fixed : better error message when dictionary missing

during benchmark.
Also : refactored ZSTD_fillHashTable(),
just for readability (it does the same thing)

programs/benchzstd.c

@@ -25,6 +25,7 @@
 #include <stdlib.h>      /* malloc, free */
 #include <string.h>      /* memset */
 #include <stdio.h>       /* fprintf, fopen */
+#include <errno.h>
 #include <assert.h>      /* assert */
 
 #include "benchfn.h"
@@ -799,6 +800,11 @@ BMK_benchOutcome_t BMK_benchFilesAdvanced(
     /* Load dictionary */
     if (dictFileName != NULL) {
         U64 const dictFileSize = UTIL_getFileSize(dictFileName);
+        if (dictFileSize == UTIL_FILESIZE_UNKNOWN) {
+            DISPLAYLEVEL(1, "error loading %s : %s \n", dictFileName, strerror(errno));
+            free(fileSizes);
+            RETURN_ERROR(9, BMK_benchOutcome_t, "benchmark aborted");
+        }
         if (dictFileSize > 64 MB) {
             free(fileSizes);
             RETURN_ERROR(10, BMK_benchOutcome_t, "dictionary file %s too large", dictFileName);

programs/fileio.c

@@ -487,6 +487,7 @@ static size_t FIO_createDictBuffer(void** bufferPtr, const char* fileName)
     DISPLAYLEVEL(4,"Loading %s as dictionary \n", fileName);
     fileHandle = fopen(fileName, "rb");
     if (fileHandle==NULL) EXM_THROW(31, "%s: %s", fileName, strerror(errno));
+
     fileSize = UTIL_getFileSize(fileName);
     if (fileSize > DICTSIZE_MAX) {
         EXM_THROW(32, "Dictionary file %s is too large (> %u MB)",
@@ -495,7 +496,7 @@ static size_t FIO_createDictBuffer(void** bufferPtr, const char* fileName)
     *bufferPtr = malloc((size_t)fileSize);
     if (*bufferPtr==NULL) EXM_THROW(34, "%s", strerror(errno));
     {   size_t const readSize = fread(*bufferPtr, 1, (size_t)fileSize, fileHandle);
-        if (readSize!=fileSize)
+        if (readSize != fileSize)
             EXM_THROW(35, "Error reading dictionary file %s : %s",
                     fileName, strerror(errno));
     }