libbb: split bb_get_chunk_from_file and bb_get_chunk_with_continuation

This also moves bb_get_chunk_with_continuation into its sole user,
parse_config.c.
This allows to optimize both functions separately,
they need to be optimized for speed.
(this need was highlighted by slow modprobe caused in part by slow
bb_get_chunk_with_continuation in config parser).

function                                             old     new   delta
bb_get_chunk_from_file                                 7     130    +123
config_read                                          457     558    +101
bb_get_chunk_with_continuation                       194       -    -194
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 2/0 up/down: 224/-194)           Total: 30 bytes

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

1 files changed, 8 insertions, 34 deletions

diff --git a/libbb/get_line_from_file.c b/libbb/get_line_from_file.c
index 9be10687b..a98dd35eb 100644
--- a/libbb/get_line_from_file.c
+++ b/libbb/get_line_from_file.c
@@ -11,45 +11,24 @@
 
 #include "libbb.h"
 
-/* This function reads an entire line from a text file, up to a newline
- * or NUL byte, inclusive.  It returns a malloc'ed char * which
- * must be free'ed by the caller.  If end is NULL '\n' isn't considered
- * end of line.  If end isn't NULL, length of the chunk is stored in it.
- * If lineno is not NULL, *lineno is incremented for each line,
- * and also trailing '\' is recognized as line continuation.
- *
- * Returns NULL if EOF/error. */
-char* FAST_FUNC bb_get_chunk_with_continuation(FILE *file, int *end, int *lineno)
+char* FAST_FUNC bb_get_chunk_from_file(FILE *file, int *end)
 {
         int ch;
-        int idx = 0;
+        unsigned idx = 0;
         char *linebuf = NULL;
-        int linebufsz = 0;
 
         while ((ch = getc(file)) != EOF) {
                 /* grow the line buffer as necessary */
-                if (idx >= linebufsz) {
-                        linebufsz += 256;
-                        linebuf = xrealloc(linebuf, linebufsz);
-                }
+                if (!(idx & 0xff))
+                        linebuf = xrealloc(linebuf, idx + 0x100);
                 linebuf[idx++] = (char) ch;
-                if (!ch)
+                if (ch == '\0')
+                        break;
+                if (end && ch == '\n')
                         break;
-                if (end && ch == '\n') {
-                        if (lineno == NULL)
-                                break;
-                        (*lineno)++;
-                        if (idx < 2 || linebuf[idx-2] != '\\')
-                                break;
-                        idx -= 2;
-                }
         }
-        if (end) {
+        if (end)
                 *end = idx;
-                /* handle corner case when the file is not ended with '\n' */
-                if (ch == EOF && lineno != NULL)
-                        (*lineno)++;
-        }
         if (linebuf) {
                 // huh, does fgets discard prior data on error like this?
                 // I don't think so....
@@ -63,11 +42,6 @@ char* FAST_FUNC bb_get_chunk_with_continuation(FILE *file, int *end, int *lineno
         return linebuf;
 }
 
-char* FAST_FUNC bb_get_chunk_from_file(FILE *file, int *end)
-{
-        return bb_get_chunk_with_continuation(file, end, NULL);
-}
-
 /* Get line, including trailing \n if any */
 char* FAST_FUNC xmalloc_fgets(FILE *file)
 {