path: root/src
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authorRich Felker <>2021-01-30 16:42:26 -0500
committerRich Felker <>2021-01-30 16:42:26 -0500
commit9afed99c224ab33578623744f40d31bee84ec6ba (patch)
tree6a8daab8e1dad8e3605c6d9dfa9f285b9735dadf /src
parentdd5b6384712fb554bb6e291f2bbcdc9ec2f66554 (diff)
fix inconsistent signature of __libc_start_main
commit 7586360badcae6e73f04eb1b8189ce630281c4b2 removed the unused arguments from the definition of __libc_start_main, making it incompatible with the declaration at the point of call, which still passed 6 arguments. calls with mismatched function type have undefined behavior, breaking LTO and any other tooling that checks for function signature mismatch. removing the extra arguments from the point of call (crt1) is not an option for fixing this, since that would be a change in ABI surface between application and libc. adding back the extra arguments requires some care. on archs that pass arguments on the stack or that reserve argument spill space for the callee on the stack, it imposes an ABI requirement on the caller to provide such space. the modern crt1.c entry point provides such space, but originally there was arch-specific asm for the call to __libc_start_main. the last of this asm was removed in commit 6fef8cafbd0f6f185897bc87feb1ff66e2e204e1, and manual review of the code removed and its prior history was performed to check that all archs/variants passed the legacy init/fini/ldso_fini arguments.
Diffstat (limited to 'src')
1 files changed, 2 insertions, 1 deletions
diff --git a/src/env/__libc_start_main.c b/src/env/__libc_start_main.c
index 8fbe5262..c5b277bd 100644
--- a/src/env/__libc_start_main.c
+++ b/src/env/__libc_start_main.c
@@ -69,7 +69,8 @@ weak_alias(libc_start_init, __libc_start_init);
typedef int lsm2_fn(int (*)(int,char **,char **), int, char **);
static lsm2_fn libc_start_main_stage2;
-int __libc_start_main(int (*main)(int,char **,char **), int argc, char **argv)
+int __libc_start_main(int (*main)(int,char **,char **), int argc, char **argv,
+ void (*init_dummy)(), void(*fini_dummy)(), void(*ldso_dummy)())
char **envp = argv+argc+1;