Glusterfs的编译选项 #pragma GCC poison system popen

       最近一直在研究Glusterfs3.3.1，当因需在代码中加入system（cmd）调用时，编译器提示error：attempt to use poisoned ”system"，即试图使用有毒的system调用，首先我检查了一遍代码，其实就是一个system调用。排除了代码编写错误。然后我突然想起了system调用需要慎用的，调用system的进程在调用system未返回时可能会阻塞而且会忽略某几种信号。我接下来在网上查了查资料，确实system调用时可能会有诸多问题。 

        我在Glusterfs的源码文件./libglusterfs/src/compat.h也找到了这句话：#pragma GCC poison system popen，所以，当我再代码中加入system，popen等调用时，编译器就会报错，禁止编译。

        问题又来了.我是自己编码实现类system的功能还是Glusterfs另有解决的办法的？显然，Glusterfs的研发团队足够的聪明，我们想的他们都替我们想好了，哈哈。在libglusterfs/src/下有run.h，实现了类system调用的接口runcmd等，且 使用非常灵活。run.h接口声明如下：

/*
   Copyright (c) 2008-2012 Red Hat, Inc. <http://www.redhat.com>
   This file is part of GlusterFS.
   This file is licensed to you under your choice of the GNU Lesser
   General Public License, version 3 or any later version (LGPLv3 or
   later), or the GNU General Public License, version 2 (GPLv2), in all
   cases as published by the Free Software Foundation.
 */
 #ifndef __RUN_H__
 #define __RUN_H__
 #define RUN_PIPE -1
 struct runner {
         char **argv;
         unsigned argvlen;
         int runerr;
         pid_t chpid;
         int chfd[3];
         FILE *chio[3];
 };
 typedef struct runner runner_t;
 /**
 * initialize runner_t instance.
 *
 * @param runner pointer to runner_t instance
 */
 void runinit (runner_t *runner);
 /**
 * get FILE pointer to which child's stdio is redirected.
 *
 * @param runner pointer to runner_t instance
 * @param fd specifies which standard file descriptor is
 *        is asked for
 *
 * @see runner_redir()
 */
 FILE *runner_chio (runner_t *runner, int fd);
 /**
 * add an argument.
 *
 * 'arg' is duplicated.
 *
 * Errors are deferred, no error handling is necessary.
 *
 * @param runner pointer to runner_t instance
 * @param arg    command line argument
 */
 void runner_add_arg (runner_t *runner, const char *arg);
 /**
 * add a sequence of arguments.
 *
 * Variadic function, calls runner_add_arg() on each vararg.
 * Argument sequence MUST be NULL terminated.
 *
 * Errors are deferred, no error handling is necessary.
 *
 * @param runner pointer to runner_t instance
 *
 * @see runner_add_arg()
 */
 void runner_add_args (runner_t *runner, ...);
 /**
 * add an argument with printf style formatting.
 *
 * Errors are deferred, no error handling is necessary.
 *
 * @param runner pointer to runner_t instance
 * @param format printf style format specifier
 */
 void runner_argprintf (runner_t *runner, const char *format, ...);
 /**
 * log a message about the command to be run.
 *
 * @param runner  pointer to runner_t instance
 *
 * @param dom  log domain
 * @param lvl  log level
 * @param msg  message with which the command is prefixed in log
 *
 * @see gf_log()
 */
 void runner_log (runner_t *runner, const char *dom, gf_loglevel_t lvl,
                  const char *msg);
 /**
 * set up redirection for child.
 *
 * @param runner  pointer to runner_t instance
 *
 * @param fd      fd of child to redirect (0, 1, or 2)
 * @param tgt_fd  fd on parent side to redirect to.
 *                Note that runner_end() will close tgt_fd,
 *                if user needs it in another context it should
 *                be dup'd beforehand.
 *                RUN_PIPE can be used for requiring a
 *                pipe from child to parent. The FILE
 *                created for this purpose will be
 *                accessible via runner_chio() (after
 *                runner_start() has been invoked).
 *
 * @see  runner_start(), dup(2), runner_chio(), runner_start()
 */
 void
 runner_redir (runner_t *runner, int fd, int tgt_fd);
 /**
 * spawn child with accumulated arg list.
 *
 * @param runner  pointer to runner_t instance
 *
 * @return  0 on succesful spawn
 *          -1 on failure (either due to earlier errors or execve(2) failing)
 *
 * @see runner_cout()
 */
 int runner_start (runner_t *runner);
 /**
 * complete operation and free resources.
 *
 * If child exists, waits for it. Redirections will be closed.
 * Dynamically allocated memory shall be freed.
 *
 * @param runner  pointer to runner_t instance
 *
 * @return  0 if child terminated successfully
 *          -1 if there is no running child
 *          n > 0 if child failed; value to be interpreted as status
 *                in waitpid(2)
 *
 * @see waitpid(2)
 */
 int runner_end (runner_t *runner);
 /**
 * variant of runner_end() which does not free internal data
 * so that the runner instance can be run again.
 *
 * @see runner_end()
 */
 int runner_end_reuse (runner_t *runner);
 /**
 * spawn and child, take it to completion and free resources.
 *
 * Essentially it's a concatenation of runner_start() and runner_end()
 * with simplified return semantics.
 *
 * @param runner  pointer to runner_t instance
 *
 * @return  0 on success
 *          -1 on failuire
 *
 * @see runner_start(), runner_end()
 */
 int runner_run (runner_t *runner);
 /**
 * variant of runner_run() which does not free internal data
 * so that the runner instance can be run again.
 *
 * @see runner_run()
 */
 int runner_run_reuse (runner_t *runner);
 /**
 * run a command with args.
 *
 * Variadic function, child process is spawned with
 * the given sequence of args and waited for.
 * Argument sequence MUST be NULL terminated.
 *
 * @return 0 on success
 *         -1 on failure
 */
 int runcmd (const char *arg, ...);
 #endif
 

       例如：我在代码中想这样用：system("echo hello world!");，用runcmd实现则这样用：runcmd("echo", "hello", "world!", NULL);在run.h中还有更灵活的接口，而且在同目录的run.c文件中对run.h的接口都有使用实例，在此不做赘述。        

 

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