[llvm-bugs] [Bug 33635] New: --wrap foo produces dynamic reloc against __real_foo instead of foo

via llvm-bugs llvm-bugs at lists.llvm.org
Wed Jun 28 14:59:05 PDT 2017


https://bugs.llvm.org/show_bug.cgi?id=33635

            Bug ID: 33635
           Summary: --wrap foo produces dynamic reloc against __real_foo
                    instead of foo
           Product: lld
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: ELF
          Assignee: unassignedbugs at nondot.org
          Reporter: roland at hack.frob.com
                CC: llvm-bugs at lists.llvm.org

r306566

        frobland 1119 % head foo.c
        #include <unistd.h>

        ssize_t __wrap_write(int fd, void *buf, size_t len) {
          return __real_write(fd, buf+1, len-1);
        }

        int main(void) {
          write(1, "hello world\n", 12);
          return 0;
        }
        frobland 1120 % gcc -c foo.c
        frobland 1121 % gcc -o foo.good foo.o -Wl,--wrap,write
        frobland 1122 % hack/bin/ld.lld --sysroot=/ --build-id --eh-frame-hdr
-m elf_x86_64 --hash-style=gnu --as-needed -dynamic-linker
/lib64/ld-linux-x86-64.so.2 -z relro -o foo.lld --wrap write
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crti.o
/usr/lib/gcc/x86_64-linux-gnu/4.8/crtbegin.o
-L/usr/lib/gcc/x86_64-linux-gnu/4.8
-L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu
-L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../lib -L/lib/x86_64-linux-gnu
-L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib
-L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../.. foo.o -lgcc --as-needed -lgcc_s
--no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed
/usr/lib/gcc/x86_64-linux-gnu/4.8/crtend.o
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crtn.o
        frobland 1123 % nm -D foo.good foo.lld

        foo.good:
                         w __gmon_start__
                         U __libc_start_main
                         U write

        foo.lld:
                         U __libc_start_main
                         U __real_write
        00000000002010ed T write
        frobland 1124 %

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