panic_coredump option. Bug 2892

5 files changed, 40 insertions, 8 deletions

diff --git a/src/src/exim.c b/src/src/exim.c
index 1a4b44945..6fde16a9c 100644
--- a/src/src/exim.c
+++ b/src/src/exim.c
@@ -17,6 +17,11 @@ Also a few functions that don't naturally fit elsewhere. */
 # include <gnu/libc-version.h>
 #endif
 
+#ifndef _TIME_H
+# include <time.h>
+#endif
+#include <execinfo.h>	/*XXX maybe glibc-only? */
+
 #ifdef USE_GNUTLS
 # include <gnutls/gnutls.h>
 # if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP)
@@ -24,10 +29,6 @@ Also a few functions that don't naturally fit elsewhere. */
 # endif
 #endif
 
-#ifndef _TIME_H
-# include <time.h>
-#endif
-
 extern void init_lookup_list(void);
 
 
@@ -261,6 +262,29 @@ exit(1);
 *            Handler for SIGSEGV               *
 ***********************************************/
 
+#define STACKDUMP_MAX 24
+void
+stackdump(ucontext_t * ucontext)
+{
+void * buf[STACKDUMP_MAX];
+char ** ss;
+int nptrs = backtrace(buf, STACKDUMP_MAX);
+
+log_write(0, LOG_MAIN|LOG_PANIC, "backtrace\n");
+log_write(0, LOG_MAIN|LOG_PANIC, "---\n");
+if ((ss = backtrace_symbols(buf, nptrs)))
+  {
+  for (int i = 0; i < nptrs; i++)
+    log_write(0, LOG_MAIN|LOG_PANIC, "\t%s\n", ss[i]);
+  free(ss);
+  }
+else
+  log_write(0, LOG_MAIN|LOG_PANIC, "backtrace_symbols: %s\n", strerror(errno));
+log_write(0, LOG_MAIN|LOG_PANIC, "---\n");
+}
+#undef STACKDUMP_MAX
+
+
 static void
 #ifdef SA_SIGINFO
 segv_handler(int sig, siginfo_t * info, void * uctx)
@@ -281,6 +305,7 @@ else
   log_write(0, LOG_MAIN|LOG_PANIC, "SIGSEGV (maybe attempt to write to immutable memory)");
 if (process_info_len > 0)
   log_write(0, LOG_MAIN|LOG_PANIC, "SIGSEGV (%.*s)", process_info_len, process_info);
+stackdump(uctx);
 signal(SIGSEGV, SIG_DFL);
 kill(getpid(), sig);
 }
@@ -291,6 +316,7 @@ segv_handler(int sig)
 log_write(0, LOG_MAIN|LOG_PANIC, "SIGSEGV (maybe attempt to write to immutable memory)");
 if (process_info_len > 0)
   log_write(0, LOG_MAIN|LOG_PANIC, "SIGSEGV (%.*s)", process_info_len, process_info);
+stackdump();
 signal(SIGSEGV, SIG_DFL);
 kill(getpid(), sig);
 }
diff --git a/src/src/globals.c b/src/src/globals.c
index ff246feb4..70e3f568b 100644
--- a/src/src/globals.c
+++ b/src/src/globals.c
@@ -1207,6 +1207,7 @@ uid_t   originator_uid;
 uschar *override_local_interfaces = NULL;
 uschar *override_pid_file_path = NULL;
 
+BOOL    panic_coredump	       = FALSE;
 pcre2_general_context * pcre_gen_ctx = NULL;
 pcre2_compile_context * pcre_cmp_ctx = NULL;
 pcre2_match_context * pcre_mtc_ctx = NULL;
diff --git a/src/src/globals.h b/src/src/globals.h
index fe099e402..ca5b0ccc9 100644
--- a/src/src/globals.h
+++ b/src/src/globals.h
@@ -792,6 +792,7 @@ extern uid_t   originator_uid;         /* Uid of ditto */
 extern uschar *override_local_interfaces; /* Value of -oX argument */
 extern uschar *override_pid_file_path; /* Value of -oP argument */
 
+extern BOOL    panic_coredump;	       /* SEGV rather than exit, on LOG_PANIC_DIE */
 extern pcre2_general_context * pcre_gen_ctx;	/* pcre memory management */
 extern pcre2_compile_context * pcre_cmp_ctx;
 extern pcre2_match_context *   pcre_mtc_ctx;
diff --git a/src/src/log.c b/src/src/log.c
index 8ca973f2d..a46d523db 100644
--- a/src/src/log.c
+++ b/src/src/log.c
@@ -1278,7 +1278,10 @@ if (flags & LOG_PANIC)
   /* Give up if the DIE flag is set */
 
   if ((flags & LOG_PANIC_DIE) != LOG_PANIC)
-    die(NULL, US"Unexpected failure, please try later");
+    if (panic_coredump)
+      kill(getpid(), SIGSEGV);	/* deliberate trap */
+    else
+      die(NULL, US"Unexpected failure, please try later");
   }
 }
 
diff --git a/src/src/readconf.c b/src/src/readconf.c
index 06bc50fd8..c74b70b55 100644
--- a/src/src/readconf.c
+++ b/src/src/readconf.c
@@ -243,6 +243,7 @@ static optionlist optionlist_config[] = {
 #ifdef LOOKUP_ORACLE
   { "oracle_servers",           opt_stringptr,   {&oracle_servers} },
 #endif
+  { "panic_coredump",           opt_bool,        {&panic_coredump} },
   { "percent_hack_domains",     opt_stringptr,   {&percent_hack_domains} },
 #ifdef EXIM_PERL
   { "perl_at_start",            opt_bool,        {&opt_perl_at_start} },
@@ -2667,8 +2668,8 @@ switch(ol->type & opt_mask)
     break;
 
   case opt_bit:
-    printf("%s%s\n", ((*((int *)value)) & (1 << ((ol->type >> 16) & 31)))?
-      "" : "no_", name);
+    printf("%s%s\n", (*((int *)value)) & (1 << ((ol->type >> 16) & 31))
+      ? "" : "no_", name);
     break;
 
   case opt_expand_bool:
@@ -2693,7 +2694,7 @@ switch(ol->type & opt_mask)
   case opt_bool:
   case opt_bool_verify:
   case opt_bool_set:
-    printf("%s%s\n", (*((BOOL *)value))? "" : "no_", name);
+    printf("%s%s\n", *((BOOL *)value) ? "" : "no_", name);
     break;
 
   case opt_func: