dtrace discuss - Apr 2006 - Accessing an userland structure

check_clients (cmd/fs.d/nfs/mountd/mountd.c) has the following parameters:

static int
check_client_new(struct share *sh, struct netbuf *nb,
    struct nd_hostservlist *clnames, int flavor)

And,

struct share {
        char *sh_path;
        char *sh_res;
        char *sh_fstype;
        char *sh_opts;
        char *sh_descr;
};

So if I have a probe to access the first variable, I''ll have to get the
structure into memory first and then the contents of the strings. Something
like:

        sh = (struct share *)copyin(arg0, sizeof(struct share));
        printf("|%s|%s|%s|%s|%s\n",
                (string)copyinstr((uintptr_t)sh->sh_path),
                (string)copyinstr((uintptr_t)sh->sh_res),
                (string)copyinstr((uintptr_t)sh->sh_fstype),
                (string)copyinstr((uintptr_t)sh->sh_opts),
                (string)copyinstr((uintptr_t)sh->sh_descr));

When I try this, I get messages of the form:

dtrace: error on enabled probe ID 15 (ID 40983:
pid101148:mountd:check_client:entry): invalid address (0x2e000) in action #4 at
DIF offset 16

What is this telling me?
 
 
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