netlocker fixes

1 files changed, 63 insertions, 0 deletions

diff --git a/src/fnettrace/tail.c b/src/fnettrace/tail.c
new file mode 100644
index 000000000..a910788d6
--- /dev/null
+++ b/src/fnettrace/tail.c
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2014-2022 Firejail Authors
+ *
+ * This file is part of firejail project
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+#include "fnettrace.h"
+
+void tail(const char *logfile) {
+        assert(logfile);
+
+        // wait for no more than 5 seconds for the logfile to appear in the filesystem
+        int cnt = 5;
+        while (access(logfile, R_OK) && cnt > 0)
+                cnt--;
+        if (cnt == 0)
+                exit(1);
+
+        off_t last_size = 0;
+
+        while (1) {
+                int fd = open(logfile, O_RDONLY);
+                if (fd == -1)
+                        return;
+
+                off_t size = lseek(fd, 0, SEEK_END);
+                if (size < 0) {
+                        close(fd);
+                        return;
+                }
+
+                char *content = NULL;
+                int mmapped = 0;
+                if (size && size != last_size) {
+                        content = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
+                        close(fd);
+                        if (content != MAP_FAILED)
+                                mmapped = 1;
+                }
+
+                if (mmapped) {
+                        printf("%.*s", (int) (size - last_size), content + last_size);
+                        fflush(0);
+                        munmap(content, size);
+                        last_size = size;
+                }
+
+                sleep(1);
+        }
+}