osmq

commit cef88c8da511cdb97cdd37250514bf63bdc8c942
parent a486e2eaaabcd0dfc7a41346af4be1a5522629f9
Author: Tomas Hlavaty <tom@logand.com>
Date:   Fri, 13 Sep 2019 00:50:30 +0200

introduce osmtile-download

Diffstat:
A
osmtile-download
 | 
7
+++++++
M
osmtile.c
 | 
42
++++++++++++++----------------------------

2 files changed, 21 insertions(+), 28 deletions(-)
diff --git a/osmtile-download b/osmtile-download
@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+set -euo pipefail
+zxy=$1
+dir=$2
+url=https://tile.openstreetmap.org/
+mkdir -p $dir/$(dirname $zxy)
+exec flock -n -F $dir/$zxy.png.lock curl -s -o $dir/$zxy.png $url/$zxy.png
diff --git a/osmtile.c b/osmtile.c
@@ -106,43 +106,28 @@ static int probe(char *path) {
   return 0;
 }
 
-static void run(char *args[]) {
-  int z = fork();
-  if(z < 0) fail(1, "fork failed\n");
-  if(z) { /* parent */
-    int stat;
-    wait(&stat);
-    if(stat) fail(1, "%s failed %d\n", *args, stat);
-    return;
-  }
-  /* child */
-  execvp(*args, args);
-  fail(1, "exec %s failed\n", *args);
-}
-
 static int cached_file(int z, int x, int y, char *dir, char file[4096]) {
   int max = (1 << z) - 1;
   if(x < 0) x = max;
   if(y < 0) y = max;
   if(max < x) x = 0;
   if(max < y) y = 0;
-  char d[4096];
-  int n = snprintf(d, sizeof(d), "%s/%d/%d", dir, z, x);
-  if(n < 0 || sizeof(d) < n) fail(1, "directory path error\n");
-  n = snprintf(file, 4096, "%s/%d.png", d, y);
+  char zxy[4096];
+  int n = snprintf(zxy, sizeof(zxy), "%d/%d/%d", z, x, y);
+  if(n < 0 || sizeof(zxy) < n) fail(1, "zxy error\n");
+  n = snprintf(file, 4096, "%s/%s.png", dir, zxy);
   if(n < 0 || 4096 < n) fail(1, "file path error\n");
   if(probe(file)) return 1;
-  {
-    char url[4096];
-    int n = snprintf(url, sizeof(url), "https://tile.openstreetmap.org/%d/%d/%d.png", z, x, y);
-    if(n < 0 || sizeof(url) < n) fail(1, "url error\n");
-    char *args1[] = {"mkdir", "-p", d, NULL};
-    run(args1);
-    char *args2[] = {"curl", "-s", "-o", file, url, NULL};
-    run(args2);
-    if(!probe(file)) fail(1, "cached file '%s' not found\n", file);
+  /* download tile in background */
+  int pid = fork();
+  if(pid < 0) fail(1, "fork failed\n");
+  if(pid) { /* parent */
+    return 0;
   }
-  return 1;
+  /* child */
+  char *args[] = {"osmtile-download", zxy, dir, NULL};
+  execvp(*args, args);
+  fail(1, "exec %s failed\n", *args);
 }
 
 static void screen_size(int *w, int *h) {
@@ -190,6 +175,7 @@ static int main_tty(int argc, char *argv[]) {
   double a = a0, o = o0;
   int x = long2tilex(o, z);
   int y = lat2tiley(a, z);
+  signal(SIGCHLD, SIG_IGN);
   for(;;) {
     FILE *p = popen("w3mimgdisplay", "w");
     if(!p) fail(1, "popen w3mimgdisplay failed\n");