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qemu/osdep: Remove the need for qemu_init_auxval

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Instead of getting backup auxv data from the env pointer given to main,
read it from /proc/self/auxv.  We can do this at any time, so we're not
tied to any ordering wrt a call to qemu_init_auxval from main.

Tested-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2014-04-30 13:49:11 -07:00
parent 40d964b563
commit 2b45c3f500
4 changed files with 39 additions and 26 deletions
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51
util/getauxval.c
View file

@ -48,24 +48,51 @@ typedef struct {
static const ElfW_auxv_t *auxv;
void qemu_init_auxval(char **envp)
static const ElfW_auxv_t *qemu_init_auxval(void)
{
/* The auxiliary vector is located just beyond the initial environment. */
while (*envp++ != NULL) {
continue;
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;
}
auxv = (const ElfW_auxv_t *)envp;
/* 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)
{
/* If we were able to find the auxiliary vector, use it. */
if (auxv) {
const ElfW_auxv_t *a;
for (a = auxv; a->a_type != 0; a++) {
if (a->a_type == type) {
return a->a_val;
}
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;
}
}