nghttpx: Handle return value of write(2)

src/shrpx_exec.cc

@@ -85,7 +85,8 @@ int exec_read_command(Process &proc, char *const argv[]) {
     rv = shrpx_signal_unblock_all();
     if (rv != 0) {
       constexpr char msg[] = "Unblocking all signals failed\n";
-      write(STDERR_FILENO, msg, str_size(msg));
+      while (write(STDERR_FILENO, msg, str_size(msg)) == -1 && errno == EINTR)
+        ;
       nghttp2_Exit(EXIT_FAILURE);
     }
 
@@ -95,7 +96,8 @@ int exec_read_command(Process &proc, char *const argv[]) {
     rv = execv(argv[0], argv);
     if (rv == -1) {
       constexpr char msg[] = "Could not execute command\n";
-      write(STDERR_FILENO, msg, str_size(msg));
+      while (write(STDERR_FILENO, msg, str_size(msg)) == -1 && errno == EINTR)
+        ;
       nghttp2_Exit(EXIT_FAILURE);
     }
     // unreachable