refs #596 log subprocess' output as it is generated

boottools/utils.py

@@ -3,23 +3,53 @@ import subprocess
 import re
 import os
 import configparser
+import selectors
 
 logger = logging.getLogger ('boottools')
 
 def run (args):
-    cp = subprocess.run (args, text=True, capture_output=True)
-    if cp.returncode:
-        logger.error ('command "{}" failed with rc "{}"'.format (' '.join(args), cp.returncode))
+    stdout = stderr = ''
+    logger.debug ('run 10 args "{}"'.format (' '.join(args)))
+    sel = selectors.DefaultSelector()
+    p = subprocess.Popen (args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+    sel.register (p.stdout.fileno(), selectors.EVENT_READ)
+    sel.register (p.stderr.fileno(), selectors.EVENT_READ)
+    while True:
+        events = sel.select()
+        #logger.debug (f'got {len(events)} events')
+        for key, _ in events:
+            if key.fileobj == p.stdout.fileno():
+                #logger.debug (f'reading from stdout')
+                line = p.stdout.readline()
+                if not line: break
+                stdout += line
+                logger.debug (line.rstrip())
+            elif key.fileobj == p.stderr.fileno():
+                #logger.debug (f'reading from stderr')
+                line = p.stderr.readline()
+                if not line: break
+                stderr += line
+                logger.warn (line.rstrip())
+        if p.poll() != None:
+            #logger.debug ('process exited, breaking loop')
+            break
+    sel.close()
+    #p.stdout.close()
+    #p.stderr.close()
 
-        logger.error ('stdout follows:')
-        for i in cp.stdout.strip().split('\n'): logger.error ('  ' + i)
+    logger.debug (f'p.returncode {p.returncode}')
+    if p.returncode:
+        logger.error ('command "{}" failed with rc "{}"'.format (' '.join(args), p.returncode))
+
+        #logger.error ('stdout follows:')
+        #for i in cp.stdout.strip().split('\n'): logger.error ('  ' + i)
 
         logger.error ('stderr follows:')
         for i in cp.stderr.strip().split('\n'): logger.error ('  ' + i)
 
-        raise Exception ('command "{}" failed with rc "{}"'.format (' '.join(args), cp.returncode))
-    stdout = cp.stdout.strip()
-    stderr = cp.stderr.strip()
+        raise Exception ('command "{}" failed with rc "{}"'.format (' '.join(args), p.returncode))
+    stdout = stdout.strip()
+    stderr = stderr.strip()
     return stdout, stderr
 
 def grep (regex, file):