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Various glibc functions call __stpcpy and __mempcpy for namespace reasons instead of plain stpcpy and mempcpy. But __stpcpy and __mempcpy are macros that call __builtin_stpcpy and __builtin_mempcpy, and unless GCC optimizes the calls, they end up calling the C functions stpcpy and mempcpy. For calls from within shared libc, libc_hidden_builtin_proto ensures that calls to those C functions are in turn mapped to call __GI_stpcpy and __GI_mempcpy. However, for static libc, and for calls from shared libraries other than libc, the ELF symbols stpcpy and mempcpy end up getting called, breaking the ISO C namespace (in the case of stpcpy) or glibc conventions about not relying on the "future library directions" reservations (in the case of mempcpy). This patch fixes this by adding declarations of these functions to include/string.h, under an appropriate condition, with __asm__ used to change the assembler name used for calls (the mempcpy case was previously discussed, and the approach for the fix is as I suggested in <https://sourceware.org/ml/libc-alpha/2013-02/msg00063.html>). Tested for x86_64 with the testsuite; also checked that dcigettext.o (an example previously noted of undesired calls to stpcpy and mempcpy) now calls __stpcpy and __mempcpy instead, as do non-libc shared libraries (__stpcpy and __mempcpy were already exported from shared libc). Disassembly of installed shared libraries isn't easy to compare because of reordered PLT entries resulting from the change in functions called (libnsl, libnss_compat, libnss_dns, libnss_files, libnss_hesiod, libnss_nis, libnss_nisplus, libpthread, librt all have such changes). [BZ #17573] * include/string.h [NOT_IN_libc || !SHARED] (mempcpy): Declare with asm name __mempcpy. [NOT_IN_libc || !SHARED] (stpcpy): Declare with asm name __stpcpy.
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