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

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

[Jeff Hostetler via GitGitGadget]

From: Jeff Hostetler <jeffhost@microsoft.com>

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/YKN5lXs4AoK%2FJFTO@coredump.intra.peff.net/T/#m08be8f1942ea8a2c36cfee0e51cdf06489fdeafc

Reported-by: Randall S. Becker <rsbecker@nexbridge.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
    simple-ipc: correct ifdefs when NO_PTHREADS is defined
    
    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/YKN5lXs4AoK%2FJFTO@coredump.intra.peff.net/T/#m08be8f1942ea8a2c36cfee0e51cdf06489fdeafc
    
    Reported-by: Randall S. Becker rsbecker@nexbridge.com Helped-by: Jeff
    King peff@peff.net Signed-off-by: Jeff Hostetler jeffhost@microsoft.com

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-955%2Fjeffhostetler%2Ffixup-simple-ipc-no-pthreads-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-955/jeffhostetler/fixup-simple-ipc-no-pthreads-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/955

 Makefile                            | 14 ++++++++++++--
 compat/simple-ipc/ipc-unix-socket.c |  8 ++++++++
 compat/simple-ipc/ipc-win32.c       |  4 ++++
 simple-ipc.h                        |  4 ----
 4 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 3a2d3c80a81a..30df67fd62eb 100644
--- a/Makefile
+++ b/Makefile
@@ -1687,13 +1687,23 @@ 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.
+# (We group all Unix variants in the top-level else because Windows
+# also defines NO_UNIX_SOCKETS.)
 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-unix-socket.c b/compat/simple-ipc/ipc-unix-socket.c
index 38689b278df3..c23b17973983 100644
--- a/compat/simple-ipc/ipc-unix-socket.c
+++ b/compat/simple-ipc/ipc-unix-socket.c
@@ -6,10 +6,16 @@
 #include "unix-socket.h"
 #include "unix-stream-server.h"
 
+#ifdef SUPPORTS_SIMPLE_IPC
+
 #ifdef NO_UNIX_SOCKETS
 #error compat/simple-ipc/ipc-unix-socket.c requires Unix sockets
 #endif
 
+#ifdef NO_PTHREADS
+#error compat/simple-ipc/ipc-unix-socket.c requires pthreads
+#endif
+
 enum ipc_active_state ipc_get_active_state(const char *path)
 {
 	enum ipc_active_state state = IPC_STATE__OTHER_ERROR;
@@ -997,3 +1003,5 @@ void ipc_server_free(struct ipc_server_data *server_data)
 	free(server_data->fifo_fds);
 	free(server_data);
 }
+
+#endif /* SUPPORTS_SIMPLE_IPC */
diff --git a/compat/simple-ipc/ipc-win32.c b/compat/simple-ipc/ipc-win32.c
index 8f89c02037e3..958bb562ebb6 100644
--- a/compat/simple-ipc/ipc-win32.c
+++ b/compat/simple-ipc/ipc-win32.c
@@ -4,6 +4,8 @@
 #include "pkt-line.h"
 #include "thread-utils.h"
 
+#ifdef SUPPORTS_SIMPLE_IPC
+
 #ifndef GIT_WINDOWS_NATIVE
 #error This file can only be compiled on Windows
 #endif
@@ -749,3 +751,5 @@ void ipc_server_free(struct ipc_server_data *server_data)
 
 	free(server_data);
 }
+
+#endif /* SUPPORTS_SIMPLE_IPC */
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
-- 
gitgitgadget

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

[Junio C Hamano]

"Jeff Hostetler via GitGitGadget" <gitgitgadget@gmail.com> writes:

> +# Simple-ipc requires threads and platform-specific IPC support.
> +# (We group all Unix variants in the top-level else because Windows
> +# also defines NO_UNIX_SOCKETS.)
>  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

OK, so "!defined(NO_PTHREADS) && !defined(NO_UNIX_SOCKETS)" is the
requirement for SIMPLE_IPC unless you are on Windows.

> diff --git a/compat/simple-ipc/ipc-unix-socket.c b/compat/simple-ipc/ipc-unix-socket.c
> index 38689b278df3..c23b17973983 100644
> --- a/compat/simple-ipc/ipc-unix-socket.c
> +++ b/compat/simple-ipc/ipc-unix-socket.c
> @@ -6,10 +6,16 @@
>  #include "unix-socket.h"
>  #include "unix-stream-server.h"
>  
> +#ifdef SUPPORTS_SIMPLE_IPC
> +
>  #ifdef NO_UNIX_SOCKETS
>  #error compat/simple-ipc/ipc-unix-socket.c requires Unix sockets
>  #endif
>  
> +#ifdef NO_PTHREADS
> +#error compat/simple-ipc/ipc-unix-socket.c requires pthreads
> +#endif
> +

Do we want to duplicate the requirement here and risk them drifting
apart?

