sourse_route_list -> source_route_list
[oweals/busybox.git] / applets / applets.c
index 4af569de305ad482045f9ccc863a3b5071ebed0a..82a7eeea10fdc06f44bf8b3fe1ee24bc47c425e1 100644 (file)
  * isn't something I'm going to worry about...  If you wrote something
  * here, please feel free to acknowledge your work.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
- *
  * 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 <unistd.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+#include <assert.h>
 #include "busybox.h"
 
-#undef APPLET
-#undef APPLET_NOUSAGE
+/* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */
+#if ENABLE_STATIC && defined(__GLIBC__) && !defined(__UCLIBC__)
+#warning Static linking against glibc produces buggy executables
+#warning (glibc does not cope well with ld --gc-sections).
+#warning See sources.redhat.com/bugzilla/show_bug.cgi?id=3400
+#warning Note that glibc is unsuitable for static linking anyway.
+#warning If you still want to do it, remove -Wl,--gc-sections
+#warning from top-level Makefile and remove this warning.
+#endif
+
+
+/* Declare <applet>_main() */
+#define PROTOTYPES
+#include "applets.h"
 #undef PROTOTYPES
+
+#if ENABLE_SHOW_USAGE && !ENABLE_FEATURE_COMPRESS_USAGE
+/* Define usage_messages[] */
+static const char usage_messages[] = ""
+#define MAKE_USAGE
+#include "usage.h"
 #include "applets.h"
+;
+#undef MAKE_USAGE
+#else
+#define usage_messages 0
+#endif /* SHOW_USAGE */
 
-struct BB_applet *applet_using;
+/* Define struct bb_applet applets[] */
+#include "applets.h"
+/* The -1 arises because of the {0,NULL,0,-1} entry. */
+const unsigned short NUM_APPLETS = sizeof(applets) / sizeof(applets[0]) - 1;
 
-/* The -1 arises because of the {0,NULL,0,-1} entry above. */
-const size_t NUM_APPLETS = (sizeof (applets) / sizeof (struct BB_applet) - 1);
 
+const struct bb_applet *current_applet;
+const char *applet_name ATTRIBUTE_EXTERNALLY_VISIBLE;
+#if !BB_MMU
+bool re_execed;
+#endif
 
-#ifdef CONFIG_FEATURE_SUID
 
-static void check_suid (struct BB_applet *app);
 
-#ifdef CONFIG_FEATURE_SUID_CONFIG
+#if ENABLE_FEATURE_SUID_CONFIG
 
-#include <sys/stat.h>
-#include <ctype.h>
-#include "pwd_.h"
-#include "grp_.h"
+/* 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 int parse_config_file (void);
+static bool suid_cfg_readable;
 
-static int config_ok;
+/* check if u is member of group g */
+static int ingroup(uid_t u, gid_t g)
+{
+       struct group *grp = getgrgid(g);
 
-#define CONFIG_FILE "/etc/busybox.conf"
+       if (grp) {
+               char **mem;
 
-/* applets [] is const, so we have to define this "override" structure */
-struct BB_suid_config
-{
-  struct BB_applet *m_applet;
+               for (mem = grp->gr_mem; *mem; mem++) {
+                       struct passwd *pwd = getpwnam(*mem);
 
-  uid_t m_uid;
-  gid_t m_gid;
-  mode_t m_mode;
+                       if (pwd && (pwd->pw_uid == u))
+                               return 1;
+               }
+       }
+       return 0;
+}
 
-  struct BB_suid_config *m_next;
-};
+/* 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';
 
-static struct BB_suid_config *suid_config;
+       /* Next, advance past all leading space and return a ptr to the
+        * first non-space char; possibly the terminating nul. */
+       return skip_whitespace(s);
+}
 
-#endif /* CONFIG_FEATURE_SUID_CONFIG */
+/* Don't depend on the tools to combine strings. */
+static const char config_file[] = "/etc/busybox.conf";
 
-#endif /* CONFIG_FEATURE_SUID */
+/* There are 4 chars + 1 nul for each of user/group/other. */
+static const char mode_chars[] = "Ssx-\0Ssx-\0Ttx-";
 
+/* 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[] = {
+       /*  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)
 
-extern void
-bb_show_usage (void)
+static void parse_config_file(void)
 {
-  const char *format_string;
-  const char *usage_string = usage_messages;
-  int i;
-
-  for (i = applet_using - applets; i > 0;) {
-       if (!*usage_string++) {
-         --i;
+       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. */
+
+       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;
        }
-  }
 
