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authorSiddhesh Poyarekar <siddhesh@sourceware.org>2021-07-22 18:37:59 +0530
committerSiddhesh Poyarekar <siddhesh@sourceware.org>2021-07-22 18:37:59 +0530
commit2d2d9f2b48a943fa556301db532103d09800da4d (patch)
tree1adb6efbb63ebadd37233851cf14e5cf394de59f /resolv
parent55a4dd39308951da4b0da84b19e415c2bb451b60 (diff)
downloadglibc-2d2d9f2b48a943fa556301db532103d09800da4d.tar.gz
glibc-2d2d9f2b48a943fa556301db532103d09800da4d.tar.xz
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Move malloc hooks into a compat DSO
Remove all malloc hook uses from core malloc functions and move it
into a new library libc_malloc_debug.so.  With this, the hooks now no
longer have any effect on the core library.

libc_malloc_debug.so is a malloc interposer that needs to be preloaded
to get hooks functionality back so that the debugging features that
depend on the hooks, i.e. malloc-check, mcheck and mtrace work again.
Without the preloaded DSO these debugging features will be nops.
These features will be ported away from hooks in subsequent patches.

Similarly, legacy applications that need hooks functionality need to
preload libc_malloc_debug.so.

The symbols exported by libc_malloc_debug.so are maintained at exactly
the same version as libc.so.

Finally, static binaries will no longer be able to use malloc
debugging features since they cannot preload the debugging DSO.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Diffstat (limited to 'resolv')
-rw-r--r--resolv/Makefile9
1 files changed, 6 insertions, 3 deletions
diff --git a/resolv/Makefile b/resolv/Makefile
index e138a1fdac..59e599535c 100644
--- a/resolv/Makefile
+++ b/resolv/Makefile
@@ -215,19 +215,22 @@ $(objpfx)tst-res_hconf_reorder: $(shared-thread-library)
 tst-res_hconf_reorder-ENV = RESOLV_REORDER=on
 
 $(objpfx)tst-leaks: $(objpfx)libresolv.so
-tst-leaks-ENV = MALLOC_TRACE=$(objpfx)tst-leaks.mtrace
+tst-leaks-ENV = MALLOC_TRACE=$(objpfx)tst-leaks.mtrace \
+		LD_PRELOAD=$(common-objpfx)/malloc/libc_malloc_debug.so
 $(objpfx)mtrace-tst-leaks.out: $(objpfx)tst-leaks.out
 	$(common-objpfx)malloc/mtrace $(objpfx)tst-leaks.mtrace > $@; \
 	$(evaluate-test)
 
-tst-leaks2-ENV = MALLOC_TRACE=$(objpfx)tst-leaks2.mtrace
+tst-leaks2-ENV = MALLOC_TRACE=$(objpfx)tst-leaks2.mtrace \
+		 LD_PRELOAD=$(common-objpfx)/malloc/libc_malloc_debug.so
 $(objpfx)mtrace-tst-leaks2.out: $(objpfx)tst-leaks2.out
 	{ test -r $(objpfx)tst-leaks2.mtrace \
 	|| ( echo "tst-leaks2.mtrace does not exist"; exit 77; ) \
 	&& $(common-objpfx)malloc/mtrace $(objpfx)tst-leaks2.mtrace; } > $@; \
 	$(evaluate-test)
 
-tst-resolv-res_ninit-ENV = MALLOC_TRACE=$(objpfx)tst-resolv-res_ninit.mtrace
+tst-resolv-res_ninit-ENV = MALLOC_TRACE=$(objpfx)tst-resolv-res_ninit.mtrace \
+			LD_PRELOAD=$(common-objpfx)/malloc/libc_malloc_debug.so
 $(objpfx)mtrace-tst-resolv-res_ninit.out: $(objpfx)tst-resolv-res_ninit.out
 	$(common-objpfx)malloc/mtrace \
 	  $(objpfx)tst-resolv-res_ninit.mtrace > $@; \