Commit c5e4a5a9 authored by Magnus Reftel's avatar Magnus Reftel Committed by Riku Voipio
Browse files

linux-user: Let user specify random seed 



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: default avatarMagnus Reftel <reftel@spotify.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarRiku Voipio <riku.voipio@linaro.org>
parent 0a2923f8

linux-user/elfload.c

+0 −1
Original line number Diff line number Diff line
@@ -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();

    }

linux-user/main.c

+19 −0
Original line number Diff line number Diff line
@@ -3546,6 +3546,17 @@ static void handle_arg_pagesize(const char *arg) 
    }

}



static void handle_arg_randseed(const char *arg)

{

    unsigned long long seed;



    if (parse_uint_full(arg, &seed, 0) != 0 || seed > UINT_MAX) {

        fprintf(stderr, "Invalid seed number: %s\n", arg);

        exit(1);

    }

    srand(seed);

}



static void handle_arg_gdb(const char *arg)

{

    gdbstub_port = atoi(arg);
@@ -3674,6 +3685,8 @@ 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}
@@ -3856,6 +3869,8 @@ int main(int argc, char **argv, char **envp) 
    cpudef_setup(); /* parse cpu definitions in target config file (TBD) */

#endif



    srand(time(NULL));



    optind = parse_args(argc, argv);



    /* Zero out regs */
@@ -3926,6 +3941,10 @@ int main(int argc, char **argv, char **envp) 
        do_strace = 1;

    }



    if (getenv("QEMU_RAND_SEED")) {

        handle_arg_randseed(getenv("QEMU_RAND_SEED"));

    }



    target_environ = envlist_to_environ(envlist, NULL);

    envlist_free(envlist);