hghave: detect FIFO availability

tests/hghave

@@ -1,55 +1,59 b''
 #!/usr/bin/env python
 """Test the running system for features availability. Exit with zero
 if all features are there, non-zero otherwise.
 """
 import optparse
 import os
 import sys
 
 def has_symlink():
     return hasattr(os, "symlink")
 
+def has_fifo():
+    return hasattr(os, "mkfifo")
+
 checks = {
     "symlink": (has_symlink, "symbolic links"),
+    "fifo": (has_fifo, "named pipes"),
 }
 
 def list_features():
     for name, feature in checks.iteritems():
         desc = feature[1]
         print name + ':', desc
 
 parser = optparse.OptionParser("%prog [options] [features]")
 parser.add_option("--list-features", action="store_true",
                   help="list available features")
 parser.add_option("-q", "--quiet", action="store_true",
                   help="check features silently")
 
 if __name__ == '__main__':
     options, args = parser.parse_args()
     if options.list_features:
         list_features()
         sys.exit(0)
         
     quiet = options.quiet
 
     failures = 0
 
     def error(msg):
         global failures
         if not quiet:
             sys.stderr.write(msg + '\n')
         failures += 1
     
     for feature in args:
         if feature not in checks:
             error('hghave: unknown feature: ' + feature)
             continue
         
         check, desc = checks[feature]       
         if not check():
             error('hghave: missing feature: ' + desc)
 
     if failures != 0:
         sys.exit(1)