Re: [sqlite] Out of memory error for SELECT char();

[Yuriy Kaminskiy]

Eduardo Morras wrote:
> On Sat, 8 Mar 2014 14:09:17 -0500
> Richard Hipp  wrote:
>> It isn't really running out of memory
>>
>> The implementation of char() allocates 4 bytes of output buffer for
>> each input character, which is sufficient to hold any valid unicode
>> codepoint. But with zero input characters, that means it tries to
>> allocate a zero-byte output buffer.  sqlite3_malloc() returns NULL
>> when asked to allocate zero bytes, at which point the char()
>> implementation thinks that the malloc() failed and reports the
>> output-of-memory error.
> 
> It's OS dependant. From malloc FreeBSD man page [...]

malloc() behavior wrt 0-byte allocation is OS-dependent.
sqlite3_malloc() is not: it will return NULL on any OS, regardless of malloc()
implementation.

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Re: [sqlite] Out of memory error for SELECT char();

[Eduardo Morras]

On Sat, 8 Mar 2014 14:09:17 -0500
Richard Hipp  wrote:


> It isn't really running out of memory
> 
> The implementation of char() allocates 4 bytes of output buffer for
> each input character, which is sufficient to hold any valid unicode
> codepoint. But with zero input characters, that means it tries to
> allocate a zero-byte output buffer.  sqlite3_malloc() returns NULL
> when asked to allocate zero bytes, at which point the char()
> implementation thinks that the malloc() failed and reports the
> output-of-memory error.

It's OS dependant. From malloc FreeBSD man page, malloc.conf/_malloc_options, V 
option means:

 V   Attempting to allocate zero bytes will return a NULL pointer
 instead of a valid pointer.  (The default behavior is to make a
 minimal allocation and return a pointer to it.)  This option is
 provided for System V compatibility.  This option is incompatible
 with the ``X'' option.

> 
> The fix is to allocate 4*N+1 bytes instead of 4*N bytes.  Dan is
> checking in the fix even as I type this reply.
> 
> 
> -- 
> D. Richard Hipp
> d...@sqlite.org

---   ---
Eduardo Morras 
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Re: [sqlite] Out of memory error for SELECT char();

[Luuk]

On 8-3-2014 19:48, Simon Slavin wrote:


On 8 Mar 2014, at 6:25pm, Zsbán Ambrus  wrote:


In the sqlite3 console, the following very simple statement gives
"Error: out of memory":

SELECT char();

I think this is a bug.


162:~ simon$ sqlite3 ~/Desktop/test.sqlite
SQLite version 3.7.13 2012-07-17 17:46:21
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> SELECT char();
Error: no such function: char
sqlite>

Could you please post your OS and the version of the SQLite shell tool you're 
using ?




It happens on Windows 7 too:

C:\temp>sqlite3
SQLite version 3.8.3.1 2014-02-11 14:52:19
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> select char();
Error: out of memory
sqlite> select char(65);
A
sqlite>

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Re: [sqlite] Out of memory error for SELECT char();

[Richard Hipp]

On Sat, Mar 8, 2014 at 1:25 PM, Zsbán Ambrus  wrote:

> In the sqlite3 console, the following very simple statement gives
> "Error: out of memory":
>
> SELECT char();
>
> I think this is a bug.  This query should need very little memory, so
> it should not give such an error.  I believe it should return a single
> row with a single value of an empty string.
>

It isn't really running out of memory

The implementation of char() allocates 4 bytes of output buffer for each
input character, which is sufficient to hold any valid unicode codepoint.
But with zero input characters, that means it tries to allocate a zero-byte
output buffer.  sqlite3_malloc() returns NULL when asked to allocate zero
bytes, at which point the char() implementation thinks that the malloc()
failed and reports the output-of-memory error.

The fix is to allocate 4*N+1 bytes instead of 4*N bytes.  Dan is checking
in the fix even as I type this reply.


-- 
D. Richard Hipp
d...@sqlite.org
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Re: [sqlite] Out of memory error for SELECT char();

[Dan Kennedy]

On 03/09/2014 01:25 AM, Zsbán Ambrus wrote:

In the sqlite3 console, the following very simple statement gives
"Error: out of memory":

SELECT char();

I think this is a bug.


It is. Thanks for the report. Now fixed here:

  http://www.sqlite.org/src/info/ba39df9d4f

Dan.




   This query should need very little memory, so
it should not give such an error.  I believe it should return a single
row with a single value of an empty string.

I've reproduced this in both a few days old preview
sqlite-amalgamation-201403051440 and the stable sqlite3 3.8.1.

Ambrus
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Re: [sqlite] Out of memory error for SELECT char();

[Zsbán Ambrus]

On 3/8/14, Simon Slavin  wrote:
> SQLite version 3.7.13 2012-07-17 17:46:21

The char function was added in 3.7.16.

> Could you please post your OS and the version of the SQLite shell tool
> you're using ?

I'm using Linux amd64, compiling with gcc 4.8.1.  I've got the out of
memory result in both sqlite 3.8.1 and a few days old preview
sqlite-amalgamation-201403051440.

Ambrus
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Re: [sqlite] Out of memory error for SELECT char();

[Simon Slavin]

On 8 Mar 2014, at 6:25pm, Zsbán Ambrus  wrote:

> In the sqlite3 console, the following very simple statement gives
> "Error: out of memory":
> 
> SELECT char();
> 
> I think this is a bug.

162:~ simon$ sqlite3 ~/Desktop/test.sqlite
SQLite version 3.7.13 2012-07-17 17:46:21
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> SELECT char();
Error: no such function: char
sqlite> 

Could you please post your OS and the version of the SQLite shell tool you're 
using ?

Simon.
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