Attempt at fixing bug 815 by upgrading bb_spawn() so that builtins are at

the start of the path.  (This should be under the same config option as
the standalone shell, but right now that's buried in the shell menu.)

Also add the ability to specify CONFIG_BUSYBOX_EXEC_PATH with /proc/self/exe
as an overrideable default.

Config.in

@@ -32,6 +32,7 @@ config CONFIG_NITPICK
 choice
 	prompt "Buffer allocation policy"
 	default CONFIG_FEATURE_BUFFERS_USE_MALLOC
+	depends on CONFIG_NITPICK
 	help
 	  There are 3 ways BusyBox can handle buffer allocations:
 	  - Use malloc. This costs code size for the call to xmalloc.
@@ -75,11 +76,17 @@ config CONFIG_FEATURE_VERBOSE_USAGE
 config CONFIG_FEATURE_COMPRESS_USAGE
 	bool "Store applet usage messages in compressed form"
 	default y
-	depends on CONFIG_SHOW_USAGE
+	depends on CONFIG_SHOW_USAGE && CONFIG_NITPICK
 	help
 	  Store usage messages in compressed form, uncompress them on-the-fly
 	  when <applet> --help is called.
 
+	  If you have a really tiny busybox with few applets enabled (and
+	  bunzip2 isn't one of them), the overhead of the decompressor might
+	  be noticeable.  Also, if you run executables directly from ROM
+	  and have very little memory, this might not be a win.  Otherwise,
+	  you probably want this.
+
 config CONFIG_FEATURE_INSTALLER
 	bool "Support --install [-s] to install applet links at runtime"
 	default n
@@ -99,14 +106,13 @@ config CONFIG_LOCALE_SUPPORT
 config CONFIG_GETOPT_LONG
 	bool "Enable support for --long-options"
 	default n
-	depends on !CONFIG_NO_GETOPT_LONG
 	help
 	  Enable this if you want busybox applets to use the gnu --long-option
 	  style, in addition to single character -a -b -c style options.
 
 config CONFIG_FEATURE_DEVPTS
 	bool "Use the devpts filesystem for Unix98 PTYs"
-	default y if CONFIG_FEATURE_DEVFS
+	default y
 	help
 	  Enable if you want BusyBox to use Unix98 PTY support. If enabled,
 	  busybox will use /dev/ptmx for the master side of the pseudoterminal
@@ -117,6 +123,7 @@ config CONFIG_FEATURE_DEVPTS
 config CONFIG_FEATURE_CLEAN_UP
 	bool "Clean up all memory before exiting (usually not needed)"
 	default n
+	depends on CONFIG_NITPICK
 	help
 	  As a size optimization, busybox normally exits without explicitly
 	  freeing dynamically allocated memory or closing files.  This saves
@@ -201,6 +208,16 @@ config CONFIG_SELINUX
 
 	  Most people will leave this set to 'N'.
 
+config CONFIG_BUSYBOX_EXEC_PATH
+	string "Path to BusyBox executable"
+	default "/proc/self/exe"
+	help
+	  When Busybox applets need to run other busybox applets, BusyBox
+	  sometimes needs to exec() itself.  When the /proc filesystem is
+	  mounted, /proc/self/exe always points to the currently running
+	  executable.  If you haven't got /proc, set this to wherever you
+	  want to run BusyBox from.
+
 endmenu
 
 menu 'Build Options'
@@ -221,7 +238,8 @@ config CONFIG_STATIC
 
 config CONFIG_BUILD_LIBBUSYBOX
 	bool "Build shared libbusybox"
-	default y
+	depends on CONFIG_STANDALONE
+	default n
 	help
 	  Build a shared library libbusybox.so which contains all
 	  libraries used inside busybox.

include/libbb.h

@@ -171,6 +171,7 @@ extern void xstat(const char *filename, struct stat *buf);
 extern int  bb_xsocket(int domain, int type, int protocol);
 extern pid_t bb_spawn(char **argv);
 extern pid_t bb_xspawn(char **argv);
+extern int wait4pid(int pid);
 extern void bb_xdaemon(int nochdir, int noclose);
 extern void bb_xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen);
 extern void bb_xlisten(int s, int backlog);

libbb/xfuncs.c

@@ -9,6 +9,7 @@
 
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
@@ -189,13 +190,14 @@ pid_t bb_spawn(char **argv)
 {
 	static int failed;
 	pid_t pid;
+	void *app = find_applet_by_name(argv[0]);
 
 	// Be nice to nommu machines.
 	failed = 0;
 	pid = vfork();
 	if (pid < 0) return pid;
 	if (!pid) {
-		execvp(*argv, argv);
+		execvp(app ? CONFIG_BUSYBOX_EXEC_PATH : *argv, argv);
 
 		// We're sharing a stack with blocked parent, let parent know we failed
 		// and then exit to unblock parent (but don't run atexit() stuff, which
@@ -216,3 +218,15 @@ pid_t bb_xspawn(char **argv)
 	return pid;
 }
 #endif
+
+#ifdef L_wait4
+int wait4pid(int pid)
+{
+	int status;
+
+	if (pid == -1 || waitpid(pid, &status, 0) == -1) return -1;
+	if (WIFEXITED(status)) return WEXITSTATUS(status);
+	if (WIFSIGNALED(status)) return WTERMSIG(status);
+	return 0;
+}
+#endif	

modutils/modprobe.c

@@ -666,27 +666,8 @@ static int mod_process ( struct mod_list_t *list, int do_insert )
 				printf("%s module %s\n", do_insert?"Loading":"Unloading", list-> m_name );
 			}
 			if (!show_only) {
-				int rc2 = 0;
-				int status;
-				switch (fork()) {
-				case -1:
-					rc2 = 1;
-					break;
-				case 0: //child
-					execvp(argv[0], argv);
-					bb_perror_msg_and_die("exec of %s", argv[0]);
-					/* NOTREACHED */
-				default:
-					if (wait(&status) == -1) {
-						rc2 = 1;
-						break;
-					}
-					if (WIFEXITED(status))
-						rc2 = WEXITSTATUS(status);
-					if (WIFSIGNALED(status))
-						rc2 = WTERMSIG(status);
-					break;
-				}
+				int rc2 = wait4pid(bb_spawn(argv));
+				
 				if (do_insert) {
 					rc = rc2; /* only last module matters */
 				}