nghttpx: better handle /dev/stderr and /dev/stdout

src/shrpx_log.cc

@@ -326,31 +326,25 @@ void upstream_accesslog(const std::vector<LogFragment> &lfv,
 
 int reopen_log_files() {
   int res = 0;
+  int new_accesslog_fd = -1;
+  int new_errorlog_fd = -1;
 
   auto lgconf = log_config();
 
-  if (lgconf->accesslog_fd != -1) {
-    close(lgconf->accesslog_fd);
-    lgconf->accesslog_fd = -1;
-  }
-
   if (!get_config()->accesslog_syslog && get_config()->accesslog_file) {
 
-    lgconf->accesslog_fd =
-        util::reopen_log_file(get_config()->accesslog_file.get());
+    new_accesslog_fd = util::open_log_file(get_config()->accesslog_file.get());
 
-    if (lgconf->accesslog_fd == -1) {
+    if (new_accesslog_fd == -1) {
       LOG(ERROR) << "Failed to open accesslog file "
                  << get_config()->accesslog_file.get();
       res = -1;
     }
   }
 
-  int new_errorlog_fd = -1;
-
   if (!get_config()->errorlog_syslog && get_config()->errorlog_file) {
 
-    new_errorlog_fd = util::reopen_log_file(get_config()->errorlog_file.get());
+    new_errorlog_fd = util::open_log_file(get_config()->errorlog_file.get());
 
     if (new_errorlog_fd == -1) {
       if (lgconf->errorlog_fd != -1) {
@@ -365,16 +359,13 @@ int reopen_log_files() {
     }
   }
 
-  if (lgconf->errorlog_fd != -1) {
-    close(lgconf->errorlog_fd);
-    lgconf->errorlog_fd = -1;
-    lgconf->errorlog_tty = false;
-  }
+  util::close_log_file(lgconf->accesslog_fd);
+  util::close_log_file(lgconf->errorlog_fd);
 
-  if (new_errorlog_fd != -1) {
-    lgconf->errorlog_fd = new_errorlog_fd;
-    lgconf->errorlog_tty = isatty(lgconf->errorlog_fd);
-  }
+  lgconf->accesslog_fd = new_accesslog_fd;
+  lgconf->errorlog_fd = new_errorlog_fd;
+  lgconf->errorlog_tty = (new_errorlog_fd == -1) ?
+    false : isatty(new_errorlog_fd);
 
   return res;
 }

src/util.cc

@@ -657,7 +657,21 @@ std::string numeric_name(const struct sockaddr *sa, socklen_t salen) {
   return host.data();
 }
 
-int reopen_log_file(const char *path) {
+
+void close_log_file(int &fd) {
+  if (fd != STDERR_FILENO && fd != STDOUT_FILENO && fd != -1) {
+    close(fd);
+  }
+  fd = -1;
+}
+
+int open_log_file(const char *path) {
+  if (strcmp(path, "/dev/stdout") == 0) {
+    return STDOUT_FILENO;
+  }
+  if (strcmp(path, "/dev/stderr") == 0) {
+    return STDERR_FILENO;
+  }
 #if defined(__ANDROID__) || defined(ANDROID)
   int fd;
 

src/util.h

@@ -516,10 +516,15 @@ bool numeric_host(const char *hostname);
 // failed, "unknown" is returned.
 std::string numeric_name(const struct sockaddr *sa, socklen_t salen);
 
+// Closes |fd| which was returned by open_log_file (see below)
+// and sets it to -1. In the case that |fd| points to stdout or
+// stderr, or is -1, the descriptor is not closed (but still set to -1).
+void close_log_file(int &fd);
+
 // Opens |path| with O_APPEND enabled.  If file does not exist, it is
 // created first.  This function returns file descriptor referring the
 // opened file if it succeeds, or -1.
-int reopen_log_file(const char *path);
+int open_log_file(const char *path);
 
 // Returns ASCII dump of |data| of length |len|.  Only ASCII printable
 // characters are preserved.  Other characters are replaced with ".".