lpr: add more accurate comments
[oweals/busybox.git] / networking / ifupdown.c
index 4ec3d37a88266c7e359110fb148455c9d0106f96..29738c6d0bc20514284ab31bf9407c29fcee5775 100644 (file)
@@ -1,7 +1,7 @@
 /* vi: set sw=4 ts=4: */
 /*
  *  ifupdown for busybox
- *  Copyright (c) 2002 Glenn McGrath <bug1@iinet.net.au>
+ *  Copyright (c) 2002 Glenn McGrath
  *  Copyright (c) 2003-2004 Erik Andersen <andersen@codepoet.org>
  *
  *  Based on ifupdown v 0.6.4 by Anthony Towns
  *  Changes to upstream version
  *  Remove checks for kernel version, assume kernel version 2.2.0 or better.
  *  Lines in the interfaces file cannot wrap.
- *  To adhere to the FHS, the default state file is /var/run/ifstate.
+ *  To adhere to the FHS, the default state file is /var/run/ifstate
+ *  (defined via CONFIG_IFUPDOWN_IFSTATE_PATH) and can be overridden by build
+ *  configuration.
  *
  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  */
 
-#include "busybox.h"
 #include <sys/utsname.h>
 #include <fnmatch.h>
-#include <getopt.h>
+
+#include "libbb.h"
 
 #define MAX_OPT_DEPTH 10
 #define EUNBALBRACK 10001
@@ -36,22 +38,19 @@ struct interface_defn_t;
 
 typedef int execfn(char *command);
 
-struct method_t
-{
-       char *name;
+struct method_t {
+       const char *name;
        int (*up)(struct interface_defn_t *ifd, execfn *e);
        int (*down)(struct interface_defn_t *ifd, execfn *e);
 };
 
-struct address_family_t
-{
-       char *name;
+struct address_family_t {
+       const char *name;
        int n_methods;
        const struct method_t *method;
 };
 
-struct mapping_defn_t
-{
+struct mapping_defn_t {
        struct mapping_defn_t *next;
 
        int max_matches;
@@ -65,14 +64,12 @@ struct mapping_defn_t
        char **mapping;
 };
 
-struct variable_t
-{
+struct variable_t {
        char *name;
        char *value;
 };
 
-struct interface_defn_t
-{
+struct interface_defn_t {
        const struct address_family_t *address_family;
        const struct method_t *method;
 
@@ -82,8 +79,7 @@ struct interface_defn_t
        struct variable_t *option;
 };
 
-struct interfaces_file_t
-{
+struct interfaces_file_t {
        llist_t *autointerfaces;
        llist_t *ifaces;
        struct mapping_defn_t *mappings;
@@ -105,35 +101,10 @@ enum {
 
 static char **my_environ;
 
-static char *startup_PATH;
+static const char *startup_PATH;
 
 #if ENABLE_FEATURE_IFUPDOWN_IPV4 || ENABLE_FEATURE_IFUPDOWN_IPV6
 
-#if ENABLE_FEATURE_IFUPDOWN_IP
-
-static unsigned count_bits(unsigned a)
-{
-       unsigned result;
-       result = (a & 0x55) + ((a >> 1) & 0x55);
-       result = (result & 0x33) + ((result >> 2) & 0x33);
-       return (result & 0x0F) + ((result >> 4) & 0x0F);
-}
-
-static int count_netmask_bits(char *dotted_quad)
-{
-       unsigned result, a, b, c, d;
-       /* Found a netmask...  Check if it is dotted quad */
-       if (sscanf(dotted_quad, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
-               return -1;
-       // FIXME: will be confused by e.g. 255.0.255.0
-       result = count_bits(a);
-       result += count_bits(b);
-       result += count_bits(c);
-       result += count_bits(d);
-       return (int)result;
-}
-#endif
-
 static void addstr(char **bufp, const char *str, size_t str_length)
 {
        /* xasprintf trick will be smaller, but we are often
@@ -162,13 +133,15 @@ static char *get_var(const char *id, size_t idlen, struct interface_defn_t *ifd)
        int i;
 
        if (strncmpz(id, "iface", idlen) == 0) {
-               char *result;
-               static char label_buf[20];
-               safe_strncpy(label_buf, ifd->iface, sizeof(label_buf));
-               result = strchr(label_buf, ':');
-               if (result) {
-                       *result = '\0';
-               }
+               static char *label_buf;
+               //char *result;
+
+               free(label_buf);
+               label_buf = xstrdup(ifd->iface);
+               // Remove virtual iface suffix - why?
+               // ubuntu's ifup doesn't do this
+               //result = strchrnul(label_buf, ':');
+               //*result = '\0';
                return label_buf;
        }
        if (strncmpz(id, "label", idlen) == 0) {
@@ -182,6 +155,39 @@ static char *get_var(const char *id, size_t idlen, struct interface_defn_t *ifd)
        return NULL;
 }
 
