mdev: don't reparse rules on -s

function                                             old     new   delta
make_device                                         1648    1843    +195
clean_up_cur_rule                                      -      61     +61
make_default_cur_rule                                  -      41     +41
mdev_main                                            690     712     +22
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 2/0 up/down: 319/0)             Total: 319 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 341 insertions, 217 deletions

diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index c56741b08..0b3e06cf1 100644
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -168,9 +168,29 @@
  * This happens regardless of /sys/class/.../dev existence.
  */
 
+struct rule {
+        bool keep_matching;
+        bool regex_compiled;
+        bool regex_has_slash;
+        mode_t mode;
+        int maj, min0, min1;
+        struct bb_uidgid_t ugid;
+        char *envvar;
+        char *ren_mov;
+        IF_FEATURE_MDEV_EXEC(char *r_cmd;)
+        regex_t match;
+};
+
 struct globals {
         int root_major, root_minor;
         char *subsystem;
+#if ENABLE_FEATURE_MDEV_CONF
+        const char *filename;
+        parser_t *parser;
+        struct rule **rule_vec;
+        unsigned rule_idx;
+#endif
+        struct rule cur_rule;
 } FIX_ALIASING;
 #define G (*(struct globals*)&bb_common_bufsiz1)
 #define INIT_G() do { } while (0)
@@ -182,6 +202,164 @@ struct globals {
 /* We use additional 64+ bytes in make_device() */
 #define SCRATCH_SIZE 80
 
