lock_iovec will lock an I/O vec and the memory to which it referrs and
create a iovec in the host space that referrs to it, with full error
unwinding.
Signed-off-by: Warner Losh <i...@bsdimp.com>
---
bsd-user/freebsd/os-syscall.c | 92 +++++++++++++++++++++++++++++++++++
1 file changed, 92 insertions(+)
diff --git a/bsd-user/freebsd/os-syscall.c b/bsd-user/freebsd/os-syscall.c
index 060134a9ecd..c21759ae7ce 100644
--- a/bsd-user/freebsd/os-syscall.c
+++ b/bsd-user/freebsd/os-syscall.c
@@ -75,6 +75,98 @@ bool is_error(abi_long ret)
return (abi_ulong)ret >= (abi_ulong)(-4096);
}
+struct iovec *lock_iovec(int type, abi_ulong target_addr,
+ int count, int copy)
+{
+ struct target_iovec *target_vec;
+ struct iovec *vec;
+ abi_ulong total_len, max_len;
+ int i;
+ int err = 0;
+ bool bad_address = false;
+
+ if (count == 0) {
+ errno = 0;
+ return NULL;
+ }
+ if (count < 0 || count > IOV_MAX) {
+ errno = EINVAL;
+ return NULL;
+ }
+
+ vec = calloc(count, sizeof(struct iovec));
+ if (vec == NULL) {
+ errno = ENOMEM;
+ return NULL;
+ }
+
+ target_vec = lock_user(VERIFY_READ, target_addr,
+ count * sizeof(struct target_iovec), 1);
+ if (target_vec == NULL) {
+ err = EFAULT;
+ goto fail2;
+ }
+
+ /*
+ * ??? If host page size > target page size, this will result in a value
+ * larger than what we can actually support.
+ */
+ max_len = 0x7fffffff & TARGET_PAGE_MASK;
+ total_len = 0;
+
+ for (i = 0; i < count; i++) {
+ abi_ulong base = tswapal(target_vec[i].iov_base);
+ abi_long len = tswapal(target_vec[i].iov_len);
+
+ if (len < 0) {
+ err = EINVAL;
+ goto fail;
+ } else if (len == 0) {
+ /* Zero length pointer is ignored. */
+ vec[i].iov_base = 0;
+ } else {
+ vec[i].iov_base = lock_user(type, base, len, copy);
+ /*
+ * If the first buffer pointer is bad, this is a fault. But
+ * subsequent bad buffers will result in a partial write; this is
+ * realized by filling the vector with null pointers and zero
+ * lengths.
+ */
+ if (!vec[i].iov_base) {
+ if (i == 0) {
+ err = EFAULT;
+ goto fail;
+ } else {
+ bad_address = true;
+ }
+ }
+ if (bad_address) {
+ len = 0;
+ }
+ if (len > max_len - total_len) {
+ len = max_len - total_len;
+ }
+ }
+ vec[i].iov_len = len;
+ total_len += len;
+ }
+
+ unlock_user(target_vec, target_addr, 0);
+ return vec;
+
+ fail:
+ while (--i >= 0) {
+ if (tswapal(target_vec[i].iov_len) > 0) {
+ unlock_user(vec[i].iov_base, tswapal(target_vec[i].iov_base), 0);
+ }
+ }
+ unlock_user(target_vec, target_addr, 0);
+ fail2:
+ free(vec);
+ errno = err;
+ return NULL;
+}
+
/*
* do_syscall() should always have a single exit point at the end so that
* actions, such as logging of syscall results, can be performed. All errnos
--
2.33.1
