On Mon, 16 Mar 2015, Leon Winter wrote:
The basic problem is that curl (the binary) opens the file very early
without any knowledge of the server response. This also leads to another
bug/inconsistency. The effective URL does not need to match the effective
filename since the filename is statically computed from the input URL and
not from the effective URL (which can be different due to 3xx HTTP
redirections).
Nice work Leon!
My first gut reaction: I don't think we are "allowed" to change what file name
-O uses unless you also use -J. I mean, your logic and work so far is great
but I think -O should get the file name from the initial URL while you're
allowed or even encouraged to figure out the "right" name with -J.
This because with -J a user cannot fully know which file name that will be
used but with -O (without -J) the URL clearly tells which file name that will
end up on the disk after a succesful transfer and there is bound to exist many
scripts out there relying on its behavior. Even with redirects.
Or am I being unreasonable?
However this patch is still work-in-progress as it does not solve the key
problem of #81 which is to actually resume the download. The patch however
gets the "right" file, yet does not resume the download. This is because
when we do the initial first request we do not know the output file name and
thus cannot determine the filesize of our local file.
I'm pretty sure we should just document this as a known limitation somewhere
(probably documented nearby -J) as I believe chasing after a solution to this
is going to lure us into dark and scary places of guesses and assumptions.
Regarding the code in the patch I am not to sure about my check for the
"Location" header response field or whether one can perform this check in a
better way.
I think that's a decent way. You can also just opt to parse incoming headers
and check the HTTP response code for relevant 3xx codes.
Also while testing I just noticed there are problems when doing a HEAD
request (curl -I):
I am not sure why there is an attempt to write to the file when I am just
doing a HEAD request though.
Hm. I'll try to give that a closer look soon.
--
/ daniel.haxx.se
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