+#if 0
+# define dbg(...) bb_error_msg(__VA_ARGS__)
+#else
+# define dbg(...) ((void)0)
+#endif
+
+
+#if ENABLE_FEATURE_MDEV_CONF
+
+static void make_default_cur_rule(void)
+{
+        memset(&G.cur_rule, 0, sizeof(G.cur_rule));
+        G.cur_rule.maj = -1; /* "not a @major,minor rule" */
+        G.cur_rule.mode = 0660;
+}
+
+static void clean_up_cur_rule(void)
+{
+        free(G.cur_rule.envvar);
+        if (G.cur_rule.regex_compiled)
+                regfree(&G.cur_rule.match);
+        free(G.cur_rule.ren_mov);
+        IF_FEATURE_MDEV_EXEC(free(G.cur_rule.r_cmd);)
+        make_default_cur_rule();
+}
+
+static void parse_next_rule(void)
+{
+        /* Note: on entry, G.cur_rule is set to default */
+        while (1) {
+                char *tokens[4];
+                char *val;
+
+                if (!config_read(G.parser, tokens, 4, 3, "# \t", PARSE_NORMAL))
+                        break;
+
+                /* Fields: [-]regex uid:gid mode [alias] [cmd] */
+                dbg("token1:'%s'", tokens[1]);
+
+                /* 1st field */
+                val = tokens[0];
+                G.cur_rule.keep_matching = ('-' == val[0]);
+                val += G.cur_rule.keep_matching; /* swallow leading dash */
+                if (val[0] == '@') {
+                        /* @major,minor[-minor2] */
+                        /* (useful when name is ambiguous:
+                         * "/sys/class/usb/lp0" and
+                         * "/sys/class/printer/lp0")
+                         */
+                        int sc = sscanf(val, "@%u,%u-%u", &G.cur_rule.maj, &G.cur_rule.min0, &G.cur_rule.min1);
+                        if (sc < 2 || G.cur_rule.maj < 0) {
+                                bb_error_msg("bad @maj,min on line %d", G.parser->lineno);
+                                goto next_rule;
+                        }
+                        if (sc == 2)
+                                G.cur_rule.min1 = G.cur_rule.min0;
+                } else {
+                        if (val[0] == '$') {
+                                char *eq = strchr(++val, '=');
+                                if (!eq) {
+                                        bb_error_msg("bad $envvar=regex on line %d", G.parser->lineno);
+                                        goto next_rule;
+                                }
+                                G.cur_rule.envvar = xstrndup(val, eq - val);
+                                val = eq + 1;
+                        }
+                        xregcomp(&G.cur_rule.match, val, REG_EXTENDED);
+                        G.cur_rule.regex_compiled = 1;
+                        G.cur_rule.regex_has_slash = (strchr(val, '/') != NULL);
+                }
+
+                /* 2nd field: uid:gid - device ownership */
+                if (get_uidgid(&G.cur_rule.ugid, tokens[1], /*allow_numeric:*/ 1) == 0) {
+                        bb_error_msg("unknown user/group '%s' on line %d", tokens[1], G.parser->lineno);
+                        goto next_rule;
+                }
+
+                /* 3rd field: mode - device permissions */
+                bb_parse_mode(tokens[2], &G.cur_rule.mode);
+
+                /* 4th field (opt): ">|=alias" or "!" to not create the node */
+                val = tokens[3];
+                if (ENABLE_FEATURE_MDEV_RENAME && val && strchr(">=!", val[0])) {
+                        char *s = skip_non_whitespace(val);
+                        G.cur_rule.ren_mov = xstrndup(val, s - val);
+                        val = skip_whitespace(s);
+                }
+
+                if (ENABLE_FEATURE_MDEV_EXEC && val && val[0]) {
+                        const char *s = "$@*";
+                        const char *s2 = strchr(s, val[0]);
+                        if (!s2) {
+                                bb_error_msg("bad line %u", G.parser->lineno);
+                                goto next_rule;
+                        }
+                        IF_FEATURE_MDEV_EXEC(G.cur_rule.r_cmd = xstrdup(val);)
+                }
+
+                return;
+ next_rule:
+                clean_up_cur_rule();
+        } /* while (config_read) */
+
+        dbg("config_close(G.parser)");
+        config_close(G.parser);
+        G.parser = NULL;
+
+        return;
+}
+
+/* If mdev -s, we remember rules in G.rule_vec[].
+ * Otherwise, there is no point in doing it, and we just
+ * save only one parsed rule in G.cur_rule.
+ */
+static const struct rule *next_rule(void)
+{
+        struct rule *rule;
+
+        /* Open conf file if we didn't do it yet */
+        if (!G.parser && G.filename) {
+                dbg("config_open('%s')", G.filename);
+                G.parser = config_open2(G.filename, fopen_for_read);
+                G.filename = NULL;
+        }
+
+        if (G.rule_vec) {
+                /* mdev -s */
+                /* Do we have rule parsed already? */
+                if (G.rule_vec[G.rule_idx]) {
+                        dbg("< G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
+                        return G.rule_vec[G.rule_idx++];
+                }
+                make_default_cur_rule();
+        } else {
+                /* not mdev -s */
+                clean_up_cur_rule();
+        }
+
+        /* Parse one more rule if file isn't fully read */
+        rule = &G.cur_rule;
+        if (G.parser) {
+                parse_next_rule();
+                if (G.rule_vec) { /* mdev -s */
+                        rule = memcpy(xmalloc(sizeof(G.cur_rule)), &G.cur_rule, sizeof(G.cur_rule));
+                        G.rule_vec = xrealloc_vector(G.rule_vec, 4, G.rule_idx);
+                        G.rule_vec[G.rule_idx++] = rule;
+                        dbg("> G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
+                }
+        }
+
+        return rule;
+}
+
+#else
+
+# define next_rule() (&G.cur_rule)
+
+#endif
 
 /* Builds an alias path.
  * This function potentionally reallocates the alias parameter.
@@ -218,8 +396,8 @@ static void make_device(char *path, int delete)
 {
         char *device_name, *subsystem_slash_devname;
         int major, minor, type, len;
-        mode_t mode;
-        parser_t *parser;
+
+        dbg("%s('%s', delete:%d)", __func__, path, delete);
 
         /* Try to read major/minor string.  Note that the kernel puts \n after
          * the data, so we don't need to worry about null terminating the string
@@ -272,246 +450,184 @@ static void make_device(char *path, int delete)
                 path = subsystem_slash_devname;
         }
 
