raw-format: Split raw_read_options()

Split raw_read_options() into one function that actually just reads the
options, and another that applies them.  This will allow us to detect
whether the user has specified any options before attaching the file
child (so we can decide on its role based on the options).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200513110544.176672-21-mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/raw-format.c

@@ -71,20 +71,13 @@ static QemuOptsList raw_create_opts = {
     }
 };
 
-static int raw_read_options(QDict *options, BlockDriverState *bs,
-    BDRVRawState *s, Error **errp)
+static int raw_read_options(QDict *options, uint64_t *offset, bool *has_size,
+                            uint64_t *size, Error **errp)
 {
     Error *local_err = NULL;
     QemuOpts *opts = NULL;
-    int64_t real_size = 0;
     int ret;
 
-    real_size = bdrv_getlength(bs->file->bs);
-    if (real_size < 0) {
-        error_setg_errno(errp, -real_size, "Could not get image size");
-        return real_size;
-    }
-
     opts = qemu_opts_create(&raw_runtime_opts, NULL, 0, &error_abort);
     qemu_opts_absorb_qdict(opts, options, &local_err);
     if (local_err) {
@@ -93,64 +86,84 @@ static int raw_read_options(QDict *options, BlockDriverState *bs,
         goto end;
     }
 
-    s->offset = qemu_opt_get_size(opts, "offset", 0);
-    if (s->offset > real_size) {
-        error_setg(errp, "Offset (%" PRIu64 ") cannot be greater than "
-            "size of the containing file (%" PRId64 ")",
-            s->offset, real_size);
-        ret = -EINVAL;
-        goto end;
-    }
+    *offset = qemu_opt_get_size(opts, "offset", 0);
+    *has_size = qemu_opt_find(opts, "size");
+    *size = qemu_opt_get_size(opts, "size", 0);
 
-    if (qemu_opt_find(opts, "size") != NULL) {
-        s->size = qemu_opt_get_size(opts, "size", 0);
-        s->has_size = true;
-    } else {
-        s->has_size = false;
-        s->size = real_size - s->offset;
+    ret = 0;
+end:
+    qemu_opts_del(opts);
+    return ret;
+}
+
+static int raw_apply_options(BlockDriverState *bs, BDRVRawState *s,
+                             uint64_t offset, bool has_size, uint64_t size,
+                             Error **errp)
+{
+    int64_t real_size = 0;
+
+    real_size = bdrv_getlength(bs->file->bs);
+    if (real_size < 0) {
+        error_setg_errno(errp, -real_size, "Could not get image size");
+        return real_size;
     }
 
     /* Check size and offset */
-    if ((real_size - s->offset) < s->size) {
+    if (offset > real_size) {
+        error_setg(errp, "Offset (%" PRIu64 ") cannot be greater than "
+                   "size of the containing file (%" PRId64 ")",
+                   s->offset, real_size);
+        return -EINVAL;
+    }
+
+    if (has_size && (real_size - offset) < size) {
         error_setg(errp, "The sum of offset (%" PRIu64 ") and size "
-            "(%" PRIu64 ") has to be smaller or equal to the "
-            " actual size of the containing file (%" PRId64 ")",
-            s->offset, s->size, real_size);
-        ret = -EINVAL;
-        goto end;
+                   "(%" PRIu64 ") has to be smaller or equal to the "
+                   " actual size of the containing file (%" PRId64 ")",
+                   s->offset, s->size, real_size);
+        return -EINVAL;
     }
 
     /* Make sure size is multiple of BDRV_SECTOR_SIZE to prevent rounding
      * up and leaking out of the specified area. */
-    if (s->has_size && !QEMU_IS_ALIGNED(s->size, BDRV_SECTOR_SIZE)) {
+    if (has_size && !QEMU_IS_ALIGNED(size, BDRV_SECTOR_SIZE)) {
         error_setg(errp, "Specified size is not multiple of %llu",
-            BDRV_SECTOR_SIZE);
-        ret = -EINVAL;
-        goto end;
+                   BDRV_SECTOR_SIZE);
+        return -EINVAL;
     }
 
-    ret = 0;
-
-end:
+    s->offset = offset;
+    s->has_size = has_size;
+    s->size = has_size ? size : real_size - offset;
 
-    qemu_opts_del(opts);
-
-    return ret;
+    return 0;
 }
 
 static int raw_reopen_prepare(BDRVReopenState *reopen_state,
                               BlockReopenQueue *queue, Error **errp)
 {
+    bool has_size;
+    uint64_t offset, size;
+    int ret;
+
     assert(reopen_state != NULL);
     assert(reopen_state->bs != NULL);
 
     reopen_state->opaque = g_new0(BDRVRawState, 1);
 
-    return raw_read_options(
-        reopen_state->options,
-        reopen_state->bs,
-        reopen_state->opaque,
-        errp);
+    ret = raw_read_options(reopen_state->options, &offset, &has_size, &size,
+                           errp);
+    if (ret < 0) {
+        return ret;
+    }
+
+    ret = raw_apply_options(reopen_state->bs, reopen_state->opaque,
+                            offset, has_size, size, errp);
+    if (ret < 0) {
+        return ret;
+    }
+
+    return 0;
 }
 
 static void raw_reopen_commit(BDRVReopenState *state)
@@ -426,8 +439,15 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
                     Error **errp)
 {
     BDRVRawState *s = bs->opaque;
+    bool has_size;
+    uint64_t offset, size;
     int ret;
 
+    ret = raw_read_options(options, &offset, &has_size, &size, errp);
+    if (ret < 0) {
+        return ret;
+    }
+
     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, 0,
                                false, errp);
     if (!bs->file) {
@@ -455,7 +475,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
                 bs->file->bs->filename);
     }
 
-    ret = raw_read_options(options, bs, s, errp);
+    ret = raw_apply_options(bs, s, offset, has_size, size, errp);
     if (ret < 0) {
         return ret;
     }