fix: support musl on Linux

.github/workflows/ci.yml

@@ -86,6 +86,18 @@ jobs:
           - name: Linux (GCC 13.3.0 + code-checker + valgrind)
             os: ubuntu-24.04
             RUN_ANALYZER: code-checker,valgrind
+          - name: Linux (GCC + musl + libunwind)
+            os: ubuntu-latest
+            container: alpine:3.21
+            APK_PACKAGES: libunwind-dev libunwind-static
+            CC: gcc
+            CXX: g++
+          - name: Linux (clang + musl + llvm-libunwind)
+            os: ubuntu-latest
+            container: alpine:3.21
+            APK_PACKAGES: clang llvm-libunwind-dev llvm-libunwind-static
+            CC: clang
+            CXX: clang++
           - name: macOS 14 (xcode llvm)
             os: macos-14
             ERROR_ON_WARNINGS: 1
@@ -135,6 +147,7 @@ jobs:
 
     name: ${{ matrix.name }}
     runs-on: ${{ matrix.os }}
+    container: ${{ matrix.container }}
 
     env:
       TEST_X86: ${{ matrix.TEST_X86 }}
@@ -149,16 +162,25 @@ jobs:
       VS_GENERATOR_TOOLSET: ${{ matrix.VS_GENERATOR_TOOLSET }}
 
     steps:
+      - name: Installing Alpine Linux Dependencies
+        if: ${{ contains(matrix.container, 'alpine') }}
+        run: |
+          apk update
+          apk add bash build-base cargo cmake curl curl-dev git icu linux-headers mitmproxy perl python3-dev sudo ${{ matrix.APK_PACKAGES }}
+          curl -sSL --retry 5 https://dot.net/v1/dotnet-install.sh | bash -eo pipefail /dev/stdin --channel 8.0 --install-dir /usr/share/dotnet
+          ln -s /usr/share/dotnet/dotnet /usr/local/bin/dotnet
+
       - uses: actions/checkout@v4
         with:
           submodules: recursive
       - uses: actions/setup-python@v5
+        if: ${{ !matrix.container }}
         with:
           python-version: "3.11"
           cache: "pip"
 
       - name: Installing Linux Dependencies
-        if: ${{ runner.os == 'Linux' && matrix.os != 'ubuntu-22.04' && !env['TEST_X86'] }}
+        if: ${{ runner.os == 'Linux' && matrix.os != 'ubuntu-22.04' && !env['TEST_X86'] && !matrix.container }}
         run: |
           sudo apt update
           sudo apt install cmake clang-19 llvm g++-12 valgrind zlib1g-dev libcurl4-openssl-dev
@@ -173,13 +195,13 @@ jobs:
           sudo make install
 
       - name: Installing Linux GCC 9.4.0 Dependencies
-        if: ${{ runner.os == 'Linux' && matrix.os == 'ubuntu-22.04' && !env['TEST_X86'] }}
+        if: ${{ runner.os == 'Linux' && matrix.os == 'ubuntu-22.04' && !env['TEST_X86'] && !matrix.container }}
         run: |
           sudo apt update
           sudo apt install cmake llvm kcov g++ valgrind zlib1g-dev libcurl4-openssl-dev
 
       - name: Installing Linux 32-bit Dependencies
-        if: ${{ runner.os == 'Linux' && env['TEST_X86'] }}
+        if: ${{ runner.os == 'Linux' && env['TEST_X86'] && !matrix.container }}
         run: |
           sudo dpkg --add-architecture i386
           sudo apt update
@@ -252,6 +274,16 @@ jobs:
           cat /etc/hosts
         shell: bash
 
+      - name: Prepare env for Alpine Linux
+        if: ${{ contains(matrix.container, 'alpine') }}
+        run: |
+          apk add moreutils
+          # comment out "::1 localhost ..." to avoid conflicts with proxy tests
+          sed '/^::1/ s/^/#/' /etc/hosts | sponge /etc/hosts
+          python3 -m venv .venv --system-site-packages
+          source .venv/bin/activate
+          echo "PATH=$PATH" >> $GITHUB_ENV
+
       - name: Test
         shell: bash
         run: |

CHANGELOG.md

@@ -9,6 +9,7 @@
 **Fixes**:
 
 - Remove compile-time check for the `libcurl` feature `AsynchDNS`. ([#1206](https://github.com/getsentry/sentry-native/pull/1206))
+- Support musl on Linux ([#1233](https://github.com/getsentry/sentry-native/pull/1233))
 
 ## 0.8.4
 

CMakeLists.txt

@@ -97,6 +97,15 @@ if(LINUX)
 		set(CMAKE_ASM_FLAGS  "${CMAKE_ASM_FLAGS} -m32 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE")
 		set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIB64_PATHS OFF)
 	endif()
+
+        execute_process(
+                COMMAND ${CMAKE_C_COMPILER} -dumpmachine
+                OUTPUT_VARIABLE TARGET_TRIPLET
+                OUTPUT_STRIP_TRAILING_WHITESPACE
+        )
+        if(TARGET_TRIPLET MATCHES "musl")
+                set(MUSL TRUE)
+        endif()
 endif()
 
