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From f553dc066071a4465321fbc122bed8a75afd996b Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Thu, 22 Apr 2021 11:07:43 +0200
Subject: [PATCH 405/576] nptl: Check for compatible GDB in
nptl/tst-pthread-gdb-attach
Also do not clear the subprocess environment, in case running
GDB needs certain environment variables.
---
nptl/tst-pthread-gdb-attach.c | 78 ++++++++++++++++++++++++++++++++++-
1 file changed, 76 insertions(+), 2 deletions(-)
diff --git a/nptl/tst-pthread-gdb-attach.c b/nptl/tst-pthread-gdb-attach.c
index 0603ad844d..901a120034 100644
--- a/nptl/tst-pthread-gdb-attach.c
+++ b/nptl/tst-pthread-gdb-attach.c
@@ -20,8 +20,12 @@
whether libthread_db can be loaded, and that access to thread-local
variables works. */
+#include <elf.h>
#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
#include <stdlib.h>
+#include <string.h>
#include <support/check.h>
#include <support/support.h>
#include <support/temp_file.h>
@@ -35,6 +39,49 @@
the thread. */
__thread volatile int altered_by_debugger;
+/* Common prefix between 32-bit and 64-bit ELF. */
+struct elf_prefix
+{
+ unsigned char e_ident[EI_NIDENT];
+ uint16_t e_type;
+ uint16_t e_machine;
+ uint32_t e_version;
+};
+_Static_assert (sizeof (struct elf_prefix) == EI_NIDENT + 8,
+ "padding in struct elf_prefix");
+
+/* Reads the ELF header from PATH. Returns true if the header can be
+ read, false if the file is too short. */
+static bool
+read_elf_header (const char *path, struct elf_prefix *elf)
+{
+ int fd = xopen (path, O_RDONLY, 0);
+ bool result = read (fd, elf, sizeof (*elf)) == sizeof (*elf);
+ xclose (fd);
+ return result;
+}
+
+/* Searches for "gdb" alongside the path variable. See execvpe. */
+static char *
+find_gdb (void)
+{
+ const char *path = getenv ("PATH");
+ if (path == NULL)
+ return NULL;
+ while (true)
+ {
+ const char *colon = strchrnul (path, ':');
+ char *candidate = xasprintf ("%.*s/gdb", (int) (colon - path), path);
+ if (access (candidate, X_OK) == 0)
+ return candidate;
+ free (candidate);
+ if (*colon == '\0')
+ break;
+ path = colon + 1;
+ }
+ return NULL;
+}
+
/* Writes the GDB script to run the test to PATH. */
static void
write_gdbscript (const char *path, int tested_pid)
@@ -105,6 +152,33 @@ in_subprocess (void)
static int
do_test (void)
{
+ char *gdb_path = find_gdb ();
+ if (gdb_path == NULL)
+ FAIL_UNSUPPORTED ("gdb command not found in PATH: %s", getenv ("PATH"));
+
+ /* Check that libthread_db is compatible with the gdb architecture
+ because gdb loads it via dlopen. */
+ {
+ char *threaddb_path = xasprintf ("%s/nptl_db/libthread_db.so",
+ support_objdir_root);
+ struct elf_prefix elf_threaddb;
+ TEST_VERIFY_EXIT (read_elf_header (threaddb_path, &elf_threaddb));
+ struct elf_prefix elf_gdb;
+ /* If the ELF header cannot be read or "gdb" is not an ELF file,
+ assume this is a wrapper script that can run. */
+ if (read_elf_header (gdb_path, &elf_gdb)
+ && memcmp (&elf_gdb, ELFMAG, SELFMAG) == 0)
+ {
+ if (elf_gdb.e_ident[EI_CLASS] != elf_threaddb.e_ident[EI_CLASS])
+ FAIL_UNSUPPORTED ("GDB at %s has wrong class", gdb_path);
+ if (elf_gdb.e_ident[EI_DATA] != elf_threaddb.e_ident[EI_DATA])
+ FAIL_UNSUPPORTED ("GDB at %s has wrong data", gdb_path);
+ if (elf_gdb.e_machine != elf_threaddb.e_machine)
+ FAIL_UNSUPPORTED ("GDB at %s has wrong machine", gdb_path);
+ }
+ free (threaddb_path);
+ }
+
pid_t tested_pid = xfork ();
if (tested_pid == 0)
in_subprocess ();
@@ -117,9 +191,8 @@ do_test (void)
pid_t gdb_pid = xfork ();
if (gdb_pid == 0)
{
- clearenv ();
xdup2 (STDOUT_FILENO, STDERR_FILENO);
- execlp ("gdb", "gdb", "-nx", "-batch", "-x", gdbscript, NULL);
+ execl (gdb_path, "gdb", "-nx", "-batch", "-x", gdbscript, NULL);
if (errno == ENOENT)
_exit (EXIT_UNSUPPORTED);
else
@@ -137,6 +210,7 @@ do_test (void)
free (tested_pid_string);
free (gdbscript);
+ free (gdb_path);
return 0;
}
--
2.31.1
|