[Bug-wget] [Patch] Regression: write error on wget -c for already fully retrieved file

[Torsten Scheck]

Dear wget community,

the Yocto Project's sanity checks for connectivity fail on Debian unstable,
as the current wget -c reports a write error for an already fully retrieved
file. (Yocto is an OpenEmbedded-based system builder suite.)

This issue might depend on server behaviour, so please test with the URL
provided below.

Steps to reproduce:

1. Download file from yocto server
$ wget 'https://eula-downloads.yoctoproject.org/index.php'
...
2012-11-13 19:23:37 (146 KB/s) - ‘index.php’ saved [105711]

2. Download same file from yocto server with -c
$ wget -c 'https://eula-downloads.yoctoproject.org/index.php'
...
Cannot write to ‘index.php’ (Resource temporarily unavailable).
$ echo $?
3

Expected behaviour:

"The file is already fully retrieved; nothing to do."
status code: 0


I used "git bisect" and found the following commit as culprit:

-----------------------8<-------------------------8<----------------------
commit 954fead685de2cc972552ed1b294a84845cf638a
Author: Alan Jenkins <address@hidden>
Date:   Tue Jul 20 19:42:13 2010 +0200

    Fix a failure if the server doesn't specify a content-length and -c is
used.
-----------------------8<-------------------------8<----------------------


When I undo this commit's change in the current master branch, wget works
as expected for my use case.

-----------------------8<-------------------------8<----------------------
diff --git a/src/http.c b/src/http.c
index 5888474..1a4ccda 100644
--- a/src/http.c
+++ b/src/http.c
@@ -2690,7 +2690,7 @@ read_header:

   if (statcode == HTTP_STATUS_RANGE_NOT_SATISFIABLE
       || (!opt.timestamping && hs->restval > 0 && statcode == HTTP_STATUS_OK
-          && contrange == 0 && contlen >= 0 && hs->restval >= contlen))
+          && contrange == 0 && hs->restval >= contlen))
     {
       /* If `-c' is in use and the file has been fully downloaded (or
          the remote file has shrunk), Wget effectively requests bytes
-----------------------8<-------------------------8<----------------------


But Mr. Alan Jenkins surely had a use case which he had fixed with his
commit. Are there any regression tests which I can run?

I would be nice if wget were able to work for all use cases.
Please have a look in this issue, if you're a wget maintainer.

Cheers,
Torsten Scheck


-- 
Torsten Scheck <address@hidden>  Jabber:address@hidden
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software engineer:open standards/access/knowledge:enthgnusiast