@@ -13,6 +13,7 @@ AUTHORS
copyr-*
copying.*
glibc-*
+!glibc-var.h
configparms
@@ -35,6 +35,7 @@ dl-routines = $(addprefix dl-,load lookup object reloc deps hwcaps \
ifeq (yes,$(use-ldconfig))
dl-routines += dl-cache
endif
+dl-routines += dl-glibc-var
all-dl-routines = $(dl-routines) $(sysdep-dl-routines)
# But they are absent from the shared libc, because that code is in ld.so.
elide-routines.os = $(all-dl-routines) dl-support enbl-secure dl-origin \
@@ -52,9 +52,11 @@ ld {
}
GLIBC_PRIVATE {
# Those are in the dynamic linker, but used by libc.so.
+ __glibc_var_init;
__libc_enable_secure;
_dl_allocate_tls; _dl_allocate_tls_init;
_dl_argv; _dl_find_dso_for_object; _dl_get_tls_static_info;
+ _dl_glibc_var;
_dl_deallocate_tls; _dl_make_stack_executable; _dl_out_of_memory;
_dl_rtld_di_serinfo; _dl_starting_up; _dl_tls_setup;
_rtld_global; _rtld_global_ro;
@@ -22,10 +22,10 @@
#include <ldsodefs.h>
/* Walk through the environment of the process and return all entries
- starting with `LD_'. */
+ starting with `LD_' or 'GLIBC_'. */
char *
internal_function
-_dl_next_ld_env_entry (char ***position)
+_dl_next_ld_env_entry (char ***position, char *first)
{
char **current = *position;
char *result = NULL;
@@ -35,6 +35,7 @@ _dl_next_ld_env_entry (char ***position)
if (__builtin_expect ((*current)[0] == 'L', 0)
&& (*current)[1] == 'D' && (*current)[2] == '_')
{
+ *first = (*current)[0];
result = &(*current)[3];
/* Save current position for next visit. */
@@ -43,6 +44,20 @@ _dl_next_ld_env_entry (char ***position)
break;
}
+ if (__builtin_expect ((*current)[0] == 'G', 0)
+ && (*current)[1] == 'L' && (*current)[2] == 'I'
+ && (*current)[3] == 'B' && (*current)[4] == 'C'
+ && (*current)[5] == '_')
+ {
+ *first = (*current)[0];
+ result = &(*current)[6];
+
+ /* Save current position for next visit. */
+ *position = ++current;
+
+ break;
+ }
+
++current;
}
new file mode 100644
@@ -0,0 +1,110 @@
+/* Fast access to GLIBC_* environment variables, without having to walk
+ the environment multiple times.
+ Copyright (C) 2013 Free Software Foundation, Inc.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <string.h>
+#include <glibc-var.h>
+
+#define _GLIBC_VAR_ENTRY(a) [GLIBC_VAR_##a] = { #a, sizeof(#a) - 1, NULL }
+
+struct glibc_var _dl_glibc_var[] =
+{
+ _GLIBC_VAR_ENTRY(PTHREAD_MUTEX),
+ _GLIBC_VAR_ENTRY(PTHREAD_RWLOCK),
+ /* Add more GLIBC_ variables here. */
+ /* Make the names as long as possible to pass code review. */
+ [GLIBC_VAR_MAX] = { NULL, 0, NULL }
+};
+
+internal_function void
+__record_glibc_var (char *name, int len, char *val)
+{
+ int i;
+
+ for (i = 0; i < GLIBC_VAR_MAX; i++)
+ {
+ struct glibc_var *v = &_dl_glibc_var[i];
+
+ if (len == v->len && memcmp (v->name, name, v->len) == 0)
+ {
+ v->val = val;
+ break;
+ }
+ }
+ /* Ignore unknown GLIBC_ variables. */
+}
+
+#ifndef SHARED
+
+/* If SHARED the env walk is shared with rtld.c. */
+
+static char *
+next_env_entry (char first, char ***position)
+{
+ char **current = *position;
+ char *result = NULL;
+
+ while (*current != NULL)
+ {
+ if ((*current)[0] == first)
+ {
+ result = *current;
+ *position = ++current;
+ break;
+ }
+
+ ++current;
+ }
+
+ return result;
+}
+
+/* May be called from libpthread. */
+
+void
+__glibc_var_init (int argc __attribute__ ((unused)),
+ char **argv __attribute__ ((unused)),
+ char **environ)
+{
+ char *envline;
+ static int initialized;
+
+ if (initialized != 0)
+ return;
