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author | fishsoupisgood <github@madingley.org> | 2019-04-29 01:17:54 +0100 |
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committer | fishsoupisgood <github@madingley.org> | 2019-05-27 03:43:43 +0100 |
commit | 3f2546b2ef55b661fd8dd69682b38992225e86f6 (patch) | |
tree | 65ca85f13617aee1dce474596800950f266a456c /util/getauxval.c | |
download | qemu-master.tar.gz qemu-master.tar.bz2 qemu-master.zip |
Diffstat (limited to 'util/getauxval.c')
-rw-r--r-- | util/getauxval.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/util/getauxval.c b/util/getauxval.c new file mode 100644 index 00000000..1732ace2 --- /dev/null +++ b/util/getauxval.c @@ -0,0 +1,109 @@ +/* + * QEMU access to the auxiliary vector + * + * Copyright (C) 2013 Red Hat, Inc + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "qemu-common.h" +#include "qemu/osdep.h" + +#ifdef CONFIG_GETAUXVAL +/* Don't inline this in qemu/osdep.h, because pulling in <sys/auxv.h> for + the system declaration of getauxval pulls in the system <elf.h>, which + conflicts with qemu's version. */ + +#include <sys/auxv.h> + +unsigned long qemu_getauxval(unsigned long key) +{ + return getauxval(key); +} +#elif defined(__linux__) +#include "elf.h" + +/* Our elf.h doesn't contain Elf32_auxv_t and Elf64_auxv_t, which is ok because + that just makes it easier to define it properly for the host here. */ +typedef struct { + unsigned long a_type; + unsigned long a_val; +} ElfW_auxv_t; + +static const ElfW_auxv_t *auxv; + +static const ElfW_auxv_t *qemu_init_auxval(void) +{ + ElfW_auxv_t *a; + ssize_t size = 512, r, ofs; + int fd; + + /* Allocate some initial storage. Make sure the first entry is set + to end-of-list, so that we've got a valid list in case of error. */ + auxv = a = g_malloc(size); + a[0].a_type = 0; + a[0].a_val = 0; + + fd = open("/proc/self/auxv", O_RDONLY); + if (fd < 0) { + return a; + } + + /* Read the first SIZE bytes. Hopefully, this covers everything. */ + r = read(fd, a, size); + + if (r == size) { + /* Continue to expand until we do get a partial read. */ + do { + ofs = size; + size *= 2; + auxv = a = g_realloc(a, size); + r = read(fd, (char *)a + ofs, ofs); + } while (r == ofs); + } + + close(fd); + return a; +} + +unsigned long qemu_getauxval(unsigned long type) +{ + const ElfW_auxv_t *a = auxv; + + if (unlikely(a == NULL)) { + a = qemu_init_auxval(); + } + + for (; a->a_type != 0; a++) { + if (a->a_type == type) { + return a->a_val; + } + } + + return 0; +} + +#else + +unsigned long qemu_getauxval(unsigned long type) +{ + return 0; +} + +#endif |