va_arg(ap, const char*))!=0 ){
    nByte += strlen(z);
  }
  va_end(ap);
  sqliteFree(*pz);
  *pz = zResult = sqliteMallocRaw( nByte );
  if( zResult==0 ){
    return;
  }
  *zResult = 0;
  va_start(ap, pz);
  while( (z = va_arg(ap, const char*))!=0 ){
    strcpy(zResult, z);
    zResult += strlen(zResult);
  }
  va_end(ap);
#ifdef SQLITE_DEBUG
#if SQLITE_DEBUG>1
  fprintf(stderr,"string at 0x%x is %s\n", (int)*pz, *pz);
#endif
#endif
}

/*
** Set the most recent error code and error string for the sqlite
** handle "db". The error code is set to "err_code".
**
** If it is not NULL, string zFormat specifies the format of the
** error string in the style of the printf functions: The following
** format characters are allowed:
**
**      %s      Insert a string
**      %z      A string that should be freed after use
**      %d      Insert an integer
**      %T      Insert a token
**      %S      Insert the first element of a SrcList
**
** zFormat and any string tokens that follow it are assumed to be
** encoded in UTF-8.
**
** To clear the most recent error for sqlite handle "db", sqlite3Error
** should be called with err_code set to SQLITE_OK and zFormat set
** to NULL.
*/
void sqlite3Error(sqlite3 *db, int err_code, const char *zFormat, ...){
  if( db && (db->pErr || (db->pErr = sqlite3ValueNew())) ){
    db->errCode = err_code;
    if( zFormat ){
      char *z;
      va_list ap;
      va_start(ap, zFormat);
      z = sqlite3VMPrintf(zFormat, ap);
      va_end(ap);
      sqlite3ValueSetStr(db->pErr, -1, z, SQLITE_UTF8, sqlite3FreeX);
    }else{
      sqlite3ValueSetStr(db->pErr, 0, 0, SQLITE_UTF8, SQLITE_STATIC);
    }
  }
}

/*
** Add an error message to pParse->zErrMsg and increment pParse->nErr.
** The following formatting characters are allowed:
**
**      %s      Insert a string
**      %z      A string that should be freed after use
**      %d      Insert an integer
**      %T      Insert a token
**      %S      Insert the first element of a SrcList
**
** This function should be used to report any error that occurs whilst
** compiling an SQL statement (i.e. within sqlite3_prepare()). The
** last thing the sqlite3_prepare() function does is copy the error
** stored by this function into the database handle using sqlite3Error().
** Function sqlite3Error() should be used during statement execution
** (sqlite3_step() etc.).
*/
void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){
  va_list ap;
  pParse->nErr++;
  sqliteFree(pParse->zErrMsg);
  va_start(ap, zFormat);
  pParse->zErrMsg = sqlite3VMPrintf(zFormat, ap);
  va_end(ap);
}

/*
** Convert an SQL-style quoted string into a normal string by removing
** the quote characters.  The conversion is done in-place.  If the
** input does not begin with a quote character, then this routine
** is a no-op.
**
** 2002-Feb-14: This routine is extended to remove MS-Access style
** brackets from around identifers.  For example:  "[a-b-c]" becomes
** "a-b-c".
*/
void sqlite3Dequote(char *z){
  int quote;
  int i, j;
  if( z==0 ) return;
  quote = z[0];
  switch( quote ){
    case '\'':  break;
    case '"':   break;
    case '[':   quote = ']';  break;
    default:    return;
  }
  for(i=1, j=0; z[i]; i++){
    if( z[i]==quote ){
      if( z[i+1]==quote ){
        z[j++] = quote;
        i++;
      }else{
        z[j++] = 0;
        break;
      }
    }else{
      z[j++] = z[i];
    }
  }
}

/* An array to map all upper-case characters into their corresponding
** lower-case character. 
*/