[project @ 2005-06-21 14:17:51 by rjw]
Unique filename provider. svn path=/import/netsurf/; revision=1750
This commit is contained in:
Richard Wilson
parent
44ef42de34
commit
523eb55a24
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/*
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* This file is part of NetSurf, http://netsurf.sourceforge.net/
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* Licensed under the GNU General Public License,
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* http://www.opensource.org/licenses/gpl-license
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* Copyright 2005 Richard Wilson <info@tinct.net>
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*/
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/** \file
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* Provides a central method of obtaining unique filenames.
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*
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* A maximum of 2^24 files can be allocated at any point in time.
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*/
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#include <stdbool.h>
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "oslib/osfile.h"
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#include "netsurf/riscos/filename.h"
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#include "netsurf/utils/log.h"
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#define FULL_WORD (unsigned int)4294967295
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struct directory {
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char prefix[10]; /** directory prefix, eg '00.11.52.' */
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unsigned int low_used; /** first 32 files, 1 bit per file */
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unsigned int high_used; /** last 32 files, 1 bit per file */
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unsigned int low_persistent; /** first 32 files, 1 bit per file */
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unsigned int high_persistent; /** last 32 files, 1 bit per file */
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struct directory *next; /** next directory (sorted by prefix) */
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};
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static struct directory *root = NULL;
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static char ro_filename_buffer[12];
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static char ro_filename_directory[256];
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static struct directory *ro_filename_create_directory(const char *prefix);
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/**
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* Request a new, unique, filename.
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*
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* \param persistent keep the filename allocated across sessions
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* \return a pointer to a shared buffer containing the new filename
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*/
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char *ro_filename_request(bool persistent) {
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struct directory *dir;
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int i = -1;
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for (dir = root; dir; dir = dir->next)
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if ((dir->low_used & dir->high_used) != FULL_WORD) {
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if (dir->low_used != FULL_WORD) {
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for (i = 0; (dir->low_used & (1 << i)); i++);
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} else {
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for (i = 0; (dir->high_used & (1 << i)); i++);
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i += 32;
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}
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break;
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}
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if (i == -1) {
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/* no available slots - create a new directory */
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dir = ro_filename_create_directory(NULL);
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if (!dir) {
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LOG(("Failed to create a new directory."));
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return NULL;
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}
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i = 63;
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}
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if (i < 32) {
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dir->low_used |= (1 << i);
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if (persistent)
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dir->low_persistent |= (1 << i);
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} else {
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dir->high_used |= (1 << (i - 32));
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if (persistent)
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dir->high_persistent |= (1 << (i - 32));
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}
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sprintf(ro_filename_buffer, "%s%i", dir->prefix, i);
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return ro_filename_buffer;
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}
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/**
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* Releases a filename for future use.
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*
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* \param filename the filename to release
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*/
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void ro_filename_release(const char *filename) {
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char *last;
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char dir_prefix[16];
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int i;
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struct directory *dir;
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/* extract the prefix */
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sprintf(dir_prefix, filename);
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for (i = 0, last = dir_prefix; i < 3; i++)
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while (*last++ != '.');
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i = atoi(last);
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last[0] = '\0';
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/* modify the correct directory entry */
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for (dir = root; dir; dir = dir->next)
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if (!strcmp(dir->prefix, dir_prefix)) {
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if (i < 32) {
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dir->low_used &= ~(1 << i);
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dir->low_persistent &= ~(1 << i);
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} else {
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dir->high_used &= ~(1 << (i - 32));
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dir->high_persistent &= ~(1 << (i - 32));
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}
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return;
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}
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}
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/**
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* Initialise the filename provider and load the previous session state.
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*/
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bool ro_filename_initialise(void) {
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char s[16];
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struct directory *dir;
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FILE *fp;
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int version;
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/* create the 'CACHE_FILENAME_PREFIX' structure */
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xosfile_create_dir("<Wimp$ScrapDir>.WWW", 0);
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xosfile_create_dir("<Wimp$ScrapDir>.WWW.NetSurf", 0);
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xosfile_create_dir("<Wimp$ScrapDir>.WWW.NetSurf.Cache", 0);
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/* load the persistent file list */
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fp = fopen("Choices:WWW.NetSurf.Filename", "r");
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if (!fp) {
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LOG(("Unable to open filename record for reading."));
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return true;
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}
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if (!fgets(s, 16, fp)) {
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fclose(fp);
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return false;
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}
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version = atoi(s);
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if (version != 100) {
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LOG(("Invalid or unsupported filename record."));
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fclose(fp);
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return false;
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}
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while (fgets(s, 16, fp)) {
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if (s[strlen(s) - 1] == '\n')
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s[strlen(s) - 1] = '\0';
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dir = ro_filename_create_directory(s);
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if (!dir) {
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LOG(("Unable to load filename record for prefix '%s'.",
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s));
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fclose(fp);
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return false;
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}
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if (!fgets(s, 16, fp)) {
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fclose(fp);
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return false;
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}
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dir->low_used = dir->low_persistent = (unsigned int)
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strtoul(s, (char **)NULL, 10);
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if (!fgets(s, 16, fp)) {
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fclose(fp);
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return false;
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}
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dir->high_used = dir->high_persistent = (unsigned int)
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strtoul(s, (char **)NULL, 10);
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}
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fclose(fp);
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ro_filename_finalise();
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return true;
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}
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/**
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* Finalise the filename provider and save the previous session state.
