对“`PQconnectdb”的未定义引用

Question

最近，我正在处理一个项目，请求向其添加postgresql支持。项目是用C(它的开源Janus网关)编写的。

我按照下面的步骤安装后置和libps-dev。

sudo apt-get install postgresql
sudo apt-get install libpq-dev
$ sudo -u postgres psql postgres
psql (9.3.9)
Type "help" for help.

postgres=# \password postgres

然后在我的头(connect.h)文件中：

#include <postgresql/libpq-fe.h>
#include "debug.h"

/*! \brief Connect to postgresql database
 * If successfull, returns PGconn type
 * If not exits the program
 * @param[in] postgres connection params, ex. username, db, host, etc.
 */
PGconn *connect_to_database(gchar connection_params);

/*! \brief Closes connection to database
 * @param[in] PGconn instance
 */
PGconn *close_connection_to_database(PGconn *pgconn);

以及我的.c(connect.c)文件：

/*! \file    db.c
 * \author   ...
 * \copyright GNU General Public License v3
 * \brief    Event handler notifications (headers)
 * \details  This file contains methods for safely creating databse connection
 * to postgresql and then closing it.
 * 
 * \ingroup db
 * \ref db
 */

#include "./connect.h"

PGconn *connect_to_database(gchar connection_params) {
  JANUS_LOG(LOG_WARN, "TESTINGSSS \n\n\n\n");


  const char test_connect = "testings";

  PGconn *conn = PQconnectdb(test_connect);

  return conn;
}

在make上我得到：

todns@todnnns-VirtualBox ~/Projects/janus-gateway $ make
make  all-recursive
make[1]: Entering directory '/home/todns/Projects/janus-gateway'
Making all in html
make[2]: Entering directory '/home/todns/Projects/janus-gateway/html'
make[2]: Nothing to be done for 'all'.
make[2]: Leaving directory '/home/todns/Projects/janus-gateway/html'
make[2]: Entering directory '/home/todns/Projects/janus-gateway'
  CCLD     janus
db/janus-connect.o: In function `connect_to_database':
/home/todns/Projects/janus-gateway/db/connect.c:20: undefined reference to `PQconnectdb'
collect2: error: ld returned 1 exit status
Makefile:1195: recipe for target 'janus' failed
make[2]: *** [janus] Error 1
make[2]: Leaving directory '/home/todns/Projects/janus-gateway'
Makefile:1914: recipe for target 'all-recursive' failed
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory '/home/todns/Projects/janus-gateway'
Makefile:905: recipe for target 'all' failed
make: *** [all] Error 2

问题是：

db/janus-connect.o: In function `connect_to_database':
    /home/todns/Projects/janus-gateway/db/connect.c:20: undefined

我的直觉告诉我，这与Makefile.am文件有关，但我真的不知道该改变什么。所以问题是:我在这个设置中遗漏了什么？如何将postgres库与我的C代码链接？

谢谢!

编辑：忘了提到，我是在Linux虚拟机上运行的(主机器是macbook )。

Answer 1

弄明白了。

将-L/.... -psql附加到AM_CFLAGS Makefile.am

以下是整行内容：

AM_CFLAGS += -fstack-protector-all -g -ggdb -fPIC -rdynamic -pthread -L/usr/include/postgresql/libpq -lpq

您可以查看janus-网关Makefile.am，看看我的Makefile.am在没有-psql的情况下是什么样子。