-  format_string = "%s\n\nUsage: %s %s\n\n";
-  if (*usage_string == '\b')
-       format_string = "%s\n\nNo help available.\n\n";
-  fprintf (stderr, format_string, bb_msg_full_version, applet_using->name,
-                  usage_string);
+       suid_cfg_readable = 1;
+       sct_head = NULL;
+       section = lc = 0;
 
-  exit (EXIT_FAILURE);
-}
+       while (1) {
+               s = buffer;
 
-static int
-applet_name_compare (const void *x, const void *y)
-{
-  const char *name = x;
-  const struct BB_applet *applet = y;
+               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;
+               }
 
-  return strcmp (name, applet->name);
-}
+               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");
+               }
 
-extern const size_t NUM_APPLETS;
+               /* 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;
+               }
 
-struct BB_applet *
-find_applet_by_name (const char *name)
-{
-  return bsearch (name, applets, NUM_APPLETS, sizeof (struct BB_applet),
-                                 applet_name_compare);
-}
+               /* 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;
+               }
 
-void
-run_applet_by_name (const char *name, int argc, char **argv)
-{
-  static int recurse_level = 0;
-  extern int been_there_done_that;      /* From busybox.c */
+               /* Process sections. */
 
-#ifdef CONFIG_FEATURE_SUID_CONFIG
-  if (recurse_level == 0)
-       config_ok = parse_config_file ();
-#endif
+               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. */
 
-  recurse_level++;
-  /* Do a binary search to find the applet entry given the name. */
-  if ((applet_using = find_applet_by_name (name)) != NULL) {
-       bb_applet_name = applet_using->name;
-       if (argv[1] && strcmp (argv[1], "--help") == 0) {
-         if (strcmp (applet_using->name, "busybox") == 0) {
-               if (argv[2])
-                 applet_using = find_applet_by_name (argv[2]);
-               else
-                 applet_using = NULL;
-         }
-         if (applet_using)
-               bb_show_usage ();
-         been_there_done_that = 1;
-         busybox_main (0, NULL);
-       }
-#ifdef CONFIG_FEATURE_SUID
-       check_suid (applet_using);
-#endif
+                       /* 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");
+                       }
 
-       exit ((*(applet_using->main)) (argc, argv));
-  }
-  /* Just in case they have renamed busybox - Check argv[1] */
-  if (recurse_level == 1) {
-       run_applet_by_name ("busybox", argc, argv);
-  }
-  recurse_level--;
-}
+                       /* 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++) {
+                                       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. */
 
-#ifdef CONFIG_FEATURE_SUID
+                               s = skip_whitespace(e);
 
-#ifdef CONFIG_FEATURE_SUID_CONFIG
+                               /* 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;
+                               }
 
-/* check if u is member of group g */
-static int
-ingroup (uid_t u, gid_t g)
-{
-  struct group *grp = getgrgid (g);
+                               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;
+               }
 
-  if (grp) {
-       char **mem;
+               /* 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");
+               }
 
-       for (mem = grp->gr_mem; *mem; mem++) {
-         struct passwd *pwd = getpwnam (*mem);
+       } /* while (1) */
 
-         if (pwd && (pwd->pw_uid == u))
-               return 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;
        }
-  }
-  return 0;
 }
-
-#endif
+#else
+#define parse_config_file() ((void)0)
+#endif /* FEATURE_SUID_CONFIG */
 
 
-void
-check_suid (struct BB_applet *applet)
+#if ENABLE_FEATURE_SUID
+static void check_suid(const struct bb_applet *applet)
 {
-  uid_t ruid = getuid ();               /* real [ug]id */
-  uid_t rgid = getgid ();
+       uid_t ruid = getuid();               /* real [ug]id */
+       uid_t rgid = getgid();
 
-#ifdef CONFIG_FEATURE_SUID_CONFIG
-  if (config_ok) {
-       struct BB_suid_config *sct;
+#if ENABLE_FEATURE_SUID_CONFIG
+       if (suid_cfg_readable) {
+               struct BB_suid_config *sct;
+               mode_t m;
 
