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HDF5
1.15.0.f73da83
API Reference
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HDF5
1.15.0.f73da83
API Reference
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Use the functions in this module to manage HDF5 groups.
| Create | Read |
|---|---|
15 {
16 __label__ fail_group, fail_prop, fail_lcpl, fail_file;
17 hid_t file, lcpl, group;
18 char fname[] = "g1.h5";
19 char path[] = "/αυτή/είναι/μια/νέα/ομάδα";
20
22 ret_val = EXIT_FAILURE;
23 goto fail_file;
24 }
25
27 ret_val = EXIT_FAILURE;
28 goto fail_lcpl;
29 }
30 // ensure that intermediate groups are created automatically
32 ret_val = EXIT_FAILURE;
33 goto fail_prop;
34 }
35 // use UTF-8 encoding for link names
37 ret_val = EXIT_FAILURE;
38 goto fail_prop;
39 }
40 // create five groups
42 ret_val = EXIT_FAILURE;
43 goto fail_group;
44 }
45
46 H5Gclose(group);
47fail_group:
48fail_prop:
49 H5Pclose(lcpl);
50fail_lcpl:
51 H5Fclose(file);
52fail_file:;
53 }
| 57 {
58 __label__ fail_file;
59 char fname[] = "g1.h5";
60 char path[] = "/αυτή/είναι";
61 hid_t file;
62 H5G_info_t info;
63
65 ret_val = EXIT_FAILURE;
66 goto fail_file;
67 }
68 // open one of the intermediate groups
70 ret_val = EXIT_FAILURE;
71 goto fail_info;
72 }
73
77 printf("Compact storage\n");
78 break;
80 printf("Compact storage\n");
81 break;
83 printf("Symbol table\n");
84 break;
85 default:
86 printf("UFO\n");
87 break;
88 }
89
90fail_info:
91 H5Fclose(file);
92fail_file:;
93 }
|
| Update | Delete |
97 {
98 __label__ fail_group, fail_prop, fail_lcpl, fail_file;
99 hid_t file, lcpl, group;
100 char fname[] = "g1.h5";
101 char path[] = "/αυτή/είναι/μια/άλλη/νέα/ομάδα";
102
104 ret_val = EXIT_FAILURE;
105 goto fail_file;
106 }
107
109 ret_val = EXIT_FAILURE;
110 goto fail_lcpl;
111 }
112 // ensure that intermediate groups are created automatically
114 ret_val = EXIT_FAILURE;
115 goto fail_prop;
116 }
117 // use UTF-8 encoding for link names
119 ret_val = EXIT_FAILURE;
120 goto fail_prop;
121 }
122 // create an anonymous group
124 ret_val = EXIT_FAILURE;
125 goto fail_group;
126 }
127 // link the new group to existing the group at "/αυτή/είναι/μια"
129 ret_val = EXIT_FAILURE;
130 }
131
132 H5Gclose(group);
133fail_group:
134fail_prop:
135 H5Pclose(lcpl);
136fail_lcpl:
137 H5Fclose(file);
138fail_file:;
139 }
| 143 {
144 __label__ fail_info, fail_object, fail_file;
145 hid_t file, obj;
146 char fname[] = "g1.h5";
147 char path[] = "/αυτή/είναι/μια/άλλη/νέα/ομάδα";
148 char delete_path[] = "/αυτή/είναι/μια";
149 H5O_info_t info;
150
152 ret_val = EXIT_FAILURE;
153 goto fail_file;
154 }
155
156 // open a "leaf" group as object
158 ret_val = EXIT_FAILURE;
159 goto fail_object;
160 }
161 // delete the link to an intermediate group on the path to the leaf
163 ret_val = EXIT_FAILURE;
164 }
165 // link deletion will propagate along hard links along all paths
166 // reachable from the intermediate group and cause reference counts to
167 // be decremented, freeing the objects if the count reaches 0
169 ret_val = EXIT_FAILURE;
170 goto fail_info;
171 }
172
173 printf("Leaf reference count: %d\n", info.rc);
174
175fail_info:
176 H5Oclose(obj);
177fail_object:
178 H5Fclose(file);
179fail_file:;
180 }
|
Groups in HDF5: A group associates names with objects and provides a mechanism for mapping a name to an object. Since all objects appear in at least one group (with the possible exception of the root object) and since objects can have names in more than one group, the set of all objects in an HDF5 file is a directed graph. The internal nodes (nodes with an out-degree greater than zero) must be groups, while the leaf nodes (nodes with an out-degree zero) are either empty groups or objects of some other type. Exactly one object in every non-empty file is the root object. The root object always has a positive in-degree because it is pointed to by the file superblock.
