Merge remote-tracking branch 'public/ticket6938'

Conflicts:
	src/tools/tor-resolve.c

12 files changed, 205 insertions, 79 deletions

diff --git a/changes/ticket6938 b/changes/ticket6938
new file mode 100644
index 0000000000..4e3979a7e9
--- /dev/null
+++ b/changes/ticket6938
@@ -0,0 +1,4 @@
+  o Minor features:
+
+    - When opening a log file at startup, send it every log message that we
+      generated between startup and opening it.  Closes ticket 6938.
diff --git a/src/common/log.c b/src/common/log.c
index 2e51e5c578..4b3817780b 100644
--- a/src/common/log.c
+++ b/src/common/log.c
@@ -117,15 +117,33 @@ static int syslog_count = 0;
 
 /** Represents a log message that we are going to send to callback-driven
  * loggers once we can do so in a non-reentrant way. */
-typedef struct pending_cb_message_t {
+typedef struct pending_log_message_t {
   int severity; /**< The severity of the message */
   log_domain_mask_t domain; /**< The domain of the message */
+  char *fullmsg; /**< The message, with all decorations */
   char *msg; /**< The content of the message */
-} pending_cb_message_t;
+} pending_log_message_t;
 
 /** Log messages waiting to be replayed onto callback-based logs */
 static smartlist_t *pending_cb_messages = NULL;
 
+/** Log messages waiting to be replayed once the logging system is initialized.
+ */
+static smartlist_t *pending_startup_messages = NULL;
+
+/** Number of bytes of messages queued in pending_startup_messages.  (This is
+ * the length of the messages, not the number of bytes used to store
+ * them.) */
+static size_t pending_startup_messages_len;
+
+/** True iff we should store messages while waiting for the logs to get
+ * configured. */
+static int queue_startup_messages = 1;
+
+/** Don't store more than this many bytes of messages while waiting for the
+ * logs to get configured. */
+#define MAX_STARTUP_MSG_LEN (1<<16)
+
 /** Lock the log_mutex to prevent others from changing the logfile_t list */
 #define LOCK_LOGS() STMT_BEGIN                                          \
   tor_mutex_acquire(&log_mutex);                                        \
@@ -329,6 +347,102 @@ format_msg(char *buf, size_t buf_len,
   return end_of_prefix;
 }
 
