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[Qemu-devel] [PATCH] linux-user: Let user specify random seed
From: |
Magnus Reftel |
Subject: |
[Qemu-devel] [PATCH] linux-user: Let user specify random seed |
Date: |
Wed, 8 Oct 2014 14:13:54 +0200 |
This patch introduces the -seed command line option and the
QEMU_RAND_SEED environment variable for setting the random seed, which
is used for the AT_RANDOM ELF aux entry.
Signed-off-by: Magnus Reftel <address@hidden>
---
linux-user/elfload.c | 1 -
linux-user/main.c | 21 +++++++++++++++++++++
2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 1c04fcf..f2e2197 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -1539,7 +1539,6 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc,
int envc,
* Generate 16 random bytes for userspace PRNG seeding (not
* cryptically secure but it's not the aim of QEMU).
*/
- srand((unsigned int) time(NULL));
for (i = 0; i < 16; i++) {
k_rand_bytes[i] = rand();
}
diff --git a/linux-user/main.c b/linux-user/main.c
index 483eb3f..57cd721 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -46,6 +46,8 @@ unsigned long mmap_min_addr;
#if defined(CONFIG_USE_GUEST_BASE)
unsigned long guest_base;
int have_guest_base;
+static bool have_rand_seed = false;
+static int rand_seed;
#if (TARGET_LONG_BITS == 32) && (HOST_LONG_BITS == 64)
/*
* When running 32-on-64 we should make sure we can fit all of the possible
@@ -3546,6 +3548,12 @@ static void handle_arg_pagesize(const char *arg)
}
}
+static void handle_arg_randseed(const char *arg)
+{
+ have_rand_seed = true;
+ rand_seed = atoi(arg);
+}
+
static void handle_arg_gdb(const char *arg)
{
gdbstub_port = atoi(arg);
@@ -3674,6 +3682,8 @@ static const struct qemu_argument arg_table[] = {
"", "run in singlestep mode"},
{"strace", "QEMU_STRACE", false, handle_arg_strace,
"", "log system calls"},
+ {"seed", "QEMU_RAND_SEED", true, handle_arg_randseed,
+ "", "Seed for pseudo-random number generator"},
{"version", "QEMU_VERSION", false, handle_arg_version,
"", "display version information and exit"},
{NULL, NULL, false, NULL, NULL, NULL}
@@ -3926,6 +3936,17 @@ int main(int argc, char **argv, char **envp)
do_strace = 1;
}
+ if (getenv("QEMU_RAND_SEED")) {
+ have_rand_seed = true;
+ rand_seed = atoi(getenv("QEMU_RAND_SEED"));
+ }
+
+ if (have_rand_seed) {
+ srand(rand_seed);
+ } else {
+ srand((int)time(NULL));
+ }
+
target_environ = envlist_to_environ(envlist, NULL);
envlist_free(envlist);
--
1.9.1