interpreters/python: use NuttX readline for TTY input

include/system/readline.h

@@ -42,6 +42,11 @@
 #  undef CONFIG_READLINE_TABCOMPLETION
 #endif
 
+/* readline_fd_ex() options */
+
+#define READLINE_CTRL_D_EOF      (1 << 0)
+#define READLINE_RETURN_ON_EINTR (1 << 1)
+
 /* Make sure that the are valid values for all tab-completion settings */
 
 #ifdef CONFIG_READLINE_TABCOMPLETION
@@ -176,6 +181,19 @@ FAR const struct extmatch_vtable_s *
 
 ssize_t readline_fd(FAR char *buf, int buflen, int infd, int outfd);
 
+/****************************************************************************
+ * Name: readline_fd_ex
+ *
+ *   readline_fd_ex() extends readline_fd() with caller-selected options.
+ *   READLINE_CTRL_D_EOF makes Ctrl-D return EOF when the line is empty.
+ *   READLINE_RETURN_ON_EINTR makes an interrupted input read return -EINTR
+ *   instead of being retried.
+ *
+ ****************************************************************************/
+
+ssize_t readline_fd_ex(FAR char *buf, int buflen, int infd, int outfd,
+                       unsigned int options);
+
 /****************************************************************************
  * Name: readline_stream
  *

interpreters/python/python_wrapper.c

@@ -45,6 +45,10 @@
 
 #include <nuttx/drivers/ramdisk.h>
 
+#ifdef CONFIG_SYSTEM_READLINE
+#  include <system/readline.h>
+#endif
+
 #include "romfs_cpython_modules.h"
 
 #include "Python.h"
@@ -80,6 +84,17 @@
 #define MKMOUNT_DEVNAME(m) "/dev/ram" STR_RAMDEVNO(m)
 #define MOUNT_DEVNAME      MKMOUNT_DEVNAME(CONFIG_CPYTHON_ROMFS_RAMDEVNO)
 
+#ifdef CONFIG_SYSTEM_READLINE
+#  if CONFIG_LINE_MAX > 2
+#    define PYTHON_READLINE_BUFSIZE CONFIG_LINE_MAX
+#  else
+#    define PYTHON_READLINE_BUFSIZE 2
+#  endif
+
+#  define PYTHON_READLINE_OPTIONS \
+     (READLINE_CTRL_D_EOF | READLINE_RETURN_ON_EINTR)
+#endif
+
 /****************************************************************************
  * Private Types
  ****************************************************************************/
@@ -92,6 +107,103 @@
  * Private Functions
  ****************************************************************************/
 
+#ifdef CONFIG_SYSTEM_READLINE
+/****************************************************************************
+ * Name: python_readline
+ *
+ * Description:
+ *   Read an interactive line with the NuttX line editor.  CPython calls
+ *   this hook only for a TTY attached to the main interpreter, leaving its
+ *   standard fgets-based reader in place for redirected input and
+ *   subinterpreters.
+ *
+ ****************************************************************************/
+
+static char *python_readline(FILE *sys_stdin, FILE *sys_stdout,
+                             const char *prompt)
+{
+#if defined(CONFIG_READLINE_TABCOMPLETION) || defined(CONFIG_READLINE_EDIT)
+  FAR const char *oldprompt;
+#endif
+  FAR char *line;
+  FAR char *tmp;
+  size_t linesize;
+  size_t used;
+  ssize_t nread;
+
+  fflush(sys_stdout);
+
+  if (prompt != NULL)
+    {
+      fputs(prompt, stderr);
+    }
+
+  fflush(stderr);
+
+  linesize = PYTHON_READLINE_BUFSIZE;
+  line = PyMem_RawMalloc(linesize);
+  if (line == NULL)
+    {
+      return NULL;
+    }
+
+  used = 0;
+
+#if defined(CONFIG_READLINE_TABCOMPLETION) || defined(CONFIG_READLINE_EDIT)
+  oldprompt = readline_prompt(prompt);
+#endif
+
+  for (; ; )
+    {
+      nread = readline_fd_ex(line + used, PYTHON_READLINE_BUFSIZE,
+                             fileno(sys_stdin), fileno(sys_stdout),
+                             PYTHON_READLINE_OPTIONS);
+      if (nread == -EINTR)
+        {
+          PyMem_RawFree(line);
+          line = NULL;
+          break;
+        }
+
+      if (nread == EOF)
+        {
+          line[used] = '\0';
+          break;
+        }
+
+      used += nread;
+      if (used > 0 && line[used - 1] == '\n')
+        {
+          break;
+        }
+
+      if (used > SIZE_MAX - PYTHON_READLINE_BUFSIZE)
+        {
+          PyMem_RawFree(line);
+          line = NULL;
+          break;
+        }
+
+      linesize = used + PYTHON_READLINE_BUFSIZE;
+      tmp = PyMem_RawRealloc(line, linesize);
+      if (tmp == NULL)
+        {
+          PyMem_RawFree(line);
+          line = NULL;
+          break;
+        }
+
+      line = tmp;
+    }
+
+#if defined(CONFIG_READLINE_TABCOMPLETION) || defined(CONFIG_READLINE_EDIT)
+  readline_prompt(oldprompt);
+#endif
+
+  return line;
+}
+#endif
+
 /****************************************************************************
  * Name: check_and_mount_romfs
  *
@@ -194,6 +306,10 @@
 
