/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Copyright by The HDF Group. * * Copyright by the Board of Trustees of the University of Illinois. * * All rights reserved. * * * * This file is part of HDF5. The full HDF5 copyright notice, including * * terms governing use, modification, and redistribution, is contained in * * the COPYING file, which can be found at the root of the source code * * distribution tree, or in https://www.hdfgroup.org/licenses. * * If you do not have access to either file, you may request a copy from * * help@hdfgroup.org. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /*------------------------------------------------------------------------- * * Created: H5Lpublic.h * Dec 1 2005 * James Laird * * Purpose: Public declarations for the H5L package (links) * *------------------------------------------------------------------------- */ #ifndef H5Lpublic_H #define H5Lpublic_H /* Public headers needed by this file */ #include "H5public.h" /* Generic Functions */ #include "H5Ipublic.h" /* IDs */ #include "H5Tpublic.h" /* Datatypes */ /*****************/ /* Public Macros */ /*****************/ /** * \brief Maximum length of a link's name * * The maximum length of a link's name is encoded in a 32-bit unsigned integer. */ #define H5L_MAX_LINK_NAME_LEN UINT32_MAX /** * \brief Macro to indicate operation occurs on same location */ #define H5L_SAME_LOC 0 /* (hid_t) */ /** * \brief Current version of the H5L_class_t struct */ #define H5L_LINK_CLASS_T_VERS 1 /** * \brief Previous version of the H5L_class_t struct */ #define H5L_LINK_CLASS_T_VERS_0 0 #ifdef __cplusplus extern "C" { #endif /*******************/ /* Public Typedefs */ /*******************/ /** * \brief Link class types. * * Values less than 64 are reserved for the HDF5 library's internal use. Values * 64 to 255 are for "user-defined" link class types; these types are defined * by HDF5 but their behavior can be overridden by users. Users who want to * create new classes of links should contact the HDF5 development team at * mailto:help@hdfgroup.org. These values can never change because they appear * in HDF5 files. */ typedef enum { H5L_TYPE_ERROR = (-1), /**< Invalid link type id */ H5L_TYPE_HARD = 0, /**< Hard link id */ H5L_TYPE_SOFT = 1, /**< Soft link id */ H5L_TYPE_EXTERNAL = 64, /**< External link id */ H5L_TYPE_MAX = 255 /**< Maximum link type id */ } H5L_type_t; /** * \brief Maximum value link value for "built-in" link types */ #define H5L_TYPE_BUILTIN_MAX H5L_TYPE_SOFT /** * \brief Link ids at or above this value are "user-defined" link types. */ #define H5L_TYPE_UD_MIN H5L_TYPE_EXTERNAL /** * \brief Information struct for links */ //! typedef struct { H5L_type_t type; /**< Type of link */ hbool_t corder_valid; /**< Indicate if creation order is valid */ int64_t corder; /**< Creation order */ H5T_cset_t cset; /**< Character set of link name */ union { haddr_t address; /**< Address hard link points to */ size_t val_size; /**< Size of a soft link or user-defined link value */ } u; } H5L_info_t; //! /* The H5L_class_t struct can be used to override the behavior of a * "user-defined" link class. Users should populate the struct with callback * functions defined below. */ /* Callback prototypes for user-defined links */ /** * \brief Link creation callback */ typedef herr_t (*H5L_create_func_t)(const char *link_name, hid_t loc_group, const void *lnkdata, size_t lnkdata_size, hid_t lcpl_id); /** * \brief Callback for link move */ typedef herr_t (*H5L_move_func_t)(const char *new_name, hid_t new_loc, const void *lnkdata, size_t lnkdata_size); /** * \brief Callback for link copy */ typedef herr_t (*H5L_copy_func_t)(const char *new_name, hid_t new_loc, const void *lnkdata, size_t lnkdata_size); typedef hid_t (*H5L_traverse_0_func_t)(const char *link_name, hid_t cur_group, const void *lnkdata, size_t lnkdata_size, hid_t lapl_id); /** * \brief Callback during link traversal */ typedef hid_t (*H5L_traverse_func_t)(const char *link_name, hid_t cur_group, const void *lnkdata, size_t lnkdata_size, hid_t lapl_id, hid_t dxpl_id); /** * \brief Callback for link deletion */ typedef herr_t (*H5L_delete_func_t)(const char *link_name, hid_t file, const void *lnkdata, size_t lnkdata_size); /** * \brief Callback for querying the link. * * Returns the size of the buffer needed. */ typedef ssize_t (*H5L_query_func_t)(const char *link_name, const void *lnkdata, size_t lnkdata_size, void *buf /*out*/, size_t buf_size); /* User-defined link types */ typedef struct { int version; /* Version number of this struct */ H5L_type_t id; /* Link type ID */ const char * comment; /* Comment for debugging */ H5L_create_func_t create_func; /* Callback during link creation */ H5L_move_func_t move_func; /* Callback after moving link */ H5L_copy_func_t copy_func; /* Callback after copying link */ H5L_traverse_0_func_t trav_func; /* Callback during link traversal */ H5L_delete_func_t del_func; /* Callback for link deletion */ H5L_query_func_t query_func; /* Callback for queries */ } H5L_class_0_t; /** * \brief Link prototype * * The H5L_class_t struct can be used to override the behavior of a * "user-defined" link class. Users should populate the struct with callback * functions defined elsewhere. */ //! typedef struct { int version; /**< Version number of this struct */ H5L_type_t id; /**< Link type ID */ const char * comment; /**< Comment for debugging */ H5L_create_func_t create_func; /**< Callback during link creation */ H5L_move_func_t move_func; /**< Callback after moving link */ H5L_copy_func_t copy_func; /**< Callback after copying link */ H5L_traverse_func_t trav_func; /**< Callback during link traversal */ H5L_delete_func_t del_func; /**< Callback for link deletion */ H5L_query_func_t query_func; /**< Callback for queries */ } H5L_class_t; //! /** * \brief Prototype for H5Literate(), H5Literate_by_name() operator */ //! typedef herr_t (*H5L_iterate_t)(hid_t group, const char *name, const H5L_info_t *info, void *op_data); //! /** * \brief Callback for external link traversal */ typedef herr_t (*H5L_elink_traverse_t)(const char *parent_file_name, const char *parent_group_name, const char *child_file_name, const char *child_object_name, unsigned *acc_flags, hid_t fapl_id, void *op_data); /********************/ /* Public Variables */ /********************/ /*********************/ /* Public Prototypes */ /*********************/ /** * \ingroup H5L * * \brief Moves a link within an HDF5 file * * \fgdta_loc_id{src_loc} * \param[in] src_name Original link name * \fgdta_loc_id{dst_loc} * \param[in] dst_name New link name * \lcpl_id * \lapl_id * * \return \herr_t * * \details H5Lmove() moves a link within an HDF5 file. The original link, * \p src_name, is removed from \p src_loc and the new link, * \p dst_name, is inserted at dst_loc. This change is * accomplished as an atomic operation. * * \p src_loc and \p src_name identify the original link. * \p src_loc is the original location identifier; \p src_name is * the path to the link and is interpreted relative to \p src_loc. * * \p dst_loc and \p dst_name identify the new link. \p dst_loc is * either a file or group identifier; \p dst_name is the path to * the link and is interpreted relative to \p dst_loc. * * \p lcpl_id and \p lapl_id are the link creation and link access * property lists, respectively, associated with the new link, * \p dst_name. * * Through these property lists, several properties are available to * govern the behavior of H5Lmove(). The property controlling creation * of missing intermediate groups is set in the link creation property * list with H5Pset_create_intermediate_group(); H5Lmove() ignores