forked from rpms/glibc
269 lines
8.4 KiB
Diff
269 lines
8.4 KiB
Diff
Added $(objpfx)tst-dlinfo-phdr: $(libdl) to dlfcn/Makefile since
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we still need $(libdl) in RHEL8.
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commit d056c212130280c0a54d9a4f72170ec621b70ce5
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Fri Apr 29 17:00:53 2022 +0200
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dlfcn: Implement the RTLD_DI_PHDR request type for dlinfo
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The information is theoretically available via dl_iterate_phdr as
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well, but that approach is very slow if there are many shared
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objects.
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Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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Tested-by: Carlos O'Donell <carlos@rehdat.com>
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Conflicts:
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dlfcn/dlinfo.c
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(missing move into libc)
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diff --git a/dlfcn/Makefile b/dlfcn/Makefile
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index 0b213b7d9fefcdc9..65cee5b54d891a24 100644
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--- a/dlfcn/Makefile
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+++ b/dlfcn/Makefile
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@@ -59,6 +59,10 @@ tststatic3-ENV = $(tststatic-ENV)
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tststatic4-ENV = $(tststatic-ENV)
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tststatic5-ENV = $(tststatic-ENV)
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+tests-internal += \
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+ tst-dlinfo-phdr \
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+ # tests-internal
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+
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ifneq (,$(CXX))
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modules-names += bug-atexit3-lib
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else
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@@ -152,3 +156,5 @@ $(objpfx)bug-dl-leaf-lib-cb.so: $(objpfx)bug-dl-leaf-lib.so
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$(objpfx)tst-rec-dlopen: $(libdl)
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$(objpfx)tst-rec-dlopen.out: $(objpfx)moddummy1.so $(objpfx)moddummy2.so
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+
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+$(objpfx)tst-dlinfo-phdr: $(libdl)
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diff --git a/dlfcn/dlfcn.h b/dlfcn/dlfcn.h
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index 0921fd724cf7b785..61c4f59bea4eb7ac 100644
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--- a/dlfcn/dlfcn.h
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+++ b/dlfcn/dlfcn.h
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@@ -162,7 +162,12 @@ enum
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segment, or if the calling thread has not allocated a block for it. */
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RTLD_DI_TLS_DATA = 10,
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- RTLD_DI_MAX = 10
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+ /* Treat ARG as const ElfW(Phdr) **, and store the address of the
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+ program header array at that location. The dlinfo call returns
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+ the number of program headers in the array. */
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+ RTLD_DI_PHDR = 11,
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+
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+ RTLD_DI_MAX = 11
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};
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diff --git a/dlfcn/dlinfo.c b/dlfcn/dlinfo.c
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index 23ef3f57ca41afdf..50cd9af17a56f990 100644
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--- a/dlfcn/dlinfo.c
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+++ b/dlfcn/dlinfo.c
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@@ -38,6 +38,10 @@ struct dlinfo_args
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void *handle;
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int request;
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void *arg;
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+
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+ /* This is the value that is returned from dlinfo if no error is
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+ signaled. */
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+ int result;
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};
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static void
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@@ -50,6 +54,7 @@ dlinfo_doit (void *argsblock)
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{
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case RTLD_DI_CONFIGADDR:
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default:
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+ args->result = -1;
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_dl_signal_error (0, NULL, NULL, N_("unsupported dlinfo request"));
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break;
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@@ -85,6 +90,11 @@ dlinfo_doit (void *argsblock)
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*(void **) args->arg = data;
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break;
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}
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+
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+ case RTLD_DI_PHDR:
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+ *(const ElfW(Phdr) **) args->arg = l->l_phdr;
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+ args->result = l->l_phnum;
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+ break;
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}
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}
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@@ -97,7 +107,8 @@ __dlinfo (void *handle, int request, void *arg)
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# endif
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struct dlinfo_args args = { handle, request, arg };
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- return _dlerror_run (&dlinfo_doit, &args) ? -1 : 0;
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+ _dlerror_run (&dlinfo_doit, &args);
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+ return args.result;
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}
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# ifdef SHARED
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strong_alias (__dlinfo, dlinfo)
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diff --git a/dlfcn/tst-dlinfo-phdr.c b/dlfcn/tst-dlinfo-phdr.c
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new file mode 100644
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index 0000000000000000..a15a7d48ebd3b976
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--- /dev/null
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+++ b/dlfcn/tst-dlinfo-phdr.c
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@@ -0,0 +1,125 @@
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+/* Test for dlinfo (RTLD_DI_PHDR).
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+ Copyright (C) 2022 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <dlfcn.h>
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+#include <link.h>
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+#include <stdbool.h>
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+#include <stdio.h>
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+#include <string.h>
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+#include <sys/auxv.h>
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+
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+#include <support/check.h>
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+#include <support/xdlfcn.h>
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+
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+/* Used to verify that the program header array appears as expected
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+ among the dl_iterate_phdr callback invocations. */
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+
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+struct dlip_callback_args
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+{
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+ struct link_map *l; /* l->l_addr is used to find the object. */
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+ const ElfW(Phdr) *phdr; /* Expected program header pointed. */
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+ int phnum; /* Expected program header count. */
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+ bool found; /* True if l->l_addr has been found. */
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+};
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+
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+static int
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+dlip_callback (struct dl_phdr_info *dlpi, size_t size, void *closure)
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+{
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+ TEST_COMPARE (sizeof (*dlpi), size);
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+ struct dlip_callback_args *args = closure;
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+
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+ if (dlpi->dlpi_addr == args->l->l_addr)
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+ {
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+ TEST_VERIFY (!args->found);
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+ args->found = true;
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+ TEST_VERIFY (args->phdr == dlpi->dlpi_phdr);
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+ TEST_COMPARE (args->phnum, dlpi->dlpi_phnum);
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+ }
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+
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+ return 0;
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+}
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+
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+static int
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+do_test (void)
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+{
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+ /* Avoid a copy relocation. */
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+ struct r_debug *debug = xdlsym (RTLD_DEFAULT, "_r_debug");
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+ struct link_map *l = (struct link_map *) debug->r_map;
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+ TEST_VERIFY_EXIT (l != NULL);
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+
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+ do
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+ {
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+ printf ("info: checking link map %p (%p) for \"%s\"\n",
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+ l, l->l_phdr, l->l_name);
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+
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+ /* Cause dlerror () to return an error message. */
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+ dlsym (RTLD_DEFAULT, "does-not-exist");
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+
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+ /* Use the extension that link maps are valid dlopen handles. */
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+ const ElfW(Phdr) *phdr;
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+ int phnum = dlinfo (l, RTLD_DI_PHDR, &phdr);
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+ TEST_VERIFY (phnum >= 0);
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+ /* Verify that the error message has been cleared. */
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+ TEST_COMPARE_STRING (dlerror (), NULL);
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+
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+ TEST_VERIFY (phdr == l->l_phdr);
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+ TEST_COMPARE (phnum, l->l_phnum);
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+
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+ /* Check that we can find PT_DYNAMIC among the array. */
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+ {
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+ bool dynamic_found = false;
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+ for (int i = 0; i < phnum; ++i)
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+ if (phdr[i].p_type == PT_DYNAMIC)
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+ {
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+ dynamic_found = true;
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+ TEST_COMPARE ((ElfW(Addr)) l->l_ld, l->l_addr + phdr[i].p_vaddr);
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+ }
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+ TEST_VERIFY (dynamic_found);
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+ }
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+
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+ /* Check that dl_iterate_phdr finds the link map with the same
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+ program headers. */
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+ {
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+ struct dlip_callback_args args =
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+ {
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+ .l = l,
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+ .phdr = phdr,
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+ .phnum = phnum,
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+ .found = false,
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+ };
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+ TEST_COMPARE (dl_iterate_phdr (dlip_callback, &args), 0);
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+ TEST_VERIFY (args.found);
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+ }
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+
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+ if (l->l_prev == NULL)
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+ {
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+ /* This is the executable, so the information is also
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+ available via getauxval. */
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+ TEST_COMPARE_STRING (l->l_name, "");
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+ TEST_VERIFY (phdr == (const ElfW(Phdr) *) getauxval (AT_PHDR));
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+ TEST_COMPARE (phnum, getauxval (AT_PHNUM));
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+ }
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+
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+ l = l->l_next;
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+ }
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+ while (l != NULL);
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+
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+ return 0;
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+}
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+
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+#include <support/test-driver.c>
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diff --git a/manual/dynlink.texi b/manual/dynlink.texi
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index dbf3de11769d8e57..7dcac64889e389fd 100644
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--- a/manual/dynlink.texi
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+++ b/manual/dynlink.texi
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@@ -30,9 +30,9 @@ location @var{arg}, based on @var{request}. The @var{handle} argument
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must be a pointer returned by @code{dlopen} or @code{dlmopen}; it must
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not have been closed by @code{dlclose}.
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-On success, @code{dlinfo} returns 0. If there is an error, the function
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-returns @math{-1}, and @code{dlerror} can be used to obtain a
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-corresponding error message.
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+On success, @code{dlinfo} returns 0 for most request types; exceptions
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+are noted below. If there is an error, the function returns @math{-1},
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+and @code{dlerror} can be used to obtain a corresponding error message.
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The following operations are defined for use with @var{request}:
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@@ -84,6 +84,15 @@ This request writes the TLS module ID for the shared object @var{handle}
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to @code{*@var{arg}}. The argument @var{arg} must be the address of an
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object of type @code{size_t}. The module ID is zero if the object
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does not have an associated TLS block.
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+
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+@item RTLD_DI_PHDR
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+This request writes the address of the program header array to
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+@code{*@var{arg}}. The argument @var{arg} must be the address of an
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+object of type @code{const ElfW(Phdr) *} (that is,
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+@code{const Elf32_Phdr *} or @code{const Elf64_Phdr *}, as appropriate
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+for the current architecture). For this request, the value returned by
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+@code{dlinfo} is the number of program headers in the program header
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+array.
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@end vtable
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The @code{dlinfo} function is a GNU extension.
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