libbb: unified config parser (By Vladimir Dronnikov)

mdev: use it

function                                             old     new   delta
config_read                                            -     400    +400
config_open                                            -      43     +43
config_close                                           -       9      +9
qrealloc                                              33      36      +3
compare_keys                                         735     737      +2
xstrtoull_range_sfx                                  296     295      -1
qgravechar                                           109     106      -3
get_address                                          181     178      -3
next_token                                           928     923      -5
sv_main                                             1228    1222      -6
find_main                                            418     406     -12
next_field                                            32       -     -32
make_device                                         1269    1184     -85
------------------------------------------------------------------------------
(add/remove: 3/1 grow/shrink: 2/7 up/down: 457/-147)          Total: 310 bytes

2 files changed, 248 insertions, 0 deletions

diff --git a/libbb/Kbuild b/libbb/Kbuild
index ab85ffc9e..726200675 100644
--- a/libbb/Kbuild
+++ b/libbb/Kbuild
@@ -63,6 +63,7 @@ lib-y += mode_string.o
 lib-y += mtab_file.o
 lib-y += obscure.o
 lib-y += parse_mode.o
+lib-y += parse_config.o
 lib-y += perror_msg.o
 lib-y += perror_msg_and_die.o
 lib-y += perror_nomsg.o
diff --git a/libbb/parse_config.c b/libbb/parse_config.c
new file mode 100644
index 000000000..6612db367
--- /dev/null
+++ b/libbb/parse_config.c
@@ -0,0 +1,247 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * config file parser helper
+ *
+ * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
+#include "libbb.h"
+
+/*
+
+Typical usage:
+
+----- CUT -----
+        char *t[3];     // tokens placeholder
+        parser_t p;     // parser structure
+        // open file
+        if (config_open(filename, &p)) {
+                // parse line-by-line
+                while (*config_read(&p, t, 3, 0, delimiters, comment_char)) { // 0..3 tokens
+                        // use tokens
+                        bb_error_msg("TOKENS: [%s][%s][%s]", t[0], t[1], t[2]);
+                }
+                ...
+                // free parser
+                config_close(&p);
+        }
+----- CUT -----
+
+*/
+
+#if !PARSER_STDIO_BASED
+
+char* FAST_FUNC config_open(parser_t *parser, const char *filename)
+{
+        // empty file configures nothing!
+        char *data = xmalloc_open_read_close(filename, NULL);
+        if (!data)
+                return data;
+
+        // convert 0x5c 0x0a (backslashes at the very end of line) to 0x20 0x20 (spaces)
+        for (char *s = data; (s = strchr(s, '\\')) != NULL; ++s)
+                if ('\n' == s[1]) {
+                        s[0] = s[1] = ' ';
+                }
+
+        // init parser
+        parser->line = parser->data = data;
+        parser->lineno = 0;
+
+        return data;
+}
+
+void FAST_FUNC config_close(parser_t *parser)
+{
+        // for now just free config data
+        free(parser->data);
+}
+
+char* FAST_FUNC config_read(parser_t *parser, char **tokens, int ntokens, int mintokens, const char *delims, char comment)
+{
+        char *ret, *line;
+        int noreduce = (ntokens<0); // do not treat subsequent delimiters as one delimiter
+        if (ntokens < 0)
+                ntokens = -ntokens;
+        ret = line = parser->line;
+        // nullify tokens
+        memset(tokens, 0, sizeof(void *) * ntokens);
+        // now split to lines
+        while (*line) {
+                int token_num = 0;
+                // limit the line
+                char *ptr = strchrnul(line, '\n');
+                *ptr++ = '\0';
+                // line number
+                parser->lineno++;
+                // comments mean EOLs
+                if (comment)
+                        *strchrnul(line, comment) = '\0';
+                // skip leading delimiters
+                while (*line && strchr(delims, *line))
+                        line++;
+                // skip empty lines
+                if (*line) {
+                        char *s;
+                        // now split line to tokens
+                        s = line;
+                        while (s) {
+                                char *p;
+                                // get next token
+                                if (token_num+1 >= ntokens)
+                                        break;
+                                p = s;
