When I originally implemented bug 1458161, this is how it was done, but
it was suggested to use a configure-time check. This turned out to not
be great, because the rust compiler changes regularly, and we don't run
the configure tests when the version changes. When people upgraded their
rust compiler to 1.27, the code subsequently failed to build because the
features were still set for the previous version they had installed.
Bug 1458161 added a rust OOM handler based on an unstable API that was
removed in 1.27, replaced with something that didn't allow to get the
failed allocation size.
Latest 1.28 nightly (2018-06-13) has
https://github.com/rust-lang/rust/pull/50880,
https://github.com/rust-lang/rust/pull/51264 and
https://github.com/rust-lang/rust/pull/51241 merged, which allow to
hook the OOM handler and get the failed allocation size again.
Because this is still an unstable API, we explicitly depend on strict
versions of rustc. We also explicitly error out if automation builds
end up using a rustc version that doesn't allow us to get the allocation
size for rust OOM, because we don't want that to happen without knowing.
Update mp4parse-rust to 0c8e1d91464aaa63b82ebf076b63cda1df4230d1, which adds
uuid parsing support and exports the mp4parse_fallible feature from
mp4parse_capi.
Update gkrust to pass MOZ_MEMORY as a feature, and use that to conditionally
enable mp4parse_fallible/FallibleVec.
MozReview-Commit-ID: 2HDYbL2CGgJ
Update mp4parse-rust to 0c8e1d91464aaa63b82ebf076b63cda1df4230d1, which adds
uuid parsing support and exports the mp4parse_fallible feature from
mp4parse_capi.
Update gkrust to pass MOZ_MEMORY as a feature, and use that to conditionally
enable mp4parse_fallible/FallibleVec.
MozReview-Commit-ID: 2HDYbL2CGgJ
OOM rust crashes are currently not identified as such in crash reports
because rust libstd handles the OOMs and panics itself.
There are unstable ways to hook into this, which unfortunately are under
active changes in rust 1.27, but we're currently on 1.24 and 1.27 is not
released yet. The APIs didn't change between 1.24 and 1.26, so it's
fine-ish to use them as long as we limit their use to those versions.
As long as the Firefox versions we ship (as opposed to downstream) use
the "right" version of rust, we're good to go.
The APIs are in their phase of stabilization, so there shouldn't be too
many variants of the code to support.
This patch rewrites the rust-url-capi crate as the mozurl crate, which
provides a threadsafe MozURL object which is compatible with the
previous MozURL class.
Creating a MozURL this way performs a single allocation, which contains
only a rust-url Url object and an atomic refcnt, however it is fully
compatible with the C++ RefPtr type.
This patch also exposes methods for accessing dependent substrings of
the serialized spec, meaning that string copies can be avoided in many
situations when inspecting attributes of the MozURL.
Remove the syn dependency from gkrust-shared, which was added in bug 1373878
as a workaround for this Cargo bug:
https://github.com/rust-lang/cargo/issues/3923
MozReview-Commit-ID: L34J0davEYd
The prefs parser has two significant problems.
- It doesn't separate tokenizing from parsing.
- It is implemented as a loop around a big switch on a "current state"
variable.
As a result, it is hard to understand and modify, slower than it could be, and
in obscure cases (involving comments and whitespace) it fails to parse what
should be valid input.
This patch replaces it with a recursive descent parser (albeit one without any
recursion!) that has separate tokenization. The new parser is easier to
understand and modify, more correct, and has better error messages. It doesn't
do error recovery, but that would be much easier to add than in the old parser.
The new parser also runs about 1.9x faster than the existing parser. (As
measured by parsing greprefs.js's contents from memory 1000 times in
succession, omitting the prefs hash table construction. If the table
construction is included, it's about 1.6x faster.)
The new parser is slightly stricter than the old parser in a few ways.
- Disconcertingly, the old parser allowed arbitrary junk between prefs
(including at the start and end of the prefs file) so long as that junk
didn't include any of the following chars: '/', '#', 'u', 's', 'p'. I.e.
lines like these:
!foo@bar&pref("prefname", true);
ticky_pref("prefname", true); // missing 's' at start
User_pref("prefname", true); // should be 'u' at start
would all be treated the same as this:
pref("prefname", true);
The new parser disallows such junk because it isn't necessary and seems like
an unintentional botch by the old parser.
- The old parser allowed character 0x1a (SUB) between tokens and treated it
like '\n'.
The new parser does not allow this character. SUB was used to indicate
end-of-file (*not* end-of-line) in some old operating systems such as MS-DOS,
but this doesn't seem necessary today.
- The old parser tolerated (with a warning) invalid escape sequences within
string literals -- such as "\q" (not a valid escape) and "\x1" and "\u12"
(both of which have insufficient hex digits) -- accepting them literally.
The new parser does not tolerate invalid escape sequences because it doesn't
seem necessary and would complicate things.
- The old parser tolerated character 0x00 (NUL) within string literals; this is
dangerous because C++ code that manipulates string values with embedded NULs
will almost certainly consider those chars as end-of-string markers.
The new parser treats NUL chars as end-of-file, to avoid this danger and
because it facilitates a significant optimization (described within the
code).
- The old parser allowed integer literals to overflow, silently wrapping them.
The new parser treats integer overflow as a parse error. This seems better,
and it caught existing overflows of places.database.lastMaintenance, in
testing/profiles/prefs_general.js (bug 1424030) and
testing/talos/talos/config.py (bug 1434813).
The first of these changes meant that a couple of existing prefs with ";;" at
the end had to be changed (done in the preceding patch).