+/* Create a new pending_log_message_t with appropriate values */
+static pending_log_message_t *
+pending_log_message_new(int severity, log_domain_mask_t domain,
+                        const char *fullmsg, const char *shortmsg)
+{
+  pending_log_message_t *m = tor_malloc(sizeof(pending_log_message_t));
+  m->severity = severity;
+  m->domain = domain;
+  m->fullmsg = fullmsg ? tor_strdup(fullmsg) : NULL;
+  m->msg = tor_strdup(shortmsg);
+  return m;
+}
+
+/** Release all storage held by <b>msg</b>. */
+static void
+pending_log_message_free(pending_log_message_t *msg)
+{
+  if (!msg)
+    return;
+  tor_free(msg->msg);
+  tor_free(msg->fullmsg);
+  tor_free(msg);
+}
+
+/** Return true iff <b>lf</b> would like to receive a message with the specified
+ * <b>severity</b> in the specified <b>domain</b>.
+ */
+static INLINE int
+logfile_wants_message(const logfile_t *lf, int severity,
+                      log_domain_mask_t domain)
+{
+  if (! (lf->severities->masks[SEVERITY_MASK_IDX(severity)] & domain)) {
+    return 0;
+  }
+  if (! (lf->fd >= 0 || lf->is_syslog || lf->callback)) {
+    return 0;
+  }
+  if (lf->seems_dead) {
+    return 0;
+  }
+
+  return 1;
+}
+
+/** Send a message to <b>lf</b>.  The full message, with time prefix and
+ * severity, is in <b>buf</b>.  The message itself is in
+ * <b>msg_after_prefix</b>.  If <b>callbacks_deferred</b> points to true, then
+ * we already deferred this message for pending callbacks and don't need to do
+ * it again.  Otherwise, if we need to do it, do it, and set
+ * <b>callbacks_deferred</b> to 1. */
+static INLINE void
+logfile_deliver(logfile_t *lf, const char *buf, size_t msg_len,
+                const char *msg_after_prefix, log_domain_mask_t domain,
+                int severity, int *callbacks_deferred)
+{
+
+  if (lf->is_syslog) {
+#ifdef HAVE_SYSLOG_H
+#ifdef MAXLINE
+    /* Some syslog implementations have limits on the length of what you can
+     * pass them, and some very old ones do not detect overflow so well.
+     * Regrettably, they call their maximum line length MAXLINE. */
+#if MAXLINE < 64
+#warn "MAXLINE is a very low number; it might not be from syslog.h after all"
+#endif
+    char *m = msg_after_prefix;
+    if (msg_len >= MAXLINE)
+      m = tor_strndup(msg_after_prefix, MAXLINE-1);
+    syslog(severity, "%s", m);
+    if (m != msg_after_prefix) {
+      tor_free(m);
+    }
+#else
+    /* We have syslog but not MAXLINE.  That's promising! */
+    syslog(severity, "%s", msg_after_prefix);
+#endif
+#endif
+  } else if (lf->callback) {
+    if (domain & LD_NOCB) {
+      if (!*callbacks_deferred && pending_cb_messages) {
+        smartlist_add(pending_cb_messages,
+            pending_log_message_new(severity,domain,NULL,msg_after_prefix));
+        *callbacks_deferred = 1;
+      }
+    } else {
+      lf->callback(severity, domain, msg_after_prefix);
+    }
+  } else {
+    if (write_all(lf->fd, buf, msg_len, 0) < 0) { /* error */
+      /* don't log the error! mark this log entry to be blown away, and
+       * continue. */
+      lf->seems_dead = 1;
+    }
+  }
+}
+
 /** Helper: sends a message to the appropriate logfiles, at loglevel
  * <b>severity</b>.  If provided, <b>funcname</b> is prepended to the
  * message.  The actual message is derived as from tor_snprintf(format,ap).
@@ -354,20 +468,21 @@ logv,(int severity, log_domain_mask_t domain, const char *funcname,
   if ((! (domain & LD_NOCB)) && smartlist_len(pending_cb_messages))
     flush_pending_log_callbacks();
 
-  lf = logfiles;
-  while (lf) {
-    if (! (lf->severities->masks[SEVERITY_MASK_IDX(severity)] & domain)) {
-      lf = lf->next;
-      continue;
-    }
-    if (! (lf->fd >= 0 || lf->is_syslog || lf->callback)) {
-      lf = lf->next;
-      continue;
-    }
-    if (lf->seems_dead) {
-      lf = lf->next;
+  if (queue_startup_messages &&
+      pending_startup_messages_len < MAX_STARTUP_MSG_LEN) {
+    end_of_prefix =
+      format_msg(buf, sizeof(buf), domain, severity, funcname, suffix,
+      format, ap, &msg_len);
+    formatted = 1;
+
+    smartlist_add(pending_startup_messages,
+      pending_log_message_new(severity,domain,buf,end_of_prefix));
+    pending_startup_messages_len += msg_len;
+  }
+
+  for (lf = logfiles; lf; lf = lf->next) {
+    if (! logfile_wants_message(lf, severity, domain))
       continue;
-    }
 
     if (!formatted) {
       end_of_prefix =
@@ -376,51 +491,8 @@ logv,(int severity, log_domain_mask_t domain, const char *funcname,
       formatted = 1;
     }
 
