erts: Add env variable ERL_CRASH_DUMP_BYTES

to limit crash dump size

5 files changed, 84 insertions, 3 deletions

diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index f62d3fb170..bd88016ff0 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -1533,6 +1533,15 @@
           </item>
         </taglist>
       </item>
+      <tag><c><![CDATA[ERL_CRASH_DUMP_BYTES]]></c></tag>
+      <item>
+      <p>This variable sets the maximum size of a crash dump file in bytes.
+        The crash dump will be truncated if this limit is exceeded. If the
+	variable is not set, no size limit is enforced by default. If the
+	variable is set to <c>0</c>, the runtime system does not even attempt
+	to write a crash dump file.</p>
+      <p>Introduced in ERTS 8.1.2 (Erlang/OTP 19.2).</p>
+      </item>
       <tag><marker id="ERL_AFLAGS"/><c><![CDATA[ERL_AFLAGS]]></c></tag>
       <item>
         <p>The content of this variable is added to the beginning of the
diff --git a/erts/emulator/beam/break.c b/erts/emulator/beam/break.c
index 2e8a384dec..33433df68a 100644
--- a/erts/emulator/beam/break.c
+++ b/erts/emulator/beam/break.c
@@ -661,6 +661,26 @@ bin_check(void)
 
 #endif
 
+static Sint64 crash_dump_limit = ERTS_SINT64_MAX;
+static Sint64 crash_dump_written = 0;
+
+static int crash_dump_limited_writer(void* vfdp, char* buf, size_t len)
+{
+    const char stop_msg[] = "\n=abort: CRASH DUMP SIZE LIMIT REACHED\n";
+
+    crash_dump_written += len;
+    if (crash_dump_written <= crash_dump_limit) {
+        return erts_write_fd(vfdp, buf, len);
+    }
+
+    len -= (crash_dump_written - crash_dump_limit);
+    erts_write_fd(vfdp, buf, len);
+    erts_write_fd(vfdp, (char*)stop_msg, sizeof(stop_msg)-1);
+
+    /* We assume that crash dump was called from erts_exit_vv() */
+    erts_exit_epilogue();
+}
+
 /* XXX THIS SHOULD BE IN SYSTEM !!!! */
 void
 erl_crash_dump_v(char *file, int line, char* fmt, va_list args)
@@ -760,6 +780,21 @@ erl_crash_dump_v(char *file, int line, char* fmt, va_list args)
 	return;
     }
 
+    crash_dump_limit = ERTS_SINT64_MAX;
+    envsz = sizeof(env);
+    if (erts_sys_getenv__("ERL_CRASH_DUMP_BYTES", env, &envsz) == 0) {
+        Sint64 limit;
+        char* endptr;
+        errno = 0;
+        limit = ErtsStrToSint64(env, &endptr, 10);
+        if (errno == 0 && limit >= 0 && endptr != env && *endptr == 0) {
+            if (limit == 0)
+                return;
+            crash_dump_limit = limit;
+            to = &crash_dump_limited_writer;
+        }
+    }
+
     if (erts_sys_getenv__("ERL_CRASH_DUMP",&dumpnamebuf[0],&dumpnamebufsize) != 0)
 	dumpname = "erl_crash.dump";
     else
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index 781bf024dd..362239f765 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -2374,6 +2374,8 @@ system_cleanup(int flush_async)
     erts_exit_flush_async();
 }
 
+static int erts_exit_code;
+
 static __decl_noreturn void __noreturn
 erts_exit_vv(int n, int flush_async, char *fmt, va_list args1, va_list args2)
 {
@@ -2385,12 +2387,21 @@ erts_exit_vv(int n, int flush_async, char *fmt, va_list args1, va_list args2)
     if (fmt != NULL && *fmt != '\0')
 	erl_error(fmt, args2);	/* Print error message. */
 
-    /* Produce an Erlang core dump if error */
+    erts_exit_code = n;
+
+    /* Produce an Erlang crash dump if error */
     if (((n == ERTS_ERROR_EXIT && erts_no_crash_dump == 0) || n == ERTS_DUMP_EXIT)
 	&& erts_initialized) {
 	erl_crash_dump_v((char*) NULL, 0, fmt, args1);
     }
 
