Generating shared/dynamic libs from Crashpad instead of static

[Matthew Spelman]

Is there a way to have Crashpad generate .so/.dylib/.dll versions of its library files instead of the static .a/.lib? I looked at https://stackoverflow.com/questions/55302553/how-to-build-dynamic-shared-libraries-of-crashpad and https://stackoverflow.com/questions/57486462/how-do-i-build-google-crashpad-into-shared-dynamic-libraries but those only seem to talk about Windows with the /MD flag, and I need to do this on Linux and Mac, as well. Ideally, there would be a way to pass this to GN via the --args flag, since I am calling both GN and Ninja programmatically when I build Crashpad. I tried --args="extra_cflags=\"-shared\"" and --args="extra_cflags=\"-dynamiclib\"" but that didn't seem to work.

[Joshua Peraza]

This line of the BUILD file makes it a static library. Change to `crashpad_loadable_module` to make a shared library. https://source.chromium.org/chromium/chromium/src/+/main:third_party/crashpad/crashpad/client/BUILD.gn;drc=761ff9773d30f6f82382516b47e9f3af2a5e216c;l=17

On Fri, Jul 15, 2022 at 7:07 AM Matthew Spelman <mjs...@gmail.com> wrote:

Is there a way to have Crashpad generate .so/.dylib/.dll versions of its library files instead of the static .a/.lib? I looked at https://stackoverflow.com/questions/55302553/how-to-build-dynamic-shared-libraries-of-crashpad and https://stackoverflow.com/questions/57486462/how-do-i-build-google-crashpad-into-shared-dynamic-libraries but those only seem to talk about Windows with the /MD flag, and I need to do this on Linux and Mac, as well. Ideally, there would be a way to pass this to GN via the --args flag, since I am calling both GN and Ninja programmatically when I build Crashpad. I tried --args="extra_cflags=\"-shared\"" and --args="extra_cflags=\"-dynamiclib\"" but that didn't seem to work.

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[Matthew Spelman]

This fails to link, unfortunately:

[414/488] LINK ./crashpad_database_util
FAILED: crashpad_database_util
g++ -Wl,--as-needed -Wl,-z,noexecstack -pthread -m64 -Wl,-O1 -Wl,--gc-sections -pie -o "./crashpad_database_util" -Wl,--start-group obj/tools/crashpad_database_util.crashpad_database_util.o obj/tools/tool_support.tool_support.o obj/compat/libcompat.a obj/util/libutil.a obj/third_party/mini_chromium/mini_chromium/base/libbase.a   -Wl,--end-group -ldl -lz
/gcc-10.3.0/bin/../lib/gcc/x86_64-pc-linux-gnu/10.3.0/../../../../x86_64-pc-linux-gnu/bin/ld: obj/tools/crashpad_database_util.crashpad_database_util.o: in function `std::unique_ptr<crashpad::CrashReportDatabase::NewReport, std::default_delete<crashpad::CrashReportDatabase::NewReport> >::~unique_ptr()':
crashpad_database_util.cc:(.text._ZNSt10unique_ptrIN8crashpad19CrashReportDatabase9NewReportESt14default_deleteIS2_EED2Ev[_ZNSt10unique_ptrIN8crashpad19CrashReportDatabase9NewReportESt14default_deleteIS2_EED5Ev]+0x21): undefined reference to `crashpad::CrashReportDatabase::NewReport::~NewReport()'
/gcc-10.3.0/bin/../lib/gcc/x86_64-pc-linux-gnu/10.3.0/../../../../x86_64-pc-linux-gnu/bin/ld: obj/tools/crashpad_database_util.crashpad_database_util.o: in function `crashpad::(anonymous namespace)::DatabaseUtilMain(int, char**)':
crashpad_database_util.cc:(.text._ZN8crashpad12_GLOBAL__N_116DatabaseUtilMainEiPPc+0x765): undefined reference to `crashpad::CrashReportDatabase::Initialize(base::FilePath const&)'
/gcc-10.3.0/bin/../lib/gcc/x86_64-pc-linux-gnu/10.3.0/../../../../x86_64-pc-linux-gnu/bin/ld: crashpad_database_util.cc:(.text._ZN8crashpad12_GLOBAL__N_116DatabaseUtilMainEiPPc+0x8e4): undefined reference to `crashpad::CrashReportDatabase::Report::Report()'
/gcc-10.3.0/bin/../lib/gcc/x86_64-pc-linux-gnu/10.3.0/../../../../x86_64-pc-linux-gnu/bin/ld: crashpad_database_util.cc:(.text._ZN8crashpad12_GLOBAL__N_116DatabaseUtilMainEiPPc+0xa06): undefined reference to `crashpad::CrashReportDatabase::InitializeWithoutCreating(base::FilePath const&)'
/gcc-10.3.0/bin/../lib/gcc/x86_64-pc-linux-gnu/10.3.0/../../../../x86_64-pc-linux-gnu/bin/ld: crashpad_database_util.cc:(.text._ZN8crashpad12_GLOBAL__N_116DatabaseUtilMainEiPPc+0xa52): undefined reference to `crashpad::Settings::GetClientID(crashpad::UUID*)'
/gcc-10.3.0/bin/../lib/gcc/x86_64-pc-linux-gnu/10.3.0/../../../../x86_64-pc-linux-gnu/bin/ld: crashpad_database_util.cc:(.text._ZN8crashpad12_GLOBAL__N_116DatabaseUtilMainEiPPc+0xb66): undefined reference to `crashpad::Settings::SetLastUploadAttemptTime(long)'
/gcc-10.3.0/bin/../lib/gcc/x86_64-pc-linux-gnu/10.3.0/../../../../x86_64-pc-linux-gnu/bin/ld: crashpad_database_util.cc:(.text._ZN8crashpad12_GLOBAL__N_116DatabaseUtilMainEiPPc+0xd3d): undefined reference to `crashpad::Settings::GetUploadsEnabled(bool*)'
/gcc-10.3.0/bin/../lib/gcc/x86_64-pc-linux-gnu/10.3.0/../../../../x86_64-pc-linux-gnu/bin/ld: crashpad_database_util.cc:(.text._ZN8crashpad12_GLOBAL__N_116DatabaseUtilMainEiPPc+0xdd2): undefined reference to `crashpad::Settings::GetLastUploadAttemptTime(long*)'
/gcc-10.3.0/bin/../lib/gcc/x86_64-pc-linux-gnu/10.3.0/../../../../x86_64-pc-linux-gnu/bin/ld: crashpad_database_util.cc:(.text._ZN8crashpad12_GLOBAL__N_116DatabaseUtilMainEiPPc+0xfd5): undefined reference to `crashpad::Settings::SetUploadsEnabled(bool)'
collect2: error: ld returned 1 exit status

Do I need to convert any other Crashpad modules besides client to a loadable_module? Or are there any other compiler flags I need to specify?

[Mark Mentovai]

Nobody’s ever gone to the trouble of uglifying Crashpad’s source code with all of the visibility macros that would be needed to make this work. You could hack it up with -fvisibility=default (or remove our default -fvisibility=hidden) if you were determined to do something quick and dirty.

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[Matthew Spelman]

Thanks, I messed around with it but I think I'll stick with static linking for now.