Bug#422088: [Patch] wish preseed_fetch could distinguish between non-existance of a requested file and other failures to fetch file.

["Alex Owen" <r.alex.owen@gmail.com>]

Package: preseed-common
Severity: wishlist
Version: 1.29

Attached is a patch against d-i SVN trunk so that file_preseed can
distinuish between a failure to fetch a file because it does not exist
and any other failure.

If a file does not exist then exit status is 4 otherwise it is 1.
I chose 4 as shorthand for HTTP 404 error.

This should be backwards compatable with existing code that just
checks for sucsess/fail.
New code (I'm thinking custom preseed systems here) can then pase the
exit code.

A custom preseed setup could have 2 dirs such as:
$base/standard
$base/local

a master preseed script could then try to do
 "preseed_fetch $base/local/script"
and if this exits with status 4 fall back to
 "preseed_fetch $base/standard/script"

If some other failure occurs the master preseed script can act accordingly.
I'm thinking of the "Hands-Off" preseed system here.

Feel free to change the exit code 4 to someother non-zero value if you will!
I'm afraid this code is as yet untested.

Regards

Alex Owen

Index: preseed/fetch-methods/file
===================================================================
--- preseed/fetch-methods/file	(revision 46683)
+++ preseed/fetch-methods/file	(working copy)
@@ -1,6 +1,8 @@
 protocol_fetch() {
 	FILE="${1#file://*}"
-	if [ ! -e "$FILE" ] || ! cp "$FILE" $2; then
+	if [ ! -e "$FILE" ] ; then
+		return 4
+	elif ! cp "$FILE" $2; then
 		return 1
 	else
 		return 0
Index: preseed/fetch-methods/http
===================================================================
--- preseed/fetch-methods/http	(revision 46683)
+++ preseed/fetch-methods/http	(working copy)
@@ -1,6 +1,7 @@
 protocol_fetch() {
 	local url="$1"
 	local file="$2"
+	local log=/tmp/preseed_fetch_http
 	iters=0
 
 	# use the proxy for wgets (should speed things up)
@@ -10,10 +11,15 @@
 
 	while [ $iters -lt 3 ]; do
 		# TODO add progress bar
-		if wget -q "$url" -O "$file"; then
+		if wget -q "$url" -O "$file" 2>$log ; then
+			rm -f $log
 			return 0
+		elif	grep "server returned error 404" $log >/dev/null ; then
+			rm -f $log
+			return 4			
 		fi
 		iters=$(($iters + 1))
 	done
+	rm -f $log
 	return 1
 }
Index: preseed/fetch-methods/floppy
===================================================================
--- preseed/fetch-methods/floppy	(revision 46683)
+++ preseed/fetch-methods/floppy	(working copy)
@@ -4,7 +4,9 @@
 	mountfloppy || true
 	touch /var/run/preseed-usedfloppy
         
-	if [ ! -e "$FILE" ] || ! cp "$FILE" $2; then
+	if [ ! -e "$FILE" ] ; then
+		return 4
+	elif ! cp "$FILE" $2; then
 		return 1
 	else
 		return 0