From 89dc50921c87e2b4a4612188c5a90abebc02b60d Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Tue, 10 Jan 2023 08:24:18 +0100 Subject: [PATCH] tools/nolibc: export environ as a weak symbol on x86_64 The environ is retrieved from the _start code and is easy to store at this moment. Let's declare the variable weak and store the value into it. By not being static it will be visible to all units. By being weak, if some programs already declared it, they will continue to be able to use it. This was tested both with environ inherited from _start and extracted from envp. Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney --- tools/include/nolibc/arch-x86_64.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h index 8d482505c347c..683702a16a610 100644 --- a/tools/include/nolibc/arch-x86_64.h +++ b/tools/include/nolibc/arch-x86_64.h @@ -178,6 +178,8 @@ struct sys_stat_struct { _ret; \ }) +char **environ __attribute__((weak)); + /* startup code */ /* * x86-64 System V ABI mandates: @@ -191,6 +193,7 @@ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void) "pop %rdi\n" // argc (first arg, %rdi) "mov %rsp, %rsi\n" // argv[] (second arg, %rsi) "lea 8(%rsi,%rdi,8),%rdx\n" // then a NULL then envp (third arg, %rdx) + "mov %rdx, environ\n" // save environ "xor %ebp, %ebp\n" // zero the stack frame "and $-16, %rsp\n" // x86 ABI : esp must be 16-byte aligned before call "call main\n" // main() returns the status code, we'll exit with it. -- 2.30.2