How to get a pointer to a binary section in MSVC?

user_459957 0
Viewed 3399

I'm writing some code which stores some data structures in a special named binary section. These are all instances of the same struct which are scattered across many C files and are not within scope of each other. By placing them all in the named section I can iterate over all of them.

In GCC, I use _attribute_((section(...)) plus some specially named extern pointers which are magically filled in by the linker. Here's a trivial example:

#include <stdio.h>

extern int __start___mysection[];
extern int __stop___mysection[];

static int x __attribute__((section("__mysection"))) = 4;
static int y __attribute__((section("__mysection"))) = 10;
static int z __attribute__((section("__mysection"))) = 22;

#define SECTION_SIZE(sect) \
    ((size_t)((__stop_##sect - __start_##sect)))

int main(void)
{
    size_t sz = SECTION_SIZE(__mysection);
    int i;

    printf("Section size is %u\n", sz);

    for (i=0; i < sz; i++) {
        printf("%d\n", __start___mysection[i]);
    }

    return 0;
}

I'm trying to figure out how to do this in MSVC but I'm drawing a blank. I see from the compiler documentation that I can declare the section using __pragma(section(...)) and declare data to be in that section with __declspec(allocate(...)) but I can't see how I can get a pointer to the start and end of the section at runtime.

I've seen some examples on the web related to doing _attribute_((constructor)) in MSVC, but it seems like hacking specific to CRT and not a general way to get a pointer to the beginning/end of a section. Anyone have any ideas?

linker gcc visual-c++ c
4 Answers

ML64 allows to cut a lot of the assembly noise :

public foo_start
public foo_stop

.code foo$a
foo_start:

.code foo$z
foo_stop:

end
user_1081720
Related