Locating objects in the HDF5 file hierarchy: An object name consists of one or more components separated from one another by slashes. An absolute name begins with a slash, and the object is located by looking for the first component in the root object, then looking for the second component in the first object, etc., until the entire name is traversed. A relative name does not begin with a slash, and the traversal begins at the location specified by the create or access function.
Group implementations in HDF5: The original HDF5 group implementation provided a single-indexed structure for link storage. A new group implementation, in HDF5 Release 1.8.0, enables more efficient compact storage for very small groups, improved link indexing for large groups, and other advanced features.
The original group structure and the newer structures are not directly interoperable. By default, a group will be created in the original indexed format. An existing group can be changed to a compact-or-indexed format if the need arises; there is no capability to change back. As stated above, once in the compact-or-indexed format, a group can switch between compact and indexed as needed.
Groups will be initially created in the compact-or-indexed format only when one or more of the following conditions is met:
An existing group, currently in the original indexed format, will be converted to the compact-or-indexed format upon the occurrence of any of the following events:
The compact-or-indexed format offers performance improvements that will be most notable at the extremes, i.e., in groups with zero members and in groups with tens of thousands of members. But measurable differences may sometimes appear at a threshold as low as eight group members. Since these performance thresholds and criteria differ from application to application, tunable settings are provided to govern the switch between the compact and indexed formats (see H5Pset_link_phase_change()). Optimal thresholds will depend on the application and the operating environment.
Future versions of HDF5 will retain the ability to create, read, write, and manipulate all groups stored in either the original indexed format or the compact-or-indexed format.
Macros | |
| #define | H5Gcreate H5Gcreate2 |
| #define | H5Gopen H5Gopen2 |
Functions | |
| hid_t | H5Gcreate2 (hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id, hid_t gapl_id) |
| Creates a new group and links it into the file. | |
| hid_t | H5Gcreate_anon (hid_t loc_id, hid_t gcpl_id, hid_t gapl_id) |
| Creates a new empty group without linking it into the file structure. | |
| hid_t | H5Gopen2 (hid_t loc_id, const char *name, hid_t gapl_id) |
| Opens an existing group in a file. | |
| hid_t | H5Gget_create_plist (hid_t group_id) |
| Gets a group creation property list identifier. | |
| herr_t | H5Gget_info (hid_t loc_id, H5G_info_t *ginfo) |
| Retrieves information about a group. | |
| herr_t | H5Gget_info_by_name (hid_t loc_id, const char *name, H5G_info_t *ginfo, hid_t lapl_id) |
| Retrieves information about a group by its name. | |
| herr_t | H5Gget_info_by_idx (hid_t loc_id, const char *group_name, H5_index_t idx_type, H5_iter_order_t order, hsize_t n, H5G_info_t *ginfo, hid_t lapl_id) |
| Retrieves information about a group, according to the group's position within an index. | |
| herr_t | H5Gflush (hid_t group_id) |
| Flushes all buffers associated with a group to disk. | |
| herr_t | H5Grefresh (hid_t group_id) |
| Refreshes all buffers associated with a group. | |
| herr_t | H5Gclose (hid_t group_id) |
| Closes the specified group. | |
| hid_t | H5Gcreate1 (hid_t loc_id, const char *name, size_t size_hint) |
| Creates a new group and links it into the file. | |
| hid_t | H5Gopen1 (hid_t loc_id, const char *name) |