   _pyruntime_early_init();
 
+#ifdef CONFIG_SYSTEM_READLINE
+  PyOS_ReadlineFunctionPointer = python_readline;
+#endif
+
   setenv("PYTHONHOME", "/usr/local", 1);
 
   setenv("PYTHON_BASIC_REPL", "1", 1);

system/readline/readline.h

@@ -84,6 +84,6 @@ struct rl_common_s
  ****************************************************************************/
 
 ssize_t readline_common(FAR struct rl_common_s *vtbl,
-                        FAR char *buf, int buflen);
+                        FAR char *buf, int buflen, unsigned int options);
 
 #endif /* __APPS_SYSTEM_READLINE_READLINE_H */

system/readline/readline_common.c

@@ -49,12 +49,13 @@
 #  define RL_CMDHIST_LINELEN    CONFIG_READLINE_CMD_HISTORY_LINELEN
 #endif
 
+#define CTRL_D  4   /* ^D - EOF or delete at cursor */
+
 #ifdef CONFIG_READLINE_EDIT_EMACS
-/* Emacs-style control key codes */
+/* Additional Emacs-style control key codes */
 
 #  define CTRL_A  1   /* ^A - Home */
 #  define CTRL_B  2   /* ^B - Left */
-#  define CTRL_D  4   /* ^D - Delete at cursor */
 #  define CTRL_E  5   /* ^E - End */
 #  define CTRL_F  6   /* ^F - Right */
 #  define CTRL_K  11  /* ^K - Kill to end of line */
@@ -849,7 +850,7 @@ FAR const struct extmatch_vtable_s *
  ****************************************************************************/
 
 ssize_t readline_common(FAR struct rl_common_s *vtbl, FAR char *buf,
-                        int buflen)
+                        int buflen, unsigned int options)
 {
   int escape;
   int nch;
@@ -1440,6 +1441,14 @@ ssize_t readline_common(FAR struct rl_common_s *vtbl, FAR char *buf,
           return submit_line(buf, nch);
         }
 
+      /* Some callers use the conventional empty-line Ctrl-D as EOF. */
+
+      else if (ch == CTRL_D && (options & READLINE_CTRL_D_EOF) != 0 &&
+               nch == 0)
+        {
+          return EOF;
+        }
+
       /* Emacs-style control keys */
 
 #ifdef CONFIG_READLINE_EDIT_EMACS

system/readline/readline_fd.c

@@ -42,9 +42,11 @@
 struct readline_s
 {
   struct rl_common_s vtbl;
-  int infd;
+  unsigned int       options;
+  int                infd;
+  int                errcode;
 #ifdef CONFIG_READLINE_ECHO
-  int outfd;
+  int                outfd;
 #endif
 };
 
@@ -92,7 +94,13 @@ static int readline_getc(FAR struct rl_common_s *vtbl)
            */
 
           int errcode = errno;
-          if (errcode != EINTR)
+          if (errcode == EINTR &&
+              (priv->options & READLINE_RETURN_ON_EINTR) != 0)
+            {
+              priv->errcode = errcode;
+              return EOF;
+            }
+          else if (errcode != EINTR)
             {
               /* Return EOF on any errors that we cannot handle */
 
@@ -218,6 +226,16 @@ static void readline_write(FAR struct rl_common_s *vtbl,
  ****************************************************************************/
 
 ssize_t readline_fd(FAR char *buf, int buflen, int infd, int outfd)
+{
+  return readline_fd_ex(buf, buflen, infd, outfd, 0);
+}
+
+/****************************************************************************
+ * Name: readline_fd_ex
+ ****************************************************************************/
+
+ssize_t readline_fd_ex(FAR char *buf, int buflen, int infd, int outfd,
+                       unsigned int options)
 {
   UNUSED(outfd);
 
@@ -240,6 +258,8 @@ ssize_t readline_fd(FAR char *buf, int buflen, int infd, int outfd)
 
   vtbl.vtbl.rl_getc  = readline_getc;
   vtbl.infd          = infd;
+  vtbl.options       = options;
+  vtbl.errcode       = 0;
 
 #ifdef CONFIG_READLINE_ECHO
   vtbl.vtbl.rl_putc  = readline_putc;
@@ -249,12 +269,17 @@ ssize_t readline_fd(FAR char *buf, int buflen, int infd, int outfd)
 
   /* The let the common readline logic do the work */
 
-  ret = readline_common(&vtbl.vtbl, buf, buflen);
+  ret = readline_common(&vtbl.vtbl, buf, buflen, options);
 
   if (isatty(infd) && (cfg.c_lflag & ICANON))
     {
       tcsetattr(infd, TCSANOW, &cfg);
     }
 
+  if (vtbl.errcode != 0)
+    {
+      ret = -vtbl.errcode;
+    }
+
   return ret;
 }