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Fix some corner cases in TarReader - #74329
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ghost
commented
Aug 22, 2022
Tagging subscribers to this area: @dotnet/area-system-io Issue Details
Contributes to #74316.
|
carlossanlop
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The fix looks good. I just have a question about the test.
| TarEntry? entry = null; | ||
| while (true) | ||
| { | ||
| Exception ex = Record.Exception(() => entry = reader.GetNextEntry()); |
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First time I see Record.Exception being used.
What advantage does it have over simply letting this throw?
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The intent of Record.Exception() followed by Assert.Null() is to be explicit about asserting that 'the method call is not throwing with this fix' (which were throwing without the fix). It also avoids seemingly unused statements to be optimized out by the JIT.
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If you're consuming or asserting something about entry, Name, and Type the jit cannot remove them, and you're implicitly testing that they don't throw.
Eg you can assert that Name is never null, and that if type is Directory then length is zero.
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Eg you could do more or less what the test code did and then you won't need to record the exception explicitly
varms=newMemoryStream();Assert.NotEmpty(entry.Name);Assert.True(Enum.IsDefined(entry.EntryType));Assert.True(Enum.IsDefined(entry.Format));if(entry.EntryType==TarEntryType.Directory)continue;vards=entry.DataStream;if(ds!=null&&ds.Length>0){ds.CopyTo(ms);}danmoseley
commented
Aug 22, 2022
Cc @stephentoub |
carlossanlop
commented
Aug 22, 2022
LGTM. Thanks for fixing this @am11. CI failure was a cancellation due to timeout. @danmoseley I'll prepare the backport manually. |
| ex = Record.Exception(() => entry.Length); | ||
| Assert.Null(ex); | ||
| } |
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Read content into a MemoryStream perhaps, as I did in my test code?
| TarEntry? entry = null; | ||
| while (true) | ||
| { | ||
| Exception ex = Record.Exception(() => entry = reader.GetNextEntry()); |
There was a problem hiding this comment.
If you're consuming or asserting something about entry, Name, and Type the jit cannot remove them, and you're implicitly testing that they don't throw.
Eg you can assert that Name is never null, and that if type is Directory then length is zero.
| TarEntry? entry = null; | ||
| while (true) | ||
| { | ||
| Exception ex = Record.Exception(() => entry = reader.GetNextEntry()); |
There was a problem hiding this comment.
Eg you could do more or less what the test code did and then you won't need to record the exception explicitly
varms=newMemoryStream();Assert.NotEmpty(entry.Name);Assert.True(Enum.IsDefined(entry.EntryType));Assert.True(Enum.IsDefined(entry.Format));if(entry.EntryType==TarEntryType.Directory)continue;vards=entry.DataStream;if(ds!=null&&ds.Length>0){ds.CopyTo(ms);}danmoseley
commented
Aug 22, 2022
@carlossanlop my suggestion about backport is for us to fix the various issues first in main, then bring a single back port PR. It will be less confusing. Also because the code has diverged. |
* Improve performance of Tar library (#74281) * Avoid unnecessary byte[] allocations * Remove unnecessary use of FileStreamOptions * Clean up Dispose{Async} implementations * Clean up unnecessary consts Not a perf thing, just readability. * Remove MemoryStream/Encoding.UTF8.GetBytes allocations, unnecessary async variants, and overhaul GenerateExtendedAttributesDataStream * Avoid string allocations in ReadMagicAttribute * Avoid allocation in WriteAsOctal * Improve handling of octal * Avoid allocation for version string * Removing boxing and char string allocation in GenerateExtendedAttributeName * Fix a couple unnecessary dictionary lookups * Replace Enum.HasFlag usage * Remove allocations from Write{Posix}Name * Replace ArrayPool use with string.Create * Replace more superfluous ArrayPool usage * Remove ArrayPool use from System.IO.Compression.ZipFile * Fix inverted condition * Use generic math to parse octal * Remove allocations from StringReader and string.Split * Remove magic string allocation for Ustar when not V7 * Remove file name and directory name allocation in GenerateExtendedAttributeName * fix tar strings (#74321) * Fix some corner cases in TarReader (#74329) * Fix a few Tar issues post perf improvements (#74338) * Fix a few Tar issues post perf improvements * Update src/libraries/System.Formats.Tar/src/System/Formats/Tar/TarHeader.Write.cs * Skip directory symlink recursion on TarFile archive creation (#74376) * Skip directory symlink recursion on TarFile archive creation * Add symlink verification * Address suggestions by danmoseley Co-authored-by: carlossanlop <carlossanlop@users.noreply.github.com> * SkipBlockAlignmentPadding must be executed for all entries (#74396) * Set modified timestamps on files being extracted from tar archives (#74400) * Add tests for exotic external tar asset archives, fix some more corner case bugs (#74412) * Remove unused _readFirstEntry. Remnant from before we created PaxGlobalExtendedAttributesEntry. * Set the position of the freshly copied data stream to 0, so the first user access of the DataStream property gives them a stream ready to read from the beginning. * Process a PAX actual entry's data block only after the extended attributes are analyzed, in case the size is found as an extended attribute and needs to be overriden. * Add tests to verify the entries of the new external tar assets can be read. Verify their DataStream if available. * Add copyData argument to recent alignment padding tests. * Throw an exception sooner and with a clearer message when a data section is unexpected for the entry type. * Allow trailing nulls and spaces in octal fields. Co-authored-by: @am11 Adeel Mujahid <3840695+am11@users.noreply.github.com> * Throw a clearer exception if the unsupported sparse file entry type is encountered. These entries have additional data that indicates the locations of sparse bytes, which cannot be read with just the size field. So to avoid accidentally offseting the reader, we throw. * Tests. * Rename to TrimLeadingNullsAndSpaces Co-authored-by: carlossanlop <carlossanlop@users.noreply.github.com> * Remove Compression changes, keep changes confined to Tar. * Fix build failure due to missing using in TarHelpers.Windows Co-authored-by: Stephen Toub <stoub@microsoft.com> Co-authored-by: Dan Moseley <danmose@microsoft.com> Co-authored-by: Adeel Mujahid <3840695+am11@users.noreply.github.com> Co-authored-by: carlossanlop <carlossanlop@users.noreply.github.com> Co-authored-by: David Cantú <dacantu@microsoft.com>
Contributes to #74316.