| Opens an existing group for modification and returns a group identifier for that group. | |
| herr_t | H5Glink (hid_t cur_loc_id, H5L_type_t type, const char *cur_name, const char *new_name) |
Creates a link of the specified type from new_name to cur_name. | |
| herr_t | H5Glink2 (hid_t cur_loc_id, const char *cur_name, H5L_type_t type, hid_t new_loc_id, const char *new_name) |
Creates a link of the specified type from cur_name to new_name. | |
| herr_t | H5Gmove (hid_t src_loc_id, const char *src_name, const char *dst_name) |
| Renames an object within an HDF5 file. | |
| herr_t | H5Gmove2 (hid_t src_loc_id, const char *src_name, hid_t dst_loc_id, const char *dst_name) |
| Renames an object within an HDF5 file. | |
| herr_t | H5Gunlink (hid_t loc_id, const char *name) |
| Removes the link to an object from a group. | |
| herr_t | H5Gget_linkval (hid_t loc_id, const char *name, size_t size, char *buf) |
| Returns the name of the object that the symbolic link points to. | |
| herr_t | H5Gset_comment (hid_t loc_id, const char *name, const char *comment) |
| Sets comment for specified object. | |
| int | H5Gget_comment (hid_t loc_id, const char *name, size_t bufsize, char *buf) |
| Retrieves comment for specified object. | |
| herr_t | H5Giterate (hid_t loc_id, const char *name, int *idx, H5G_iterate_t op, void *op_data) |
| Iterates over the entries of a group invoking a callback for each entry encountered. | |
| herr_t | H5Gget_num_objs (hid_t loc_id, hsize_t *num_objs) |
| Returns number of objects in the group specified by its identifier. | |
| herr_t | H5Gget_objinfo (hid_t loc_id, const char *name, hbool_t follow_link, H5G_stat_t *statbuf) |
| Returns information about an object. | |
| ssize_t | H5Gget_objname_by_idx (hid_t loc_id, hsize_t idx, char *name, size_t size) |
| Returns the name of an object specified by an index. | |
| H5G_obj_t | H5Gget_objtype_by_idx (hid_t loc_id, hsize_t idx) |
| Returns the type of an object specified by an index. | |
| #define H5Gcreate H5Gcreate2 |
H5Gcreate() is a macro that is mapped to either H5Gcreate1() or H5Gcreate2().
| #define H5Gopen H5Gopen2 |
H5Gopen() is a macro that is mapped to either H5Gopen1() or H5Gopen2().
Closes the specified group.
| [in] | group_id | Group identifier |
H5Gclose() releases resources used by a group that was opened by H5Gcreate() or H5Gopen(). After closing a group, group_id cannot be used again until another H5Gcreate() or H5Gopen() is called on it.
Failure to release a group with this call will result in resource leaks.
Creates a new group and links it into the file.
| [in] | loc_id | Location identifier. The identifier may be that of a file, group, dataset, named datatype, or attribute. |
| [in] | name | Name of the group to create |
| [in] | size_hint | The number of bytes to reserve for the names that will appear in the group |
H5Gcreate1() creates a new group with the specified name at the specified location, loc_id. loc_id may be a file, group, dataset, named datatype or attribute. If an attribute, dataset, or named datatype is specified for loc_id then the group will be created at the location where the attribute, dataset, or named datatype is attached. The name, name, must not already be taken by some other object and all parent groups must already exist.
name can be a relative path based at loc_id or an absolute path from the root of the file. Use of this function requires that any intermediate groups specified in the path already exist.
The length of a group name, or of the name of any object within a group, is not limited.
size_hint is a hint for the number of bytes to reserve to store the names which will be eventually added to the new group. This value must be between 0 and UINT32_MAX (inclusive). If this parameter is zero, a default value will be used.
