H5Fopen
(
const char *name
,
unsigned flags
,
hid_t fapl_id
)
H5Fopen
is the primary function for accessing
existing HDF5 files.
This function opens the named file in the specified access mode
and with the specified access property list.
Note that H5Fopen
does not create a file
if it does not already exist;
see H5Fcreate
.
The name
parameter specifies the name of the file
to be opened.
The fapl_id
parameter specifies the file access
property list. Use of H5P_DEFAULT
specifies that
default I/O access properties are to be used
The flags
parameter specifies whether the file
will be opened in read-write or read-only mode,
H5F_ACC_RDWR
or H5F_ACC_RDONLY
,
respectively.
More complex behaviors of file access are controlled
through the file-access property list.
The return value is a file identifier for the open file;
this file identifier should be closed by calling
H5Fclose
when it is no longer needed.
Special cases — Multiple opens:
A file can often be opened with a new H5Fopen
call without closing an already-open identifier established
in a previous H5Fopen
or H5Fcreate
call. Each such H5Fopen
call will return a
unique identifier and the file can be accessed through any
of these identifiers as long as the identifier remains valid.
In such multiply-opened cases,
the open calls must use the same flags
argument
and the file access property lists must use the same
file close degree property setting
(see the external link discussion below and
H5Pset_fclose_degree
).
In some cases, such as files on a local Unix file system, the HDF5 library can detect that a file is multiply opened and will maintain coherent access among the file identifiers.
But in many other cases, such as parallel file systems or networked file systems, it is not always possible to detect multiple opens of the same physical file. In such cases, HDF5 will treat the file identifiers as though they are accessing different files and will be unable to maintain coherent access. Errors are likely to result in these cases. While unlikely, the HDF5 library may not be able to detect, and thus report, such errors.
It is generally recommended that applications avoid multiple opens of the same file.
Special restriction on multiple opens of a file first
opened by means of an external link:
When an external link is followed, the external file is always
opened with the weak file close degree property setting,
H5F_CLOSE_WEAK
(see
H5Lcreate_external
and
H5Pset_fclose_degree
).
If the file is reopened with H5Fopen
while
it remains held open from such an external link call,
the file access proeprty list used in the open call must include
the file close degree setting H5F_CLOSE_WEAK
or the open will fail.
const char *name |
IN: Name of the file to be created. |
unsigned flags |
IN: File access flags. Allowable values are:
An additional flag, |
hid_t fapl_id |
IN: Identifier for the file access properties list.
If parallel file access is desired, this is a collective
call according to the communicator stored in the
fapl_id .
Use H5P_DEFAULT for default file access
properties. |
SUBROUTINE h5fopen_f(name, access_flags, file_id, hdferr, & access_prp) IMPLICIT NONE CHARACTER(LEN=*), INTENT(IN) :: name ! Name of the file INTEGER, INTENT(IN) :: access_flag ! File access flags ! Possible values are: ! H5F_ACC_RDWR_F ! H5F_ACC_RDONLY_F INTEGER(HID_T), INTENT(OUT) :: file_id ! File identifier INTEGER, INTENT(OUT) :: hdferr ! Error code ! 0 on success and -1 on failure INTEGER(HID_T), OPTIONAL, INTENT(IN) :: access_prp ! File access property list ! identifier END SUBROUTINE h5fopen_f