[open] add some more checks when opening a file

src/lnav_commands.cc

@@ -878,11 +878,19 @@ static string com_open(string cmdline, vector<string> &args)
                 retval = "info: watching -- " + fn;
             }
             else if (stat(fn.c_str(), &st) == -1) {
-                retval = "error: cannot stat file: " + fn + " " + strerror(errno);
+                retval = ("error: cannot stat file: " + fn + " -- "
+                    + strerror(errno));
             }
             else if ((abspath = realpath(fn.c_str(), NULL)) == NULL) {
                 retval = "error: cannot find file";
             }
+            else if (!S_ISREG(st.st_mode)) {
+                retval = "error: not a regular file";
+            }
+            else if (access(fn.c_str(), R_OK) == -1) {
+                retval = (string("error: cannot read file -- ") +
+                    strerror(errno));
+            }
             else {
                 fn = abspath.in();
                 lnav_data.ld_file_names.insert(make_pair(fn, -1));

test/test_cmds.sh

@@ -98,6 +98,19 @@ check_output "open is not working" <<EOF
 EOF
 
 
+run_test ${lnav_test} -n \
+    -c ":close" \
+    -c ":open /" \
+    ${test_dir}/logfile_access_log.0
+
+check_error_output "open dir is working" <<EOF
+error: not a regular file
+EOF
+
+check_output "open dir is not working" <<EOF
+EOF
+
+
 run_test ${lnav_test} -n \
     -c ";select * from access_log" \
     -c ':write-json-to -' \