Subject: [PATCH v3] simple-ipc: correct ifdefs when NO_PTHREADS is defined

From: "Jeff Hostetler via GitGitGadget" <[email-masked]>
Date: Thu, 20 May 2021 18:28:10 +0000

From: Jeff Hostetler <[email-masked]>

Simple IPC always requires threads (in addition to various
platform-specific IPC support).  Fix the ifdefs in the Makefile
to define SUPPORTS_SIMPLE_IPC when appropriate.

Previously, the Unix version of the code would only verify that
Unix domain sockets were available.

This problem was reported here:
https://lore.kernel.org/git/[email-masked]/T/#m08be8f1942ea8a2c36cfee0e51cdf06489fdeafc

Reported-by: Randall S. Becker <[email-masked]>
Helped-by: Jeff King <[email-masked]>
Signed-off-by: Jeff Hostetler <[email-masked]>
---
    simple-ipc: correct ifdefs when NO_PTHREADS is defined
    
    Here is V3 of this fixup. I've added fixups for the CMake builds.
    
    Jeff

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-955%2Fjeffhostetler%2Ffixup-simple-ipc-no-pthreads-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-955/jeffhostetler/fixup-simple-ipc-no-pthreads-v3
Pull-Request: https://github.com/gitgitgadget/git/pull/955

Range-diff vs v2:

 1:  119412f52ff5 ! 1:  d4f4170414e3 simple-ipc: correct ifdefs when NO_PTHREADS is defined
     @@ compat/simple-ipc/ipc-win32.c
       
       static int initialize_pipe_name(const char *path, wchar_t *wpath, size_t alloc)
      
     + ## contrib/buildsystems/CMakeLists.txt ##
     +@@ contrib/buildsystems/CMakeLists.txt: endif()
     + 
     + if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
     + 	list(APPEND compat_SOURCES compat/simple-ipc/ipc-shared.c compat/simple-ipc/ipc-win32.c)
     ++	add_compile_definitions(SUPPORTS_SIMPLE_IPC)
     ++	set(SUPPORTS_SIMPLE_IPC 1)
     + else()
     +-	list(APPEND compat_SOURCES compat/simple-ipc/ipc-shared.c compat/simple-ipc/ipc-unix-socket.c)
     ++	# Simple IPC requires both Unix sockets and pthreads on Unix-based systems.
     ++	if(NOT NO_UNIX_SOCKETS AND NOT NO_PTHREADS)
     ++		list(APPEND compat_SOURCES compat/simple-ipc/ipc-shared.c compat/simple-ipc/ipc-unix-socket.c)
     ++		add_compile_definitions(SUPPORTS_SIMPLE_IPC)
     ++		set(SUPPORTS_SIMPLE_IPC 1)
     ++	endif()
     + endif()
     + 
     + set(EXE_EXTENSION ${CMAKE_EXECUTABLE_SUFFIX})
     +@@ contrib/buildsystems/CMakeLists.txt: file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "X='${EXE_EXTENSION}'\n")
     + file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "NO_GETTEXT='${NO_GETTEXT}'\n")
     + file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "RUNTIME_PREFIX='${RUNTIME_PREFIX}'\n")
     + file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "NO_PYTHON='${NO_PYTHON}'\n")
     ++file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "SUPPORTS_SIMPLE_IPC='${SUPPORTS_SIMPLE_IPC}'\n")
     + if(WIN32)
     + 	file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "PATH=\"$PATH:$TEST_DIRECTORY/../compat/vcbuild/vcpkg/installed/x64-windows/bin\"\n")
     + endif()
     +
       ## simple-ipc.h ##
      @@
        * See Documentation/technical/api-simple-ipc.txt

 Makefile                            | 22 ++++++++++++++++++++--
 compat/simple-ipc/ipc-shared.c      | 10 +++++++---
 compat/simple-ipc/ipc-unix-socket.c |  8 ++++++--
 compat/simple-ipc/ipc-win32.c       |  8 ++++++--
 contrib/buildsystems/CMakeLists.txt | 10 +++++++++-
 simple-ipc.h                        |  4 ----
 6 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/Makefile b/Makefile
index 3a2d3c80a81a..ea4c0a77604d 100644
--- a/Makefile
+++ b/Makefile
@@ -1687,13 +1687,31 @@ ifdef NO_UNIX_SOCKETS
 else
 	LIB_OBJS += unix-socket.o
 	LIB_OBJS += unix-stream-server.o
-	LIB_OBJS += compat/simple-ipc/ipc-shared.o
-	LIB_OBJS += compat/simple-ipc/ipc-unix-socket.o
 endif
 
+# Simple IPC requires threads and platform-specific IPC support.
+# Only platforms that have both should include these source files
+# in the build.
+#
+# On Windows-based systems, Simple IPC requires threads and Windows
+# Named Pipes.  These are always available, so Simple IPC support
+# is optional.
+#
+# On Unix-based systems, Simple IPC requires pthreads and Unix
+# domain sockets.  So support is only enabled when both are present.
+#
 ifdef USE_WIN32_IPC
+	BASIC_CFLAGS += -DSUPPORTS_SIMPLE_IPC
 	LIB_OBJS += compat/simple-ipc/ipc-shared.o
 	LIB_OBJS += compat/simple-ipc/ipc-win32.o
+else
+ifndef NO_PTHREADS
+ifndef NO_UNIX_SOCKETS
+	BASIC_CFLAGS += -DSUPPORTS_SIMPLE_IPC
+	LIB_OBJS += compat/simple-ipc/ipc-shared.o
+	LIB_OBJS += compat/simple-ipc/ipc-unix-socket.o
+endif
+endif
 endif
 
 ifdef NO_ICONV
diff --git a/compat/simple-ipc/ipc-shared.c b/compat/simple-ipc/ipc-shared.c
index 1edec8159532..1b9d359ab681 100644
--- a/compat/simple-ipc/ipc-shared.c
+++ b/compat/simple-ipc/ipc-shared.c
@@ -4,7 +4,13 @@
 #include "pkt-line.h"
 #include "thread-utils.h"
 