-    if (lf->is_syslog) {
-#ifdef HAVE_SYSLOG_H
-      char *m = end_of_prefix;
-#ifdef MAXLINE
-      /* Some syslog implementations have limits on the length of what you can
-       * pass them, and some very old ones do not detect overflow so well.
-       * Regrettably, they call their maximum line length MAXLINE. */
-#if MAXLINE < 64
-#warn "MAXLINE is a very low number; it might not be from syslog.h after all"
-#endif
-      if (msg_len >= MAXLINE)
-        m = tor_strndup(end_of_prefix, MAXLINE-1);
-#endif
-      syslog(severity, "%s", m);
-#ifdef MAXLINE
-      if (m != end_of_prefix) {
-        tor_free(m);
-      }
-#endif
-#endif
-      lf = lf->next;
-      continue;
-    } else if (lf->callback) {
-      if (domain & LD_NOCB) {
-        if (!callbacks_deferred && pending_cb_messages) {
-          pending_cb_message_t *msg = tor_malloc(sizeof(pending_cb_message_t));
-          msg->severity = severity;
-          msg->domain = domain;
-          msg->msg = tor_strdup(end_of_prefix);
-          smartlist_add(pending_cb_messages, msg);
-
-          callbacks_deferred = 1;
-        }
-      } else {
-        lf->callback(severity, domain, end_of_prefix);
-      }
-      lf = lf->next;
-      continue;
-    }
-    if (write_all(lf->fd, buf, msg_len, 0) < 0) { /* error */
-      /* don't log the error! mark this log entry to be blown away, and
-       * continue. */
-      lf->seems_dead = 1;
-    }
-    lf = lf->next;
+    logfile_deliver(lf, buf, msg_len, end_of_prefix, domain, severity,
+      &callbacks_deferred);
   }
   UNLOCK_LOGS();
 }
@@ -724,12 +796,14 @@ void
 logs_free_all(void)
 {
   logfile_t *victim, *next;
-  smartlist_t *messages;
+  smartlist_t *messages, *messages2;
   LOCK_LOGS();
   next = logfiles;
   logfiles = NULL;
   messages = pending_cb_messages;
   pending_cb_messages = NULL;
+  messages2 = pending_startup_messages;
+  pending_startup_messages = NULL;
   UNLOCK_LOGS();
   while (next) {
     victim = next;
@@ -739,12 +813,18 @@ logs_free_all(void)
   }
   tor_free(appname);
 
-  SMARTLIST_FOREACH(messages, pending_cb_message_t *, msg, {
-      tor_free(msg->msg);
-      tor_free(msg);
+  SMARTLIST_FOREACH(messages, pending_log_message_t *, msg, {
+      pending_log_message_free(msg);
     });
   smartlist_free(messages);
 
+  if (messages2) {
+    SMARTLIST_FOREACH(messages2, pending_log_message_t *, msg, {
+        pending_log_message_free(msg);
+      });
+    smartlist_free(messages2);
+  }
+
   /* We _could_ destroy the log mutex here, but that would screw up any logs
    * that happened between here and the end of execution. */
 }
@@ -839,7 +919,7 @@ add_stream_log(const log_severity_list_t *severity, const char *name, int fd)
 
 /** Initialize the global logging facility */
 void
-init_logging(void)
+init_logging(int disable_startup_queue)
 {
   if (!log_mutex_initialized) {
     tor_mutex_init(&log_mutex);
@@ -847,6 +927,11 @@ init_logging(void)
   }
   if (pending_cb_messages == NULL)
     pending_cb_messages = smartlist_new();
+  if (disable_startup_queue)
+    queue_startup_messages = 0;
+  if (pending_startup_messages == NULL && queue_startup_messages) {
+    pending_startup_messages = smartlist_new();
+  }
 }
 
 /** Set whether we report logging domains as a part of our log messages.
@@ -932,7 +1017,7 @@ flush_pending_log_callbacks(void)
   messages = pending_cb_messages;
   pending_cb_messages = smartlist_new();
   do {
-    SMARTLIST_FOREACH_BEGIN(messages, pending_cb_message_t *, msg) {
+    SMARTLIST_FOREACH_BEGIN(messages, pending_log_message_t *, msg) {
       const int severity = msg->severity;
       const int domain = msg->domain;
       for (lf = logfiles; lf; lf = lf->next) {
@@ -942,8 +1027,7 @@ flush_pending_log_callbacks(void)
         }
         lf->callback(severity, domain, msg->msg);
       }
-      tor_free(msg->msg);
-      tor_free(msg);
+      pending_log_message_free(msg);
     } SMARTLIST_FOREACH_END(msg);
     smartlist_clear(messages);
 