-        /* If we have config file, look up user settings */
-        if (ENABLE_FEATURE_MDEV_CONF)
-                parser = config_open2("/etc/mdev.conf", fopen_for_read);
-
-        do {
-                int keep_matching;
-                struct bb_uidgid_t ugid;
-                char *tokens[4];
-                char *command = NULL;
-                char *alias = NULL;
+#if ENABLE_FEATURE_MDEV_CONF
+        G.rule_idx = 0; /* restart from the beginning (think mdev -s) */
+#endif
+        for (;;) {
+                const char *str_to_match;
+                regmatch_t off[1 + 9 * ENABLE_FEATURE_MDEV_RENAME_REGEXP];
+                char *command;
+                char *alias;
                 char aliaslink = aliaslink; /* for compiler */
+                const char *node_name;
+                const struct rule *rule;
 
-                /* Defaults in case we won't match any line */
-                ugid.uid = ugid.gid = 0;
-                keep_matching = 0;
-                mode = 0660;
-
-                if (ENABLE_FEATURE_MDEV_CONF
-                 && config_read(parser, tokens, 4, 3, "# \t", PARSE_NORMAL)
-                ) {
-                        char *val;
-                        char *str_to_match;
-                        regmatch_t off[1 + 9 * ENABLE_FEATURE_MDEV_RENAME_REGEXP];
-
-                        val = tokens[0];
-                        keep_matching = ('-' == val[0]);
-                        val += keep_matching; /* swallow leading dash */
-
-                        /* Match against either "subsystem/device_name"
-                         * or "device_name" alone */
-                        str_to_match = strchr(val, '/') ? path : device_name;
-
-                        /* Fields: regex uid:gid mode [alias] [cmd] */
-
-                        if (val[0] == '@') {
-                                /* @major,minor[-minor2] */
-                                /* (useful when name is ambiguous:
-                                 * "/sys/class/usb/lp0" and
-                                 * "/sys/class/printer/lp0") */
-                                int cmaj, cmin0, cmin1, sc;
-                                if (major < 0)
-                                        continue; /* no dev, no match */
-                                sc = sscanf(val, "@%u,%u-%u", &cmaj, &cmin0, &cmin1);
-                                if (sc < 1
-                                 || major != cmaj
-                                 || (sc == 2 && minor != cmin0)
-                                 || (sc == 3 && (minor < cmin0 || minor > cmin1))
-                                ) {
-                                        continue; /* this line doesn't match */
-                                }
-                                goto line_matches;
-                        }
-                        if (val[0] == '$') {
-                                /* regex to match an environment variable */
-                                char *eq = strchr(++val, '=');
-                                if (!eq)
-                                        continue;
-                                *eq = '\0';
-                                str_to_match = getenv(val);
-                                if (!str_to_match)
-                                        continue;
-                                str_to_match -= strlen(val) + 1;
-                                *eq = '=';
+                str_to_match = "";
+
+                rule = next_rule();
+
+#if ENABLE_FEATURE_MDEV_CONF
+                if (rule->maj >= 0) {  /* @maj,min rule */
+                        if (major != rule->maj)
+                                continue;
+                        if (minor < rule->min0 || minor > rule->min1)
+                                continue;
+                        memset(off, 0, sizeof(off));
+                        goto rule_matches;
+                }
+                if (rule->envvar) { /* $envvar=regex rule */
+                        str_to_match = getenv(rule->envvar);
+                        dbg("getenv('%s'):'%s'", rule->envvar, str_to_match);
+                        if (!str_to_match)
+                                continue;
+                } else {
+                        /* regex to match [subsystem/]device_name */
+                        str_to_match = (rule->regex_has_slash ? path : device_name);
+                }
+
+                if (rule->regex_compiled) {
+                        int regex_match = regexec(&rule->match, str_to_match, ARRAY_SIZE(off), off, 0);
+                        dbg("regex_match for '%s':%d", str_to_match, regex_match);
+                        //bb_error_msg("matches:");
+                        //for (int i = 0; i < ARRAY_SIZE(off); i++) {
+                        //      if (off[i].rm_so < 0) continue;
+                        //      bb_error_msg("match %d: '%.*s'\n", i,
+                        //              (int)(off[i].rm_eo - off[i].rm_so),
+                        //              device_name + off[i].rm_so);
+                        //}
+
+                        if (regex_match != 0
+                        /* regexec returns whole pattern as "range" 0 */
+                         || off[0].rm_so != 0
+                         || (int)off[0].rm_eo != (int)strlen(str_to_match)
+                        ) {
+                                continue; /* this rule doesn't match */
                         }
-                        /* else: regex to match [subsystem/]device_name */
-
-                        {
-                                regex_t match;
-                                int result;
-
-                                xregcomp(&match, val, REG_EXTENDED);
-                                result = regexec(&match, str_to_match, ARRAY_SIZE(off), off, 0);
-                                regfree(&match);
-                                //bb_error_msg("matches:");
-                                //for (int i = 0; i < ARRAY_SIZE(off); i++) {
-                                //      if (off[i].rm_so < 0) continue;
-                                //      bb_error_msg("match %d: '%.*s'\n", i,
-                                //              (int)(off[i].rm_eo - off[i].rm_so),
-                                //              device_name + off[i].rm_so);
-                                //}
-
-                                /* If no match, skip rest of line */
-                                /* (regexec returns whole pattern as "range" 0) */
