Closed
Bug 1296164
Opened 8 years ago
Closed 8 years ago
Use the [must_use] property in nsIFile.idl
Categories
(Core :: XPCOM, defect)
Core
XPCOM
Tracking
()
RESOLVED
FIXED
People
(Reporter: n.nethercote, Assigned: n.nethercote)
References
Details
Attachments
(3 files)
(deleted),
patch
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froydnj
:
review+
mayhemer
:
feedback-
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Details | Diff | Splinter Review |
(deleted),
patch
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froydnj
:
review+
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Details | Diff | Splinter Review |
(deleted),
patch
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froydnj
:
review+
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Details | Diff | Splinter Review |
We have plenty of missing checks for nsIFile operations. Using [must_use] will find them.
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Assignee | |
Comment 1•8 years ago
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And fix numerous missing checks that this change identifies.
Attachment #8782258 -
Flags: review?(nfroyd)
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Assignee | |
Updated•8 years ago
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Assignee: nobody → n.nethercote
Status: NEW → ASSIGNED
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Assignee | |
Comment 2•8 years ago
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The patch also changes RemoteOpenFileChild::OpenNSPRFileDesc() so that it cannot succeed with a null fd, so that checking just the return value is sufficient.
Attachment #8782283 -
Flags: review?(nfroyd)
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Assignee | |
Comment 3•8 years ago
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These ones don't require any extra checks to be added.
Attachment #8782301 -
Flags: review?(nfroyd)
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Updated•8 years ago
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Attachment #8782258 -
Flags: review?(nfroyd) → review+
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Comment 4•8 years ago
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Comment on attachment 8782283 [details] [diff] [review] (part 2) - Use [must_use] on nsIFile.open{NSPR,ANSI}FileDesc() Review of attachment 8782283 [details] [diff] [review]: ----------------------------------------------------------------- We really should make these sorts of methods result a wrapped PRFileDesc* pointer ala Rust that you have to check prior to unwrapping, rather than futzing around with nsresult.
Attachment #8782283 -
Flags: review?(nfroyd) → review+
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Updated•8 years ago
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Attachment #8782301 -
Flags: review?(nfroyd) → review+
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Assignee | |
Comment 5•8 years ago
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> We really should make these sorts of methods result a wrapped PRFileDesc*
> pointer ala Rust that you have to check prior to unwrapping, rather than
> futzing around with nsresult.
That would be nice... but isn't it prevented by the fact that modifying xptcall is almost impossible?
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Comment 6•8 years ago
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(In reply to Nicholas Nethercote [:njn] from comment #5) > > We really should make these sorts of methods result a wrapped PRFileDesc* > > pointer ala Rust that you have to check prior to unwrapping, rather than > > futzing around with nsresult. > > That would be nice... but isn't it prevented by the fact that modifying > xptcall is almost impossible? This is completely true! Fortunately, these particular methods are [noscript], so we could at least try doing something intelligent with them.
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Assignee | |
Comment 7•8 years ago
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Comment on attachment 8782258 [details] [diff] [review] (part 1) - Use [must_use] on nsIFile.{create,createUnique} Review of attachment 8782258 [details] [diff] [review]: ----------------------------------------------------------------- jduell: the changes to nsDiskCacheDeviceSQL.cpp in this patch caused test failures, so I reverted the |rv| checks and just used |Unused| to explicitly ignore the results of the two Create() calls. Do you understand returning early when either of these calls fails would cause these failures? In the failing test that I looked at, generation==-1 was false in the cases when the Create() calls failed, and the file->AppendNative(nsDependentCString(leaf)) call in the |else| branch succeeded.
Attachment #8782258 -
Flags: feedback?(jduell.mcbugs)
Comment 8•8 years ago
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(In reply to Nathan Froyd [:froydnj] from comment #6) > (In reply to Nicholas Nethercote [:njn] from comment #5) > > > We really should make these sorts of methods result a wrapped PRFileDesc* > > > pointer ala Rust that you have to check prior to unwrapping, rather than > > > futzing around with nsresult. > > > > That would be nice... but isn't it prevented by the fact that modifying > > xptcall is almost impossible? > > This is completely true! Fortunately, these particular methods are > [noscript], so we could at least try doing something intelligent with them. we have noscript methods that return already_AddRefed<> so Maybe<PRFileDesc> should work too. iirc the trick is |native MaybeFileDesc(Maybe<PRFileDesc>);|
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Assignee | |
Comment 9•8 years ago
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> jduell: the changes to nsDiskCacheDeviceSQL.cpp in this patch caused test
> failures, so I reverted the |rv| checks and just used |Unused| to explicitly
> ignore the results of the two Create() calls. Do you understand returning
> early when either of these calls fails would cause these failures?
Ah, the failing rv values were 80520008, which is NS_ERROR_FILE_ALREADY_EXISTS.
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Assignee | |
Comment 10•8 years ago
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https://hg.mozilla.org/integration/mozilla-inbound/rev/51410d553f6f0c1c260f3e63012b024484dfe67a Bug 1296164 (part 1) - Use [must_use] on nsIFile.{create,createUnique}. r=froydnj. https://hg.mozilla.org/integration/mozilla-inbound/rev/193c7e5b2ee4355f70f1d1bf10b953bd5cbdd8c8 Bug 1296164 (part 2) - Use [must_use] on nsIFile.open{NSPR,ANSI}FileDesc(). r=froydnj. https://hg.mozilla.org/integration/mozilla-inbound/rev/ed27be6470e5690889079fc0bf5c0ed9626f9eb3 Bug 1296164 (part 3) - Use [must_use] on more nsIFile things. r=froydnj.