@@ -957,6 +1041,39 @@ flush_pending_log_callbacks(void)
   UNLOCK_LOGS();
 }
 
+/** Flush all the messages we stored from startup while waiting for log
+ * initialization.
+ */
+void
+flush_log_messages_from_startup(void)
+{
+  logfile_t *lf;
+
+  LOCK_LOGS();
+  queue_startup_messages = 0;
+  pending_startup_messages_len = 0;
+  if (! pending_startup_messages)
+    goto out;
+
+  SMARTLIST_FOREACH_BEGIN(pending_startup_messages, pending_log_message_t *,
+                          msg) {
+    int callbacks_deferred = 0;
+    for (lf = logfiles; lf; lf = lf->next) {
+      if (! logfile_wants_message(lf, msg->severity, msg->domain))
+        continue;
+
+      logfile_deliver(lf, msg->fullmsg, strlen(msg->fullmsg), msg->msg,
+                      msg->domain, msg->severity, &callbacks_deferred);
+    }
+    pending_log_message_free(msg);
+  } SMARTLIST_FOREACH_END(msg);
+  smartlist_free(pending_startup_messages);
+  pending_startup_messages = NULL;
+
+ out:
+  UNLOCK_LOGS();
+}
+
 /** Close any log handlers added by add_temp_log() or marked by
  * mark_logs_temp(). */
 void
diff --git a/src/common/torlog.h b/src/common/torlog.h
index 34e39b4b94..8105af4351 100644
--- a/src/common/torlog.h
+++ b/src/common/torlog.h
@@ -121,7 +121,7 @@ typedef struct log_severity_list_t {
 /** Callback type used for add_callback_log. */
 typedef void (*log_callback)(int severity, uint32_t domain, const char *msg);
 
-void init_logging(void);
+void init_logging(int disable_startup_queue);
 int parse_log_level(const char *level);
 const char *log_level_to_string(int level);
 int parse_log_severity_config(const char **cfg,
@@ -147,6 +147,7 @@ void mark_logs_temp(void);
 void change_callback_log_severity(int loglevelMin, int loglevelMax,
                                   log_callback cb);
 void flush_pending_log_callbacks(void);
+void flush_log_messages_from_startup(void);
 void log_set_application_name(const char *name);
 void set_log_time_granularity(int granularity_msec);
 void truncate_logs(void);
diff --git a/src/or/config.c b/src/or/config.c
index 5555a2eb3b..2318e63b8e 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -1001,7 +1001,7 @@ options_act_reversible(const or_options_t *old_options, char **msg)
   int running_tor = options->command == CMD_RUN_TOR;
   int set_conn_limit = 0;
   int r = -1;
-  int logs_marked = 0;
+  int logs_marked = 0, logs_initialized = 0;
   int old_min_log_level = get_min_log_level();
 
   /* Daemonize _first_, since we only want to open most of this stuff in
@@ -1131,6 +1131,7 @@ options_act_reversible(const or_options_t *old_options, char **msg)
     *msg = tor_strdup("Failed to init Log options. See logs for details.");
     goto rollback;
   }
+  logs_initialized = 1;
 
  commit:
   r = 0;
@@ -1143,6 +1144,9 @@ options_act_reversible(const or_options_t *old_options, char **msg)
     tor_free(severity);
     tor_log_update_sigsafe_err_fds();
   }
+  if (logs_initialized) {
+    flush_log_messages_from_startup();
+  }
 