any * other properties in the link creation property list. Properties * controlling character encoding, link traversals, and external link * prefixes are set in the link access property list with * H5Pset_char_encoding(), H5Pset_nlinks(), and H5Pset_elink_prefix(), * respectively. * * \note Note that H5Lmove() does not modify the value of the link; the new * link points to the same object as the original link pointed to. * Furthermore, if the object pointed to by the original link was already * open with a valid object identifier, that identifier will remain valid * after the call to H5Lmove(). * * \attention Exercise care in moving links as it is possible to render data in * a file inaccessible with H5Lmove(). If the link being moved is on * the only path leading to an HDF5 object, that object may become * permanently inaccessible in the file. * * \since 1.8.0 * *------------------------------------------------------------------------- */ H5_DLL herr_t H5Lmove(hid_t src_loc, const char *src_name, hid_t dst_loc, const char *dst_name, hid_t lcpl_id, hid_t lapl_id); /** * \ingroup H5L * * \brief Creates an identical copy of a link with the same creation time and * target. The new link can have a different name and be in a different * location than the original. * * \fgdt_loc_id{src_loc} * \param[in] src_name Name of the link to be copied * \fgdt_loc_id{dst_loc} * \param[in] dst_name Name to be assigned to the new copy * \lcpl_id * \lapl_id * \return \herr_t * * \details H5Lcopy() copies the link specified by \p src_name from the location * specified by \p src_loc_id to the location specified by * \p dst_loc_id. The new copy of the link is created with the name * \p dst_name. * * If \p dst_loc_id is a file identifier, \p dst_name will be * interpreted relative to that file’s root group. * * The new link is created with the creation and access property lists * specified by \p lcpl_id and \p lapl_id. The interpretation of * \p lcpl_id is limited in the manner described in the next paragraph. * * H5Lcopy() retains the creation time and the target of the original * link. However, since the link may be renamed, the character * encoding is that specified in \p lcpl_id rather than that of the * original link. Other link creation properties are ignored. * * If the link is a soft link, also known as a symbolic link, its * target is interpreted relative to the location of the copy. * * Several properties are available to govern the behavior of * H5Lcopy(). These properties are set in the link creation and access * property lists, \p lcpl_id and \p lapl_id, respectively. The * property controlling creation of missing intermediate groups is set * in the link creation property list with * H5Pset_create_intermediate_group(); this function ignores any * other properties in the link creation property list. Properties * controlling character encoding, link traversals, and external link * prefixes are set in the link access property list with * H5Pset_char_encoding(), H5Pset_nlinks(), and * H5Pset_elink_prefix(). * * \note H5Lcopy() does not affect the object that the link points to. * * \attention H5Lcopy() cannot copy hard links across files as a hard link is * not valid without a target object; to copy objects from one file * to another, see H5Ocopy(). * * \see H5Ocopy() * * \since 1.8.0 * */ H5_DLL herr_t H5Lcopy(hid_t src_loc, const char *src_name, hid_t dst_loc, const char *dst_name, hid_t lcpl_id, hid_t lapl_id); /** * \ingroup H5L * * \brief Creates a hard link to an object * * \fgdta_loc_id{cur_loc} * \param[in] cur_name Name of the target object, which must already exist * \fgdta_loc_id{dst_loc} * \param[in] dst_name The name of the new link * \lcpl_id * \lapl_id * * \return \herr_t * * \details H5Lcreate_hard() creates a new hard link to a pre-existing object * in an HDF5 file. * * \p cur_loc and \p cur_name specify the location * and name, respectively, of the target object, i.e., the object that * the new hard link points to. \p dst_loc and \p dst_name specify the * location and name, respectively, of the new hard link. * * \p cur_name and \p dst_name are interpreted relative to \p cur_loc * and \p dst_loc, respectively. If \p cur_loc and \p dst_loc are the * same location, the HDF5 macro #H5L_SAME_LOC can be used for either * parameter (but not both). * * \p lcpl_id and \p lapl_id are the link creation and access property * lists associated with the new link. * * \note Hard and soft links are for use only if the target object is in the * current file. If the desired target object is in a different file from * the new link, an external link may be created with * H5Lcreate_external(). * * \note The HDF5 library keeps a count of all hard links pointing to an * object; if the hard link count reaches zero (0), the object will be * deleted from the file. Creating new hard links to an object will * prevent it from being deleted if other links are removed. The * library maintains no similar count for soft links and they can dangle. * * \note The new link may be one of many that point to that object. * * \since 1.8.0 * */ H5_DLL herr_t H5Lcreate_hard(hid_t cur_loc, const char *cur_name, hid_t dst_loc, const char *dst_name, hid_t lcpl_id, hid_t lapl_id); /** * \ingroup H5L * * \brief Creates a soft link * * \param[in] link_target An HDF5 path name * \fgdta_loc_id{link_loc_id} * \param[in] link_name The name of the new link * \lcpl_id * \lapl_id * * \return \herr_t * * \details H5Lcreate_soft() creates a new soft link to an object in an HDF5 * file. * * \p link_target specifies the HDF5 path name the soft link contains. * \p link_target can be an arbitrary HDF5 path name and is * interpreted only at lookup time. This path may be absolute in the * file or relative to \p link_loc_id. * * \p link_loc_id and \p link_name specify the location and name, * respectively, of the new soft link. \p link_name is interpreted * relative to \p link_loc_id and must contain only the name of the soft * link; \p link_name may not contain any additional path elements. * * If \p link_loc_id is a group identifier, the object pointed to by * \p link_name will be accessed as a member of that group. If * \p link_loc_id is a file identifier, the object will be accessed as a * member of the file's root group. * * \p lcpl_id and \p lapl_id are the link creation and access property * lists associated with the new link. * * For instance, if target_path is \c ./foo, \p link_loc_id specifies * \c ./x/y/bar, and the name of the new link is \c new_link, then a * subsequent request for \c ./x/y/bar/new_link will return same the * object as would be found at \c ./foo. * * \note H5Lcreate_soft() is for use only if the target object is in the * current file. If the desired target object is in a different file from * the new link, use H5Lcreate_external() to create an external link. * * \note Soft links and external links are also known as symbolic links as they * use a name to point to an object; hard links employ an object’s * address in the file. * * \note Unlike hard links, a soft link in an HDF5 file is allowed to dangle, * meaning that the target object need not exist at the time that the * link is created. * * \note The HDF5 library does not keep a count of soft links as it does of * hard links. * * \note The new link may be one of many that point to that object. * * \see H5Lcreate_hard(), H5Lcreate_external() * * \since 1.8.0 * */ H5_DLL herr_t H5Lcreate_soft(const char *link_target, hid_t link_loc_id, const char *link_name, hid_t lcpl_id, hid_t lapl_id); /** * \ingroup H5L * * \brief Removes a link from a group * * \fgdta_loc_id * \param[in] name