From 46aeab9a349d097307a87d7dfde3057f9e4e6722 Mon Sep 17 00:00:00 2001
From: Denis Vlasenko <vda.linux@googlemail.com>
Date: Tue, 31 Mar 2009 19:18:17 +0000
Subject: [PATCH] ash: fix $IFS handling in read. closes bug 235

---
 shell/ash.c                            | 35 +++++++++++++++++---------
 shell/ash_test/ash-read/read_ifs.right |  7 ++++++
 shell/ash_test/ash-read/read_ifs.tests |  7 ++++++
 3 files changed, 37 insertions(+), 12 deletions(-)
 create mode 100644 shell/ash_test/ash-read/read_ifs.right
 create mode 100755 shell/ash_test/ash-read/read_ifs.tests

diff --git a/shell/ash.c b/shell/ash.c
index 13b4329b5..1de989ef3 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -12574,7 +12574,7 @@ readcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 #endif
 
 	status = 0;
-	startword = 1;
+	startword = 2;
 	backslash = 0;
 #if ENABLE_ASH_READ_TIMEOUT
 	if (timeout) /* NB: ensuring end_ms is nonzero */
@@ -12582,6 +12582,8 @@ readcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 #endif
 	STARTSTACKSTR(p);
 	do {
+		const char *is_ifs;
+
 #if ENABLE_ASH_READ_TIMEOUT
 		if (end_ms) {
 			struct pollfd pfd[1];
@@ -12611,25 +12613,34 @@ readcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 			continue;
 		}
 		if (!rflag && c == '\\') {
-			backslash++;
+			backslash = 1;
 			continue;
 		}
 		if (c == '\n')
 			break;
-		if (startword && *ifs == ' ' && strchr(ifs, c)) {
-			continue;
+		is_ifs = strchr(ifs, c);
+		if (startword && is_ifs) {
+			if (isspace(c))
+				continue;
+			/* non-space ifs char */
+			startword--;
+			if (startword == 1) /* first one? */
+				continue;
 		}
 		startword = 0;
-		if (ap[1] != NULL && strchr(ifs, c) != NULL) {
+		if (ap[1] != NULL && is_ifs) {
+			const char *beg;
 			STACKSTRNUL(p);
-			setvar(*ap, stackblock(), 0);
+			beg = stackblock();
+			setvar(*ap, beg, 0);
 			ap++;
-			startword = 1;
+			/* can we skip one non-space ifs? (2: yes) */
+			startword = isspace(c) ? 2 : 1;
 			STARTSTACKSTR(p);
-		} else {
- put:
-			STPUTC(c, p);
+			continue;
 		}
+ put:
+		STPUTC(c, p);
 	}
 /* end of do {} while: */
 #if ENABLE_ASH_READ_NCHARS
@@ -12643,8 +12654,8 @@ readcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 #endif
 
 	STACKSTRNUL(p);
-	/* Remove trailing blanks */
-	while ((char *)stackblock() <= --p && strchr(ifs, *p) != NULL)
+	/* Remove trailing space ifs chars */
+	while ((char *)stackblock() <= --p && isspace(*p) && strchr(ifs, *p) != NULL)
 		*p = '\0';
 	setvar(*ap, stackblock(), 0);
 	while (*++ap != NULL)
diff --git a/shell/ash_test/ash-read/read_ifs.right b/shell/ash_test/ash-read/read_ifs.right
new file mode 100644
index 000000000..027ecd18f
--- /dev/null
+++ b/shell/ash_test/ash-read/read_ifs.right
@@ -0,0 +1,7 @@
+.a. .b. .c.
+.a. .b. .c.
+.a. .. .b,c.
+.a. .. .b,c.
+.a. .. .c.
+.a. .. .c. .d.
+.a. .. .b,c,d  ,  ,.
diff --git a/shell/ash_test/ash-read/read_ifs.tests b/shell/ash_test/ash-read/read_ifs.tests
new file mode 100755
index 000000000..cf7cd934c
--- /dev/null
+++ b/shell/ash_test/ash-read/read_ifs.tests
@@ -0,0 +1,7 @@
+printf 'a\t\tb\tc\n' | ( IFS=$(printf "\t") read a b c; echo ".$a. .$b. .$c." )
+printf 'a\t\tb\tc\n' | ( IFS=$(printf " \t") read a b c; echo ".$a. .$b. .$c." )
+printf 'a,,b,c\n'    | ( IFS="," read a b c; echo ".$a. .$b. .$c." )
+printf 'a,,b,c\n'    | ( IFS=" ," read a b c; echo ".$a. .$b. .$c." )
+printf 'a ,, c\n'    | ( IFS=" ," read a b c; echo ".$a. .$b. .$c." )
+printf 'a ,, c d\n'  | ( IFS=" ," read a b c d; echo ".$a. .$b. .$c. .$d." )
+printf ' a,,b,c,d  ,  ,\n' | ( IFS=" ," read a b c; echo ".$a. .$b. .$c." )
-- 
2.25.1