libc/stdio: Preallocate the stdin, stdout and stderr

to handle the uninitialized stdin/stdout/stderr gracefully
report here:
https://github.com/apache/incubator-nuttx/issues/2203

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

fs/vfs/fs_fdopen.c

@@ -178,36 +178,61 @@ int fs_fdopen(int fd, int oflags, FAR struct tcb_s *tcb,
       goto errout;
     }
 
+  /* Get the stream list from the TCB */
+
+#ifdef CONFIG_MM_KERNEL_HEAP
+  slist = tcb->group->tg_streamlist;
+#else
+  slist = &tcb->group->tg_streamlist;
+#endif
+
   /* Allocate FILE structure */
 
-#ifdef CONFIG_STDIO_DISABLE_BUFFERING
+  if (fd >= 3)
-  stream = group_zalloc(tcb->group, sizeof(FILE));
-  if (stream == NULL)
     {
-      ret = -ENOMEM;
+      stream = group_zalloc(tcb->group, sizeof(FILE));
-      goto errout;
+      if (stream == NULL)
+        {
+          ret = -ENOMEM;
+          goto errout;
+        }
+
+      /* Add FILE structure to the stream list */
+
+      ret = nxsem_wait(&slist->sl_sem);
+      if (ret < 0)
+        {
+          group_free(tcb->group, stream);
+          goto errout;
+        }
+
+      if (slist->sl_tail)
+        {
+          slist->sl_tail->fs_next = stream;
+          slist->sl_tail = stream;
+        }
+      else
+        {
+          slist->sl_head = stream;
+          slist->sl_tail = stream;
+        }
+
+      nxsem_post(&slist->sl_sem);
+
+      /* Initialize the semaphore the manages access to the buffer */
+
+      lib_sem_initialize(stream);
     }
-#else
+  else
-  stream = group_malloc(tcb->group, sizeof(FILE) +
-                        CONFIG_STDIO_BUFFER_SIZE);
-  if (stream == NULL)
     {
-      ret = -ENOMEM;
+      stream = &slist->sl_std[fd];
-      goto errout;
     }
 
-  /* Zero the structure */
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
-
-  memset(stream, 0, sizeof(FILE));
-
-  /* Initialize the semaphore the manages access to the buffer */
-
-  lib_sem_initialize(stream);
-
 #if CONFIG_STDIO_BUFFER_SIZE > 0
   /* Set up pointers */
 
-  stream->fs_bufstart = (FAR unsigned char *)(stream + 1);
+  stream->fs_bufstart = stream->fs_buffer;
   stream->fs_bufend   = &stream->fs_bufstart[CONFIG_STDIO_BUFFER_SIZE];
   stream->fs_bufpos   = stream->fs_bufstart;
   stream->fs_bufread  = stream->fs_bufstart;
@@ -229,34 +254,6 @@ int fs_fdopen(int fd, int oflags, FAR struct tcb_s *tcb,
   stream->fs_fd       = fd;
   stream->fs_oflags   = oflags;
 
-  /* Get the stream list from the TCB */
-
-#ifdef CONFIG_MM_KERNEL_HEAP
-  slist = tcb->group->tg_streamlist;
-#else
-  slist = &tcb->group->tg_streamlist;
-#endif
-
-  /* Add FILE structure to the stream list */
-
-  ret = nxsem_wait(&slist->sl_sem);
-  if (ret < 0)
-    {
-      goto errout_with_mem;
-    }
-
-  if (slist->sl_tail)
-    {
-      slist->sl_tail->fs_next = stream;
-      slist->sl_tail = stream;
-    }
-  else
-    {
-      slist->sl_head = stream;
-      slist->sl_tail = stream;
-    }
-
-  nxsem_post(&slist->sl_sem);
   if (filep != NULL)
     {
       *filep = stream;
@@ -264,9 +261,6 @@ int fs_fdopen(int fd, int oflags, FAR struct tcb_s *tcb,
 
   return OK;
 
-errout_with_mem:
-  group_free(tcb->group, stream);
-
 errout:
   if (filep != NULL)
     {

include/nuttx/fs/fs.h

@@ -469,6 +469,9 @@ struct file_struct
   FAR unsigned char      *fs_bufend;    /* Pointer to 1 past end of buffer */
   FAR unsigned char      *fs_bufpos;    /* Current position in buffer */
   FAR unsigned char      *fs_bufread;   /* Pointer to 1 past last buffered read char. */
+#  if CONFIG_STDIO_BUFFER_SIZE > 0
+  unsigned char           fs_buffer[CONFIG_STDIO_BUFFER_SIZE];
+#  endif
 #endif
   uint16_t                fs_oflags;    /* Open mode flags */
   uint8_t                 fs_flags;     /* Stream flags */
@@ -481,6 +484,7 @@ struct file_struct
 struct streamlist
 {
   sem_t                   sl_sem;   /* For thread safety */
+  struct file_struct      sl_std[3];
   FAR struct file_struct *sl_head;
   FAR struct file_struct *sl_tail;
 };

include/stdio.h

@@ -78,9 +78,9 @@
 
 /* The first three _iob entries are reserved for standard I/O */
 
-#define stdin      (nxsched_get_streams()->sl_head)
+#define stdin      (&nxsched_get_streams()->sl_std[0])
-#define stdout     (nxsched_get_streams()->sl_head->fs_next)
+#define stdout     (&nxsched_get_streams()->sl_std[1])
-#define stderr     (nxsched_get_streams()->sl_head->fs_next->fs_next)
+#define stderr     (&nxsched_get_streams()->sl_std[2])
 
 /* Path to the directory where temporary files can be created */
 

libs/libc/misc/lib_stream.c

@@ -85,6 +85,15 @@ void lib_stream_initialize(FAR struct task_group_s *group)
   _SEM_INIT(&list->sl_sem, 0, 1);
   list->sl_head = NULL;
   list->sl_tail = NULL;
+
+  /* Initialize stdin, stdout and stderr stream */
+
+  list->sl_std[0].fs_fd = -1;
+  lib_sem_initialize(&list->sl_std[0]);
+  list->sl_std[1].fs_fd = -1;
+  lib_sem_initialize(&list->sl_std[1]);
+  list->sl_std[2].fs_fd = -1;
+  lib_sem_initialize(&list->sl_std[2]);
 }
 #endif /* CONFIG_FILE_STREAM */
 
@@ -147,6 +156,14 @@ void lib_stream_release(FAR struct task_group_s *group)
           group_free(group, stream);
         }
     }
+
+  /* Destroy stdin, stdout and stderr stream */
+
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+  _SEM_DESTROY(&list->sl_std[0].fs_sem);
+  _SEM_DESTROY(&list->sl_std[1].fs_sem);
+  _SEM_DESTROY(&list->sl_std[2].fs_sem);
+#endif
 }
 
 #endif /* CONFIG_FILE_STREAM */