cf-serverd now stats file every read on network transmission

Previously the file was `stat`'ed every N read to detect file changes during transmission. The reason for limiting the calls to stat is probably to make the code more efficient. However, there are reasons to believe that the bug experienced in ENT-12033 is attributed to filechanges during transmission. Hence, I'm changing the code to do this for every read, as it better to be safe and happy rather than fast but sorry. Yes, `stat()` is a system call. However, it has pretty good cashing mechanisms on modern systems. So it should not be too expensive. Ticket: None Changelog: None Signed-off-by: Lars Erik Wik <[email protected]>
cfengine · Oct 28, 2024 · 3856d02 · 3856d02
1 parent f58d612
commit 3856d02
Showing 1 changed file with 5 additions and 15 deletions.
diff --git a/cf-serverd/server_common.c b/cf-serverd/server_common.c
@@ -403,7 +403,7 @@ static void FailedTransfer(ConnectionInfo *connection)
 void CfGetFile(ServerFileGetState *args)
 {
     int fd;
-    off_t n_read, total = 0, sendlen = 0, count = 0;
+    off_t n_read, total = 0, sendlen = 0;
     char sendbuffer[CF_BUFSIZE + 256], filename[CF_BUFSIZE - 128];
     struct stat sb;
     int blocksize = 2048;
@@ -459,13 +459,6 @@ void CfGetFile(ServerFileGetState *args)
     }
     else
     {
-        int div = 3;
-
-        if (sb.st_size > 10485760L) /* File larger than 10 MB, checks every 64kB */
-        {
-            div = 32;
-        }
-
         while (true)
         {
             memset(sendbuffer, 0, CF_BUFSIZE);
@@ -488,14 +481,11 @@ void CfGetFile(ServerFileGetState *args)
 
                 /* check the file is not changing at source */
 
-                if (count++ % div == 0)   /* Don't do this too often */
+                if (stat(filename, &sb) == -1)
                 {
-                    if (stat(filename, &sb))
-                    {
-                        Log(LOG_LEVEL_ERR, "Cannot stat file '%s'. (stat: %s)",
-                            filename, GetErrorStr());
-                        break;
-                    }
+                    Log(LOG_LEVEL_ERR, "Cannot stat file '%s'. (stat: %s)",
+                        filename, GetErrorStr());
+                    break;
                 }
 
                 if (sb.st_size != savedlen)