Using non-standard libc

[Alexander Tarasikov]

I think you need to grep for the "environ" symbol. Most likely it's in
the crt library (crt1.o or crti.o). On Linux that would be libgcc
(lgcc) which provides crtbegin.o, should be something similar on
FreeBSD.

On Wed, Jan 4, 2017 at 9:05 PM, Derrick McKee <derrick.mckee at gmail.com> wrote:
> Hi,
>
> I am conducting research into memory safety, and I have developed a custom
> LLVM pass.  I have successfully built libc using my pass.  However, when I
> try to compile a helloworld program using my built libc, I get a whole
> bunch of undefined reference errors:
>
> /path/to/custom/clang -static -nostdlib -L/usr/src/lib/libc -lc
> -I/usr/src/include hello.c
>
> /usr/bin/ld: warning: cannot find entry symbol _start; defaulting to
> 0000000000400160
> /usr/src/lib/libc/libc.a(getenv.o): In function `__clean_env':
> /usr/src/lib/libc/stdlib/getenv.c:(.text+0x168): undefined reference to
> `environ'
> /usr/src/lib/libc/stdlib/getenv.c:(.text+0x171): undefined reference to
> `environ'
> /usr/src/lib/libc/libc.a(getenv.o): In function `getenv':
> /usr/src/lib/libc/stdlib/getenv.c:(.text+0x1f6): undefined reference to
> `environ'
> /usr/src/lib/libc/libc.a(getenv.o): In function `__merge_environ':
> /usr/src/lib/libc/stdlib/getenv.c:(.text+0x42d): undefined reference to
> `environ'
> /usr/src/lib/libc/stdlib/getenv.c:(.text+0x459): undefined reference to
> `environ'
> /usr/src/lib/libc/libc.a(getenv.o):/usr/src/lib/libc/stdlib/getenv.c:(.text+0x524):
> more undefined references to `environ' follow
> /usr/src/lib/libc/libc.a(getprogname.o): In function `getprogname':
> /usr/src/lib/libc/gen/getprogname.c:(.text+0x7): undefined reference to
> `__progname'
> /usr/src/lib/libc/libc.a(auxv.o): In function `init_aux_vector_once':
> /usr/src/lib/libc/gen/auxv.c:(.text+0x27): undefined reference to `environ'
> /usr/src/lib/libc/libc.a(exec.o): In function `execl':
> /usr/src/lib/libc/gen/exec.c:(.text+0x154): undefined reference to `environ'
> /usr/src/lib/libc/libc.a(exec.o): In function `execlp':
> /usr/src/lib/libc/gen/exec.c:(.text+0x484): undefined reference to `environ'
> /usr/src/lib/libc/libc.a(exec.o): In function `execvp':
> /usr/src/lib/libc/gen/exec.c:(.text+0x4e3): undefined reference to `environ'
> /usr/src/lib/libc/libc.a(exec.o): In function `execv':
> /usr/src/lib/libc/gen/exec.c:(.text+0x537): undefined reference to `environ'
> /usr/src/lib/libc/libc.a(exec.o):/usr/src/lib/libc/gen/exec.c:(.text+0x5b7):
> more undefined references to `environ' follow
> clang-4.0: error: linker command failed with exit code 1 (use -v to see
> invocation)
>
> Any idea of what I am missing?  Thanks.
> --
> Derrick McKee
> Ph.D. Student at Purdue University
> --
> Derrick McKee
> Ph.D. Student at Purdue University
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-- 
Regards, Alexander