+#if ENABLE_FEATURE_IFUPDOWN_IP
+static int count_netmask_bits(const char *dotted_quad)
+{
+//     int result;
+//     unsigned a, b, c, d;
+//     /* Found a netmask...  Check if it is dotted quad */
+//     if (sscanf(dotted_quad, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
+//             return -1;
+//     if ((a|b|c|d) >> 8)
+//             return -1; /* one of numbers is >= 256 */
+//     d |= (a << 24) | (b << 16) | (c << 8); /* IP */
+//     d = ~d; /* 11110000 -> 00001111 */
+
+       /* Shorter version */
+       int result;
+       struct in_addr ip;
+       unsigned d;
+
+       if (inet_aton(dotted_quad, &ip) == 0)
+               return -1; /* malformed dotted IP */
+       d = ntohl(ip.s_addr); /* IP in host order */
+       d = ~d; /* 11110000 -> 00001111 */
+       if (d & (d+1)) /* check that it is in 00001111 form */
+               return -1; /* no it is not */
+       result = 32;
+       while (d) {
+               d >>= 1;
+               result--;
+       }
+       return result;
+}
+#endif
+
 static char *parse(const char *command, struct interface_defn_t *ifd)
 {
        size_t old_pos[MAX_OPT_DEPTH] = { 0 };
@@ -251,11 +257,14 @@ static char *parse(const char *command, struct interface_defn_t *ifd)
                                        if (strncmp(command, "bnmask", 6) == 0) {
                                                unsigned res;
                                                varvalue = get_var("netmask", 7, ifd);
-                                               if (varvalue && (res = count_netmask_bits(varvalue)) > 0) {
-                                                       const char *argument = utoa(res);
-                                                       addstr(&result, argument, strlen(argument));
-                                                       command = nextpercent + 1;
-                                                       break;
+                                               if (varvalue) {
+                                                       res = count_netmask_bits(varvalue);
+                                                       if (res > 0) {
+                                                               const char *argument = utoa(res);
+                                                               addstr(&result, argument, strlen(argument));
+                                                               command = nextpercent + 1;
+                                                               break;
+                                                       }
                                                }
                                        }
 #endif
@@ -380,7 +389,7 @@ static const struct method_t methods6[] = {
 
 static const struct address_family_t addr_inet6 = {
        "inet6",
-       sizeof(methods6) / sizeof(struct method_t),
+       ARRAY_SIZE(methods6),
        methods6
 };
 #endif /* FEATURE_IFUPDOWN_IPV6 */
@@ -427,7 +436,7 @@ static int static_up(struct interface_defn_t *ifd, execfn *exec)
        result += execute("ifconfig %iface% %address% netmask %netmask%"
                                "[[ broadcast %broadcast%]][[ pointopoint %pointopoint%]] ",
                                ifd, exec);
-       result += execute("[[route add default gw %gateway% %iface%]]", ifd, exec);
+       result += execute("[[route add default gw %gateway% %iface%]]", ifd, exec);
        return ((result == 3) ? 3 : 0);
 #endif
 }
@@ -445,7 +454,7 @@ static int static_down(struct interface_defn_t *ifd, execfn *exec)
        return ((result == 2) ? 2 : 0);
 }
 
-#if !ENABLE_APP_UDHCPC
+#if ENABLE_FEATURE_IFUPDOWN_EXTERNAL_DHCP
 struct dhcp_client_t
 {
        const char *name;
@@ -454,59 +463,87 @@ struct dhcp_client_t
 };
 
 static const struct dhcp_client_t ext_dhcp_clients[] = {
-       { "udhcpc",
-               "udhcpc -R -n -p /var/run/udhcpc.%iface%.pid -i %iface%[[ -H %hostname%]][[ -c %clientid%]][[ -s %script%]]",
-               "kill -TERM `cat /var/run/udhcpc.%iface%.pid` 2>/dev/null",
-       },
-       { "pump",
-               "pump -i %iface%[[ -h %hostname%]][[ -l %leasehours%]]",
-               "pump -i %iface% -k",
+       { "dhcpcd",
+               "dhcpcd[[ -h %hostname%]][[ -i %vendor%]][[ -I %clientid%]][[ -l %leasetime%]] %iface%",
+               "dhcpcd -k %iface%",
        },
        { "dhclient",
                "dhclient -pf /var/run/dhclient.%iface%.pid %iface%",
                "kill -9 `cat /var/run/dhclient.%iface%.pid` 2>/dev/null",
        },
-       { "dhcpcd",
-               "dhcpcd[[ -h %hostname%]][[ -i %vendor%]][[ -I %clientid%]][[ -l %leasetime%]] %iface%",
-               "dhcpcd -k %iface%",
+       { "pump",
+               "pump -i %iface%[[ -h %hostname%]][[ -l %leasehours%]]",
+               "pump -i %iface% -k",
+       },
+       { "udhcpc",
+               "udhcpc -R -n -p /var/run/udhcpc.%iface%.pid -i %iface%[[ -H %hostname%]][[ -c %clientid%]][[ -s %script%]]",
+               "kill `cat /var/run/udhcpc.%iface%.pid` 2>/dev/null",
        },
 };
-#endif
+#endif /* ENABLE_FEATURE_IFUPDOWN_EXTERNAL_DHCPC */
 
