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add support for init/finit (constructors and destructors)

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this is mainly in hopes of supporting c++ (not yet possible for other
reasons) but will also help applications/libraries which use (and more
often, abuse) the gcc __attribute__((__constructor__)) feature in "C"
code.

x86_64 and arm versions of the new startup asm are untested and may
have minor problems.
This commit is contained in:
Rich Felker 2012-02-06 14:39:09 -05:00
commit 4ce3cb5cdd
10 changed files with 75 additions and 7 deletions
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19
src/ldso/dynlink.c
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@ -49,6 +49,7 @@ struct dso
ino_t ino;
int global;
int relocated;
int constructed;
struct dso **deps;
char *name;
char buf[];
@ -471,6 +472,20 @@ static size_t find_dyn(Phdr *ph, size_t cnt, size_t stride)
return 0;
}
static void do_init_fini(struct dso *p)
{
size_t dyn[DYN_CNT] = {0};
for (; p; p=p->prev) {
if (p->constructed) return;
decode_vec(p->dynv, dyn, DYN_CNT);
if (dyn[0] & (1<<DT_FINI))
atexit((void (*)(void))(p->base + dyn[DT_FINI]));
if (dyn[0] & (1<<DT_INIT))
((void (*)(void))(p->base + dyn[DT_INIT]))();
p->constructed = 1;
}
}
void *__dynlink(int argc, char **argv)
{
size_t *auxv, aux[AUX_CNT] = {0};
@ -520,6 +535,7 @@ void *__dynlink(int argc, char **argv)
}
app->name = argv[0];
app->global = 1;
app->constructed = 1;
app->dynv = (void *)(app->base + find_dyn(
(void *)aux[AT_PHDR], aux[AT_PHNUM], aux[AT_PHENT]));
decode_dyn(app);
@ -577,6 +593,9 @@ void *__dynlink(int argc, char **argv)
* error. If the dynamic loader (dlopen) will not be used, free
* all memory used by the dynamic linker. */
runtime = 1;
do_init_fini(tail);
if (!rtld_used) {
free_all(head);
free(sys_path);