 # CMAKE_POSITION_INDEPENDENT_CODE must be set BEFORE adding any libraries (including subprojects)
@@ -199,6 +208,8 @@ endif()
 
 if(ANDROID)
 	set(SENTRY_WITH_LIBUNWINDSTACK TRUE)
+elseif(MUSL)
+	set(SENTRY_WITH_LIBUNWIND TRUE)
 elseif(NOT WIN32)
 	set(SENTRY_WITH_LIBBACKTRACE TRUE)
 endif()
@@ -504,6 +515,15 @@ if(SENTRY_WITH_LIBUNWINDSTACK)
 	endif()
 endif()
 
+if(SENTRY_WITH_LIBUNWIND)
+	if(LINUX)
+		find_path(LIBUNWIND_INCLUDE_DIR libunwind.h PATH_SUFFIXES libunwind REQUIRED)
+		find_library(LIBUNWIND_LIBRARY unwind REQUIRED)
+		target_include_directories(sentry PRIVATE ${LIBUNWIND_INCLUDE_DIR})
+		target_link_libraries(sentry PRIVATE ${LIBUNWIND_LIBRARY})
+	endif()
+endif()
+
 if(SENTRY_BACKEND_CRASHPAD)
 	if(SENTRY_BUILD_SHARED_LIBS)
 		set(CRASHPAD_ENABLE_INSTALL OFF CACHE BOOL "Enable crashpad installation" FORCE)

src/CMakeLists.txt

@@ -144,6 +144,12 @@ if(SENTRY_WITH_LIBBACKTRACE)
 	)
 endif()
 
+if(SENTRY_WITH_LIBUNWIND)
+	target_compile_definitions(sentry PRIVATE SENTRY_WITH_UNWINDER_LIBUNWIND)
+	sentry_target_sources_cwd(sentry
+			unwinder/sentry_unwinder_libunwind.c
+	)
+endif()
 if(SENTRY_WITH_LIBUNWINDSTACK)
 	target_compile_definitions(sentry PRIVATE SENTRY_WITH_UNWINDER_LIBUNWINDSTACK)
 	sentry_target_sources_cwd(sentry

src/unwinder/sentry_unwinder.c

@@ -15,6 +15,7 @@
 DEFINE_UNWINDER(libunwindstack);
 DEFINE_UNWINDER(libbacktrace);
 DEFINE_UNWINDER(dbghelp);
+DEFINE_UNWINDER(libunwind);
 
 static size_t
 unwind_stack(
@@ -28,6 +29,9 @@ unwind_stack(
 #endif
 #ifdef SENTRY_WITH_UNWINDER_DBGHELP
     TRY_UNWINDER(dbghelp);
+#endif
+#ifdef SENTRY_WITH_UNWINDER_LIBUNWIND
+    TRY_UNWINDER(libunwind);
 #endif
     return 0;
 }

src/unwinder/sentry_unwinder_libunwind.c

@@ -0,0 +1,46 @@
+#include "sentry_boot.h"
+#include "sentry_logger.h"
+#define UNW_LOCAL_ONLY
+#include <libunwind.h>
+
+size_t
+sentry__unwind_stack_libunwind(
+    void *addr, const sentry_ucontext_t *uctx, void **ptrs, size_t max_frames)
+{
+    if (addr) {
+        return 0;
+    }
+
+    unw_cursor_t cursor;
+    if (uctx) {
+        int ret = unw_init_local(&cursor, (unw_context_t *)uctx->user_context);
+        if (ret != 0) {
+            SENTRY_WARN("Failed to initialize libunwind with ucontext");
+            return 0;
+        }
+    } else {
+        unw_context_t uc;
+        int ret = unw_getcontext(&uc);
+        if (ret != 0) {
+            SENTRY_WARN("Failed to retrieve context with libunwind");
+            return 0;
+        }
+
+        ret = unw_init_local(&cursor, &uc);
+        if (ret != 0) {
+            SENTRY_WARN("Failed to initialize libunwind with local context");
+            return 0;
+        }
+    }
+
+    size_t frame_idx = 0;
+    while (unw_step(&cursor) > 0 && frame_idx < max_frames - 1) {
+        unw_word_t ip = 0;
+        unw_get_reg(&cursor, UNW_REG_IP, &ip);
+        ptrs[frame_idx] = (void *)ip;
+        unw_word_t sp = 0;
+        unw_get_reg(&cursor, UNW_REG_SP, &sp);
+        frame_idx++;
+    }
+    return frame_idx + 1;
+}