+#if ENABLE_FEATURE_IFUPDOWN_EXTERNAL_DHCP
 static int dhcp_up(struct interface_defn_t *ifd, execfn *exec)
 {
-#if ENABLE_APP_UDHCPC
-       return execute("udhcpc -R -n -p /var/run/udhcpc.%iface%.pid "
-                       "-i %iface%[[ -H %hostname%]][[ -c %clientid%]][[ -s %script%]]",
-                       ifd, exec);
-#else
-       int i, nclients = sizeof(ext_dhcp_clients) / sizeof(ext_dhcp_clients[0]);
-       for (i = 0; i < nclients; i++) {
+       int i;
+#if ENABLE_FEATURE_IFUPDOWN_IP
+       /* ip doesn't up iface when it configures it (unlike ifconfig) */
+       if (!execute("ip link set %iface% up", ifd, exec))
+               return 0;
+#endif
+       for (i = 0; i < ARRAY_SIZE(ext_dhcp_clients); i++) {
                if (exists_execable(ext_dhcp_clients[i].name))
                        return execute(ext_dhcp_clients[i].startcmd, ifd, exec);
        }
        bb_error_msg("no dhcp clients found");
        return 0;
+}
+#elif ENABLE_APP_UDHCPC
+static int dhcp_up(struct interface_defn_t *ifd, execfn *exec)
+{
+#if ENABLE_FEATURE_IFUPDOWN_IP
+       /* ip doesn't up iface when it configures it (unlike ifconfig) */
+       if (!execute("ip link set %iface% up", ifd, exec))
+               return 0;
 #endif
+       return execute("udhcpc -R -n -p /var/run/udhcpc.%iface%.pid "
+                       "-i %iface%[[ -H %hostname%]][[ -c %clientid%]][[ -s %script%]]",
+                       ifd, exec);
+}
+#else
+static int dhcp_up(struct interface_defn_t *ifd ATTRIBUTE_UNUSED,
+               execfn *exec ATTRIBUTE_UNUSED)
+{
+       return 0; /* no dhcp support */
 }
+#endif
 
+#if ENABLE_FEATURE_IFUPDOWN_EXTERNAL_DHCP
 static int dhcp_down(struct interface_defn_t *ifd, execfn *exec)
 {
-#if ENABLE_APP_UDHCPC
-       return execute("kill -TERM "
-                      "`cat /var/run/udhcpc.%iface%.pid` 2>/dev/null", ifd, exec);
-#else
-       int i, nclients = sizeof(ext_dhcp_clients) / sizeof(ext_dhcp_clients[0]);
-       for (i = 0; i < nclients; i++) {
+       int i;
+       for (i = 0; i < ARRAY_SIZE(ext_dhcp_clients); i++) {
                if (exists_execable(ext_dhcp_clients[i].name))
                        return execute(ext_dhcp_clients[i].stopcmd, ifd, exec);
        }
        bb_error_msg("no dhcp clients found, using static interface shutdown");
        return static_down(ifd, exec);
-#endif
 }
+#elif ENABLE_APP_UDHCPC
+static int dhcp_down(struct interface_defn_t *ifd, execfn *exec)
+{
+       return execute("kill "
+                      "`cat /var/run/udhcpc.%iface%.pid` 2>/dev/null", ifd, exec);
+}
+#else
+static int dhcp_down(struct interface_defn_t *ifd ATTRIBUTE_UNUSED,
+               execfn *exec ATTRIBUTE_UNUSED)
+{
+       return 0; /* no dhcp support */
+}
+#endif
 
-static int manual_up_down(struct interface_defn_t *ifd, execfn *exec)
+static int manual_up_down(struct interface_defn_t *ifd ATTRIBUTE_UNUSED, execfn *exec ATTRIBUTE_UNUSED)
 {
        return 1;
 }
@@ -514,8 +551,8 @@ static int manual_up_down(struct interface_defn_t *ifd, execfn *exec)
 static int bootp_up(struct interface_defn_t *ifd, execfn *exec)
 {
        return execute("bootpc[[ --bootfile %bootfile%]] --dev %iface%"
-                       "[[ --server %server%]][[ --hwaddr %hwaddr%]] "
-                       "--returniffail --serverbcast", ifd, exec);
+                       "[[ --server %server%]][[ --hwaddr %hwaddr%]]"
+                       " --returniffail --serverbcast", ifd, exec);
 }
 
 static int ppp_up(struct interface_defn_t *ifd, execfn *exec)
@@ -552,7 +589,7 @@ static const struct method_t methods[] = {
 
 static const struct address_family_t addr_inet = {
        "inet",
-       sizeof(methods) / sizeof(struct method_t),
+       ARRAY_SIZE(methods),
        methods
 };
 
@@ -560,32 +597,24 @@ static const struct address_family_t addr_inet = {
 
 static char *next_word(char **buf)
 {
-       unsigned short length;
+       unsigned length;
        char *word;
 
-       if (!buf || !*buf || !**buf) {
-               return NULL;
-       }
-
        /* Skip over leading whitespace */
        word = skip_whitespace(*buf);
 
-       /* Skip over comments */
-       if (*word == '#') {
+       /* Stop on EOL */
+       if (*word == '\0')
                return NULL;
-       }
 