Name of the link to delete * \lapl_id * * \return \herr_t * * \details H5Ldelete() removes the link specified by \p name from the location * \p loc_id. * * If the link being removed is a hard link, H5Ldelete() also * decrements the link count for the object to which name points. * Unless there is a duplicate hard link in that group, this action * removes the object to which name points from the group that * previously contained it. * * Object headers keep track of how many hard links refer to an * object; when the hard link count, also referred to as the reference * count, reaches zero, the object can be removed from the file. The * file space associated will then be released, i.e., identified in * memory as freespace. Objects which are open are not removed until * all identifiers to the object are closed. * * \attention Exercise caution in the use of H5Ldelete(); if the link being * removed is on the only path leading to an HDF5 object, that * object may become permanently inaccessible in the file. * * \see H5Lcreate_hard(), H5Lcreate_soft(), H5Lcreate_external() * * \since 1.8.0 * */ H5_DLL herr_t H5Ldelete(hid_t loc_id, const char *name, hid_t lapl_id); /** * \ingroup H5L * * \brief Removes the \Emph{n}-th link in a group * * \fgdta_loc_id * \param[in] group_name Name of subject group * \param[in] idx_type Index or field which determines the order * \param[in] order Order within field or index * \param[in] n Link for which to retrieve information * \lapl_id * * \return \herr_t * * \details H5Ldelete_by_idx() removes the \Emph{n}-th link in a group * according to the specified order, \p order, in the specified index, * \p index. * * If \p loc_id specifies the group in which the link resides, * \p group_name can be a dot (\c .). * * \see H5Ldelete() * * \since 1.8.0 * */ H5_DLL herr_t H5Ldelete_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type, H5_iter_order_t order, hsize_t n, hid_t lapl_id); /** * \ingroup H5L * * \brief Returns the value of a link * * \fgdta_loc_id * \param[in] name Link name * \param[out] buf The buffer to hold the link value * \param[in] size Maximum number of bytes of link value to be returned * \lapl_id * * \return \herr_t * * \details H5Lget_val() returns tha value of link \p name. For smbolic links, * this is the path to which the link points, including the null * terminator. For external and user-defined links, it is the link * buffer. * * \p size is the size of \p buf and should be the size of the link * value being returned. This size value can be determined through a * call to H5Lget_info(); it is returned in the \c val_size field of * the \ref H5L_info_t \c struct. * * If \p size is smaller than the size of the returned value, then the * string stored in \p buf will be truncated to \p size bytes. For * soft links, this means that the value will not be null terminated. * * In the case of external links, the target file and object names are * extracted from \p buf by calling H5Lunpack_elink_val(). * * The link class of link \p name can be determined with a call to * H5Lget_info(). * * \p lapl_id specifies the link access property list associated with * the link \p name. In the general case, when default link access * properties are acceptable, this can be passed in as #H5P_DEFAULT. An * example of a situation that requires a non-default link access * property list is when the link is an external link; an external * link may require that a link prefix be set in a link access * property list (see H5Pset_elink_prefix()). * * This function should be used only after H5Lget_info() has been * called to verify that \p name is a symbolic link. This can be * deteremined from the \c link_type field of the \ref H5L_info_t * \c struct. * * \note This function will fail if called on a hard link. * * \see H5Lget_val_by_idx() * * \since 1.8.0 * */ H5_DLL herr_t H5Lget_val(hid_t loc_id, const char *name, void *buf /*out*/, size_t size, hid_t lapl_id); /** * \ingroup H5L * * \brief Retrieves value of the \Emph{n}-th link in a group, according to the order within an index * * \fgdta_loc_id * \param[in] group_name Group name * \param[in] idx_type Type of index * \param[in] order Order within field or index * \param[in] n Link position for which to retrieve information * \param[out] buf The buffer to hold the link value * \param[in] size Maximum number of bytes of link value to be returned * \lapl_id * * \return \herr_t * * \details H5Lget_val_by_idx() retrieves the value of the \Emph{n}-th link in * a group, according to the specified order, \p order, within an * index, \p index. * * For soft links, the value is an HDF5 path name. * * For external links, this is a compound value containing file and * path name information; to use this external link information, it * must first be decoded with H5Lunpack_elink_val() * * For user-defined links, this value will be described in the * definition of the user-defined link type. * * \p loc_id specifies the location identifier of the group specified * by \p group_name. * * \p group_name specifies the group in which the link exists. If * \p loc_id already specifies the group in which the link exists, * \p group_name must be a dot (\c .). * * The size in bytes of link_val is specified in \p size. The size * value can be determined through a call to H5Lget_info_by_idx(); it * is returned in the \c val_size field of the \ref H5L_info_t * \c struct. If * size is smaller than the size of the returned value, then the * string stored in link_val will be truncated to size bytes. For soft * links, this means that the value will not be null terminated. * * If the type of the link is unknown or uncertain, H5Lget_val_by_idx() * should be called only after the type has been determined via a call * to H5Lget_info_by_idx(). * * \note This function will fail if called on a hard link. * * \see H5Lget_val() * * \since 1.8.0 * */ H5_DLL herr_t H5Lget_val_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type, H5_iter_order_t order, hsize_t n, void *buf /*out*/, size_t size, hid_t lapl_id); /** * \ingroup H5L * * \brief Determines whether a link with the specified name exists in a group * * \fgdta_loc_id * \param[in] name Link name * \lapl_id * * \return \herr_t * * \details H5Lexists() allows an application to determine whether the link \p * name exists in the location specified by \p loc_id. The link may be * of any type; only the presence of a link with that name is checked. * * Note that H5Lexists() verifies only that the target link exists. If * name includes either a relative path or an absolute path to the * target link, intermediate steps along the path must be verified * before the existence of the target link can be safely checked. If * the path is not verified and an intermediate element of the path * does not exist, H5Lexists() will fail. The example in the next * paragraph illustrates one step-by-step method for verifying the * existence of a link with a relative or absolute path. * * \Bold{Example:} Use the following steps to verify the existence of * the link \c datasetD in the \c group group1/group2/softlink_to_group3/, * where \c group1 is a member of the group specified by \c loc_id: * * 1. First use H5Lexists() to verify that \c group1 exists. * 2. If \c group1 exists, use H5Lexists() again, this time with name * set to \c group1/group2, to verify that \c group2 exists. * 3. If \c group2 exists, use H5Lexists() with name set to * \c group1/group2/softlink_to_group3 to verify that * \c softlink_to_group3 exists. * 4. If \c softlink_to_group3 exists, you can now safely use * H5Lexists() with \c name set to * \c group1/group2/softlink_to_group3/datasetD to verify that the * target link, \c datasetD, exists. * * If the link to be verified is specified with an absolute path, the * same approach should be used, but starting with the first link in * the file’s root group. For instance, if \c datasetD were in * \c /group1/group2/softlink_to_group3, the first call to H5Lexists() * would have name set to \c /group1. * * Note that this is an outline and does not include all necessary * details. Depending on circumstances, for example, you may need to * verify that an intermediate link points to a group and that a soft * link points to an existing target. * * \note The behavior of H5Lexists() was changed in the 1.10 release in the * case where the root group, \c "/", is the name of the link. This * change is described below: *