-                                if (result
-                                 || off[0].rm_so
-                                 || ((int)off[0].rm_eo != (int)strlen(str_to_match))
-                                ) {
-                                        continue; /* this line doesn't match */
-                                }
+                }
+                /* else: it's final implicit "match-all" rule */
+#endif
+
+ rule_matches:
+                dbg("rule matched");
+
+                /* Build alias name */
+                alias = NULL;
+                if (ENABLE_FEATURE_MDEV_RENAME && rule->ren_mov) {
+                        aliaslink = rule->ren_mov[0];
+                        if (aliaslink == '!') {
+                                /* "!": suppress node creation/deletion */
+                                major = -2;
                         }
- line_matches:
-                        /* This line matches. Stop parsing after parsing
-                         * the rest the line unless keep_matching == 1 */
-
-                        /* 2nd field: uid:gid - device ownership */
-                        if (get_uidgid(&ugid, tokens[1], /*allow_numeric:*/ 1) == 0)
-                                bb_error_msg("unknown user/group %s on line %d", tokens[1], parser->lineno);
-
-                        /* 3rd field: mode - device permissions */
-                        bb_parse_mode(tokens[2], &mode);
-
-                        val = tokens[3];
-                        /* 4th field (opt): ">|=alias" or "!" to not create the node */
-
-                        if (ENABLE_FEATURE_MDEV_RENAME && val) {
-                                char *a, *s, *st;
-
-                                a = val;
-                                s = strchrnul(val, ' ');
-                                st = strchrnul(val, '\t');
-                                if (st < s)
-                                        s = st;
-                                st = (s[0] && s[1]) ? s+1 : NULL;
-
-                                aliaslink = a[0];
-                                if (aliaslink == '!' && s == a+1) {
-                                        val = st;
-                                        /* "!": suppress node creation/deletion */
-                                        major = -2;
-                                }
-                                else if (aliaslink == '>' || aliaslink == '=') {
-                                        val = st;
-                                        s[0] = '\0';
-                                        if (ENABLE_FEATURE_MDEV_RENAME_REGEXP) {
-                                                char *p;
-                                                unsigned i, n;
-
-                                                /* substitute %1..9 with off[1..9], if any */
-                                                n = 0;
-                                                s = a;
-                                                while (*s)
-                                                        if (*s++ == '%')
-                                                                n++;
-
-                                                p = alias = xzalloc(strlen(a) + n * strlen(str_to_match));
-                                                s = a + 1;
-                                                while (*s) {
-                                                        *p = *s;
-                                                        if ('%' == *s) {
-                                                                i = (s[1] - '0');
-                                                                if (i <= 9 && off[i].rm_so >= 0) {
-                                                                        n = off[i].rm_eo - off[i].rm_so;
-                                                                        strncpy(p, str_to_match + off[i].rm_so, n);
-                                                                        p += n - 1;
-                                                                        s++;
-                                                                }
+                        else if (aliaslink == '>' || aliaslink == '=') {
+                                if (ENABLE_FEATURE_MDEV_RENAME_REGEXP) {
+                                        char *s;
+                                        char *p;
+                                        unsigned n;
+
+                                        /* substitute %1..9 with off[1..9], if any */
+                                        n = 0;
+                                        s = rule->ren_mov;
+                                        while (*s)
+                                                if (*s++ == '%')
+                                                        n++;
+
+                                        p = alias = xzalloc(strlen(rule->ren_mov) + n * strlen(str_to_match));
+                                        s = rule->ren_mov + 1;
+                                        while (*s) {
+                                                *p = *s;
+                                                if ('%' == *s) {
+                                                        unsigned i = (s[1] - '0');
+                                                        if (i <= 9 && off[i].rm_so >= 0) {
+                                                                n = off[i].rm_eo - off[i].rm_so;
+                                                                strncpy(p, str_to_match + off[i].rm_so, n);
+                                                                p += n - 1;
+                                                                s++;
                                                         }
-                                                        p++;
-                                                        s++;
                                                 }
-                                        } else {
-                                                alias = xstrdup(a + 1);
+                                                p++;
+                                                s++;
                                         }
+                                } else {
+                                        alias = xstrdup(rule->ren_mov + 1);
                                 }
                         }
+                }
+                dbg("alias:'%s'", alias);
 
