Move applets/applet.c into libbb, allows to get rid of --whole-archive

(smaller code). Tested in static and shared mode.

4 files changed, 566 insertions, 548 deletions

diff --git a/applets/applets.c b/applets/applets.c
index 3b4f395c9..bbf150c79 100644
--- a/applets/applets.c
+++ b/applets/applets.c
@@ -1,21 +1,15 @@
 /* vi: set sw=4 ts=4: */
 /*
- * Utility routines.
+ * Stub for linking busybox binary against libbusybox.
  *
- * Copyright (C) tons of folks.  Tracking down who wrote what
- * isn't something I'm going to worry about...  If you wrote something
- * here, please feel free to acknowledge your work.
+ * Copyright (C) 2007 Denis Vlasenko
  *
- * Based in part on code from sash, Copyright (c) 1999 by David I. Bell
- * Permission has been granted to redistribute this code under the GPL.
- *
- * Licensed under GPLv2 or later, see file License in this tarball for details.
+ * Licensed under GPLv2, see file License in this tarball for details.
  */
 
 #include <assert.h>
 #include "busybox.h"
 
-
 /* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */
 #if ENABLE_STATIC && defined(__GLIBC__) && !defined(__UCLIBC__)
 #warning Static linking against glibc produces buggy executables
@@ -27,532 +21,9 @@
 #error Aborting compilation.
 #endif
 
-
-const char *applet_name;
-#if !BB_MMU
-bool re_execed;
-#endif
-
-USE_FEATURE_SUID(static uid_t ruid;)  /* real uid */
-
-#if ENABLE_FEATURE_SUID_CONFIG
-
-/* applets[] is const, so we have to define this "override" structure */
-static struct BB_suid_config {
-	const struct bb_applet *m_applet;
-	uid_t m_uid;
-	gid_t m_gid;
-	mode_t m_mode;
-	struct BB_suid_config *m_next;
-} *suid_config;
-
-static bool suid_cfg_readable;
-
-/* check if u is member of group g */
-static int ingroup(uid_t u, gid_t g)
-{
-	struct group *grp = getgrgid(g);
-
-	if (grp) {
-		char **mem;
-
-		for (mem = grp->gr_mem; *mem; mem++) {
-			struct passwd *pwd = getpwnam(*mem);
-
-			if (pwd && (pwd->pw_uid == u))
-				return 1;
-		}
-	}
-	return 0;
-}
-
-/* This should probably be a libbb routine.  In that case,
- * I'd probably rename it to something like bb_trimmed_slice.
- */
-static char *get_trimmed_slice(char *s, char *e)
-{
-	/* First, consider the value at e to be nul and back up until we
-	 * reach a non-space char.  Set the char after that (possibly at
-	 * the original e) to nul. */
-	while (e-- > s) {
-		if (!isspace(*e)) {
-			break;
-		}
-	}
-	e[1] = '\0';
-
-	/* Next, advance past all leading space and return a ptr to the
-	 * first non-space char; possibly the terminating nul. */
-	return skip_whitespace(s);
-}
-
-/* Don't depend on the tools to combine strings. */
-static const char config_file[] ALIGN1 = "/etc/busybox.conf";
-
-/* We don't supply a value for the nul, so an index adjustment is
- * necessary below.  Also, we use unsigned short here to save some
- * space even though these are really mode_t values. */
-static const unsigned short mode_mask[] ALIGN2 = {
-	/*  SST     sst                 xxx         --- */
-	S_ISUID,    S_ISUID|S_IXUSR,    S_IXUSR,    0,	/* user */
-	S_ISGID,    S_ISGID|S_IXGRP,    S_IXGRP,    0,	/* group */
-	0,          S_IXOTH,            S_IXOTH,    0	/* other */
-};
-
-#define parse_error(x)  do { errmsg = x; goto pe_label; } while (0)
-
-static void parse_config_file(void)
-{
-	struct BB_suid_config *sct_head;
-	struct BB_suid_config *sct;
-	const struct bb_applet *applet;
-	FILE *f;
-	const char *errmsg;
-	char *s;
-	char *e;
-	int i;
-	unsigned lc;
-	smallint section;
-	char buffer[256];
-	struct stat st;
-
-	assert(!suid_config); /* Should be set to NULL by bss init. */
-
-	ruid = getuid();
-	if (ruid == 0) /* run by root - don't need to even read config file */
-		return;
-
-	if ((stat(config_file, &st) != 0)       /* No config file? */
-	 || !S_ISREG(st.st_mode)                /* Not a regular file? */
-	 || (st.st_uid != 0)                    /* Not owned by root? */
-	 || (st.st_mode & (S_IWGRP | S_IWOTH))  /* Writable by non-root? */
-	 || !(f = fopen(config_file, "r"))      /* Cannot open? */
-	) {
-		return;
-	}
-
-	suid_cfg_readable = 1;
-	sct_head = NULL;
-	section = lc = 0;
-
-	while (1) {
-		s = buffer;
-
-		if (!fgets(s, sizeof(buffer), f)) { /* Are we done? */
-			if (ferror(f)) {   /* Make sure it wasn't a read error. */
-				parse_error("reading");
-			}
-			fclose(f);
-			suid_config = sct_head;	/* Success, so set the pointer. */
-			return;
-		}
-
-		lc++;					/* Got a (partial) line. */
-
-		/* If a line is too long for our buffer, we consider it an error.
