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256 lines
8.1 KiB
256 lines
8.1 KiB
commit 91c2e6c3db44297bf4cb3a2e3c40236c5b6a0b23 |
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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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(cherry picked from commit d056c212130280c0a54d9a4f72170ec621b70ce5) |
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diff --git a/dlfcn/Makefile b/dlfcn/Makefile |
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index 6bbfbb8344da05cb..d3965427dabed898 100644 |
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--- a/dlfcn/Makefile |
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+++ b/dlfcn/Makefile |
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@@ -73,6 +73,10 @@ 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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diff --git a/dlfcn/dlfcn.h b/dlfcn/dlfcn.h |
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index 4a3b870a487ea789..24388cfedae4dd67 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 47d2daa96fa5986f..1842925fb7c594dd 100644 |
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--- a/dlfcn/dlinfo.c |
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+++ b/dlfcn/dlinfo.c |
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@@ -28,6 +28,10 @@ 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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@@ -40,6 +44,7 @@ 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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@@ -75,6 +80,11 @@ 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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@@ -82,7 +92,8 @@ static int |
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dlinfo_implementation (void *handle, int request, void *arg) |
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{ |
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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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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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