Summary: Add `kHasWeakSymbols` to `folly/Portability.h` so that downstream call-sites may detect availability of weak symbols at compile time in normal C++.

Reviewed By: luciang

Differential Revision: D25788659

fbshipit-source-id: 66768486317986396440099adecfc8dc8e553c7c

Summary:
The certificate identity verifier is meant to verify the end entity certificate
in a certificate chain. It assumes that OpenSSL has already validated that
the end entity has a valid signature by an issuer.

The test that I am removing is asserting buggy behavior in OpenSSL prior to
version OpenSSL 1.1.1i. The test scenario sets up a client *without a certificate
store* connecting to a server. When the client attempts to validate this
certificate chain, it will receive two errors:

1. Unable to find issuer locally. Because the test server's certificate is signed
   by an issuer that is not present in the client's (empty) certificate store,
   while trying to determine the issuer during chain building, OpenSSL fails as
   expected. Because the test scenario *intentionally* overrides this error by
   returning `true` in `handshakeVer`, OpenSSL continues its certificate
   validation procedure.

2. Unable to verify leaf signature. In order to validate the signature for a
   certificate, one needs to know the public key of the issuer. However, the
   client does not know about the issuer. Control flow would normally not reach
   here, but the client chose to continue the validation process without knowing
   the issuer in step 1. The test scenario forcefully returns "true" here, telling
   OpenSSL to continue.

Prior to OpenSSL 1.1.1i (specifically commit [2e06150e](https://github.com/openssl/openssl/commit/2e06150e3928daa06d5ff70c32bffad8088ebe58)),
OpenSSL would stop the verification procedure here. It would never signal the
completion of the verification procedure (by sending `preverify_ok=1`).

The test was asserting that this was expected. This meant that the test was
asserting behavior on an incorrect implementation. With OpenSSL 1.1.1i, if
all previous `handshakeVer` callbacks say that the certificate is fine, then
OpenSSL will perform the final call with `preverify_ok=1`, which will cause the
CertificateIdentityVerifier to be invoked.

Differential Revision: D25775428

fbshipit-source-id: 8a5f388ce2eb9a8d5667fd4e840b6b223e618d43

Summary:
Some tests were relying on internal OpenSSL behavior that changed in OpenSSL
1.1.1i.

OpenSSL commit [2e06150e](https://github.com/openssl/openssl/commit/2e06150e3928daa06d5ff70c32bffad8088ebe58)
causes additional `handshakeVer` callback invocations. If an UNABLE_TO_VERIFY_LEAF_SIGNATURE handshakeVer
callback overrides the result to *true*, OpenSSL will now continue to perform certificate
verifications **as if the overriden cert was the properly found root**. This means:

* It is subject to certificate expiration checks, and,
* A final `handshakeVer` callback is invoked with `preverifyOk=1` when it passes the expiration checks.

Several of our tests that relied on `handshakeVer` only being called *once* broke. Since the tests
are testing a different, higher level aspect of verification (i.e. it is not actually trying to
test how many times `handshakeVer` is being called), I've relaxed some of the expectations to allow
for multiple invocations.

CertificateVerifier semantics were also affected. Because there is a final
successful `handshakeVer` callback that is issued, it is not just sufficient
to check for depth and preverifyOk before invoking the CertificateVerifier.

Reviewed By: pixelb

Differential Revision: D25775429

fbshipit-source-id: 98d35249a623307fb1de366c498b1dbae4fabf82

Differential Revision: D25759768

fbshipit-source-id: c0d38b25ab74bfce82c3d5e1339bd4ceef98af14

folly: symbolizer: check if findSubProgramDieForAddress found the DW_TAG_subprogram for address & terminate DFS early

Summary:
It's legal that a CU has `DW_AT_ranges` listing all addresses, but not have a `DW_TAG_subprogram` child DIE for some of those addresses.

Check for `findSubProgramDieForAddress` success before reading potentially empty `subprogram` attributes in `eachParameterName`.

This is a bugfix. If `DW_TAG_subprogram` is missing, we read attributes for using offsets in the uninitialized DIE `subprogram`.

Initialize all struct members to avoid wasting time debugging uninitialized memory access (had fun with uninitialized `subprogram.abbr.tag` magically picking up `DW_TAG_subprogram` or garbage on the stack from previous calls).

 ---

Terminate `findSubProgramDieForAddress` DFS on match.

Before:
- when the DW_TAG_subprogram DIE was found we stopped scanning its direct siblings (the above "return false" when `pcMatch` or `rangeMatch` are true).
- but when we returned from recursion in the parent DIE we discarded the fact that we found the DW_TAG_subprogram and continued the DFS scan through all remaining DIEs.

After:
- after finding the DW_TAG_subprogram that owns that address the scan stops.