The return value is a group identifier for the open group. This group identifier should be closed by calling H5Gclose() when it is no longer needed.
See H5Gcreate_anon() for a discussion of the differences between H5Gcreate1() and H5Gcreate_anon().
Creates a new group and links it into the file.
| [in] | loc_id | Location identifier. The identifier may be that of a file, group, dataset, named datatype, or attribute. |
| [in] | name | Name of the group to create |
| [in] | lcpl_id | Link creation property list identifier |
| [in] | gcpl_id | Group creation property list identifier |
| [in] | gapl_id | Group access property list identifier |
H5Gcreate2() creates a new group in a file. After a group has been created, links to datasets and to other groups can be added.
The loc_id and name parameters specify where the group is located. loc_id may be a file, group, dataset, named datatype or attribute in the file. If an attribute, dataset, or named datatype is specified for loc_id then the group will be created at the location where the attribute, dataset, or named datatype is attached. name is the link to the group; name may be either an absolute path in the file (the links from the root group to the new group) or a relative path from loc_id (the link(s) from the group specified by loc_id to the new group).
lcpl_id, gcpl_id, and gapl_id are property list identifiers. These property lists govern how the link to the group is created, how the group is created, and how the group can be accessed in the future, respectively. H5P_DEFAULT can be passed in if the default properties are appropriate for these property lists. Currently, there are no APIs for the group access property list; use H5P_DEFAULT.
The group identifier should be closed by H5Gclose() when access is no longer required to prevent resource leaks.
Creates a new empty group without linking it into the file structure.
| [in] | loc_id | Location identifier. The identifier may be that of a file, group, dataset, named datatype, or attribute. |
| [in] | gcpl_id | Group creation property list identifier |
| [in] | gapl_id | Group access property list identifier |
H5Gcreate_anon() creates a new empty group in the file specified by loc_id. With default settings, H5Gcreate_anon() provides similar functionality to that provided by H5Gcreate1(), with the differences described in the list below.
The new group's creation and access properties are specified in gcpl_id and gapl_id, respectively.
H5Gcreate_anon() returns a new group identifier. This identifier must be linked into the HDF5 file structure with H5Olink() or it will be deleted from the file when the file is closed.
The differences between this function and H5Gcreate1() are as follows:
gcpl_id through a H5Pset_local_heap_size_hint() call.A group created with this function should be closed with H5Gclose() when the group is no longer needed so that resource leaks will not develop.
Flushes all buffers associated with a group to disk.
| [in] | group_id | Group identifier |
H5Gflush() causes all buffers associated with a group to be immediately flushed to the disk without removing the data from the cache.
| int H5Gget_comment | ( | hid_t | loc_id, |
| const char * | name, | ||
| size_t | bufsize, | ||
| char * | buf ) |
Retrieves comment for specified object.
| [in] | loc_id | Location identifier. The identifier may be that of a file, group, dataset, or named datatype. |
| [in] | name | Name of the object whose comment is to be set or reset name must be '.' (dot) if loc_id fully specifies the object for which the comment is to be set. |
| [in] | bufsize | Maximum number of comment characters to be returned in buf. |
| [in] | buf | The comment |
NULL terminator, if successful; the value returned may be larger than bufsize. Otherwise returns a negative value.H5Gget_comment() retrieves the comment for the object specified by loc_id and name. The comment is returned in the buffer buf.
loc_id can specify any object in the file. name can be one of the following:
loc_id /, the file's root group loc_id fully specifies the objectAt most bufsize characters, including a null-terminator, are returned in buf. The returned value is not null-terminated if the comment is longer than the supplied buffer. If the size of the comment is unknown, a preliminary H5Gget_comment() call will return the size of the comment, including space for the null-terminator.
If an object does not have a comment, the empty string is returned in comment.
