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250 lines
9.2 KiB
250 lines
9.2 KiB
commit c1cb2deeca1a85c6fc5bd41b90816d48a95bc434 |
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Author: Florian Weimer <fweimer@redhat.com> |
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Date: Sun Dec 5 11:28:34 2021 +0100 |
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elf: execve statically linked programs instead of crashing [BZ #28648] |
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Programs without dynamic dependencies and without a program |
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interpreter are now run via execve. |
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Previously, the dynamic linker either crashed while attempting to |
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read a non-existing dynamic segment (looking for DT_AUDIT/DT_DEPAUDIT |
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data), or the self-relocated in the static PIE executable crashed |
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because the outer dynamic linker had already applied RELRO protection. |
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<dl-execve.h> is needed because execve is not available in the |
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dynamic loader on Hurd. |
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Reviewed-by: H.J. Lu <hjl.tools@gmail.com> |
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Conflicts: |
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elf/Makefile |
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(usual test differences) |
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elf/rtld.c |
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(missing ld.so self-relocation cleanup downstream) |
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diff --git a/elf/Makefile b/elf/Makefile |
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index 118d579c42c38110..7696aa1324919a80 100644 |
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--- a/elf/Makefile |
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+++ b/elf/Makefile |
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@@ -224,7 +224,8 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \ |
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tst-tls-ie tst-tls-ie-dlmopen argv0test \ |
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tst-glibc-hwcaps tst-glibc-hwcaps-prepend tst-glibc-hwcaps-mask \ |
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tst-tls20 tst-tls21 tst-dlmopen-dlerror tst-dlmopen-gethostbyname \ |
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- tst-dl-is_dso tst-ro-dynamic |
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+ tst-dl-is_dso tst-ro-dynamic \ |
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+ tst-rtld-run-static \ |
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# reldep9 |
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tests-internal += loadtest unload unload2 circleload1 \ |
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neededtest neededtest2 neededtest3 neededtest4 \ |
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@@ -1914,3 +1915,5 @@ $(objpfx)tst-ro-dynamic-mod.so: $(objpfx)tst-ro-dynamic-mod.os \ |
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$(LINK.o) -nostdlib -nostartfiles -shared -o $@ \ |
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-Wl,--script=tst-ro-dynamic-mod.map \ |
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$(objpfx)tst-ro-dynamic-mod.os |
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+ |
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+$(objpfx)tst-rtld-run-static.out: $(objpfx)/ldconfig |
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diff --git a/elf/rtld.c b/elf/rtld.c |
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index d83ac1bdc40a6081..6b0d6107801b2f44 100644 |
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--- a/elf/rtld.c |
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+++ b/elf/rtld.c |
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@@ -50,6 +50,7 @@ |
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#include <dl-main.h> |
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#include <gnu/lib-names.h> |
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#include <dl-tunables.h> |
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+#include <dl-execve.h> |
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#include <assert.h> |
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@@ -1106,6 +1107,45 @@ load_audit_modules (struct link_map *main_map, struct audit_list *audit_list) |
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} |
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} |
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+/* Check if the executable is not actualy dynamically linked, and |
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+ invoke it directly in that case. */ |
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+static void |
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+rtld_chain_load (struct link_map *main_map, char *argv0) |
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+{ |
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+ /* The dynamic loader run against itself. */ |
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+ const char *rtld_soname |
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+ = ((const char *) D_PTR (&GL(dl_rtld_map), l_info[DT_STRTAB]) |
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+ + GL(dl_rtld_map).l_info[DT_SONAME]->d_un.d_val); |
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+ if (main_map->l_info[DT_SONAME] != NULL |
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+ && strcmp (rtld_soname, |
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+ ((const char *) D_PTR (main_map, l_info[DT_STRTAB]) |
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+ + main_map->l_info[DT_SONAME]->d_un.d_val)) == 0) |
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+ _dl_fatal_printf ("%s: loader cannot load itself\n", rtld_soname); |
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+ |
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+ /* With DT_NEEDED dependencies, the executable is dynamically |
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+ linked. */ |
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+ if (__glibc_unlikely (main_map->l_info[DT_NEEDED] != NULL)) |
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+ return; |
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+ |
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+ /* If the executable has program interpreter, it is dynamically |
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+ linked. */ |
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+ for (size_t i = 0; i < main_map->l_phnum; ++i) |
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+ if (main_map->l_phdr[i].p_type == PT_INTERP) |
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+ return; |
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+ |
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+ const char *pathname = _dl_argv[0]; |
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+ if (argv0 != NULL) |
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+ _dl_argv[0] = argv0; |
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+ int errcode = __rtld_execve (pathname, _dl_argv, _environ); |
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+ const char *errname = strerrorname_np (errcode); |
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+ if (errname != NULL) |
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+ _dl_fatal_printf("%s: cannot execute %s: %s\n", |
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+ rtld_soname, pathname, errname); |
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+ else |
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+ _dl_fatal_printf("%s: cannot execute %s: %d\n", |
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+ rtld_soname, pathname, errno); |
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+} |
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+ |
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static void |
