From 604d320f23c42c349f3f44710bcbc05fde7db661 Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Thu, 4 Jul 2013 17:44:23 +0200
Subject: Make emulator arguments available via the system_info BIF

erlang:system_info(emu_args)
---
 erts/emulator/beam/erl_bif_info.c |  3 ++
 erts/emulator/beam/erl_init.c     |  2 +
 erts/emulator/beam/erl_utils.h    |  4 ++
 erts/emulator/beam/utils.c        | 91 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 100 insertions(+)

(limited to 'erts')

diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 74a37f374d..447c1fdf18 100755
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -2646,6 +2646,9 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
 #endif
 	BIF_RET(am_true);
     }
+    else if (ERTS_IS_ATOM_STR("emu_args", BIF_ARG_1)) {
+	BIF_RET(erts_get_emu_args(BIF_P));
+    }
     else if (ERTS_IS_ATOM_STR("dynamic_trace", BIF_ARG_1)) {
 #if defined(USE_DTRACE)
 	DECL_AM(dtrace);
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index 4bae3dfeb4..8d137df7ae 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -637,6 +637,8 @@ early_init(int *argc, char **argv) /*
     char envbuf[21]; /* enough for any 64-bit integer */
     size_t envbufsz;
 
+    erts_save_emu_args(*argc, argv);
+
     erts_sched_compact_load = 1;
     erts_printf_eterm_func = erts_printf_term;
     erts_disable_tolerant_timeofday = 0;
diff --git a/erts/emulator/beam/erl_utils.h b/erts/emulator/beam/erl_utils.h
index a2064bd8a3..79c5105d92 100644
--- a/erts/emulator/beam/erl_utils.h
+++ b/erts/emulator/beam/erl_utils.h
@@ -24,6 +24,8 @@
 #include "erl_smp.h"
 #include "erl_printf.h"
 
+struct process;
+
 typedef struct {
 #ifdef DEBUG
     int smp_api;
@@ -155,6 +157,8 @@ Uint32 block_hash(byte *, unsigned, Uint32);
 Uint32 make_hash2(Eterm);
 Uint32 make_hash(Eterm);
 
+void erts_save_emu_args(int argc, char **argv);
+Eterm erts_get_emu_args(struct process *c_p);
 
 Eterm erts_bld_atom(Uint **hpp, Uint *szp, char *str);
 Eterm erts_bld_uint(Uint **hpp, Uint *szp, Uint ui);
diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index 62caa67ce1..eb1c8f6173 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -3466,6 +3466,97 @@ erts_free_read_env(void *value)
 	erts_free(ERTS_ALC_T_TMP, value);
 }
 
+
+typedef struct {
+    size_t sz;
+    char *ptr;
+} ErtsEmuArg;
+
+typedef struct {
+    int argc;
+    ErtsEmuArg *arg;
+    size_t no_bytes;
+} ErtsEmuArgs;
+
+ErtsEmuArgs saved_emu_args = {0};
+
+void
+erts_save_emu_args(int argc, char **argv)
+{
+#ifdef DEBUG
+    char *end_ptr;
+#endif
+    char *ptr;
+    int i;
+    size_t arg_sz[100];
+    size_t size;
+
+    ASSERT(!saved_emu_args.argc);
+
+    size = sizeof(ErtsEmuArg)*argc;
+    for (i = 0; i < argc; i++) {
+	size_t sz = sys_strlen(argv[i]);
+	if (i < sizeof(arg_sz)/sizeof(arg_sz[0]))
+	    arg_sz[i] = sz;
+	size += sz+1;
+    } 
+    ptr = (char *) malloc(size);
+#ifdef DEBUG
+    end_ptr = ptr + size;
+#endif
+    saved_emu_args.arg = (ErtsEmuArg *) ptr;
+    ptr += sizeof(ErtsEmuArg)*argc;
+    saved_emu_args.argc = argc;
+    saved_emu_args.no_bytes = 0;
+    for (i = 0; i < argc; i++) {
+	size_t sz;
+	if (i < sizeof(arg_sz)/sizeof(arg_sz[0]))
+	    sz = arg_sz[i];
+	else
+	    sz = sys_strlen(argv[i]);
+	saved_emu_args.arg[i].ptr = ptr;
+	saved_emu_args.arg[i].sz = sz;
+	saved_emu_args.no_bytes += sz;
+	ptr += sz+1;
+	sys_strcpy(saved_emu_args.arg[i].ptr, argv[i]);
+    }
+    ASSERT(ptr == end_ptr);
+}
+
+Eterm
+erts_get_emu_args(Process *c_p)
+{
+#ifdef DEBUG
+    Eterm *end_hp;
+#endif
+    int i;
+    Uint hsz;
+    Eterm *hp, res;
+
+    hsz = saved_emu_args.no_bytes*2;
+    hsz += saved_emu_args.argc*2;
+
+    hp = HAlloc(c_p, hsz);
+#ifdef DEBUG
+    end_hp = hp + hsz;
+#endif
+    res = NIL;
+
+    for (i = saved_emu_args.argc-1; i >= 0; i--) {
+	Eterm arg = buf_to_intlist(&hp,
+				   saved_emu_args.arg[i].ptr,
+				   saved_emu_args.arg[i].sz,
+				   NIL);
+	res = CONS(hp, arg, res);
+	hp += 2;
+    }
+
+    ASSERT(hp == end_hp);
+
+    return res;
+}
+
+
 /*
  * To be used to silence unused result warnings, but do not abuse it.
  */
-- 
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