libc/stdio: Make gets/gets_s work without CONFIG_FILE_STREAM

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

libs/libc/libc.h

@@ -97,6 +97,11 @@ ssize_t lib_fwrite(FAR const void *ptr, size_t count, FAR FILE *stream);
 
 ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream);
 
+/* Defined in lib_libgets.c */
+
+FAR char *lib_dgets(FAR char *buf, size_t buflen, int fd,
+                    bool keepnl, bool consume);
+
 /* Defined in lib_libfgets.c */
 
 FAR char *lib_fgets(FAR char *buf, size_t buflen, FILE *stream,

libs/libc/stdio/Make.defs

@@ -25,6 +25,7 @@ CSRCS += lib_fileno.c lib_printf.c lib_sprintf.c lib_asprintf.c
 CSRCS += lib_snprintf.c lib_libsprintf.c lib_vsprintf.c lib_vasprintf.c
 CSRCS += lib_vsnprintf.c lib_dprintf.c lib_vdprintf.c lib_vprintf.c
 CSRCS += lib_perror.c lib_putchar.c lib_getchar.c lib_puts.c
+CSRCS += lib_gets_s.c lib_gets.c lib_libdgets.c
 CSRCS += lib_sscanf.c lib_vsscanf.c lib_libvscanf.c lib_libvsprintf.c
 CSRCS += lib_remove.c lib_tempnam.c lib_tmpnam.c lib_ultoa_invert.c
 CSRCS += lib_renameat.c
@@ -39,7 +40,7 @@ ifeq ($(CONFIG_FILE_STREAM),y)
 CSRCS += lib_fopen.c lib_freopen.c lib_fclose.c lib_fread.c lib_libfread.c
 CSRCS += lib_fseek.c lib_fseeko.c lib_ftell.c lib_ftello.c lib_fsetpos.c
 CSRCS += lib_getdelim.c lib_fgetpos.c lib_getc.c lib_fgetc.c
-CSRCS += lib_fgets.c lib_gets_s.c lib_gets.c lib_libfgets.c lib_fwrite.c
+CSRCS += lib_fgets.c lib_libfgets.c lib_fwrite.c
 CSRCS += lib_libfwrite.c lib_fflush.c lib_libflushall.c lib_libfflush.c
 CSRCS += lib_rdflush.c lib_wrflush.c lib_putc.c lib_fputc.c
 CSRCS += lib_fputs.c lib_ungetc.c lib_fprintf.c lib_vfprintf.c

libs/libc/stdio/lib_gets.c

@@ -26,6 +26,7 @@
 
 #include <stdint.h>
 #include <stdio.h>
+#include <unistd.h>
 
 #include "libc.h"
 
@@ -58,5 +59,9 @@ FAR char *gets(FAR char *s)
 {
   /* Let lib_fgets() do the heavy lifting */
 
+#ifdef CONFIG_FILE_STREAM
   return lib_fgets(s, SIZE_MAX, stdin, false, false);
+#else
+  return lib_dgets(s, SIZE_MAX, STDIN_FILENO, false, false);
+#endif
 }

libs/libc/stdio/lib_gets_s.c

@@ -26,6 +26,7 @@
 
 #include <stdio.h>
 #include <stdint.h>
+#include <unistd.h>
 
 #include "libc.h"
 
@@ -69,5 +70,9 @@ FAR char *gets_s(FAR char *s, rsize_t n)
 