-       /* Find the length of this word */
+       /* Find the length of this word (can't be 0) */
        length = strcspn(word, " \t\n");
-       if (length == 0) {
-               return NULL;
-       }
+
+       /* Unless we are already at NUL, store NUL and advance */
+       if (word[length] != '\0')
+               word[length++] = '\0';
+
        *buf = word + length;
-       /*DBU:[dave@cray.com] if we are already at EOL dont't increment beyond it */
-       if (**buf) {
-               **buf = '\0';
-               (*buf)++;
-       }
 
        return word;
 }
@@ -611,7 +640,7 @@ static const struct method_t *get_method(const struct address_family_t *af, char
 
        if (!name)
                return NULL;
-
+       /* TODO: use index_in_str_array() */
        for (i = 0; i < af->n_methods; i++) {
                if (strcmp(af->method[i].name, name) == 0) {
                        return &af->method[i];
@@ -636,58 +665,84 @@ static const llist_t *find_list_string(const llist_t *list, const char *string)
 
 static struct interfaces_file_t *read_interfaces(const char *filename)
 {
+       /* Let's try to be compatible.
+        *
+        * "man 5 interfaces" says:
+        * Lines starting with "#" are ignored. Note that end-of-line
+        * comments are NOT supported, comments must be on a line of their own.
+        * A line may be extended across multiple lines by making
+        * the last character a backslash.
+        *
+        * Seen elsewhere in example config file:
+        * A "#" character in the very first column makes the rest of the line
+        * be ignored. Blank lines are ignored. Lines may be indented freely.
+        * A "\" character at the very end of the line indicates the next line
+        * should be treated as a continuation of the current one.
+        */
 #if ENABLE_FEATURE_IFUPDOWN_MAPPING
        struct mapping_defn_t *currmap = NULL;
 #endif
        struct interface_defn_t *currif = NULL;
        struct interfaces_file_t *defn;
        FILE *f;
-       char *firstword;
        char *buf;
-
+       char *first_word;
+       char *rest_of_line;
        enum { NONE, IFACE, MAPPING } currently_processing = NONE;
 
-       defn = xzalloc(sizeof(struct interfaces_file_t));
-
+       defn = xzalloc(sizeof(*defn));
        f = xfopen(filename, "r");
 
        while ((buf = xmalloc_getline(f)) != NULL) {
-               char *buf_ptr = buf;
-
-               firstword = next_word(&buf_ptr);
-               if (firstword == NULL) {
+#if ENABLE_DESKTOP
+               /* Trailing "\" concatenates lines */
+               char *p;
+               while ((p = last_char_is(buf, '\\')) != NULL) {
+                       *p = '\0';
+                       rest_of_line = xmalloc_getline(f);
+                       if (!rest_of_line)
+                               break;
+                       p = xasprintf("%s%s", buf, rest_of_line);
                        free(buf);
-                       continue;       /* blank line */
+                       free(rest_of_line);
+                       buf = p;
+               }
+#endif
+               rest_of_line = buf;
+               first_word = next_word(&rest_of_line);
+               if (!first_word || *buf == '#') {
+                       free(buf);
+                       continue; /* blank/comment line */
                }
 
-               if (strcmp(firstword, "mapping") == 0) {
+               if (strcmp(first_word, "mapping") == 0) {
 #if ENABLE_FEATURE_IFUPDOWN_MAPPING
-                       currmap = xzalloc(sizeof(struct mapping_defn_t));
+                       currmap = xzalloc(sizeof(*currmap));
 
-                       while ((firstword = next_word(&buf_ptr)) != NULL) {
-                               if (currmap->max_matches == currmap->n_matches) {
+                       while ((first_word = next_word(&rest_of_line)) != NULL) {
+                               if (currmap->n_matches >= currmap->max_matches) {
                                        currmap->max_matches = currmap->max_matches * 2 + 1;
-                                       currmap->match = xrealloc(currmap->match, sizeof(currmap->match) * currmap->max_matches);
+                                       currmap->match = xrealloc(currmap->match,
+                                               sizeof(*currmap->match) * currmap->max_matches);
                                }
-
-                               currmap->match[currmap->n_matches++] = xstrdup(firstword);
+                               currmap->match[currmap->n_matches++] = xstrdup(first_word);
                        }
-                       currmap->max_mappings = 0;
-                       currmap->n_mappings = 0;
-                       currmap->mapping = NULL;
-                       currmap->script = NULL;
+                       /*currmap->max_mappings = 0; - done by xzalloc */
+                       /*currmap->n_mappings = 0;*/
+                       /*currmap->mapping = NULL;*/
+                       /*currmap->script = NULL;*/
                        {
                                struct mapping_defn_t **where = &defn->mappings;
                                while (*where != NULL) {
                                        where = &(*where)->next;
                                }
                                *where = currmap;
-                               currmap->next = NULL;
+                               /*currmap->next = NULL;*/
                        }
                        debug_noise("Added mapping\n");
 #endif
                        currently_processing = MAPPING;
-               } else if (strcmp(firstword, "iface") == 0) {
+               } else if (strcmp(first_word, "iface") == 0) {
                        static const struct address_family_t *const addr_fams[] = {
 #if ENABLE_FEATURE_IFUPDOWN_IPV4
                                &addr_inet,
@@ -697,145 +752,117 @@ static struct interfaces_file_t *read_interfaces(const char *filename)
 #endif
                                NULL
                        };
-
                        char *iface_name;
                        char *address_family_name;
                        char *method_name;
                        llist_t *iface_list;
 
