On 10/21/2009 11:31 PM, Lucas Meneghel Rodrigues wrote:
Some distributors ship CD and DVD files with SHA1 hash sums instead
of MD5 hash sums, so let's extend the kvm_utils functions to
evaluate and compare SHA1 hashes:
* sha1sum_file(): Calculate SHA1 sum for file
+def sha1sum_file(filename, size=None):
+ """
+ Calculate the sha1sum of filename.
+ If size is not None, limit to first size bytes.
+ Throw exception if something is wrong with filename.
+ Can be also implemented with bash one-liner (assuming size%1024==0):
+ dd if=filename bs=1024 count=size/1024 | sha1sum -
+
+ @param filename: Path of the file that will have its sha1sum calculated.
+ @param returns: sha1sum of the file.
+ """
+ chunksize = 4096
+ fsize = os.path.getsize(filename)
+ if not size or size>fsize:
+ size = fsize
+ f = open(filename, 'rb')
+ o = sha.new()
+ while size> 0:
+ if chunksize> size:
+ chunksize = size
+ data = f.read(chunksize)
+ if len(data) == 0:
+ logging.debug("Nothing left to read but size=%d" % size)
+ break
+ o.update(data)
+ size -= len(data)
+ f.close()
+ return o.hexdigest()
+
This code and md5sum_file can share code.
Just pass o (or hash_new func: sha.new/md5.new) as a parameter to the function.
+
+
+def get_hash_from_file(sha_path, dvd_basename):
For consistency, replace sha_path with hash_path (as in the comment below).
+ """
+ Get the a hash from a given DVD image from a hash file
+ (Hash files are usually named MD5SUM or SHA1SUM and are located inside the
+ download directories of the DVDs)
+
+ @param hash_path: Local path to a hash file.
+ @param cd_image: Basename of a CD image
+ """
+ hash_file = open(sha_path, 'r')
+ for line in hash_file.readlines():
+ if dvd_basename in line:
+ return line.split()[0]
+
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