debug build against non-debug Tcl weird behaviour

[gahr]

So, I nailed down the environment where I can reproduce the failure to this:

./configure --enable-symbols --with-system-lmdb --with-tcl=/usr/local/lib/tcl8.6/

I see this failure:

# cat test.tcl
puts [info patchlevel]
set dir [file dirname [info script]]
load [file join $dir liblmdb0.3.4.so]
package require lmdb

set myenv [lmdb env]
$myenv open -path $dir -mode 0664

# tclsh8.6 test.tcl
8.6.5
ERROR: No such file or directory
    while executing
"$myenv open -path $dir -mode 0664"
    (file "test.tcl" line 7)
root@dev.ptrcrt.ch:~/github/tcl-lmdb # 

Which I nailed down to this snippet.

1371│       for(i=2; i+1<objc; i+=2){
1372│         zArg = Tcl_GetStringFromObj(objv[i], 0);
1373│         if( strcmp(zArg, "-path")==0 ){
1374│             path = Tcl_GetStringFromObj(objv[i+1], 0);
1375│         } else if( strcmp(zArg, "-mode")==0 ){
1376│             if(Tcl_GetIntFromObj(interp, objv[i+1], (int *)&mode) != TCL_OK) {
1377│                 return TCL_ERROR;
1378│             }                                                                                                                                                  
1379├>        }

The for loop is entered twice, the first time to parse the -path "." arguments pair, the second time to parse the -mode 0664 arguments pair.

path is nice until the call at 1376 returns, then it's junk. Here's an extract from my debugging session:

Breakpoint 5, LMDB_ENV (cd=0x0, interp=0x801c30010, objc=6, objv=0x801c632f0) at ./generic/tclmdb.c:1374                                                             
(gdb) next                                                                                                                                                           
(gdb) p path                                                                                                                                                         
$3 = 0x801ce4810 "."                                                                                                                                                 
(gdb) c                                                                                                                                                              
Continuing.                                                                                                                                                          

Breakpoint 6, LMDB_ENV (cd=0x0, interp=0x801c30010, objc=6, objv=0x801c632f0) at ./generic/tclmdb.c:1376                                                             
(gdb) next                                                                                                                                                           
(gdb) p path                                                                                                                                                         
$4 = 0x801ce0000 "\001\b"   

I am not able to explain this yet.

[gahr]

Output from make:

# gmake
cc -DPACKAGE_NAME=\"lmdb\" -DPACKAGE_TARNAME=\"lmdb\" -DPACKAGE_VERSION=\"0.3.4\" -DPACKAGE_STRING=\"lmdb\ 0.3.4\" -DPACKAGE_BUGREPORT=\"\" -DPACKAGE_URL=\"\" -DBUIL
D_lmdb=/\*\*/ -DSTDC_HEADERS=1 -DHAVE_SYS_TYPES_H=1 -DHAVE_SYS_STAT_H=1 -DHAVE_STDLIB_H=1 -DHAVE_STRING_H=1 -DHAVE_MEMORY_H=1 -DHAVE_STRINGS_H=1 -DHAVE_INTTYPES_H=1 
-DHAVE_STDINT_H=1 -DHAVE_UNISTD_H=1 -DNO_VALUES_H=1 -DHAVE_LIMITS_H=1 -DHAVE_SYS_PARAM_H=1 -DHAVE_LMDB_H=1 -DUSE_SYSTEM_LMDB=1 -DUSE_THREAD_ALLOC=1 -D_REENTRANT=1 -D
_THREAD_SAFE=1 -DTCL_THREADS=1 -DMODULE_SCOPE=extern\ __attribute__\(\(__visibility__\(\"hidden\"\)\)\) -DHAVE_HIDDEN=1 -DHAVE_CAST_TO_UNION=1 -DTCL_WIDE_INT_IS_LONG
=1 -DUSE_TCL_STUBS=1  -I"/usr/local/include/tcl8.6"    -I/usr/local/include -O0 -pipe  -g -Wall -fPIC -I/usr/local/include -c `echo ./generic/tclmdb.c` -o tclmdb.o
rm -f liblmdb0.3.4.so
cc -shared -o liblmdb0.3.4.so tclmdb.o -llmdb -Wl,-soname,liblmdb0.3.4.so -L/usr/local/lib -ltclstub86 
: liblmdb0.3.4.so

With

# cc --version
FreeBSD clang version 3.4.1 (tags/RELEASE_34/dot1-final 208032) 20140512
Target: x86_64-unknown-freebsd10.3
Thread model: posix

[gahr]

Same with clang 3.7.1 and clang 3.8.0, gcc-4.8.5 works fine instead.

This is all on FreeBSD 10.3-RELEASE-p2, amd64.

[gahr]

I think I got it. mdb_mode_t is typedef'd to mode_t, which on FreeBSD amd64 is eventually typedef'd to unsigned short - 16 bits. Doing Tcl_GetIntFromObj on it overwrites part of the char * holding the path variable.
The fix would be to change mode to int and cast it to mdb_mode_t only when passing it to mdb_env_open.
I can provide a patch tomorrow.