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nptl: Check for compatible GDB in nptl/tst-pthread-gdb-attach

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Also do not clear the subprocess environment, in case running
GDB needs certain environment variables.
This commit is contained in:
Florian Weimer 2021-04-22 11:07:43 +02:00
parent 6573396163
commit f553dc0660
1 changed files with 76 additions and 2 deletions
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78
nptl/tst-pthread-gdb-attach.c
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@ -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;
}