Fix how %m behaves in the log format

[platform/core/system/dlog.git] / src / libdlog / log.c

diff --git a/src/libdlog/log.c b/src/libdlog/log.c
index 023990f..7119d49 100644 (file)
--- a/src/libdlog/log.c
+++ b/src/libdlog/log.c
@@ -111,7 +111,7 @@ _Thread_local int32_t cached_tid = 0;
 
 static inline int32_t get_cached_pid()
 {
-       return (cached_pid = cached_pid ?: getpid());
+       return cached_pid;
 }
 
 static inline int32_t get_cached_tid()
@@ -261,6 +261,8 @@ bool __configure(void)
        __attribute__((cleanup(log_config_free))) struct log_config static_config = {};
        __attribute__((cleanup(log_config_free))) struct log_config both_config = {};
 
+       cached_pid = getpid();
+
        if (log_config_read(&static_config) < 0)
                return false;
        log_config_copy(&both_config, &static_config);
@@ -461,31 +463,25 @@ static int dlog_check_limiter(log_id_t log_id, int prio, const char *tag)
        return DLOG_ERROR_NONE;
 }
 
-static int __write_to_log_critical_section(log_id_t log_id, int prio, const char *tag, const char *fmt, va_list ap, bool check_should_log)
+static int __write_to_log_critical_section(log_id_t log_id, int prio, const char *tag, size_t buf_size, char buf[static buf_size], int buf_len, bool check_should_log)
 {
        if ((check_should_log || limiter_apply_to_all_buffers) && (dlog_check_limiter(log_id, prio, tag) < 0))
                return DLOG_ERROR_NONE;
 
        log_id = get_log_id_from_sink(log_id);
 
-       char buf[LOG_MAX_PAYLOAD_SIZE];
-       int len = vsnprintf(buf, sizeof buf, fmt, ap);
-       if (len < 0)
-               return DLOG_ERROR_NONE;
-       else if (len >= sizeof buf)
-               len = sizeof buf - 1;
 
        // Temporary workaround, see temporary.c
-       prepend_container_tag_if_in_container(sizeof buf, buf, &len);
+       prepend_container_tag_if_in_container(buf_size, buf, &buf_len);
 
        struct timespec tp;
        int r;
        if (deduplicate_func && !clock_gettime(CLOCK_MONOTONIC, &tp)) {
-               dlog_deduplicate_e ret = deduplicate_func(buf, len, &tp);
+               dlog_deduplicate_e ret = deduplicate_func(buf, buf_len, &tp);
                if (ret == DLOG_DEDUPLICATE)
                        return DLOG_ERROR_NONE;
                else if (ret == DLOG_DO_NOT_DEDUPLICATE_BUT_WARN)
-                       deduplicate_warn(buf, sizeof buf, len);
+                       deduplicate_warn(buf, buf_size, buf_len);
                r = write_to_log(log_id, prio, tag, buf, &tp, get_cached_pid(), get_cached_tid());
        } else
                r = write_to_log(log_id, prio, tag, buf, NULL, get_cached_pid(), get_cached_tid());
@@ -498,6 +494,18 @@ static int __write_to_log_critical_section(log_id_t log_id, int prio, const char
 
 static int __write_to_log(log_id_t log_id, int prio, const char *tag, const char *fmt, va_list ap, bool check_should_log, bool secure_log)
 {
+       /* Write down the log first, before all other checks. This
+        * is because validity checks may involve syscalls, which
+        * could overwrite `errno` and ruin the `%m` specifier if
+        * the client specifies it in format. */
+       char buf[LOG_MAX_PAYLOAD_SIZE];
+       int len = vsnprintf(buf, sizeof buf, fmt, ap);
+       if (len < 0)
+               return DLOG_ERROR_NONE; // not really, but no better choice and not too realistic
+       else if (len >= sizeof buf)
+               len = sizeof buf - 1;
+
+
        int ret = dlog_check_validity(log_id, prio, tag, check_should_log);
        if (ret < 0)
                return ret;
@@ -526,7 +534,7 @@ static int __write_to_log(log_id_t log_id, int prio, const char *tag, const char
        else if (secure_log && !enable_secure_logs)
                ret = 0;
        else
-               ret = __write_to_log_critical_section(log_id, prio, tag, fmt, ap, check_should_log);
+               ret = __write_to_log_critical_section(log_id, prio, tag, sizeof buf, buf, len, check_should_log);
 
        if (should_disable_cancels)
                pthread_setcancelstate(old_cancel_state, NULL);