Tools: Print hint about product when wrong tool used

tests/bufr_get.sh

@@ -119,6 +119,25 @@ result=`${tools_dir}/bufr_get -p unpack:d,heightOfStation aaen_55.bufr`
 result=`${tools_dir}/bufr_get -p unpack:s,heightOfStation aaen_55.bufr`
 [ "$result" = "0 858000" ]
 
+# ----------------------------------------
+# Wrong message type
+# ----------------------------------------
+f=$data_dir/sample.grib2
+set +e
+${tools_dir}/bufr_get -p edition $f > $fLog 2>&1
+status=$?
+set -e
+[ $status -ne 0 ]
+grep -q "Input file seems to be GRIB" $fLog
+
+f=$ECCODES_SAMPLES_PATH/budg.tmpl
+set +e
+${tools_dir}/bufr_get -p edition $f > $fLog 2>&1
+status=$?
+set -e
+[ $status -ne 0 ]
+grep -q "Input file seems to be GRIB" $fLog
+
 
 # ----------------------------------------
 # Unreadable message

tests/grib_get_fail.sh

@@ -88,5 +88,16 @@ grep -q "unreadable message" $tempText
 rm -f $outfile
 
 
+# ----------------------
+# Wrong message type
+# ----------------------
+set +e
+${tools_dir}/grib_get -p edition $ECCODES_SAMPLES_PATH/BUFR3.tmpl > $tempText 2>&1
+status=$?
+set -e
+[ $status -ne 0 ]
+grep -q "Input file seems to be BUFR" $tempText
+
+
 # Clean up
 rm -f $tempText

tools/grib_tools.cc

@@ -10,6 +10,7 @@
 
 #include "grib_tools.h"
 #include <stdlib.h>
+#include <string>
 
 #if HAVE_LIBJASPER
 /* Remove compiler warnings re macros being redefined */
@@ -308,6 +309,29 @@ static int grib_tool_with_orderby(grib_runtime_options* options)
 
 static char iobuf[1024 * 1024];
 
+// Read the first few bytes of the file to guess what kind of product
+// it could be. Returns an empty string if it fails
+static std::string guess_file_product(const std::string& filename)
+{
+    std::string result;
+    char buffer[5] = {0,};
+    FILE* fin = fopen(filename.c_str(), "rb");
+    if (fin) {
+        size_t bytes = fread(buffer, 1, sizeof(buffer), fin);
+        if (bytes == sizeof(buffer)) {
+            if (strncmp(buffer, "GRIB", 4)==0) {
+                result = "GRIB";
+            } else if (strncmp(buffer, "BUDG", 4)==0) {
+                result = "GRIB";
+            } else if (strncmp(buffer, "BUFR", 4)==0) {
+                result = "BUFR";
+            }
+        }
+        fclose(fin);
+    }
+    return result;
+}
+
 static int grib_tool_without_orderby(grib_runtime_options* options)
 {
     int err = 0;
@@ -419,6 +443,10 @@ static int grib_tool_without_orderby(grib_runtime_options* options)
 
         if (infile->handle_count == 0) {
             fprintf(stderr, "%s: No messages found in %s\n", tool_name, infile->name);
+            std::string product = guess_file_product(infile->name);
+            if (!product.empty()) {
+                fprintf(stderr, "%s: Input file seems to be %s\n", tool_name, product.c_str());
+            }
             if (options->fail)
                 exit(1);
         }