X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/00af5ad16232b856ef1f3620a4f62f0946c681a7..da85b5f1617656e03535dc490f027d7fae4d702e:/sdk/python/arvados/util.py

diff --git a/sdk/python/arvados/util.py b/sdk/python/arvados/util.py
index 7148b9295b..d5ea18ba49 100644
--- a/sdk/python/arvados/util.py
+++ b/sdk/python/arvados/util.py
@@ -7,6 +7,8 @@ import errno
 import sys
 from arvados.collection import *
 
+HEX_RE = re.compile(r'^[0-9a-fA-F]+$')
+
 def clear_tmpdir(path=None):
     """
     Ensure the given directory (or TASK_TMPDIR if none given)
@@ -28,7 +30,10 @@ def run_command(execargs, **kwargs):
     kwargs.setdefault('close_fds', True)
     kwargs.setdefault('shell', False)
     p = subprocess.Popen(execargs, **kwargs)
-    stdoutdata, stderrdata = p.communicate(None)
+    if kwargs['stdout'] == subprocess.PIPE:
+        stdoutdata, stderrdata = p.communicate(None)
+    else:
+        p.wait()
     if p.returncode != 0:
         raise errors.CommandFailedError(
             "run_command %s exit %d:\n%s" %
@@ -160,7 +165,7 @@ def zipball_extract(zipball, path):
                     break
                 zip_file.write(buf)
             zip_file.close()
-            
+
             p = subprocess.Popen(["unzip",
                                   "-q", "-o",
                                   "-d", path,
@@ -306,3 +311,25 @@ def listdir_recursive(dirname, base=None):
         else:
             allfiles += [ent_base]
     return allfiles
+
+def is_hex(s, *length_args):
+    """is_hex(s[, length[, max_length]]) -> boolean
+
+    Return True if s is a string of hexadecimal digits.
+    If one length argument is given, the string must contain exactly
+    that number of digits.
+    If two length arguments are given, the string must contain a number of
+    digits between those two lengths, inclusive.
+    Return False otherwise.
+    """
+    num_length_args = len(length_args)
+    if num_length_args > 2:
+        raise ArgumentError("is_hex accepts up to 3 arguments ({} given)".
+                            format(1 + num_length_args))
+    elif num_length_args == 2:
+        good_len = (length_args[0] <= len(s) <= length_args[1])
+    elif num_length_args == 1:
+        good_len = (len(s) == length_args[0])
+    else:
+        good_len = True
+    return bool(good_len and HEX_RE.match(s))