qemu

FORK: QEMU emulator
git clone https://git.neptards.moe/neptards/qemu.git
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getauxval.c (3200B)

      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/osdep.h"
     26 
     27 #ifdef CONFIG_GETAUXVAL
     28 /* Don't inline this in qemu/osdep.h, because pulling in <sys/auxv.h> for
     29    the system declaration of getauxval pulls in the system <elf.h>, which
     30    conflicts with qemu's version.  */
     31 
     32 #include <sys/auxv.h>
     33 
     34 unsigned long qemu_getauxval(unsigned long key)
     35 {
     36     return getauxval(key);
     37 }
     38 #elif defined(__linux__)
     39 #include "elf.h"
     40 
     41 /* Our elf.h doesn't contain Elf32_auxv_t and Elf64_auxv_t, which is ok because
     42    that just makes it easier to define it properly for the host here.  */
     43 typedef struct {
     44     unsigned long a_type;
     45     unsigned long a_val;
     46 } ElfW_auxv_t;
     47 
     48 static const ElfW_auxv_t *auxv;
     49 
     50 static const ElfW_auxv_t *qemu_init_auxval(void)
     51 {
     52     ElfW_auxv_t *a;
     53     ssize_t size = 512, r, ofs;
     54     int fd;
     55 
     56     /* Allocate some initial storage.  Make sure the first entry is set
     57        to end-of-list, so that we've got a valid list in case of error.  */
     58     auxv = a = g_malloc(size);
     59     a[0].a_type = 0;
     60     a[0].a_val = 0;
     61 
     62     fd = open("/proc/self/auxv", O_RDONLY);
     63     if (fd < 0) {
     64         return a;
     65     }
     66 
     67     /* Read the first SIZE bytes.  Hopefully, this covers everything.  */
     68     r = read(fd, a, size);
     69 
     70     if (r == size) {
     71         /* Continue to expand until we do get a partial read.  */
     72         do {
     73             ofs = size;
     74             size *= 2;
     75             auxv = a = g_realloc(a, size);
     76             r = read(fd, (char *)a + ofs, ofs);
     77         } while (r == ofs);
     78     }
     79 
     80     close(fd);
     81     return a;
     82 }
     83 
     84 unsigned long qemu_getauxval(unsigned long type)
     85 {
     86     const ElfW_auxv_t *a = auxv;
     87 
     88     if (unlikely(a == NULL)) {
     89         a = qemu_init_auxval();
     90     }
     91 
     92     for (; a->a_type != 0; a++) {
     93         if (a->a_type == type) {
     94             return a->a_val;
     95         }
     96     }
     97 
     98     return 0;
     99 }
    100 
    101 #elif defined(__FreeBSD__)
    102 #include <sys/auxv.h>
    103 
    104 unsigned long qemu_getauxval(unsigned long type)
    105 {
    106     unsigned long aux = 0;
    107     elf_aux_info(type, &aux, sizeof(aux));
    108     return aux;
    109 }
    110 
    111 #else
    112 
    113 unsigned long qemu_getauxval(unsigned long type)
    114 {
    115     return 0;
    116 }
    117 
    118 #endif