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libselinux: rename gettid() to something which never conflicts with the libc 

Musl recently added a wrapper for gettid() syscall. There is no way to
detect this new version in a reliable way, so rename our gettid()
wrapper to a non-conflicting name.

Introduce a new function which, when using a libc known to provide a
wrapper for gettid(), calls it, and which, otherwise, performs the
syscall directly.

Anyway this function is only used on systems where /proc/thread-self
does not exist, which are therefore running Linux<3.17.

Fixes: https://github.com/SELinuxProject/selinux/issues/282
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
Acked-by: Petr Lautrbach <plautrba@redhat.com>
This commit is contained in:
Nicolas Iooss 2021-02-16 22:13:28 +01:00 committed by Petr Lautrbach
parent 8f0f0a28aa
commit 398d2ceef9
1 changed files with 10 additions and 8 deletions
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18
libselinux/src/procattr.c
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@ -25,21 +25,23 @@ static __thread char destructor_initialized;
/* Bionic and glibc >= 2.30 declare gettid() system call wrapper in unistd.h and
* has a definition for it */
#ifdef __BIONIC__
#define OVERRIDE_GETTID 0
#define HAVE_GETTID 1
#elif !defined(__GLIBC_PREREQ)
#define OVERRIDE_GETTID 1
#define HAVE_GETTID 0
#elif !__GLIBC_PREREQ(2,30)
#define OVERRIDE_GETTID 1
#define HAVE_GETTID 0
#else
#define OVERRIDE_GETTID 0
#define HAVE_GETTID 1
#endif
#if OVERRIDE_GETTID
static pid_t gettid(void)
static pid_t selinux_gettid(void)
{
#if HAVE_GETTID
return gettid();
#else
return syscall(__NR_gettid);
}
#endif
}
static void procattr_thread_destructor(void __attribute__((unused)) *unused)
{
@ -94,7 +96,7 @@ static int openattr(pid_t pid, const char *attr, int flags)
if (fd >= 0 || errno != ENOENT)
goto out;
free(path);
tid = gettid();
tid = selinux_gettid();
rc = asprintf(&path, "/proc/self/task/%d/attr/%s", tid, attr);
} else {
errno = EINVAL;