-                       currif = xzalloc(sizeof(struct interface_defn_t));
-                       iface_name = next_word(&buf_ptr);
-                       address_family_name = next_word(&buf_ptr);
-                       method_name = next_word(&buf_ptr);
+                       currif = xzalloc(sizeof(*currif));
+                       iface_name = next_word(&rest_of_line);
+                       address_family_name = next_word(&rest_of_line);
+                       method_name = next_word(&rest_of_line);
 
-                       if (buf_ptr == NULL) {
-                               bb_error_msg("too few parameters for line \"%s\"", buf);
-                               return NULL;
-                       }
+                       if (method_name == NULL)
+                               bb_error_msg_and_die("too few parameters for line \"%s\"", buf);
 
                        /* ship any trailing whitespace */
-                       buf_ptr = skip_whitespace(buf_ptr);
+                       rest_of_line = skip_whitespace(rest_of_line);
 
-                       if (buf_ptr[0] != '\0') {
-                               bb_error_msg("too many parameters \"%s\"", buf);
-                               return NULL;
-                       }
+                       if (rest_of_line[0] != '\0' /* && rest_of_line[0] != '#' */)
+                               bb_error_msg_and_die("too many parameters \"%s\"", buf);
 
                        currif->iface = xstrdup(iface_name);
 
                        currif->address_family = get_address_family(addr_fams, address_family_name);
-                       if (!currif->address_family) {
-                               bb_error_msg("unknown address type \"%s\"", address_family_name);
-                               return NULL;
-                       }
+                       if (!currif->address_family)
+                               bb_error_msg_and_die("unknown address type \"%s\"", address_family_name);
 
                        currif->method = get_method(currif->address_family, method_name);
-                       if (!currif->method) {
-                               bb_error_msg("unknown method \"%s\"", method_name);
-                               return NULL;
-                       }
+                       if (!currif->method)
+                               bb_error_msg_and_die("unknown method \"%s\"", method_name);
 
                        for (iface_list = defn->ifaces; iface_list; iface_list = iface_list->link) {
                                struct interface_defn_t *tmp = (struct interface_defn_t *) iface_list->data;
-                               if ((strcmp(tmp->iface, currif->iface) == 0) &&
-                                       (tmp->address_family == currif->address_family)) {
-                                       bb_error_msg("duplicate interface \"%s\"", tmp->iface);
-                                       return NULL;
+                               if ((strcmp(tmp->iface, currif->iface) == 0)
+                                && (tmp->address_family == currif->address_family)
+                               ) {
+                                       bb_error_msg_and_die("duplicate interface \"%s\"", tmp->iface);
                                }
                        }
                        llist_add_to_end(&(defn->ifaces), (char*)currif);
 
                        debug_noise("iface %s %s %s\n", currif->iface, address_family_name, method_name);
                        currently_processing = IFACE;
-               } else if (strcmp(firstword, "auto") == 0) {
-                       while ((firstword = next_word(&buf_ptr)) != NULL) {
+               } else if (strcmp(first_word, "auto") == 0) {
+                       while ((first_word = next_word(&rest_of_line)) != NULL) {
 
                                /* Check the interface isnt already listed */
-                               if (find_list_string(defn->autointerfaces, firstword)) {
+                               if (find_list_string(defn->autointerfaces, first_word)) {
                                        bb_perror_msg_and_die("interface declared auto twice \"%s\"", buf);
                                }
 
