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elf: Determine the caller link map in _dl_open

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No functional change expected.

This is in preparation of adding a fast path to dlopen in case
no link map changes are required.
This commit is contained in:
Florian Weimer 2025-02-02 20:10:09 +01:00
parent d12cb8e452
commit edc6842bbc
1 changed files with 19 additions and 28 deletions

47
elf/dl-open.c
View file

@ -49,8 +49,7 @@ struct dl_open_args
{ {
const char *file; const char *file;
int mode; int mode;
/* This is the caller of the dlopen() function. */ struct link_map *caller_map; /* Derived from the caller address. */
const void *caller_dlopen;
struct link_map *map; struct link_map *map;
/* Namespace ID. */ /* Namespace ID. */
Lmid_t nsid; Lmid_t nsid;
@ -499,30 +498,6 @@ dl_open_worker_begin (void *a)
struct dl_open_args *args = a; struct dl_open_args *args = a;
const char *file = args->file; const char *file = args->file;
int mode = args->mode; int mode = args->mode;
struct link_map *call_map = NULL;
/* Determine the caller's map if necessary. This is needed in case
we have a DST, when we don't know the namespace ID we have to put
the new object in, or when the file name has no path in which
case we need to look along the RUNPATH/RPATH of the caller. */
const char *dst = strchr (file, '$');
if (dst != NULL || args->nsid == __LM_ID_CALLER
|| strchr (file, '/') == NULL)
{
const void *caller_dlopen = args->caller_dlopen;
/* We have to find out from which object the caller is calling.
By default we assume this is the main application. */
call_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
struct link_map *l = _dl_find_dso_for_object ((ElfW(Addr)) caller_dlopen);
if (l)
call_map = l;
if (args->nsid == __LM_ID_CALLER)
args->nsid = call_map->l_ns;
}
/* The namespace ID is now known. Keep track of whether libc.so was /* The namespace ID is now known. Keep track of whether libc.so was
already loaded, to determine whether it is necessary to call the already loaded, to determine whether it is necessary to call the
@ -539,7 +514,7 @@ dl_open_worker_begin (void *a)
/* Load the named object. */ /* Load the named object. */
struct link_map *new; struct link_map *new;
args->map = new = _dl_map_object (call_map, file, lt_loaded, 0, args->map = new = _dl_map_object (args->caller_map, file, lt_loaded, 0,
mode | __RTLD_CALLMAP, args->nsid); mode | __RTLD_CALLMAP, args->nsid);
/* If the pointer returned is NULL this means the RTLD_NOLOAD flag is /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
@ -859,7 +834,6 @@ no more namespaces available for dlmopen()"));
struct dl_open_args args; struct dl_open_args args;
args.file = file; args.file = file;
args.mode = mode; args.mode = mode;
args.caller_dlopen = caller_dlopen;
args.map = NULL; args.map = NULL;
args.nsid = nsid; args.nsid = nsid;
/* args.libc_already_loaded is always assigned by dl_open_worker /* args.libc_already_loaded is always assigned by dl_open_worker
@ -868,6 +842,23 @@ no more namespaces available for dlmopen()"));
args.argv = argv; args.argv = argv;
args.env = env; args.env = env;
/* Determine the caller's map if necessary. This is needed when we
don't know the namespace ID in which we have to put the new object,
in case we have a DST, or when the file name has no path in
which case we need to look along the RUNPATH/RPATH of the caller. */
if (nsid == __LM_ID_CALLER || strchr (file, '$') != NULL
|| strchr (file, '/') == NULL)
{
args.caller_map = _dl_find_dso_for_object ((ElfW(Addr)) caller_dlopen);
if (args.caller_map == NULL)
/* By default we assume this is the main application. */
args.caller_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
if (args.nsid == __LM_ID_CALLER)
args.nsid = args.caller_map->l_ns;
}
else
args.caller_map = NULL;
struct dl_exception exception; struct dl_exception exception;
int errcode = _dl_catch_exception (&exception, dl_open_worker, &args); int errcode = _dl_catch_exception (&exception, dl_open_worker, &args);