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Implement dlsym(RTLD_NEXT, symbol).

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This commit is contained in:
John Polstra 1997-08-02 04:56:44 +00:00
parent 8889c700f3
commit 7e7344e2f4
8 changed files with 179 additions and 35 deletions
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76
gnu/usr.bin/ld/rtld/rtld.c
View File

@ -27,7 +27,7 @@
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id$
* $Id: rtld.c,v 1.46 1997/02/22 15:46:48 peter Exp $
*/
#include <sys/param.h>
@ -204,9 +204,10 @@ static int __dlclose __P((void *));
static void *__dlsym __P((void *, char *));
static char *__dlerror __P((void));
static void __dlexit __P((void));
static void *__dlsym3 __P((void *, char *, void *));
static struct ld_entry ld_entry = {
__dlopen, __dlclose, __dlsym, __dlerror, __dlexit
__dlopen, __dlclose, __dlsym, __dlerror, __dlexit, __dlsym3
};
void xprintf __P((char *, ...));
@ -411,7 +412,7 @@ struct _dynamic *dp;
(void)close(crtp->crt_ldfd);
anon_close();
return LDSO_VERSION_HAS_DLEXIT;
return LDSO_VERSION_HAS_DLSYM3;
}
void
@ -1896,26 +1897,77 @@ __dlclose(fd)
return 0;
}
/*
* This form of dlsym is obsolete. Current versions of crt0 don't call
* it. It can still be called by old executables that were linked with
* old versions of crt0.
*/
static void *
__dlsym(fd, sym)
void *fd;
char *sym;
{
struct so_map *smp = (struct so_map *)fd, *src_map = NULL;
if (fd == RTLD_NEXT) {
generror("RTLD_NEXT not supported by this version of"
" /usr/lib/crt0.o");
return NULL;
}
return __dlsym3(fd, sym, NULL);
}
static void *
__dlsym3(fd, sym, retaddr)
void *fd;
char *sym;
void *retaddr;
{
struct so_map *smp;
struct so_map *src_map;
struct nzlist *np;
long addr;
/*
* Restrict search to passed map if dlopen()ed.
*/
if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_DL)
src_map = smp;
if (fd == RTLD_NEXT) {
/* Find the shared object that contains the caller. */
for (smp = link_map_head; smp != NULL; smp = smp->som_next) {
void *textbase = smp->som_addr + LM_TXTADDR(smp);
void *textlimit = LM_ETEXT(smp);
np = lookup(sym, &src_map, 1);
if (np == NULL)
if (textbase <= retaddr && retaddr < textlimit)
break;
}
if (smp == NULL) {
generror("Cannot determine caller's shared object");
return NULL;
}
smp = smp->som_next;
if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_RTLD)
smp = smp->som_next;
if (smp == NULL) {
generror("No next shared object for RTLD_NEXT");
return NULL;
}
do {
src_map = smp;
np = lookup(sym, &src_map, 1);
} while (np == NULL && (smp = smp->som_next) != NULL);
} else {
smp = (struct so_map *)fd;
src_map = NULL;
/*
* Restrict search to passed map if dlopen()ed.
*/
if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_DL)
src_map = smp;
np = lookup(sym, &src_map, 1);
}
if (np == NULL) {
generror("Undefined symbol");
return NULL;
}
/* Fixup jmpslot so future calls transfer directly to target */
addr = np->nz_value;
if (src_map)
addr += (long)src_map->som_addr;

4
include/link.h
View File

@ -27,7 +27,7 @@
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id: link.h,v 1.12 1997/05/07 02:26:34 eivind Exp $
* $Id: link.h,v 1.13 1997/05/07 20:00:00 eivind Exp $
*/
/*
@ -167,6 +167,7 @@ struct so_debug {
*/
#define LDSO_VERSION_NONE 0 /* FreeBSD2.0, 2.0.5 */
#define LDSO_VERSION_HAS_DLEXIT 1 /* includes dlexit in ld_entry */
#define LDSO_VERSION_HAS_DLSYM3 2 /* includes 3-argument dlsym */
/*
* Entry points into ld.so - user interface to the run-time linker.
@ -179,6 +180,7 @@ struct ld_entry {
void *(*dlsym) __P((void *, char *)); /* NONE */
char *(*dlerror) __P((void)); /* NONE */
void (*dlexit) __P((void)); /* HAS_DLEXIT */
void *(*dlsym3) __P((void *, char *, void *)); /* HAS_DLSYM3 */
};
/*