+ initialized = 1;
+
+ while ((envline = next_env_entry ('G', &environ)) != NULL)
+ {
+ if (envline[1] == 'L' && envline[2] == 'I' && envline[3] == 'B'
+ && envline[4] == 'C' && envline[5] == '_')
+ {
+ char *e = envline + 6;
+ while (*e && *e != '=')
+ e++;
+ if (*e == 0)
+ continue;
+ __record_glibc_var (envline + 6, e - (envline + 6), e + 1);
+ }
+ }
+}
+
+void (*const __glibc_var_init_array []) (int, char **, char **)
+ __attribute__ ((section (".preinit_array"), aligned (sizeof (void *)))) =
+{
+ &__glibc_var_init
+};
+#endif
@@ -41,6 +41,7 @@
#include <tls.h>
#include <stap-probe.h>
#include <stackinfo.h>
+#include <glibc-var.h>
#include <assert.h>
@@ -2338,7 +2339,9 @@ process_dl_audit (char *str)
/* Process all environments variables the dynamic linker must recognize.
Since all of them start with `LD_' we are a bit smarter while finding
- all the entries. */
+ all the entries. In addition we also save a bunch of GLIBC_ variables
+ used by other parts of glibc, so that each startup only has to walk the
+ environment once. */
extern char **_environ attribute_hidden;
@@ -2349,12 +2352,13 @@ process_envvars (enum mode *modep)
char *envline;
enum mode mode = normal;
char *debug_output = NULL;
+ char first;
/* This is the default place for profiling data file. */
GLRO(dl_profile_output)
= &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
- while ((envline = _dl_next_ld_env_entry (&runp)) != NULL)
+ while ((envline = _dl_next_ld_env_entry (&runp, &first)) != NULL)
{
size_t len = 0;
@@ -2367,6 +2371,15 @@ process_envvars (enum mode *modep)
invalid memory below. */
continue;
+ /* Must be for GLIBC_ */
+ if (first == 'G')
+ {
+ __record_glibc_var (envline, len, envline + len + 1);
+ continue;
+ }
+
+ /* Must be for LD_ */
+
switch (len)
{
case 4:
new file mode 100644
@@ -0,0 +1,49 @@
+/* Fast access to GLIBC_* environment variables, without having to walk
+ the environment. Register new ones in in elf/glibc-var.c
+ Copyright (C) 2013 Free Software Foundation, Inc.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef _GLIBC_VAR_H
+# define _GLIBC_VAR_H 1
+
+# include <libc-symbols.h>
+
+enum
+{
+ GLIBC_VAR_PTHREAD_MUTEX,
+ GLIBC_VAR_PTHREAD_RWLOCK,
+ GLIBC_VAR_MAX
+};
+
+struct glibc_var
+{
+ const char *name;
+ int len;
+ char *val;
+};
+
+extern struct glibc_var _dl_glibc_var[];
+extern void __record_glibc_var (char *name, int len, char *val) internal_function;
+
+/* Call this if you're in a constructor that may run before glibc-var's. */
+# ifndef SHARED
+extern void __glibc_var_init (int ac, char **av, char **env);
+# else
+/* For shared this is always done in the dynamic linker early enough. */
+# define __glibc_var_init(a,b,c) do {} while (0)
+# endif
+
+#endif
@@ -893,9 +893,9 @@ extern void _dl_mcount_wrapper (void *selfpc);
/* Show the members of the auxiliary array passed up from the kernel. */
extern void _dl_show_auxv (void) internal_function;
-/* Return all environment variables starting with `LD_', one after the
- other. */
-extern char *_dl_next_ld_env_entry (char ***position) internal_function;
+/* Return all environment variables starting with `LD_' or `GLIBC_', one
+ after the other. */
+extern char *_dl_next_ld_env_entry (char ***position, char *first) internal_function;
/* Return an array with the names of the important hardware capabilities. */
extern const struct r_strlenpair *_dl_important_hwcaps (const char *platform,