                                /* Add the interface to the list */
-                               llist_add_to_end(&(defn->autointerfaces), xstrdup(firstword));
-                               debug_noise("\nauto %s\n", firstword);
+                               llist_add_to_end(&(defn->autointerfaces), xstrdup(first_word));
+                               debug_noise("\nauto %s\n", first_word);
                        }
                        currently_processing = NONE;
                } else {
                        switch (currently_processing) {
                        case IFACE:
-                               {
+                               if (rest_of_line[0] == '\0')
+                                       bb_error_msg_and_die("option with empty value \"%s\"", buf);
+
+                               if (strcmp(first_word, "up") != 0
+                                && strcmp(first_word, "down") != 0
+                                && strcmp(first_word, "pre-up") != 0
+                                && strcmp(first_word, "post-down") != 0
+                               ) {
                                        int i;
-
-                                       if (strlen(buf_ptr) == 0) {
-                                               bb_error_msg("option with empty value \"%s\"", buf);
-                                               return NULL;
-                                       }
-
-                                       if (strcmp(firstword, "up") != 0
-                                                       && strcmp(firstword, "down") != 0
-                                                       && strcmp(firstword, "pre-up") != 0
-                                                       && strcmp(firstword, "post-down") != 0) {
-                                               for (i = 0; i < currif->n_options; i++) {
-                                                       if (strcmp(currif->option[i].name, firstword) == 0) {
-                                                               bb_error_msg("duplicate option \"%s\"", buf);
-                                                               return NULL;
-                                                       }
-                                               }
+                                       for (i = 0; i < currif->n_options; i++) {
+                                               if (strcmp(currif->option[i].name, first_word) == 0)
+                                                       bb_error_msg_and_die("duplicate option \"%s\"", buf);
                                        }
                                }
                                if (currif->n_options >= currif->max_options) {
-                                       struct variable_t *opt;
-
-                                       currif->max_options = currif->max_options + 10;
-                                       opt = xrealloc(currif->option, sizeof(*opt) * currif->max_options);
-                                       currif->option = opt;
-                               }
-                               currif->option[currif->n_options].name = xstrdup(firstword);
-                               currif->option[currif->n_options].value = xstrdup(buf_ptr);
-                               if (!currif->option[currif->n_options].name) {
-                                       perror(filename);
-                                       return NULL;
+                                       currif->max_options += 10;
+                                       currif->option = xrealloc(currif->option,
+                                               sizeof(*currif->option) * currif->max_options);
                                }
-                               if (!currif->option[currif->n_options].value) {
-                                       perror(filename);
-                                       return NULL;
-                               }
-                               debug_noise("\t%s=%s\n", currif->option[currif->n_options].name,
-                                               currif->option[currif->n_options].value);
+                               debug_noise("\t%s=%s\n", first_word, rest_of_line);
+                               currif->option[currif->n_options].name = xstrdup(first_word);
+                               currif->option[currif->n_options].value = xstrdup(rest_of_line);
                                currif->n_options++;
                                break;
                        case MAPPING:
 #if ENABLE_FEATURE_IFUPDOWN_MAPPING
-                               if (strcmp(firstword, "script") == 0) {
-                                       if (currmap->script != NULL) {
-                                               bb_error_msg("duplicate script in mapping \"%s\"", buf);
-                                               return NULL;
-                                       } else {
-                                               currmap->script = xstrdup(next_word(&buf_ptr));
-                                       }
-                               } else if (strcmp(firstword, "map") == 0) {
-                                       if (currmap->max_mappings == currmap->n_mappings) {
+                               if (strcmp(first_word, "script") == 0) {
+                                       if (currmap->script != NULL)
+                                               bb_error_msg_and_die("duplicate script in mapping \"%s\"", buf);
+                                       currmap->script = xstrdup(next_word(&rest_of_line));
+                               } else if (strcmp(first_word, "map") == 0) {
+                                       if (currmap->n_mappings >= currmap->max_mappings) {
                                                currmap->max_mappings = currmap->max_mappings * 2 + 1;
-                                               currmap->mapping = xrealloc(currmap->mapping, sizeof(char *) * currmap->max_mappings);
+                                               currmap->mapping = xrealloc(currmap->mapping,
+                                                       sizeof(char *) * currmap->max_mappings);
                                        }
-                                       currmap->mapping[currmap->n_mappings] = xstrdup(next_word(&buf_ptr));
+                                       currmap->mapping[currmap->n_mappings] = xstrdup(next_word(&rest_of_line));
                                        currmap->n_mappings++;
                                } else {
-                                       bb_error_msg("misplaced option \"%s\"", buf);
-                                       return NULL;
+                                       bb_error_msg_and_die("misplaced option \"%s\"", buf);
                                }
 #endif
                                break;
                        case NONE:
                        default:
-                               bb_error_msg("misplaced option \"%s\"", buf);
-                               return NULL;
+                               bb_error_msg_and_die("misplaced option \"%s\"", buf);
                        }
                }
                free(buf);
-       }
+       } /* while (fgets) */
+
        if (ferror(f) != 0) {
-               bb_perror_msg_and_die("%s", filename);
+               /* ferror does NOT set errno! */
+               bb_error_msg_and_die("%s: I/O error", filename);
        }
        fclose(f);
 
@@ -885,9 +912,10 @@ static void set_environ(struct interface_defn_t *iface, const char *mode)
 
        for (i = 0; i < iface->n_options; i++) {
                if (strcmp(iface->option[i].name, "up") == 0
-                               || strcmp(iface->option[i].name, "down") == 0
-                               || strcmp(iface->option[i].name, "pre-up") == 0
-                               || strcmp(iface->option[i].name, "post-down") == 0) {
+                || strcmp(iface->option[i].name, "down") == 0
+                || strcmp(iface->option[i].name, "pre-up") == 0
+                || strcmp(iface->option[i].name, "post-down") == 0
+               ) {
                        continue;
                }
                *(environend++) = setlocalenv("IF_%s=%s", iface->option[i].name, iface->option[i].value);
@@ -910,15 +938,15 @@ static int doit(char *str)
                int status;
 
                fflush(NULL);
-               child = fork();
+               child = vfork();
                switch (child) {
                case -1: /* failure */
                        return 0;
                case 0: /* child */
                        execle(DEFAULT_SHELL, DEFAULT_SHELL, "-c", str, NULL, my_environ);
-                       exit(127);
+                       _exit(127);
                }
-               waitpid(child, &status, 0);
+               safe_waitpid(child, &status, 0);
                if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
                        return 0;
                }
@@ -969,60 +997,39 @@ static int iface_down(struct interface_defn_t *iface)
 }
 