Gets a group creation property list identifier.
| [in] | group_id | Group identifier |
H5Gget_create_plist() returns an identifier for the group creation property list associated with the group specified by group_id.
The creation property list identifier should be released with H5Pclose() to prevent resource leaks.
| herr_t H5Gget_info | ( | hid_t | loc_id, |
| H5G_info_t * | ginfo ) |
Retrieves information about a group.
| [in] | loc_id | Location identifier. The identifier may be that of a file, group, dataset, named datatype, or attribute. |
| [out] | ginfo | Struct in which group information is returned |
H5Gget_info() retrieves information about the group at location specified by loc_id. The information is returned in the ginfo.
ginfo is an H5G_info_t struct and is defined (in H5Gpublic.h) as follows:
Possible values of storage_type are:
| H5G_STORAGE_TYPE_COMPACT | Compact storage |
| H5G_STORAGE_TYPE_DENSE | Indexed storage |
| H5G_STORAGE_TYPE_SYMBOL_TABLE | Symbol tables, the original HDF5 structure |
| herr_t H5Gget_info_by_idx | ( | hid_t | loc_id, |
| const char * | group_name, | ||
| H5_index_t | idx_type, | ||
| H5_iter_order_t | order, | ||
| hsize_t | n, | ||
| H5G_info_t * | ginfo, | ||
| hid_t | lapl_id ) |
Retrieves information about a group, according to the group's position within an index.
| [in] | loc_id | Location identifier. The identifier may be that of a file, group, dataset, named datatype, or attribute. |
| [in] | group_name | Name of the group to query |
| [in] | idx_type | Transient index identifying object |
| [in] | order | Transient index identifying object |
| [in] | n | Position in the index of the group to query |
| [out] | ginfo | Struct in which group information is returned |
| [in] | lapl_id | Link access property list identifier |
loc_id and group_name specify the group containing the group for which information is sought. The groups in group_name are indexed by idx_type; the group for which information is retrieved is identified in that index by index order, order, and index position, n.
If loc_id specifies the group containing the group for which information is queried, group_name can be a dot (.).
Valid values for index_type are as follows:
| H5_INDEX_NAME | Lexicographic order on name |
| H5_INDEX_CRT_ORDER | Index on creation order |
The order in which the index is to be examined, as specified by order, can be one of the following:
| H5_ITER_INC | Increasing order |
| H5_ITER_DEC | Decreasing order |
| H5_ITER_NATIVE | Fastest available order |
| herr_t H5Gget_info_by_name | ( | hid_t | loc_id, |
| const char * | name, | ||
| H5G_info_t * | ginfo, | ||
| hid_t | lapl_id ) |
Retrieves information about a group by its name.
| [in] | loc_id | Location identifier. The identifier may be that of a file, group, dataset, named datatype, or attribute. |
| [in] | name | Name of the group to query |
| [out] | ginfo | Struct in which group information is returned |
| [in] | lapl_id | Link access property list identifier |
H5Gget_info_by_name() retrieves information about the group name at location specified by loc_id. The information is returned in the ginfo struct.
If loc_id specifies the group for which information is queried, then the group's name can be a dot (.).
ginfo is an H5G_info_t struct and is defined (in H5Gpublic.h) as follows:
Possible values of storage_type are:
| H5G_STORAGE_TYPE_COMPACT | Compact storage |
| H5G_STORAGE_TYPE_DENSE | Indexed storage |
| H5G_STORAGE_TYPE_SYMBOL_TABLE | Symbol tables, the original HDF5 structure |
Returns the name of the object that the symbolic link points to.
| [in] | loc_id | Location identifier. The identifier may be that of a file or group. |
| [in] | name | Symbolic link to the object whose name is to be returned |
| [in] | size | Maximum number of characters of value to be returned |
| [out] | buf | A buffer to hold the name of the object being sought |
H5Gget_linkval() returns up to size characters of the name of the object that the symbolic link name points to.
