diff options
Diffstat (limited to 'StdLib/LibC/Uefi/SysCalls.c')
| -rw-r--r-- | StdLib/LibC/Uefi/SysCalls.c | 43 |
1 files changed, 42 insertions, 1 deletions
diff --git a/StdLib/LibC/Uefi/SysCalls.c b/StdLib/LibC/Uefi/SysCalls.c index ebae38f3fb..5576938f8e 100644 --- a/StdLib/LibC/Uefi/SysCalls.c +++ b/StdLib/LibC/Uefi/SysCalls.c @@ -1,7 +1,7 @@ /** @file
EFI versions of NetBSD system calls.
- Copyright (c) 2010 - 2011, Intel Corporation. All rights reserved.<BR>
+ Copyright (c) 2010 - 2012, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials are licensed and made available under
the terms and conditions of the BSD License that accompanies this distribution.
The full text of the license may be found at
@@ -557,16 +557,38 @@ mkdir (const char *path, __mode_t perms) }
/** Open a file.
+ The open() function establishes the connection between a file and a file
+ descriptor. It creates an open file description that refers to a file
+ and a file descriptor that refers to that open file description. The file
+ descriptor is used by other I/O functions to refer to that file.
+
+ The open() function returns a file descriptor for the named file that is
+ the lowest file descriptor not currently open for that process. The open
+ file description is new, and therefore the file descriptor shall not
+ share it with any other process in the system.
+
+ The file offset used to mark the current position within the file is set
+ to the beginning of the file.
The EFI ShellOpenFileByName() function is used to perform the low-level
file open operation. The primary task of open() is to translate from the
flags used in the <stdio.h> environment to those used by the EFI function.
+ The file status flags and file access modes of the open file description
+ are set according to the value of oflags.
+
+ Values for oflags are constructed by a bitwise-inclusive OR of flags from
+ the following list, defined in <fcntl.h>. Applications shall specify
+ exactly one of { O_RDONLY, O_RDWR, O_WRONLY } in the value of oflags.
+ Any combination of { O_NONBLOCK, O_APPEND, O_CREAT, O_TRUNC, O_EXCL } may
+ also be specified in oflags.
+
The only valid flag combinations for ShellOpenFileByName() are:
- Read
- Read/Write
- Create/Read/Write
+ Values for mode specify the access permissions for newly created files.
The mode value is saved in the FD to indicate permissions for further operations.
O_RDONLY -- flags = EFI_FILE_MODE_READ -- this is always done
@@ -578,6 +600,25 @@ mkdir (const char *path, __mode_t perms) O_CREAT -- flags |= EFI_FILE_MODE_CREATE
O_TRUNC -- delete first then create new
O_EXCL -- if O_CREAT is also set, open will fail if the file already exists.
+
+ @param[in] Path The path argument points to a pathname naming the
+ object to be opened.
+ @param[in] oflags File status flags and file access modes of the
+ open file description.
+ @param[in] mode File access permission bits as defined in
+ <sys/stat.h>.
+
+ @return Upon successful completion, open() opens the file and returns
+ a non-negative integer representing the lowest numbered
+ unused file descriptor. Otherwise, open returns -1 and sets
+ errno to indicate the error. If a negative value is
+ returned, no files are created or modified.
+
+ @retval EMFILE No file descriptors available -- Max number already open.
+ @retval EINVAL Bad value specified for oflags or mode.
+ @retval ENOMEM Failure allocating memory for internal buffers.
+ @retval EEXIST File exists and open attempted with (O_EXCL | O_CREAT) set.
+ @retval EIO UEFI failure. Check value in EFIerrno.
**/
int
open(
|