MySQL Bugs: #27078: Compile error: lib_sql.cc cast from 'THD*' to 'pthread

Bug #27078	Compile error: lib_sql.cc cast from 'THD*' to 'pthread_t' loses precision
Submitted:	13 Mar 2007 11:16	Modified:	18 Jun 2007 2:50
Reporter:	Andy Fiddaman	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Compiling	Severity:	S2 (Serious)
Version:	4.1, 5.0.37	OS:	Any (some 64 bit)
Assigned to:	Joerg Bruehe	CPU Architecture:	Any

Description:
if gcc -DEMBEDDED_LIBRARY -DMYSQL_SERVER  -DDEFAULT_MYSQL_HOME="\"/opt/mysql\""  -DDATADIR="\"/data/mysql/db\""  -DSHAREDIR="\"/opt/mysql/share/mysql\"" -I. -I. -I.. -I../bdb/build_unix  -I../innobase/include -I../innobase/include   -I../include -I../include  -I../sql -I../sql  -I../sql/examples  -I../regex  -I/opt/openssl/include -I/usr/include   -I/opt/GNUreadline/include  -DDBUG_OFF -O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti   -fno-implicit-templates -fno-exceptions -fno-rtti -DHAVE_RWLOCK_T -MT lib_sql.o -MD -MP -MF ".deps/lib_sql.Tpo" -c -o lib_sql.o lib_sql.cc; \
then mv -f ".deps/lib_sql.Tpo" ".deps/lib_sql.Po"; else rm -f ".deps/lib_sql.Tpo"; exit 1; fi
lib_sql.cc: In function 'void* create_embedded_thd(int)':
lib_sql.cc:593: error: cast from 'THD*' to 'pthread_t' loses precision
*** Error code 1
make: Fatal error: Command failed for target `lib_sql.o'

How to repeat:
Compile on Solaris 10 with gcc 4.1.1

# gcc -v
Using built-in specs.
Target: sparcv9-sun-solaris2.10
Configured with: /data/src/build/gcc-4.1.1/configure --prefix=/opt/GNUgcc --enable-languages=c,c++ --disable-nls sparcv9-sun-solaris2.10
Thread model: posix
gcc version 4.1.1

Thank you for the report.

Please provide configure string you use to compile MySQL.

CC=gcc \
CPPFLAGS="-I/opt/GNUreadline/include" \
CFLAGS="-O3 -fno-omit-frame-pointer" \
CXX=gcc \
CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-
rtti" \
LDFLAGS="-static-libgcc -R/opt/openssl/lib -L/opt/GNUreadline/lib -R/opt/GNUread
line/lib" \
./configure \
        --prefix=$DIR \
        --localstatedir=$DATADIR \
        --with-mysqld-user=mysql \
        \
        --enable-thread-safe-client \
        --with-embedded-server \
        --with-berkeley-db \
        --enable-local-infile \
        --enable-assembler \
        \
        --with-federated-storage-engine \
        \
        --with-extra-charsets=complex \
        \
        --with-openssl=/opt/openssl \
        --with-vio \
        \
        --without-docs \
        --without-man \
        --without-bench \
        --without-readline \
        --with-zlib-dir=/usr

Thank you for the report.

I can not repeat it with current BK sources.

In lib_sql.cc:

593:       thd->real_id= (pthread_t) thd;

/usr/include/sys/types.h: typedef uint_t  pthread_t;

THD * thd ...;

So putting a 64bit value into a 32bit type isn't very smart ...

proposed fix:

--- mysql-5.0.37/libmysqld/lib_sql.cc.orig      Mon Mar  5 20:21:22 2007
+++ mysql-5.0.37/libmysqld/lib_sql.cc   Mon Apr  2 00:34:37 2007
@@ -590,7 +590,7 @@
   thd->set_time();
   thd->init_for_queries();
   thd->client_capabilities= client_flag;
-  thd->real_id= (pthread_t) thd;
+  thd->real_id= pthread_self();

   thd->db= NULL;
   thd->db_length= 0;

Set priority=1, showstopper, because it made the build of 4.1.23 fail.

This happens on all platforms where a pointer ("thd") is larger than the platform-specific "pthread_t" type,
in practice: all 64-bit platforms where "pthread_t" is an "int" (32 bit).

I am fixing this in the 4.1.23 release build, it will then be merged up to 5.0.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/28358

ChangeSet@1.2662, 2007-06-07 23:05:18+02:00, joerg@trift2. +1 -0
  Do not use the "thd" pointer to identify a thread in the embedded lib,
  but rather use the "thread_id" counter.
  
  Fixes bug#27078:
  Compile error: lib_sql.cc cast from 'THD*' to 'pthread_t' loses precision

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/28411

ChangeSet@1.2663, 2007-06-08 17:02:48+02:00, joerg@trift2. +1 -0
  Add a cast, needed by some platforms.
  Still part of the fix for bug#27078.

The bug fix is correct (as dicussed on IRC), but I think we need one more change (for safetly)

In item_func.cc::Item_func_release_lock::val_int() we have:

#ifdef EMBEDDED_LIBRARY
    if (ull->locked && pthread_equal(current_thd->real_id,ull->thread))
#else

I think it should be safer if we change the test to:

 if (ull->locked && current_thd->real_id == ull->thread)

Ok to push your fix, if you do the above change;
If not, please inform me why you don't agree with this.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/28646

ChangeSet@1.2664, 2007-06-13 13:33:00+02:00, joerg@trift2. +1 -0
  sql/item_func.cc
      Improved check for thread identity in the "embedded" case,
      provided by Monty.
      
      This finishes the fixes for bug#27078.

Joerg,  OK to push.

I've set Monty's review bit, based on his most recent comment here and the subsequent patch.

Joerg, if it's possible to collapse the three changes into a single changeset, please do; otherwise, no problem to push as three changesets.

Thanks.

Timothy

Pushed into 5.0.44

Pushed into 5.1.20-beta

No changelog entry needed.

Pushed into 4.1.24