vmdk: Use g_random_int to generate CID

This replaces two "time(NULL)" invocations with "g_random_int()".
According to VMDK spec, CID "is a random 32‐bit value updated the first
time the content of the virtual disk is modified after the virtual disk
is opened". Using "seconds since epoch" is just a "lame way" to generate
it, and not completely safe because of the low precision.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Don Koch <dkoch@verizon.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1417649314-13704-2-git-send-email-famz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
vmdk: Fix comment to match code of extent lines

commit 04d542c8b (vmdk: support vmfs files) added support of VMFS extent
type but the comment above the changed code is left out. Update the
comment so they are consistent.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Don Koch <dkoch@verizon.com>
Message-id: 1417649314-13704-3-git-send-email-famz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
vmdk: Clean up descriptor file reading

Zeroing a buffer that will be filled right after is not necessary, and
allocating a power of two + 1 is naughty.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Don Koch <dkoch@verizon.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1417649314-13704-4-git-send-email-famz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
vmdk: Check descriptor file length when reading it

Since a too small file cannot be a valid VMDK image, and also since the
buffer's first 4 bytes will be unconditionally examined by
vmdk_open_sparse, let's error out the small file case to be clear.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Don Koch <dkoch@verizon.com>
Message-id: 1417649314-13704-5-git-send-email-famz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
vmdk: Remove unnecessary initialization

It will be assigned to the return value of vmdk_read_desc.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Don Koch <dkoch@verizon.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1417649314-13704-6-git-send-email-famz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
vmdk: Set errp on failures in vmdk_open_vmdk4

Reported-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Don Koch <dkoch@verizon.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1417649314-13704-7-git-send-email-famz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>