> @@ -997,3 +1003,5 @@ void ipc_server_free(struct ipc_server_data *server_data)
>  	free(server_data->fifo_fds);
>  	free(server_data);
>  }
> +
> +#endif /* SUPPORTS_SIMPLE_IPC */

If anything, I do not think we want a huge #ifdef/#endif around the
whole file.  Feeding this source to your compiler when these three C
proprocessor macros do not agree with its use is an error, so perhaps
lose all of these #ifdef/#endif around the three macros and refer human
readers to the top-level Makefile with a comment, e.g.

/*
 * Non Windows platforms need !NO_UNIX_SOCKETS and !NO_PTHREADS
 * to compile and use this file.  See the top-level Makefile.
 */

if we really wanted to have a way to help builders identify the
reason why their build is failing.

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

[Jeff Hostetler]

On 5/18/21 8:48 PM, Junio C Hamano wrote:
> "Jeff Hostetler via GitGitGadget" <gitgitgadget@gmail.com> writes:
> 
>> +# Simple-ipc requires threads and platform-specific IPC support.
>> +# (We group all Unix variants in the top-level else because Windows
>> +# also defines NO_UNIX_SOCKETS.)
>>   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
> 
> OK, so "!defined(NO_PTHREADS) && !defined(NO_UNIX_SOCKETS)" is the
> requirement for SIMPLE_IPC unless you are on Windows.
> 
>> diff --git a/compat/simple-ipc/ipc-unix-socket.c b/compat/simple-ipc/ipc-unix-socket.c
>> index 38689b278df3..c23b17973983 100644
>> --- a/compat/simple-ipc/ipc-unix-socket.c
>> +++ b/compat/simple-ipc/ipc-unix-socket.c
>> @@ -6,10 +6,16 @@
>>   #include "unix-socket.h"
>>   #include "unix-stream-server.h"
>>   
>> +#ifdef SUPPORTS_SIMPLE_IPC
>> +
>>   #ifdef NO_UNIX_SOCKETS
>>   #error compat/simple-ipc/ipc-unix-socket.c requires Unix sockets
>>   #endif
>>   
>> +#ifdef NO_PTHREADS
>> +#error compat/simple-ipc/ipc-unix-socket.c requires pthreads
>> +#endif
>> +
> 
> Do we want to duplicate the requirement here and risk them drifting
> apart?
> 
>> @@ -997,3 +1003,5 @@ void ipc_server_free(struct ipc_server_data *server_data)
>>   	free(server_data->fifo_fds);
>>   	free(server_data);
>>   }
>> +
>> +#endif /* SUPPORTS_SIMPLE_IPC */
> 
> If anything, I do not think we want a huge #ifdef/#endif around the
> whole file.  Feeding this source to your compiler when these three C
> proprocessor macros do not agree with its use is an error, so perhaps
> lose all of these #ifdef/#endif around the three macros and refer human
> readers to the top-level Makefile with a comment, e.g.
> 
> /*
>   * Non Windows platforms need !NO_UNIX_SOCKETS and !NO_PTHREADS
>   * to compile and use this file.  See the top-level Makefile.
>   */
> 
> if we really wanted to have a way to help builders identify the
> reason why their build is failing.
> 

Would it be better to just have something like the following at the
top of the source files and leave the details to the Makefile:


#ifndef SUPPORTS_SIMPLE_IPC
/*
  * This source file should only be included when Simple IPC
  * is supported.  See the top-level Makefile.
  */
#error SUPPORTS_SIMPLE_IPC not defined
#endif

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

[Junio C Hamano]

Jeff Hostetler <git@jeffhostetler.com> writes:

>>>   #ifdef NO_UNIX_SOCKETS
>>>   #error compat/simple-ipc/ipc-unix-socket.c requires Unix sockets
>>>   #endif
>>>   +#ifdef NO_PTHREADS
>>> +#error compat/simple-ipc/ipc-unix-socket.c requires pthreads
>>> +#endif
>>> +
>> Do we want to duplicate the requirement here and risk them drifting
>> apart?
>>  ...
> Would it be better to just have something like the following at the
> top of the source files and leave the details to the Makefile:
>
>
> #ifndef SUPPORTS_SIMPLE_IPC
> /*
>  * This source file should only be included when Simple IPC
>  * is supported.  See the top-level Makefile.
>  */
> #error SUPPORTS_SIMPLE_IPC not defined
> #endif

Yeah, that is a much better message, with even less duplication,
than what I sent.

I do not think #ifndef/#error/#endif adds much value, though.  After
all, the Makefile does not even tell us to feed this file to the
compiler when the C preprocessor macro is not defined, so presumably
whoever hits the #error knows s/he is doing something not supported,
and the point of the new message is to help those who we failed by
leaving the rest of the source file unbuildable even when we defined
the C preprocessor macro in the Makefile (like the mistaken
dependency on pthreads that we missed).

Thanks.

[PATCH v2] simple-ipc: correct ifdefs when NO_PTHREADS is defined

[Jeff Hostetler via GitGitGadget]

From: Jeff Hostetler <jeffhost@microsoft.com>

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/YKN5lXs4AoK%2FJFTO@coredump.intra.peff.net/T/#m08be8f1942ea8a2c36cfee0e51cdf06489fdeafc

Reported-by: Randall S. Becker <rsbecker@nexbridge.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
    simple-ipc: correct ifdefs when NO_PTHREADS is defined
    
    Here is V2 of this fixup. I've removed the whole file ifdefs and
    replaced them with a simple #ifndef/#error/#endif as a warning.
    