   /* Then let lib_fgets() do the heavy lifting */
 
+#ifdef CONFIG_FILE_STREAM
   return lib_fgets(s, n, stdin, false, true);
+#else
+  return lib_dgets(s, n, STDIN_FILENO, false, true);
+#endif
 }

libs/libc/stdio/lib_libdgets.c

@@ -0,0 +1,207 @@
+/****************************************************************************
+ * libs/libc/stdio/lib_libdgets.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 <nuttx/config.h>
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "libc.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int dgetc(int fd)
+{
+  unsigned char c;
+  return read(fd, &c, 1) == 1 ? c : EOF;
+}
+
+/****************************************************************************
+ * Name: consume_eol
+ *
+ * Description:
+ *   If 'consume' is true, then consume_eol() will read and discard bytes
+ *   from 'fd' until an EOF or a newline encountered or until a read
+ *   error occurs.
+ *
+ ****************************************************************************/
+
+static void consume_eol(int fd, bool consume)
+{
+  if (consume)
+    {
+      int ch;
+
+      do
+        {
+          ch = dgetc(fd);
+        }
+      while (ch != EOF && ch != '\n');
+    }
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: lib_dgets
+ *
+ * Description:
+ *   lib_dgets() implements the core logic for both gets() and gets_s().
+ *   lib_dgets() reads in at most one less than 'buflen' characters from
+ *   fd and stores them into the buffer pointed to by 'buf'. Reading
+ *   stops after an EOF or a newline encountered or after a read error
+ *   occurs.
+ *
+ *   If a newline is read, it is stored into the buffer only if 'keepnl' is
+ *   set true.  A null terminator is always stored after the last character
+ *   in the buffer.
+ *
+ *   If 'buflen'-1 bytes were read into 'buf' without encountering an EOF
+ *   or newline then the following behavior depends on the value of
+ *   'consume':  If consume is true, then lib_dgets() will continue reading
+ *   bytes and discarding them until an EOF or a newline encountered or
+ *   until a read error occurs.  Otherwise, lib_dgets() returns with the
+ *   remaining of the incoming stream buffer.
+ *
+ ****************************************************************************/
+
+FAR char *lib_dgets(FAR char *buf, size_t buflen, int fd,
+                    bool keepnl, bool consume)
+{
+  size_t nch = 0;
+
+  /* Sanity checks */
+
+  if (!buf || fd < 0)
+    {
+      return NULL;
+    }
+
+  /* Make sure that we have a buffer and space for at least one character */
+
+  if (buflen < 1)
+    {
+      consume_eol(fd, consume);
+      return NULL;
+    }
+
+  /* Make sure that we have space for something in addition to the NUL
+   * terminator.
+   */
+
+  if (buflen < 2)
+    {
+      *buf = '\0';
+      consume_eol(fd, consume);
+      return buf;
+    }
+
+  /* Read characters until we have a full line. On each the loop we must
+   * be assured that there are two free bytes in the line buffer:  One for
+   * the next character and one for the null terminator.
+   */
+
+  for (; ; )
+    {
+      /* Get the next character */
+
+      int ch = dgetc(fd);
+
+      /* Check for end-of-line.  This is tricky only in that some
+       * environments may return CR as end-of-line, others LF, and
+       * others both.
+       */
+
+      if (ch == '\n')
+        {
+          /* Convert \r\n to \n */
+
+          if (nch > 0 && buf[nch - 1] == '\r')
+            {
+              --nch;
+            }
+
+          if (keepnl)
+            {
+              /* Store newline is stored in the buffer */
+
+              buf[nch++] = '\n';
+            }
+
+          /* Terminate the string */
+
+          buf[nch] = '\0';
+          return buf;
+        }
+
+      /* Check for end-of-file */
+
+      else if (ch == EOF)
+        {
+          /* End of file with no data? */
+
+          if (nch == 0)
+            {
+              /* Yes.. return NULL as the end of file mark */
+
+              return NULL;
+            }
+          else
+            {
+              /* No, terminate the accumulated string */
+
+              buf[nch] = '\0';
+              return buf;
+            }
+        }
+
+      /* Otherwise, put the character in the line buffer */
+
+      else
+        {
+          buf[nch++] = ch;
+
+          /* Check if there is room for another character and the line's
+           * NUL terminator.  If not then we have to end the line now,
+           * perhaps consuming any data up to the end-of-line.
+           */
+
+          if (nch + 1 >= buflen)
+            {
+              buf[nch] = '\0';
+              consume_eol(fd, consume);
+              return buf;
+            }
+        }
+    }
+}