Message MD5 generation

Question

Hi all,

for my ROS project I need to get MD5 checksum of messages from their .msg files. Following documentation this should be quite simple. I just get the .msg file with:

• comments and whitespace removed;
• package names of dependencies removed;
• constants reordered ahead of other declarations;
• MD5 text of dependency concatenated,

and calculate MD5 on it.

So, for std_msgs/String, the MD5 should be calculated on:

stringdata

and the MD5 be:

cb6d1e784571bbf6f218efb801675fb6

Instead the generated message in my Hydro installation has MD5 (rosmsg md5 std_msgs/String):

992ce8a1687cec8c8bd883ec73ca41d1

Can one help me to understand what is wrong?

Thanks a lot Alessandro

EDITED

See https://github.com/ros/genmsg/blob/indigo-devel/src/genmsg/gentools.py and https://github.com/ros/genmsg/blob/indigo-devel/src/genmsg/msgs.py

Thanks to gvdhorn!

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Originally posted by afranceson on ROS Answers with karma: 497 on 2015-01-21

Post score: 1

Answer 1

Not a real answer, but have you perhaps considered using genmsg for this? See genmsg/test/test_genmsg_gentools.py for some examples.

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Edit: just to be complete:

msg_context = genmsg.msg_loader.MsgContext.create_default()
full_type_name = genmsg.gentools.compute_full_type_name(package_name, os.path.basename(input_file))
spec = genmsg.msg_loader.load_msg_from_file(msg_context, input_file, full_type_name)
search_path = genmsg.command_line.includepath_to_dict(include_path)
genmsg.msg_loader.load_depends(msg_context, spec, search_path)
md5sum = genmsg.gentools.compute_md5(msg_context, spec)

Mostly creative copy/paste from the genmsg package.

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Originally posted by gvdhoorn with karma: 86574 on 2015-01-21

This answer was ACCEPTED on the original site

Post score: 0

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Original comments

Comment by gvdhoorn on 2018-06-09:
Update: rosmg md5 $pkg/$msg should also work.