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*/
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bool ro_filename_finalise(void) {
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struct directory *dir;
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FILE *fp;
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fp = fopen("<Choices$Write>.WWW.NetSurf.Filename", "w");
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if (!fp) {
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LOG(("Unable to open filename record for writing."));
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return false;
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}
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fprintf(fp, "100\n");
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/* dump the persistent files in the format of:
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* [prefix]\n[low used word]\n[high used word]\n */
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for (dir = root; dir; dir = dir->next)
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if ((dir->low_persistent | dir->high_persistent) != 0)
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fprintf(fp, "%s\n%u\n%u\n",
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dir->prefix,
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dir->low_persistent,
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dir->high_persistent);
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fclose(fp);
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return true;
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}
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/**
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* Deletes all files in the cache directory that are not accounted for.
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*/
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void ro_filename_flush(void) {
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// todo: delete any files that aren't known of
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// todo: delete any empty references (?)
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}
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/**
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* Creates a new directory.
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*
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* \param prefix the prefix to use, or NULL to allocate a new one
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* \return a new directory structure, or NULL on memory exhaustion
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*
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* Empty directories are never deleted, except by an explicit call to
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* ro_filename_flush().
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*/
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static struct directory *ro_filename_create_directory(const char *prefix) {
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char *last_1, *last_2;
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int result, index;
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struct directory *old_dir, *new_dir, *prev_dir = NULL;
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char dir_prefix[16];
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/* get the lowest unique prefix, or use the provided one */
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if (prefix) {
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strcpy(dir_prefix, prefix);
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} else {
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sprintf(dir_prefix, "00.00.00.");
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for (index = 1, old_dir = root; old_dir;
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index++, old_dir = old_dir->next) {
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if (strcmp(old_dir->prefix, dir_prefix))
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break;
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sprintf(dir_prefix, "%.2i.%.2i.%.2i.",
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((index >> 12) & 63),
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((index >> 6) & 63),
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((index >> 0) & 63));
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}
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}
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/* allocate a new directory */
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new_dir = (struct directory *)calloc(1,
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sizeof(struct directory));
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if (!new_dir) {
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LOG(("No memory for calloc()"));
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return NULL;
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}
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strcpy(new_dir->prefix, dir_prefix);
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/* link into the tree, sorted by prefix. */
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for (old_dir = root; old_dir; prev_dir = old_dir,
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old_dir = old_dir->next) {
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result = strcmp(old_dir->prefix, dir_prefix);
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if (result == 0) {
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free(new_dir);
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return old_dir;
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} else if (result > 0)
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break;
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}
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if (!prev_dir) {
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new_dir->next = root;
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root = new_dir;
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} else {
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new_dir->next = prev_dir->next;
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prev_dir->next = new_dir;
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}
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/* create the directory structure */
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sprintf(ro_filename_directory, "%s.", CACHE_FILENAME_PREFIX);
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last_1 = ro_filename_directory + strlen(CACHE_FILENAME_PREFIX) + 1;
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last_2 = new_dir->prefix;
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for (int i = 0; i < 3; i++) {
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*last_1++ = *last_2++;
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while (*last_2 != '.')
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*last_1++ = *last_2++;
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last_1[0] = '\0';
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xosfile_create_dir(ro_filename_directory, 0);
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}
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return new_dir;
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}
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@ -0,0 +1,22 @@
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/*
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* This file is part of NetSurf, http://netsurf.sourceforge.net/
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* Licensed under the GNU General Public License,
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* http://www.opensource.org/licenses/gpl-license
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* Copyright 2005 Richard Wilson <info@tinct.net>
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*/
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#ifndef _NETSURF_RISCOS_FILENAME_H_
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#define _NETSURF_RISCOS_FILENAME_H_
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#include <stdbool.h>
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#define CACHE_FILENAME_PREFIX "<Wimp$ScrapDir>.WWW.NetSurf.Cache"
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char *ro_filename_request(bool persistent);
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void ro_filename_release(const char *filename);
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bool ro_filename_initialise(void);
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bool ro_filename_finalise(void);
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void ro_filename_flush(void);
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#endif
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