The parameter loc_id is a file or group identifier.
The parameter name must be a symbolic link pointing to the desired object and must be defined relative to loc_id.
If size is smaller than the size of the returned object name, then the name stored in the buffer value will not be NULL terminated.
This function fails if name is not a symbolic link. The presence of a symbolic link can be tested by passing zero for size and NULL for value.
This function should be used only after H5Lget_info1() (or the deprecated function H5Gget_objinfo()) has been called to verify that name is a symbolic link.
Returns number of objects in the group specified by its identifier.
| [in] | loc_id | Location identifier. The identifier may be that of a file or group. |
| [out] | num_objs | Number of objects in the group |
H5Gget_num_objs() returns number of objects in a group. Group is specified by its identifier loc_id. If a file identifier is passed in, then the number of objects in the root group is returned.
| herr_t H5Gget_objinfo | ( | hid_t | loc_id, |
| const char * | name, | ||
| hbool_t | follow_link, | ||
| H5G_stat_t * | statbuf ) |
Returns information about an object.
| [in] | loc_id | Location identifier. The identifier may be that of a file, group, dataset, or named datatype. |
| [in] | name | Name of the object for which status is being sought |
| [in] | follow_link | Link flag |
| [out] | statbuf | Buffer in which to return information about the object |
H5Gget_objinfo() returns information about the specified object through the statbuf argument.
A file or group identifier, loc_id, and an object name, name, relative to loc_id, are commonly used to specify the object. However, if the object identifier is already known to the application, an alternative approach is to use that identifier, obj_id, in place of loc_id, and a dot (.) in place of name. Thus, the alternative versions of the first portion of an H5Gget_objinfo() call would be as follows:
If the object is a symbolic link and follow_link is zero (0), then the information returned describes the link itself; otherwise the link is followed and the information returned describes the object to which the link points. If follow_link is non-zero but the final symbolic link is dangling (does not point to anything), then an error is returned. The statbuf fields are undefined for an error. The existence of an object can be tested by calling this function with a NULL statbuf.
H5Gget_objinfo() fills in the following data structure (defined in H5Gpublic.h):
where H5O_stat_t (defined in H5Opublic.h) is:
mtime value of 0 (zero).Returns the name of an object specified by an index.
| [in] | loc_id | Location identifier. The identifier may be that of a file or group. |
| [in] | idx | Transient index identifying object |
| [in,out] | name | Pointer to user-provided buffer the object name |
| [in] | size | Name length |
H5Gget_objname_by_idx() returns the name of the object specified by the index idx in the group loc_id.
The group is specified by a group identifier loc_id. If preferred, a file identifier may be passed in loc_id; that file's root group will be assumed.
idx is the transient index used to iterate through the objects in the group. The value of idx is any nonnegative number less than the total number of objects in the group, which is returned by the function H5Gget_num_objs(). Note that this is a transient index; an object may have a different index each time a group is opened.
The object name is returned in the user-specified buffer name.
If the size of the provided buffer name is less or equal the actual object name length, the object name is truncated to max_size - 1 characters.
Note that if the size of the object's name is unknown, a preliminary call to H5Gget_objname_by_idx() with name set to NULL will return the length of the object's name. A second call to H5Gget_objname_by_idx() can then be used to retrieve the actual name.
Returns the type of an object specified by an index.
| [in] | loc_id | Location identifier. The identifier may be that of a file or group. |
| [in] | idx | Transient index identifying object |
H5Gget_objtype_by_idx() returns the type of the object specified by the index idx in the group loc_id.