-		 * The following test does mistreat one corner case though.
-		 * If the final line of the file does not end with a newline and
-		 * yet exactly fills the buffer, it will be treated as too long
-		 * even though there isn't really a problem.  But it isn't really
-		 * worth adding code to deal with such an unlikely situation, and
-		 * we do err on the side of caution.  Besides, the line would be
-		 * too long if it did end with a newline. */
-		if (!strchr(s, '\n') && !feof(f)) {
-			parse_error("line too long");
-		}
-
-		/* Trim leading and trailing whitespace, ignoring comments, and
-		 * check if the resulting string is empty. */
-		s = get_trimmed_slice(s, strchrnul(s, '#'));
-		if (!*s) {
-			continue;
-		}
-
-		/* Check for a section header. */
-
-		if (*s == '[') {
-			/* Unlike the old code, we ignore leading and trailing
-			 * whitespace for the section name.  We also require that
-			 * there are no stray characters after the closing bracket. */
-			e = strchr(s, ']');
-			if (!e   /* Missing right bracket? */
-			 || e[1] /* Trailing characters? */
-			 || !*(s = get_trimmed_slice(s+1, e)) /* Missing name? */
-			) {
-				parse_error("section header");
-			}
-			/* Right now we only have one section so just check it.
-			 * If more sections are added in the future, please don't
-			 * resort to cascading ifs with multiple strcasecmp calls.
-			 * That kind of bloated code is all too common.  A loop
-			 * and a string table would be a better choice unless the
-			 * number of sections is very small. */
-			if (strcasecmp(s, "SUID") == 0) {
-				section = 1;
-				continue;
-			}
-			section = -1;	/* Unknown section so set to skip. */
-			continue;
-		}
-
-		/* Process sections. */
-
-		if (section == 1) {		/* SUID */
-			/* Since we trimmed leading and trailing space above, we're
-			 * now looking for strings of the form
-			 *    <key>[::space::]*=[::space::]*<value>
-			 * where both key and value could contain inner whitespace. */
-
-			/* First get the key (an applet name in our case). */
-			e = strchr(s, '=');
-			if (e) {
-				s = get_trimmed_slice(s, e);
-			}
-			if (!e || !*s) {	/* Missing '=' or empty key. */
-				parse_error("keyword");
-			}
-
-			/* Ok, we have an applet name.  Process the rhs if this
-			 * applet is currently built in and ignore it otherwise.
-			 * Note: this can hide config file bugs which only pop
-			 * up when the busybox configuration is changed. */
-			applet = find_applet_by_name(s);
-			if (applet) {
-				/* Note: We currently don't check for duplicates!
-				 * The last config line for each applet will be the
-				 * one used since we insert at the head of the list.
-				 * I suppose this could be considered a feature. */
-				sct = xmalloc(sizeof(struct BB_suid_config));
-				sct->m_applet = applet;
-				sct->m_mode = 0;
-				sct->m_next = sct_head;
-				sct_head = sct;
-
-				/* Get the specified mode. */
-
-				e = skip_whitespace(e+1);
-
-				for (i = 0; i < 3; i++) {
-					/* There are 4 chars + 1 nul for each of user/group/other. */
-					static const char mode_chars[] ALIGN1 = "Ssx-\0" "Ssx-\0" "Ttx-";
-
-					const char *q;
-					q = strchrnul(mode_chars + 5*i, *e++);
-					if (!*q) {
-						parse_error("mode");
-					}
-					/* Adjust by -i to account for nul. */
-					sct->m_mode |= mode_mask[(q - mode_chars) - i];
-				}
-
-				/* Now get the the user/group info. */
-
-				s = skip_whitespace(e);
-
-				/* Note: we require whitespace between the mode and the
-				 * user/group info. */
-				if ((s == e) || !(e = strchr(s, '.'))) {
-					parse_error("<uid>.<gid>");
-				}
-				*e++ = '\0';
-
-				/* We can't use get_ug_id here since it would exit()
-				 * if a uid or gid was not found.  Oh well... */
-				sct->m_uid = bb_strtoul(s, NULL, 10);
-				if (errno) {
-					struct passwd *pwd = getpwnam(s);
-					if (!pwd) {
-						parse_error("user");
-					}
-					sct->m_uid = pwd->pw_uid;
-				}
-
-				sct->m_gid = bb_strtoul(e, NULL, 10);
-				if (errno) {
-					struct group *grp;
-					grp = getgrnam(e);
-					if (!grp) {
-						parse_error("group");
-					}
-					sct->m_gid = grp->gr_gid;
-				}
-			}
-			continue;
-		}
-
-		/* Unknown sections are ignored. */
-
-		/* Encountering configuration lines prior to seeing a
-		 * section header is treated as an error.  This is how
-		 * the old code worked, but it may not be desirable.
