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cea6ffbd06
When we have a weak reference to a symbol defined in an as-needed library, and that library ends up not-needed, gold simply clears the version information in the symbol table, even if the symbol could have been resolved by a needed library later in the link order. This results in a loss of version information, which can cause the program to bind to the wrong version at run time. This patch lets a dynamic definition override an earlier one if the earlier one is from a not-needed library, so that we can retain the version information from the binding to the needed library. In order to do that, the tracking of needed/not-needed had to be moved up to symbol resolution time, instead of during Symbol_table::set_dynsym_indexes(). In cases where we still end up discarding version information, I've added a warning. For the original problem report and discussion, see: https://stackoverflow.com/questions/50751421/undefined-behavior-in-shared-lib-using-libpthread-but-not-having-it-in-elf-as-d gold/ * resolve.cc (Symbol_table::resolve): Rename tobinding to orig_tobinding. Call set_is_needed() for objects that resolve non-weak references. (Symbol_table::should_override): Allow a dynamic definition to override an earlier one in a not-needed library. * symtab.cc (Symbol_table::set_dynsym_indexes): Remove separate processing for as-needed symbols. Add warning when discarding version informatin. * testsuite/Makefile.am (weak_as_needed): New test case. * testsuite/Makefile.in: Regenerate. * testsuite/weak_as_needed.sh: New test script. * testsuite/weak_as_needed_a.c: New source file. * testsuite/weak_as_needed_b.c: New source file. * testsuite/weak_as_needed_b.script: New version script. * testsuite/weak_as_needed_c.c: New source file. * testsuite/weak_as_needed_c.script: New version script.
24 lines
331 B
C
24 lines
331 B
C
#include <stdio.h>
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__asm__ (".symver bar_v1, bar@v1");
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__asm__ (".symver bar_v2, bar@@v2");
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void bar_v1(void);
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void bar_v2(void);
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void baz(void);
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void bar_v1(void)
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{
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printf("weak_as_needed_b: bar_v1\n");
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}
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void bar_v2(void)
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{
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printf("weak_as_needed_b: bar_v2\n");
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}
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void baz(void)
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{
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printf("weak_as_needed_b: baz\n");
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}
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