Refs #7830 - Use simpler test for cURL.

Code/Tools/DOI/doi.py

@@ -294,34 +294,23 @@ def check_if_doi_exists(base, doi, destination, options):
             "Unexpected result back from server: \"" + result[0] + "\"")
 
 def check_for_curl():
-    '''A check to see whether we can call cURL on the command line.  Based on
-    an implementation of "which" found at http://stackoverflow.com/a/379535.
-    If cURL cannot be called an exception will be raised, else the script will
-    be free to continue.
-
-    This appears to work on both Linux and Windows.
+    '''A check to see whether we can call cURL on the command line.
     '''
-    def is_exe(fpath):
-        return os.path.exists(fpath) and os.access(fpath, os.X_OK)
-
-    def ext_candidates(fpath):
-        yield fpath
-        for ext in os.environ.get("PATHEXT", "").split(os.pathsep):
-            yield fpath + ext
-
-    fpath, fname = os.path.split("curl")
-    if fpath:
-        if is_exe("curl"):
-            return # Found cURL.
-    else:
-        for path in os.environ["PATH"].split(os.pathsep):
-            exe_file = os.path.join(path, "curl")
-            for candidate in ext_candidates(exe_file):
-                if is_exe(candidate):
-                    return # Found cURL.
-
-    raise Exception('This script requires that cURL be installed and ' + \
-                    'available on the PATH.')
+    # See if a call to 'curl --version' gives us a successful return code,
+    # else raise an exception.
+    try:
+        proc = subprocess.Popen(['curl', '--version'],stdout=subprocess.PIPE)
+        proc.wait()
+        if proc.returncode == 0:
+            found = True
+        else:
+            found = False
+    except:
+        found = False
+
+    if not found:
+        raise Exception('This script requires that cURL be installed and ' + \
+                        'available on the PATH.')
 
 def run(options):
     '''Creating a usable DOI is (for our purposes at least) a two step