- fix segfault in nameif with mactab file

  (by fixing and shrink config parser)

function                                             old     new   delta
config_free_data                                       -      37     +37
config_open                                           43      48      +5
pack_gzip                                           1658    1660      +2
nameif_main                                          527     525      -2
SynchronizeFile                                      629     623      -6
make_device                                         1184    1176      -8
config_close                                          31      18     -13
config_read                                          431     393     -38
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/5 up/down: 44/-67)            Total: -23 bytes

1 files changed, 42 insertions, 43 deletions

diff --git a/libbb/parse_config.c b/libbb/parse_config.c
index f07099285..70f933fe3 100644
--- a/libbb/parse_config.c
+++ b/libbb/parse_config.c
@@ -31,44 +31,42 @@ Typical usage:
 
 */
 
-FILE* FAST_FUNC config_open(parser_t *parser, const char *filename)
+parser_t* FAST_FUNC config_open(const char *filename)
 {
-        // empty file configures nothing!
+        parser_t *parser = xzalloc(sizeof(parser_t));
+        /* empty file configures nothing */
         parser->fp = fopen_or_warn(filename, "r");
-        if (!parser->fp)
-                return parser->fp;
-
-        // init parser
-        parser->line = NULL;
-        parser->lineno = 0;
-
-        return parser->fp;
+        if (parser->fp)
+                return parser;
+        config_close (parser);
+        if (ENABLE_FEATURE_CLEAN_UP)
+          free(parser);
+        return NULL;
 }
 
-void FAST_FUNC config_close(parser_t *parser)
+static void config_free_data(parser_t *const parser)
 {
         free(parser->line);
         free(parser->data);
+        parser->line = parser->data = NULL;
+}
+void FAST_FUNC config_close(parser_t *parser)
+{
+        config_free_data(parser);
         fclose(parser->fp);
 }
 
-int FAST_FUNC config_read(parser_t *parser, char **tokens, int ntokens, int mintokens, const char *delims, char comment)
+int FAST_FUNC config_read(parser_t *parser, char **tokens, int ntokens, int mintokens, const char*delims,char comment)
 {
         char *line, *q;
-        int token_num, len;
-        int noreduce = (ntokens < 0); // do not treat subsequent delimiters as one delimiter
-
-        if (ntokens < 0)
+        int ii;
+        /* do not treat subsequent delimiters as one delimiter */
+        bool noreduce = (ntokens < 0);
+        if (noreduce)
                 ntokens = -ntokens;
 
-        // nullify tokens
         memset(tokens, 0, sizeof(void *) * ntokens);
-
-        // free used line
-        free(parser->line);
-        parser->line = NULL;
-        free(parser->data);
-        parser->data = NULL;
+        config_free_data(parser);
 
         while (1) {
                 int n;
@@ -82,13 +80,13 @@ int FAST_FUNC config_read(parser_t *parser, char **tokens, int ntokens, int mint
                 parser->lineno++;
                 // handle continuations. Tito's code stolen :)
                 while (1) {
-                        len = strlen(line);
-                        if (!len)
-                                goto free_and_cont;
-                        if (line[len - 1] != '\\')
+                        ii = strlen(line);
+                        if (!ii)
+                                goto next_line;
+                        if (line[ii - 1] != '\\')
                                 break;
                         // multi-line object
-                        line[--len] = '\0';
+                        line[--ii] = '\0';
 //TODO: add xmalloc_fgetline-like iface but with appending to existing str
                         q = xmalloc_fgetline(parser->fp);
                         if (q) {
@@ -101,34 +99,35 @@ int FAST_FUNC config_read(parser_t *parser, char **tokens, int ntokens, int mint
                 if (comment) {
                         q = strchrnul(line, comment);
                         *q = '\0';
-                        len = q - line;
+                        ii = q - line;
                 }
                 // skip leading delimiters
                 n = strspn(line, delims);
                 if (n) {
-                        len -= n;
+                        ii -= n;
                         strcpy(line, line + n);
                 }
-                if (len)
+                if (ii)
                         break;
-                // skip empty lines
- free_and_cont:
+
+ next_line:
+                /* skip empty line */
                 free(line);
         }
 
         // non-empty line found, parse and return
 
         // store line
-        parser->line = line = xrealloc(line, len + 1);
+        parser->line = line = xrealloc(line, ii + 1);
         parser->data = xstrdup(line);
 
         // now split line to tokens
 //TODO: discard consecutive delimiters?
-        token_num = 0;
+        ii = 0;
         ntokens--; // now it's max allowed token no
         while (1) {
                 // get next token
-                if (token_num == ntokens)
+                if (ii == ntokens)
                         break;
                 q = line + strcspn(line, delims);
                 if (!*q)
@@ -136,20 +135,20 @@ int FAST_FUNC config_read(parser_t *parser, char **tokens, int ntokens, int mint
                 // pin token
                 *q++ = '\0';
                 if (noreduce || *line) {
-                        tokens[token_num++] = line;
-//bb_error_msg("L[%d] T[%s]", token_num, line);
+                        tokens[ii++] = line;
+//bb_info_msg("L[%d] T[%s]\n", ii, line);
                 }
                 line = q;
-        }
+        }
 
         // non-empty remainder is also a token,
         // so if ntokens <= 1, we just return the whole line
         if (noreduce || *line)
-                tokens[token_num++] = line;
+                tokens[ii++] = line;
 
-        if (token_num < mintokens)
+        if (ii < mintokens)
                 bb_error_msg_and_die("bad line %u: %d tokens found, %d needed",
-                                parser->lineno, token_num, mintokens);
+                                parser->lineno, ii, mintokens);
 
-        return token_num;
+        return ii;
 }