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[tor-commits] [tor/maint-0.4.1] log: Close log and err file descriptors before aborting
commit 1609916c79612b5cc3a9b363a22f1a9035f2f77b
Author: teor <teor@xxxxxxxxxxxxxx>
Date: Wed Sep 4 17:16:49 2019 +1000
log: Close log and err file descriptors before aborting
Part of 31594.
---
src/lib/err/backtrace.c | 2 +-
src/lib/err/torerr.c | 16 ++++++++++++++--
src/lib/err/torerr.h | 6 ++++--
src/lib/log/log.c | 42 ++++++++++++++++++++++++++++++++++++++++--
src/lib/log/log.h | 1 +
src/lib/log/util_bug.c | 11 +++++++----
src/trunnel/trunnel-local.h | 1 +
7 files changed, 68 insertions(+), 11 deletions(-)
diff --git a/src/lib/err/backtrace.c b/src/lib/err/backtrace.c
index 1d1b3bcfa..643fe862b 100644
--- a/src/lib/err/backtrace.c
+++ b/src/lib/err/backtrace.c
@@ -172,7 +172,7 @@ crash_handler(int sig, siginfo_t *si, void *ctx_)
for (i=0; i < n_fds; ++i)
backtrace_symbols_fd(cb_buf, (int)depth, fds[i]);
- abort();
+ tor_raw_abort_();
}
/** Write a backtrace to all of the emergency-error fds. */
diff --git a/src/lib/err/torerr.c b/src/lib/err/torerr.c
index f460fd837..21b28a5f6 100644
--- a/src/lib/err/torerr.c
+++ b/src/lib/err/torerr.c
@@ -208,6 +208,18 @@ tor_raw_assertion_failed_msg_(const char *file, int line, const char *expr,
dump_stack_symbols_to_error_fds();
}
+/**
+ * Call the abort() function to kill the current process with a fatal
+ * error. But first, close the raw error file descriptors, so error messages
+ * are written before process termination.
+ **/
+void
+tor_raw_abort_(void)
+{
+ tor_log_close_sigsafe_err_fds();
+ abort();
+}
+
/* As format_{hex,dex}_number_sigsafe, but takes a <b>radix</b> argument
* in range 2..16 inclusive. */
static int
@@ -242,7 +254,7 @@ format_number_sigsafe(unsigned long x, char *buf, int buf_len,
unsigned digit = (unsigned) (x % radix);
if (cp <= buf) {
/* Not tor_assert(); see above. */
- abort();
+ tor_raw_abort_();
}
--cp;
*cp = "0123456789ABCDEF"[digit];
@@ -251,7 +263,7 @@ format_number_sigsafe(unsigned long x, char *buf, int buf_len,
/* NOT tor_assert; see above. */
if (cp != buf) {
- abort(); // LCOV_EXCL_LINE
+ tor_raw_abort_(); // LCOV_EXCL_LINE
}
return len;
diff --git a/src/lib/err/torerr.h b/src/lib/err/torerr.h
index 3b86d2039..a41109527 100644
--- a/src/lib/err/torerr.h
+++ b/src/lib/err/torerr.h
@@ -20,13 +20,13 @@
#define raw_assert(expr) STMT_BEGIN \
if (!(expr)) { \
tor_raw_assertion_failed_msg_(__FILE__, __LINE__, #expr, NULL); \
- abort(); \
+ tor_raw_abort_(); \
} \
STMT_END
#define raw_assert_unreached(expr) raw_assert(0)
#define raw_assert_unreached_msg(msg) STMT_BEGIN \
tor_raw_assertion_failed_msg_(__FILE__, __LINE__, "0", (msg)); \
- abort(); \
+ tor_raw_abort_(); \
STMT_END
void tor_raw_assertion_failed_msg_(const char *file, int line,
@@ -43,6 +43,8 @@ void tor_log_reset_sigsafe_err_fds(void);
void tor_log_close_sigsafe_err_fds(void);
void tor_log_sigsafe_err_set_granularity(int ms);
+void tor_raw_abort_(void) ATTR_NORETURN;
+
int format_hex_number_sigsafe(unsigned long x, char *buf, int max_len);
int format_dec_number_sigsafe(unsigned long x, char *buf, int max_len);
diff --git a/src/lib/log/log.c b/src/lib/log/log.c
index 2214d4b59..4adcc5cf5 100644
--- a/src/lib/log/log.c
+++ b/src/lib/log/log.c
@@ -224,6 +224,7 @@ int log_global_min_severity_ = LOG_NOTICE;
static void delete_log(logfile_t *victim);
static void close_log(logfile_t *victim);
+static void close_log_sigsafe(logfile_t *victim);
static char *domain_to_string(log_domain_mask_t domain,
char *buf, size_t buflen);
@@ -833,6 +834,30 @@ logs_free_all(void)
* that happened between here and the end of execution. */
}
+/** Close signal-safe log files.