The group is specified by a group identifier loc_id. If preferred, a file identifier may be passed in loc_id; that file's root group will be assumed.
idx is the transient index used to iterate through the objects in the group. This parameter is described in more detail in the discussion of H5Gget_objname_by_idx().
int to the enumerated type H5G_obj_t. | herr_t H5Giterate | ( | hid_t | loc_id, |
| const char * | name, | ||
| int * | idx, | ||
| H5G_iterate_t | op, | ||
| void * | op_data ) |
Iterates over the entries of a group invoking a callback for each entry encountered.
| [in] | loc_id | Location identifier. The identifier may be that of a file or group. |
| [in] | name | Group over which the iteration is performed |
| [in,out] | idx | Location at which to begin the iteration |
| [in] | op | Operation to be performed on an object at each step of the iteration |
| [in,out] | op_data | Data associated with the operation |
H5Giterate() iterates over the members of name in the file or group specified with loc_id. For each object in the group, the op_data and some additional information, specified below, are passed to the operator function. The iteration begins with the idx object in the group and the next element to be processed by the operator is returned in idx. If idx is NULL, then the iterator starts at the first group member; since no stopping point is returned in this case, the iterator cannot be restarted if one of the calls to its operator returns non-zero. H5Giterate() does not recursively follow links into subgroups of the specified group.
The prototype for H5G_iterate_t is:
The operation receives the group identifier for the group being iterated over, group, the name of the current object within the group, name, and the pointer to the operator data passed into H5Giterate(), op_data.
The return values from an operator are:
H5Giterate() assumes that the membership of the group identified by name remains unchanged through the iteration. If the membership changes during the iteration, the function's behavior is undefined.
H5Giterate() is not recursive. In particular, if a member of name is found to be a group, call it subgroup_a, H5Giterate() does not examine the members of subgroup_a. When recursive iteration is required, the application must handle the recursion, explicitly calling H5Giterate() on discovered subgroups.
| herr_t H5Glink | ( | hid_t | cur_loc_id, |
| H5L_type_t | type, | ||
| const char * | cur_name, | ||
| const char * | new_name ) |
Creates a link of the specified type from new_name to cur_name.
| [in] | cur_loc_id | Location identifier. The identifier may be that of a file or group. |
| [in] | type | Link type |
| [in] | cur_name | Name of the existing object |
| [in] | new_name | New name for the object |
H5Glink() creates a new name for an object that has some current name, possibly one of many names it currently has.
If link_type is H5G_LINK_HARD, then cur_name must specify the name of an existing object and both names are interpreted relative to cur_loc_id, which is either a file identifier or a group identifier.
If link_type is H5G_LINK_SOFT, then cur_name can be anything and is interpreted at lookup time relative to the group which contains the final component of new_name. For instance, if cur_name is ./foo, new_name is ./x/y/bar, and a request is made for ./x/y/bar, then the actual object looked up is ./x/y/./foo.
| herr_t H5Glink2 | ( | hid_t | cur_loc_id, |
| const char * | cur_name, | ||
| H5L_type_t | type, | ||
| hid_t | new_loc_id, | ||
| const char * | new_name ) |
Creates a link of the specified type from cur_name to new_name.
| [in] | cur_loc_id | Location identifier. The identifier may be that of a file or group. |
| [in] | cur_name | Name of the existing object |
| [in] | type | Link type |
| [in] | new_loc_id | Location identifier. The identifier may be that of a file or group. |
| [in] | new_name | New name for the object |
H5Glink2() creates a new name for an object that has some current name, possibly one of many names it currently has.
If link_type is H5G_LINK_HARD, then cur_name must specify the name of an existing object and both names are interpreted relative to cur_loc_id and new_loc_id, respectively, which are either file identifiers or group identifiers.
If link_type is H5G_LINK_SOFT, then cur_name can be anything and is interpreted at lookup time relative to the group which contains the final component of new_name. For instance, if current_name is ./foo, new_name is ./x/y/bar, and a request is made for ./x/y/bar, then the actual object looked up is ./x/y/./foo.