As reference when using `-fno-debug-types-section` type info is part of `.debug_info`.

```
namespace folly::symbolizer::test {
void function_A();
class SomeClass { void some_member_function() {} };
void function_B();
} // folly::symbolizer::test
```

```
0x0000004c:   DW_TAG_namespace [2] *
                DW_AT_name [DW_FORM_strp]       ( "folly")

0x00000051:     DW_TAG_namespace [2] *
                  DW_AT_name [DW_FORM_strp]     ( "symbolizer")

0x00000056:       DW_TAG_namespace [2] *
                    DW_AT_name [DW_FORM_strp]   ( "test")

0x0000012e:         DW_TAG_subprogram [7] *
                      DW_AT_name [DW_FORM_strp] ( "function_A")

0x0000022d:         DW_TAG_class_type [14] *
                      DW_AT_name [DW_FORM_strp] ( "SomeClass")

0x00000243:           DW_TAG_subprogram [16] *
                        DW_AT_name [DW_FORM_strp]       ( "some_member_function")

0x000002ed:         DW_TAG_subprogram [9] *
                      DW_AT_name [DW_FORM_strp] ( "function_B")
```

Before:
- if `address` corresponds to code inside `SomeClass::some_member_function` we stopped iterating over `SomeClass::some_member_function`'s sibling DIEs, and returned.
- but we still continued scanning over `SomeClass`'s sibling DIEs and all their children recursively (DFS), and then `SomeClass`'s parents siblings etc until reaching the end of the CU

After:
- we stop DFS on match

FWIW: trees are somewhat flatter when using `-fdebug-types-section`: member functions are extracted from their classes, but they're still part of namespace subtrees so the code unnecessarily explored siblings of the innermost namespace.

Differential Revision: D25799618

fbshipit-source-id: 9a0267e12a7d496ad00263bf30a12dc548764288

Summary:
This code implicitly casts a `long` to `double` but a `double`
can not accurately represent an integer above `2^53` as
the mantissa only stores that many digits. At `2^53 + 1`
`double`s increment by `2`. Thus this cast is lossy. Though,
casting a single value `LONG_MAX` to a `double` is and
being off by one doesn't cause any harm here.

Reviewed By: ispeters

Differential Revision: D25654006

fbshipit-source-id: 3d84092f1786d7879dd48d73af8edbbc80bb3585

folly::symbolizer: drop templated FrameArray from test functions and move test functions to separate compilation unit with minimal dependencies

Summary:
Eliminate `#include` dependencies of `SymbolizerTestUtils.cpp` so that the `.o` file with interesting debug info is tiny and easily inspectable.
- Instead of calling test functions that need to be inlined from the `SymbolizerTest.o` use `call_` trampolines so that the inlined debug info is generated in the minimal/tiny `SymbolizerTestUtils.o`.

 ---

Remove the frames template argument so that:
- removed dependencies from the SymbolizerTestUtils to minimize generated debug info (no longer need to include headers about FrameArray).
- all functions used in tests can be made regular functions
- all functions who's debug info is interesting to debug can be easily emitted in a single object file `SymbolizerTestUtils.o`

Reduce some of the copy-pasta that made test noisy by grouping together function name, file and lineno.

 ---

Test for either fullName/shortName (`DW_AT_linkage_name`/`DW_AT_name`)
- fullName: demangled function name with namespace, qualifiers, argument types, etc. and
- shortName: simple function name to support both cases when either both `DW_AT_linkage_name` and `DW_AT_name` or a single one of them is emitted.
- When `DW_AT_linkage_name` (full mangled name) and `DW_AT_name` (just the function name) match, DWARF emitters omit `DW_AT_linkage_name` (to save space). With `-fsplit-dwarf-inlining` only `DW_AT_name` is emitted in `.debug_info` and the `DW_AT_linkage_name` is emitted in the `.debug_info.dwo` sections.

Differential Revision: D25712808

fbshipit-source-id: 88d2ac22564e3d607fb3864d37e49892a5eaf002

Reviewed By: yfeldblum

Differential Revision: D25527140

fbshipit-source-id: 2a2721ca4418e1a4c57f621f41716e5c8f27869c

Summary:
Small change - adding  logs to connect error/success and eliminating the unnecessary ones.

(Note: this ignores all push blocking failures!)

Reviewed By: yfeldblum

Differential Revision: D25481273

fbshipit-source-id: 437942803bc895bba2eaa36e5eaf104503012d12

Summary:
Adding priorities to `ThreadManagerExecutorAdapter`. The API allows to pass single executor that would be used for all priorities (preserved behavior) but also allows to add custom executors per-priority. In this case, if no executor has been provided for priority, we will spin up default thread manager implementation (which supports upstream queues).

