The LD_PRELOAD environment variable allows the user to specify a list of
libraries which should be unconditionally loaded before any others. This
makes possible some useful tricks, such as library interposers.
Change-Id: I433d775ab08ef63a5fbe7b21f87a5642954fc32f
The previous implementation of this flag was broken--it behaved identically
to RTLD_DEFAULT. This adds a proper implementation, which examines the address
of the calling function, and uses it to determine which library to use to begin
the symbol search process.
Change-Id: I2ad2b46363f68932af63a3828a22f9c7987eea67
dladdr() is a GNU extension function, which allows the caller to retrieve
symbol information for a specified memory address. It is useful for things
like generating backtrace information at runtime.
Change-Id: I3a1def1a6c9c666d93e1e97b7d260dfa5b9b79a9
This provides a mini-printf implementation that reduces the
size of the dynamic linker by 25 KB, by preventing the drag of
formatting-related routines from the C library.
Also allow traces to be sent to the log, instead of stdout.
NOTE: You now need to modify Android.mk to enable/disable debug
output.
-- fixes b/2432550
-- ba_prelink is used to manage non-prelinked libraries, hence ba_nonprelink is
a more appropriate name for it
Signed-off-by: Iliyan Malchev <malchev@google.com>
Merge commit 'fe62de1ad036a1417df44b7b1a7c65cc79dc7091' into eclair-plus-aosp
* commit 'fe62de1ad036a1417df44b7b1a7c65cc79dc7091':
Add support for R_ARM_REL32 to the dynamic linker.
Merge commit 'ebf3ea006e5367fff93d2491eec24c4b1a633805'
* commit 'ebf3ea006e5367fff93d2491eec24c4b1a633805':
Add support for R_ARM_REL32 to the dynamic linker.
Merge commit '34ea5117dbeba41ae5dfdfb2c2ec8cae23388b66' into eclair-mr2-plus-aosp
* commit '34ea5117dbeba41ae5dfdfb2c2ec8cae23388b66':
Add support for R_ARM_REL32 to the dynamic linker.
Merge commit '83362689f5b1f6393d376d242fe29541b63ead2d'
* commit '83362689f5b1f6393d376d242fe29541b63ead2d':
added and modified linker to support SuperH architecture
Add the BSD sys_signame array.
added and modified bionic code to support SuperH architecture
Merge commit '9e78de3e3c90ec3c2970431d8eae7378fdc0dac6'
* commit '9e78de3e3c90ec3c2970431d8eae7378fdc0dac6':
bionic/linker: make the buddy allocator compute max_order on its own
bionic/linker: change the buddy allocator to take a handle to the managed area
Merge commit '70bba5160f83ecd6251c4539f747ae39e9ed469c' into eclair-mr2-plus-aosp
* commit '70bba5160f83ecd6251c4539f747ae39e9ed469c':
bionic/linker: make the buddy allocator compute max_order on its own
bionic/linker: change the buddy allocator to take a handle to the managed area
Merge commit '763ac28357f604e0e4196e0a7ad5b0f5cdcf274a' into eclair-plus-aosp
* commit '763ac28357f604e0e4196e0a7ad5b0f5cdcf274a':
bionic/linker: make the buddy allocator compute max_order on its own
bionic/linker: change the buddy allocator to take a handle to the managed area
-- rename struct ba_info to struct ba
-- move the static ba descriptor from ba.c to linker.c and rename it ba_prelink
-- ba_init, ba_allocate, ba_free, ba_start_addr, and ba_len all take a pointer
to struct ba
Signed-off-by: Iliyan Malchev <malchev@google.com>
Merge commit '8213d5c3c072b23f5cc1922d232efe7338091d9b' into eclair-mr2-plus-aosp
* commit '8213d5c3c072b23f5cc1922d232efe7338091d9b':
Allow the dynamic linker to relocate references to thumb symbols in NDK libraries.
Merge commit 'ff7b46b87c4d85881d88c2105a94be6c6accb628' into eclair-plus-aosp
* commit 'ff7b46b87c4d85881d88c2105a94be6c6accb628':
Allow the dynamic linker to relocate references to thumb symbols in NDK libraries.
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>
