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elf: Merge __dl_libc_freemem into __rtld_libc_freeres

Browse source 
The functions serve very similar purposes.  The advantage of
__rtld_libc_freeres is that it is located within ld.so, so it is
more natural to poke at link map internals there.

This slightly regresses cleanup capabilities for statically linked
binaries.  If that becomes a problem, we should start calling
__rtld_libc_freeres from __libc_freeres (perhaps after renaming it).
This commit is contained in:
Florian Weimer 2025-02-02 20:10:09 +01:00
parent 749310c61b
commit d12cb8e452
4 changed files with 101 additions and 110 deletions
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107
elf/dl-libc.c
View file

@ -226,110 +226,3 @@ __libc_dlclose (void *map)
#endif
return dlerror_run (do_dlclose, map);
}
static bool
free_slotinfo (struct dtv_slotinfo_list **elemp)
{
size_t cnt;
if (*elemp == NULL)
/* Nothing here, all is removed (or there never was anything). */
return true;
if (!free_slotinfo (&(*elemp)->next))
/* We cannot free the entry. */
return false;
/* That cleared our next pointer for us. */
for (cnt = 0; cnt < (*elemp)->len; ++cnt)
if ((*elemp)->slotinfo[cnt].map != NULL)
/* Still used. */
return false;
/* We can remove the list element. */
free (*elemp);
*elemp = NULL;
return true;
}
void
__dl_libc_freemem (void)
{
struct link_map *l;
struct r_search_path_elem *d;
/* Remove all search directories. */
d = GL(dl_all_dirs);
while (d != GLRO(dl_init_all_dirs))
{
struct r_search_path_elem *old = d;
d = d->next;
free (old);
}
for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns)
{
for (l = GL(dl_ns)[ns]._ns_loaded; l != NULL; l = l->l_next)
{
struct libname_list *lnp = l->l_libname->next;
l->l_libname->next = NULL;
/* Remove all additional names added to the objects. */
while (lnp != NULL)
{
struct libname_list *old = lnp;
lnp = lnp->next;
if (! old->dont_free)
free (old);
}
/* Free the initfini dependency list. */
if (l->l_free_initfini)
free (l->l_initfini);
l->l_initfini = NULL;
}
if (__builtin_expect (GL(dl_ns)[ns]._ns_global_scope_alloc, 0) != 0
&& (GL(dl_ns)[ns]._ns_main_searchlist->r_nlist
// XXX Check whether we need NS-specific initial_searchlist
== GLRO(dl_initial_searchlist).r_nlist))
{
/* All object dynamically loaded by the program are unloaded. Free
the memory allocated for the global scope variable. */
struct link_map **old = GL(dl_ns)[ns]._ns_main_searchlist->r_list;
/* Put the old map in. */
GL(dl_ns)[ns]._ns_main_searchlist->r_list
// XXX Check whether we need NS-specific initial_searchlist
= GLRO(dl_initial_searchlist).r_list;
/* Signal that the original map is used. */
GL(dl_ns)[ns]._ns_global_scope_alloc = 0;
/* Now free the old map. */
free (old);
}
}
/* Free the memory allocated for the dtv slotinfo array. We can do
this only if all modules which used this memory are unloaded. */
#ifdef SHARED
if (GL(dl_initial_dtv) == NULL)
/* There was no initial TLS setup, it was set up later when
it used the normal malloc. */
free_slotinfo (&GL(dl_tls_dtv_slotinfo_list));
else
#endif
/* The first element of the list does not have to be deallocated.
It was allocated in the dynamic linker (i.e., with a different
malloc), and in the static library it's in .bss space. */
free_slotinfo (&GL(dl_tls_dtv_slotinfo_list)->next);
void *scope_free_list = GL(dl_scope_free_list);
GL(dl_scope_free_list) = NULL;
free (scope_free_list);
}

