github.com/afumu/libc@v0.0.6/musl/src/internal/fdpic_crt.h (about)

     1  #include <stdint.h>
     2  #include <features.h>
     3  
     4  hidden void *__fdpic_fixup(void *map, uintptr_t *a, uintptr_t *z)
     5  {
     6  	/* If map is a null pointer, the program was loaded by a
     7  	 * non-FDPIC-aware ELF loader, and fixups are not needed,
     8  	 * but the value for the GOT pointer is. */
     9  	if (!map) return (void *)z[-1];
    10  
    11  	struct {
    12  		unsigned short version, nsegs;
    13  		struct fdpic_loadseg {
    14  			uintptr_t addr, p_vaddr, p_memsz;
    15  		} segs[];
    16  	} *lm = map;
    17  	int nsegs = lm->nsegs, rseg = 0, vseg = 0;
    18  	for (;;) {
    19  		while (*a-lm->segs[rseg].p_vaddr >= lm->segs[rseg].p_memsz)
    20  			if (++rseg == nsegs) rseg = 0;
    21  		uintptr_t *r = (uintptr_t *)
    22  			(*a + lm->segs[rseg].addr - lm->segs[rseg].p_vaddr);
    23  		if (++a == z) return r;
    24  		while (*r-lm->segs[vseg].p_vaddr >= lm->segs[vseg].p_memsz)
    25  			if (++vseg == nsegs) vseg = 0;
    26  		*r += lm->segs[vseg].addr - lm->segs[vseg].p_vaddr;
    27  	}
    28  }