Archipelago » qemu

/* User memory access */

#include <stdio.h>

#include <string.h>

#include "qemu.h"

/* copy_from_user() and copy_to_user() are usually used to copy data

 * buffers between the target and host.  These internally perform

 * locking/unlocking of the memory.

 */

abi_long copy_from_user(void *hptr, abi_ulong gaddr, size_t len)

{

    abi_long ret = 0;

    void *ghptr;

    if ((ghptr = lock_user(VERIFY_READ, gaddr, len, 1))) {

        memcpy(hptr, ghptr, len);

        unlock_user(ghptr, gaddr, 0);

    } else

        ret = -TARGET_EFAULT;

    return ret;

}

abi_long copy_to_user(abi_ulong gaddr, void *hptr, size_t len)

{

    abi_long ret = 0;

    void *ghptr;

    if ((ghptr = lock_user(VERIFY_WRITE, gaddr, len, 0))) {

        memcpy(ghptr, hptr, len);

        unlock_user(ghptr, gaddr, len);

    } else

        ret = -TARGET_EFAULT;

    return ret;

}

/* XXX: use host strnlen if available ? */

static int qemu_strnlen(const char *s, int max_len)

{

    int i;

    for(i = 0; i < max_len; i++) {

        if (s[i] == '\0')

            break;

    }

    return i;

}

/* Return the length of a string in target memory or -TARGET_EFAULT if

   access error  */

abi_long target_strlen(abi_ulong guest_addr1)

{

    uint8_t *ptr;

    abi_ulong guest_addr;

    int max_len, len;

    guest_addr = guest_addr1;

    for(;;) {

        max_len = TARGET_PAGE_SIZE - (guest_addr & ~TARGET_PAGE_MASK);

        ptr = lock_user(VERIFY_READ, guest_addr, max_len, 1);

        if (!ptr)

            return -TARGET_EFAULT;

        len = qemu_strnlen((const char *)ptr, max_len);

        unlock_user(ptr, guest_addr, 0);

        guest_addr += len;

        /* we don't allow wrapping or integer overflow */

        if (guest_addr == 0 || 

            (guest_addr - guest_addr1) > 0x7fffffff)

            return -TARGET_EFAULT;

        if (len != max_len)

            break;

    }

    return guest_addr - guest_addr1;

}