-		 * We may want to simply ignore such lines in case they
-		 * are used in some future version of busybox. */
-		if (!section) {
-			parse_error("keyword outside section");
-		}
-
-	} /* while (1) */
-
- pe_label:
-	fprintf(stderr, "Parse error in %s, line %d: %s\n",
-			config_file, lc, errmsg);
-
-	fclose(f);
-	/* Release any allocated memory before returning. */
-	while (sct_head) {
-		sct = sct_head->m_next;
-		free(sct_head);
-		sct_head = sct;
-	}
-}
-#else
-static inline void parse_config_file(void)
-{
-	USE_FEATURE_SUID(ruid = getuid();)
-}
-#endif /* FEATURE_SUID_CONFIG */
-
-
-#if ENABLE_FEATURE_SUID
-static void check_suid(const struct bb_applet *applet)
-{
-	gid_t rgid;  /* real gid */
-
-	if (ruid == 0) /* set by parse_config_file() */
-		return; /* run by root - no need to check more */
-	rgid = getgid();
-
-#if ENABLE_FEATURE_SUID_CONFIG
-	if (suid_cfg_readable) {
-		uid_t uid;
-		struct BB_suid_config *sct;
-		mode_t m;
-
-		for (sct = suid_config; sct; sct = sct->m_next) {
-			if (sct->m_applet == applet)
-				goto found;
-		}
-		/* default: drop all privileges */
-		xsetgid(rgid);
-		xsetuid(ruid);
-		return;
- found:
-		m = sct->m_mode;
-		if (sct->m_uid == ruid)
-			/* same uid */
-			m >>= 6;
-		else if ((sct->m_gid == rgid) || ingroup(ruid, sct->m_gid))
-			/* same group / in group */
-			m >>= 3;
-
-		if (!(m & S_IXOTH))           /* is x bit not set ? */
-			bb_error_msg_and_die("you have no permission to run this applet!");
-
-		/* _both_ sgid and group_exec have to be set for setegid */
-		if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
-			rgid = sct->m_gid;
-		/* else (no setegid) we will set egid = rgid */
-
-		/* We set effective AND saved ids. If saved-id is not set
-		 * like we do below, seteiud(0) can still later succeed! */
-		if (setresgid(-1, rgid, rgid))
-			bb_perror_msg_and_die("setresgid");
-
-		/* do we have to set effective uid? */
-		uid = ruid;
-		if (sct->m_mode & S_ISUID)
-			uid = sct->m_uid;
-		/* else (no seteuid) we will set euid = ruid */
-
-		if (setresuid(-1, uid, uid))
-			bb_perror_msg_and_die("setresuid");
-		return;
-	}
-#if !ENABLE_FEATURE_SUID_CONFIG_QUIET
-	{
-		static bool onetime = 0;
-
-		if (!onetime) {
-			onetime = 1;
-			fprintf(stderr, "Using fallback suid method\n");
-		}
-	}
-#endif
-#endif
-
-	if (applet->need_suid == _BB_SUID_ALWAYS) {
-		/* Real uid is not 0. If euid isn't 0 too, suid bit
-		 * is most probably not set on our executable */
-		if (geteuid())
-			bb_error_msg_and_die("applet requires root privileges!");
-	} else if (applet->need_suid == _BB_SUID_NEVER) {
-		xsetgid(rgid);  /* drop all privileges */
-		xsetuid(ruid);
-	}
-}
-#else
-#define check_suid(x) ((void)0)
-#endif /* FEATURE_SUID */
-
-
-#if ENABLE_FEATURE_INSTALLER
-/* create (sym)links for each applet */
-static void install_links(const char *busybox, int use_symbolic_links)
-{
-	/* directory table
-	 * this should be consistent w/ the enum,
-	 * busybox.h::bb_install_loc_t, or else... */
-	static const char usr_bin [] ALIGN1 = "/usr/bin";
-	static const char usr_sbin[] ALIGN1 = "/usr/sbin";
-	static const char *const install_dir[] = {
-		&usr_bin [8], /* "", equivalent to "/" for concat_path_file() */
-		&usr_bin [4], /* "/bin" */
-		&usr_sbin[4], /* "/sbin" */
-		usr_bin,
-		usr_sbin
-	};
-
-	int (*lf)(const char *, const char *) = link;
-	char *fpc;
-	int i;
-	int rc;
-
-	if (use_symbolic_links)
-		lf = symlink;
-
-	for (i = 0; applets[i].name != NULL; i++) {
-		fpc = concat_path_file(
-				install_dir[applets[i].install_loc],
-				applets[i].name);
-		rc = lf(busybox, fpc);
-		if (rc != 0 && errno != EEXIST) {
-			bb_simple_perror_msg(fpc);
-		}
-		free(fpc);
-	}
-}
-#else
-#define install_links(x,y) ((void)0)
-#endif /* FEATURE_INSTALLER */
-
-
-/* If we were called as "busybox..." */
-static int busybox_main(char **argv)
-{
-	if (!argv[1]) {
-		/* Called without arguments */
-		const struct bb_applet *a;
-		int col, output_width;
- help:
-		output_width = 80;
-		if (ENABLE_FEATURE_AUTOWIDTH) {
-			/* Obtain the terminal width */
-			get_terminal_width_height(0, &output_width, NULL);
-		}
-		/* leading tab and room to wrap */
-		output_width -= sizeof("start-stop-daemon, ") + 8;