We soon will add upstream queues on top of user-provided executors as well.

Reviewed By: prshreshtha

Differential Revision: D25137444

fbshipit-source-id: db0740a705dd3cca69916f3d1b8c4e32c011aa43

Summary:
Allow callbacks to be attached to a SettingCore (via SettingWrapper),
with lifetime managed by a guard object which automatically unregisters
the callback at destruction. This provides an API for clients to react
to changes in settings without polling.

Reviewed By: yfeldblum

Differential Revision: D25592427

fbshipit-source-id: a11a98ed651ef56a0fc86f5f5e4ed235f2289746

Summary:
the n argument in XLOG_EVERY_N is not captured by it's lambda, so
expressions using local variables can not be passed as n. EdenFS has
a use case where we would like to use local variables here. We want to use a
dynamic config value for n, so that we can easily adjust how often we log
see: D25505654.

It seems like it should be ok to capture the n here, but I am by no means a
macro expert, so please let me know if there is a tricky cpp thing here lurking
that makes capturing n bad.

Reviewed By: simpkins

Differential Revision: D25551033

fbshipit-source-id: e82fa465823d3d2ee2ac26924cc4a93b7b7242dd

Summary: Fix OSS build - move struct/enums into their own namespace

Reviewed By: danobi, lnicco

Differential Revision: D25769992

fbshipit-source-id: 1e337820edbd986bdd47099cf8af942698e6fc75

Summary:
Pull Request resolved: https://github.com/facebook/folly/pull/1512

Hazptr library creates its own CPU executor which name interfere with default executor name. We want to avoid this.
Also insure that the thread is permanent, otherwise folly runtime may destroy and recreate it periodically.

Reviewed By: magedm

Differential Revision: D25708252

fbshipit-source-id: 2b41ad4fa28d2ba9c9bd69bc5d4a02b933d79e66

Summary: Increase the timeout value to avoid false positives

Reviewed By: kevin-vigor

Differential Revision: D25757480

fbshipit-source-id: b3c2498a2573af323a2291f0d0aa875f897bea38

Summary: Initialize the context first to skip the tests if the backend is not available

Reviewed By: kevin-vigor

Differential Revision: D25742461

fbshipit-source-id: 4cbe9545d358dd2bb3ca9297d8b46e80c54f53f7

Summary: Skip the tests if the backend is not avaialable

Reviewed By: kevin-vigor

Differential Revision: D25724617

fbshipit-source-id: 0981f69aca02d7d2b1576df4d82e4ed1167d2935

Summary: Try to allocate all the EventBase instances first before running the test

Reviewed By: kevin-vigor

Differential Revision: D25720889

fbshipit-source-id: 93c837e68771f1ef44e80865bec260813158c6b3

Summary: Let `AsyncPipe::create` return the correct pipe type, namely, the type on which it is a member rather than a different instantiation of the template.

Reviewed By: iahs

Differential Revision: D25717180

fbshipit-source-id: 94a5a657e83b5d4cac866277ec5925c0b5b0af28

Summary: Using std::optional requires including it first.

Reviewed By: yfeldblum

Differential Revision: D25704383

fbshipit-source-id: 755dfd4a6dec9695cb0ed156166d13b550fd8b40

Summary:
Adds a new awaitable that extracs the current async stack-trace as a vector
of program counters from within the current coroutine.

Usage:
```
std::vector<std::uintptr_t> programCounters =
  co_await folly::coro::co_current_async_stack_trace;
```

Reviewed By: andriigrynenko

Differential Revision: D21130683

fbshipit-source-id: bf67a9969f73bdb8b91b4cc2858883b8e87762e2

Summary: Defined new callback - ReadAncillaryDataCallback, which enables getting ancillary data when receive a message using recvmsg API.

Reviewed By: cgrushko

Differential Revision: D24246707

fbshipit-source-id: 3363b5fafe8d370cf5560afe00476fc8ea723e7a

Summary: Also re-order the test slightly to catch this.

Reviewed By: yfeldblum

Differential Revision: D25704580

fbshipit-source-id: 1421daed11a0d41e1b99d573b38fc8fc70381486

Summary: All changes were automated

Reviewed By: Orvid

Differential Revision: D25507505

fbshipit-source-id: 4a1ae7578876975e20fd8eba194b9f8ed43d3530

Summary: All changes were automated

Reviewed By: Orvid

Differential Revision: D25507540

fbshipit-source-id: 71279e19ddad29622c14729d73f5d0d45f0ba410

Summary: All changes were automated

Reviewed By: Orvid

Differential Revision: D25507581

fbshipit-source-id: 5c936f1f81c5c754d3b64fb17b7dab253a178a39

Summary:
Fix gso typo

(Note: this ignores all push blocking failures!)

