diff --git a/libc/Android.mk b/libc/Android.mk
index 0487a8f..15a68b9 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -45,7 +45,6 @@
     bionic/fts.c \
     bionic/gethostname.c \
     bionic/getpriority.c \
-    bionic/getpt.c \
     bionic/if_indextoname.c \
     bionic/if_nametoindex.c \
     bionic/initgroups.c \
@@ -53,8 +52,6 @@
     bionic/isatty.c \
     bionic/memmem.c \
     bionic/pathconf.c \
-    bionic/ptsname.c \
-    bionic/ptsname_r.c \
     bionic/pututline.c \
     bionic/sched_cpualloc.c \
     bionic/sched_cpucount.c \
@@ -63,7 +60,6 @@
     bionic/siginterrupt.c \
     bionic/sigsetmask.c \
     bionic/system_properties_compat.c \
-    bionic/unlockpt.c \
     stdio/snprintf.c\
     stdio/sprintf.c \
 
@@ -175,6 +171,7 @@
     bionic/pthread_setschedparam.cpp \
     bionic/pthread_sigmask.cpp \
     bionic/ptrace.cpp \
+    bionic/pty.cpp \
     bionic/raise.cpp \
     bionic/rand.cpp \
     bionic/readlink.cpp \
diff --git a/libc/bionic/getpt.c b/libc/bionic/getpt.c
deleted file mode 100644
index 8bb5c11..0000000
--- a/libc/bionic/getpt.c
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * Copyright (C) 2008 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *  * Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- *  * Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-#include <unistd.h>
-#include <fcntl.h>
-
-int getpt(void)
-{
-  return open("/dev/ptmx", O_RDWR|O_NOCTTY);
-}
diff --git a/libc/bionic/ptsname.c b/libc/bionic/ptsname.c
deleted file mode 100644
index 24d5d30..0000000
--- a/libc/bionic/ptsname.c
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * Copyright (C) 2008 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *  * Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- *  * Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-#include <stdio.h>
-#include <unistd.h>
-#include <termios.h>
-#include <sys/ioctl.h>
-
-/* not thread-safe */
-char*  ptsname( int fd )
-{
-    unsigned int  pty_num;
-    static char   buff[64];
-
-    if ( ioctl( fd, TIOCGPTN, &pty_num ) != 0 )
-        return NULL;
-
-    snprintf( buff, sizeof(buff), "/dev/pts/%u", pty_num );
-    return buff;
-}
diff --git a/libc/bionic/ptsname_r.c b/libc/bionic/ptsname_r.c
deleted file mode 100644
index 2fa4c3d..0000000
--- a/libc/bionic/ptsname_r.c
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
- * Copyright (C) 2008 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *  * Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- *  * Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-#include <stdio.h>
-#include <unistd.h>
-#include <termios.h>
-#include <sys/ioctl.h>
-#include <errno.h>
-#include <string.h>
-
-int    ptsname_r( int  fd, char*  buf, size_t  buflen)
-{
-    unsigned int  pty_num;
-    char          buff[64];
-    int           len;
-
-    if (buf == NULL) {
-        errno = EINVAL;
-        return -1;
-    }
-
-    if ( ioctl( fd, TIOCGPTN, &pty_num ) != 0 ) {
-        errno = ENOTTY;
-        return -1;
-    }
-
-    len = snprintf( buff, sizeof(buff), "/dev/pts/%u", pty_num );
-    if (len+1 > (int)buflen) {
-        errno = ERANGE;
-        return -1;
-    }
-    memcpy( buf, buff, len+1 );
-    return 0;
-}
diff --git a/libc/bionic/pty.cpp b/libc/bionic/pty.cpp
new file mode 100644
index 0000000..995e006
--- /dev/null
+++ b/libc/bionic/pty.cpp
@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <termios.h>
+#include <unistd.h>
+
+int getpt(void) {
+  return posix_openpt(O_RDWR|O_NOCTTY);
+}
+
+int grantpt(int) {
+  return 0;
+}
+
+int posix_openpt(int flags) {
+  return open("/dev/ptmx", flags);
+}
+
+char* ptsname(int fd) {
+  static char buf[64];
+  return ptsname_r(fd, buf, sizeof(buf)) == 0 ? buf : NULL;
+}
+
+int ptsname_r(int fd, char* buf, size_t len) {
+  if (buf == NULL) {
+    errno = EINVAL;
+    return errno;
+  }
+
+  unsigned int pty_num;
+  if (ioctl(fd, TIOCGPTN, &pty_num) != 0) {
+    errno = ENOTTY;
+    return errno;
+  }
+
+  if (snprintf(buf, len, "/dev/pts/%u", pty_num) >= static_cast<int>(len)) {
+    errno = ERANGE;
+    return errno;
+  }
+
+  return 0;
+}
+
+char* ttyname(int fd) {
+  static char buf[64];
+  return ttyname_r(fd, buf, sizeof(buf)) == 0 ? buf : NULL;
+}
+
+int ttyname_r(int fd, char* buf, size_t len) {
+  if (buf == NULL) {
+    errno = EINVAL;
+    return errno;
+  }
+
+  if (!isatty(fd)) {
+    return errno;
+  }
+
+  char path[64];
+  snprintf(path, sizeof(path), "/proc/self/fd/%d", fd);
+
+  ssize_t count = readlink(path, buf, len);
+  if (count == -1) {
+    return errno;
+  }
+  if (static_cast<size_t>(count) == len) {
+    errno = ERANGE;
+    return errno;
+  }
+  buf[count] = '\0';
+  return 0;
+}
+
+int unlockpt(int fd) {
+  int unlock = 0;
+  return ioctl(fd, TIOCSPTLCK, &unlock);
+}
diff --git a/libc/bionic/stubs.cpp b/libc/bionic/stubs.cpp
index 0937e9c..b1e38be 100644
--- a/libc/bionic/stubs.cpp
+++ b/libc/bionic/stubs.cpp
@@ -444,16 +444,6 @@
   UNIMPLEMENTED;
 }
 
