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208 lines
7.0 KiB
C
208 lines
7.0 KiB
C
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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* Copyright by The HDF Group. *
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* All rights reserved. *
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* *
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* This file is part of HDF5. The full HDF5 copyright notice, including *
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* terms governing use, modification, and redistribution, is contained in *
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* the COPYING file, which can be found at the root of the source code *
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* distribution tree, or in https://www.hdfgroup.org/licenses. *
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* If you do not have access to either file, you may request a copy from *
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* help@hdfgroup.org. *
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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/* This program demonstrates how to translate an external link created on
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* a Windows machine into a format that a *nix machine can read.
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* This is done by registering a new traversal function for external links.
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*
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* This example is designed to be run on Unix and will create an external
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* link with a Windows-style path. Using the traversal function below,
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* the example then successfully follows the external link.
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*
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* The external link will create a file called "u2w/u2w_target.h5".
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* The example will fail if the directory u2w does not exist.
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*/
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#include "hdf5.h"
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#include <stdlib.h>
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#include <string.h>
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/* "Windows to Unix" traversal function for external links
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*
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* Translates a filename stored in Unix format to Windows format by replacing
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* forward slashes with backslashes.
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* Makes no attempt to handle Windows drive names (e.g., "C:\"), spaces within
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* file names, quotes, etc. These are left as an exercise for the user. :)
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* Note that this may not be necessary on your system; many Windows systems can
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* understand Unix paths.
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*/
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static hid_t
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elink_unix2win_trav(const char *link_name, hid_t cur_group, const void *udata, size_t udata_size,
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hid_t lapl_id, hid_t dxpl_id)
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{
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hid_t fid;
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const char *file_name;
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const char *obj_name;
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char *new_fname = NULL; /* Buffer allocated to hold Unix file path */
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ssize_t prefix_len; /* External link prefix length */
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size_t fname_len;
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size_t start_pos; /* Initial position in new_fname buffer */
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size_t x; /* Counter variable */
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hid_t ret_value = -1;
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printf("Converting Unix path to Windows path.\n");
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if (H5Lunpack_elink_val(udata, udata_size, NULL, &file_name, &obj_name) < 0)
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goto error;
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fname_len = strlen(file_name);
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/* See if the external link prefix property is set */
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if ((prefix_len = H5Pget_elink_prefix(lapl_id, NULL, 0)) < 0)
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goto error;
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/* If so, prepend it to the filename. We assume that the prefix
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* is in the correct format for the current file system.
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*/
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if (prefix_len > 0) {
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/* Allocate a buffer to hold the filename plus prefix */
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new_fname = malloc(prefix_len + fname_len + 1);
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/* Copy the prefix into the buffer */
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if (H5Pget_elink_prefix(lapl_id, new_fname, (size_t)(prefix_len + 1)) < 0)
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goto error;
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start_pos = prefix_len;
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}
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else {
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/* Allocate a buffer to hold just the filename */
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new_fname = malloc(fname_len + 1);
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start_pos = 0;
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}
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/* We should now copy file_name into new_fname starting at position pos.
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* We'll convert '/' characters into '\' characters as we go.
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*/
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for (x = 0; file_name[x] != '\0'; x++) {
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if (file_name[x] == '/')
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new_fname[x + start_pos] = '\\';
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else
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new_fname[x + start_pos] = file_name[x];
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}
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new_fname[x + start_pos] = '\0';
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/* Now open the file and object within it */
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if ((fid = H5Fopen(new_fname, H5F_ACC_RDWR, H5P_DEFAULT)) < 0)
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goto error;
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ret_value = H5Oopen(fid, obj_name, lapl_id); /* If this fails, our return value will be negative. */
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if (H5Fclose(fid) < 0)
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goto error;
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/* Free file name if it's been allocated */
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if (new_fname)
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free(new_fname);
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return ret_value;
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error:
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/* Free file name if it's been allocated */
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if (new_fname)
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free(new_fname);
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return -1;
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}
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const H5L_class_t elink_unix2win_class[1] = {{
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H5L_LINK_CLASS_T_VERS, /* H5L_class_t version */
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H5L_TYPE_EXTERNAL, /* Link type id number */
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"unix2win external link", /* Link class name for debugging */
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NULL, /* Creation callback */
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NULL, /* Move callback */
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NULL, /* Copy callback */
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elink_unix2win_trav, /* The actual traversal function */
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NULL, /* Deletion callback */
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NULL /* Query callback */
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}};
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/* The example function.
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* Creates a file named "unix2win.h5" with an external link pointing to
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* the file "u2w/u2w_target.h5".
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*
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* Registers a new traversal function for external links and then
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* follows the external link to open the target file.
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*/
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static int
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unix2win_example(void)
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{
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hid_t fid = (-1); /* File ID */
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hid_t gid = (-1); /* Group ID */
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/* Create the target file. */
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#ifdef H5_HAVE_WIN32_API
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if ((fid = H5Fcreate("u2w\\u2w_target.h5", H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT)) < 0)
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goto error;
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#else
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if ((fid = H5Fcreate("u2w/u2w_target.h5", H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT)) < 0)
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goto error;
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#endif
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if (H5Fclose(fid) < 0)
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goto error;
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/* Create the source file with an external link in Windows format */
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if ((fid = H5Fcreate("unix2win.h5", H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT)) < 0)
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goto error;
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/* Create the external link */
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if (H5Lcreate_external("u2w/../u2w/u2w_target.h5", "/", fid, "ext_link", H5P_DEFAULT, H5P_DEFAULT) < 0)
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goto error;
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/* If we are not on Windows, assume we are on a Unix-y filesystem and
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* follow the external link normally.
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* If we are on Windows, register the unix2win traversal function so
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* that external links can be traversed.
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*/
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#ifdef H5_HAVE_WIN32_API
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/* Register the elink_unix2win class defined above to replace default
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* external links
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*/
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if (H5Lregister(elink_unix2win_class) < 0)
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goto error;
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#endif
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/* Now follow the link */
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if ((gid = H5Gopen2(fid, "ext_link", H5P_DEFAULT)) < 0)
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goto error;
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printf("Successfully followed external link.\n");
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/* Close the group and the file */
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if (H5Gclose(gid) < 0)
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goto error;
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if (H5Fclose(fid) < 0)
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goto error;
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return 0;
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error:
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printf("Error!\n");
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H5E_BEGIN_TRY
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{
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H5Gclose(gid);
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H5Fclose(fid);
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}
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H5E_END_TRY;
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return -1;
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}
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/* Main function
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*
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* Invokes the example function.
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*/
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int
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main(void)
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{
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int ret;
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printf("Testing unix2win external links.\n");
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ret = unix2win_example();
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return ret;
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}
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