-
-		printf("%s multi-call binary\n", bb_banner); /* reuse const string... */
-		printf("Copyright (C) 1998-2006 Erik Andersen, Rob Landley, and others.\n"
-		       "Licensed under GPLv2. See source distribution for full notice.\n"
-		       "\n"
-		       "Usage: busybox [function] [arguments]...\n"
-		       "   or: [function] [arguments]...\n"
-		       "\n"
-		       "\tBusyBox is a multi-call binary that combines many common Unix\n"
-		       "\tutilities into a single executable.  Most people will create a\n"
-		       "\tlink to busybox for each function they wish to use and BusyBox\n"
-		       "\twill act like whatever it was invoked as!\n"
-		       "\nCurrently defined functions:\n");
-		col = 0;
-		a = applets;
-		while (a->name) {
-			if (col > output_width) {
-				puts(",");
-				col = 0;
-			}
-			col += printf("%s%s", (col ? ", " : "\t"), a->name);
-			a++;
-		}
-		puts("\n");
-		return 0;
-	}
-
-	if (ENABLE_FEATURE_INSTALLER && strcmp(argv[1], "--install") == 0) {
-		const char *busybox;
-		busybox = xmalloc_readlink(bb_busybox_exec_path);
-		if (!busybox)
-			busybox = bb_busybox_exec_path;
-		/* -s makes symlinks */
-		install_links(busybox, argv[2] && strcmp(argv[2], "-s") == 0);
-		return 0;
-	}
-
-	if (strcmp(argv[1], "--help") == 0) {
-		/* "busybox --help [<applet>]" */
-		if (!argv[2])
-			goto help;
-		/* convert to "<applet> --help" */
-		argv[0] = argv[2];
-		argv[2] = NULL;
-	} else {
-		/* "busybox <applet> arg1 arg2 ..." */
-		argv++;
-	}
-	/* We support "busybox /a/path/to/applet args..." too. Allows for
-	 * "#!/bin/busybox"-style wrappers */
-	applet_name = bb_get_last_path_component_nostrip(argv[0]);
-	run_applet_and_exit(applet_name, argv);
-	bb_error_msg_and_die("applet not found");
-}
-
-void run_appletstruct_and_exit(const struct bb_applet *applet, char **argv)
-{
-	int argc = 1;
-
-	while (argv[argc])
-		argc++;
-
-	/* Reinit some shared global data */
-	optind = 1;
-	xfunc_error_retval = EXIT_FAILURE;
-
-	applet_name = applet->name;
-	if (argc == 2 && !strcmp(argv[1], "--help"))
-		bb_show_usage();
-	if (ENABLE_FEATURE_SUID)
-		check_suid(applet);
-	exit(applet->main(argc, argv));
-}
-
-void run_applet_and_exit(const char *name, char **argv)
-{
-	const struct bb_applet *applet = find_applet_by_name(name);
-	if (applet)
-		run_appletstruct_and_exit(applet, argv);
-	if (!strncmp(name, "busybox", 7))
-		exit(busybox_main(argv));
-}
-
-
+#if ENABLE_BUILD_LIBBUSYBOX
 int main(int argc, char **argv)
 {
-	bbox_prepare_main(argv);
-
-#if !BB_MMU
-	/* NOMMU re-exec trick sets high-order bit in first byte of name */
-	if (argv[0][0] & 0x80) {
-		re_execed = 1;
-		argv[0][0] &= 0x7f;
-	}
-#endif
-	applet_name = argv[0];
-	if (applet_name[0] == '-')
-		applet_name++;
-	applet_name = bb_basename(applet_name);
-
-	parse_config_file(); /* ...maybe, if FEATURE_SUID_CONFIG */
-
-	run_applet_and_exit(applet_name, argv);
-	bb_error_msg_and_die("applet not found");
+	return libbusybox_main(argc, argv);
 }
+#endif
diff --git a/include/busybox.h b/include/busybox.h
index 1ab51cf78..1c23b9bb0 100644
--- a/include/busybox.h
+++ b/include/busybox.h
@@ -52,5 +52,8 @@ struct bb_applet {
 extern const struct bb_applet applets[];
 extern const unsigned short NUM_APPLETS;
 void bbox_prepare_main(char **argv);
+#if ENABLE_BUILD_LIBBUSYBOX
+int libbusybox_main(int argc, char **argv);
+#endif
 
 #endif	/* _BB_INTERNAL_H_ */
diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index cfa60a940..7808df501 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -1,11 +1,15 @@
 /* vi: set sw=4 ts=4: */
 /*
- * Support for main() which needs to end up in libbusybox, not busybox,
- * if one builds libbusybox.
+ * Utility routines.
  *
- * Copyright (C) 2007 Denys Vlasenko <vda.linux@googlemail.com>
+ * Copyright (C) tons of folks.  Tracking down who wrote what
+ * isn't something I'm going to worry about...  If you wrote something
+ * here, please feel free to acknowledge your work.
  *
- * Licensed under GPLv2, see file License in this tarball for details.
+ * Based in part on code from sash, Copyright (c) 1999 by David I. Bell
+ * Permission has been granted to redistribute this code under the GPL.