    Jeff

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-955%2Fjeffhostetler%2Ffixup-simple-ipc-no-pthreads-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-955/jeffhostetler/fixup-simple-ipc-no-pthreads-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/955

Range-diff vs v1:

 1:  4adcf35ea6e4 ! 1:  119412f52ff5 simple-ipc: correct ifdefs when NO_PTHREADS is defined
     @@ Makefile: ifdef NO_UNIX_SOCKETS
      -	LIB_OBJS += compat/simple-ipc/ipc-unix-socket.o
       endif
       
     -+# Simple-ipc requires threads and platform-specific IPC support.
     -+# (We group all Unix variants in the top-level else because Windows
     -+# also defines NO_UNIX_SOCKETS.)
     ++# 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
     @@ Makefile: ifdef NO_UNIX_SOCKETS
       
       ifdef NO_ICONV
      
     + ## compat/simple-ipc/ipc-shared.c ##
     +@@
     + #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,
     +@@ compat/simple-ipc/ipc-shared.c: int ipc_server_run(const char *path, const struct ipc_server_opts *opts,
     + 
     + 	return ret;
     + }
     +-
     +-#endif /* SUPPORTS_SIMPLE_IPC */
     +
       ## compat/simple-ipc/ipc-unix-socket.c ##
      @@
       #include "unix-socket.h"
       #include "unix-stream-server.h"
       
     -+#ifdef SUPPORTS_SIMPLE_IPC
     -+
     - #ifdef NO_UNIX_SOCKETS
     - #error compat/simple-ipc/ipc-unix-socket.c requires Unix sockets
     +-#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
       
     -+#ifdef NO_PTHREADS
     -+#error compat/simple-ipc/ipc-unix-socket.c requires pthreads
     -+#endif
     -+
       enum ipc_active_state ipc_get_active_state(const char *path)
     - {
     - 	enum ipc_active_state state = IPC_STATE__OTHER_ERROR;
     -@@ compat/simple-ipc/ipc-unix-socket.c: void ipc_server_free(struct ipc_server_data *server_data)
     - 	free(server_data->fifo_fds);
     - 	free(server_data);
     - }
     -+
     -+#endif /* SUPPORTS_SIMPLE_IPC */
      
       ## compat/simple-ipc/ipc-win32.c ##
      @@
       #include "pkt-line.h"
       #include "thread-utils.h"
       
     -+#ifdef SUPPORTS_SIMPLE_IPC
     -+
     - #ifndef GIT_WINDOWS_NATIVE
     - #error This file can only be compiled on Windows
     +-#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
     -@@ compat/simple-ipc/ipc-win32.c: void ipc_server_free(struct ipc_server_data *server_data)
       
     - 	free(server_data);
     - }
     -+
     -+#endif /* SUPPORTS_SIMPLE_IPC */
     + static int initialize_pipe_name(const char *path, wchar_t *wpath, size_t alloc)
      
       ## simple-ipc.h ##
      @@


 Makefile                            | 22 ++++++++++++++++++++--
 compat/simple-ipc/ipc-shared.c      | 10 +++++++---
 compat/simple-ipc/ipc-unix-socket.c |  8 ++++++--
 compat/simple-ipc/ipc-win32.c       |  8 ++++++--
 simple-ipc.h                        |  4 ----
 5 files changed, 39 insertions(+), 13 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/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
-- 
gitgitgadget

Re: [PATCH v2] simple-ipc: correct ifdefs when NO_PTHREADS is defined

[Jeff Hostetler]

On 5/20/21 10:22 AM, Jeff Hostetler via GitGitGadget wrote:
> From: Jeff Hostetler <jeffhost@microsoft.com>
> 
> 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.
> 

I got in a hurry this morning and forgot to update the CMake script.
I'll look at that now.

Jeff

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

[Jeff Hostetler via GitGitGadget]

From: Jeff Hostetler <jeffhost@microsoft.com>

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/YKN5lXs4AoK%2FJFTO@coredump.intra.peff.net/T/#m08be8f1942ea8a2c36cfee0e51cdf06489fdeafc

Reported-by: Randall S. Becker <rsbecker@nexbridge.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
    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
-- 
gitgitgadget

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

[Junio C Hamano]

"Jeff Hostetler via GitGitGadget" <gitgitgadget@gmail.com> writes:

>  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.

The last part for windows feels funny in that even if they were not
always available, the builder can still choose to compile Simple IPC
support out, hence it is optional (this is true for both Windows and
others).  In other words, "prereqs are always satisified" does not
lead to "hence it is optional".

But let's leave it as-is.  We could rewrite it to "..., so Simple
IPC is always enabled", though.

> +#
> +# On Unix-based systems, Simple IPC requires pthreads and Unix
> +# domain sockets.  So support is only enabled when both are present.

Other than that, looks good to me.

Will queue.