 #if ENABLE_FEATURE_IFUPDOWN_MAPPING
-static int popen2(FILE **in, FILE **out, char *command, ...)
+static int popen2(FILE **in, FILE **out, char *command, char *param)
 {
-       va_list ap;
-       char *argv[11] = { command };
-       int argc;
-       int infd[2], outfd[2];
+       char *argv[3] = { command, param, NULL };
+       struct fd_pair infd, outfd;
        pid_t pid;
 
-       argc = 1;
-       va_start(ap, command);
-       while ((argc < 10) && (argv[argc] = va_arg(ap, char *))) {
-               argc++;
-       }
-       argv[argc] = NULL;      /* make sure */
-       va_end(ap);
-
-       if (pipe(infd) != 0) {
-               return 0;
-       }
-
-       if (pipe(outfd) != 0) {
-               close(infd[0]);
-               close(infd[1]);
-               return 0;
-       }
+       xpiped_pair(infd);
+       xpiped_pair(outfd);
 
        fflush(NULL);
-       switch (pid = fork()) {
-       case -1:                        /* failure */
-               close(infd[0]);
-               close(infd[1]);
-               close(outfd[0]);
-               close(outfd[1]);
-               return 0;
-       case 0:                 /* child */
-               dup2(infd[0], 0);
-               dup2(outfd[1], 1);
-               close(infd[0]);
-               close(infd[1]);
-               close(outfd[0]);
-               close(outfd[1]);
-               execvp(command, argv);
-               exit(127);
-       default:                        /* parent */
-               *in = fdopen(infd[1], "w");
-               *out = fdopen(outfd[0], "r");
-               close(infd[0]);
-               close(outfd[1]);
-               return pid;
+       pid = vfork();
+
+       switch (pid) {
+       case -1:  /* failure */
+               bb_perror_msg_and_die("vfork");
+       case 0:  /* child */
+               /* NB: close _first_, then move fds! */
+               close(infd.wr);
+               close(outfd.rd);
+               xmove_fd(infd.rd, 0);
+               xmove_fd(outfd.wr, 1);
+               BB_EXECVP(command, argv);
+               _exit(127);
        }
-       /* unreached */
+       /* parent */
+       close(infd.rd);
+       close(outfd.wr);
+       *in = fdopen(infd.wr, "w");
+       *out = fdopen(outfd.rd, "r");
+       return pid;
 }
 
-static char *run_mapping(char *physical, struct mapping_defn_t * map)
+static char *run_mapping(char *physical, struct mapping_defn_t *map)
 {
        FILE *in, *out;
        int i, status;
@@ -1030,27 +1037,23 @@ static char *run_mapping(char *physical, struct mapping_defn_t * map)
 
        char *logical = xstrdup(physical);
 
-       /* Run the mapping script. */
-       pid = popen2(&in, &out, map->script, physical, NULL);
-
-       /* popen2() returns 0 on failure. */
-       if (pid == 0)
-               return logical;
+       /* Run the mapping script. Never fails. */
+       pid = popen2(&in, &out, map->script, physical);
 
        /* Write mappings to stdin of mapping script. */
        for (i = 0; i < map->n_mappings; i++) {
                fprintf(in, "%s\n", map->mapping[i]);
        }
        fclose(in);
-       waitpid(pid, &status, 0);
+       safe_waitpid(pid, &status, 0);
 
        if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
                /* If the mapping script exited successfully, try to
                 * grab a line of output and use that as the name of the
                 * logical interface. */
-               char *new_logical = xmalloc(MAX_INTERFACE_LENGTH);
+               char *new_logical = xmalloc_getline(out);
 
-               if (fgets(new_logical, MAX_INTERFACE_LENGTH, out)) {
+               if (new_logical) {
                        /* If we are able to read a line of output from the script,
                         * remove any trailing whitespace and use this value
                         * as the name of the logical interface. */
@@ -1061,10 +1064,6 @@ static char *run_mapping(char *physical, struct mapping_defn_t * map)
 
                        free(logical);
                        logical = new_logical;
-               } else {
-                       /* If we are UNABLE to read a line of output, discard our
-                        * freshly allocated memory. */
-                       free(new_logical);
                }
        }
 
@@ -1076,12 +1075,13 @@ static char *run_mapping(char *physical, struct mapping_defn_t * map)
 
 static llist_t *find_iface_state(llist_t *state_list, const char *iface)
 {
-       unsigned short iface_len = strlen(iface);
+       unsigned iface_len = strlen(iface);
        llist_t *search = state_list;
 
        while (search) {
-               if ((strncmp(search->data, iface, iface_len) == 0) &&
-                               (search->data[iface_len] == '=')) {
+               if ((strncmp(search->data, iface, iface_len) == 0)
+                && (search->data[iface_len] == '=')
+               ) {
                        return search;
                }
                search = search->link;
@@ -1089,14 +1089,34 @@ static llist_t *find_iface_state(llist_t *state_list, const char *iface)
        return NULL;
 }
 
