scripts/functions: add aria2, a powerfull downloader

aria2 is a powerfull downloader that is capable of chunking and
parallel retrieval.

Due to li;itations in crosstool-NG retrieval facilities, it's not possible
to take fully advantage of aria2. It might happen that, in the future,
those limitations get lifted away, so we can take use features such as
parallel downloading from more than one server at the same time. For now,
it should still speed up downloads thanks to parallel downloading of chunks.

1 files changed, 16 insertions, 1 deletions

diff --git a/config/global/download.in b/config/global/download.in
index 7a4cf48..fd651cb 100644
--- a/config/global/download.in
+++ b/config/global/download.in
@@ -89,7 +89,7 @@ endif # USE_MIRROR
 
 config CONNECT_TIMEOUT
     int
-    prompt "connection timeout"
+    prompt "Connection timeout"
     default 10
     help
       From the curl manual:
@@ -109,6 +109,21 @@ config CONNECT_TIMEOUT
       
       Note that this value applies equally to wget if you have that installed.
 
+config DOWNLOAD_MAX_CHUNKS
+    int
+    prompt "Maximum number of // chunks"
+    default 5
+    range 1 10
+    help
+      If you have aria2 installed, then it will be used to download files.
+      Aria2 can split the download in chunks, and download those chunks in //
+      which can be interesting to speed up the download.
+      
+      On the other hand, using many chunks, or even chunking in general, may
+      be seen by some site admins as being kind of unfair, or even as a DoS.
+      That's why the range of acceptable values is [1..10], and the default
+      is 5 (aria2's default).
+
 config ONLY_DOWNLOAD
     bool
     prompt "Stop after downloading tarballs"