libs/libc/unistd: add getpass function

Add getpass function to pass tlpi example:
https://man7.org/tlpi/code/online/dist/users_groups/check_password.c.html

Signed-off-by: chenzhijia <chenzhijia@xiaomi.com>

Author: chenzhijia

include/unistd.h

@@ -469,6 +469,8 @@ int     syncfs(int fd);
 int     profil(FAR unsigned short *buf, size_t bufsiz,
                size_t offset, unsigned int scale);
 
+FAR char *getpass(FAR const char *prompt);
+
 #if CONFIG_FORTIFY_SOURCE > 0
 fortify_function(getcwd) FAR char *getcwd(FAR char *buf,
                                           size_t size)

libs/libc/libc.csv

@@ -105,6 +105,7 @@
 "getoptindp","unistd.h","","FAR int *"
 "getoptoptp","unistd.h","","FAR int *"
 "getpriority","sys/resource.h","","int","int","id_t"
+"getpass","unistd.h","","FAR const char *"
 "getpwnam_r","pwd.h","","int","FAR const char *","FAR struct passwd *","FAR char *","size_t","FAR struct passwd **"
 "getpwuid_r","pwd.h","","int","uid_t","FAR struct passwd *","FAR char *","size_t","FAR struct passwd **"
 "getrandom","sys/random.h","!defined(CONFIG_BUILD_KERNEL)","ssize_t","FAR void *","size_t","unsigned int"

libs/libc/unistd/CMakeLists.txt

@@ -64,7 +64,8 @@ set(SRCS
     lib_getpgrp.c
     lib_getpgid.c
     lib_lockf.c
-    lib_flock.c)
+    lib_flock.c
+    lib_getpass.c)
 
 if(NOT CONFIG_SCHED_USER_IDENTITY)
   list(

libs/libc/unistd/Make.defs

@@ -32,7 +32,7 @@ CSRCS += lib_setrlimit.c lib_getrlimit.c lib_setpriority.c lib_getpriority.c
 CSRCS += lib_futimes.c lib_lutimes.c lib_gethostname.c lib_sethostname.c
 CSRCS += lib_fchownat.c lib_linkat.c lib_readlinkat.c lib_symlinkat.c
 CSRCS += lib_unlinkat.c lib_usleep.c lib_getpgrp.c lib_getpgid.c
-CSRCS += lib_lockf.c lib_flock.c
+CSRCS += lib_lockf.c lib_flock.c lib_getpass.c
 
 ifneq ($(CONFIG_SCHED_USER_IDENTITY),y)
 CSRCS += lib_setuid.c lib_setgid.c lib_getuid.c lib_getgid.c

libs/libc/unistd/lib_getpass.c

@@ -0,0 +1,96 @@
+/****************************************************************************
+ * libs/libc/unistd/lib_getpass.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 <stdio.h>
+#include <termios.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static char g_password[128];
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR char *getpass(FAR const char *prompt)
+{
+  struct termios s;
+  struct termios t;
+  ssize_t total_bytes_read = 0;
+  ssize_t bytes_read;
+  int fd;
+
+  if ((fd = open("/dev/console", O_RDONLY | O_NOCTTY)) < 0)
+    {
+      fd = STDIN_FILENO;
+    }
+
+  tcgetattr(fd, &t);
+  s = t;
+  t.c_lflag &= ~(ECHO | ISIG);
+  t.c_lflag |= ICANON;
+  t.c_iflag &= ~(INLCR | IGNCR);
+  t.c_iflag |= ICRNL;
+  tcsetattr(fd, TCSAFLUSH, &t);
+  tcdrain(fd);
+
+  if (write(STDERR_FILENO, prompt, strlen(prompt)) != strlen(prompt))
+    {
+      return 0;
+    }
+
+  while ((bytes_read = read(fd, g_password + total_bytes_read,
+                            sizeof(g_password) - total_bytes_read)) > 0)
+    {
+      if (bytes_read > 0 && g_password[total_bytes_read] == '\n')
+        {
+            break;
+        }
+
+      total_bytes_read += bytes_read;
+    }
+
+  if (total_bytes_read >= 0)
+    {
+      if (total_bytes_read > 0 && g_password[total_bytes_read - 1] == '\n')
+        {
+          total_bytes_read--;
+        }
+
+      g_password[total_bytes_read] = 0;
+    }
+
+  tcsetattr(fd, TCSAFLUSH, &s);
+
+  if (fd > STDERR_FILENO)
+    {
+      close(fd);
+    }
+
+  return g_password;
+}