WIP Let GMT detect if DCW version on server has been updated

src/gmt_dcw.c

@@ -89,6 +89,32 @@ static char *GMT_DCW_continents[GMT_DCW_N_CONTINENTS] = {"Africa", "Antarctica",
 
 /* Local functions only visible inside this file */
 
+GMT_LOCAL bool gmtdcw_need_refresh (struct GMT_CTRL *GMT, char *fpath) {
+	/* Obtains versions from both local and cloud versions and returns true if we must refresh */
+	FILE *fp = NULL;
+	char this_version[GMT_LEN16] = {""}, cloud_version[GMT_LEN16] = {""};
+	char path[PATH_MAX] = {""};
+	int tmajor, tminor, tpatch = 0, cmajor, cminor, cpatch = 0;
+	int cdfid;
+
+	if (gmt_nc_open (GMT, fpath, NC_NOWRITE, &cdfid)) return true;	/* fpath is dcw-gmt.nc so if not found we have work to do */
+	/* Get version attribute */
+	gmt_M_memset (this_version, strlen (this_version), char);
+	if (nc_get_att_text (cdfid, NC_GLOBAL, "version", this_version)) return true;	/* If we cannot read version then what file are we reading here? */
+	gmt_nc_close (GMT, cdfid);	/* Done with reading netCDF file */
+	sprintf (path, "%s/geography/dcw/VERSION", GMT->session.USERDIR);	/* Open local VERSION file which we know is fresh */
+	if ((fp = fopen (path, "r")) && fscanf (fp, "%s\n", cloud_version) < 1) return false;	/* Not good, cannot happen but also safety valve */
+	fclose (fp);	/* Done reading from VERSION */
+	gmt_strrepc (this_version,  '.', ' ');	/* Get rid of periods */
+	gmt_strrepc (cloud_version, '.', ' ');	/* Get rid of periods */
+	sscanf (this_version,  "%d %d %d", &tmajor, &tminor, &tpatch);	/* Get the version major, minor and patch numbers */
+	sscanf (cloud_version, "%d %d %d", &cmajor, &cminor, &cpatch);
+	if (cmajor > tmajor) return true;	/* Cloud major version is more recent, must refresh */
+	if (cminor > tminor) return true;	/* Cloud major equals this major, but cloud minor version is more recent so must refresh */
+	if (cpatch > tpatch) return true;	/* Cloud major and minor equals this major and minor, but cloud patch is more recent so must refresh */
+	return false;	/* No, we are up to date */
+}
+
 GMT_LOCAL bool gmtdcw_get_path (struct GMT_CTRL *GMT, char *name, char *suffix, char *path) {
 	/* This is the order of checking:
 	 * 1. Check in GMT->session.DCWDIR, if set
@@ -116,7 +142,36 @@ GMT_LOCAL bool gmtdcw_get_path (struct GMT_CTRL *GMT, char *name, char *suffix,
 		}
 	}
 	if (GMT->session.USERDIR) {	/* Check user dir via remote download */
+		int action;
 		char remote_path[PATH_MAX] = {""};
+		/* First check what the DCW version is on the server */
+		sprintf (path, "%s/geography/dcw/VERSION", GMT->session.USERDIR);
+		if ((action = gmtlib_refresh_file (GMT->parent, path)) == GMT_NOTSET) return false;
+		if (action == GMT_YES_DOWNLOAD) {	/* Update the VERSION file before checking version */
+			sprintf (path, "%s/geography/dcw", GMT->session.USERDIR);	/* Local directory destination */
+			if (access (path, R_OK) && gmt_mkdir (path)) {	/* Must first create the directory */
+				GMT_Report (GMT->parent, GMT_MSG_ERROR, "Unable to create GMT directory : %s\n", path);
+				return false;
+			}
+			sprintf (path, "%s/geography/dcw/VERSION", GMT->session.USERDIR);
+			snprintf (remote_path, PATH_MAX, "%s/geography/dcw/VERSION", gmt_dataserver_url (GMT->parent));	/* Unique remote path */
+			if (gmt_download_file (GMT, "VERSION", remote_path, path, true)) {
+				GMT_Report (GMT->parent, GMT_MSG_ERROR, "Unable to obtain remote file %s\n", remote_path);
+				return false;
+			}
+			else	/* Successfully downloaded the first time */
+				GMT_Report (GMT->parent, GMT_MSG_INFORMATION, "Refreshed DCW VERSION file %s\n", path);
+		}
+		/* First check if the netCDF file is here and if it needs refreshing */
+		sprintf (path, "%s/geography/dcw/dcw-gmt.nc", GMT->session.USERDIR);
+		if (access (path, R_OK) == 0) {	/* Previously downloaded, check if outdated */
+			if (gmtdcw_need_refresh (GMT, path)) {	/* Yep, wipe older files so new can be downloaded */
+				sprintf (path, "%s/geography/dcw", GMT->session.USERDIR);
+				if (gmt_remove_dir (GMT->parent, path, false)) {
+					GMT_Report (GMT->parent, GMT_MSG_ERROR, "Unable to remove directory %s\n", path);
+				}
+			}
+		}
 		sprintf (path, "%s/geography/dcw/%s%s", GMT->session.USERDIR, name, suffix);
 		if (access (path, R_OK) == 0) {	/* Previously downloaded */
 			GMT_Report (GMT->parent, GMT_MSG_DEBUG, "3. DCW: Read the Digital Chart of the World from %s\n", path);