+ *
+ * Licensed under GPLv2 or later, see file License in this tarball for details.
  */
 
 #include <assert.h>
@@ -140,3 +144,544 @@ void bbox_prepare_main(char **argv)
 		bb_show_usage();
 #endif
 }
+
+/* The code below can well be in applets/applets.c, as it is used only
+ * for busybox binary, not "individual" binaries.
+ * However, keeping it here and linking it into libbusybox.so
+ * (together with remaining tiny applets/applets.o)
+ * makes it possible to avoid --whole-archive at link time.
+ * This makes (shared busybox) + libbusybox smaller.
+ * (--gc-sections would be even better....)
+ */
+
+const char *applet_name;
+#if !BB_MMU
+bool re_execed;
+#endif
+
+USE_FEATURE_SUID(static uid_t ruid;)  /* real uid */
+
+#if ENABLE_FEATURE_SUID_CONFIG
+
+/* applets[] is const, so we have to define this "override" structure */
+static struct BB_suid_config {
+	const struct bb_applet *m_applet;
+	uid_t m_uid;
+	gid_t m_gid;
+	mode_t m_mode;
+	struct BB_suid_config *m_next;
+} *suid_config;
+
+static bool suid_cfg_readable;
+
+/* check if u is member of group g */
+static int ingroup(uid_t u, gid_t g)
+{
+	struct group *grp = getgrgid(g);
+
+	if (grp) {
+		char **mem;
+
+		for (mem = grp->gr_mem; *mem; mem++) {
+			struct passwd *pwd = getpwnam(*mem);
+
+			if (pwd && (pwd->pw_uid == u))
+				return 1;
+		}
+	}
+	return 0;
+}
+
+/* This should probably be a libbb routine.  In that case,
+ * I'd probably rename it to something like bb_trimmed_slice.
+ */
+static char *get_trimmed_slice(char *s, char *e)
+{
+	/* First, consider the value at e to be nul and back up until we
+	 * reach a non-space char.  Set the char after that (possibly at
+	 * the original e) to nul. */
+	while (e-- > s) {
+		if (!isspace(*e)) {
+			break;
+		}
+	}
+	e[1] = '\0';
+
+	/* Next, advance past all leading space and return a ptr to the
+	 * first non-space char; possibly the terminating nul. */
+	return skip_whitespace(s);
+}
+
+/* Don't depend on the tools to combine strings. */
+static const char config_file[] ALIGN1 = "/etc/busybox.conf";
+
+/* We don't supply a value for the nul, so an index adjustment is
+ * necessary below.  Also, we use unsigned short here to save some
+ * space even though these are really mode_t values. */
+static const unsigned short mode_mask[] ALIGN2 = {
+	/*  SST     sst                 xxx         --- */
+	S_ISUID,    S_ISUID|S_IXUSR,    S_IXUSR,    0,	/* user */
+	S_ISGID,    S_ISGID|S_IXGRP,    S_IXGRP,    0,	/* group */
+	0,          S_IXOTH,            S_IXOTH,    0	/* other */
+};
+
+#define parse_error(x)  do { errmsg = x; goto pe_label; } while (0)
+
+static void parse_config_file(void)
+{
+	struct BB_suid_config *sct_head;
+	struct BB_suid_config *sct;
+	const struct bb_applet *applet;
+	FILE *f;
+	const char *errmsg;
+	char *s;
+	char *e;
+	int i;
+	unsigned lc;
+	smallint section;
+	char buffer[256];
+	struct stat st;
+
+	assert(!suid_config); /* Should be set to NULL by bss init. */
+
+	ruid = getuid();
+	if (ruid == 0) /* run by root - don't need to even read config file */
+		return;
+
+	if ((stat(config_file, &st) != 0)       /* No config file? */
+	 || !S_ISREG(st.st_mode)                /* Not a regular file? */
+	 || (st.st_uid != 0)                    /* Not owned by root? */
+	 || (st.st_mode & (S_IWGRP | S_IWOTH))  /* Writable by non-root? */
+	 || !(f = fopen(config_file, "r"))      /* Cannot open? */
+	) {
+		return;
+	}
+
+	suid_cfg_readable = 1;
+	sct_head = NULL;
+	section = lc = 0;
+
+	while (1) {
+		s = buffer;
+
+		if (!fgets(s, sizeof(buffer), f)) { /* Are we done? */
+			if (ferror(f)) {   /* Make sure it wasn't a read error. */
+				parse_error("reading");
+			}
+			fclose(f);
+			suid_config = sct_head;	/* Success, so set the pointer. */
+			return;
+		}
+
+		lc++;					/* Got a (partial) line. */
+
+		/* If a line is too long for our buffer, we consider it an error.
+		 * The following test does mistreat one corner case though.
