[logfile] a captured file cannot be overwritten

Fixes #741

src/logfile.cc

@@ -91,6 +91,7 @@ logfile::logfile(const string &filename, logfile_open_options &loo)
     }
     else {
         log_perror(fstat(this->lf_options.loo_fd, &this->lf_stat));
+        this->lf_named_file = false;
         this->lf_valid_filename = false;
     }
 
@@ -298,9 +299,10 @@ logfile::rebuild_result_t logfile::rebuild_index()
     }
 
     // Check the previous stat against the last to see if things are wonky.
-    if (st.st_size < this->lf_stat.st_size ||
+    if (this->lf_named_file &&
+        (st.st_size < this->lf_stat.st_size ||
          (this->lf_stat.st_size == st.st_size &&
-         this->lf_stat.st_mtime != st.st_mtime)) {
+          this->lf_stat.st_mtime != st.st_mtime))) {
         log_info("overwritten file detected, closing -- %s  new: %" PRId64
                      "/%" PRId64 "  old: %" PRId64 "/%" PRId64,
                  this->lf_filename.c_str(),

src/logfile.hh

@@ -377,6 +377,7 @@ protected:
 
     logfile_open_options lf_options;
     logfile_activity lf_activity;
+    bool        lf_named_file{true};
     bool        lf_valid_filename;
     std::string lf_filename;
     std::string lf_basename;

test/test_logfile.sh

@@ -1,6 +1,15 @@
 #! /bin/bash
 
 
+echo "Hi" | run_test ${lnav_test} -d /tmp/lnav.err -nt -w logfile_stdin.0.log \
+    -c ':shexec sleep 1 && touch -t 200711030923 logfile_stdin.0.log'
+
+check_output "piping to stdin is not working?" <<EOF
+2013-06-06T12:13:20.123  Hi
+2013-06-06T12:13:20.123  ---- END-OF-STDIN ----
+EOF
+
+
 cp ${srcdir}/logfile_syslog.0 truncfile.0
 chmod u+w truncfile.0