From e76526ff079a6b1f79c5456e258536f658115489 Mon Sep 17 00:00:00 2001
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From: Florian Weimer <fweimer@redhat.com>
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Date: Tue, 12 Nov 2019 12:41:34 +0100
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Subject: [PATCH 03/19] slotinfo in struct dtv_slotinfo_list should be flexible
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array [BZ #25097]
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GCC 10 will warn about subscribing inner length zero arrays. Use a GCC
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extension in csu/libc-tls.c to allocate space for the static_slotinfo
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variable. Adjust nptl_db so that the type description machinery does
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not attempt to determine the size of the flexible array member slotinfo.
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Change-Id: I51be146a7857186a4ede0bb40b332509487bdde8
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(cherry picked from commit cba932a5a9e91cffd7f4172d7e91f9b2efb1f84b)
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Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
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---
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csu/libc-tls.c | 34 ++++++++++++++--------------------
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nptl_db/db-symbols.h | 3 +++
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nptl_db/db_info.c | 6 ++++++
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nptl_db/structs.def | 2 +-
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nptl_db/thread_dbP.h | 4 ++++
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sysdeps/generic/ldsodefs.h | 2 +-
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6 files changed, 29 insertions(+), 22 deletions(-)
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diff --git a/csu/libc-tls.c b/csu/libc-tls.c
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index a36d1d49..aac7c853 100644
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--- a/csu/libc-tls.c
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+++ b/csu/libc-tls.c
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@@ -23,7 +23,7 @@
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#include <unistd.h>
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#include <stdio.h>
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#include <sys/param.h>
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-
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+#include <array_length.h>
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#ifdef SHARED
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#error makefile bug, this file is for static only
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@@ -32,17 +32,11 @@
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dtv_t _dl_static_dtv[2 + TLS_SLOTINFO_SURPLUS];
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-static struct
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-{
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- struct dtv_slotinfo_list si;
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- /* The dtv_slotinfo_list data structure does not include the actual
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- information since it is defined as an array of size zero. We define
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- here the necessary entries. Note that it is not important whether
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- there is padding or not since we will always access the information
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- through the 'si' element. */
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- struct dtv_slotinfo info[2 + TLS_SLOTINFO_SURPLUS];
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-} static_slotinfo;
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-
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+static struct dtv_slotinfo_list static_slotinfo =
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+ {
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+ /* Allocate an array of 2 + TLS_SLOTINFO_SURPLUS elements. */
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+ .slotinfo = { [array_length (_dl_static_dtv) - 1] = { 0 } },
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+ };
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/* Highest dtv index currently needed. */
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size_t _dl_tls_max_dtv_idx;
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@@ -72,16 +66,16 @@ TLS_INIT_HELPER
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static void
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init_slotinfo (void)
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{
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- /* Create the slotinfo list. */
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- static_slotinfo.si.len = (((char *) (&static_slotinfo + 1)
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- - (char *) &static_slotinfo.si.slotinfo[0])
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- / sizeof static_slotinfo.si.slotinfo[0]);
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- // static_slotinfo.si.next = NULL; already zero
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+ /* Create the slotinfo list. Note that the type of static_slotinfo
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+ has effectively a zero-length array, so we cannot use the size of
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+ static_slotinfo to determine the array length. */
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+ static_slotinfo.len = array_length (_dl_static_dtv);
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+ /* static_slotinfo.next = NULL; -- Already zero. */
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/* The slotinfo list. Will be extended by the code doing dynamic
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linking. */
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GL(dl_tls_max_dtv_idx) = 1;
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- GL(dl_tls_dtv_slotinfo_list) = &static_slotinfo.si;
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+ GL(dl_tls_dtv_slotinfo_list) = &static_slotinfo;
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}
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static void
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@@ -205,8 +199,8 @@ __libc_setup_tls (void)
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main_map->l_tls_modid = 1;
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init_slotinfo ();
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- // static_slotinfo.si.slotinfo[1].gen = 0; already zero
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- static_slotinfo.si.slotinfo[1].map = main_map;
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+ /* static_slotinfo.slotinfo[1].gen = 0; -- Already zero. */
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+ static_slotinfo.slotinfo[1].map = main_map;
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memsz = roundup (memsz, align ?: 1);
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diff --git a/nptl_db/db-symbols.h b/nptl_db/db-symbols.h
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index 2a44404f..2d9dd88a 100644
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--- a/nptl_db/db-symbols.h
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+++ b/nptl_db/db-symbols.h
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@@ -25,6 +25,7 @@
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DB_LOOKUP_NAME (SYM_SIZEOF_##type, _thread_db_sizeof_##type)
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#define DB_STRUCT_FIELD(type, field) \
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DB_LOOKUP_NAME (SYM_##type##_FIELD_##field, _thread_db_##type##_##field)
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+#define DB_STRUCT_FLEXIBLE_ARRAY(type, field) DB_STRUCT_FIELD (type, field)
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#define DB_SYMBOL(name) \
