libc-top-half/musl/src/ldso/dl_iterate_phdr.c

   1 #include <elf.h>
   2 #include <link.h>
   3 #include "pthread_impl.h"
   4 #include "libc.h"
   5
   6 #define AUX_CNT 38
   7
   8 extern weak hidden const size_t _DYNAMIC[];
   9
  10 static int static_dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
  11 {
  12         unsigned char *p;
  13         ElfW(Phdr) *phdr, *tls_phdr=0;
  14         size_t base = 0;
  15         size_t n;
  16         struct dl_phdr_info info;
  17         size_t i, aux[AUX_CNT] = {0};
  18
  19         for (i=0; libc.auxv[i]; i+=2)
  20                 if (libc.auxv[i]<AUX_CNT) aux[libc.auxv[i]] = libc.auxv[i+1];
  21
  22         for (p=(void *)aux[AT_PHDR],n=aux[AT_PHNUM]; n; n--,p+=aux[AT_PHENT]) {
  23                 phdr = (void *)p;
  24                 if (phdr->p_type == PT_PHDR)
  25                         base = aux[AT_PHDR] - phdr->p_vaddr;
  26                 if (phdr->p_type == PT_DYNAMIC && _DYNAMIC)
  27                         base = (size_t)_DYNAMIC - phdr->p_vaddr;
  28                 if (phdr->p_type == PT_TLS)
  29                         tls_phdr = phdr;
  30         }
  31         info.dlpi_addr  = base;
  32         info.dlpi_name  = "/proc/self/exe";
  33         info.dlpi_phdr  = (void *)aux[AT_PHDR];
  34         info.dlpi_phnum = aux[AT_PHNUM];
  35         info.dlpi_adds  = 0;
  36         info.dlpi_subs  = 0;
  37         if (tls_phdr) {
  38                 info.dlpi_tls_modid = 1;
  39                 info.dlpi_tls_data = __tls_get_addr((tls_mod_off_t[]){1,0});
  40         } else {
  41                 info.dlpi_tls_modid = 0;
  42                 info.dlpi_tls_data = 0;
  43         }
  44         return (callback)(&info, sizeof (info), data);
  45 }
  46
  47 weak_alias(static_dl_iterate_phdr, dl_iterate_phdr);