The minor increase in strictness shouldn't be a problem for default pref files
such as greprefs.js within the application (which we can modify), nor for
app-written prefs files such as prefs.js. It could affect user-written prefs
files such as user.js; the experience above suggests that integer overflow and
";;" are the most likely problems in practice. In my opinion, the risk here is
acceptable.
The new parser also does a better job of tracking line numbers because it (a)
treats "\r\n" sequences as a single end-of-line marker, and (a) pays attention
to end-of-line sequences within string literals.
Finally, the patch adds thorough tests of both valid and invalid syntax.
MozReview-Commit-ID: JD3beOQl4AJ
The prefs parser has two significant problems.
- It doesn't separate tokenizing from parsing.
- It is implemented as a loop around a big switch on a "current state"
variable.
As a result, it is hard to understand and modify, slower than it could be, and
in obscure cases (involving comments and whitespace) it fails to parse what
should be valid input.
This patch replaces it with a recursive descent parser (albeit one without any
recursion!) that has separate tokenization. The new parser is easier to
understand and modify, more correct, and has better error messages. It doesn't
do error recovery, but that would be much easier to add than in the old parser.
The new parser also runs about 1.9x faster than the existing parser. (As
measured by parsing greprefs.js's contents from memory 1000 times in
succession, omitting the prefs hash table construction. If the table
construction is included, it's about 1.6x faster.)
The new parser is slightly stricter than the old parser in a few ways.
- Disconcertingly, the old parser allowed arbitrary junk between prefs
(including at the start and end of the prefs file) so long as that junk
didn't include any of the following chars: '/', '#', 'u', 's', 'p'. I.e.
lines like these:
!foo@bar&pref("prefname", true);
ticky_pref("prefname", true); // missing 's' at start
User_pref("prefname", true); // should be 'u' at start
would all be treated the same as this:
pref("prefname", true);
The new parser disallows such junk because it isn't necessary and seems like
an unintentional botch by the old parser.
- The old parser allowed character 0x1a (SUB) between tokens and treated it
like '\n'.
The new parser does not allow this character. SUB was used to indicate
end-of-file (*not* end-of-line) in some old operating systems such as MS-DOS,
but this doesn't seem necessary today.
- The old parser tolerated (with a warning) invalid escape sequences within
string literals -- such as "\q" (not a valid escape) and "\x1" and "\u12"
(both of which have insufficient hex digits) -- accepting them literally.
The new parser does not tolerate invalid escape sequences because it doesn't
seem necessary and would complicate things.
- The old parser tolerated character 0x00 (NUL) within string literals; this is
dangerous because C++ code that manipulates string values with embedded NULs
will almost certainly consider those chars as end-of-string markers.
The new parser treats NUL chars as end-of-file, to avoid this danger and
because it facilitates a significant optimization (described within the
code).
- The old parser allowed integer literals to overflow, silently wrapping them.
The new parser treats integer overflow as a parse error. This seems better,
and it caught an existing overflow in testing/profiles/prefs_general.js, for
places.database.lastMaintenance (see bug 1424030).
The first of these changes meant that a couple of existing prefs with ";;" at
the end had to be changed (done in the preceding patch).
The minor increase in strictness shouldn't be a problem for default pref files
such as greprefs.js within the application (which we can modify), nor for
app-written prefs files such as prefs.js. It could affect user-written prefs
files such as user.js; the experience above suggests that ";;" is the most
likely problem in practice. In my opinion, the risk here is acceptable.
The new parser also does a better job of tracking line numbers because it (a)
treats "\r\n" sequences as a single end-of-line marker, and (a) pays attention
to end-of-line sequences within string literals.
Finally, the patch adds thorough tests of both valid and invalid syntax.
MozReview-Commit-ID: 8EYWH7KxGG
* * *
[mq]: win-fix
MozReview-Commit-ID: 91Bxjfghqfw
The easy part of this patch is the addition of the RustTest itself.
The more difficult to understand part of the patch is the changes to all
of our Rust build configuration. We do this due to a bug in cargo:
https://github.com/rust-lang/cargo/issues/3923
where features on dependent crates are not correctly taken into account
when determining whether cached artifacts on disk are valid and whether
they should be evicted from the disk cache. The practical upshot of
this behavior is that, say, running gtests during normal development
when files in libxul are modified will:
* rebuild some Rust dependencies for libxul;
* link libxul;
* rebuild those same Rust dependencies *again* for libxul-gtest, since
we have different features active and therefore the old artifacts look
to be out of date;
* link libxul-gtest.
Needless to say, this is highly annoying and counterproductive behavior.
The "fix" is to ensure that the gkrust-shared crate explicitly depends
on crates and assigns features to them such that the feature sets do not
change between normal builds and testing builds. This is admittedly
fragile, but it is not the first time this has come up, and is probably
not the last.
Crash reporter installs a special Rust panic hook to grab the panic reason.
However, we still want to call the default hook as well, so that we still print
the reason and backtrace to the console.
MozReview-Commit-ID: JlCamBPb51X
Servo needs to know whether C++ code is compiled with MOZ_DEBUG, and
passing along an explicit feature is a better way to determine that
information than relying on cfg(debug_assertions).
MozReview-Commit-ID: B3XCskDQ56p
For testing purposes it will be useful to be able to trigger crashes in Rust
code. Being able to trigger a panic seems like a good place to start. This
will make it easier to validate improvements in crash reporting.
MozReview-Commit-ID: Bh5rBieLLWW
For testing purposes it will be useful to be able to trigger crashes in Rust
code. Being able to trigger a panic seems like a good place to start. This
will make it easier to validate improvements in crash reporting.
MozReview-Commit-ID: Bh5rBieLLWW
