HP-UX Linker and Libraries User's Guide

$ export LD_PRELOAD="./libB.sl"
$ ldd a.out
./libB.sl => ./libB.sl
./libB.sl => ./libB.sl
libA.sl => ./libA.sl
libB.sl => ./libB.sl
libc.2 => /usr/lib/pa20_64/libc.2
libC.sl => ./libC.sl
libD.sl = ./libD.sl
libdl.1 => /usr/lib/pa20_64/libdl.1
a.out --> libD.sl --> libA.sl --> libB.sl --> libC.sl
Case (ii): LD_PRELOAD = "./libD.sl" In 64-bit mode, the symbol resolution order is:
$ export LD_PRELOAD="./libD.sl"
$ ldd a.out
./libD.sl => ./libD.sl
./libD.sl => ./libD.sl
libA.sl => ./libA.sl
libB.sl => ./libB.sl
libc.2 => /usr/lib/pa20_64/libc.2
libC.sl => ./libC.sl
libD.sl => ./libD.sl
libdl.1 => /usr/lib/pa20_64/libdl.1
a.out --> libD.sl --> libA.sl --> libB.sl- -> libC.sl
If the same symbol is defined in libA.sl and libD.sl, the 64-bit linker toolset uses the symbol
defined in libD.sl because this library is loaded and searched before libA.sl when
LD_PRELOAD="./libD.sl".
32-bit Behavior
With LD_PRELOAD unset, in 32-bit mode the dynamic loader forms a load graph as follows:
1. mark B, load B
2. mark A,
3. traverse D, load D
4. load C
5. load A
With this load graph, the symbol resolution order is built in reverse order in 32-bit mode:
a.out --> libA.sl --> libC.sl --> libD.sl --> libB.sl
Case (i): LD_PRELOAD="./libB.sl"
In 32-bit mode, the dependents of a.out are treated as: libB.sl, libA.sl, libB.sl. The
second libB.sl is ignored by the dynamic loader, because it is a duplicate library. So, the
effective dependents of a.out are treated as: libB.sl, libA.sl. The load graph is:
1. mark A, traverse D,load D
2. load C
3. load A
4. load B
The symbol resolution order is:
a.out --> libB.sl--> libA.sl --> libC.sl --> libD.sl
Case (ii): LD_PRELOAD = "./libD.sl" In 32-bit mode, the load graph is:
1. mark B, load B
2. mark A, traverse D, load D
3. load C
4. load A
Creating Shared Libraries 105