[PATCH v3 3/3] internally use the symbol __environ instead of environ

[PATCH v3 3/3] internally use the symbol __environ instead of environ

[Jens Gustedt]

When switching optimization to higher levels (-O3) and enable link time
optimization (-flto) my linker explodes because "__environ" is accessed
through an alias named "environ", and that text segment has already been
removed:

`environ' referenced in section `.text.execvp' of /tmp/cckGfCaK.ltrans1.ltrans.o: defined in discarded section `.text' of src/env/__environ.lo (symbol from plugin)
/usr/bin/ld: BFD (GNU Binutils for Ubuntu) 2.22 assertion fail ../../bfd/elf64-x86-64.c:4365

Use the "real" name of __environ directly and make this code consistent
with other functions (such as execv) that already use __environ,
too.

Some places where "environ" is used may already have been silently
renamed through a macro in internal/libc.h, but it is probably better to
have that in the open.

0	1	src/internal/libc.h
2	2	src/process/execvp.c
2	2	src/process/system.c

diff --git a/src/internal/libc.h b/src/internal/libc.h
index 5089114..c9416f0 100644
--- a/src/internal/libc.h
+++ b/src/internal/libc.h
@@ -57,7 +57,6 @@ void __synccall(void (*)(void *), void *);
 int __setxid(int, int, int, int);
 
 extern char **__environ;
-#define environ __environ
 
 #undef weak_alias
 #define weak_alias(old, new) \
diff --git a/src/process/execvp.c b/src/process/execvp.c
index 682680d..0a33e42 100644
--- a/src/process/execvp.c
+++ b/src/process/execvp.c
@@ -4,7 +4,7 @@
 #include <errno.h>
 #include <limits.h>
 
-extern char **environ;
+extern char **__environ;
 
 int __execvpe(const char *file, char *const argv[], char *const envp[])
 {
@@ -45,5 +45,5 @@ int __execvpe(const char *file, char *const argv[], char *const envp[])
 
 int execvp(const char *file, char *const argv[])
 {
-	return __execvpe(file, argv, environ);
+	return __execvpe(file, argv, __environ);
 }
diff --git a/src/process/system.c b/src/process/system.c
index 0aa34cd..4232bef 100644
--- a/src/process/system.c
+++ b/src/process/system.c
@@ -13,7 +13,7 @@ static void dummy_0()
 weak_alias(dummy_0, __acquire_ptc);
 weak_alias(dummy_0, __release_ptc);
 
-extern char **environ;
+extern char **__environ;
 
 int system(const char *cmd)
 {
@@ -40,7 +40,7 @@ int system(const char *cmd)
 	posix_spawnattr_setsigdefault(&attr, &reset);
 	posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETSIGDEF|POSIX_SPAWN_SETSIGMASK);
 	ret = posix_spawn(&pid, "/bin/sh", 0, &attr,
-		(char *[]){"sh", "-c", (char *)cmd, 0}, environ);
+		(char *[]){"sh", "-c", (char *)cmd, 0}, __environ);
 	posix_spawnattr_destroy(&attr);
 
 	if (!ret) while (waitpid(pid, &status, 0)<0 && errno == EINTR);
-- 
1.7.9.5

Re: [PATCH v3 3/3] internally use the symbol __environ instead of environ

[Rich Felker]

On Mon, Feb 11, 2013 at 11:51:52PM +0100, Jens Gustedt wrote:
> When switching optimization to higher levels (-O3) and enable link time
> optimization (-flto) my linker explodes because "__environ" is accessed
> through an alias named "environ", and that text segment has already been
> removed:
> 
> `environ' referenced in section `.text.execvp' of /tmp/cckGfCaK.ltrans1.ltrans.o: defined in discarded section `.text' of src/env/__environ.lo (symbol from plugin)
> /usr/bin/ld: BFD (GNU Binutils for Ubuntu) 2.22 assertion fail ../../bfd/elf64-x86-64.c:4365
> 
> Use the "real" name of __environ directly and make this code consistent
> with other functions (such as execv) that already use __environ,
> too.
> 
> Some places where "environ" is used may already have been silently
> renamed through a macro in internal/libc.h, but it is probably better to
> have that in the open.

Committed.

I believe the fix is complete, since the following no longer turns up
any references:

$ grep -r [^_]environ src
src/process/execve.c:   /* do we need to use environ if envp is null? */
src/ldso/dynlink.c:     /* Find aux vector just past environ[] */
src/thread/powerpc/syscall_cp.s:#r31: local or environment pointer
src/env/__environ.c:weak_alias(__environ, environ);

Thanks.

Rich