21
lib/csu/i386/crt0.c
View File

@ -27,7 +27,7 @@
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id$
* $Id: crt0.c,v 1.29 1997/02/22 14:57:44 peter Exp $
*/
#include <sys/param.h>
@ -94,6 +94,8 @@ static char empty[1];
char *__progname = empty;
char **environ;
static int ldso_version;
extern unsigned char etext;
extern unsigned char eprol asm ("eprol");
extern start() asm("start");
@ -194,7 +196,6 @@ __do_dynamic_link ()
struct exec hdr;
char *ldso;
int (*entry)();
int ret;
#ifdef DEBUG
/* Provision for alternate ld.so - security risk! */
@ -254,14 +255,14 @@ __do_dynamic_link ()
crt.crt_ldentry = NULL;
entry = (int (*)())(crt.crt_ba + sizeof hdr);
ret = (*entry)(CRT_VERSION_BSD_4, &crt);
ldso_version = (*entry)(CRT_VERSION_BSD_4, &crt);
ld_entry = crt.crt_ldentry;
if (ret == -1 && ld_entry == NULL) {
if (ldso_version == -1 && ld_entry == NULL) {
/* if version 4 not recognised, try version 3 */
ret = (*entry)(CRT_VERSION_BSD_3, &crt);
ldso_version = (*entry)(CRT_VERSION_BSD_3, &crt);
ld_entry = _DYNAMIC.d_entry;
}
if (ret == -1) {
if (ldso_version == -1) {
_PUTMSG("ld.so failed");
if (ld_entry != NULL) {
char *msg = (ld_entry->dlerror)();
@ -277,7 +278,7 @@ __do_dynamic_link ()
}
if (ret >= LDSO_VERSION_HAS_DLEXIT)
if (ldso_version >= LDSO_VERSION_HAS_DLEXIT)
atexit(ld_entry->dlexit);
return;
@ -316,7 +317,11 @@ char *name;
if (ld_entry == NULL)
return NULL;
return (ld_entry->dlsym)(fd, name);
if (ldso_version >= LDSO_VERSION_HAS_DLSYM3) {
void *retaddr = *(&fd - 1); /* XXX - ABI/machine dependent */
return (ld_entry->dlsym3)(fd, name, retaddr);
} else
return (ld_entry->dlsym)(fd, name);
}

7
lib/csu/i386/dlfcn.h
View File

@ -43,6 +43,13 @@
#define RTLD_LAZY 1 /* Bind function calls lazily */
#define RTLD_NOW 2 /* Bind function calls immediately */
/*
* Special handle argument for dlsym(). It causes the search for the
* symbol to begin in the next shared object after the one containing
* the caller.
*/
#define RTLD_NEXT ((void *) -1)
__BEGIN_DECLS
void *dlopen __P((char *, int));
void *dlsym __P((void *, char *));

22
lib/csu/i386/dlopen.3
View File

@ -152,6 +152,28 @@ returns a null pointer if the symbol cannot be found, and sets an error
condition which may be queried with
.Fn dlerror .
.Pp
If
.Fn dlsym
is called with the special
.Fa handle
.Dv RTLD_NEXT ,
then the search for the symbol is limited to the shared objects
which were loaded after the one issuing the call to
.Fn dlsym .
Thus, if the function is called from the main program, all
the shared libraries are searched.
If it is called from a shared library, all subsequent shared
libraries are searched.
.Dv RTLD_NEXT
is useful for implementing wrappers around library functions.
For example, a wrapper function
.Fn getpid
could access the
.Dq real
.Fn getpid
with
.Li dlsym(RTLD_NEXT, \&"_getpid\&") .
.Pp
.Fn dlerror
returns a null-terminated character string describing the last error that
occurred during a call to

