[arch] fix -> multi-threaded download: crashing when could not retrieve download data for packages to upgrade

CHANGELOG.md

@@ -13,7 +13,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
     
 ### Fixes
 - Arch
-    - crashing when trying to upgrade AUR packages which data could not be retrieved
+    - crashing when trying to upgrade repository packages which data could not be retrieved
+    - multi-threaded download: crashing when could not retrieve download data for packages to upgrade
 
 - Installation setup
     - wrong style resources paths

bauh/gems/arch/download.py

@@ -160,6 +160,12 @@ class MultithreadedDownloadService:
         downloaded = 0
         pkgs_data = pacman.list_download_data(pkgs)
 
+        if not pkgs_data:
+            error_msg = "Could not retrieve download data of the following packages: {}".format(', '.join(pkgs))
+            watcher.print(error_msg)
+            self.logger.error(error_msg)
+            return 0
+
         for pkg in pkgs_data:
             self.logger.info('Preparing to download package: {} ({})'.format(pkg['n'], pkg['v']))
             try:

bauh/gems/arch/pacman.py

@@ -599,8 +599,8 @@ def map_provided(remote: bool = False, pkgs: Iterable[str] = None) -> Dict[str,
 def list_download_data(pkgs: Iterable[str]) -> List[Dict[str, str]]:
     _, output = system.run(['pacman', '-Si', *pkgs])
 
+    res = []
     if output:
-        res = []
         data = {'a': None, 'v': None, 'r': None, 'n': None}
 
         for l in output.split('\n'):
@@ -623,7 +623,7 @@ def list_download_data(pkgs: Iterable[str]) -> List[Dict[str, str]]:
                         res.append(data)
                         data = {'a': None, 'v': None, 'r': None, 'n': None}
 
-        return res
+    return res
 
 
 def map_updates_data(pkgs: Iterable[str], files: bool = False) -> dict: