[Msan] Add ptsname, ptsname_r interceptors

[MaskRay]

compiler-rt/test/sanitizer_common/TestCases/Linux/ptsname.c

5

600 in glibc

12

Consider supporting the case that posix_openpt return -1 (the effective user cannot create a pseudo terminal)

13

The coding standard prefers char *

[vitalybuka]

addressed @MaskRay comments

[vitalybuka]

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

4876

@eugenis implementation uses static buffer which can result in data race if called from multiple threads
I made this consistent with ttyname, but I am no sure if we maybe want to apply tsan to this buffer.
In this patch I'll keep COMMON_INTERCEPTOR_INITIALIZE_RANGE, but maybe we want to switch this behavior later?

4885

BTW on some platforms including glibc ptsname is implemented with ptsname_r

compiler-rt/test/sanitizer_common/TestCases/Linux/ptsname.c

5

switched to getpt

[eugenis]

LGTM

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

4876

This is exactly what INITIALIZE_RANGE is for - it's a write from MSan PoV, but not for TSan.

4885

Does it break anything? I hope it does not use ptsname_r to initialize the common static buffer - that would be a data race.

[MaskRay]

(glibc uses __ptsname_internal to implement ptsname, so technically for the lldb issue ptsname_r does not need to be intercepted)

I still slightly prefer posix_openpt because it works on FreeBSD automatically. FreeBSD does not have openpt

[vitalybuka]

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

4885

Nevermind, both use "__ptsname_r", not ptsname_r, so ptsname is not going to call ptsname_r inteceptor

[vitalybuka]

switch to posix_openpt

[vitalybuka]

In D88547#2304571, @MaskRay wrote:

(glibc uses __ptsname_internal to implement ptsname, so technically for the lldb issue ptsname_r does not need to be intercepted)

I still slightly prefer posix_openpt because it works on FreeBSD automatically. FreeBSD does not have openpt

done

[MaskRay]

compiler-rt/test/sanitizer_common/TestCases/Linux/ptsname.c

21

If you want to be nicer to FreeBSD... it does not have ptsname_r

I'll not push this argument too hard because this directory is Linux :)

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

INTERCEPTOR(char *, tmpnam_r, char *s) {
   if (res && s) COMMON_INTERCEPTOR_WRITE_RANGE(ctx, s, REAL(strlen)(s) + 1);
   return res;
 }
 #define INIT_TMPNAM_R COMMON_INTERCEPT_FUNCTION(tmpnam_r);
 #else
 #define INIT_TMPNAM_R
 #endif
 
+#if SANITIZER_INTERCEPT_PTSNAME
+INTERCEPTOR(char *, ptsname, int fd) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, ptsname, fd);
+  char *res = REAL(ptsname)(fd);
+  if (res != nullptr)
+    COMMON_INTERCEPTOR_INITIALIZE_RANGE(res, REAL(strlen)(res) + 1);
+  return res;
+}
+#define INIT_PTSNAME COMMON_INTERCEPT_FUNCTION(ptsname);
+#else
+#define INIT_PTSNAME
+#endif
+
+#if SANITIZER_INTERCEPT_PTSNAME_R
+INTERCEPTOR(int, ptsname_r, int fd, char *name, SIZE_T namesize) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, ptsname_r, fd, name, namesize);
+  int res = REAL(ptsname_r)(fd, name, namesize);
+  if (res == 0)
+    COMMON_INTERCEPTOR_WRITE_RANGE(ctx, name, REAL(strlen)(name) + 1);
+  return res;
+}
+#define INIT_PTSNAME_R COMMON_INTERCEPT_FUNCTION(ptsname_r);
+#else
+#define INIT_PTSNAME_R
+#endif
+
 #if SANITIZER_INTERCEPT_TTYNAME
 INTERCEPTOR(char *, ttyname, int fd) {
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, ttyname, fd);
   char *res = REAL(ttyname)(fd);
   if (res != nullptr)
     COMMON_INTERCEPTOR_INITIALIZE_RANGE(res, REAL(strlen)(res) + 1);
   return res;
#endif
   INIT_PTHREAD_MUTEXATTR_GETROBUST_NP;
   INIT_PTHREAD_RWLOCKATTR_GETPSHARED;
   INIT_PTHREAD_RWLOCKATTR_GETKIND_NP;
   INIT_PTHREAD_CONDATTR_GETPSHARED;
   INIT_PTHREAD_CONDATTR_GETCLOCK;
   INIT_PTHREAD_BARRIERATTR_GETPSHARED;
   INIT_TMPNAM;
   INIT_TMPNAM_R;
+  INIT_PTSNAME;
+  INIT_PTSNAME_R;
   INIT_TTYNAME;
   INIT_TTYNAME_R;
   INIT_TEMPNAM;
   INIT_PTHREAD_SETNAME_NP;
   INIT_PTHREAD_GETNAME_NP;
   INIT_SINCOS;
   INIT_REMQUO;
   INIT_REMQUOL;

compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h

#define SANITIZER_INTERCEPT_PTHREAD_CONDATTR_GETPSHARED \
   (SI_POSIX && !SI_NETBSD && !SI_OPENBSD)
 #define SANITIZER_INTERCEPT_PTHREAD_CONDATTR_GETCLOCK \
   (SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_PTHREAD_BARRIERATTR_GETPSHARED \
   (SI_LINUX_NOT_ANDROID && !SI_NETBSD && !SI_OPENBSD)
 #define SANITIZER_INTERCEPT_THR_EXIT SI_FREEBSD
 #define SANITIZER_INTERCEPT_TMPNAM SI_POSIX
 #define SANITIZER_INTERCEPT_TMPNAM_R SI_LINUX_NOT_ANDROID || SI_SOLARIS
+#define SANITIZER_INTERCEPT_PTSNAME SI_LINUX
+#define SANITIZER_INTERCEPT_PTSNAME_R SI_LINUX
 #define SANITIZER_INTERCEPT_TTYNAME SI_POSIX
 #define SANITIZER_INTERCEPT_TTYNAME_R SI_POSIX
 #define SANITIZER_INTERCEPT_TEMPNAM SI_POSIX
 #define SANITIZER_INTERCEPT_SINCOS SI_LINUX || SI_SOLARIS
 #define SANITIZER_INTERCEPT_REMQUO SI_POSIX
 #define SANITIZER_INTERCEPT_REMQUOL (SI_POSIX && !SI_NETBSD)
 #define SANITIZER_INTERCEPT_LGAMMA SI_POSIX
 #define SANITIZER_INTERCEPT_LGAMMAL (SI_POSIX && !SI_NETBSD)

compiler-rt/test/sanitizer_common/TestCases/Linux/ptsname.c

+// RUN: %clang %s -o %t && %run %t
+
+#define _GNU_SOURCE
+#define _XOPEN_SOURCE 600
+
+#include <assert.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+int main() {
+  int pt = posix_openpt(O_NOCTTY);
+  if (pt == -1)
+    return 0;
+  char *s = ptsname(pt);
+  assert(s);
+  assert(strstr(s, "/dev"));
+
+  char buff[1000] = {};
+  int r = ptsname_r(pt, buff, sizeof(buff));
+  assert(!r);
+  assert(strstr(buff, "/dev"));
+
+  close(pt);
+  return 0;
+}