76
libexec/rtld-aout/rtld.c
View File

@ -27,7 +27,7 @@
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id$
* $Id: rtld.c,v 1.46 1997/02/22 15:46:48 peter Exp $
*/
#include <sys/param.h>
@ -204,9 +204,10 @@ static int __dlclose __P((void *));
static void *__dlsym __P((void *, char *));
static char *__dlerror __P((void));
static void __dlexit __P((void));
static void *__dlsym3 __P((void *, char *, void *));
static struct ld_entry ld_entry = {
__dlopen, __dlclose, __dlsym, __dlerror, __dlexit
__dlopen, __dlclose, __dlsym, __dlerror, __dlexit, __dlsym3
};
void xprintf __P((char *, ...));
@ -411,7 +412,7 @@ struct _dynamic *dp;
(void)close(crtp->crt_ldfd);
anon_close();
return LDSO_VERSION_HAS_DLEXIT;
return LDSO_VERSION_HAS_DLSYM3;
}
void
@ -1896,26 +1897,77 @@ __dlclose(fd)
return 0;
}
/*
* This form of dlsym is obsolete. Current versions of crt0 don't call
* it. It can still be called by old executables that were linked with
* old versions of crt0.
*/
static void *
__dlsym(fd, sym)
void *fd;
char *sym;
{
struct so_map *smp = (struct so_map *)fd, *src_map = NULL;
if (fd == RTLD_NEXT) {
generror("RTLD_NEXT not supported by this version of"
" /usr/lib/crt0.o");
return NULL;
}
return __dlsym3(fd, sym, NULL);
}
static void *
__dlsym3(fd, sym, retaddr)
void *fd;
char *sym;
void *retaddr;
{
struct so_map *smp;
struct so_map *src_map;
struct nzlist *np;
long addr;
/*
* Restrict search to passed map if dlopen()ed.
*/
if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_DL)
src_map = smp;
if (fd == RTLD_NEXT) {
/* Find the shared object that contains the caller. */
for (smp = link_map_head; smp != NULL; smp = smp->som_next) {
void *textbase = smp->som_addr + LM_TXTADDR(smp);
void *textlimit = LM_ETEXT(smp);
np = lookup(sym, &src_map, 1);
if (np == NULL)
if (textbase <= retaddr && retaddr < textlimit)
break;
}
if (smp == NULL) {
generror("Cannot determine caller's shared object");
return NULL;
}
smp = smp->som_next;
if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_RTLD)
smp = smp->som_next;
if (smp == NULL) {
generror("No next shared object for RTLD_NEXT");
return NULL;
}
do {
src_map = smp;
np = lookup(sym, &src_map, 1);
} while (np == NULL && (smp = smp->som_next) != NULL);
} else {
smp = (struct so_map *)fd;
src_map = NULL;
/*
* Restrict search to passed map if dlopen()ed.
*/
if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_DL)
src_map = smp;
np = lookup(sym, &src_map, 1);
}
if (np == NULL) {
generror("Undefined symbol");
return NULL;
}
/* Fixup jmpslot so future calls transfer directly to target */
addr = np->nz_value;
if (src_map)
addr += (long)src_map->som_addr;

4
sys/sys/link_aout.h
View File

@ -27,7 +27,7 @@
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id: link.h,v 1.12 1997/05/07 02:26:34 eivind Exp $
* $Id: link.h,v 1.13 1997/05/07 20:00:00 eivind Exp $
*/
/*
@ -167,6 +167,7 @@ struct so_debug {
*/
#define LDSO_VERSION_NONE 0 /* FreeBSD2.0, 2.0.5 */
#define LDSO_VERSION_HAS_DLEXIT 1 /* includes dlexit in ld_entry */
#define LDSO_VERSION_HAS_DLSYM3 2 /* includes 3-argument dlsym */
/*
* Entry points into ld.so - user interface to the run-time linker.
@ -179,6 +180,7 @@ struct ld_entry {
void *(*dlsym) __P((void *, char *)); /* NONE */
char *(*dlerror) __P((void)); /* NONE */
void (*dlexit) __P((void)); /* HAS_DLEXIT */
void *(*dlsym3) __P((void *, char *, void *)); /* HAS_DLSYM3 */
};
/*

4
sys/sys/link_elf.h
View File

@ -27,7 +27,7 @@
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id: link.h,v 1.12 1997/05/07 02:26:34 eivind Exp $
* $Id: link.h,v 1.13 1997/05/07 20:00:00 eivind Exp $
*/
/*
@ -167,6 +167,7 @@ struct so_debug {
*/
#define LDSO_VERSION_NONE 0 /* FreeBSD2.0, 2.0.5 */
#define LDSO_VERSION_HAS_DLEXIT 1 /* includes dlexit in ld_entry */
#define LDSO_VERSION_HAS_DLSYM3 2 /* includes 3-argument dlsym */
/*
* Entry points into ld.so - user interface to the run-time linker.
@ -179,6 +180,7 @@ struct ld_entry {
void *(*dlsym) __P((void *, char *)); /* NONE */
char *(*dlerror) __P((void)); /* NONE */
void (*dlexit) __P((void)); /* HAS_DLEXIT */
void *(*dlsym3) __P((void *, char *, void *)); /* HAS_DLSYM3 */
};
/*