    *
  1. Let \c file denote a valid HDF5 file identifier, and let \c lapl * denote a valid link access property list identifier. A call to * H5Lexists() with arguments \c file, \c "/", and \c lapl * returns a positive value; in other words, * \Code{H5Lexists(file, "/", lapl)} returns a positive value. * In HDF5 version 1.8.16, this function returns 0.
    2. *
  2. Let \c root denote a valid HDF5 group identifier that refers to the * root group of an HDF5 file, and let \c lapl denote a valid link * access property list identifier. A call to H5Lexists() with * arguments c root, \c "/", and \c lapl returns a positive value; * in other words, \Code{H5Lexists(root, "/", lapl)} returns a postive * value. In HDF5 version 1.8.16, this function returns 0.
    3. *
* Note that the function accepts link names and path names. This is * potentially misleading to callers, and we plan to separate the * functionality for link names and path names in a future release. * * \attention H5Lexists() checks the existence of only the final element in a * relative or absolute path; it does not check any other path * elements. The function will therefore fail when both of the * following conditions exist: * - \c name is not local to the group specified by \c loc_id or, * if \c loc_id is something other than a group identifier, \c name * is not local to the root group. * - Any element of the relative path or absolute path in name, * except the target link, does not exist. * * \version 1.10.0 Function behavior changed in this release. (See the note.) * \since 1.8.0 * */ H5_DLL htri_t H5Lexists(hid_t loc_id, const char *name, hid_t lapl_id); /** * \ingroup H5L * * \brief Returns information about a link * * \fgdta_loc_id * \param[in] name Link name * \param[out] linfo Buffer in which link information is returned * \lapl_id * * \return \herr_t * * \details H5Lget_info() returns information about the specified link through * the \p linfo argument. * * The location identifier, \p loc_id, specifies the location of the * link. A link name, \p name, interpreted relative to \p loc_id, * specifies the link being queried. * * \p lapl_id is the link access property list associated with the * link name. In the general case, when default link access properties * are acceptable, this can be passed in as #H5P_DEFAULT. An example * of a situation that requires a non-default link access property * list is when the link is an external link; an external link may * require that a link prefix be set in a link access property list * (see H5Pset_elink_prefix()). * * H5Lget_info() returns information about name in the data structure * H5L_info_t, which is described below and defined in H5Lpublic.h. * This structure is returned in the buffer \p linfo. * \snippet this H5L_info_t_snip * In the above struct, \c type specifies the link class. Valid values * include the following: * \link_types * There will be additional valid values if user-defined links have * been registered. * * \p corder specifies the link’s creation order position while * \p corder_valid indicates whether the value in corder is valid. * * If \p corder_valid is \c TRUE, the value in \p corder is known to * be valid; if \p corder_valid is \c FALSE, the value in \p corder is * presumed to be invalid; \p corder starts at zero (0) and is * incremented by one (1) as new links are created. But * higher-numbered entries are not adjusted when a lower-numbered link * is deleted; the deleted link's creation order position is simply * left vacant. In such situations, the value of \p corder for the * last link created will be larger than the number of links remaining * in the group. * * \p cset specifies the character set in which the link name is * encoded. Valid values include the following: * \csets * This value is set with H5Pset_char_encoding(). * * \c address and \c val_size are returned for hard and symbolic * links, respectively. Symbolic links include soft and external links * and some user-defined links. * * If the link is a hard link, \c address specifies the file address * that the link points to. * * If the link is a symbolic link, \c val_size will be the length of * the link value, e.g., the length of the HDF5 path name with a null * terminator. * * \version 1.8.2 Fortran subroutine added in this release. * \version 1.8.4 Fortran subroutine syntax changed in this release. * * \since 1.8.0 * */ H5_DLL herr_t H5Lget_info(hid_t loc_id, const char *name, H5L_info_t *linfo, hid_t lapl_id); /** * \ingroup H5L * * \brief Retrieves metadata for a link in a group, according to the order * within a field or index * * \loc_id * \param[in] group_name Group name * \idx_type * \order * \param[in] n Link position for which to retrieve information * \param[out] linfo Buffer in which link information is returned * \lapl_id * * \return \herr_t * * \details H5get_info_by_idx() returns the metadata for a link in a group * according to a specified field or index and a specified order. The * link for which information is to be returned is specified by \p * idx_type, \p order, and \p n as follows: * * - \p idx_type specifies the field by which the links in \p * group_name are ordered. The links may be indexed on this field, * in which case operations seeking specific links are likely to * complete more quickly. * - \p order specifies the order in which * the links are to be referenced for the purposes of this function. * - \p n specifies the position of the subject link. Note that this * count is zero-based; 0 (zero) indicates that the function will * return the value of the first link; if \p n is 5, the function * will return the value of the sixth link; etc. * * For example, assume that \p idx_type, \p order, and \p n are * #H5_INDEX_NAME, #H5_ITER_DEC, and 5, respectively. #H5_INDEX_NAME * indicates that the links are accessed in lexicographic order by * their names. #H5_ITER_DEC specifies that the list be traversed in * reverse order, or in decremented order. And 5 specifies that this * call to the function will return the metadata for the 6th link * (\c n + 1) from the end. * * See H5Literate() for a list of valid values and further discussion * regarding \p idx_type and \p order. * * If \p loc_id specifies the group in which the link resides, * \p group_name can be a dot (\c .). * * \version 1.8.4 Fortran subroutine syntax changed in this release. * \version 1.8.2 Fortran subroutine added in this release. * * \since 1.8.0 * */ H5_DLL herr_t H5Lget_info_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type, H5_iter_order_t order, hsize_t n, H5L_info_t *linfo, hid_t lapl_id); /** * \ingroup H5L * * \brief Retrieves name of the \Emph{n}-th link in a group, according to the * order within a specified field or index * * \loc_id * \param[in] group_name Group name * \idx_type * \order * \param[in] n Link position for which to retrieve information * \param[out] name Buffer in which link name is returned * \param[in] size Size in bytes of \p name * \lapl_id * * \return Returns the size of the link name if successful; otherwise returns a * negative value. * * \details H5get_name_by_idx() retrieves the name of the \Emph{n}-th link in a * group, according to the specified order, \p order, within a specified * field or index, \p idx_type. * * \p idx_type specifies the index that is used. Valid values include * the following: * \indexes * * \p order specifies the order in which objects are inspected along * the index specified in \p idx_type. Valid values include the * following: * \orders * * If \p loc_id specifies the group in which the link resides, * \p group_name can be a dot (\c .). * * The size in bytes of name is specified in \p size. If \p size is * unknown, it can be determined via an initial H5Lget_name_by_idx() * call with name set to NULL; the function's return value will be the * size of the name. * * \note Please note that in order for the specified index to correspond to the * creation order index, \p order must be set to #H5_ITER_INC or * #H5_ITER_DEC when calling H5Lget_name_by_idx(). \note The index \p n * passed to H5Lget_name_by_idx() is the index of the link within the * link table, sorted according to \p order and \p idx_type. If order is * #H5_ITER_NATIVE, then the link table is not sorted, and it does not * matter what \p idx_type is. Specifying #H5_ITER_NATIVE does not * guarantee any particular order, only that it remains consistent. * * \since 1.8.0 * */ H5_DLL ssize_t H5Lget_name_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type, H5_iter_order_t order, hsize_t n, char *name /*out*/, size_t size, hid_t lapl_id); /** * \ingroup TRAV * * \brief Iterates over links in a group, with user callback routine, * according to the order within an index. * * \group_id{grp_id} * \idx_type * \order * \param[in,out] idx Pointer to an iteration index to allow * continuing a previous iteration * \op * \op_data * \return \success{The return value of the first operator that returns * non-zero, or zero if all members were processed with no * operator returning non-zero.} * \return \failure{Negative if an error occurs in the library, or the negative * value returned by one of the operators.} * * \details H5Literate() iterates through the links in a file or * group, \p group_id, in the order of the specified * index, \p idx_type, using a user-defined callback routine * \p op. H5Literate() does not recursively follow links into * subgroups of the specified group. * * Three parameters are used to manage progress of the iteration: * \p idx_type, \p order, and \p idx_p. * * \p idx_type specifies the index to be used. If the links have * not been indexed by the index type, they will first be sorted by * that index then the iteration will begin; if the links have been * so indexed, the sorting step will be unnecessary, so the iteration * may begin more quickly. * * \p order specifies the order in which objects are to be inspected * along the index \p idx_type. * * \p idx_p tracks the iteration and allows an iteration to be * resumed if it was stopped before all members were processed. It is * passed in by the application with a starting point and returned by * the library with the point at which the iteration stopped. * * \p op_data is a user-defined pointer to the data required to * process links in the course of the iteration. This pointer is * passed back to each step of the iteration in the \p op callback * function's \p op_data parameter. \p op is invoked for each link * encounter. * * \p op_data is passed to and from each iteration and can be used to * supply or aggregate information across iterations. * * \remark Same pattern of behavior as H5Giterate(). * * \note This function is also available through the H5Literate() macro. * * \warning The behavior of H5Literate() is undefined if the link * membership of \p group_id changes during the iteration. * This does not limit the ability to change link destinations * while iterating, but caution is advised. * * * \since 1.8.0 * * \see H5Literate_by_name(), H5Lvisit(), H5Lvisit_by_name() * */ H5_DLL herr_t H5Literate(hid_t grp_id, H5_index_t idx_type, H5_iter_order_t order, hsize_t *idx, H5L_iterate_t op, void *op_data); /** * \ingroup TRAV * * \brief Iterates through links in a group * * \loc_id * \param[in] group_name Group name * \idx_type * \order * \param[in,out] idx iteration position at which to start (\Emph{IN}) or * position at which an interrupted iteration may be restarted * (\Emph{OUT}) * \op * \op_data * \lapl_id * \return \success{The return value of the first operator that returns * non-zero, or zero if all members were processed with no * operator returning non-zero.} * \return \failure{Negative if an error occurs in the library, or the negative * value returned by one of the operators.} * * \details H5Literate_by_name() iterates through the links in a group * specified by \p loc_id and \p group_name, in the order of the * specified index, \p idx_type, using a user-defined callback routine * \p op. H5Literate_by_name() does not recursively follow links into * subgroups of the specified group. * * \p idx_type specifies the index to be used. If the links have not * been indexed by the index type, they will first be sorted by that * index then the iteration will begin; if the links have been so * indexed, the sorting step will be unnecessary, so the iteration may * begin more quickly. Valid values include the following: * \indexes * * \p order specifies the order in which objects are to be inspected * along the index specified in \p idx_type. Valid values include the * following: * \orders * * \p idx allows an interrupted iteration to be resumed; it is * passed in by the application with a starting point and returned by * the library with the point at which the iteration stopped. * * \note H5Literate_by_name() is not recursive. In particular, if a member of * \p group_name is found to be a group, call it \c subgroup_a, * H5Literate_by_name() does not examine the members of \c subgroup_a. * When recursive iteration is required, the application must handle the * recursion, explicitly calling H5Literate_by_name1() on discovered * subgroups. * * \note H5Literate_by_name() assumes that the membership of the group being * iterated over remains unchanged through the iteration; if any of the * links in the group change during the iteration, the function’s * behavior is undefined. Note, however, that objects pointed to by the * links can be modified. * * \note H5Literate_by_name() is the same as H5Giterate(), except that * H5Giterate() always proceeds in lexicographic order. * * \version 1.8.8 Fortran subroutine added. * * \since 1.8.0 * */ H5_DLL herr_t H5Literate_by_name(hid_t loc_id, const char *group_name, H5_index_t idx_type, H5_iter_order_t order, hsize_t *idx, H5L_iterate_t op, void *op_data, hid_t lapl_id); /** * \ingroup TRAV * * \brief Recursively visits all links starting from a specified group * * \group_id{grp_id} * \idx_type * \order * \op * \op_data * \return \success{The return value of the first operator that returns * non-zero, or zero if all members were processed with no * operator returning non-zero.} * \return \failure{Negative if an error occurs in the library, or the negative * value returned by one of the operators.