+                                while (*p && !strchr(delims, *p))
+                                        p++;
+                                if (!*p)
+                                        break;
+                                *p++ = '\0';
+                                // pin token
+                                if (noreduce || *s) {
+                                        tokens[token_num++] = s;
+//bb_error_msg("L[%d] T[%s]", token_num, s);
+                                }
+                                s = p;
+                        }
+                        // non-empty remainder is also a token. So if ntokens == 0, we just return the whole line
+                        if (s && (noreduce || *s))
+                                tokens[token_num++] = s;
+                        // sanity check: have we got all required tokens?
+                        if (token_num < mintokens)
+                                bb_error_msg_and_die("bad line %u, %d tokens found, %d needed", parser->lineno, token_num, mintokens);
+                        // advance data for the next call
+                        line = ptr;
+                        break;
+                }
+                // line didn't contain any token -> try next line
+                ret = line = ptr;
+        }
+        parser->line = line;
+
+        // return current line. caller must check *ret to determine whether to continue
+        return ret;
+}
+
+#else // stdio-based
+
+FILE* FAST_FUNC config_open(parser_t *parser, const char *filename)
+{
+        // 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;
+}
+
+void FAST_FUNC config_close(parser_t *parser)
+{
+        fclose(parser->fp);
+}
+
+char* 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)
+                ntokens = -ntokens;
+
+        // nullify tokens
+        memset(tokens, 0, sizeof(void *) * ntokens);
+
+        // free used line
+        free(parser->line);
+        parser->line = NULL;
+
+        while (1) {
+                int n;
+
+                // get fresh line
+//TODO: speed up xmalloc_fgetline by internally using fgets, not fgetc
+                line = xmalloc_fgetline(parser->fp);
+                if (!line)
+                        return line;
+
+                parser->lineno++;
+                // handle continuations. Tito's code stolen :)
+                while (1) {
+                        len = strlen(line);
+                        if (!len)
+                                goto free_and_cont;
+                        if (line[len - 1] != '\\')
+                                break;
+                        // multi-line object
+                        line[--len] = '\0';
+//TODO: add xmalloc_fgetline-like iface but with appending to existing str
+                        q = xmalloc_fgetline(parser->fp);
+                        if (q) {
+                                parser->lineno++;
+                                line = xasprintf("%s%s", line, q);
+                                free(q);
+                        }
+                }
+                // comments mean EOLs
+                if (comment) {
+                        q = strchrnul(line, comment);
+                        *q = '\0';
+                        len = q - line;
+                }
+                // skip leading delimiters
+                n = strspn(line, delims);
+                if (n) {
+                        len -= n;
+                        strcpy(line, line + n);
+                }
+                if (len)
+                        break;
+                // skip empty lines
+ free_and_cont:
+                free(line);
+        }
+
+        // non-empty line found, parse and return
+
+        // store line
+        parser->line = line = xrealloc(line, len + 1);
+
+        // now split line to tokens
+//TODO: discard consecutive delimiters?
+        token_num = 0;
+        ntokens--; // now it's max allowed token no
+        while (1) {
+                // get next token
+                if (token_num == ntokens)
+                        break;
+                q = line + strcspn(line, delims);
+                if (!*q)
+                        break;
+                // pin token
+                *q++ = '\0';
+                if (noreduce || *line) {
+                        tokens[token_num++] = line;
+//bb_error_msg("L[%d] T[%s]", token_num, 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;
+
+        if (token_num < mintokens)
+                bb_error_msg_and_die("bad line %u: %d tokens found, %d needed",
+                                parser->lineno, token_num, mintokens);
+
+        return parser->line; // maybe token_num instead?
+}
+
+#endif