decouple use_syslog from pid_flags

Sometimes we need processes to run in the foreground to be supervised
and at the same time use syslog facility instead of logging its stdout,
stderr output

src/jconf.c

@@ -313,6 +313,12 @@ read_jconf(const char *file)
                 check_json_value_type(value, json_boolean,
                     "invalid config file: option 'ipv6_first' must be a boolean");
                 conf.ipv6_first = value->u.boolean;
+#ifdef HAS_SYSLOG
+            } else if (strcmp(name, "use_syslog") == 0) {
+                check_json_value_type(value, json_boolean,
+                    "invalid config file: option 'use_syslog' must be a boolean");
+                use_syslog = value->u.boolean;
+#endif
             }
         }
     } else {

src/local.c

@@ -1522,8 +1522,8 @@ main(int argc, char **argv)
         local_addr = "127.0.0.1";
     }
 
+    USE_SYSLOG(argv[0], pid_flags);
     if (pid_flags) {
-        USE_SYSLOG(argv[0]);
         daemonize(pid_path);
     }
 

src/manager.c

@@ -1149,8 +1149,8 @@ main(int argc, char **argv)
         timeout = "60";
     }
 
+    USE_SYSLOG(argv[0], pid_flags);
     if (pid_flags) {
-        USE_SYSLOG(argv[0]);
         daemonize(pid_path);
     }
 

src/redir.c

@@ -1140,8 +1140,8 @@ main(int argc, char **argv)
 #endif
     }
 
+    USE_SYSLOG(argv[0], pid_flags);
     if (pid_flags) {
-        USE_SYSLOG(argv[0]);
         daemonize(pid_path);
     }
 

src/server.c

@@ -1726,8 +1726,8 @@ main(int argc, char **argv)
     }
 #endif
 
+    USE_SYSLOG(argv[0], pid_flags);
     if (pid_flags) {
-        USE_SYSLOG(argv[0]);
         daemonize(pid_path);
     }
 

src/tunnel.c

@@ -1022,8 +1022,8 @@ main(int argc, char **argv)
         local_addr = "127.0.0.1";
     }
 
+    USE_SYSLOG(argv[0], pid_flags);
     if (pid_flags) {
-        USE_SYSLOG(argv[0]);
         daemonize(pid_path);
     }
 

src/utils.h

@@ -35,7 +35,7 @@
 
 #include <android/log.h>
 #define USE_TTY()
-#define USE_SYSLOG(ident)
+#define USE_SYSLOG(ident, _cond)
 #define LOGI(...)                                                \
     ((void)__android_log_print(ANDROID_LOG_DEBUG, "shadowsocks", \
                                __VA_ARGS__))
@@ -53,7 +53,7 @@
 extern FILE *logfile;
 #define TIME_FORMAT "%Y-%m-%d %H:%M:%S"
 #define USE_TTY()
-#define USE_SYSLOG(ident)
+#define USE_SYSLOG(ident, _cond)
 #define USE_LOGFILE(ident)                                     \
     do {                                                       \
         if (ident != NULL) { logfile = fopen(ident, "w+"); } } \
@@ -99,11 +99,15 @@ extern int use_syslog;
         use_tty = isatty(STDERR_FILENO); \
     } while (0)
 
-#define USE_SYSLOG(ident)                          \
-    do {                                           \
-        use_syslog = 1;                            \
-        openlog((ident), LOG_CONS | LOG_PID, 0); } \
-    while (0)
+#define USE_SYSLOG(_ident, _cond)                       \
+    do {                                                \
+        if (!use_syslog && (_cond)) {                   \
+            use_syslog = 1;                             \
+        }                                               \
+        if (use_syslog) {                               \
+            openlog((_ident), LOG_CONS | LOG_PID, 0);   \
+        }                                               \
+    } while (0)
 
 #define LOGI(format, ...)                                                        \
     do {                                                                         \