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 9be1068..a98dd35 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)
 {