[MINIOS PATCH v3 1/5] introduce get_file_from_fd()

[Juergen Gross <jgross@xxxxxxxx>]

Exporting the files[] array especially for components outside the
mini-os source tree is limiting the ability to change any file handling
in mini-os.

Introduce a new function get_file_from_fd() to return the struct file
pointer (or NULL) for a given file descriptor.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
---
V3:
- use ARRAY_SIZE() for boundary check (Andrew Cooper)
---
 include/lib.h | 1 +
 lib/sys.c     | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/include/lib.h b/include/lib.h
index 91364ba7..7a0546bd 100644
--- a/include/lib.h
+++ b/include/lib.h
@@ -198,6 +198,7 @@ struct file {
 
 extern struct file files[];
 
+struct file *get_file_from_fd(int fd);
 int alloc_fd(enum fd_type type);
 void close_all_files(void);
 extern struct thread *main_thread;
diff --git a/lib/sys.c b/lib/sys.c
index 6f2b026d..9a03875c 100644
--- a/lib/sys.c
+++ b/lib/sys.c
@@ -98,6 +98,14 @@ struct file files[NOFILE] = {
     { .type = FTYPE_CONSOLE }, /* stderr */
 };
 
+struct file *get_file_from_fd(int fd)
+{
+    if ( fd < 0 || fd >= ARRAY_SIZE(files) )
+        return NULL;
+
+    return (files[fd].type == FTYPE_NONE) ? NULL : files + fd;
+}
+
 DECLARE_WAIT_QUEUE_HEAD(event_queue);
 
 int alloc_fd(enum fd_type type)
-- 
2.26.2