+		 * If the final line of the file does not end with a newline and
+		 * yet exactly fills the buffer, it will be treated as too long
+		 * even though there isn't really a problem.  But it isn't really
+		 * worth adding code to deal with such an unlikely situation, and
+		 * we do err on the side of caution.  Besides, the line would be
+		 * too long if it did end with a newline. */
+		if (!strchr(s, '\n') && !feof(f)) {
+			parse_error("line too long");
+		}
+
+		/* Trim leading and trailing whitespace, ignoring comments, and
+		 * check if the resulting string is empty. */
+		s = get_trimmed_slice(s, strchrnul(s, '#'));
+		if (!*s) {
+			continue;
+		}
+
+		/* Check for a section header. */
+
+		if (*s == '[') {
+			/* Unlike the old code, we ignore leading and trailing
+			 * whitespace for the section name.  We also require that
+			 * there are no stray characters after the closing bracket. */
+			e = strchr(s, ']');
+			if (!e   /* Missing right bracket? */
+			 || e[1] /* Trailing characters? */
+			 || !*(s = get_trimmed_slice(s+1, e)) /* Missing name? */
+			) {
+				parse_error("section header");
+			}
+			/* Right now we only have one section so just check it.
+			 * If more sections are added in the future, please don't
+			 * resort to cascading ifs with multiple strcasecmp calls.
+			 * That kind of bloated code is all too common.  A loop
+			 * and a string table would be a better choice unless the
+			 * number of sections is very small. */
+			if (strcasecmp(s, "SUID") == 0) {
+				section = 1;
+				continue;
+			}
+			section = -1;	/* Unknown section so set to skip. */
+			continue;
+		}
+
+		/* Process sections. */
+
+		if (section == 1) {		/* SUID */
+			/* Since we trimmed leading and trailing space above, we're
+			 * now looking for strings of the form
+			 *    <key>[::space::]*=[::space::]*<value>
+			 * where both key and value could contain inner whitespace. */
+
+			/* First get the key (an applet name in our case). */
+			e = strchr(s, '=');
+			if (e) {
+				s = get_trimmed_slice(s, e);
+			}
+			if (!e || !*s) {	/* Missing '=' or empty key. */
+				parse_error("keyword");
+			}
+
+			/* Ok, we have an applet name.  Process the rhs if this
+			 * applet is currently built in and ignore it otherwise.
+			 * Note: this can hide config file bugs which only pop
+			 * up when the busybox configuration is changed. */
+			applet = find_applet_by_name(s);
+			if (applet) {
+				/* Note: We currently don't check for duplicates!
+				 * The last config line for each applet will be the
+				 * one used since we insert at the head of the list.
+				 * I suppose this could be considered a feature. */
+				sct = xmalloc(sizeof(struct BB_suid_config));
+				sct->m_applet = applet;
+				sct->m_mode = 0;
+				sct->m_next = sct_head;
+				sct_head = sct;
+
+				/* Get the specified mode. */
+
+				e = skip_whitespace(e+1);
+
+				for (i = 0; i < 3; i++) {
+					/* There are 4 chars + 1 nul for each of user/group/other. */
+					static const char mode_chars[] ALIGN1 = "Ssx-\0" "Ssx-\0" "Ttx-";
+
+					const char *q;
+					q = strchrnul(mode_chars + 5*i, *e++);
+					if (!*q) {
+						parse_error("mode");
+					}
+					/* Adjust by -i to account for nul. */
+					sct->m_mode |= mode_mask[(q - mode_chars) - i];
+				}
+
+				/* Now get the the user/group info. */
+
+				s = skip_whitespace(e);
+
+				/* Note: we require whitespace between the mode and the
+				 * user/group info. */
+				if ((s == e) || !(e = strchr(s, '.'))) {
+					parse_error("<uid>.<gid>");
+				}
+				*e++ = '\0';
+
+				/* We can't use get_ug_id here since it would exit()
+				 * if a uid or gid was not found.  Oh well... */
+				sct->m_uid = bb_strtoul(s, NULL, 10);
+				if (errno) {
+					struct passwd *pwd = getpwnam(s);
+					if (!pwd) {
+						parse_error("user");
+					}
+					sct->m_uid = pwd->pw_uid;
+				}
+
+				sct->m_gid = bb_strtoul(e, NULL, 10);
+				if (errno) {
+					struct group *grp;
+					grp = getgrnam(e);
+					if (!grp) {
+						parse_error("group");
+					}
+					sct->m_gid = grp->gr_gid;
+				}
+			}
+			continue;
+		}
+
+		/* Unknown sections are ignored. */
+
+		/* Encountering configuration lines prior to seeing a
+		 * section header is treated as an error.  This is how
+		 * the old code worked, but it may not be desirable.