-#ifdef SUPPORTS_SIMPLE_IPC
+#ifndef SUPPORTS_SIMPLE_IPC
+/*
+ * This source file should only be compiled when Simple IPC is supported.
+ * See the top-level Makefile.
+ */
+#error SUPPORTS_SIMPLE_IPC not defined
+#endif
 
 int ipc_server_run(const char *path, const struct ipc_server_opts *opts,
 		   ipc_server_application_cb *application_cb,
@@ -24,5 +30,3 @@ int ipc_server_run(const char *path, const struct ipc_server_opts *opts,
 
 	return ret;
 }
-
-#endif /* SUPPORTS_SIMPLE_IPC */
diff --git a/compat/simple-ipc/ipc-unix-socket.c b/compat/simple-ipc/ipc-unix-socket.c
index 38689b278df3..1927e6ef4bca 100644
--- a/compat/simple-ipc/ipc-unix-socket.c
+++ b/compat/simple-ipc/ipc-unix-socket.c
@@ -6,8 +6,12 @@
 #include "unix-socket.h"
 #include "unix-stream-server.h"
 
-#ifdef NO_UNIX_SOCKETS
-#error compat/simple-ipc/ipc-unix-socket.c requires Unix sockets
+#ifndef SUPPORTS_SIMPLE_IPC
+/*
+ * This source file should only be compiled when Simple IPC is supported.
+ * See the top-level Makefile.
+ */
+#error SUPPORTS_SIMPLE_IPC not defined
 #endif
 
 enum ipc_active_state ipc_get_active_state(const char *path)
diff --git a/compat/simple-ipc/ipc-win32.c b/compat/simple-ipc/ipc-win32.c
index 8f89c02037e3..8dc7bda087da 100644
--- a/compat/simple-ipc/ipc-win32.c
+++ b/compat/simple-ipc/ipc-win32.c
@@ -4,8 +4,12 @@
 #include "pkt-line.h"
 #include "thread-utils.h"
 
-#ifndef GIT_WINDOWS_NATIVE
-#error This file can only be compiled on Windows
+#ifndef SUPPORTS_SIMPLE_IPC
+/*
+ * This source file should only be compiled when Simple IPC is supported.
+ * See the top-level Makefile.
+ */
+#error SUPPORTS_SIMPLE_IPC not defined
 #endif
 
 static int initialize_pipe_name(const char *path, wchar_t *wpath, size_t alloc)
diff --git a/contrib/buildsystems/CMakeLists.txt b/contrib/buildsystems/CMakeLists.txt
index 75ed198a6a36..a87841340e6a 100644
--- a/contrib/buildsystems/CMakeLists.txt
+++ b/contrib/buildsystems/CMakeLists.txt
@@ -252,8 +252,15 @@ endif()
 
 if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
 	list(APPEND compat_SOURCES compat/simple-ipc/ipc-shared.c compat/simple-ipc/ipc-win32.c)
+	add_compile_definitions(SUPPORTS_SIMPLE_IPC)
+	set(SUPPORTS_SIMPLE_IPC 1)
 else()
-	list(APPEND compat_SOURCES compat/simple-ipc/ipc-shared.c compat/simple-ipc/ipc-unix-socket.c)
+	# Simple IPC requires both Unix sockets and pthreads on Unix-based systems.
+	if(NOT NO_UNIX_SOCKETS AND NOT NO_PTHREADS)
+		list(APPEND compat_SOURCES compat/simple-ipc/ipc-shared.c compat/simple-ipc/ipc-unix-socket.c)
+		add_compile_definitions(SUPPORTS_SIMPLE_IPC)
+		set(SUPPORTS_SIMPLE_IPC 1)
+	endif()
 endif()
 
 set(EXE_EXTENSION ${CMAKE_EXECUTABLE_SUFFIX})
@@ -974,6 +981,7 @@ file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "X='${EXE_EXTENSION}'\n")
 file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "NO_GETTEXT='${NO_GETTEXT}'\n")
 file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "RUNTIME_PREFIX='${RUNTIME_PREFIX}'\n")
 file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "NO_PYTHON='${NO_PYTHON}'\n")
+file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "SUPPORTS_SIMPLE_IPC='${SUPPORTS_SIMPLE_IPC}'\n")
 if(WIN32)
 	file(APPEND ${CMAKE_BINARY_DIR}/GIT-BUILD-OPTIONS "PATH=\"$PATH:$TEST_DIRECTORY/../compat/vcbuild/vcpkg/installed/x64-windows/bin\"\n")
 endif()
diff --git a/simple-ipc.h b/simple-ipc.h
index dc3606e30bd6..2c48a5ee0047 100644
--- a/simple-ipc.h
+++ b/simple-ipc.h
@@ -5,10 +5,6 @@
  * See Documentation/technical/api-simple-ipc.txt
  */
 
-#if defined(GIT_WINDOWS_NATIVE) || !defined(NO_UNIX_SOCKETS)
-#define SUPPORTS_SIMPLE_IPC
-#endif
-
 #ifdef SUPPORTS_SIMPLE_IPC
 #include "pkt-line.h"

base-commit: bf949ade81106fbda068c1fdb2c6fd1cb1babe7e
-- 
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