Rationalization of JSON output. Pass actual URL path to URL handler.

(cherry picked from commit becce8d69a6e6cee38d4fdb78b5a4e25d570baea)

dump1090.c

@@ -681,6 +681,7 @@ static void display_stats(void) {
 void backgroundTasks(void) {
     static time_t next_stats;
     static time_t next_json;
+    time_t now = time(NULL);
 
     if (Modes.net) {
 	modesNetPeriodicWork();
@@ -697,7 +698,6 @@ void backgroundTasks(void) {
     }
 
     if (Modes.stats > 0) {
-        time_t now = time(NULL);
         if (now > next_stats) {
             if (next_stats != 0)
                 display_stats();
@@ -705,12 +705,9 @@ void backgroundTasks(void) {
         }
     }
 
-    if (Modes.json_aircraft_path) {
+    if ((Modes.json_dir || Modes.net_http_port) && now >= next_json) {
-        time_t now = time(NULL);
+        writeJsonToFile("aircraft.json", generateAircraftJson);
-        if (now >= next_json) {
+        next_json = now + Modes.json_interval;
-            writeJsonToFile(Modes.json_aircraft_path, generateAircraftJson);
-            next_json = now + Modes.json_interval;
-        }
     }
 }
 
@@ -907,14 +904,7 @@ int main(int argc, char **argv) {
             Modes.oversample = 1;
 #ifndef _WIN32
         } else if (!strcmp(argv[j], "--write-json") && more) {
-            ++j;
+            Modes.json_dir = strdup(argv[++j]);
-            Modes.json_aircraft_path = malloc(strlen(argv[j]) + 15);
-            strcpy(Modes.json_aircraft_path, argv[j]);
-            strcat(Modes.json_aircraft_path, "/aircraft.json");
-
-            Modes.json_metadata_path = malloc(strlen(argv[j]) + 15);
-            strcpy(Modes.json_metadata_path, argv[j]);
-            strcat(Modes.json_metadata_path, "/receiver.json");
         } else if (!strcmp(argv[j], "--write-json-every") && more) {
             Modes.json_interval = atoi(argv[++j]);
             if (Modes.json_interval < 1)
@@ -972,9 +962,7 @@ int main(int argc, char **argv) {
     }
     if (Modes.net) modesInitNet();
 
-    if (Modes.json_metadata_path) {
+    writeJsonToFile("receiver.json", generateReceiverJson); // once only on startup
-        writeJsonToFile(Modes.json_metadata_path, generateReceiverJson); // once only on startup
-    }
 
     // If the user specifies --net-only, just run in order to serve network
     // clients without reading data from the RTL device

dump1090.h

@@ -358,8 +358,7 @@ struct {                             // Internal state
     int   metric;                    // Use metric units
     int   mlat;                      // Use Beast ascii format for raw data output, i.e. @...; iso *...;
     int   interactive_rtl1090;       // flight table in interactive mode is formatted like RTL1090
-    char *json_aircraft_path;        // Path to json aircraft file to write, or NULL not to.
+    char *json_dir;                  // Path to json base directory, or NULL not to write json.
-    char *json_metadata_path;        // Path to json metadata file to write, or NULL not to.
     int   json_interval;             // Interval between rewriting the json aircraft file
     int   json_location_accuracy;    // Accuracy of location metadata: 0=none, 1=approx, 2=exact
 
@@ -485,9 +484,9 @@ void modesQueueOutput     (struct modesMessage *mm);
 void modesReadFromClient(struct client *c, char *sep, int(*handler)(struct client *, char *));
 void modesNetPeriodicWork (void);
 
-void writeJsonToFile(const char *path, char * (*generator) (int*));
+void writeJsonToFile(const char *file, char * (*generator) (const char*,int*));
-char *generateAircraftJson(int *len);
+char *generateAircraftJson(const char *url_path, int *len);
-char *generateReceiverJson(int *len);
+char *generateReceiverJson(const char *url_path, int *len);
 
