remove some -Wsign-compare warnings

diff --git a/lib/cgraph/agerror.c b/lib/cgraph/agerror.c
index baf9e1723f965586782d3f5761e3da4fd05aa2f9..a0cbb7f656274b34fa49421346bc36a45a7dc0b7 100644 (file)
--- a/lib/cgraph/agerror.c
+++ b/lib/cgraph/agerror.c
@@ -39,16 +39,12 @@ agerrlevel_t agseterr(agerrlevel_t lvl)
 
 char *aglasterr()
 {
-    long endpos;
-    long len;
-    char *buf;
-
     if (!agerrout)
        return 0;
     fflush(agerrout);
-    endpos = ftell(agerrout);
-    len = endpos - aglast;
-    buf = malloc(len + 1);
+    long endpos = ftell(agerrout);
+    size_t len = (size_t)(endpos - aglast);
+    char *buf = malloc(len + 1);
     fseek(agerrout, aglast, SEEK_SET);
     fread(buf, sizeof(char), len, agerrout);
     buf[len] = '\0';