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.

diff --git a/rc/bin/hget b/rc/bin/hget
index dca3c15228b99fe6bab1d1d913a36508d2253192..ce258575bbf0977643f14e62018b6c978c471fa8 100755 (executable)
--- 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)