Fix PDF validation

src/utils/pdf_utils.rs

@@ -2,17 +2,22 @@
 //!
 //! @author Pierre Hubert
 
+use pdf::backend::Backend;
+
 use crate::data::error::{ExecError, ResultBoxError};
 
 /// Check out whether a PDF is a valid PDF or not, by trying to open it
 pub fn is_valid_pdf(file: &bytes::Bytes) -> ResultBoxError<bool> {
-    let pdf = pdf::file::File::new(Vec::from(file.as_ref()));
+    let backend = file.to_vec();
 
-    match pdf.get_num_pages() {
-        Ok(num) if num < 1 =>
-            Err(ExecError::boxed_string(format!("Detected a PDF with {} pages!", num))),
-
-        Ok(_) => Ok(true),
+    match backend.read_xref_table_and_trailer() {
+        Ok((refs, _)) => {
+            if refs.is_empty() {
+                Err(ExecError::boxed_string(format!("Detected a PDF with 0 references (file size: {})!", file.len())))
+            } else {
+                Ok(true)
+            }
+        }
 
         Err(e) => {
             println!("Error while parsing PDF: {}", e);