banned-die: create header for banning of functions

We have universally-banned functions listed in banned.h since
c8af66ab8a (automatically ban strcpy(), 2018-07-26), but some layers of
the code should be more strict than others.

One such example is the trace2 API which runs during atexit() and can
prove to cause die()-handler recursion problems if it calls die().

Create a new banned-die.h header file that will ban some Git methods
that call die(). Include that in all trace2 API implementation files.
This currently only bans die() itself, and that was already not used.

It would be reasonable to name this file trace2/tr2_banned.h to be
specific to the trace2 API, but it seems like such a restriction would
be valuable to put in some other areas of the code, so adding it at the
root of the tree seems like a good long-term approach.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

banned-die.h

@@ -0,0 +1,14 @@
+#ifndef BANNED_DIE_H
+#define BANNED_DIE_H
+
+#include "banned.h"
+
+/*
+ * This header lists functions that must not be used by low-level APIs
+ * because they can cause Git to terminate.
+ */
+
+#undef die
+#define die BANNED(die)
+
+#endif /* BANNED_DIE_H */

trace2.c

@@ -17,6 +17,8 @@
 #include "trace2/tr2_tgt.h"
 #include "trace2/tr2_tls.h"
 #include "trace2/tr2_tmr.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 static int trace2_enabled;
 static int trace2_redact = 1;

trace2/tr2_cfg.c

@@ -7,6 +7,8 @@
 #include "trace2/tr2_cfg.h"
 #include "trace2/tr2_sysenv.h"
 #include "wildmatch.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 static struct string_list tr2_cfg_patterns = STRING_LIST_INIT_DUP;
 static int tr2_cfg_loaded;

trace2/tr2_cmd_name.c

@@ -1,6 +1,8 @@
 #include "git-compat-util.h"
 #include "strbuf.h"
 #include "trace2/tr2_cmd_name.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 #define TR2_ENVVAR_PARENT_NAME "GIT_TRACE2_PARENT_NAME"
 

trace2/tr2_ctr.c

@@ -2,6 +2,8 @@
 #include "trace2/tr2_tgt.h"
 #include "trace2/tr2_tls.h"
 #include "trace2/tr2_ctr.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 /*
  * A global counter block to aggregate values from the partial sums

trace2/tr2_dst.c

@@ -5,6 +5,8 @@
 #include "trace2/tr2_dst.h"
 #include "trace2/tr2_sid.h"
 #include "trace2/tr2_sysenv.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 /*
  * How many attempts we will make at creating an automatically-named trace file.

trace2/tr2_sid.c

@@ -3,6 +3,8 @@
 #include "strbuf.h"
 #include "trace2/tr2_tbuf.h"
 #include "trace2/tr2_sid.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 #define TR2_ENVVAR_PARENT_SID "GIT_TRACE2_PARENT_SID"
 

trace2/tr2_sysenv.c

@@ -4,6 +4,8 @@
 #include "config.h"
 #include "dir.h"
 #include "tr2_sysenv.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 /*
  * Each entry represents a trace2 setting.

trace2/tr2_tbuf.c

@@ -1,5 +1,7 @@
 #include "git-compat-util.h"
 #include "tr2_tbuf.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 void tr2_tbuf_local_time(struct tr2_tbuf *tb)
 {

trace2/tr2_tgt_event.c

@@ -13,6 +13,8 @@
 #include "trace2/tr2_tgt.h"
 #include "trace2/tr2_tls.h"
 #include "trace2/tr2_tmr.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 static struct tr2_dst tr2dst_event = {
 	.sysenv_var = TR2_SYSENV_EVENT,

trace2/tr2_tgt_normal.c

@@ -11,6 +11,8 @@
 #include "trace2/tr2_tgt.h"
 #include "trace2/tr2_tls.h"
 #include "trace2/tr2_tmr.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 static struct tr2_dst tr2dst_normal = {
 	.sysenv_var = TR2_SYSENV_NORMAL,

trace2/tr2_tgt_perf.c

@@ -14,6 +14,8 @@
 #include "trace2/tr2_tgt.h"
 #include "trace2/tr2_tls.h"
 #include "trace2/tr2_tmr.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 static struct tr2_dst tr2dst_perf = {
 	.sysenv_var = TR2_SYSENV_PERF,

trace2/tr2_tls.c

@@ -3,6 +3,8 @@
 #include "thread-utils.h"
 #include "trace.h"
 #include "trace2/tr2_tls.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 /*
  * Initialize size of the thread stack for nested regions.

trace2/tr2_tmr.c

@@ -3,6 +3,8 @@
 #include "trace2/tr2_tls.h"
 #include "trace2/tr2_tmr.h"
 #include "trace.h"
+/* banned-die must be last. */
+#include "banned-die.h"
 
 #define MY_MAX(a, b) ((a) > (b) ? (a) : (b))
 #define MY_MIN(a, b) ((a) < (b) ? (a) : (b))