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Assignee | |
Comment 11•8 years ago
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I'm marking this leave-open because there is more to be done.
Keywords: leave-open
Comment 12•8 years ago
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Comment on attachment 8782258 [details] [diff] [review] (part 1) - Use [must_use] on nsIFile.{create,createUnique} Review of attachment 8782258 [details] [diff] [review]: ----------------------------------------------------------------- Honza is our expert on the appcache, so he's the right person for the nsDiskCacheDeviceSQL.cpp question (Honza, see comment 7)
Attachment #8782258 -
Flags: feedback?(jduell.mcbugs) → feedback?(honzab.moz)
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Comment 13•8 years ago
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(In reply to Nicholas Nethercote [:njn] from comment #7) > Comment on attachment 8782258 [details] [diff] [review] > (part 1) - Use [must_use] on nsIFile.{create,createUnique} > > Review of attachment 8782258 [details] [diff] [review]: > ----------------------------------------------------------------- > > jduell: the changes to nsDiskCacheDeviceSQL.cpp in this patch caused test > failures, so I reverted the |rv| checks and just used |Unused| to explicitly > ignore the results of the two Create() calls. Do you understand returning > early when either of these calls fails would cause these failures? > > In the failing test that I looked at, generation==-1 was false in the cases > when the Create() calls failed, and the > file->AppendNative(nsDependentCString(leaf)) call in the |else| branch > succeeded. This is an "ensure directory exists" code. It probably already exists. I think you can freely ignore the failures here, if there is anything wrong with the storage I believe we fail later when creating the leaf cache file gracefully.
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Comment 14•8 years ago
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Comment on attachment 8782258 [details] [diff] [review] (part 1) - Use [must_use] on nsIFile.{create,createUnique} Review of attachment 8782258 [details] [diff] [review]: ----------------------------------------------------------------- ::: netwerk/cache/nsDiskCacheDeviceSQL.cpp @@ +384,5 @@ > const nsCString *fullKey, > int generation) > { > + nsresult rv; > + I like this! ;) @@ +407,5 @@ > > file->AppendNative(nsPrintfCString("%X", dir1)); > + rv = file->Create(nsIFile::DIRECTORY_TYPE, 00700); > + if (NS_FAILED(rv)) > + return nullptr; ideally we should do something like "if not exists -> Create()" but I don't think there is a need for additional IO. this code is deprecated, hence, do minimal changes to it.
Attachment #8782258 -
Flags: feedback?(honzab.moz) → feedback-
Comment 15•8 years ago
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bugherder |
https://hg.mozilla.org/mozilla-central/rev/51410d553f6f https://hg.mozilla.org/mozilla-central/rev/193c7e5b2ee4 https://hg.mozilla.org/mozilla-central/rev/ed27be6470e5
Comment 16•8 years ago
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Why do you ignore the return value here? https://hg.mozilla.org/mozilla-central/rev/ed27be6470e5#l1.29 Further down persistentDescriptor is passed into AddDownloadToDB(). Never fails under the given circumstances? GetPersistentDescriptor() doesn't seem to fail in general, but there are call sites in M-C which check the return value. Windows: https://dxr.mozilla.org/comm-central/rev/24763f58772d45279a935790f732d80851924b46/mozilla/xpcom/io/nsLocalFileWin.cpp#3186 Does not fail. Linux + Mac: https://dxr.mozilla.org/comm-central/rev/24763f58772d45279a935790f732d80851924b46/mozilla/xpcom/io/nsLocalFileUnix.cpp#1885 https://dxr.mozilla.org/comm-central/rev/24763f58772d45279a935790f732d80851924b46/mozilla/xpcom/io/nsLocalFileUnix.cpp#600 Does not fail.
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Assignee | |
Comment 17•8 years ago
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(In reply to Jorg K (GMT+2, PTO during summer) from comment #16) > Why do you ignore the return value here? > https://hg.mozilla.org/mozilla-central/rev/ed27be6470e5#l1.29 > Further down persistentDescriptor is passed into AddDownloadToDB(). > Never fails under the given circumstances? There was already a cast to void. That's not enough to satisfy GCC when a MOZ_MUST_USE annotation is present, so I changed it to |Unused <<|. I assumed that the existing cast to void was legitimate. > GetPersistentDescriptor() doesn't seem to fail in general, but there are > call sites in M-C which check the return value. > > Windows: > https://dxr.mozilla.org/comm-central/rev/ > 24763f58772d45279a935790f732d80851924b46/mozilla/xpcom/io/nsLocalFileWin. > cpp#3186 > Does not fail. > > Linux + Mac: > https://dxr.mozilla.org/comm-central/rev/ > 24763f58772d45279a935790f732d80851924b46/mozilla/xpcom/io/nsLocalFileUnix. > cpp#1885 > https://dxr.mozilla.org/comm-central/rev/ > 24763f58772d45279a935790f732d80851924b46/mozilla/xpcom/io/nsLocalFileUnix. > cpp#600 > Does not fail. The RemoteOpenFileChild::GetPersistentDescriptor() implementation can fail. I don't know how often that implementation is used, so I erred on the side of conservatism, i.e. over-checking. If you know this is wrong, please file a follow-up bug!
Blocks: 1310586
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Description
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