-                        if (ENABLE_FEATURE_MDEV_EXEC && val) {
-                                const char *s = "$@*";
-                                const char *s2 = strchr(s, val[0]);
-
-                                if (!s2) {
-                                        bb_error_msg("bad line %u", parser->lineno);
-                                        if (ENABLE_FEATURE_MDEV_RENAME)
-                                                free(alias);
-                                        continue;
-                                }
+                command = NULL;
+                IF_FEATURE_MDEV_EXEC(command = rule->r_cmd;)
+                if (command) {
+                        const char *s = "$@*";
+                        const char *s2 = strchr(s, command[0]);
 
-                                /* Are we running this command now?
-                                 * Run $cmd on delete, @cmd on create, *cmd on both
+                        /* Are we running this command now?
+                         * Run $cmd on delete, @cmd on create, *cmd on both
+                         */
+                        if (s2 - s != delete) {
+                                /* We are here if: '*',
+                                 * or: '@' and delete = 0,
+                                 * or: '$' and delete = 1
                                  */
-                                if (s2 - s != delete) {
-                                        /* We are here if: '*',
-                                         * or: '@' and delete = 0,
-                                         * or: '$' and delete = 1
-                                         */
-                                        command = xstrdup(val + 1);
-                                }
+                                command++;
+                        } else {
+                                command = NULL;
                         }
                 }
-
-                /* End of field parsing */
+                dbg("command:'%s'", command);
 
                 /* "Execute" the line we found */
-                {
-                        const char *node_name;
-
-                        node_name = device_name;
-                        if (ENABLE_FEATURE_MDEV_RENAME && alias)
-                                node_name = alias = build_alias(alias, device_name);
-
-                        if (!delete && major >= 0) {
-                                if (mknod(node_name, mode | type, makedev(major, minor)) && errno != EEXIST)
-                                        bb_perror_msg("can't create '%s'", node_name);
-                                if (major == G.root_major && minor == G.root_minor)
-                                        symlink(node_name, "root");
-                                if (ENABLE_FEATURE_MDEV_CONF) {
-                                        chmod(node_name, mode);
-                                        chown(node_name, ugid.uid, ugid.gid);
-                                }
-                                if (ENABLE_FEATURE_MDEV_RENAME && alias) {
-                                        if (aliaslink == '>')
-                                                symlink(node_name, device_name);
-                                }
-                        }
+                node_name = device_name;
+                if (ENABLE_FEATURE_MDEV_RENAME && alias) {
+                        node_name = alias = build_alias(alias, device_name);
+                        dbg("alias2:'%s'", alias);
+                }
 