} * * \details H5Lvisit() is a recursive iteration function to visit all links in * and below a group in an HDF5 file, thus providing a mechanism for * an application to perform a common set of operations across all of * those links or a dynamically selected subset. For non-recursive * iteration across the members of a group, see H5Literate(). * * The group serving as the root of the iteration is specified by its * group or file identifier, \p group_id. * * Two parameters are used to establish the iteration: \p idx_type and * \p order. * * \p idx_type specifies the index to be used. If the links have not * been indexed by the index type, they will first be sorted by that * index then the iteration will begin; if the links have been so * indexed, the sorting step will be unnecessary, so the iteration may * begin more quickly. Valid values include the following: * \indexes * * Note that the index type passed in \p idx_type is a best effort * setting. If the application passes in a value indicating iteration * in creation order and a group is encountered that was not tracked * in creation order, that group will be iterated over in * lexicographic order by name, or name order. (Name order is the * native order used by the HDF5 library and is always available.) * * \p order specifies the order in which objects are to be inspected * along the index specified in \p idx_type. Valid values include the * following: * \orders * * \p op is a callback function of type \ref H5L_iterate_t that is invoked * for each link encountered. * \snippet this H5L_iterate_t_snip * * The \ref H5L_info_t struct is defined (in H5Lpublic.h) as follows: * \snippet this H5L_info_t_snip * * The possible return values from the callback function, and the * effect of each, are as follows: * \li Zero causes the visit iterator to continue, returning zero when * all group members have been processed. * \li A positive value causes the visit iterator to immediately * return that positive value, indicating short-circuit success. * \li A negative value causes the visit iterator to immediately * return that value, indicating failure. * * The H5Lvisit() \p op_data parameter is a user-defined pointer to * the data required to process links in the course of the iteration. * This pointer is passed back to each step of the iteration in the * \p op callback function's \p op_data parameter. * * H5Lvisit() and H5Ovisit() are companion functions: one for * examining and operating on links; the other for examining and * operating on the objects that those links point to. Both functions * ensure that by the time the function completes successfully, every * link or object below the specified point in the file has been * presented to the application for whatever processing the * application requires. * * \since 1.8.0 * * \see H5Literate() * */ H5_DLL herr_t H5Lvisit(hid_t grp_id, H5_index_t idx_type, H5_iter_order_t order, H5L_iterate_t op, void *op_data); /** * \ingroup TRAV * * \brief Recursively visits all links starting from a specified group * * \loc_id * \param[in] group_name Group name * \idx_type * \order * \op * \op_data * \lapl_id * * \return \herr_t * * \details H5Lvisit_by_name() is a recursive iteration function to visit all * links in and below a group in an HDF5 file, thus providing a * mechanism for an application to perform a common set of operations * across all of those links or a dynamically selected subset. For * non-recursive iteration across the members of a group, see * H5Literate(). * * The group serving as the root of the iteration is specified by the * \p loc_id / \p group_name parameter pair. \p loc_id specifies a * file or group; group_name specifies either a group in the file * (with an absolute name based in the file’s root group) or a group * relative to \p loc_id. If \p loc_id fully specifies the group that * is to serve as the root of the iteration, group_name should be '.' * (a dot). (Note that when \p loc_id fully specifies the the group * that is to serve as the root of the iteration, the user may wish to * consider using H5Lvisit() instead of H5Lvisit_by_name().) * * Two parameters are used to establish the iteration: \p idx_type and * \p order. * * \p idx_type specifies the index to be used. If the links have not * been indexed by the index type, they will first be sorted by that * index then the iteration will begin; if the links have been so * indexed, the sorting step will be unnecesary, so the iteration may * begin more quickly. Valid values include the following: * \indexes * * Note that the index type passed in \p idx_type is a best effort * setting. If the application passes in a value indicating iteration * in creation order and a group is encountered that was not tracked * in creation order, that group will be iterated over in * lexicographic order by name, or name order. (Name order is the * native order used by the HDF5 library and is always available.) * * \p order specifies the order in which objects are to be inspected * along the index specified in \p idx_type. Valid values include the * following: * \orders * * The \p op callback function, the related \ref H5L_info_t * \c struct, and the effect that the callback function's return value * has on the application are described in H5Lvisit(). * * The H5Lvisit_by_name() \p op_data parameter is a user-defined * pointer to the data required to process links in the course of the * iteration. This pointer is passed back to each step of the * iteration in the callback function's \p op_data parameter. * * \p lapl_id is a link access property list. In the general case, * when default link access properties are acceptable, this can be * passed in as #H5P_DEFAULT. An example of a situation that requires * a non-default link access property list is when the link is an * external link; an external link may require that a link prefix be * set in a link access property list (see H5Pset_elink_prefix()). * * H5Lvisit_by_name() and H5Ovisit_by_name() are companion * functions: one for examining and operating on links; the other for * examining and operating on the objects that those links point to. * Both functions ensure that by the time the function completes * successfully, every link or object below the specified point in the * file has been presented to the application for whatever processing * the application requires. * * \since 1.8.0 * */ H5_DLL herr_t H5Lvisit_by_name(hid_t loc_id, const char *group_name, H5_index_t idx_type, H5_iter_order_t order, H5L_iterate_t op, void *op_data, hid_t lapl_id); /* UD link functions */ /** * \ingroup H5L * * \brief Creates a link of a user-defined type * * \loc_id{link_loc_id} * \param[in] link_name Link name * \param[in] link_type User-defined link class * \param[in] udata User-supplied link information * \param[in] udata_size Size of udata buffer * \lcpl_id * \lapl_id * * \return \herr_t * * \details H5Lcreate_ud() creates a link of user-defined type \p link_type * named \p link_name at the location specified in \p link_loc_id with * user-specified data \p udata. * * \p link_name is interpreted relative to \p link_loc_id. * * Valid values for the link class of the new link, \p link_type, * include #H5L_TYPE_EXTERNAL and any user-defined link classes that * have been registered with the library. See H5Lregister() for * further information. * * The format of the information pointed to by \p udata is defined by * the user. \p udata_size specifies the size of the \p udata buffer. * \p udata may be NULL if \p udata_size is zero (0). * * The property lists specified by \p lcpl_id and \p lapl_id specify * properties used to create and access the link. * * \note The external link type, #H5L_TYPE_EXTERNAL, included in the HDF5 * library distribution, is implemented as a user-defined link type. This * was done, in part, to provide a model for the implementation of other * user-defined links. * * \since 