libc: Implement ttyname and ttyname_r

Note: this patch can get file path from root pseudo file handle,
but a general infrastructure is setup for other file system too.

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
Change-Id: I86cd79ebb741f2f43fdd398bb7498c40687d949b

libs/libc/termios/Make.defs

@@ -27,6 +27,7 @@ ifeq ($(CONFIG_SERIAL_TERMIOS),y)
 
 CSRCS += lib_cfspeed.c lib_cfmakeraw.c lib_isatty.c lib_tcflush.c
 CSRCS += lib_tcflow.c lib_tcgetattr.c lib_tcsetattr.c
+CSRCS += lib_ttyname.c lib_ttynamer.c
 
 # Add the termios directory to the build
 

libs/libc/termios/lib_ttyname.c

@@ -0,0 +1,69 @@
+/****************************************************************************
+ * libs/libc/termios/lib_ttyname.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <errno.h>
+#include <limits.h>
+#include <unistd.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: ttyname
+ *
+ * Description:
+ *   The ttyname() function shall return a pointer to a string containing
+ *   a null-terminated pathname of the terminal associated with file
+ *   descriptor fildes. The application shall not modify the string returned.
+ *   The returned pointer might be invalidated or the string content might
+ *   be overwritten by a subsequent call to ttyname(). The returned pointer
+ *   and the string content might also be invalidated if the calling thread
+ *   is terminated.
+ *
+ * Input Parameters:
+ *   fd - The 'fd' argument is an open file descriptor associated with
+ *        a terminal.
+ *
+ * Returned Value:
+ *   Upon successful completion, ttyname() shall return a pointer to
+ *   a string. Otherwise, a null pointer shall be returned and errno
+ *   set to indicate the error.
+ *
+ ****************************************************************************/
+
+FAR char *ttyname(int fd)
+{
+  static char name[TTY_NAME_MAX];
+  int ret;
+
+  ret = ttyname_r(fd, name, TTY_NAME_MAX);
+  if (ret != 0)
+    {
+      set_errno(ret);
+      return NULL;
+    }
+
+  return name;
+}

libs/libc/termios/lib_ttynamer.c

@@ -0,0 +1,85 @@
+/****************************************************************************
+ * libs/libc/termios/lib_ttynamer.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: ttyname_r
+ *
+ * Description:
+ *   The ttyname_r() function shall store the null-terminated pathname of
+ *   the terminal associated with the file descriptor fildes in the
+ *   character array referenced by name. The array is namesize characters
+ *   long and should have space for the name and the terminating null
+ *   character. The maximum length of the terminal name shall be
+ *   {TTY_NAME_MAX}.
+ *
+ * Input Parameters:
+ *   fd - The 'fd' argument is an open file descriptor associated with
+ *        a terminal.
+ *   buf - Caller provided buffer to hold tty name.
+ *   buflen - The size of the caller-provided buffer.
+ *
+ * Returned Value:
+ *   If successful, the ttyname_r() function shall return zero.
+ *   Otherwise, an error number shall be returned to indicate the error.
+ *
+ ****************************************************************************/
+
+int ttyname_r(int fd, FAR char *buf, size_t buflen)
+{
+  if (!isatty(fd))
+    {
+      return ENOTTY;
+    }
+
+  if (buflen >= TTY_NAME_MAX)
+    {
+      return fcntl(fd, F_GETPATH, buf) < 0 ? get_errno() : 0;
+    }
+  else
+    {
+      char name[TTY_NAME_MAX];
+
+      if (fcntl(fd, F_GETPATH, name) < 0)
+        {
+          return get_errno();
+        }
+
+      if (strlen(name) >= buflen)
+        {
+          return ERANGE;
+        }
+
+      strcpy(buf, name);
+      return OK;
+    }
+}