use magic numbers to dectect filetypes

1 files changed, 9 insertions, 12 deletions

diff --git a/pdftool.pl b/pdftool.pl
index b5f897d..a0566a4 100755
--- a/pdftool.pl
+++ b/pdftool.pl
@@ -436,25 +436,22 @@ sub pdftops {
     #
     # To avoid to seek into IN, it gonna be copied from WRITE to READ in
     # the background, once the filetype has been read
-    #
-    # TODO: read specifications, to properly detect the filetype
 
     my $filetype;
     my ($READ, $WRITE);
     pipe $READ, $WRITE  or  die "Cannot pipe: $!";
 
-    while (not (defined $filetype) && defined (my $l = <$IN>)) {
-        print $WRITE ($l)  or  die "Cannot print: $!";
-
-        if (defined $l && $l =~ /^%!PS/) {
-            $filetype = "PS";
-        } elsif (defined $l && $l =~ /^%PDF/) {
-            $filetype = "PDF";
-        }
+    # Detect the file type of the input file from its magic number
+    $_ = <$IN>;
+    print $WRITE ($_)  or  die "Cannot print: $!";
+    if (defined $_ && $_ =~ /^%!/) {
+        $filetype = "PS";
+    } elsif (defined $_ && $_ =~ /^%PDF/) {
+        $filetype = "PDF";
+    } else {
+        die "Error: Input file has an unknown magic number.\n";
     }
 
-    die "Cannot recognize the filetype.\n"  unless  defined $filetype;
-
     unless (my $pid = fork) {
         # Child: cat $IN > $WRITE in background
         die "Cannot fork: $!" unless defined $pid;