1.8.0 * */ H5_DLL herr_t H5Lcreate_ud(hid_t link_loc_id, const char *link_name, H5L_type_t link_type, const void *udata, size_t udata_size, hid_t lcpl_id, hid_t lapl_id); /** * \ingroup H5LA * * \brief Registers a user-defined link class or changes behavior of an * existing class * * \param[in] cls Pointer to a buffer containing the struct describing the * user-defined link class * * \return \herr_t * * \details H5Lregister() registers a class of user-defined links, or changes * the behavior of an existing class. * * \p cls is a pointer to a buffer containing a copy of the * H5L_class_t struct. This struct is defined in H5Lpublic.h as * follows: * \snippet this H5L_class_t_snip * * The class definition passed with \p cls must include at least the * following: * \li An H5L_class_t version (which should be #H5L_LINK_CLASS_T_VERS) * \li A link class identifier, \c class_id * \li A traversal function, \c trav_func * * Remaining \c struct members are optional and may be passed as NULL. * * The link class passed in \c class_id must be in the user-definable * range between #H5L_TYPE_UD_MIN and #H5L_TYPE_UD_MAX * (see the table below) and will override * any existing link class with that identifier. * * As distributed, valid values of \c class_id used in HDF5 include * the following (defined in H5Lpublic.h): * \link_types * * The hard and soft link class identifiers cannot be modified or * reassigned, but the external link class is implemented as an * example in the user-definable link class identifier range. * H5Lregister() is used to register additional link classes. It could * also be used to modify the behavior of the external link class, * though that is not recommended. * * The following table summarizes existing link types and values and * the reserved and user-definable link class identifier value ranges. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Link class identifier or Value rangeDescriptionLink class or label
0 to 63Reserved range
64 to 255User-definable range
64Minimum user-defined value#H5L_TYPE_UD_MIN
64External link#H5L_TYPE_EXTERNAL
255Maximum user-defined value#H5L_TYPE_UD_MAX
255Maximum value#H5L_TYPE_MAX
-1Error#H5L_TYPE_ERROR
* * Note that HDF5 internally registers user-defined link classes only * by the numeric value of the link class identifier. An application, * on the other hand, will generally use a name for a user-defined * class, if for no other purpose than as a variable name. Assume, * for example, that a complex link type is registered with the link * class identifier 73 and that the code includes the following * assignment: * \code * H5L_TYPE_COMPLEX_A = 73 * \endcode * The application can refer to the link class with a term, * \c H5L_TYPE_COMPLEX_A, that conveys meaning to a human reviewing * the code, while HDF5 recognizes it by the more cryptic numeric * identifier, 73. * * \attention Important details and considerations include the following: * \li If you plan to distribute files or software with a * user-defined link class, please contact the Help Desk at * The HDF Group to help prevent collisions between \c class_id * values. See below. * \li As distributed with HDF5, the external link class is * implemented as an example of a user-defined link class with * #H5L_TYPE_EXTERNAL equal to #H5L_TYPE_UD_MIN. \c class_id in * the H5L_class_t \c struct must not equal #H5L_TYPE_UD_MIN * unless you intend to overwrite or modify the behavior of * external links. * \li H5Lregister() can be used only with link class identifiers * in the user-definable range (see table above). * \li The hard and soft links defined by the HDF5 library, * #H5L_TYPE_HARD and #H5L_TYPE_SOFT, reside in the reserved * range below #H5L_TYPE_UD_MIN and cannot be redefined or * modified. * \li H5Lis_registered() can be used to determine whether a desired * link class identifier is available. \Emph{Note that this * function will tell you only whether the link class identifier * has been registered with the installed copy of HDF5; it * cannot tell you whether the link class has been registered * with The HDF Group.} * \li #H5L_TYPE_MAX is the maximum allowed value for a link type * identifier. * \li #H5L_TYPE_UD_MIN equals #H5L_TYPE_EXTERNAL. * \li #H5L_TYPE_UD_MAX equals #H5L_TYPE_MAX. * \li #H5L_TYPE_ERROR indicates that an error has occurred. * * \note \Bold{Registration with The HDF Group:}\n * There are sometimes reasons to take a broader approach to registering * a user-defined link class than just invoking H5Lregister(). For * example: * \li A user-defined link class is intended for use across an * organization, among collaborators, or across a community of users. * \li An application or library overlying HDF5 invokes a user-defined * link class that must be shipped with the software. * \li Files are distributed that make use of a user-defined link class. * \li Or simply, a specific user-defined link class is thought to be * widely useful. * * In such cases, you are encouraged to register that link class with * The HDF Group's Helpdesk. The HDF Group maintains a registry of known * user-defined link classes and tracks the selected link class * identifiers. This registry is intended to reduce the risk of * collisions between \c class_id values and to help coordinate the use * of specialized link classes. * * \since 1.8.0 * */ H5_DLL herr_t H5Lregister(const H5L_class_t *cls); /** * \ingroup H5LA * * \brief Unregisters a class of user-defined links * * \param[in] id User-defined link class identifier * * \return \herr_t * * \details H5Lunregister() unregisters a class of user-defined links, * preventing them from being traversed, queried, moved, etc. * * \note A link class can be re-registered using H5Lregister(). * * \since 1.8.0 * */ H5_DLL herr_t H5Lunregister(H5L_type_t id); /** * \ingroup H5LA * * \brief Determines whether a class of user-defined links is registered * * \param[in] id User-defined link class identifier * * \return \htri_t * * \details H5Lis_registered() tests whether a user-defined link class is * currently registered, either by the HDF5 library or by the user * through the use of H5Lregister(). * * \note A link class must be registered to create new links of that type or to * traverse existing links of that type. * * \since 1.8.0 * */ H5_DLL htri_t H5Lis_registered(H5L_type_t id); /* External link functions */ /** * \ingroup H5L * * \brief Decodes external link information * * \param[in] ext_linkval Buffer containing external link information * \param[in] link_size Size, in bytes, of the \p ext_linkval buffer * \param[out] flags External link flags, packed as a bitmap (\Emph{Reserved as * a bitmap for flags; no flags are currently defined, so the * only valid value * is 0.}) * \param[out] filename Returned filename \param[out] obj_path Returned * object path, relative to \p filename * * \return \herr_t * * \details H5Lunpack_elink_val() decodes the external link information * returned by H5Lget_val() in the \p ext_linkval buffer. * * \p ext_linkval should be the buffer set by H5Lget_val() and will * consist of two NULL-terminated strings, the filename and object * path, one after the other. * * Given this buffer, H5Lunpack_elink_val() creates pointers to the * filename and object path within the buffer and returns them in * \p filename and \p obj_path, unless they are passed in as NULL. * * H5Lunpack_elink_val() requires that \p ext_linkval contain a * concatenated pair of null-terminated strings, so use of this * function on a string that is not an external link \p udata buffer * may result in a segmentation fault. This failure can be avoided by * adhering to the following procedure: *