-       for (sct = suid_config; sct; sct = sct->m_next) {
-         if (sct->m_applet == applet)
-               break;
-       }
-       if (sct) {
-         mode_t 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!");
-
-         if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {     /* *both* have to be set for sgid */
-               if (setegid (sct->m_gid))
-                 bb_error_msg_and_die
-                       ("BusyBox binary has insufficient rights to set proper GID for applet!");
-         } else
-               setgid (rgid);                  /* no sgid -> drop */
-
-         if (sct->m_mode & S_ISUID) {
-               if (seteuid (sct->m_uid))
-                 bb_error_msg_and_die
-                       ("BusyBox binary has insufficient rights to set proper UID for applet!");
-         } else
-               setuid (ruid);                  /* no suid -> drop */
-       } else {
-               /* default: drop all priviledges */
-         setgid (rgid);
-         setuid (ruid);
+               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!");
+
+               if (sct->m_gid != 0) {
+                       /* _both_ have to be set for sgid */
+                       if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
+                               xsetgid(sct->m_gid);
+                       } else xsetgid(rgid); /* no sgid -> drop */
+               }
+               if (sct->m_uid != 0) {
+                       if (sct->m_mode & S_ISUID) xsetuid(sct->m_uid);
+                       else xsetuid(ruid); /* no suid -> drop */
+               }
+               return;
        }
-       return;
-  } else {
-#ifndef CONFIG_FEATURE_SUID_CONFIG_QUIET
-       static int onetime = 0;
-
-       if (!onetime) {
-         onetime = 1;
-         fprintf (stderr, "Using fallback suid method\n");
+#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) {
-       if (geteuid () != 0)
-         bb_error_msg_and_die ("This applet requires root priviledges!");
-  } else if (applet->need_suid == _BB_SUID_NEVER) {
-       setgid (rgid);                          /* drop all priviledges */
-       setuid (ruid);
-  }
+       if (applet->need_suid == _BB_SUID_ALWAYS) {
+               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_COMPRESS_USAGE
 
-#ifdef CONFIG_FEATURE_SUID_CONFIG
+#include "usage_compressed.h"
+#include "unarchive.h"
 
+static const char *unpack_usage_messages(void)
+{
+       char *outbuf = NULL;
+       bunzip_data *bd;
+       int i;
+
+       i = start_bunzip(&bd,
+                       /* src_fd: */ -1,
+                       /* inbuf:  */ packed_usage,
+                       /* len:    */ sizeof(packed_usage));
+       /* read_bunzip can longjmp to start_bunzip, and ultimately
+        * end up here with i != 0 on read data errors! Not trivial */
+       if (!i) {
+               /* Cannot use xmalloc: will leak bd in NOFORK case! */
+               outbuf = malloc_or_warn(SIZEOF_usage_messages);
+               if (outbuf)
+                       read_bunzip(bd, outbuf, SIZEOF_usage_messages);
+       }
+       dealloc_bunzip(bd);
+       return outbuf;
+}
+#define dealloc_usage_messages(s) free(s)
 
-#define parse_error(x)  { err=x; goto pe_label; }
+#else
 
+#define unpack_usage_messages() usage_messages
+#define dealloc_usage_messages(s) ((void)(s))
 
-int
-parse_config_file (void)
+#endif /* FEATURE_COMPRESS_USAGE */
+
+
+void bb_show_usage(void)
 {
-  struct stat st;
-  char *err = 0;
-  FILE *f = 0;
-  int lc = 0;
-
-  suid_config = 0;
-
-  /* is there a config file ? */
-  if (stat (CONFIG_FILE, &st) == 0) {
-       /* is it owned by root with no write perm. for group and others ? */
-       if (S_ISREG (st.st_mode) && (st.st_uid == 0)
-               && (!(st.st_mode & (S_IWGRP | S_IWOTH)))) {
-         /* that's ok .. then try to open it */
-         f = fopen (CONFIG_FILE, "r");
-
-         if (f) {
-               char buffer[256];
-               int section = 0;
-
-               while (fgets (buffer, sizeof (buffer) - 1, f)) {
-                 char c = buffer[0];
-                 char *p;
-
-                 lc++;
-
-                 p = strchr (buffer, '#');
-                 if (p)
-                       *p = 0;
-                 p = buffer + bb_strlen (buffer);
-                 while ((p > buffer) && isspace (*--p))
-                       *p = 0;
-
-                 if (p == buffer)
-                       continue;
+       if (ENABLE_SHOW_USAGE) {
+               const char *format_string;
+               const char *p;
+               const char *usage_string = p = unpack_usage_messages();
+               int i;
+
+               i = current_applet - applets;
+               while (i) {
+                       while (*p++) continue;
+                       i--;
+               }
 