Renames an object within an HDF5 file.
| [in] | src_loc_id | Location identifier. The identifier may be that of a file or group. |
| [in] | src_name | Object's original name |
| [in] | dst_name | Object's new name |
H5Gmove() renames an object within an HDF5 file. The original name, src_name, is unlinked from the group graph and the new name, dst_name, is inserted as an atomic operation. Both names are interpreted relative to loc_id, which is either a file or a group identifier.
| herr_t H5Gmove2 | ( | hid_t | src_loc_id, |
| const char * | src_name, | ||
| hid_t | dst_loc_id, | ||
| const char * | dst_name ) |
Renames an object within an HDF5 file.
| [in] | src_loc_id | Location identifier. The identifier may be that of a file or group. |
| [in] | src_name | Object's original name |
| [in] | dst_loc_id | Location identifier. The identifier may be that of a file or group. |
| [in] | dst_name | Object's new name |
H5Gmove2() renames an object within an HDF5 file. The original name, src_name, is unlinked from the group graph and the new name, dst_name, is inserted as an atomic operation.
src_name and dst_name are interpreted relative to src_loc_id and dst_loc_id, respectively, which are either file or group identifiers.
Opens an existing group for modification and returns a group identifier for that group.
| [in] | loc_id | Location identifier. The identifier may be that of a file, group, dataset, named datatype, or attribute. |
| [in] | name | Name of the group to open |
H5Gopen1() opens an existing group, name, at the location specified by loc_id.
H5Gopen1() returns a group identifier for the group that was opened. This group identifier should be released by calling H5Gclose() when it is no longer needed.
Opens an existing group in a file.
| [in] | loc_id | Location identifier. The identifier may be that of a file, group, dataset, named datatype, or attribute. |
| [in] | name | Name of the group to open |
| [in] | gapl_id | Group access property list identifier |
H5Gopen2() opens an existing group, name, at the location specified by loc_id.
With default settings, H5Gopen2() provides similar functionality to that provided by H5Gopen(). The only difference is that H5Gopen2() can provide a group access property list, gapl_id.
H5Gopen2() returns a group identifier for the group that was opened. This group identifier should be released by H5Gclose() when it is no longer needed to prevent resource leaks.
Refreshes all buffers associated with a group.
| [in] | group_id | Group identifier |
H5Grefresh() causes all buffers associated with a group to be cleared and immediately re-loaded with updated contents from disk.
This function essentially closes the group, evicts all metadata associated with it from the cache, and then reopens the group. The reopened group is automatically re-registered with the same identifier.
Sets comment for specified object.
| [in] | loc_id | Location identifier. The identifier may be that of a file, group, dataset, or named datatype. |
| [in] | name | Name of the object whose comment is to be set or reset name must be '.' (dot) if loc_id fully specifies the object for which the comment is to be set. |
| [in] | comment | The new comment |
H5Gset_comment() sets the comment for the object specified by loc_id and name to comment. Any previously existing comment is overwritten.
loc_id can specify any object in the file. name can be one of the following:
loc_id /, the file's root group loc_id fully specifies the objectIf comment is the empty string or a null pointer, the comment message is removed from the object.
Comments should be relatively short, null-terminated, ASCII strings.
Comments can be attached to any object that has an object header, e.g., datasets, groups, and named datatypes, but not symbolic links.
Removes the link to an object from a group.
| [in] | loc_id | Location identifier. The identifier may be that of a file or group. |
| [in] | name | Name of the object to unlink |
H5Gunlink() removes the object specified by name from the group graph and decrements the link count for the object to which name points. This action eliminates any association between name and the object to which name pointed.
Object headers keep track of how many hard links refer to an object; when the link count reaches zero, the object can be removed from the file. Objects which are open are not removed until all identifiers to the object are closed.
If the link count reaches zero, all file space associated with the object will be released, i.e., identified in memory as freespace. If any object identifier is open for the object, the space will not be released until after the object identifier is closed.
Note that space identified as freespace is available for reuse only as long as the file remains open; once a file has been closed, the HDF5 library loses track of freespace. See “Freespace Management” in the HDF5 User Guide for further details.
1.10.0