0001-BEAM-embed-erlexec-and-EPMD.patch

BEAM: embed erlexec and EPMD

In order to prevent erlexec from execv()-ing or spawning a separate process
to run run BEAM or EPMD, the functionalites of erlexec are now embedded in
BEAM, so that if the BEAM executable file (or a symbolic link to it) is
named "erlexec", BEAM accepts erlexec's command line options. In addition,
EPMD is run as a separate thread instead of as a separate process.

diff -upr otp_orig/erts/emulator/Makefile.in otp/erts/emulator/Makefile.in
--- otp_orig/erts/emulator/Makefile.in	2020-05-13 10:47:33.000000000 +0200
+++ otp/erts/emulator/Makefile.in	2020-05-24 19:42:03.192928031 +0200
@@ -361,6 +361,9 @@ ifeq ($(TARGET),win32)
 LIBS    += -L$(ERL_TOP)/erts/emulator/pcre/obj/$(TARGET)/$(TYPE) -lepcre
 else
 LIBS    += $(ERL_TOP)/erts/emulator/pcre/obj/$(TARGET)/$(TYPE)/$(LIB_PREFIX)epcre$(LIB_SUFFIX)
+ERLEXEC_DIR = $(ERL_TOP)/erts/etc/common
+EPMD_DIR = $(ERL_TOP)/erts/epmd
+include $(EPMD_DIR)/epmd.mk
 endif
 
 EPCRE_LIB = $(ERL_TOP)/erts/emulator/pcre/obj/$(TARGET)/$(TYPE)/$(LIB_PREFIX)epcre$(LIB_SUFFIX)
@@ -741,6 +744,17 @@ $(OBJDIR)/dll_sys.o: sys/$(ERLANG_OSTYPE
 $(OBJDIR)/beams.$(RES_EXT): $(TARGET)/beams.rc
 	$(V_RC) -o $@  -I$(ERL_TOP)/erts/etc/win32 $(TARGET)/beams.rc
 
+else
+
+$(OBJDIR)/erlexec.o: $(ERLEXEC_DIR)/erlexec.c
+	$(V_CC) $(CFLAGS) -DRUN_FROM_EMU -DOTP_SYSTEM_VERSION=\"$(SYSTEM_VSN)\" $(INCLUDES) -c $< -o $@
+$(OBJDIR)/epmd.o: $(EPMD_DIR)/src/epmd.c
+	$(V_CC) $(CFLAGS) -DDONT_USE_MAIN -DEPMD_PORT_NO=$(EPMD_PORT_NO) $(INCLUDES) -c $< -o $@
+$(OBJDIR)/epmd_cli.o: $(EPMD_DIR)/src/epmd_cli.c
+	$(V_CC) $(CFLAGS) $(INCLUDES) -c $< -o $@
+$(OBJDIR)/epmd_srv.o: $(EPMD_DIR)/src/epmd_srv.c
+	$(V_CC) $(CFLAGS) -DDONT_USE_MAIN $(INCLUDES) -c $< -o $@
+
 endif
 
 # We disable the implicit rule of .S -> .o so that the verbose asm
@@ -979,6 +993,10 @@ OS_OBJS = \
 
 else
 OS_OBJS = \
+	$(OBJDIR)/erlexec.o \
+	$(OBJDIR)/epmd.o \
+	$(OBJDIR)/epmd_cli.o \
+	$(OBJDIR)/epmd_srv.o \
 	$(OBJDIR)/sys.o \
 	$(OBJDIR)/sys_drivers.o \
 	$(OBJDIR)/sys_env.o \
diff -upr otp_orig/erts/emulator/sys/unix/erl_main.c otp/erts/emulator/sys/unix/erl_main.c
--- otp_orig/erts/emulator/sys/unix/erl_main.c	2020-05-13 10:47:33.000000000 +0200
+++ otp/erts/emulator/sys/unix/erl_main.c	2020-05-24 16:17:56.295100864 +0200
@@ -27,6 +27,17 @@
 int
 main(int argc, char **argv)
 {
+    char *prog_name = rindex(argv[0], '/');
+
+    if (prog_name)
+        prog_name++;
+    else
+        prog_name = argv[0];
+    if (!strcmp(prog_name, "erlexec")) {
+        extern int erlexec_main(int argc, char **argv);
+
+        return erlexec_main(argc, argv);
+    }
     erl_start(argc, argv);
     return 0;
 }
diff -upr otp_orig/erts/etc/common/erlexec.c otp/erts/etc/common/erlexec.c
--- otp_orig/erts/etc/common/erlexec.c	2020-05-13 10:47:33.000000000 +0200
+++ otp/erts/etc/common/erlexec.c	2020-05-26 16:03:12.906863498 +0200
@@ -25,6 +25,10 @@
 