-                 if (c == '[') {
-                       p = strchr (buffer, ']');
+               format_string = "%s\n\nUsage: %s %s\n\n";
+               if (*p == '\b')
+                       format_string = "%s\n\nNo help available.\n\n";
+               fprintf(stderr, format_string, bb_msg_full_version,
+                                       applet_name, p);
+               dealloc_usage_messages((char*)usage_string);
+       }
+       xfunc_die();
+}
 
-                       if (!p || (p == (buffer + 1)))  /* no matching ] or empty [] */
-                         parse_error ("malformed section header");
 
-                       *p = 0;
+static int applet_name_compare(const void *name, const void *vapplet)
+{
+       const struct bb_applet *applet = vapplet;
 
-                       if (strcasecmp (buffer + 1, "SUID") == 0)
-                         section = 1;
-                       else
-                         section = -1;         /* unknown section - just skip */
-                 } else if (section) {
-                       switch (section) {
-                       case 1:{                        /* SUID */
-                               int l;
-                               struct BB_applet *applet;
+       return strcmp(name, applet->name);
+}
 
-                               p = strchr (buffer, '=');       /* <key>[::space::]*=[::space::]*<value> */
+const struct bb_applet *find_applet_by_name(const char *name)
+{
+       /* Do a binary search to find the applet entry given the name. */
+       return bsearch(name, applets, NUM_APPLETS, sizeof(applets[0]),
+                               applet_name_compare);
+}
 
-                               if (!p || (p == (buffer + 1)))  /* no = or key is empty */
-                                 parse_error ("malformed keyword");
 
-                               l = p - buffer;
-                               while (isspace (buffer[--l])) {
-                                       /* skip whitespace */
-                               }
+#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 [] = "/usr/bin";
+       static const char usr_sbin[] = "/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_perror_msg("%s", fpc);
+               }
+               free(fpc);
+       }
+}
+#else
+#define install_links(x,y) ((void)0)
+#endif /* FEATURE_INSTALLER */
 
-                               buffer[l + 1] = 0;
-
-                               if ((applet = find_applet_by_name (buffer))) {
-                                 struct BB_suid_config *sct =
-                                       xmalloc (sizeof (struct BB_suid_config));
-
-                                 sct->m_applet = applet;
-                                 sct->m_next = suid_config;
-                                 suid_config = sct;
-
-                                 while (isspace (*++p)) {
-                                       /* skip whitespace */
-                                 }
-
-                                 sct->m_mode = 0;
-
-                                 switch (*p++) {
-                                 case 'S':
-                                       sct->m_mode |= S_ISUID;
-                                       break;
-                                 case 's':
-                                       sct->m_mode |= S_ISUID;
-                                       /* no break */
-                                 case 'x':
-                                       sct->m_mode |= S_IXUSR;
-                                       break;
-                                 case '-':
-                                       break;
-                                 default:
-                                       parse_error ("invalid user mode");
-                                 }
-
-                                 switch (*p++) {
-                                 case 's':
-                                       sct->m_mode |= S_ISGID;
-                                       /* no break */
-                                 case 'x':
-                                       sct->m_mode |= S_IXGRP;
-                                       break;
-                                 case 'S':
-                                       break;
-                                 case '-':
-                                       break;
-                                 default:
-                                       parse_error ("invalid group mode");
-                                 }
-
-                                 switch (*p) {
-                                 case 't':
-                                 case 'x':
-                                       sct->m_mode |= S_IXOTH;
-                                       break;
-                                 case 'T':
-                                 case '-':
-                                       break;
-                                 default:
-                                       parse_error ("invalid other mode");
-                                 }
-
-                                 while (isspace (*++p)) {
-                                       /* skip whitespace */
-                                 }
-
-                                 if (isdigit (*p)) {
-                                       sct->m_uid = strtol (p, &p, 10);
-                                       if (*p++ != '.')
-                                         parse_error ("parsing <uid>.<gid>");
-                                 } else {
-                                       struct passwd *pwd;
-                                       char *p2 = strchr (p, '.');
-
-                                       if (!p2)
-                                         parse_error ("parsing <uid>.<gid>");
-
-                                       *p2 = 0;
-                                       pwd = getpwnam (p);
-
-                                       if (!pwd)
-                                         parse_error ("invalid user name");
 