src/gmt_internals.h

@@ -53,6 +53,7 @@ struct GMT_XINGS {
 EXTERN_MSC char *dlerror (void);
 #endif
 
+EXTERN_MSC int gmtlib_refresh_file (struct GMTAPI_CTRL *API, char *file);
 EXTERN_MSC void gmtlib_terminate_session ();
 EXTERN_MSC unsigned int gmtlib_pick_in_col_number (struct GMT_CTRL *GMT, unsigned int col, unsigned int *col_pos_in);
 EXTERN_MSC bool gmtlib_set_do_seconds (struct GMT_CTRL *GMT, double inc);

src/gmt_remote.c

@@ -811,6 +811,36 @@ GMT_LOCAL struct GMT_DATA_HASH *gmtremote_hash_load (struct GMT_CTRL *GMT, char
 	return (L);
 };
 
+int gmtlib_refresh_file (struct GMTAPI_CTRL *API, char *file) {
+	/* Return various codes depending on outcome:
+	 * If file does not exist, return 1 for downloading it
+	 * If file exist but unable to stat, return -1 for error
+	 * If file exist and is older than refresh_time, return 1 for re-downloading it
+	 * If file exist and is young enough, return 0 to use as is.
+	 */
+	struct stat buf;
+	time_t mod_time, right_now = time (NULL);	/* Unix time right now */
+
+	if (access (file, R_OK)) return GMT_YES_DOWNLOAD;    /* Not found locally so need to download the first time */
+
+	if (stat (file, &buf)) {	/* Should not happen, but who knows */
+		GMT_Report (API, GMT_MSG_ERROR, "Unable to get information about %s via stat - abort\n", file);
+		return GMT_NOTSET;
+	}
+
+	/*  Get the file's modification (creation) time */
+#ifdef __APPLE__
+	mod_time = buf.st_mtimespec.tv_sec;	/* Apple even has tv_nsec for nano-seconds... */
+#else
+	mod_time = buf.st_mtime;
+#endif
+
+	if ((right_now - mod_time) > (GMT_DAY2SEC_I * API->GMT->current.setting.refresh_time))
+		return GMT_YES_DOWNLOAD;	/* Older than selected number of days; Time to get a new file */
+	else
+		return GMT_NO_DOWNLOAD;	/*OK to use this file */
+}
+
 GMT_LOCAL int gmtremote_refresh (struct GMTAPI_CTRL *API, unsigned int index) {
 	/* This function is called every time we are about to access a @remotefile.
 	 * It is called twice: Once for the hash table and once for the info table.
@@ -829,8 +859,7 @@ GMT_LOCAL int gmtremote_refresh (struct GMTAPI_CTRL *API, unsigned int index) {
 	 * The result of this is that any file(s) that have changed will be removed
 	 * so that they must be downloaded again to get the new versions.
 	 */
-	struct stat buf;
-	time_t mod_time, right_now = time (NULL);	/* Unix time right now */
+	int action;
 	char indexpath[PATH_MAX] = {""}, old_indexpath[PATH_MAX] = {""}, new_indexpath[PATH_MAX] = {""}, url[PATH_MAX] = {""};
 	const char *index_file = (index == GMT_HASH_INDEX) ? GMT_HASH_SERVER_FILE : GMT_INFO_SERVER_FILE;
 	struct LOCFILE_FP *LF = NULL;
@@ -866,18 +895,9 @@ GMT_LOCAL int gmtremote_refresh (struct GMTAPI_CTRL *API, unsigned int index) {
 
 	/* Here we have the existing index file and its path is in indexpath. Check how old it is */
 
-	if (stat (indexpath, &buf)) {
-		GMT_Report (API, GMT_MSG_ERROR, "Unable to get information about %s - abort\n", indexpath);
-		return 1;
-	}
-	/*  Get its modification (creation) time */
-#ifdef __APPLE__
-	mod_time = buf.st_mtimespec.tv_sec;	/* Apple even has tv_nsec for nano-seconds... */
-#else
-	mod_time = buf.st_mtime;
-#endif
+	if ((action = gmtlib_refresh_file (API, indexpath)) == GMT_NOTSET) return 1;
 
-	if ((right_now - mod_time) > (GMT_DAY2SEC_I * GMT->current.setting.refresh_time)) {	/* Older than selected number of days; Time to get a new index file */
+	if (action == GMT_YES_DOWNLOAD) {	/* Older than selected number of days; Time to get a new index file */
 		GMT_Report (API, GMT_MSG_DEBUG, "File %s older than 24 hours, get latest from server.\n", indexpath);
 		strcpy (new_indexpath, indexpath);	/* Duplicate path name */
 		strcat (new_indexpath, ".new");		/* Append .new to the copied path */