When resolving relocations while loading a library, the linker used to find
symbols by looking them up in the list of all linked libraries for the current
process, as opposed to following just the library's DT_NEEDED entries. This
can cause a problem where the symbol is picked up from the wrong library.
Signed-off-by: Iliyan Malchev <malchev@google.com>
GDB will try to read l_ld of linkmaps and compare the value to vma of
.dynamic sections from shared objects. Since linker does not assign l_ld,
GDB will complain about and re-compute l_addr from l_ld. And, GDB will get a
wrong value.
Prior to this change, the dynamic loader kept track of opened libraries
either by their base name (i.e., libfoo.so instead of /system/lib/libfoo.so)
when the shared library was loaded through the DT_NEEDED tag in an ELF header,
or by whatever name was passed to dlopen(). This created a number of problems,
among which:
1. dlopen("libfoo.so") and dlopen("/path/to/libfoo.so") would open the same
library twice;
2. dlopen("/path/to/libfoo.so") and then dlopen("libbar.so"), where libbar.so
depends on libfoo.so, would open libfoo.so twice.
This patch makes the dynamic loader keep track of each loaded library by
basename, which resolves the above ambiguity. The patch also enforces
library lookup by base name, which means that it will refuse to load another
library that has the same name.
Thanks for the inspiration Iliyan.
Signed-off-by: Erik Gilling <konkers@android.com>
Cc: Iliyan Malchev <malchev@google.com>
This is needed to properly initialize the C runtime when libc.so
is loaded by the dynamic linker.
Move the temporary TLS setup before the first system call, just
in case something really horrible happens, we won't crash when
trying to write an error code in 'errno'
Remove the broken TLS_SLOT_THREAD_ID setup. First, this slot
should normally receive the address of a pthread_internal_t,
not a kernel thread identifier. Second, it is never used by
the linker anyway.
Also remove an obsolete comment.
Changed it so that when the linker generates error messages, they are
scribbled away into a buffer that dlfcn and friends can read from.
Since the error messages are generetad with snprintf, and snprintf
MAY call malloc during some code paths, we now link against a version
of libc that does not contain malloc/free/realloc/calloc. We then define
malloc and friends in the dynamic loader, and make them abort() if they
are ever called.
Signed-off-by: Dima Zavin <dima@android.com>