 #include "etc_common.h"
 
+#if defined(RUN_FROM_EMU)
+#  include "global.h"
+#endif
+
 #include "erl_driver.h"
 #include "erl_misc_utils.h"
 
@@ -227,6 +231,9 @@ int start_emulator(char* emu, char*start
 #endif
 
 
+#if defined(RUN_FROM_EMU)
+int erlexec_main(int argc, char **argv);
+#endif
 
 /*
  * Variables.
@@ -411,6 +418,8 @@ static void add_boot_config(void)
 
 #ifdef __WIN32__
 __declspec(dllexport) int win_erlexec(int argc, char **argv, HANDLE module, int windowed)
+#elif defined(RUN_FROM_EMU)
+int erlexec_main(int argc, char **argv)
 #else
 int main(int argc, char **argv)
 #endif
@@ -451,7 +460,7 @@ int main(int argc, char **argv)
 	goto skip_arg_massage;
     }
     free_env_val(s);
-#else
+#elif !defined(RUN_FROM_EMU)
     int reset_cerl_detached = 0;
 
     s = get_env("CERL_DETACHED_PROG");
@@ -721,16 +730,6 @@ int main(int argc, char **argv)
 			add_Eargs("-B");
 			haltAfterwards = 1;
 			i = argc; /* Skip rest of command line */
-		    } else if (strcmp(argv[i], "-man") == 0) {
-#if defined(__WIN32__)
-			error("-man not supported on Windows");
-#else
-			argv[i] = "man";
-			erts_snprintf(tmpStr, sizeof(tmpStr), "%s/man", rootdir);
-			set_env("MANPATH", tmpStr);
-			execvp("man", argv+i);
-			error("Could not execute the 'man' command.");
-#endif
 		    } else
 			add_arg(argv[i]);
 		    break;
@@ -1132,6 +1131,10 @@ int main(int argc, char **argv)
 
 #else
 
+#if defined(RUN_FROM_EMU)
+    erl_start(EargsCnt, Eargsp);
+    return 0;
+#else
  skip_arg_massage:
     if (start_detached) {
 	int status = fork();
@@ -1184,6 +1187,7 @@ int main(int argc, char **argv)
     }
     return 1;
 #endif
+#endif
 }
 
 
@@ -1196,7 +1200,7 @@ usage_aux(void)
 #ifdef __WIN32__
 	  "[-start_erl [datafile]] "
 #endif
-	  "[-make] [-man [manopts] MANPAGE] [-x] [-emu_args] [-start_epmd BOOLEAN] "
+	  "[-make] [-x] [-emu_args] [-start_epmd BOOLEAN] "
 	  "[-args_file FILENAME] [+A THREADS] [+a SIZE] [+B[c|d|i]] [+c [BOOLEAN]] "
 	  "[+C MODE] [+h HEAP_SIZE_OPTION] [+K BOOLEAN] "
 	  "[+l] [+M<SUBSWITCH> <ARGUMENT>] [+P MAX_PROCS] [+Q MAX_PORTS] "
@@ -1233,9 +1237,31 @@ usage_format(char *format, ...)
     usage_aux();
 }
 
+#if defined(RUN_FROM_EMU)
+static void *epmd_thread(void *arg)
+{
+    extern int epmd(int argc, char **argv);
+    char *argv[] = {
+            "epmd"
+    };
+    epmd(1, argv);
+    return NULL;
+}
+#endif
+
 void
 start_epmd(char *epmd)
 {
+#if defined(RUN_FROM_EMU)
+    pthread_t thread;
+    int result;
+
+    result = pthread_create(&thread, NULL, epmd_thread, NULL);
+    if (result) {
+      fprintf(stderr, "Error spawning epmd (error %d)\n", result);
+      exit(1);
+    }
+#else
     char  epmd_cmd[MAXPATHLEN+100];
 #ifdef __WIN32__
     char* arg1 = NULL;
@@ -1278,6 +1304,7 @@ start_epmd(char *epmd)
       fprintf(stderr, "Error spawning %s (error %d)\n", epmd_cmd,errno);
       exit(1);
     }
+#endif
 }
 
 static void
diff -upr otp_orig/make/install_bin otp/make/install_bin
--- otp_orig/make/install_bin	2020-05-13 10:47:34.000000000 +0200
+++ otp/make/install_bin	2020-05-26 15:47:43.274844730 +0200
@@ -698,6 +698,8 @@ for file in "$@"; do
     }
 done
 
+mv $erlang_bindir/../erts-11.0/bin/beam.smp $erlang_bindir/../erts-11.0/bin/erlexec
+
 test "$tst" = "" || echo "{ok,{$paths,\"$iprfx$bindir\",\"$src_dir\"}}." > $tst
 
 exit 0 # Done