Uemis downloader: handle more corner cases

After receiving another report of the Uemis downloader failing I tried to
make it more robust when unexpected things happen. The data structures
returned by the SDA are rather convoluted and not all relationships are
fully understood.

This makes sure we don't try to parse invalid dive entries, we only read
dive entries if we actually got new divelog entries, we only read dive
sites if at least one was referenced and we use a much more patient (and
hopefully, much more robust) algorithm to figure out which dive entry
corresponds to the new divelog entries.

What a pain.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

1 files changed, 54 insertions, 15 deletions

diff --git a/uemis-downloader.c b/uemis-downloader.c
index 3bb93703b..be9a3c425 100644
--- a/uemis-downloader.c
+++ b/uemis-downloader.c
@@ -49,7 +49,7 @@ static int number_of_files;
 static char *mbuf = NULL;
 static int mbuf_size = 0;
 
-static int nr_divespots = 0;
+static int nr_divespots = -1;
 
 /* helper function to parse the Uemis data structures */
 static void uemis_ts(char *buffer, void *_when)
@@ -664,7 +664,7 @@ static void parse_tag(struct dive *dive, char *tag, char *val)
  * index into yet another data store that we read out later. In order to
  * correctly populate the location and gps data from that we need to remember
  * the adresses of those fields for every dive that references the divespot. */
-static void process_raw_buffer(uint32_t deviceid, char *inbuf, char **max_divenr, bool keep_number, int *for_dive)
+static bool process_raw_buffer(uint32_t deviceid, char *inbuf, char **max_divenr, bool keep_number, int *for_dive)
 {
 	char *buf = strdup(inbuf);
 	char *tp, *bp, *tag, *type, *val;
@@ -676,6 +676,9 @@ static void process_raw_buffer(uint32_t deviceid, char *inbuf, char **max_divenr
 	int s, nr_sections = 0;
 	struct dive *dive = NULL;
 
+#if UEMIS_DEBUG & 4
+	fprintf(debugfile, "p_r_b %s\n", inbuf);
+#endif
 	if (for_dive)
 		*for_dive = -1;
 	bp = buf + 1;
@@ -684,24 +687,36 @@ static void process_raw_buffer(uint32_t deviceid, char *inbuf, char **max_divenr
 		/* this is a divelog */
 		log = true;
 		tp = next_token(&bp);
-		if (strcmp(tp, "1.0") != 0) {
+		/* is it a valid entry or nothing ? */
+		if (strcmp(tp, "1.0") != 0 || strstr(inbuf, "divelog{1.0{{{{")) {
 			free(buf);
-			return;
+			return false;
 		}
 	} else if (strcmp(tp, "dive") == 0) {
 		/* this is dive detail */
 		tp = next_token(&bp);
 		if (strcmp(tp, "1.0") != 0) {
 			free(buf);
-			return;
+			return false;
 		}
 	} else {
 		/* don't understand the buffer */
 		free(buf);
-		return;
+		return false;
 	}
-	if (log)
+	if (log) {
 		dive = uemis_start_dive(deviceid);
+	} else {
+		/* remember, we don't know if this is the right entry,
+		 * so first test if this is even a valid entry */
+		if (strstr(inbuf, "deleted{bool{true")) {
+#if UEMIS_DEBUG & 4
+			fprintf(debugfile, "p_r_b entry deleted\n");
+#endif
+			/* oops, this one isn't valid, suggest to try the previous one */
+			return false;
+		}
+	}
 	while (!done) {
 		/* the valid buffer ends with a series of delimiters */
 		if (bp >= endptr - 2 || !strcmp(bp, "{{"))
@@ -763,10 +778,12 @@ static void process_raw_buffer(uint32_t deviceid, char *inbuf, char **max_divenr
 			mark_divelist_changed(true);
 		} else { /* partial dive */
 			free(dive);
+			free(buf);
+			return false;
 		}
 	}
 	free(buf);
-	return;
+	return true;
 }
 
 static char *uemis_get_divenr(char *deviceidstr)
@@ -793,7 +810,7 @@ static char *uemis_get_divenr(char *deviceidstr)
 const char *do_uemis_import(const char *mountpath, short force_download)
 {
 	char *newmax = NULL;
-	int start, end, i, offset;
+	int start, end = -2, i, offset;
 	uint32_t deviceidnr;
 	char objectid[10];
 	char *deviceid = NULL;
@@ -831,12 +848,20 @@ const char *do_uemis_import(const char *mountpath, short force_download)
 		newmax = strdup("0");
 	start = atoi(newmax);
 	for (;;) {
+#if UEMIS_DEBUG & 4
+		fprintf(debugfile, "d_u_i inner loop start %d end %d newmax %s\n", start, end, newmax);
+#endif
 		param_buff[2] = newmax;
 		param_buff[3] = 0;
 		success = uemis_get_answer(mountpath, "getDivelogs", 3, 0, &result);
 		/* process the buffer we have assembled */
 		if (mbuf)
-			process_raw_buffer(deviceidnr, mbuf, &newmax, keep_number, NULL);
+			if (!process_raw_buffer(deviceidnr, mbuf, &newmax, keep_number, NULL)) {
+				/* if no dives were downloaded, mark end appropriately */
+				if (end == -2)
+					end = start - 1;
+				success = false;
+			}
 		if (once) {
 			char *t = first_object_id_val(mbuf);
 			if (t && atoi(t) > start)
@@ -844,6 +869,9 @@ const char *do_uemis_import(const char *mountpath, short force_download)
 			free(t);
 			once = false;
 		}
+#if UEMIS_DEBUG & 4
+		fprintf(debugfile, "d_u_i after download and parse start %d end %d newmax %s\n", start, end, newmax);
+#endif
 		/* if the user clicked cancel, exit gracefully */
 		if (import_thread_cancelled)
 			goto bail;
@@ -859,8 +887,10 @@ const char *do_uemis_import(const char *mountpath, short force_download)
 		endptr = strstr(mbuf, "{{{");
 		if (endptr)
 			*(endptr + 2) = '\0';
+		/* last object_id we parsed */
+		sscanf(newmax, "%d", &end);
 	}
-	if (sscanf(newmax, "%d", &end) != 1)
+	if (end == -2 && sscanf(newmax, "%d", &end) != 1)
 		end = start;
 #if UEMIS_DEBUG & 2
 	fprintf(debugfile, "done: read from object_id %d to %d\n", start, end);
@@ -881,13 +911,22 @@ const char *do_uemis_import(const char *mountpath, short force_download)
 		success = uemis_get_answer(mountpath, "getDive", 3, 0, &result);
 		if (mbuf) {
 			int divenr;
-			process_raw_buffer(deviceidnr, mbuf, &newmax, false, &divenr);
-			if (divenr > -1 && divenr != i) {
-				offset = i - divenr;
+			(void)process_raw_buffer(deviceidnr, mbuf, &newmax, false, &divenr);
+#if UEMIS_DEBUG & 2
+			fprintf(debugfile, "got dive %d, looking for dive %d\n", divenr, i);
+#endif
+			if (divenr != i) {
+				if (divenr == -1) {
+					offset--;
+				} else {
+					offset = i - divenr;
+				}
 #if UEMIS_DEBUG & 2
-				fprintf(debugfile, "got dive %d -> trying again with offset %d\n", divenr, offset);
+				fprintf(debugfile, " -> trying again with offset %d\n", offset);
 #endif
 				i = start - 1;
+				if (i + offset < 0)
+					break;
 				continue;
 			}
 		}