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2012-02-03include dummied-out dlopen and dlsym functions for static binariesRich Felker1-1/+10
these don't work (or do anything at all) but at least make it possible to static link programs that insist on "having" dynamic loading support...as long as they don't actually need to use it. adding real support for dlopen/dlsym with static linking is going to be significantly more difficult...
2012-01-23fix broken copy relocations from dynamic linker cleanupRich Felker1-1/+4
this issue affected programs which use global variables exported by non-libc libraries.
2012-01-23dynamic linker support for PIE binaries (position-independent main program)Rich Felker1-3/+6
even with this change, PIE will not work yet due to deficiencies in the crt1.o startup code.
2012-01-23cleanup dynamic linker, removing some code duplicationRich Felker1-80/+66
2012-01-20fix dynamic linker not to depend on DYNAMIC ptr in 0th entry of GOTRich Felker1-3/+12
this fixes an issue using gold instead of gnu ld for linking. it also should eliminate the need of the startup code to even load/pass the got address to the dynamic linker. based on patch submitted by sh4rm4 with minor cosmetic changes. further cleanup will follow.
2012-01-17fix char signedness bug in dynlinker hash functionRich Felker1-1/+2
this only affects non-ascii symbol names, which are probably not in use anyway..
2011-10-01dlsym entry point for armRich Felker1-0/+6
2011-10-01dynamic linker entry point for armRich Felker1-0/+14
mildly tested, seems to work
2011-09-18disable dynamic linking/loading code in static libc builds, for nowRich Felker1-0/+2
it does not work, but some configure scripts will falsely detect support then generate programs that crash when they call dlopen.
2011-09-03fix RTLD_NEXT on x86_64Rich Felker1-1/+1
the return address was being truncated to 32 bits, preventing the dlsym code from determining which module contains the calling code.
2011-08-16ldso: move the suid/secure check code closer to env/auxv processingRich Felker1-7/+7
this does not change behavior, but the idea is to avoid letting other code build up between these two points, whereby the environment variables might get used before security it checked.
2011-08-16honor AT_SECURE aux vector flagRich Felker1-2/+2
2011-08-16RTLD_NEXT supportRich Felker4-3/+32
the asm wrapper is needed to get the return address without compiler-specific extensions.
2011-08-16LD_PRELOAD supportRich Felker1-0/+20
2011-07-25when resolving symbols with only weak defs, use first def, not last defRich Felker1-0/+1
2011-07-24fix resolution of weak symbols (hopefully right now) and vdsoRich Felker1-3/+9
2011-07-24load vdso, if present, into the dso listRich Felker1-2/+31
2011-07-24simplify dynamic linker startupRich Felker1-23/+17
instead of creating temp dso objects on the stack and moving them to the heap if dlopen/dlsym are used, use static objects to begin with, and just donate them to malloc if we no longer need them.
2011-07-01fix dlopen UB due to longjmp/volatile rules violationRich Felker1-1/+1
2011-06-30simple rpath support (no token expansion yet) for dynamic linkerRich Felker1-2/+8
2011-06-29textrel support, cheap and uglyRich Felker1-0/+5
2011-06-28reclaim the memory wasted by dynamic linking for use by mallocRich Felker1-0/+39
2011-06-28use load address from elf header if possibleRich Felker1-1/+1
this is mostly useless for shared libs (though it could help for prelink-like purposes); the intended use case is for adding support for calling the dynamic linker directly to run a program, as in: ./libc.so ./a.out foo this usage is not yet supported.
2011-06-28make dynamic linker relocate the main program image last, after all libsRich Felker1-0/+1
prior to this change, copy relocations for initialized pointer variables would not reflect the relocated contents of the pointer.
2011-06-26fix stale pointer issue in dynamic linker with dlopenRich Felker1-0/+1
2011-06-26don't leave the lock held on dlopen failure..Rich Felker1-2/+2
2011-06-26add RTLD_DEFAULT supportRich Felker1-1/+2
2011-06-26in dlopen: don't use null pointerRich Felker1-3/+3
deps can be null if a library has no dependencies (such as libc itself)
2011-06-26fix resolving symbols in objects loaded in RTLD_LOCAL modeRich Felker1-0/+11
basically we temporarily make the library and all its dependencies part of the global namespace but only for the duration of performing relocations, then return them to their former state.
2011-06-26experimental dlopen/dlsym and dynlink changes needed to support themRich Felker1-8/+125
2011-06-26error handling in dynamic linkingRich Felker1-2/+19
some of the code is not yet used, and is in preparation for dlopen which needs to be able to handle failure loading libraries without terminating the program.
2011-06-25fix some symbol resolution issues in dynamic linkerRich Felker1-4/+4
1. search was wrongly beginning with lib itself rather than dso head 2. inconsistent resolution of function pointers for functions in plt
2011-06-25handle library paths better (ignore empty path components, etc.)Rich Felker1-3/+5
2011-06-25fix possible (questionable) strict aliasing violations and ptr arithRich Felker1-3/+3
2011-06-25proper path searching for dynamic linkerRich Felker1-14/+38
first, use $LD_LIBRARY_PATH unless suid. if that fails, read path from /etc/ld-musl-$ARCH.path and fallback to a builtin default.
2011-06-25discard dso descriptors after performing relocationsRich Felker1-0/+12
eventually (once dlopen exists) this behavior will be conditional on dlopen/dlsym not being reachable.
2011-06-25keep track of which dsos have been relocatedRich Felker1-0/+1
2011-06-23prepare support for LD_LIBRARY_PATH (checking suid/sgid safety)Rich Felker1-0/+6
the use of this test will be much stricter than glibc and other typical implementations; the environment will not be honored whatsoever unless the program is confirmed non-suid/sgid by the aux vector the kernel passed in. no fallback to slow syscall-based checking is used if the kernel fails to provide the information; we simply assume the worst (suid) in this case and refuse to honor environment.
2011-06-19make ldso asm more uniform with rest of codebase (no unnecessary suffixes)Rich Felker1-12/+12
2011-06-19x86_64: ensure that dtor pointer passed to app is 0 so it won't be usedRich Felker1-0/+1
leaving it uninitialized caused unpredictable crashes or worse due to calling an indeterminate function pointer.
2011-06-18dynamic linker 64bit fix: hash table entries are always 32bitRich Felker1-2/+2
2011-06-18experimental dynamic linker!Rich Felker3-0/+412
some notes: - library search path is hard coded - x86_64 code is untested and may not work - dlopen/dlsym is not yet implemented - relocations in read-only memory won't work
2011-02-24various changes in preparation for dynamic linking supportRich Felker1-0/+8
prefer using visibility=hidden for __libc internal data, rather than an accessor function, if the compiler has visibility. optimize with -O3 for PIC targets (shared library). without heavy inlining, reloading the GOT register in small functions kills performance. 20-30% size increase for a single libc.so is not a big deal, compared to comparaible size increase in every static binaries. use -Bsymbolic-functions, not -Bsymbolic. global variables are subject to COPY relocations, and thus binding their addresses in the library at link time will cause library functions to read the wrong (original) copies instead of the copies made in the main program's bss section. add entry point, _start, for dynamic linker.
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