-                                       sct->m_uid = pwd->pw_uid;
-                                       p = p2 + 1;
-                                 }
-                                 if (isdigit (*p))
-                                       sct->m_gid = strtol (p, &p, 10);
-                                 else {
-                                       struct group *grp = getgrnam (p);
+/* If we were called as "busybox..." */
+static int busybox_main(int argc, char **argv)
+{
+       if (ENABLE_FEATURE_INSTALLER && argc > 1 && !strcmp(argv[1], "--install")) {
+               int use_symbolic_links = 0;
+               char *busybox;
+
+               /* to use symlinks, or not to use symlinks... */
+               if (argc > 2)
+                       if (strcmp(argv[2], "-s") == 0)
+                               use_symbolic_links = 1;
+
+               /* link */
+               busybox = xmalloc_readlink_or_warn("/proc/self/exe");
+               if (!busybox)
+                       return 1;
+               install_links(busybox, use_symbolic_links);
+               if (ENABLE_FEATURE_CLEAN_UP)
+                       free(busybox);
+               return 0;
+       }
 
-                                       if (!grp)
-                                         parse_error ("invalid group name");
+       /* Deal with --help. Also print help when called with no arguments */
+
+       if (argc == 1 || !strcmp(argv[1], "--help") ) {
+               if (argc > 2) {
+                       /* set name for proper "<name>: applet not found" */
+                       applet_name = argv[2];
+                       run_applet_and_exit(applet_name, 2, argv);
+               } else {
+                       const struct bb_applet *a;
+                       int col, output_width;
+
+                       output_width = 80 - sizeof("start-stop-daemon, ") - 8;
+                       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;
+                       }
 
-                                       sct->m_gid = grp->gr_gid;
-                                 }
+                       printf("%s\n"
+                              "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", bb_msg_full_version);
+                       col = 0;
+                       a = applets;
+                       while (a->name) {
+                               col += printf("%s%s", (col ? ", " : "\t"), a->name);
+                               a++;
+                               if (col > output_width && a->name) {
+                                       puts(",");
+                                       col = 0;
                                }
-                               break;
-                         }
-                       default:                        /* unknown - skip */
-                         break;
                        }
-                 } else
-                       parse_error ("keyword not within section");
+                       puts("\n");
+                       return 0;
                }
-               fclose (f);
-               return 1;
-         }
+       } else {
+               /* we want "<argv[1]>: applet not found", not "busybox: ..." */
+               applet_name = argv[1];
+               run_applet_and_exit(argv[1], argc - 1, argv + 1);
        }
-  }
-  return 0;     /* no config file or not readable (not an error) */
 
-pe_label:
-  fprintf (stderr, "Parse error in %s, line %d: %s\n", CONFIG_FILE, lc, err);
+       bb_error_msg_and_die("applet not found");
+}
 
-  if (f)
-       fclose (f);
-  return 0;
+void run_current_applet_and_exit(int argc, char **argv)
+{
+       /* Reinit some shared global data */
+       optind = 1;
+       xfunc_error_retval = EXIT_FAILURE;
+
+       applet_name = current_applet->name;
+       if (argc == 2 && !strcmp(argv[1], "--help"))
+               bb_show_usage();
+       if (ENABLE_FEATURE_SUID)
+               check_suid(current_applet);
+       exit(current_applet->main(argc, argv));
 }
 
-#endif
+void run_applet_and_exit(const char *name, int argc, char **argv)
+{
+       current_applet = find_applet_by_name(name);
+       if (current_applet)
+               run_current_applet_and_exit(argc, argv);
+       if (!strncmp(name, "busybox", 7))
+               exit(busybox_main(argc, argv));
+}
 
-#endif
 
-/* END CODE */
-/*
-Local Variables:
-c-file-style: "linux"
-c-basic-offset: 4
-tab-width: 4
-End:
-*/
+int main(int argc, char **argv)
+{
+       const char *s;
+
+#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++;
+       s = strrchr(applet_name, '/');
+       if (s)
+               applet_name = s + 1;
+
+       if (ENABLE_FEATURE_SUID_CONFIG)
+               parse_config_file();
+
+       /* Set locale for everybody except 'init' */
+       if (ENABLE_LOCALE_SUPPORT && getpid() != 1)
+               setlocale(LC_ALL, "");
+
+       run_applet_and_exit(applet_name, argc, argv);
+       bb_error_msg_and_die("applet not found");
+}