The Reader and Writer have hard-coded constants regarding the
offsets and lengths of certain fields in the tar format sprinkled
all over. This makes it harder to verify that the offsets are
correct since a reviewer would need to search for them throughout
the code. Instead, all information about the layout of header
fields should be centralized in one single file. This has the
advantage of being both centralized, and also acting as a form
of documentation about the header struct format.
This method was chosen over using "encoding/binary" since that
method would cause an allocation of a header struct every time
binary.Read was called. This method causes zero allocations and
its logic is no longer than if structs were declared.
Updates #12594
Change-Id: Ic7a0565d2a2cd95d955547ace3b6dea2b57fab34
Reviewed-on: https://go-review.googlesource.com/14669
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>
Motivation:
* Previous implementation silently failed when an integer overflow
occurred. Now, we report an ErrFieldTooLong.
* Previous implementation did not encode in two's complement format and was
unable to encode negative numbers.
The relevant GNU specification says:
<<<
GNU format uses two's-complement base-256 notation to store values
that do not fit into standard ustar range.
>>>
Fixes#12436
Change-Id: I09c20602eabf8ae3a7e0db35b79440a64bfaf807
Reviewed-on: https://go-review.googlesource.com/17425
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Motivations:
* Use of strconv.ParseInt does not properly treat integers as 64bit,
preventing this function from working properly on 32bit machines.
* Use of io.ReadFull does not properly detect truncated streams
when the file suddenly ends on a block boundary.
* The function blindly trusts user input for numEntries and allocates
memory accordingly.
* The function does not validate that numEntries is not negative,
allowing a malicious sparse file to cause a panic during make.
In general, this function was overly complicated for what it was
accomplishing and it was hard to reason that it was free from
bounds errors. Instead, it has been rewritten and relies on
bytes.Buffer.ReadString to do the main work. So long as invariants
about the number of '\n' in the buffer are maintained, it is much
easier to see why this approach is correct.
Change-Id: Ibb12c4126c26e0ea460ea063cd17af68e3cf609e
Reviewed-on: https://go-review.googlesource.com/15174
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Motivation:
* Reader.skipUnread never reports io.ErrUnexpectedEOF. This is strange
given that io.ErrUnexpectedEOF is given through Reader.Read if the
user manually reads the file.
* Reader.skipUnread fails to detect truncated files since io.Seeker
is lazy about reporting errors. Thus, the behavior of Reader differs
whether the input io.Reader also satisfies io.Seeker or not.
To solve this, we seek to one before the end of the data section and
always rely on at least one call to io.CopyN. If the tr.r satisfies
io.Seeker, this is guarunteed to never read more than blockSize.
Fixes#12557
Change-Id: I0ddddfc6bed0d74465cb7e7a02b26f1de7a7a279
Reviewed-on: https://go-review.googlesource.com/15175
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Convert splitUSTARPath to return a bool rather than an error since
the caller never ever uses the error other than to check if it is
nil. Thus, we can remove errNameTooLong as well.
Also, fold the checking of the length <= fileNameSize and whether
the string is ASCII into the split function itself.
Lastly, remove logic to set the MAGIC since that's already done on
L200. Thus, setting the magic is redundant.
There is no overall logic change.
Updates #12638
Change-Id: I26b6992578199abad723c2a2af7f4fc078af9c17
Reviewed-on: https://go-review.googlesource.com/14723
Reviewed-by: David Symonds <dsymonds@golang.org>
Run-TryBot: David Symonds <dsymonds@golang.org>
The issue was identified while
working with round trip FileInfo of the headers of hardlinks. Also,
additional test cases for hard link handling.
(review carried over from http://golang.org/cl/165860043)
Fixes#9027
Change-Id: I9e3a724c8de72eb1b0fbe0751a7b488894911b76
Reviewed-on: https://go-review.googlesource.com/6790
Reviewed-by: Russ Cox <rsc@golang.org>
Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>
Write should return ErrWriteAfterClose instead
of ErrWriteTooLong when called after Close.
Change-Id: If5ec4ef924e4c56489e0d426976f7e5fad79be9b
Reviewed-on: https://go-review.googlesource.com/9259
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>