+/* read the previous state from the state file */
+static llist_t *read_iface_state(void)
+{
+       llist_t *state_list = NULL;
+       FILE *state_fp = fopen(CONFIG_IFUPDOWN_IFSTATE_PATH, "r");
+
+       if (state_fp) {
+               char *start, *end_ptr;
+               while ((start = xmalloc_fgets(state_fp)) != NULL) {
+                       /* We should only need to check for a single character */
+                       end_ptr = start + strcspn(start, " \t\n");
+                       *end_ptr = '\0';
+                       llist_add_to(&state_list, start);
+               }
+               fclose(state_fp);
+       }
+       return state_list;
+}
+
+
+int ifupdown_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int ifupdown_main(int argc, char **argv)
 {
-       int (*cmds)(struct interface_defn_t *) = NULL;
+       int (*cmds)(struct interface_defn_t *);
        struct interfaces_file_t *defn;
-       llist_t *state_list = NULL;
        llist_t *target_list = NULL;
        const char *interfaces = "/etc/network/interfaces";
-       int any_failures = 0;
+       bool any_failures = 0;
 
        cmds = iface_down;
        if (applet_name[2] == 'u') {
@@ -1104,7 +1124,7 @@ int ifupdown_main(int argc, char **argv)
                cmds = iface_up;
        }
 
-       getopt32(argc, argv, OPTION_STR, &interfaces);
+       getopt32(argv, OPTION_STR, &interfaces);
        if (argc - optind > 0) {
                if (DO_ALL) bb_show_usage();
        } else {
@@ -1115,26 +1135,12 @@ int ifupdown_main(int argc, char **argv)
        defn = read_interfaces(interfaces);
        debug_noise("\ndone reading %s\n\n", interfaces);
 
-       if (!defn) {
-               return EXIT_FAILURE;
-       }
-
        startup_PATH = getenv("PATH");
        if (!startup_PATH) startup_PATH = "";
 
        /* Create a list of interfaces to work on */
        if (DO_ALL) {
-               if (cmds == iface_up) {
-                       target_list = defn->autointerfaces;
-               } else {
-                       /* iface_down */
-                       const llist_t *list = state_list;
-                       while (list) {
-                               llist_add_to_end(&target_list, xstrdup(list->data));
-                               list = list->link;
-                       }
-                       target_list = defn->autointerfaces;
-               }
+               target_list = defn->autointerfaces;
        } else {
                llist_add_to_end(&target_list, argv[optind]);
        }
@@ -1146,8 +1152,8 @@ int ifupdown_main(int argc, char **argv)
                char *iface;
                char *liface;
                char *pch;
-               int okay = 0;
-               int cmds_ret;
+               bool okay = 0;
+               unsigned cmds_ret;
 
                iface = xstrdup(target_list->data);
                target_list = target_list->link;
@@ -1161,6 +1167,7 @@ int ifupdown_main(int argc, char **argv)
                }
 
                if (!FORCE) {
+                       llist_t *state_list = read_iface_state();
                        const llist_t *iface_state = find_iface_state(state_list, iface);
 
                        if (cmds == iface_up) {
@@ -1171,11 +1178,12 @@ int ifupdown_main(int argc, char **argv)
                                }
                        } else {
                                /* ifdown */
-                               if (iface_state) {
+                               if (!iface_state) {
                                        bb_error_msg("interface %s not configured", iface);
                                        continue;
                                }
                        }
+                       llist_free(state_list, free);
                }
 
 #if ENABLE_FEATURE_IFUPDOWN_MAPPING
@@ -1223,17 +1231,21 @@ int ifupdown_main(int argc, char **argv)
                        iface_list = iface_list->link;
                }
                if (VERBOSE) {
-                       puts("");
+                       bb_putchar('\n');
                }
 
                if (!okay && !FORCE) {
                        bb_error_msg("ignoring unknown interface %s", liface);
                        any_failures = 1;
-               } else {
+               } else if (!NO_ACT) {
+                       /* update the state file */
+                       FILE *state_fp;
+                       llist_t *state;
+                       llist_t *state_list = read_iface_state();
                        llist_t *iface_state = find_iface_state(state_list, iface);
 
                        if (cmds == iface_up) {
-                               char *newiface = xasprintf("%s=%s", iface, liface);
+                               char * const newiface = xasprintf("%s=%s", iface, liface);
                                if (iface_state == NULL) {
                                        llist_add_to_end(&state_list, newiface);
                                } else {
@@ -1241,24 +1253,23 @@ int ifupdown_main(int argc, char **argv)
                                        iface_state->data = newiface;
                                }
                        } else {
-                               /* Remove an interface from the linked list */
+                               /* Remove an interface from state_list */
+                               llist_unlink(&state_list, iface_state);
                                free(llist_pop(&iface_state));
                        }
-               }
-       }
-
-       /* Actually write the new state */
-       if (!NO_ACT) {
-               FILE *state_fp;
 
-               state_fp = xfopen("/var/run/ifstate", "w");
-               while (state_list) {
-                       if (state_list->data) {
-                               fprintf(state_fp, "%s\n", state_list->data);
+                       /* Actually write the new state */
+                       state_fp = xfopen(CONFIG_IFUPDOWN_IFSTATE_PATH, "w");
+                       state = state_list;
+                       while (state) {
+                               if (state->data) {
+                                       fprintf(state_fp, "%s\n", state->data);
+                               }
+                               state = state->link;
                        }
-                       state_list = state_list->link;
+                       fclose(state_fp);
+                       llist_free(state_list, free);
                }
-               fclose(state_fp);
        }
 
        return any_failures;