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dl_main (const ElfW(Phdr) *phdr, |
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ElfW(Word) phnum, |
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@@ -1374,14 +1414,8 @@ dl_main (const ElfW(Phdr) *phdr, |
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/* Now the map for the main executable is available. */ |
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main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded; |
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- if (__glibc_likely (state.mode == rtld_mode_normal) |
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- && GL(dl_rtld_map).l_info[DT_SONAME] != NULL |
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- && main_map->l_info[DT_SONAME] != NULL |
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- && strcmp ((const char *) D_PTR (&GL(dl_rtld_map), l_info[DT_STRTAB]) |
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- + GL(dl_rtld_map).l_info[DT_SONAME]->d_un.d_val, |
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- (const char *) D_PTR (main_map, l_info[DT_STRTAB]) |
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- + main_map->l_info[DT_SONAME]->d_un.d_val) == 0) |
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- _dl_fatal_printf ("loader cannot load itself\n"); |
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+ if (__glibc_likely (state.mode == rtld_mode_normal)) |
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+ rtld_chain_load (main_map, argv0); |
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phdr = main_map->l_phdr; |
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phnum = main_map->l_phnum; |
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diff --git a/elf/tst-rtld-run-static.c b/elf/tst-rtld-run-static.c |
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new file mode 100644 |
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index 0000000000000000..7281093504b675c4 |
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--- /dev/null |
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+++ b/elf/tst-rtld-run-static.c |
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@@ -0,0 +1,62 @@ |
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+/* Test running statically linked programs using ld.so. |
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+ Copyright (C) 2021 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 <support/check.h> |
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+#include <support/support.h> |
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+#include <support/capture_subprocess.h> |
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+#include <string.h> |
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+#include <stdlib.h> |
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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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+ char *ldconfig_path = xasprintf ("%s/elf/ldconfig", support_objdir_root); |
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+ |
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+ { |
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+ char *argv[] = { (char *) "ld.so", ldconfig_path, (char *) "--help", NULL }; |
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+ struct support_capture_subprocess cap |
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+ = support_capture_subprogram (support_objdir_elf_ldso, argv); |
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+ support_capture_subprocess_check (&cap, "no --argv0", 0, sc_allow_stdout); |
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+ puts ("info: output without --argv0:"); |
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+ puts (cap.out.buffer); |
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+ TEST_VERIFY (strstr (cap.out.buffer, "Usage: ldconfig [OPTION...]\n") |
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+ == cap.out.buffer); |
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+ support_capture_subprocess_free (&cap); |
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+ } |
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+ |
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+ { |
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+ char *argv[] = |
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+ { |
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+ (char *) "ld.so", (char *) "--argv0", (char *) "ldconfig-argv0", |
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+ ldconfig_path, (char *) "--help", NULL |
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+ }; |
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+ struct support_capture_subprocess cap |
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+ = support_capture_subprogram (support_objdir_elf_ldso, argv); |
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+ support_capture_subprocess_check (&cap, "with --argv0", 0, sc_allow_stdout); |
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+ puts ("info: output with --argv0:"); |
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+ puts (cap.out.buffer); |
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+ TEST_VERIFY (strstr (cap.out.buffer, "Usage: ldconfig-argv0 [OPTION...]\n") |
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+ == cap.out.buffer); |
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+ support_capture_subprocess_free (&cap); |
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+ } |
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+ |
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+ free (ldconfig_path); |
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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/sysdeps/generic/dl-execve.h b/sysdeps/generic/dl-execve.h |
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new file mode 100644 |
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index 0000000000000000..5fd097df69e1770c |
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--- /dev/null |
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+++ b/sysdeps/generic/dl-execve.h |
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@@ -0,0 +1,25 @@ |
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+/* execve for the dynamic linker. Generic stub version. |
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+ Copyright (C) 2021 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 <errno.h> |
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+ |
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+static int |
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+__rtld_execve (const char *path, char *const *argv, char *const *envp) |
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+{ |
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+ return ENOSYS; |
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+} |
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diff --git a/sysdeps/unix/sysv/linux/dl-execve.h b/sysdeps/unix/sysv/linux/dl-execve.h |
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new file mode 100644 |
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index 0000000000000000..ead3e1c28da34363 |
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--- /dev/null |
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+++ b/sysdeps/unix/sysv/linux/dl-execve.h |
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@@ -0,0 +1,25 @@ |
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+/* execve for the dynamic linker. Linux version. |
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+ Copyright (C) 2021 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 <errno.h> |
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+ |
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+static inline int |
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+__rtld_execve (const char *path, char *const *argv, char *const *envp) |
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+{ |
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+ return -INTERNAL_SYSCALL_CALL (execve, path, argv, envp); |
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+}
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