+ * Closing the log files makes the process and OS flush log buffers.
+ *
+ * This function is safe to call from a signal handler. It should only be
+ * called when shutting down the log or err modules. It is currenly called
+ * by the err module, when terminating the process on an abnormal condition.
+ */
+void
+logs_close_sigsafe(void)
+{
+ logfile_t *victim, *next;
+ /* We can't LOCK_LOGS() in a signal handler, because it may call
+ * signal-unsafe functions. And we can't deallocate memory, either. */
+ next = logfiles;
+ logfiles = NULL;
+ while (next) {
+ victim = next;
+ next = next->next;
+ if (victim->needs_close) {
+ close_log_sigsafe(victim);
+ }
+ }
+}
+
/** Remove and free the log entry <b>victim</b> from the linked-list
* logfiles (it is probably present, but it might not be due to thread
* racing issues). After this function is called, the caller shouldn't
@@ -859,13 +884,26 @@ delete_log(logfile_t *victim)
}
/** Helper: release system resources (but not memory) held by a single
- * logfile_t. */
+ * signal-safe logfile_t. If the log's resources can not be released in
+ * a signal handler, does nothing. */
static void
-close_log(logfile_t *victim)
+close_log_sigsafe(logfile_t *victim)
{
if (victim->needs_close && victim->fd >= 0) {
+ /* We can't do anything useful here if close() fails: we're shutting
+ * down logging, and the err module only does fatal errors. */
close(victim->fd);
victim->fd = -1;
+ }
+}
+
+/** Helper: release system resources (but not memory) held by a single
+ * logfile_t. */
+static void
+close_log(logfile_t *victim)
+{
+ if (victim->needs_close) {
+ close_log_sigsafe(victim);
} else if (victim->is_syslog) {
#ifdef HAVE_SYSLOG_H
if (--syslog_count == 0) {
diff --git a/src/lib/log/log.h b/src/lib/log/log.h
index dbc1c4702..360951783 100644
--- a/src/lib/log/log.h
+++ b/src/lib/log/log.h
@@ -170,6 +170,7 @@ void logs_set_domain_logging(int enabled);
int get_min_log_level(void);
void switch_logs_debug(void);
void logs_free_all(void);
+void logs_close_sigsafe(void);
void add_temp_log(int min_severity);
void close_temp_logs(void);
void rollback_log_changes(void);
diff --git a/src/lib/log/util_bug.c b/src/lib/log/util_bug.c
index c65a91ae9..343510884 100644
--- a/src/lib/log/util_bug.c
+++ b/src/lib/log/util_bug.c
@@ -11,6 +11,7 @@
#include "lib/log/util_bug.h"
#include "lib/log/log.h"
#include "lib/err/backtrace.h"
+#include "lib/err/torerr.h"
#ifdef TOR_UNIT_TESTS
#include "lib/smartlist_core/smartlist_core.h"
#include "lib/smartlist_core/smartlist_foreach.h"
@@ -122,16 +123,18 @@ tor_bug_occurred_(const char *fname, unsigned int line,
}
/**
- * Call the abort() function to kill the current process with a fatal
- * error.
+ * Call the tor_raw_abort_() function to close raw logs, then kill the current
+ * process with a fatal error. But first, close the file-based log file
+ * descriptors, so error messages are written before process termination.
*
* (This is a separate function so that we declare it in util_bug.h without
- * including stdlib in all the users of util_bug.h)
+ * including torerr.h in all the users of util_bug.h)
**/
void
tor_abort_(void)
{
- abort();
+ logs_close_sigsafe();
+ tor_raw_abort_();
}
#ifdef _WIN32
diff --git a/src/trunnel/trunnel-local.h b/src/trunnel/trunnel-local.h
index c4118fce4..80da37156 100644
--- a/src/trunnel/trunnel-local.h
+++ b/src/trunnel/trunnel-local.h
@@ -14,5 +14,6 @@
#define trunnel_reallocarray tor_reallocarray
#define trunnel_assert tor_assert
#define trunnel_memwipe(mem, len) memwipe((mem), 0, (len))
+#define trunnel_abort tor_abort_
#endif
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