From 75a5936924e2c65cf1f344946fe7c8a9d40ff2d9 Mon Sep 17 00:00:00 2001
From: Maria Matejka <mq@ucw.cz>
Date: Thu, 24 Aug 2023 15:38:44 +0200
Subject: [PATCH] Logging limit enforcement moved into the rfile structure

---
 sysdep/unix/config.Y |  4 ++--
 sysdep/unix/io.c     | 20 +++++++++++++++-----
 sysdep/unix/log.c    | 28 ++++++++++++++++------------
 sysdep/unix/unix.h   |  4 ++--
 4 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/sysdep/unix/config.Y b/sysdep/unix/config.Y
index 49aa8582..a9feec02 100644
--- a/sysdep/unix/config.Y
+++ b/sysdep/unix/config.Y
@@ -52,7 +52,7 @@ log_file:
    text log_limit {
      if (!parse_and_exit)
      {
-       this_log->rf = rf_open(new_config->pool, $1, RF_APPEND);
+       this_log->rf = rf_open(new_config->pool, $1, RF_APPEND, this_log->limit);
        if (!this_log->rf) cf_error("Unable to open log file '%s': %m", $1);
      }
      this_log->filename = $1;
@@ -91,7 +91,7 @@ mrtdump_base:
  | MRTDUMP text ';' {
      if (!parse_and_exit)
      {
-       struct rfile *f = rf_open(new_config->pool, $2, RF_APPEND);
+       struct rfile *f = rf_open(new_config->pool, $2, RF_APPEND, 0);
        if (!f) cf_error("Unable to open MRTDump file '%s': %m", $2);
        new_config->mrtdump_file = f;
      }
diff --git a/sysdep/unix/io.c b/sysdep/unix/io.c
index ff6f96af..faf759a5 100644
--- a/sysdep/unix/io.c
+++ b/sysdep/unix/io.c
@@ -67,6 +67,7 @@ struct rfile {
   resource r;
   struct stat stat;
   int fd;
+  off_t limit;
   _Atomic off_t pos;
 };
 
@@ -126,7 +127,7 @@ rf_stat(struct rfile *r)
 }
 
 struct rfile *
-rf_open(pool *p, const char *name, enum rf_mode mode)
+rf_open(pool *p, const char *name, enum rf_mode mode, off_t limit)
 {
   int fd = rf_open_get_fd(name, mode);
 
@@ -135,6 +136,7 @@ rf_open(pool *p, const char *name, enum rf_mode mode)
 
   struct rfile *r = ralloc(p, &rf_class);
   r->fd = fd;
+  r->limit = limit;
 
   switch (mode)
   {
@@ -168,12 +170,20 @@ rf_same(struct rfile *a, struct rfile *b)
     (a->stat.st_ino == b->stat.st_ino);
 }
 
-void
+int
 rf_write(struct rfile *r, const void *buf, size_t count)
 {
-  while ((write(r->fd, buf, count) < 0) && (errno == EINTR))
-    ;
-  atomic_fetch_add_explicit(&r->pos, count, memory_order_relaxed);
+  if (r->limit && (atomic_fetch_add_explicit(&r->pos, count, memory_order_relaxed) + (off_t) count > r->limit))
+  {
+    atomic_fetch_sub_explicit(&r->pos, count, memory_order_relaxed);
+    return 0;
+  }
+  else
+  {
+    while ((write(r->fd, buf, count) < 0) && (errno == EINTR))
+      ;
+    return 1;
+  }
 }
 
 
diff --git a/sysdep/unix/log.c b/sysdep/unix/log.c
index 87df4fc6..0c89ebd6 100644
--- a/sysdep/unix/log.c
+++ b/sysdep/unix/log.c
@@ -149,7 +149,7 @@ log_rotate(struct log_channel *lc)
   if ((rename(lc->filename, lc->backup) < 0) && (unlink(lc->filename) < 0))
     return lts_request(lc, NULL, "Log Rotate Failed");
 
-  struct rfile *rf = rf_open(log_pool, lc->filename, RF_APPEND);
+  struct rfile *rf = rf_open(log_pool, lc->filename, RF_APPEND, lc->limit);
   if (!rf)
     return lts_request(lc, NULL, "Log Rotate Failed");
 
@@ -196,19 +196,23 @@ log_commit(log_buffer *buf)
 	  *buf->buf.pos = '\n';
 	  byte *begin = l->terminal ? buf->buf.start : buf->tm_pos;
 	  off_t msg_len = buf->buf.pos - begin + 1;
-	  if (l->limit && (rf_size(rf) + msg_len > l->limit))
+	  do {
+	    if (rf_write(rf, buf->tm_pos, msg_len))
+	      break;
+
+	    log_lock();
+	    rf = atomic_load_explicit(&l->rf, memory_order_acquire);
+	    if (rf_write(rf, buf->tm_pos, msg_len))
 	    {
-	      log_lock();
-              rf = atomic_load_explicit(&l->rf, memory_order_acquire);
-	      if (rf_size(rf) + msg_len > l->limit)
-	      {
-		log_rotate(l);
-		rf = atomic_load_explicit(&l->rf, memory_order_relaxed);
-	      }
 	      log_unlock();
+	      break;
 	    }
 
-	  rf_write(l->rf, buf->tm_pos, msg_len);
+	    log_rotate(l);
+	    log_unlock();
+
+	    rf = atomic_load_explicit(&l->rf, memory_order_relaxed);
+	  } while (!rf_write(rf, buf->tm_pos, msg_len));
 	}
 #ifdef HAVE_SYSLOG_H
       else
@@ -470,7 +474,7 @@ log_switch(int initial, list *logs, const char *new_syslog_name)
       rmove(l->rf, log_pool);
     else if (l->filename)
     {
-      l->rf = rf_open(log_pool, l->filename, RF_APPEND);
+      l->rf = rf_open(log_pool, l->filename, RF_APPEND, l->limit);
       erf = l->rf ? 0 : errno;
     }
     log_unlock();
@@ -663,7 +667,7 @@ log_init_debug(char *f)
     dbg_rf = NULL;
   else if (!*f)
     dbg_rf = &rf_stderr;
-  else if (!(dbg_rf = rf_open(&root_pool, f, RF_APPEND)))
+  else if (!(dbg_rf = rf_open(&root_pool, f, RF_APPEND, 0)))
   {
     /* Cannot use die() nor log() here, logging is not yet initialized */
     fprintf(stderr, "bird: Unable to open debug file %s: %s\n", f, strerror(errno));
diff --git a/sysdep/unix/unix.h b/sysdep/unix/unix.h
index e73778ec..f193a8db 100644
--- a/sysdep/unix/unix.h
+++ b/sysdep/unix/unix.h
@@ -119,10 +119,10 @@ enum rf_mode {
   RF_APPEND,
 };
 
-struct rfile *rf_open(struct pool *, const char *name, enum rf_mode mode);
+struct rfile *rf_open(struct pool *, const char *name, enum rf_mode mode, off_t limit);
 off_t rf_size(struct rfile *);
 int rf_same(struct rfile *, struct rfile *);
-void rf_write(struct rfile *, const void *, size_t);
+int rf_write(struct rfile *, const void *, size_t);
 
 extern struct rfile rf_stderr;