[oe] [meta-oe][PATCH] breakpad: disable calls to getcontext() with musl

[Andre McCurdy]

On Wed, Jan 24, 2018 at 11:49 PM, Khem Raj <raj.khem at gmail.com> wrote:
> On Wed, Jan 24, 2018 at 3:26 PM, Andre McCurdy <armccurdy at gmail.com> wrote:
>> Musl does not currently provide getcontext().
>
> perhaps its better to declare breakpad incompatible with musl instead
> since if it builds it will raise the hopes of users to work well at runtime
> which it wont.

I'm using a distro which unconditionally enables breakpad and it would
take some surgery to disable it. Unfortunately the distro maintainers
are generally slow and unresponsive to patches so there's a good
chance I'd end up carrying the changes to disable breakpad in my own
tree.

At least for me, it's better to have a breakpad which builds but
doesn't work rather than not building at all.

>> Signed-off-by: Andre McCurdy <armccurdy at gmail.com>
>> ---
>>  ...001-disable-calls-to-getcontext-with-musl.patch | 52 ++++++++++++++++++++++
>>  meta-oe/recipes-devtools/breakpad/breakpad_git.bb  |  1 +
>>  2 files changed, 53 insertions(+)
>>  create mode 100644 meta-oe/recipes-devtools/breakpad/breakpad/0001-disable-calls-to-getcontext-with-musl.patch
>>
>> diff --git a/meta-oe/recipes-devtools/breakpad/breakpad/0001-disable-calls-to-getcontext-with-musl.patch b/meta-oe/recipes-devtools/breakpad/breakpad/0001-disable-calls-to-getcontext-with-musl.patch
>> new file mode 100644
>> index 0000000..c762754
>> --- /dev/null
>> +++ b/meta-oe/recipes-devtools/breakpad/breakpad/0001-disable-calls-to-getcontext-with-musl.patch
>> @@ -0,0 +1,52 @@
>> +From 57ecf7205feedd23f901e1bb9d193787e559e433 Mon Sep 17 00:00:00 2001
>> +From: Andre McCurdy <armccurdy at gmail.com>
>> +Date: Tue, 23 Jan 2018 15:13:26 -0800
>> +Subject: [PATCH] disable calls to getcontext() with musl
>> +
>> +Signed-off-by: Andre McCurdy <armccurdy at gmail.com>
>> +---
>> + src/client/linux/handler/exception_handler.cc | 17 +++++++++++++++++
>> + 1 file changed, 17 insertions(+)
>> +
>> +diff --git a/src/client/linux/handler/exception_handler.cc b/src/client/linux/handler/exception_handler.cc
>> +index cca023f..f3e460c 100644
>> +--- a/src/client/linux/handler/exception_handler.cc
>> ++++ b/src/client/linux/handler/exception_handler.cc
>> +@@ -495,7 +495,19 @@ bool ExceptionHandler::SimulateSignalDelivery(int sig) {
>> +   siginfo.si_code = SI_USER;
>> +   siginfo.si_pid = getpid();
>> +   ucontext_t context;
>> ++#if defined(__GLIBC__)
>> +   getcontext(&context);
>> ++#else
>> ++  // Extreme hack: Allow musl builds to compile - but don't expect them to work.
>> ++  // Although musl provides a definition for getcontext() in ucontext.h (which
>> ++  // enough to build libbreakpad_client) musl does not provide a corresponding
>> ++  // getcontext() function, so builds will fail when attempting to link anything
>> ++  // with libbreakpad_client. Disabling calls to getcontext() is a temporary
>> ++  // hack. The real fix is probably to enable Breakpad's own implementation of
>> ++  // getcontext() when building for musl (it's currently only enabled when
>> ++  // building for Android).
>> ++  memset (&context, 0, sizeof(context));
>> ++#endif
>> +   return HandleSignal(sig, &siginfo, &context);
>> + }
>> +
>> +@@ -680,9 +692,14 @@ bool ExceptionHandler::WriteMinidump() {
>> +   sys_prctl(PR_SET_DUMPABLE, 1, 0, 0, 0);
>> +
>> +   CrashContext context;
>> ++#if defined(__GLIBC__)
>> +   int getcontext_result = getcontext(&context.context);
>> +   if (getcontext_result)
>> +     return false;
>> ++#else
>> ++  // Extreme hack - see comments above.
>> ++  memset (&context.context, 0, sizeof(&context.context));
>> ++#endif
>> +
>> + #if defined(__i386__)
>> +   // In CPUFillFromUContext in minidumpwriter.cc the stack pointer is retrieved
>> +--
>> +1.9.1
>> +
>> diff --git a/meta-oe/recipes-devtools/breakpad/breakpad_git.bb b/meta-oe/recipes-devtools/breakpad/breakpad_git.bb
>> index 5f6d82c..d9773c9 100644
>> --- a/meta-oe/recipes-devtools/breakpad/breakpad_git.bb
>> +++ b/meta-oe/recipes-devtools/breakpad/breakpad_git.bb
>> @@ -41,6 +41,7 @@ SRC_URI = "git://github.com/google/breakpad;name=breakpad \
>>             file://0005-md2core-Replace-basename.patch \
>>             file://0002-Use-_fpstate-instead-of-_libc_fpstate-on-linux.patch \
>>             file://mcontext.patch \
>> +           file://0001-disable-calls-to-getcontext-with-musl.patch \
>>             file://0001-lss-Match-syscalls-to-match-musl.patch;patchdir=src/third_party/lss \
>>             file://mips_asm_sgidefs.patch;patchdir=src/third_party/lss \
>>  "
>> --
>> 1.9.1
>>
>> --
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