-char* ttyname(int /*fd*/) { // NOLINT: implementing bad function.
-  UNIMPLEMENTED;
-  return NULL;
-}
-
-int ttyname_r(int /*fd*/, char* /*buf*/, size_t /*buflen*/) {
-  UNIMPLEMENTED;
-  return -ERANGE;
-}
-
 char* getusershell() {
   UNIMPLEMENTED;
   return NULL;
diff --git a/libc/bionic/unlockpt.c b/libc/bionic/unlockpt.c
deleted file mode 100644
index 998b7a3..0000000
--- a/libc/bionic/unlockpt.c
+++ /dev/null
@@ -1,36 +0,0 @@
-/*
- * Copyright (C) 2008 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *  * Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- *  * Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-#include <unistd.h>
-#include <sys/ioctl.h>
-
-int  unlockpt( int  fd )
-{
-    int  unlock = 0;
-
-    return ioctl( fd, TIOCSPTLCK, &unlock );
-}
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index 195765a..857d631 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -120,18 +120,12 @@
 char* setstate(char*);
 void srandom(unsigned int);
 
-/* Basic PTY functions.  These only work if devpts is mounted! */
-
-extern int    unlockpt(int);
-extern char*  ptsname(int);
-extern int    ptsname_r(int, char*, size_t);
-extern int    getpt(void);
-
-static __inline__ int grantpt(int __fd __attribute((unused)))
-{
-  (void)__fd;
-  return 0;     /* devpts does this all for us! */
-}
+int getpt(void);
+int grantpt(int);
+int posix_openpt(int);
+char* ptsname(int) __warnattr("ptsname is not thread-safe; use ptsname_r instead");
+int ptsname_r(int, char*, size_t);
+int unlockpt(int);
 
 typedef struct {
     int  quot;
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index 12e6257..82c53e8 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -170,7 +170,7 @@
 extern int optind, opterr, optopt;
 
 extern int isatty(int);
-extern char* ttyname(int);
+extern char* ttyname(int) __warnattr("ttyname is not thread-safe; use ttyname_r instead");
 extern int ttyname_r(int, char*, size_t);
 
 extern int  acct(const char*  filepath);