如何编译这个C程序?

When I type gcc gprof-helper.c to compile the program I get these errors:

当我输入gcc gprof-helper。c为了编译程序，我得到以下错误:

gprof-helper.c: In function `wooinit':
gprof-helper.c:38: error: `RTLD_NEXT' undeclared (first use in this function)
gprof-helper.c:38: error: (Each undeclared identifier is reported only once
gprof-helper.c:38: error: for each function it appears in.)

This is the program file:

这是程序文件:

#define _GNU_SOURCE
#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>
#include <pthread.h>

static void * wrapper_routine(void *);

/* Original pthread function */
static int (*pthread_create_orig)(pthread_t *__restrict,
                                  __const pthread_attr_t *__restrict,
                                  void *(*)(void *),
                                  void *__restrict) = NULL;

/* Library initialization function */
void wooinit(void) __attribute__((constructor));

void wooinit(void)
{
    pthread_create_orig = dlsym(RTLD_NEXT, "pthread_create");
    fprintf(stderr, "pthreads: using profiling hooks for gprof\n");
    if(pthread_create_orig == NULL)
    {
        char *error = dlerror();
        if(error == NULL)
        {
            error = "pthread_create is NULL";
        }
        fprintf(stderr, "%s\n", error);
        exit(EXIT_FAILURE);
    }
}

/* Our data structure passed to the wrapper */
typedef struct wrapper_s
{
    void * (*start_routine)(void *);
    void * arg;

    pthread_mutex_t lock;
    pthread_cond_t  wait;

    struct itimerval itimer;

} wrapper_t;

/* The wrapper function in charge for setting the itimer value */
static void * wrapper_routine(void * data)
{
    /* Put user data in thread-local variables */
    void * (*start_routine)(void *) = ((wrapper_t*)data)->start_routine;
    void * arg = ((wrapper_t*)data)->arg;

    /* Set the profile timer value */
    setitimer(ITIMER_PROF, &((wrapper_t*)data)->itimer, NULL);

    /* Tell the calling thread that we don't need its data anymore */
    pthread_mutex_lock(&((wrapper_t*)data)->lock);
    pthread_cond_signal(&((wrapper_t*)data)->wait);
    pthread_mutex_unlock(&((wrapper_t*)data)->lock);

    /* Call the real function */
    return start_routine(arg);
}

/* Our wrapper function for the real pthread_create() */
int pthread_create(pthread_t *__restrict thread,
                   __const pthread_attr_t *__restrict attr,
                   void * (*start_routine)(void *),
                   void *__restrict arg)
{
    wrapper_t wrapper_data;
    int i_return;

    /* Initialize the wrapper structure */
    wrapper_data.start_routine = start_routine;
    wrapper_data.arg = arg;
    getitimer(ITIMER_PROF, &wrapper_data.itimer);
    pthread_cond_init(&wrapper_data.wait, NULL);
    pthread_mutex_init(&wrapper_data.lock, NULL);
    pthread_mutex_lock(&wrapper_data.lock);

    /* The real pthread_create call */
    i_return = pthread_create_orig(thread,
                                   attr,
                                   &wrapper_routine,
                                   &wrapper_data);

    /* If the thread was successfully spawned, wait for the data
     * to be released */
    if(i_return == 0)
    {
        pthread_cond_wait(&wrapper_data.wait, &wrapper_data.lock);
    }

    pthread_mutex_unlock(&wrapper_data.lock);
    pthread_mutex_destroy(&wrapper_data.lock);
    pthread_cond_destroy(&wrapper_data.wait);

    return i_return;
}

How do I get rid of those errors?

我怎样才能避免这些错误呢?

1 个解决方案

#1

RTLD_NEXT has been available in glibc since time immemorial.
Are you building on a Linux (or glibc-based) system? Doesn't sound like it.

RTLD_NEXT从很久以前就在glibc中可用了。您正在构建Linux(或基于glibc的)系统吗?听起来不像。

Update:
RTLD_NEXT is a glibc extension. You can't use it on cygwin, because cygwin != glibc.
As far as I understand, cygwin doesn't support LD_PRELOAD either, so even if you succeeded in building this library, it wouldn't be very useful.

更新:RTLD_NEXT是一个glibc扩展。你不能在cygwin上使用它，因为cygwin != glibc。据我所知，cygwin也不支持LD_PRELOAD，因此即使您成功构建了这个库，它也不是很有用。