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Comment:Avoid a left-shift of a negative value (undefined behaviour) when dealing with a corrupt database in fts3. Cherrypick of [b851d12474].
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SHA3-256:2fa63a8be62a06136a34d32351229b54bea58253a63275edf82efe0e83d412ca
User & Date: dan 2018-12-26 11:39:39
Context
2018-12-26
14:23
Fix a problem with corrupt fts3 database detection introduced by [27199380]. Leaf check-in: ceeb4fba user: dan tags: branch-3.22
11:39
Avoid a left-shift of a negative value (undefined behaviour) when dealing with a corrupt database in fts3. Cherrypick of [b851d12474]. check-in: 2fa63a8b user: dan tags: branch-3.22
2018-12-24
13:39
Change the way a comparison used to detect corrupt databases in fts3 is done to avoid potential pointer overflow in 32-bit builds. Cherrypick of [95a9a39ff7]. check-in: 27199380 user: dan tags: branch-3.22
2018-12-22
09:39
Avoid a left-shift of a negative value (undefined behaviour) when dealing with a corrupt database in fts3. check-in: b851d124 user: dan tags: trunk
Changes
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Changes to ext/fts3/fts3.c.

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  }while( vu!=0 );
  q[-1] &= 0x7f;  /* turn off high bit in final byte */
  assert( q - (unsigned char *)p <= FTS3_VARINT_MAX );
  return (int) (q - (unsigned char *)p);
}

#define GETVARINT_STEP(v, ptr, shift, mask1, mask2, var, ret) \
  v = (v & mask1) | ( (*ptr++) << shift );                    \
  if( (v & mask2)==0 ){ var = v; return ret; }
#define GETVARINT_INIT(v, ptr, shift, mask1, mask2, var, ret) \
  v = (*ptr++);                                               \
  if( (v & mask2)==0 ){ var = v; return ret; }

/* 
** Read a 64-bit variable-length integer from memory starting at p[0].
................................................................................
}

/*
** Similar to sqlite3Fts3GetVarint(), except that the output is truncated to 
** a non-negative 32-bit integer before it is returned.
*/
int sqlite3Fts3GetVarint32(const char *p, int *pi){

  u32 a;

#ifndef fts3GetVarint32
  GETVARINT_INIT(a, p, 0,  0x00,     0x80, *pi, 1);
#else
  a = (*p++);
  assert( a & 0x80 );
#endif

  GETVARINT_STEP(a, p, 7,  0x7F,     0x4000, *pi, 2);
  GETVARINT_STEP(a, p, 14, 0x3FFF,   0x200000, *pi, 3);
  GETVARINT_STEP(a, p, 21, 0x1FFFFF, 0x10000000, *pi, 4);
  a = (a & 0x0FFFFFFF );
  *pi = (int)(a | ((u32)(*p & 0x07) << 28));
  assert( 0==(a & 0x80000000) );
  assert( *pi>=0 );
  return 5;
}

/*
** Return the number of bytes required to encode v as a varint







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  }while( vu!=0 );
  q[-1] &= 0x7f;  /* turn off high bit in final byte */
  assert( q - (unsigned char *)p <= FTS3_VARINT_MAX );
  return (int) (q - (unsigned char *)p);
}

#define GETVARINT_STEP(v, ptr, shift, mask1, mask2, var, ret) \
  v = (v & mask1) | ( (*(ptr++)) << shift );  \
  if( (v & mask2)==0 ){ var = v; return ret; }
#define GETVARINT_INIT(v, ptr, shift, mask1, mask2, var, ret) \
  v = (*ptr++);                                               \
  if( (v & mask2)==0 ){ var = v; return ret; }

/* 
** Read a 64-bit variable-length integer from memory starting at p[0].
................................................................................
}

/*
** Similar to sqlite3Fts3GetVarint(), except that the output is truncated to 
** a non-negative 32-bit integer before it is returned.
*/
int sqlite3Fts3GetVarint32(const char *p, int *pi){
  const unsigned char *ptr = (const unsigned char*)p;
  u32 a;

#ifndef fts3GetVarint32
  GETVARINT_INIT(a, ptr, 0,  0x00,     0x80, *pi, 1);
#else
  a = (*ptr++);
  assert( a & 0x80 );
#endif

  GETVARINT_STEP(a, ptr, 7,  0x7F,     0x4000, *pi, 2);
  GETVARINT_STEP(a, ptr, 14, 0x3FFF,   0x200000, *pi, 3);
  GETVARINT_STEP(a, ptr, 21, 0x1FFFFF, 0x10000000, *pi, 4);
  a = (a & 0x0FFFFFFF );
  *pi = (int)(a | ((u32)(*ptr & 0x07) << 28));
  assert( 0==(a & 0x80000000) );
  assert( *pi>=0 );
  return 5;
}

/*
** Return the number of bytes required to encode v as a varint