parse_config: use getline. BIG speedup with glibc (~40%).

function                                             old     new   delta
config_read                                          559     604     +45
getline                                                -      23     +23
config_close                                          29      49     +20
find_pair                                            169     187     +18
showmode                                             330     338      +8
hash_find                                            233     234      +1
builtin_umask                                        133     132      -1
lzo1x_optimize                                      1434    1429      -5
test_main                                            253     247      -6
buffer_fill_and_print                                196     179     -17
create_J                                            1849    1826     -23
config_free_data                                      37       -     -37
------------------------------------------------------------------------------
(add/remove: 3/1 grow/shrink: 5/5 up/down: 138/-89)            Total: 26 bytes

Signed-off-by: Timo Teras <timo.teras@iki.fi>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 45 insertions, 50 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 2cac7e60c..953bec334 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1184,8 +1184,9 @@ enum {
 };
 typedef struct parser_t {
         FILE *fp;
-        char *line;
         char *data;
+        char *line, *nline;
+        size_t line_alloc, nline_alloc;
         int lineno;
 } parser_t;
 parser_t* config_open(const char *filename) FAST_FUNC;
diff --git a/libbb/parse_config.c b/libbb/parse_config.c
index c0c34f312..cf5ba4deb 100644
--- a/libbb/parse_config.c
+++ b/libbb/parse_config.c
@@ -83,60 +83,55 @@ parser_t* FAST_FUNC config_open(const char *filename)
         return config_open2(filename, fopen_or_warn_stdin);
 }
 
-static void config_free_data(parser_t *parser)
-{
-        free(parser->line);
-        parser->line = NULL;
-        if (PARSE_KEEP_COPY) { /* compile-time constant */
-                free(parser->data);
-                parser->data = NULL;
-        }
-}
-
 void FAST_FUNC config_close(parser_t *parser)
 {
         if (parser) {
-                config_free_data(parser);
+                if (PARSE_KEEP_COPY) /* compile-time constant */
+                        free(parser->data);
                 fclose(parser->fp);
+                free(parser->line);
+                free(parser->nline);
                 free(parser);
         }
 }
 
-/* This function reads an entire line from a text file, up to a newline
- * or NUL byte, exclusive.  It returns a malloc'ed char*.
- * *lineno is incremented for each line.
+/* This function reads an entire line from a text file,
+ * up to a newline, exclusive.
  * Trailing '\' is recognized as line continuation.
- * Returns NULL if EOF/error.
+ * Returns -1 if EOF/error.
  */
-static char* get_line_with_continuation(FILE *file, int *lineno)
+static int get_line_with_continuation(parser_t *parser)
 {
-        int ch;
-        unsigned idx = 0;
-        char *linebuf = NULL;
-
-        while ((ch = getc(file)) != EOF) {
-                /* grow the line buffer as necessary */
-                if (!(idx & 0xff))
-                        linebuf = xrealloc(linebuf, idx + 0x101);
-                if (ch == '\n')
-                        ch = '\0';
-                linebuf[idx] = (char) ch;
-                if (ch == '\0') {
-                        (*lineno)++;
-                        if (idx == 0 || linebuf[idx-1] != '\\')
-                                break;
-                        idx--; /* go back to '/' */
-                        continue;
+        ssize_t len, nlen;
+        char *line;
+
+        len = getline(&parser->line, &parser->line_alloc, parser->fp);
+        if (len <= 0)
+                return len;
+
+        line = parser->line;
+        for (;;) {
+                parser->lineno++;
+                if (line[len - 1] == '\n')
+                        len--;
+                if (len == 0 || line[len - 1] != '\\')
+                        break;
+                len--;
+
+                nlen = getline(&parser->nline, &parser->nline_alloc, parser->fp);
+                if (nlen <= 0)
+                        break;
+
+                if (parser->line_alloc < len + nlen + 1) {
+                        parser->line_alloc = len + nlen + 1;
+                        line = parser->line = xrealloc(line, parser->line_alloc);
                 }
-                idx++;
-        }
-        if (ch == EOF) {
-                /* handle corner case when the file is not ended with '\n' */
-                (*lineno)++;
-                if (linebuf)
-                        linebuf[idx] = '\0';
+                memcpy(&line[len], parser->nline, nlen);
+                len += nlen;
         }
-        return linebuf;
+
+        line[len] = '\0';
+        return len;
 }
 
 
@@ -176,15 +171,14 @@ int FAST_FUNC config_read(parser_t *parser, char **tokens, unsigned flags, const
         ntokens = (uint8_t)flags;
         mintokens = (uint8_t)(flags >> 8);
 
-again:
+ again:
         memset(tokens, 0, sizeof(tokens[0]) * ntokens);
-        config_free_data(parser);
 
         /* Read one line (handling continuations with backslash) */
-        line = get_line_with_continuation(parser->fp, &parser->lineno);
-        if (line == NULL)
+        if (get_line_with_continuation(parser) < 0)
                 return 0;
-        parser->line = line;
+
+        line = parser->line;
 
         /* Skip token in the start of line? */
         if (flags & PARSE_TRIM)
@@ -193,8 +187,10 @@ again:
         if (line[0] == '\0' || line[0] == delims[0])
                 goto again;
 
-        if (flags & PARSE_KEEP_COPY)
+        if (flags & PARSE_KEEP_COPY) {
+                free(parser->data);
                 parser->data = xstrdup(line);
+        }
 
         /* Tokenize the line */
         t = 0;
@@ -240,8 +236,6 @@ again:
                                 parser->lineno, t, mintokens);
                 if (flags & PARSE_MIN_DIE)
                         xfunc_die();
-                if (flags & PARSE_KEEP_COPY)
-                        free(parser->data);
                 goto again;
         }