From eaa62fa6d366727ab4f6c37f6c1be625560b5840 Mon Sep 17 00:00:00 2001
From: JaiLuthra1 <luthrajaiji@gmail.com>
Date: Tue, 28 Jan 2020 23:58:32 +0530
Subject: [PATCH] pdftops: added handling of empty input

---
 Makefile.am      | 13 ++++++++++---
 filter/pdf.cxx   | 18 ++++++++++++++++++
 filter/pdf.h     |  1 +
 filter/pdftops.c | 40 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 69 insertions(+), 3 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index 43f7a54e8..cc623cc68 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -789,10 +789,17 @@ texttotext_DEPENDENCIES = $(STRCASESTR)
 pdftops_SOURCES = \
 	filter/common.c \
 	filter/common.h \
-	filter/pdftops.c
+	filter/pdftops.c \
+	filter/pdf.cxx \
+	filter/pdf.h
 EXTRA_pdftops_SOURCES = filter/strcasestr.c
-pdftops_CFLAGS = $(CUPS_CFLAGS)
-pdftops_LDADD = $(STRCASESTR) $(CUPS_LIBS)
+pdftops_CFLAGS = \
+	$(CUPS_CFLAGS) \
+	$(LIBQPDF_CFLAGS)
+pdftops_LDADD = \
+	$(STRCASESTR) \
+	$(CUPS_LIBS) \
+	$(LIBQPDF_LIBS)
 pdftops_DEPENDENCIES = $(STRCASESTR)
 
 pdftoraster_SOURCES = \
diff --git a/filter/pdf.cxx b/filter/pdf.cxx
index f12607f86..175df2151 100644
--- a/filter/pdf.cxx
+++ b/filter/pdf.cxx
@@ -84,6 +84,24 @@ extern "C" void pdf_free(pdf_t *pdf)
   delete pdf;
 }
 
+/*
+ * 'pdf_pages()' - Count number of pages in file
+ *                         using QPDF.
+ * I - Filename to open
+ * O - Number of pages or -1 on error
+ */
+int pdf_pages(const char *filename)
+{
+  QPDF *pdf = new QPDF();
+  try{
+  pdf->processFile(filename);
+  }catch(...) {
+    return -1;
+  }
+  int pages = (pdf->getAllPages()).size();
+  return pages;
+}
+
 
 /**
  * 'pdf_prepend_stream' - Prepend a stream to the contents of a specified
diff --git a/filter/pdf.h b/filter/pdf.h
index 18dcfa90b..eaaf1903f 100644
--- a/filter/pdf.h
+++ b/filter/pdf.h
@@ -45,6 +45,7 @@ void pdf_add_type1_font(pdf_t *doc, unsigned page, const char *name);
 void pdf_resize_page(pdf_t *doc, unsigned page, float width, float length, float *scale);
 void pdf_duplicate_page (pdf_t *doc, unsigned page, unsigned count);
 int pdf_fill_form(pdf_t *doc, opt_t *opt);
+int pdf_pages(const char *filename);
 
 #ifdef __cplusplus
 }
diff --git a/filter/pdftops.c b/filter/pdftops.c
index 2ff74c6c4..8444e81f5 100644
--- a/filter/pdftops.c
+++ b/filter/pdftops.c
@@ -23,6 +23,7 @@
  * Include necessary headers...
  */
 
+#include "pdf.h"
 #include <config.h>
 #include <cups/cups.h>
 #include <cups/ppd.h>
@@ -224,6 +225,42 @@ void remove_options(char *options_str, const char **option_list)
 }
 
 
+/*
+ * Check whether given file is empty
+ */
+
+int is_empty(char *filename)
+{
+  FILE *fp = NULL;
+  fp = fopen(filename, "rb");
+  if (fp == NULL)
+  {
+    fprintf(stderr, "ERROR: pdftops - cannot open print file \"%s\"\n",
+            filename);
+    exit(1);
+  }
+  else
+  {
+    char buf[1];
+    rewind(fp);
+    if (fread(buf, 1, 1, fp) == 0) {
+      fclose(fp);
+      fprintf(stderr, "DEBUG: Input is empty, outputting empty file.\n");
+      return 1;
+    }
+    fclose(fp);
+    int pages = pdf_pages(filename);
+    if (pages == 0) {
+      fprintf(stderr, "DEBUG: No pages left, outputting empty file.\n");
+      return 1;
+    }
+    if (pages > 0)
+      return 0;
+    exit(1);
+  }
+}
+
+
 /*
  * Before calling any command line utility, log its command line in CUPS'
  * debug mode
@@ -381,6 +418,9 @@ main(int  argc,				/* I - Number of command-line args */
     tempfile[0] = '\0';
   }
 
+  if (is_empty(filename))
+    return 0;
+
  /*
   * Read out copy counts and collate setting passed over by pdftopdf
   */
-- 
2.47.2