    *
  1. Call H5Lget_info() to get the link type and the size of the * link value.
  2. *
  3. Verify that the link is an external link, i.e., that its link * type is #H5L_TYPE_EXTERNAL.
    4. *
  4. Call H5Lget_val() to get the link value.
    5. *
  5. Call H5Lunpack_elink_val() to unpack that value.
    6. *
* * \since 1.8.0 * */ H5_DLL herr_t H5Lunpack_elink_val(const void *ext_linkval /*in*/, size_t link_size, unsigned *flags, const char **filename /*out*/, const char **obj_path /*out*/); /** * \ingroup H5L * * \brief Creates an external link, a soft link to an object in a different file. * * \param[in] file_name Name of the target file containing the target object. * \param[in] obj_name Path within the target file to the target object * \fgdt_loc_id{link_loc_id} * \param[in] link_name Name of the new link, relative to \p link_loc_id * \lcpl_id * \lapl_id * \return \herr_t * * \details H5Lcreate_external() creates a new external link. An external link * is a soft link to an object in a different HDF5 file from the * location of the link, i.e., to an external object. * * \p file_name identifies the target file containing the target * object; \p obj_name specifies the path of the target object within * that file. \p obj_name must be an absolute pathname in * \p file_name, i.e., it must start at the target file’s root group, * but it is not interpreted until an application attempts to traverse * it. * * \p link_loc_id and \p link_name specify the location and name, * respectively, of the new link. \p link_name is interpreted relative * to \p link_loc_id. * * \p lcpl_id is the link creation property list used in creating the * new link. * * \p lapl_id is the link access property list used in traversing the * new link. Note that an external file opened by the traversal of an * external link is always opened with the weak file close degree * property setting, #H5F_CLOSE_WEAK (see H5Pset_fclose_degree()); * any file close degree property setting in \p lapl_id is ignored. * * An external link behaves similarly to a soft link, and like a soft * link in an HDF5 file, it may dangle: the target file and object * need not exist at the time that the external link is created. * * When the external link \p link_name is accessed, the library will * search for the target file \p file_name as described below: * * - If \p file_name is a relative pathname, the following steps are * performed: * - The library will get the prefix(es) set in the environment * variable \c HDF5_EXT_PREFIX and will try to prepend each prefix * to \p file_name to form a new \p file_name. * - If the new \p file_name does not exist or if \c HDF5_EXT_PREFIX * is not set, the library will get the prefix set via * H5Pset_elink_prefix() and prepend it to \p file_name to form a * new \p file_name. * - If the new \p file_name does not exist or no prefix is being * set by H5Pset_elink_prefix(), then the path of the file * associated with \p link_loc_id is obtained. This path can be * the absolute path or the current working directory plus the * relative path of that file when it is created/opened. The * library will prepend this path to \p file_name to form a new * \p file_name. * - If the new \p file_name does not exist, then the library will * look for \p file_name and will return failure/success * accordingly. * - If \p file_name is an absolute pathname, the library will first * try to find \p file_name. If \p file_name does not exist, * \p file_name is stripped of directory paths to form a new * \p file_name. The search for the new \p file_name then follows * the same steps as described above for a relative pathname. See * examples below illustrating how target_file_name is stripped to * form a new \p file_name. * * Note that \p file_name is considered to be an absolute pathname * when the following condition is true: * * - For Unix, the first character of \p file_name is a slash (\c /). * For example, consider a \p file_name of \c /tmp/A.h5. * If that target file does not exist, the new \p file_name after * stripping will be \c A.h5. * - For Windows, there are 6 cases: * -# \p file_name is an absolute drive with absolute pathname. * For example, consider a \p file_name of \c /tmp/A.h5. If that * target file does not exist, the new \p file_name after * stripping will be \c A.h5. * -# \p file_name is an absolute pathname without specifying drive * name. For example, consider a \p file_name of \c /tmp/A.h5. * If that target file does not exist, the new \p file_name after * stripping will be \c A.h5. * -# \p file_name is an absolute drive with relative pathname. * For example, consider a \p file_name of \c /tmp/A.h5. If that * target file does not exist, the new \p file_name after * stripping will be \c tmp\A.h5. * -# \p file_name is in UNC (Uniform Naming Convention) format with * server name, share name, and pathname. For example, consider * a \p file_name of \c /tmp/A.h5. If that target file does not * exist, the new \p file_name after stripping will be \c A.h5. * -# \p file_name is in Long UNC (Uniform Naming Convention) format * with server name, share name, and pathname. For example, * consider a \p file_name of \c /tmp/A.h5. If that target file * does not exist, the new \p file_name after stripping will be * \c A.h5. * -# \p file_name is in Long UNC (Uniform Naming Convention) format * with an absolute drive and an absolute pathname. For example, * consider a \p file_name of \c /tmp/A.h5. If that target file * does not exist, the new \p file_name after stripping will be * \c A.h5. * * The library opens target file \p file_name with the file access * property list that is set via H5Pset_elink_fapl() when the external * link link_name is accessed. If no such property list is set, the * library uses the file access property list associated with the file * of \p link_loc_id to open the target file. * * If an application requires additional control over file access * flags or the file access property list, see H5Pset_elink_cb(); this * function enables the use of an external link callback function as * described in H5L_elink_traverse_t(). * * \attention A file close degree property setting (H5Pset_fclose_degree()) in * the external link file access property list or in the external * link callback function will be ignored. A file opened by means of * traversing an external link is always opened with the weak file * close degree property setting, #H5F_CLOSE_WEAK . * * \see H5Lcreate_hard(), H5Lcreate_soft(), H5Lcreate_ud() * * \since 1.8.0 */ H5_DLL herr_t H5Lcreate_external(const char *file_name, const char *obj_name, hid_t link_loc_id, const char *link_name, hid_t lcpl_id, hid_t lapl_id); #ifdef __cplusplus } #endif #endif /* H5Lpublic_H */