-                        if (ENABLE_FEATURE_MDEV_EXEC && command) {
-                                /* setenv will leak memory, use putenv/unsetenv/free */
-                                char *s = xasprintf("%s=%s", "MDEV", node_name);
-                                char *s1 = xasprintf("%s=%s", "SUBSYSTEM", G.subsystem);
-                                putenv(s);
-                                putenv(s1);
-                                if (system(command) == -1)
-                                        bb_perror_msg("can't run '%s'", command);
-                                bb_unsetenv_and_free(s1);
-                                bb_unsetenv_and_free(s);
-                                free(command);
+                if (!delete && major >= 0) {
+                        dbg("mknod('%s',%o,(%d,%d))", node_name, rule->mode | type, major, minor);
+                        if (mknod(node_name, rule->mode | type, makedev(major, minor)) && errno != EEXIST)
+                                bb_perror_msg("can't create '%s'", node_name);
+                        if (major == G.root_major && minor == G.root_minor)
+                                symlink(node_name, "root");
+                        if (ENABLE_FEATURE_MDEV_CONF) {
+                                chmod(node_name, rule->mode);
+                                chown(node_name, rule->ugid.uid, rule->ugid.gid);
                         }
-
-                        if (delete && major >= -1) {
-                                if (ENABLE_FEATURE_MDEV_RENAME && alias) {
-                                        if (aliaslink == '>')
-                                                unlink(device_name);
-                                }
-                                unlink(node_name);
+                        if (ENABLE_FEATURE_MDEV_RENAME && alias) {
+                                if (aliaslink == '>')
+                                        symlink(node_name, device_name);
                         }
+                }
 
-                        if (ENABLE_FEATURE_MDEV_RENAME)
-                                free(alias);
+                if (ENABLE_FEATURE_MDEV_EXEC && command) {
+                        /* setenv will leak memory, use putenv/unsetenv/free */
+                        char *s = xasprintf("%s=%s", "MDEV", node_name);
+                        char *s1 = xasprintf("%s=%s", "SUBSYSTEM", G.subsystem);
+                        putenv(s);
+                        putenv(s1);
+                        if (system(command) == -1)
+                                bb_perror_msg("can't run '%s'", command);
+                        bb_unsetenv_and_free(s1);
+                        bb_unsetenv_and_free(s);
                 }
 
+                if (delete && major >= -1) {
+                        if (ENABLE_FEATURE_MDEV_RENAME && alias) {
+                                if (aliaslink == '>')
+                                        unlink(device_name);
+                        }
+                        unlink(node_name);
+                }
+
+                if (ENABLE_FEATURE_MDEV_RENAME)
+                        free(alias);
+
                 /* We found matching line.
-                 * Stop unless it was prefixed with '-' */
-                if (ENABLE_FEATURE_MDEV_CONF && !keep_matching)
+                 * Stop unless it was prefixed with '-'
+                 */
+                if (!ENABLE_FEATURE_MDEV_CONF || !rule->keep_matching)
                         break;
+        } /* for (;;) */
 
-        /* end of "while line is read from /etc/mdev.conf" */
-        } while (ENABLE_FEATURE_MDEV_CONF);
-
-        if (ENABLE_FEATURE_MDEV_CONF)
-                config_close(parser);
         free(subsystem_slash_devname);
 }
 
@@ -618,6 +734,10 @@ int mdev_main(int argc UNUSED_PARAM, char **argv)
 
         INIT_G();
 
+#if ENABLE_FEATURE_MDEV_CONF
+        G.filename = "/etc/mdev.conf";
+#endif
+
         /* We can be called as hotplug helper */
         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
         bb_sanitize_stdio();
@@ -633,6 +753,10 @@ int mdev_main(int argc UNUSED_PARAM, char **argv)
                  */
                 struct stat st;
 
+#if ENABLE_FEATURE_MDEV_CONF
+                /* Same as xrealloc_vector(NULL, 4, 0): */
+                G.rule_vec = xzalloc((1 << 4) * sizeof(*G.rule_vec));
+#endif
                 xstat("/", &st);
                 G.root_major = major(st.st_dev);
                 G.root_minor = minor(st.st_dev);