+    erts_exit_epilogue();
+}
+
+__decl_noreturn void __noreturn erts_exit_epilogue(void)
+{
+    int n = erts_exit_code;
+
     sys_tty_reset(n);
 
     if (n == ERTS_INTR_EXIT)
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 244e5edeb6..d6df85034c 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -1079,6 +1079,7 @@ double erts_get_positive_zero_float(void);
 
 /* config.c */
 
+__decl_noreturn void __noreturn erts_exit_epilogue(void);
 __decl_noreturn void __noreturn erts_exit(int n, char*, ...);
 __decl_noreturn void __noreturn erts_flush_async_exit(int n, char*, ...);
 void erl_error(char*, va_list);
diff --git a/erts/emulator/test/bif_SUITE.erl b/erts/emulator/test/bif_SUITE.erl
index d31399e4af..b8d89126fe 100644
--- a/erts/emulator/test/bif_SUITE.erl
+++ b/erts/emulator/test/bif_SUITE.erl
@@ -31,6 +31,7 @@
 	 t_list_to_existing_atom/1,os_env/1,otp_7526/1,
 	 binary_to_atom/1,binary_to_existing_atom/1,
 	 atom_to_binary/1,min_max/1, erlang_halt/1,
+         erl_crash_dump_bytes/1,
 	 is_builtin/1]).
 
 suite() ->
@@ -43,6 +44,7 @@ all() ->
      t_list_to_existing_atom, os_env, otp_7526,
      display,
      atom_to_binary, binary_to_atom, binary_to_existing_atom,
+     erl_crash_dump_bytes,
      min_max, erlang_halt, is_builtin].
 
 %% Uses erlang:display to test that erts_printf does not do deep recursion
@@ -664,7 +666,7 @@ erlang_halt(Config) when is_list(Config) ->
                      [available_internal_state, true]),
     {badrpc,nodedown} = rpc:call(N4, erts_debug, set_internal_state,
                                  [broken_halt, "Validate correct crash dump"]),
-    ok = wait_until_stable_size(CrashDump,-1),
+    {ok,_} = wait_until_stable_size(CrashDump,-1),
     {ok, Bin} = file:read_file(CrashDump),
     case {string:str(binary_to_list(Bin),"\n=end\n"),
           string:str(binary_to_list(Bin),"\r\n=end\r\n")} of
@@ -681,11 +683,34 @@ wait_until_stable_size(File,PrevSz) ->
             wait_until_stable_size(File,PrevSz-1);
         {ok,#file_info{size = PrevSz }} when PrevSz /= -1 ->
             io:format("Crashdump file size was: ~p (~s)~n",[PrevSz,File]),
-            ok;
+            {ok,PrevSz};
         {ok,#file_info{size = NewSz }} ->
             wait_until_stable_size(File,NewSz)
     end.
 
+% Test erlang:halt with ERL_CRASH_DUMP_BYTES
+erl_crash_dump_bytes(Config) when is_list(Config) ->
+    Bytes = 1000,
+    CrashDump = do_limited_crash_dump(Config, Bytes),
+    {ok,ActualBytes} = wait_until_stable_size(CrashDump,-1),
+    true = ActualBytes < (Bytes + 100),
+
+    NoDump = do_limited_crash_dump(Config,0),
+    {error,enoent} = wait_until_stable_size(NoDump,-8),
+    ok.
+
+do_limited_crash_dump(Config, Bytes) ->
+    H = hostname(),
+    {ok,N} = slave:start(H, halt_node),
+    BytesStr = integer_to_list(Bytes),
+    CrashDump = filename:join(proplists:get_value(priv_dir,Config),
+                              "erl_crash." ++ BytesStr ++ ".dump"),
+    true = rpc:call(N, os, putenv, ["ERL_CRASH_DUMP",CrashDump]),
+    true = rpc:call(N, os, putenv, ["ERL_CRASH_DUMP_BYTES",BytesStr]),
+    {badrpc,nodedown} = rpc:call(N, erlang, halt, ["Testing ERL_CRASH_DUMP_BYTES"]),
+    CrashDump.
+
+
 is_builtin(_Config) ->
     Exp0 = [{M,F,A} || {M,_} <- code:all_loaded(),
 		       {F,A} <- M:module_info(exports)],