Question

I write the code below to test the talloc:

#include "talloc.h"

typedef struct linklist
{
    char* str;
    struct linklist* next;
}LinkList;

int main(int argc,char* argv[])
{
    LinkList* lptr=talloc(NULL,LinkList);
    lptr->str=talloc_strdup(lptr,"Test ptr");

    talloc_free(lptr);

    return 0;
}

But got compile error:

talloctest.c:(.text+0x21): undefined reference to `talloc_named_const(void const*, unsigned int, char const*)'
talloctest.c:(.text+0x39): undefined reference to `talloc_strdup(void const*, char const*)'
talloctest.c:(.text+0x4d): undefined reference to `talloc_free(void*)'
collect2: ld returned 1 exit status

Then I find the definition of relative macros and functions:
Definition in “talloc.h”:

#define talloc(ctx, type) (type *)talloc_named_const(ctx, sizeof(type), #type)
char *talloc_strdup(const void *t, const char *p);

Implemetation in “talloc.c”:

void *talloc_named_const(const void *context, size_t size, const char *name)
{
    return _talloc_named_const(context, size, name);
}

char *talloc_strdup(const void *t, const char *p)
{
    if (unlikely(!p)) return NULL;
    return __talloc_strlendup(t, p, strlen(p));
}

Can someone tell me why?I have tried both talloc-1.3.0 and talloc-2.0.7,but got the same result.

Answer 1

Are you using talloc as a separate library or compiling it into your executable? If you’re using it as a separate library, you’ll need to link to it – at a guess by adding -ltalloc to your build command.