[PATCH v2 1/6] common-main.o: move non-trace2 exit() behavior out of trace2.c

From

Ævar Arnfjörð Bjarmason <avarab@gmail.com>

Date

May 31, 2022, 16:58 UTC

Message-ID

<patch-v2-1.6-d446e4679d4-20220531T164806Z-avarab@gmail.com>

In-Reply-To

<cover-v2-0.6-00000000000-20220531T164806Z-avarab@gmail.com>

1. https://man7.org/linux/man-pages/man3/exit.3.html
2. https://man7.org/linux/man-pages/man2/wait.2.html

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 common-main.c     | 19 +++++++++++++++++--
 git-compat-util.h | 12 ++++++++++--
 trace2.c          |  8 ++------
 trace2.h          |  8 +-------
 4 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/common-main.c b/common-main.c
index 29fb7452f8a..bb0100f6024 100644
--- a/common-main.c
+++ b/common-main.c
@@ -56,9 +56,24 @@ int main(int argc, const char **argv)
 	result = cmd_main(argc, argv);
 
 	/*
-	 * We define exit() to call trace2_cmd_exit_fl() in
-	 * git-compat-util.h. Whether we reach this or exit()
+	 * We define exit() to call common_exit(), which will in turn
+	 * call trace2_cmd_exit_fl(). Whether we reach this or exit()
 	 * elsewhere we'll always run our trace2 exit handler.
 	 */
 	exit(result);
 }
+
+int common_exit(const char *file, int line, int code)
+{
+	/*
+	 * For non-POSIX systems: Take the lowest 8 bits of the "code"
+	 * to e.g. turn -1 into 255. On a POSIX system this is
+	 * redundant, see exit(3) and wait(2), but as it doesn't harm
+	 * anything there we don't need to guard this with an "ifdef".
+	 */
+	code &= 0xff;
+
+	trace2_cmd_exit_fl(file, line, code);
+
+	return code;
+}
diff --git a/git-compat-util.h b/git-compat-util.h
index 96293b6c43a..a446a363de2 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1447,12 +1447,20 @@ static inline int is_missing_file_error(int errno_)
 
 int cmd_main(int, const char **);
 
+/**
+ * The exit() function is defined as common_exit() in
+ * git-compat-util.h.
+ *
+ * Intercepting the exit() allows us to hook in at-exit behavior, such
+ * emitting trace2 logging before calling the real exit().
+ */
+int common_exit(const char *file, int line, int code);
+
 /*
  * Intercept all calls to exit() and route them to trace2 to
  * optionally emit a message before calling the real exit().
  */
-int trace2_cmd_exit_fl(const char *file, int line, int code);
-#define exit(code) exit(trace2_cmd_exit_fl(__FILE__, __LINE__, (code)))
+#define exit(code) exit(common_exit(__FILE__, __LINE__, (code)))
 
 /*
  * You can mark a stack variable with UNLEAK(var) to avoid it being
diff --git a/trace2.c b/trace2.c
index e01cf77f1a8..0c0a11e07d5 100644
--- a/trace2.c
+++ b/trace2.c
@@ -202,17 +202,15 @@ void trace2_cmd_start_fl(const char *file, int line, const char **argv)
 					    argv);
 }
 
-int trace2_cmd_exit_fl(const char *file, int line, int code)
+void trace2_cmd_exit_fl(const char *file, int line, int code)
 {
 	struct tr2_tgt *tgt_j;
 	int j;
 	uint64_t us_now;
 	uint64_t us_elapsed_absolute;
 
-	code &= 0xff;
-
 	if (!trace2_enabled)
-		return code;
+		return;
 
 	trace_git_fsync_stats();
 	trace2_collect_process_info(TRACE2_PROCESS_INFO_EXIT);
@@ -226,8 +224,6 @@ int trace2_cmd_exit_fl(const char *file, int line, int code)
 		if (tgt_j->pfn_exit_fl)
 			tgt_j->pfn_exit_fl(file, line, us_elapsed_absolute,
 					   code);
-
-	return code;
 }
 
 void trace2_cmd_error_va_fl(const char *file, int line, const char *fmt,
diff --git a/trace2.h b/trace2.h
index 1b109f57d0a..88d906ea830 100644
--- a/trace2.h
+++ b/trace2.h
@@ -101,14 +101,8 @@ void trace2_cmd_start_fl(const char *file, int line, const char **argv);
 
 /*
  * Emit an 'exit' event.
- *
- * Write the exit-code that will be passed to exit() or returned
- * from main().
- *
- * Use this prior to actually calling exit().
- * See "#define exit()" in git-compat-util.h
  */
-int trace2_cmd_exit_fl(const char *file, int line, int code);
+void trace2_cmd_exit_fl(const char *file, int line, int code);
 
 #define trace2_cmd_exit(code) (trace2_cmd_exit_fl(__FILE__, __LINE__, (code)))
 

-- 
2.36.1.1100.g16130010d07