fix several problems with config parser:

 a bug where it underflows the string
 a bug where it never frees parser_t struct
make read_config() return 0 if parser is NULL,
 make config_close() accept and ignore NULL parser -
 eliminates many if() blocks
reverse the sense of parser bit flags - negative flags
 are harder to grok.
hexdump: revert the change to use config parser, it is BIGGER
 and also requires additional quirks in parser
*: explicitly use PARSER_NORMAL instead of 0

function                                             old     new   delta
login_main                                          1575    1596     +21
config_close                                          18      29     +11
bbunpack                                             383     391      +8
qgravechar                                           106     109      +3
rtnl_tab_initialize                                  121     117      -4
expand                                              1697    1693      -4
man_main                                             717     712      -5
nameif_main                                          674     668      -6
hexdump_main                                         597     591      -6
read_config                                          217     209      -8
dnsd_main                                           1478    1470      -8
sysctl_main                                          203     189     -14
config_open2                                          44      25     -19
make_device                                         1177    1141     -36
config_read                                          597     549     -48
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/11 up/down: 43/-158)         Total: -115 bytes

1 files changed, 13 insertions, 8 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 47fcdf08b..48cbd90c0 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -998,15 +998,20 @@ int bb_parse_mode(const char* s, mode_t* theMode) FAST_FUNC;
  * Config file parser
  */
 enum {
-        PARSE_VANILLA        = 0x00000000, // trim line, collapse delimiters, warn and continue if less than mintokens
-        PARSE_DONT_REDUCE    = 0x00010000, // do not treat consecutive delimiters as one
-        PARSE_DONT_TRIM      = 0x00020000, // do not trim line of leading and trailing delimiters
-        PARSE_LAST_IS_GREEDY = 0x00040000, // last token takes whole remainder of the line
-//      PARSE_DONT_NULL      = 0x00080000, // do not set tokens[] to NULL
-        PARSE_MIN_DIE        = 0x00100000, // die if less tokens found
+        PARSE_COLLAPSE  = 0x00010000, // treat consecutive delimiters as one
+        PARSE_TRIM      = 0x00020000, // trim leading and trailing delimiters
+// TODO: COLLAPSE and TRIM seem to always go in pair
+        PARSE_GREEDY    = 0x00040000, // last token takes entire remainder of the line
+        PARSE_MIN_DIE   = 0x00100000, // die if < min tokens found
         // keep a copy of current line
-        PARSE_KEEP_COPY      = 0x00200000 * ENABLE_DEBUG_CROND_OPTION,
-        PARSE_ESCAPE         = 0x00400000, // process escape sequences in tokens
+        PARSE_KEEP_COPY = 0x00200000 * ENABLE_DEBUG_CROND_OPTION,
+//      PARSE_ESCAPE    = 0x00400000, // process escape sequences in tokens
+        // NORMAL is:
+        // * remove leading and trailing delimiters and collapse
+        //   multiple delimiters into one
+        // * warn and continue if less than mintokens delimiters found
+        // * grab everything into last token
+        PARSE_NORMAL    = PARSE_COLLAPSE | PARSE_TRIM | PARSE_GREEDY,
 };
 typedef struct parser_t {
         FILE *fp;