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3b4d04b77

Denys Vlasenko

2016-09-29

SUCCESS Duration: 202s

Subject

ash: input: Allow two consecutive calls to pungetc

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

shell/ash.c +43 -34

shell/ash.c+43 -34

@@ -1168,6 +1168,12 @@ struct strpush {
	struct alias ap; / if push was associated with an alias */
	#endif
	char string; / remember the string since it may change */
+
+	/* Remember last two characters for pungetc. */
+	int lastc[2];
+
+	/* Number of outstanding calls to pungetc. */
+	int unget;
	};

	struct parsefile {
@@ -1180,6 +1186,12 @@ struct parsefile {
	char buf; / input buffer */
	struct strpush strpush; / for pushing strings at this level */
	struct strpush basestrpush; /* so pushing one is fast */
+
+	/* Remember last two characters for pungetc. */
+	int lastc[2];
+
+	/* Number of outstanding calls to pungetc. */
+	int unget;
	};

	static struct parsefile basepf; /* top level input file */
@@ -9715,6 +9727,8 @@ pushstring(char s, struct alias ap)
	g_parsefile->strpush = sp;
	sp->prev_string = g_parsefile->next_to_pgetc;
	sp->prev_left_in_line = g_parsefile->left_in_line;
+	sp->unget = g_parsefile->unget;
+	memcpy(sp->lastc, g_parsefile->lastc, sizeof(sp->lastc));
	#if ENABLE_ASH_ALIAS
	sp->ap = ap;
	if (ap) {
@@ -9724,6 +9738,7 @@ pushstring(char s, struct alias ap)
	#endif
	g_parsefile->next_to_pgetc = s;
	g_parsefile->left_in_line = len;
+	g_parsefile->unget = 0;
	INT_ON;
	}

@@ -9751,6 +9766,8 @@ popstring(void)
	#endif
	g_parsefile->next_to_pgetc = sp->prev_string;
	g_parsefile->left_in_line = sp->prev_left_in_line;
+	g_parsefile->unget = sp->unget;
+	memcpy(g_parsefile->lastc, sp->lastc, sizeof(sp->lastc));
	g_parsefile->strpush = sp->prev;
	if (sp != &(g_parsefile->basestrpush))
	free(sp);
@@ -9846,13 +9863,14 @@ preadfd(void)
	*/
	//#define pgetc_debug(...) bb_error_msg(__VA_ARGS__)
	#define pgetc_debug(...) ((void)0)
+	static int pgetc(void);
	static int
	preadbuffer(void)
	{
	char *q;
	int more;

-	while (g_parsefile->strpush) {
+	if (g_parsefile->strpush) {
	#if ENABLE_ASH_ALIAS
	if (g_parsefile->left_in_line == -1
	&& g_parsefile->strpush->ap
@@ -9864,13 +9882,7 @@ preadbuffer(void)
	}
	#endif
	popstring();
-	/* try "pgetc" now: */
-	pgetc_debug("preadbuffer internal pgetc at %d:%p'%s'",
-	g_parsefile->left_in_line,
-	g_parsefile->next_to_pgetc,
-	g_parsefile->next_to_pgetc);
-	if (--g_parsefile->left_in_line >= 0)
-	return (unsigned char)(*g_parsefile->next_to_pgetc++);
+	return pgetc();
	}
	/* on both branches above g_parsefile->left_in_line < 0.
	* "pgetc" needs refilling.
@@ -9949,27 +9961,28 @@ preadbuffer(void)
	return (unsigned char)*g_parsefile->next_to_pgetc++;
	}

-	#define pgetc_as_macro() \
-	(--g_parsefile->left_in_line >= 0 \
-	? (unsigned char)*g_parsefile->next_to_pgetc++ \
-	: preadbuffer() \
-	)
-
	static int
	pgetc(void)
	{
-	pgetc_debug("pgetc_fast at %d:%p'%s'",
+	int c;
+
+	pgetc_debug("pgetc at %d:%p'%s'",
	g_parsefile->left_in_line,
	g_parsefile->next_to_pgetc,
	g_parsefile->next_to_pgetc);
-	return pgetc_as_macro();
-	}
+	if (g_parsefile->unget)
+	return g_parsefile->lastc[--g_parsefile->unget];

-	#if ENABLE_ASH_OPTIMIZE_FOR_SIZE
-	# define pgetc_fast() pgetc()
-	#else
-	# define pgetc_fast() pgetc_as_macro()
-	#endif
+	if (--g_parsefile->left_in_line >= 0)
+	c = (signed char)*g_parsefile->next_to_pgetc++;
+	else
+	c = preadbuffer();
+
+	g_parsefile->lastc[1] = g_parsefile->lastc[0];
+	g_parsefile->lastc[0] = c;
+
+	return c;
+	}

	#if ENABLE_ASH_ALIAS
	static int
@@ -9977,11 +9990,11 @@ pgetc_without_PEOA(void)
	{
	int c;
	do {
-	pgetc_debug("pgetc_fast at %d:%p'%s'",
+	pgetc_debug("pgetc at %d:%p'%s'",
	g_parsefile->left_in_line,
	g_parsefile->next_to_pgetc,
	g_parsefile->next_to_pgetc);
-	c = pgetc_fast();
+	c = pgetc();
	} while (c == PEOA);
	return c;
	}
@@ -10015,18 +10028,13 @@ pfgets(char *line, int len)
	}

	/*
-	* Undo the last call to pgetc. Only one character may be pushed back.
+	* Undo a call to pgetc. Only two characters may be pushed back.
	* PEOF may be pushed back.
	*/
	static void
	pungetc(void)
	{
-	g_parsefile->left_in_line++;
-	g_parsefile->next_to_pgetc--;
-	pgetc_debug("pushed back to %d:%p'%s'",
-	g_parsefile->left_in_line,
-	g_parsefile->next_to_pgetc,
-	g_parsefile->next_to_pgetc);
+	g_parsefile->unget++;
	}

	/*
@@ -10043,6 +10051,7 @@ pushfile(void)
	pf->pf_fd = -1;
	/pf->strpush = NULL; - ckzalloc did it /
	/pf->basestrpush.prev = NULL;/
+	/pf->unget = 0;/
	g_parsefile = pf;
	}

@@ -11451,7 +11460,7 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
	IF_ASH_ALIAS(if (c != PEOA))
	USTPUTC(c, out);
	}
-	c = pgetc_fast();
+	c = pgetc();
	} /* for (;;) */
	endword:

@@ -11945,7 +11954,7 @@ xxreadtoken(void)
	setprompt_if(needprompt, 2);
	startlinno = g_parsefile->linno;
	for (;;) { /* until token or start of word found */
-	c = pgetc_fast();
+	c = pgetc();
	if (c == ' ' \|\| c == '\t' IF_ASH_ALIAS( \|\| c == PEOA))
	continue;

@@ -12008,7 +12017,7 @@ xxreadtoken(void)
	setprompt_if(needprompt, 2);
	startlinno = g_parsefile->linno;
	for (;;) { /* until token or start of word found */
-	c = pgetc_fast();
+	c = pgetc();
	switch (c) {
	case ' ': case '\t':
	IF_ASH_ALIAS(case PEOA:)