 #ifdef __cplusplus
 }

net_io.c

@@ -667,13 +667,15 @@ int decodeHexMessage(struct client *c, char *hex) {
 //
 // Return a description of planes in json. No metric conversion
 //
-char *generateAircraftJson(int *len) {
+char *generateAircraftJson(const char *url_path, int *len) {
     time_t now = time(NULL);
     struct aircraft *a = Modes.aircrafts;
     int buflen = 1024; // The initial buffer is incremented as needed
     char *buf = (char *) malloc(buflen), *p = buf, *end = buf+buflen;
     int first = 1;
 
+    (void) url_path;  // unused
+
     p += snprintf(p, end-p,
                   "{ \"now\" : %d,\n"
                   "  \"messages\" : %u,\n"
@@ -732,10 +734,12 @@ char *generateAircraftJson(int *len) {
 //
 // Return a description of the receiver in json.
 //
-char *generateReceiverJson(int *len)
+char *generateReceiverJson(const char *url_path, int *len)
 {
     char *buf = (char *) malloc(1024), *p = buf;
 
+    (void)url_path;  // unused
+
     p += sprintf(p, "{ " \
                  "\"version\" : \"%s\", "
                  "\"refresh\" : %d",
@@ -762,16 +766,20 @@ char *generateReceiverJson(int *len)
 }
 
 // Write JSON to file
-void writeJsonToFile(const char *path, char * (*generator) (int*))
+void writeJsonToFile(const char *file, char * (*generator) (const char *,int*))
 {
 #ifndef _WIN32
+    char pathbuf[PATH_MAX];
     char tmppath[PATH_MAX];
     int fd;
     int len = 0;
     mode_t mask;
     char *content;
 
-    snprintf(tmppath, PATH_MAX, "%s.XXXXXX", path);
+    if (!Modes.json_dir)
+        return;
+
+    snprintf(tmppath, PATH_MAX, "%s/%s.XXXXXX", Modes.json_dir, file);
     tmppath[PATH_MAX-1] = 0;
     fd = mkstemp(tmppath);
     if (fd < 0)
@@ -781,7 +789,9 @@ void writeJsonToFile(const char *path, char * (*generator) (int*))
     umask(mask);
     fchmod(fd, 0644 & ~mask);
 
-    content = generator(&len);
+    snprintf(pathbuf, PATH_MAX, "/data/%s", file);
+    pathbuf[PATH_MAX-1] = 0;
+    content = generator(pathbuf, &len);
 
     if (write(fd, content, len) != len)
         goto error_1;
@@ -789,7 +799,9 @@ void writeJsonToFile(const char *path, char * (*generator) (int*))
     if (close(fd) < 0)
         goto error_2;
 
-    rename(tmppath, path);
+    snprintf(pathbuf, PATH_MAX, "%s/%s", Modes.json_dir, file);
+    pathbuf[PATH_MAX-1] = 0;
+    rename(tmppath, pathbuf);
     free(content);
     return;
 
@@ -814,7 +826,7 @@ void writeJsonToFile(const char *path, char * (*generator) (int*))
 
 static struct {
     char *path;
-    char * (*handler)(int*);
+    char * (*handler)(const char*,int*);
     char *content_type;
 } url_handlers[] = {
     { "/data/aircraft.json", generateAircraftJson, MODES_CONTENT_TYPE_JSON },
@@ -877,7 +889,10 @@ int handleHTTPRequest(struct client *c, char *p) {
     for (i = 0; url_handlers[i].path; ++i) {
         if (!strcmp(url, url_handlers[i].path)) {
             content_type = url_handlers[i].content_type;
-            content = url_handlers[i].handler(&clen);
+            content = url_handlers[i].handler(url, &clen);
+            if (!content)
+                continue;
+
             statuscode = 200;
             statusmsg = "OK";
             if (Modes.debug & MODES_DEBUG_NET) {