ash: allow shell scripts to be embedded in the binary

To assist in the deployment of shell scripts it may be convenient
to embed them in the BusyBox binary.

'Embed scripts in the binary' takes any files in the directory
'embed', concatenates them with null separators, compresses them
and embeds them in the binary.

When scripts are embedded in the binary, scripts can be run as
'busybox SCRIPT [ARGS]' or by usual (sym)link mechanism.

embed/nologin is provided as an example.

function                                             old     new   delta
packed_scripts                                         -     123    +123
unpack_scripts                                         -      87     +87
ash_main                                            1103    1171     +68
run_applet_and_exit                                   78     128     +50
get_script_content                                     -      32     +32
script_names                                           -      10     +10
expmeta                                              663     659      -4
------------------------------------------------------------------------------
(add/remove: 4/0 grow/shrink: 2/1 up/down: 370/-4)            Total: 366 bytes

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 32 insertions, 1 deletions

diff --git a/shell/ash.c b/shell/ash.c
index dc1a55a6b..25468d796 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -148,6 +148,21 @@
 //config:	you to run the specified command or builtin,
 //config:	even when there is a function with the same name.
 //config:
+//config:config ASH_EMBEDDED_SCRIPTS
+//config:	bool "Embed scripts in the binary"
+//config:	default y
+//config:	depends on ASH || SH_IS_ASH || BASH_IS_ASH
+//config:	help
+//config:	Allow scripts to be compressed and embedded in the BusyBox
+//config:	binary. The scripts should be placed in the 'embed' directory
+//config:	at build time. In standalone shell mode such scripts can be
+//config:	run directly and are subject to tab completion; otherwise they
+//config:	can be run by giving their name as an argument to the shell.
+//config:	For convenience shell aliases are created. The '-L' shell
+//config:	argument lists the names of the scripts. Like applets scripts
+//config:	can be run as 'busybox name ...' or by linking their name to
+//config:	the binary.
+//config:
 //config:endif # ash options
 
 //applet:IF_ASH(APPLET(ash, BB_DIR_BIN, BB_SUID_DROP))
@@ -181,6 +196,11 @@
 #include <sys/times.h>
 #include <sys/utsname.h> /* for setting $HOSTNAME */
 #include "busybox.h" /* for applet_names */
+#if ENABLE_ASH_EMBEDDED_SCRIPTS
+# include "embedded_scripts.h"
+#else
+# define NUM_SCRIPTS 0
+#endif
 
 /* So far, all bash compat is controlled by one config option */
 /* Separate defines document which part of code implements what */
@@ -14021,13 +14041,17 @@ procargs(char **argv)
 	int login_sh;
 
 	xargv = argv;
+#if NUM_SCRIPTS > 0
+	if (minusc)
+		goto setarg0;
+#endif
 	login_sh = xargv[0] && xargv[0][0] == '-';
 	arg0 = xargv[0];
 	/* if (xargv[0]) - mmm, this is always true! */
 		xargv++;
+	argptr = xargv;
 	for (i = 0; i < NOPTS; i++)
 		optlist[i] = 2;
-	argptr = xargv;
 	if (options(/*cmdline:*/ 1, &login_sh)) {
 		/* it already printed err message */
 		raise_exception(EXERROR);
@@ -14130,6 +14154,7 @@ extern int etext();
  */
 int ash_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int ash_main(int argc UNUSED_PARAM, char **argv)
+/* note: 'argc' is used only if embedded scripts are enabled */
 {
 	volatile smallint state;
 	struct jmploc jmploc;
@@ -14183,6 +14208,12 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
 
 	init();
 	setstackmark(&smark);
+
+#if NUM_SCRIPTS > 0
+	if (argc < 0)
+		/* Non-NULL minusc tells procargs that an embedded script is being run */
+		minusc = get_script_content(-argc - 1);
+#endif
 	login_sh = procargs(argv);
 #if DEBUG
 	TRACE(("Shell args: "));