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DB_LOOKUP_NAME (SYM_##name, name)
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#define DB_FUNCTION(name) \
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@@ -36,6 +37,8 @@
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# include "structs.def"
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# undef DB_STRUCT
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+# undef DB_STRUCT_FIELD
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+# undef DB_STRUCT_FLEXIBLE_ARRAY
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# undef DB_FUNCTION
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# undef DB_SYMBOL
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# undef DB_VARIABLE
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diff --git a/nptl_db/db_info.c b/nptl_db/db_info.c
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index 8c2da41b..4a250159 100644
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--- a/nptl_db/db_info.c
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+++ b/nptl_db/db_info.c
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@@ -56,6 +56,9 @@ extern bool __nptl_initial_report_events;
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DB_DEFINE_DESC (name, \
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8 * sizeof (obj)[0], sizeof (obj) / sizeof (obj)[0], \
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offset);
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+/* Flexible arrays do not have a length that can be determined. */
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+#define FLEXIBLE_ARRAY_DESC(name, offset, obj) \
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+ DB_DEFINE_DESC (name, 8 * sizeof (obj)[0], 0, offset);
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#if TLS_TCB_AT_TP
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# define dtvp header.dtv
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@@ -77,6 +80,9 @@ DESC (_thread_db_pthread_dtvp,
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#define DB_STRUCT_ARRAY_FIELD(type, field) \
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ARRAY_DESC (_thread_db_##type##_##field, \
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offsetof (type, field), ((type *) 0)->field)
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+#define DB_STRUCT_FLEXIBLE_ARRAY(type, field) \
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+ FLEXIBLE_ARRAY_DESC (_thread_db_##type##_##field, \
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+ offsetof (type, field), ((type *) 0)->field)
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#define DB_VARIABLE(name) DESC (_thread_db_##name, 0, name)
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#define DB_ARRAY_VARIABLE(name) ARRAY_DESC (_thread_db_##name, 0, name)
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#define DB_SYMBOL(name) /* Nothing. */
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diff --git a/nptl_db/structs.def b/nptl_db/structs.def
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index 0d5b65c9..1fbfff18 100644
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--- a/nptl_db/structs.def
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+++ b/nptl_db/structs.def
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@@ -110,7 +110,7 @@ DB_RTLD_GLOBAL_FIELD (dl_tls_dtv_slotinfo_list)
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DB_STRUCT (dtv_slotinfo_list)
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DB_STRUCT_FIELD (dtv_slotinfo_list, len)
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DB_STRUCT_FIELD (dtv_slotinfo_list, next)
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-DB_STRUCT_ARRAY_FIELD (dtv_slotinfo_list, slotinfo)
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+DB_STRUCT_FLEXIBLE_ARRAY (dtv_slotinfo_list, slotinfo)
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DB_STRUCT (dtv_slotinfo)
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DB_STRUCT_FIELD (dtv_slotinfo, gen)
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diff --git a/nptl_db/thread_dbP.h b/nptl_db/thread_dbP.h
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index 262c0d2e..bc2094bf 100644
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--- a/nptl_db/thread_dbP.h
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+++ b/nptl_db/thread_dbP.h
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@@ -37,12 +37,14 @@ enum
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{
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# define DB_STRUCT(type) SYM_SIZEOF_##type,
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# define DB_STRUCT_FIELD(type, field) SYM_##type##_FIELD_##field,
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+# define DB_STRUCT_FLEXIBLE_ARRAY(type, field) DB_STRUCT_FIELD (type, field)
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# define DB_SYMBOL(name) SYM_##name,
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# define DB_FUNCTION(name) SYM_##name,
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# define DB_VARIABLE(name) SYM_##name, SYM_DESC_##name,
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# include "structs.def"
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# undef DB_STRUCT
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# undef DB_STRUCT_FIELD
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+# undef DB_STRUCT_FLEXIBLE_ARRAY
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# undef DB_SYMBOL
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# undef DB_FUNCTION
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# undef DB_VARIABLE
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@@ -90,6 +92,7 @@ struct td_thragent
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uint32_t ta_sizeof_##type;
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# define DB_STRUCT_FIELD(type, field) \
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db_desc_t ta_field_##type##_##field;
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+# define DB_STRUCT_FLEXIBLE_ARRAY(type, field) DB_STRUCT_FIELD (type, field)
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# define DB_SYMBOL(name) \
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psaddr_t ta_addr_##name;
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# define DB_FUNCTION(name) \
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@@ -100,6 +103,7 @@ struct td_thragent
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# include "structs.def"
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# undef DB_STRUCT
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# undef DB_STRUCT_FIELD
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+# undef DB_STRUCT_FLEXIBLE_ARRAY
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# undef DB_FUNCTION
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# undef DB_SYMBOL
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# undef DB_VARIABLE
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diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
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index 37cab6f0..52eca9d0 100644
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--- a/sysdeps/generic/ldsodefs.h
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+++ b/sysdeps/generic/ldsodefs.h
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@@ -408,7 +408,7 @@ struct rtld_global
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{
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size_t gen;
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struct link_map *map;
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- } slotinfo[0];
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+ } slotinfo[];
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} *_dl_tls_dtv_slotinfo_list;
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/* Number of modules in the static TLS block. */
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EXTERN size_t _dl_tls_static_nelem;
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--
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2.20.1
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