autoupdater: add timeouts to wget calls

The -T parameter only seems to limit the maximum time between received
packets, but not the overall run time.

This adds simple timeouts to the wget calls (5 minutes for the manifest,
30 minutes for the image). The implementation is very simple, only checking
the manifest timeout each time a line was received, and the image timeout
once a second. A more elegent fix seems like overkill, as the Lua
autoupdater will be replaced with a new implementation after Gluon 2016.2
anyways.

admin/autoupdater/files/usr/lib/lua/autoupdater/util.lua

@@ -7,14 +7,29 @@ module('autoupdater.util', package.seeall)
 
 
 -- Executes a command in the background, without parsing the command through a shell (in contrast to os.execute)
-function exec(...)
+function exec(timeout, ...)
   local pid, errno, error = nixio.fork()
   if pid == 0 then
     nixio.execp(...)
     os.exit(127)
   elseif pid > 0 then
-    local wpid, status, code = nixio.waitpid(pid)
-    return wpid and status == 'exited' and code
+    if timeout then
+      local starttime = os.time()
+      while true do
+        if os.difftime(os.time(), starttime) > timeout then
+          nixio.kill(pid, nixio.const.SIGTERM)
+        end
+
+        local wpid, status, code = nixio.waitpid(pid, 'nohang')
+        if wpid then
+          return wpid and status == 'exited' and code
+        end
+        nixio.nanosleep(1)
+      end
+    else
+      local wpid, status, code = nixio.waitpid(pid)
+      return wpid and status == 'exited' and code
+    end
   else
     return pid, errno, error
   end
@@ -69,7 +84,7 @@ function run_dir(dir)
 
   for _, entry in ipairs(files) do
     if is_ok(entry) then
-      exec(dir .. '/' .. entry)
+      exec(nil, dir .. '/' .. entry)
     end
   end
 end

admin/autoupdater/files/usr/sbin/autoupdater

@@ -129,9 +129,21 @@ local function read_manifest(mirror)
   -- Remove potential trailing slash
   mirror = mirror:gsub('/$', '')
 
+
+  local starttime = os.time()
+  local manifest_loader = io.popen(string.format("exec wget -T 120 -O- '%s/%s.manifest'", mirror, branch.name), 'r')
+
   -- Read all lines from the manifest
-  -- The upper part is saves to lines, the lower part to sigs
-  for line in io.popen(string.format("exec wget -T 120 -O- '%s/%s.manifest'", mirror, branch.name), 'r'):lines() do
+  -- The upper part is saved to lines, the lower part to sigs
+  for line in manifest_loader:lines() do
+    -- If the manifest download takes more than 5 minutes, we don't really
+    -- have a chance to download a whole image
+    if os.difftime(os.time(), starttime) > 300 then
+      io.stderr:write("Timeout while reading manifest.\n")
+      manifest_loader:close()
+      return nil
+    end
+
     if not sep then
       if line == '---' then
         sep = true
@@ -194,7 +206,8 @@ end
 
 -- Downloads the firmware image from a mirror to a given output file
 local function fetch_firmware(mirror, filename, output)
-  if autoupdater_util.exec('wget', '-T', '120', '-O', output, mirror .. '/' .. filename) ~= 0 then
+  -- Let's give the image download 30 minutes, hopefully more than enough
+  if autoupdater_util.exec(1800, 'wget', '-T', '120', '-O', output, mirror .. '/' .. filename) ~= 0 then
     io.stderr:write('Error downloading the image from ' .. mirror .. '\n')
     return false
   end