hget: do a HEAD request to check if the file is already complete (thanks miscief)

when we continue a download, make sure the file isnt already
complete, as otherwise the server might respond with a 416
as the range request will out of range.

1 files changed, 13 insertions, 2 deletions

diff --git a/rc/bin/hget b/rc/bin/hget
index dca3c1522..ce258575b 100755
--- a/rc/bin/hget
+++ b/rc/bin/hget
@@ -47,13 +47,24 @@ if(! ~ $#o 0){
 	if(test -s $o)
 		s=`{ls -l $o | awk '{print $6}'}
 }
-if(! ~ $s 0)
-	r=($r 'Range: bytes='^$s^'-')
 <[3=0] <>/mnt/web/clone {
 	d=/mnt/web/^`{sed 1q}
 	if(~ $#b 1)
 		echo -n baseurl $b >[1=0]
 	echo -n url $1 >[1=0]
+	if(! ~ $s 0 && ~ $#p 0 && ~ $#P 0 && ~ $#m 0){
+		for(i in $r)
+			echo -n headers $i >[1=0]
+		echo -n request HEAD >[1=0]
+		<$d/body {
+			if(~ $s `{cat $d/contentlength >[2]/dev/null})       
+				exit ''
+		}
+		if(~ $#b 1)
+			echo -n baseurl $b >[1=0]
+		echo -n url $1 >[1=0]
+		r=($r 'Range: bytes='^$s^'-')
+	}
 	for(i in $r)
 		echo -n headers $i >[1=0]
 	if(~ $#m 1)