ash: fix $IFS handling in read. closes bug 235

3 files changed, 37 insertions, 12 deletions

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." )