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Implement support for RTLD_NODELETE flag for dlopen() and -z nodelete

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static linker option. Do it by incrementing reference count on the loaded
object and its dependencies.

Reviewed by:	davidxu, kan
This commit is contained in:
Konstantin Belousov 2009-03-30 08:47:28 +00:00
parent dec9af5a2b
commit 2b0b4ee359
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=190543
4 changed files with 22 additions and 4 deletions
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1
include/dlfcn.h
View File

@ -47,6 +47,7 @@
#define RTLD_GLOBAL 0x100 /* Make symbols globally available. */
#define RTLD_LOCAL 0 /* Opposite of RTLD_GLOBAL, and the default. */
#define RTLD_TRACE 0x200 /* Trace loaded objects and exit. */
#define RTLD_NODELETE 0x01000 /* Do not remove members. */
/*
* Request arguments for dlinfo().

22
libexec/rtld-elf/rtld.c
View File

@ -937,6 +937,8 @@ digest_dynamic(Obj_Entry *obj, int early)
/* XXX */;
if (dynp->d_un.d_val & DF_1_BIND_NOW)
obj->bind_now = true;
if (dynp->d_un.d_val & DF_1_NODELETE)
obj->z_nodelete = true;
break;
default:
@ -1422,15 +1424,21 @@ is_exported(const Elf_Sym *def)
static int
load_needed_objects(Obj_Entry *first)
{
Obj_Entry *obj;
Obj_Entry *obj, *obj1;
for (obj = first; obj != NULL; obj = obj->next) {
Needed_Entry *needed;
for (needed = obj->needed; needed != NULL; needed = needed->next) {
needed->obj = load_object(obj->strtab + needed->name, obj);
if (needed->obj == NULL && !ld_tracing)
obj1 = needed->obj = load_object(obj->strtab + needed->name, obj);
if (obj1 == NULL && !ld_tracing)
return -1;
if (obj1 != NULL && obj1->z_nodelete && !obj1->ref_nodel) {
dbg("obj %s nodelete", obj1->path);
init_dag(obj1);
ref_dag(obj1);
obj1->ref_nodel = true;
}
}
}
@ -1976,12 +1984,13 @@ dlopen(const char *name, int mode)
Obj_Entry **old_obj_tail;
Obj_Entry *obj;
Objlist initlist;
int result, lockstate;
int result, lockstate, nodelete;
LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
if (ld_tracing != NULL)
environ = (char **)*get_program_var_addr("environ");
nodelete = mode & RTLD_NODELETE;
objlist_init(&initlist);
@ -2029,6 +2038,11 @@ dlopen(const char *name, int mode)
if (ld_tracing)
goto trace;
}
if (obj != NULL && (nodelete || obj->z_nodelete) && !obj->ref_nodel) {
dbg("obj %s nodelete", obj->path);
ref_dag(obj);
obj->z_nodelete = obj->ref_nodel = true;
}
}
LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,

2
libexec/rtld-elf/rtld.h
View File

@ -217,6 +217,8 @@ typedef struct Struct_Obj_Entry {
bool tls_done : 1; /* Already allocated offset for static TLS */
bool phdr_alloc : 1; /* Phdr is allocated and needs to be freed. */
bool z_origin : 1; /* Process rpath and soname tokens */
bool z_nodelete : 1; /* Do not unload the object and dependencies */
bool ref_nodel : 1; /* refcount increased to prevent dlclose */
struct link_map linkmap; /* for GDB and dlinfo() */
Objlist dldags; /* Object belongs to these dlopened DAGs (%) */

1
sys/sys/elf_common.h
View File

@ -469,6 +469,7 @@ typedef struct {
/* Values for DT_FLAGS_1 */
#define DF_1_BIND_NOW 0x00000001 /* Same as DF_BIND_NOW */
#define DF_1_GLOBAL 0x00000002 /* Set the RTLD_GLOBAL for object */
#define DF_1_NODELETE 0x00000008 /* Set the RTLD_NODELETE for object */
#define DF_1_ORIGIN 0x00000080 /* Process $ORIGIN */
/* Values for n_type. Used in core files. */