Fix segmentation fault when trying to save invalid long strings

This can occur if you have something like the following:
```
record(waveform, "foo") {
  field(FTVL, "CHAR")
  field(NELM, "10")
  info(autosaveFields, "VAL VAL$")
}
```
The `VAL$` field will cause a segmentation fault when it tries to
save it to disk. The reason this seems to happen is that on one hand,
`VAL$` is regarded by autosave as a valid field (it is a field, but
with a `$` at the end). On the other hand, when connecting a monitor,
the connection fails as the `VAL` field is not of the correcct type
as defined in `dbChannelCreate` from EPICS base.

This means that autosave will try to save the date from an unconnected
array, with uninitialised pArray, causing a segmentation fault.

Author: simon-ess

asApp/src/dbrestore.c

@@ -1522,7 +1522,8 @@ void makeAutosaveFileFromDbInfo(char *fileBaseName, char *info_name)
 	const char *info_value, *pbegin, *pend;
 	char		*fname, *falloc=NULL, field[MAX_FIELD_SIZE], realfield[MAX_FIELD_SIZE];
 	FILE 		*out_fd;
-	int			searchRecord, flen;
+	int			searchRecord, flen
+	int			long_string = 0;
 
 	if (!pdbbase) {
 		errlogPrintf("autosave:makeAutosaveFileFromDbInfo: No Database Loaded\n");
@@ -1574,9 +1575,23 @@ void makeAutosaveFileFromDbInfo(char *fileBaseName, char *info_name)
 						memcpy(field, pbegin, flen);
 						field[flen]='\0';
 						strNcpy(realfield, field, MAX_FIELD_SIZE-1);
-						if (realfield[strlen(realfield)-1] == '$') realfield[strlen(realfield)-1] = '\0';
+						if (realfield[strlen(realfield)-1] == '$') {
+							realfield[strlen(realfield)-1] = '\0';
+							long_string = 1;
+						}
 
-						if (dbFindField(pdbentry, realfield) == 0) {
+						/*
+						 * To be clear: This checks that /if/ something is a long
+						 * string, then we have to match it against a valid field
+						 * type; see dbChannelCreate in dbChannel.c from EPICS
+						 * base.
+						 */
+						if ((dbFindField(pdbentry, realfield) == 0) &&
+							(!long_string ||
+								(pdbentry->pflddes->field_type == DBF_STRING ||
+								(pdbentry->pflddes->field_type >= DBF_INLINK &&
+								 pdbentry->pflddes->field_type <= DBF_FWDLINK))))
+						{
 							fprintf(out_fd, "%s.%s\n", dbGetRecordName(pdbentry), field);
 						} else {
 							printf("makeAutosaveFileFromDbInfo: %s.%s not found\n", dbGetRecordName(pdbentry), field);