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

include/fcntl.h

@@ -95,6 +95,7 @@
 #define F_SETLKW    12 /* Like F_SETLK, but wait for lock to become available */
 #define F_SETOWN    13 /* Set pid that will receive SIGIO and SIGURG signals for fd */
 #define F_SETSIG    14 /* Set the signal to be sent */
+#define F_GETPATH   15 /* Get the path of the file descriptor(BSD/macOS) */
 
 /* For posix fcntl() and lockf() */
 

include/limits.h

@@ -201,6 +201,7 @@
 #define MAX_CANON      _POSIX_MAX_CANON
 #define MAX_INPUT      _POSIX_MAX_INPUT
 #define NAME_MAX       _POSIX_NAME_MAX
+#define TTY_NAME_MAX   _POSIX_NAME_MAX
 #define NGROUPS_MAX    _POSIX_NGROUPS_MAX
 #define OPEN_MAX       _POSIX_OPEN_MAX
 #define PATH_MAX       _POSIX_PATH_MAX

include/nuttx/fs/ioctl.h

@@ -180,6 +180,9 @@
 #define FIONCLEX        _FIOC(0x000e)     /* IN:  None
                                            * OUT: None
                                            */
+#define FIOC_FILEPATH   _FIOC(0x000f)     /* IN:  FAR char *(length >= PATH_MAX)
+                                           * OUT: The full file path
+                                           */
 
 /* NuttX file system ioctl definitions **************************************/
 

include/unistd.h

@@ -322,6 +322,9 @@ int     ftruncate(int fd, off_t length);
 /* Check if a file descriptor corresponds to a terminal I/O file */
 
 int     isatty(int fd);
+
+FAR char *ttyname(int fd);
+int       ttyname_r(int fd, FAR char *buf, size_t buflen);
 #endif
 
 /* Memory management */