   {
     const char *badness = NULL;
diff --git a/src/or/main.c b/src/or/main.c
index 61efc1f6f2..1d26223eb6 100644
--- a/src/or/main.c
+++ b/src/or/main.c
@@ -2955,7 +2955,7 @@ tor_main(int argc, char *argv[])
 
   update_approx_time(time(NULL));
   tor_threads_init();
-  init_logging();
+  init_logging(0);
 #ifdef USE_DMALLOC
   {
     /* Instruct OpenSSL to use our internal wrappers for malloc,
diff --git a/src/test/bench.c b/src/test/bench.c
index 1204854b36..825299835b 100644
--- a/src/test/bench.c
+++ b/src/test/bench.c
@@ -631,7 +631,7 @@ main(int argc, const char **argv)
   crypto_seed_rng(1);
   crypto_init_siphash_key();
   options = options_new();
-  init_logging();
+  init_logging(1);
   options->command = CMD_RUN_UNITTESTS;
   options->DataDirectory = tor_strdup("");
   options_init(options);
diff --git a/src/test/test.c b/src/test/test.c
index d2813ed42a..16ad6f3ae6 100644
--- a/src/test/test.c
+++ b/src/test/test.c
@@ -1366,7 +1366,7 @@ main(int c, const char **v)
   update_approx_time(time(NULL));
   options = options_new();
   tor_threads_init();
-  init_logging();
+  init_logging(1);
   configure_backtrace_handler(get_version());
 
   for (i_out = i = 1; i < c; ++i) {
diff --git a/src/test/test_bt_cl.c b/src/test/test_bt_cl.c
index 720ccd4627..d7a3cab7c3 100644
--- a/src/test/test_bt_cl.c
+++ b/src/test/test_bt_cl.c
@@ -96,7 +96,7 @@ main(int argc, char **argv)
     return 1;
   }
 
-  init_logging();
+  init_logging(1);
   set_log_severity_config(LOG_WARN, LOG_ERR, &severity);
   add_stream_log(&severity, "stdout", STDOUT_FILENO);
   tor_log_update_sigsafe_err_fds();
diff --git a/src/test/test_logging.c b/src/test/test_logging.c
index 9f57000bea..76cc9e970e 100644
--- a/src/test/test_logging.c
+++ b/src/test/test_logging.c
@@ -19,7 +19,7 @@ test_get_sigsafe_err_fds(void *arg)
   int n;
   log_severity_list_t include_bug, no_bug, no_bug2;
   (void) arg;
-  init_logging();
+  init_logging(1);
 
   n = tor_log_get_sigsafe_err_fds(&fds);
   tt_int_op(n, ==, 1);
@@ -87,7 +87,7 @@ test_sigsafe_err(void *arg)
 
   set_log_severity_config(LOG_WARN, LOG_ERR, &include_bug);
 
-  init_logging();
+  init_logging(1);
   mark_logs_temp();
   add_file_log(&include_bug, fn, 0);
   tor_log_update_sigsafe_err_fds();
diff --git a/src/tools/tor-checkkey.c b/src/tools/tor-checkkey.c
index d50f12ed2a..295da33051 100644
--- a/src/tools/tor-checkkey.c
+++ b/src/tools/tor-checkkey.c
@@ -21,7 +21,7 @@ main(int c, char **v)
   int wantdigest=0;
   int fname_idx;
   char *fname=NULL;
-  init_logging();
+  init_logging(1);
 
   if (c < 2) {
     fprintf(stderr, "Hi. I'm tor-checkkey.  Tell me a filename that "
diff --git a/src/tools/tor-gencert.c b/src/tools/tor-gencert.c
index fae26ef956..0fe6821ff8 100644
--- a/src/tools/tor-gencert.c
+++ b/src/tools/tor-gencert.c
@@ -525,7 +525,7 @@ int
 main(int argc, char **argv)
 {
   int r = 1;
-  init_logging();
+  init_logging(1);
 
   /* Don't bother using acceleration. */
   if (crypto_global_init(0, NULL, NULL)) {
diff --git a/src/tools/tor-resolve.c b/src/tools/tor-resolve.c
index 480c7e52ca..74af511acb 100644
--- a/src/tools/tor-resolve.c
+++ b/src/tools/tor-resolve.c
@@ -344,7 +344,7 @@ main(int argc, char **argv)
   char *result_hostname = NULL;
   log_severity_list_t *s = tor_malloc_zero(sizeof(log_severity_list_t));
 
-  init_logging();
+  init_logging(1);
   sandbox_disable_getaddrinfo_cache();
 
   arg = &argv[1];