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>
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') {
- if (lineno == NULL)
- break;
- (*lineno)++;
- if (idx < 2 || linebuf[idx-2] != '\\')
- break;
- idx -= 2;
- }
+ if (end && ch == '\n')
+ break;
}
- 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 @@
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)
{
diff --git a/libbb/parse_config.c b/libbb/parse_config.c
index 4b02360..769ae51 100644
--- a/libbb/parse_config.c
+++ b/libbb/parse_config.c
@@ -104,6 +104,44 @@
}
}
+/* 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.
+ * Trailing '\' is recognized as line continuation.
+ * Returns NULL if EOF/error.
+ */
+static char* get_line_with_continuation(FILE *file, int *lineno)
+{
+ 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;
+ }
+ idx++;
+ }
+ if (ch == EOF) {
+ /* handle corner case when the file is not ended with '\n' */
+ (*lineno)++;
+ if (linebuf)
+ linebuf[idx] = '\0';
+ }
+ return linebuf;
+}
+
+
/*
0. If parser is NULL return 0.
1. Read a line from config file. If nothing to read then return 0.
@@ -132,28 +170,24 @@
{
char *line;
int ntokens, mintokens;
- int t, len;
+ int t;
+
+ if (!parser)
+ return 0;
ntokens = (uint8_t)flags;
mintokens = (uint8_t)(flags >> 8);
- if (parser == NULL)
- return 0;
-
again:
memset(tokens, 0, sizeof(tokens[0]) * ntokens);
config_free_data(parser);
/* Read one line (handling continuations with backslash) */
- line = bb_get_chunk_with_continuation(parser->fp, &len, &parser->lineno);
+ line = get_line_with_continuation(parser->fp, &parser->lineno);
if (line == NULL)
return 0;
parser->line = line;
- /* Strip trailing line-feed if any */
- if (len && line[len-1] == '\n')
- line[len-1] = '\0';
-
/* Skip token in the start of line? */
if (flags & PARSE_TRIM)
line += strspn(line, delims + 1);