dlsym() / dladdr() work strange

[Guest One]

I am not sure if it is a real bug or just my improper usage, but attached example works different on Linux and Haiku.

(test.lib.c)

int exoprted_symbol[]= {1, 2, 3, 4, 5, -1};

(test.app.c)

void *ptr;
void *symbol;
Dl_info info;

ptr = dlopen("./test.lib.so", RTLD_LAZY);

if(ptr==NULL)
{
    printf( "%s\n", dlerror() );
    return 1;
}

symbol = dlsym( ptr,  "exoprted_symbol") ;

if ( symbol == NULL )
{
    printf( "%s\n", dlerror() );
    return 1;
}

if( ! dladdr( symbol, &info ) )
{
    printf( "Error mapping address.\n" );
}

printf( "fname=%s\n",  info.dli_fname );
printf( "fbase=%p\n",  info.dli_fbase );
printf( "sname=%s\n",  info.dli_sname );
printf( "saddr=%p\n", info.dli_saddr );

On Linux we have:

fname=./test.lib.so
fbase=0xb78be000
sname=exoprted_symbol
saddr=0xb78c000c

On Haiku:

Error mapping address.
fname=
fbase=0x7ffeef9c
sname=
saddr=(nil)

[axeld]

This looks indeed more like a bug in Haiku, although the code in dladdr() looks pretty much okay.

[Guest One]

I have an idea on this problem, but I won't have a single minute to test it for some time.

Here ( ​http://dev.haiku-os.org/browser/haiku/trunk/src/system/libroot/posix/dlfcn.c?rev=29112 ) we have such condition:

                if (symType == B_SYMBOL_TYPE_TEXT
                    && symLocation <= addr
                    && symLocation >= info->dli_saddr)

If I see things right this means that dladdr() search only for exported functions, not variables, so problem could be solved by:

                if ( (symType == B_SYMBOL_TYPE_TEXT || symType == B_SYMBOL_TYPE_DATA )
                    && symLocation <= addr
                    && symLocation >= info->dli_saddr)

[axeld]

Got rid of the extra check in hrev38373; since dladdr() is a GNU extension, it should better work like it does there.