+		 * We may want to simply ignore such lines in case they
+		 * are used in some future version of busybox. */
+		if (!section) {
+			parse_error("keyword outside section");
+		}
+
+	} /* while (1) */
+
+ pe_label:
+	fprintf(stderr, "Parse error in %s, line %d: %s\n",
+			config_file, lc, errmsg);
+
+	fclose(f);
+	/* Release any allocated memory before returning. */
+	while (sct_head) {
+		sct = sct_head->m_next;
+		free(sct_head);
+		sct_head = sct;
+	}
+}
+#else
+static inline void parse_config_file(void)
+{
+	USE_FEATURE_SUID(ruid = getuid();)
+}
+#endif /* FEATURE_SUID_CONFIG */
+
+
+#if ENABLE_FEATURE_SUID
+static void check_suid(const struct bb_applet *applet)
+{
+	gid_t rgid;  /* real gid */
+
+	if (ruid == 0) /* set by parse_config_file() */
+		return; /* run by root - no need to check more */
+	rgid = getgid();
+
+#if ENABLE_FEATURE_SUID_CONFIG
+	if (suid_cfg_readable) {
+		uid_t uid;
+		struct BB_suid_config *sct;
+		mode_t m;
+
+		for (sct = suid_config; sct; sct = sct->m_next) {
+			if (sct->m_applet == applet)
+				goto found;
+		}
+		/* default: drop all privileges */
+		xsetgid(rgid);
+		xsetuid(ruid);
+		return;
+ found:
+		m = sct->m_mode;
+		if (sct->m_uid == ruid)
+			/* same uid */
+			m >>= 6;
+		else if ((sct->m_gid == rgid) || ingroup(ruid, sct->m_gid))
+			/* same group / in group */
+			m >>= 3;
+
+		if (!(m & S_IXOTH))           /* is x bit not set ? */
+			bb_error_msg_and_die("you have no permission to run this applet!");
+
+		/* _both_ sgid and group_exec have to be set for setegid */
+		if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
+			rgid = sct->m_gid;
+		/* else (no setegid) we will set egid = rgid */
+
+		/* We set effective AND saved ids. If saved-id is not set
+		 * like we do below, seteiud(0) can still later succeed! */
+		if (setresgid(-1, rgid, rgid))
+			bb_perror_msg_and_die("setresgid");
+
+		/* do we have to set effective uid? */
+		uid = ruid;
+		if (sct->m_mode & S_ISUID)
+			uid = sct->m_uid;
+		/* else (no seteuid) we will set euid = ruid */
+
+		if (setresuid(-1, uid, uid))
+			bb_perror_msg_and_die("setresuid");
+		return;
+	}
+#if !ENABLE_FEATURE_SUID_CONFIG_QUIET
+	{
+		static bool onetime = 0;
+
+		if (!onetime) {
+			onetime = 1;
+			fprintf(stderr, "Using fallback suid method\n");
+		}
+	}
+#endif
+#endif
+
+	if (applet->need_suid == _BB_SUID_ALWAYS) {
+		/* Real uid is not 0. If euid isn't 0 too, suid bit
+		 * is most probably not set on our executable */
+		if (geteuid())
+			bb_error_msg_and_die("applet requires root privileges!");
+	} else if (applet->need_suid == _BB_SUID_NEVER) {
+		xsetgid(rgid);  /* drop all privileges */
+		xsetuid(ruid);
+	}
+}
+#else
+#define check_suid(x) ((void)0)
+#endif /* FEATURE_SUID */
+
+
+#if ENABLE_FEATURE_INSTALLER
+/* create (sym)links for each applet */
+static void install_links(const char *busybox, int use_symbolic_links)
+{
+	/* directory table
+	 * this should be consistent w/ the enum,
+	 * busybox.h::bb_install_loc_t, or else... */
+	static const char usr_bin [] ALIGN1 = "/usr/bin";
+	static const char usr_sbin[] ALIGN1 = "/usr/sbin";
+	static const char *const install_dir[] = {
+		&usr_bin [8], /* "", equivalent to "/" for concat_path_file() */
+		&usr_bin [4], /* "/bin" */
+		&usr_sbin[4], /* "/sbin" */
+		usr_bin,
+		usr_sbin
+	};
+
+	int (*lf)(const char *, const char *) = link;
+	char *fpc;
+	int i;
+	int rc;
+
+	if (use_symbolic_links)
+		lf = symlink;
+
+	for (i = 0; applets[i].name != NULL; i++) {
+		fpc = concat_path_file(
+				install_dir[applets[i].install_loc],
+				applets[i].name);
+		rc = lf(busybox, fpc);
+		if (rc != 0 && errno != EEXIST) {
+			bb_simple_perror_msg(fpc);
+		}
+		free(fpc);
+	}
+}
+#else
+#define install_links(x,y) ((void)0)
+#endif /* FEATURE_INSTALLER */
+
+/* If we were called as "busybox..." */
+static int busybox_main(char **argv)
+{
+	if (!argv[1]) {
+		/* Called without arguments */
+		const struct bb_applet *a;
+		int col, output_width;
+ help:
+		output_width = 80;
+		if (ENABLE_FEATURE_AUTOWIDTH) {
+			/* Obtain the terminal width */
+			get_terminal_width_height(0, &output_width, NULL);
+		}
+		/* leading tab and room to wrap */
+		output_width -= sizeof("start-stop-daemon, ") + 8;
+
+		printf("%s multi-call binary\n", bb_banner); /* reuse const string... */
+		printf("Copyright (C) 1998-2006 Erik Andersen, Rob Landley, and others.\n"
+		       "Licensed under GPLv2. See source distribution for full notice.\n"
+		       "\n"
+		       "Usage: busybox [function] [arguments]...\n"
+		       "   or: [function] [arguments]...\n"
