nginx-util: add package

This can do the main work of nginx/nginx-ssl init script.
For nginx-ssl it can create selfsigned certificates, too.
It uses libpcre and libopenssl iff nginx(-ssl) uses them.

Signed-off-by: Peter Stadler <peter.stadler@student.uibk.ac.at>

net/nginx-util/src/nginx-util.hpp

@@ -0,0 +1,120 @@
+#ifndef __NGINX_UTIL_H
+#define __NGINX_UTIL_H
+
+#include <array>
+#include <cerrno>
+#include <cstdio>
+#include <cstring>
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <string_view>
+#include <unistd.h>
+
+#ifndef NO_UBUS
+#include "ubus-cxx.hpp"
+#endif
+
+
+static constexpr auto NGINX_UTIL = std::string_view{"/usr/bin/nginx-util"};
+
+static constexpr auto NGINX_CONF = std::string_view{"/etc/nginx/nginx.conf"};
+
+static constexpr auto CONF_DIR = std::string_view{"/etc/nginx/conf.d/"};
+
+static constexpr auto LAN_NAME = std::string_view{"_lan"};
+
+static constexpr auto LAN_LISTEN =std::string_view{"/var/lib/nginx/lan.listen"};
+
+static constexpr auto LAN_LISTEN_DEFAULT =
+    std::string_view{"/var/lib/nginx/lan.listen.default"};
+
+
+// mode: optional ios::binary and/or ios::app (default ios::trunc)
+void write_file(const std::string_view & name, const std::string & str,
+                std::ios_base::openmode flag=std::ios::trunc);
+
+
+// mode: optional ios::binary (internally ios::ate|ios::in)
+auto read_file(const std::string_view & name,
+                      std::ios_base::openmode mode=std::ios::in) -> std::string;
+
+
+// all S must be convertible to const char[]
+template<typename ...S>
+auto call(const std::string & program, S... args) -> pid_t;
+
+
+void create_lan_listen();
+
+
+void init_lan();
+
+
+void get_env();
+
+
+
+// --------------------- partial implementation: ------------------------------
+
+
+void write_file(const std::string_view & name, const std::string & str,
+                const std::ios_base::openmode flag)
+{
+    std::ofstream file(name.data(), flag);
+    if (!file.good()) {
+        throw std::ofstream::failure(
+            "write_file error: cannot open " + std::string{name});
+    }
+
+    file<<str<<std::flush;
+
+    file.close();
+}
+
+
+auto read_file(const std::string_view & name,
+                      const std::ios_base::openmode mode) -> std::string
+{
+    std::ifstream file(name.data(), mode|std::ios::ate);
+    if (!file.good()) {
+        throw std::ifstream::failure(
+            "read_file error: cannot open " + std::string{name});
+    }
+
+    std::string ret{};
+    const size_t size = file.tellg();
+    ret.reserve(size);
+
+    file.seekg(0);
+    ret.assign((std::istreambuf_iterator<char>(file)),
+                std::istreambuf_iterator<char>());
+
+    file.close();
+    return ret;
+}
+
+
+template<typename ...S>
+auto call(const char * program, S... args) -> pid_t
+{
+    pid_t pid = fork();
+
+    if (pid==0) { //child:
+        std::array<char *, sizeof...(args)+2> argv =
+        { strdup(program), strdup(args)..., nullptr };
+
+        execv(program, argv.data()); // argv cannot be const char * const[]!
+
+        _exit(EXIT_FAILURE);  // exec never returns.
+    } else if (pid>0) { //parent:
+        return pid;
+    }
+
+    std::string errmsg = "call error: cannot fork (";
+    errmsg += std::to_string(errno) + "): " + std::strerror(errno);
+    throw std::runtime_error(errmsg.c_str());
+}
+
+
+#endif