Reviewed By: kevin-vigor

Differential Revision: D25699054

fbshipit-source-id: bac1a7a5c13efa5a58ecec11edf72c500b0783b5

Summary: [folly] Add `co_cancelled`, effectively a shorthand for `co_error(OperationCancelled{})`.

Reviewed By: Mizuchi, lewissbaker

Differential Revision: D25627993

fbshipit-source-id: 91f80772a8b179a4de0fe3b29dfe7eecaafb8e1b

Summary: Fix nullptr dereference

Reviewed By: kevin-vigor

Differential Revision: D25687105

fbshipit-source-id: 59b0f3e4adc810f6e1a89447667cd167c52f7fb5

Differential Revision: D25683616

fbshipit-source-id: 7f199b0e43e0a5a76c4cf16412b22abdc28833ac

Summary: Fix `Arena` bytes-used accounting across calls to member `merge`.

Reviewed By: luciang

Differential Revision: D25656949

fbshipit-source-id: b230b0cdbf51b146fd566cbf688f49817bdf874d

Summary: [folly] Rename coro `Error.h` to `Result.h` since it has multiple result types.

Reviewed By: Mizuchi

Differential Revision: D25625178

fbshipit-source-id: 45f8194922b764429969329563a4695b1c13da6f

Summary: Fix `Arena` bytes-used accounting across calls to member `clear` after a sequence of all-large allocations.

Reviewed By: luciang

Differential Revision: D25656875

fbshipit-source-id: e79aca5f58b61bf1bd4790f8badd0dad6063a6ed

Summary: folly::Singleton is used for singletons that manage resources (thread, fds etc.) and it's generally not safe to use previously created folly::Singletons in child process after fork.

Reviewed By: yfeldblum

Differential Revision: D25292667

fbshipit-source-id: 5343d26c72bb9203429a918a3bb5d458c44e9f3b

Summary:
Recently I found that its impossible to access elevated Watchman daemon from non-elevated process on Windows.

```
events.js:174
      throw er; // Unhandled 'error' event
      ^
Error: connect EPERM \\.\pipe\watchman
    at PipeConnectWrap.afterConnect [as oncomplete] (net.js:1106:14)
Emitted 'error' event at:
    at Socket.<anonymous> (C:\open\ovrsource\unity\socialvr\_js\node_modules\fb-watchman\index.js:118:12)
    at Socket.emit (events.js:198:13)
    at emitErrorNT (internal/streams/destroy.js:91:8)
    at emitErrorAndCloseNT (internal/streams/destroy.js:59:3)
    at process._tickCallback (internal/process/next_tick.js:63:19)
```

To fix this, it was suggested by wez to use [his library](https://github.com/wez/EleDo) to force Watchman daemon always start in normal mode on Windows. In this stack of commits I did integrated his library into project and used it to force daemon restart in normal mode when spawned from elevated terminal.

To make it happen, I checked-in library sources and created proxy project which depends on the initial library and contains header bindings and cmake configuration. I did copy pasted Rust cmake macroses from another facebook project - eden, and also created analogue of autogen.sh but for Windows - autogen.cmd.

Pull Request resolved: https://github.com/facebook/watchman/pull/878

Test Plan:
Launch elevated terminal
Start watchman.exe produced from sources
Observe daemon starting and answering
In process monitor, observe watchman.exe process running under user group

Reviewed By: fanzeyi

Differential Revision: D25595879

Pulled By: arhelmus

fbshipit-source-id: 15eb29adcf5bd4a5708b6533a1b2bacbf13f431c

Summary: [Folly] Cut `FOLLY_HAVE_MEMRCHR` since it is now unused.

Reviewed By: Orvid

Differential Revision: D22130149

fbshipit-source-id: b10c5a52354f5c549d96b54e0c165f08b96612b1

Summary: Since this API is discouraged from use, users should call `folly::observer_detail::ObserverManager::waitForAllUpdates` (and face whatever consequences may come with it).

Reviewed By: yfeldblum

Differential Revision: D25629064

fbshipit-source-id: 141b27bbc4f7cf9b628f15f837c38dd4d8a04f31

Reviewed By: zertosh

Differential Revision: D25662961

fbshipit-source-id: f5811a5797fd6dc8733fdf86f35c93d12a08d53a

Summary: Fix `Arena` total-size accounting across calls to `clear`, as reported by member `totalSize`.

Reviewed By: luciang

Differential Revision: D25656867

fbshipit-source-id: b5c7bb0e95199a9fa2c94c04de65b8f494eef146

Summary: Don't use gtest/gtest.h directly.

Reviewed By: yfeldblum

Differential Revision: D25659806

fbshipit-source-id: a8dd0da814465a787ab7904bdd0256f22b6e3ed8