+		       "\n"
+		       "\tBusyBox is a multi-call binary that combines many common Unix\n"
+		       "\tutilities into a single executable.  Most people will create a\n"
+		       "\tlink to busybox for each function they wish to use and BusyBox\n"
+		       "\twill act like whatever it was invoked as!\n"
+		       "\nCurrently defined functions:\n");
+		col = 0;
+		a = applets;
+		while (a->name) {
+			if (col > output_width) {
+				puts(",");
+				col = 0;
+			}
+			col += printf("%s%s", (col ? ", " : "\t"), a->name);
+			a++;
+		}
+		puts("\n");
+		return 0;
+	}
+
+	if (ENABLE_FEATURE_INSTALLER && strcmp(argv[1], "--install") == 0) {
+		const char *busybox;
+		busybox = xmalloc_readlink(bb_busybox_exec_path);
+		if (!busybox)
+			busybox = bb_busybox_exec_path;
+		/* -s makes symlinks */
+		install_links(busybox, argv[2] && strcmp(argv[2], "-s") == 0);
+		return 0;
+	}
+
+	if (strcmp(argv[1], "--help") == 0) {
+		/* "busybox --help [<applet>]" */
+		if (!argv[2])
+			goto help;
+		/* convert to "<applet> --help" */
+		argv[0] = argv[2];
+		argv[2] = NULL;
+	} else {
+		/* "busybox <applet> arg1 arg2 ..." */
+		argv++;
+	}
+	/* We support "busybox /a/path/to/applet args..." too. Allows for
+	 * "#!/bin/busybox"-style wrappers */
+	applet_name = bb_get_last_path_component_nostrip(argv[0]);
+	run_applet_and_exit(applet_name, argv);
+	bb_error_msg_and_die("applet not found");
+}
+
+void run_appletstruct_and_exit(const struct bb_applet *applet, char **argv)
+{
+	int argc = 1;
+
+	while (argv[argc])
+		argc++;
+
+	/* Reinit some shared global data */
+	optind = 1;
+	xfunc_error_retval = EXIT_FAILURE;
+
+	applet_name = applet->name;
+	if (argc == 2 && !strcmp(argv[1], "--help"))
+		bb_show_usage();
+	if (ENABLE_FEATURE_SUID)
+		check_suid(applet);
+	exit(applet->main(argc, argv));
+}
+
+void run_applet_and_exit(const char *name, char **argv)
+{
+	const struct bb_applet *applet = find_applet_by_name(name);
+	if (applet)
+		run_appletstruct_and_exit(applet, argv);
+	if (!strncmp(name, "busybox", 7))
+		exit(busybox_main(argv));
+}
+
+
+#if ENABLE_BUILD_LIBBUSYBOX
+int libbusybox_main(int argc, char **argv)
+#else
+int main(int argc, char **argv)
+#endif
+{
+	bbox_prepare_main(argv);
+
+#if !BB_MMU
+	/* NOMMU re-exec trick sets high-order bit in first byte of name */
+	if (argv[0][0] & 0x80) {
+		re_execed = 1;
+		argv[0][0] &= 0x7f;
+	}
+#endif
+	applet_name = argv[0];
+	if (applet_name[0] == '-')
+		applet_name++;
+	applet_name = bb_basename(applet_name);
+
+	parse_config_file(); /* ...maybe, if FEATURE_SUID_CONFIG */
+
+	run_applet_and_exit(applet_name, argv);
+	bb_error_msg_and_die("applet not found");
+}
diff --git a/scripts/trylink b/scripts/trylink
index fc87df032..6292dc659 100755
--- a/scripts/trylink
+++ b/scripts/trylink
@@ -19,18 +19,16 @@ debug=false
 # List of files to link:
 # $l_list                       == --start-group -llib1 -llib2 --end-group
 # --start-group $O_FILES $A_FILES --end-group
-# or for shlib:
-# --start-group --whole-archive $A_FILES --no-whole-archive --end-group
-# otherwise we don't pull in all parts of *.a files. Now we pull in too much.
-# FIXME: make it work without --whole-archive, or better, with --gc-sections.
 #
 # Shared library link:
 # -shared                       self-explanatory
 # -fPIC                         position-independent code
-# -Wl,--enable-new-dtags        ?
-# -Wl,-z,combreloc              ?
-# -Wl,-soname="libbusybox.so.$BB_VER"
-# -static			Not used, but may be useful! manpage:
+# --enable-new-dtags            ?
+# -z,combreloc                  ?
+# -soname="libbusybox.so.$BB_VER"
+# --undefined=libbusybox_main   Seed name to start pulling from
+#                               (otherwise we'll need --whole-archive)
+# -static                       Not used, but may be useful! manpage:
 #                               "... This option can be used with -shared.
 #                               Doing so means that a shared library
 #                               is being created but that all of the library's
@@ -174,9 +172,10 @@ if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
 	    -Wl,--enable-new-dtags \
 	    -Wl,-z,combreloc \
 	    -Wl,-soname="libbusybox.so.$BB_VER" \
+	    -Wl,--undefined=libbusybox_main \
 	    -Wl,--sort-common \
 	    -Wl,--sort-section -Wl,alignment \
-	    -Wl,--start-group -Wl,--whole-archive $A_FILES -Wl,--no-whole-archive -Wl,--end-group \
+	    -Wl,--start-group $A_FILES -Wl,--end-group \
 	    $l_list \
 	    -Wl,--warn-common \
 	    -Wl,-Map -Wl,$EXE.map \