101
elf/dl-libc_freeres.c
View file

@ -19,8 +19,109 @@
#include <ldsodefs.h>
#include <dl-find_object.h>
static bool
free_slotinfo (struct dtv_slotinfo_list **elemp)
{
size_t cnt;
if (*elemp == NULL)
/* Nothing here, all is removed (or there never was anything). */
return true;
if (!free_slotinfo (&(*elemp)->next))
/* We cannot free the entry. */
return false;
/* That cleared our next pointer for us. */
for (cnt = 0; cnt < (*elemp)->len; ++cnt)
if ((*elemp)->slotinfo[cnt].map != NULL)
/* Still used. */
return false;
/* We can remove the list element. */
free (*elemp);
*elemp = NULL;
return true;
}
void
__rtld_libc_freeres (void)
{
struct link_map *l;
struct r_search_path_elem *d;
/* Remove all search directories. */
d = GL(dl_all_dirs);
while (d != GLRO(dl_init_all_dirs))
{
struct r_search_path_elem *old = d;
d = d->next;
free (old);
}
for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns)
{
for (l = GL(dl_ns)[ns]._ns_loaded; l != NULL; l = l->l_next)
{
struct libname_list *lnp = l->l_libname->next;
l->l_libname->next = NULL;
/* Remove all additional names added to the objects. */
while (lnp != NULL)
{
struct libname_list *old = lnp;
lnp = lnp->next;
if (! old->dont_free)
free (old);
}
/* Free the initfini dependency list. */
if (l->l_free_initfini)
free (l->l_initfini);
l->l_initfini = NULL;
}
if (__builtin_expect (GL(dl_ns)[ns]._ns_global_scope_alloc, 0) != 0
&& (GL(dl_ns)[ns]._ns_main_searchlist->r_nlist
// XXX Check whether we need NS-specific initial_searchlist
== GLRO(dl_initial_searchlist).r_nlist))
{
/* All object dynamically loaded by the program are unloaded. Free
the memory allocated for the global scope variable. */
struct link_map **old = GL(dl_ns)[ns]._ns_main_searchlist->r_list;
/* Put the old map in. */
GL(dl_ns)[ns]._ns_main_searchlist->r_list
// XXX Check whether we need NS-specific initial_searchlist
= GLRO(dl_initial_searchlist).r_list;
/* Signal that the original map is used. */
GL(dl_ns)[ns]._ns_global_scope_alloc = 0;
/* Now free the old map. */
free (old);
}
}
/* Free the memory allocated for the dtv slotinfo array. We can do
this only if all modules which used this memory are unloaded. */
#ifdef SHARED
if (GL(dl_initial_dtv) == NULL)
/* There was no initial TLS setup, it was set up later when
it used the normal malloc. */
free_slotinfo (&GL(dl_tls_dtv_slotinfo_list));
else
#endif
/* The first element of the list does not have to be deallocated.
It was allocated in the dynamic linker (i.e., with a different
malloc), and in the static library it's in .bss space. */
free_slotinfo (&GL(dl_tls_dtv_slotinfo_list)->next);
void *scope_free_list = GL(dl_scope_free_list);
GL(dl_scope_free_list) = NULL;
free (scope_free_list);
_dl_find_object_freeres ();
}

1
include/set-freeres.h
View file

@ -38,7 +38,6 @@
Each free routines must be explicit listed below. */
/* From libc.so. */
extern void __dl_libc_freemem (void) attribute_hidden;
extern void __hdestroy (void) attribute_hidden;
extern void __gconv_cache_freemem (void) attribute_hidden;
extern void __gconv_conf_freemem (void) attribute_hidden;

2
malloc/set-freeres.c
View file

@ -28,7 +28,6 @@
# pragma weak __nss_module_freeres
# pragma weak __nss_action_freeres
# pragma weak __nss_database_freeres
# pragma weak __dl_libc_freemem
# pragma weak __hdestroy
# pragma weak __gconv_cache_freemem
# pragma weak __gconv_conf_freemem
@ -136,7 +135,6 @@ __libc_freeres (void)
_IO_cleanup ();
/* We run the resource freeing after IO cleanup. */
call_function_static_weak (__dl_libc_freemem);
call_function_static_weak (__hdestroy);
call_function_static_weak (__gconv_cache_freemem);
call_function_static_weak (__gconv_conf_freemem);