util/getauxval.c

   1 /*
   2  * QEMU access to the auxiliary vector
   3  *
   4  * Copyright (C) 2013 Red Hat, Inc
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu-common.h"
  26 #include "qemu/osdep.h"
  27
  28 #ifdef CONFIG_GETAUXVAL
  29 /* Don't inline this in qemu/osdep.h, because pulling in <sys/auxv.h> for
  30    the system declaration of getauxval pulls in the system <elf.h>, which
  31    conflicts with qemu's version.  */
  32
  33 #include <sys/auxv.h>
  34
  35 unsigned long qemu_getauxval(unsigned long key)
  36 {
  37     return getauxval(key);
  38 }
  39 #elif defined(__linux__)
  40 #include "elf.h"
  41
  42 /* Our elf.h doesn't contain Elf32_auxv_t and Elf64_auxv_t, which is ok because
  43    that just makes it easier to define it properly for the host here.  */
  44 typedef struct {
  45     unsigned long a_type;
  46     unsigned long a_val;
  47 } ElfW_auxv_t;
  48
  49 static const ElfW_auxv_t *auxv;
  50
  51 void qemu_init_auxval(char **envp)
  52 {
  53     /* The auxiliary vector is located just beyond the initial environment.  */
  54     while (*envp++ != NULL) {
  55         continue;
  56     }
  57     auxv = (const ElfW_auxv_t *)envp;
  58 }
  59
  60 unsigned long qemu_getauxval(unsigned long type)
  61 {
  62     /* If we were able to find the auxiliary vector, use it.  */
  63     if (auxv) {
  64         const ElfW_auxv_t *a;
  65         for (a = auxv; a->a_type != 0; a++) {
  66             if (a->a_type == type) {
  67                 return a->a_val;
  68             }
  69         }
  70     }
  71
  72     return 0;
  73 }
  74 #endif