3 files changed, 73 insertions, 17 deletions

diff --git a/shell/ash.c b/shell/ash.c
index eb5156bea..aaf0561b8 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -6612,7 +6612,6 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
         char *loc;
         char *rmesc, *rmescend;
         char *str;
-        IF_BASH_SUBSTR(int pos, len, orig_len;)
         int amount, resetloc;
         IF_BASH_PATTERN_SUBST(int workloc;)
         IF_BASH_PATTERN_SUBST(char *repl = NULL;)
@@ -6641,14 +6640,23 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
                 /* NOTREACHED */
 
 #if BASH_SUBSTR
-        case VSSUBSTR:
-//TODO: support more general format ${v:EXPR:EXPR},
-// where EXPR follows $(()) rules
+        case VSSUBSTR: {
+                int pos, len, orig_len;
+                char *colon;
+
                 loc = str = stackblock() + strloc;
+
+# if !ENABLE_FEATURE_SH_MATH
+#  define ash_arith number
+# endif
                 /* Read POS in ${var:POS:LEN} */
-                pos = atoi(loc); /* number(loc) errors out on "1:4" */
-                len = str - startp - 1;
+                colon = strchr(loc, ':');
+                if (colon) *colon = '\0';
+                pos = ash_arith(loc);
+                if (colon) *colon = ':';
 
+                /* Read LEN in ${var:POS:LEN} */
+                len = str - startp - 1;
                 /* *loc != '\0', guaranteed by parser */
                 if (quotes) {
                         char *ptr;
@@ -6662,26 +6670,21 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
                         }
                 }
                 orig_len = len;
-
                 if (*loc++ == ':') {
                         /* ${var::LEN} */
-                        len = number(loc);
+                        len = ash_arith(loc);
                 } else {
                         /* Skip POS in ${var:POS:LEN} */
                         len = orig_len;
                         while (*loc && *loc != ':') {
-                                /* TODO?
-                                 * bash complains on: var=qwe; echo ${var:1a:123}
-                                if (!isdigit(*loc))
-                                        ash_msg_and_raise_error(msg_illnum, str);
-                                 */
                                 loc++;
                         }
                         if (*loc++ == ':') {
-                                len = number(loc);
+                                len = ash_arith(loc);
                         }
-//TODO: number() chokes on "-n". In bash, LEN=-n means strlen()-n
                 }
+#  undef ash_arith
+
                 if (pos < 0) {
                         /* ${VAR:$((-n)):l} starts n chars from the end */
                         pos = orig_len + pos;
@@ -6689,12 +6692,16 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
                 if ((unsigned)pos >= orig_len) {
                         /* apart from obvious ${VAR:999999:l},
                          * covers ${VAR:$((-9999999)):l} - result is ""
-                         * (bash-compat)
+                         * (bash compat)
                          */
                         pos = 0;
                         len = 0;
                 }
-                if (len > (orig_len - pos))
+                if (len < 0) {
+                        /* ${VAR:N:-M} sets LEN to strlen()-M */
+                        len = (orig_len - pos) + len;
+                }
+                if ((unsigned)len > (orig_len - pos))
                         len = orig_len - pos;
 
                 for (str = startp; pos; str++, pos--) {
@@ -6710,6 +6717,7 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
                 amount = loc - expdest;
                 STADJUST(amount, expdest);
                 return loc;
+        }
 #endif /* BASH_SUBSTR */
         }
 
@@ -6754,6 +6762,7 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
 #if BASH_PATTERN_SUBST
         workloc = expdest - (char *)stackblock();
         if (subtype == VSREPLACE || subtype == VSREPLACEALL) {
+                int len;
                 char *idx, *end;
 
                 if (!repl) {
diff --git a/shell/ash_test/ash-vars/var_bash1b.right b/shell/ash_test/ash-vars/var_bash1b.right
new file mode 100644
index 000000000..fafc0f07c
--- /dev/null
+++ b/shell/ash_test/ash-vars/var_bash1b.right
@@ -0,0 +1,23 @@
+all    |0123456
+4:     |456
+4:2    |45
+4:-1   |45
+4:-2   |4
+4:-3   |
+-4:    |3456
+-4:2   |34
+-4:-1  |345
+-4:-2  |34
+-4:-3  |3
+-4:-4  |
+-4:i=2 |34
+-4:i=-2|34
+-4:i=-3|3
+-4:i=-4|
+-5:    |23456
+-6:    |123456
+-7:    |0123456
+-8:    |
+-9:    |
+-9:-99 |
+Ok:0
diff --git a/shell/ash_test/ash-vars/var_bash1b.tests b/shell/ash_test/ash-vars/var_bash1b.tests
new file mode 100755
index 000000000..efbdef35c
--- /dev/null
+++ b/shell/ash_test/ash-vars/var_bash1b.tests
@@ -0,0 +1,24 @@
+set -- 0123456
+        echo "all    |"$1
+        echo "4:     |"${1:4}
+        echo "4:2    |"${1:4:2}
+        echo "4:-1   |"${1:4:-1}
+        echo "4:-2   |"${1:4:-2}
+        echo "4:-3   |"${1:4:-3}
+        echo "-4:    |"${1: -4}
+        echo "-4:2   |"${1: -4:2}
+        echo "-4:-1  |"${1: -4:-1}
+        echo "-4:-2  |"${1: -4:-2}
+        echo "-4:-3  |"${1: -4:-3}
+        echo "-4:-4  |"${1: -4:-4}
+i=2;    echo "-4:i=2 |"${1: -4:i}
+i=-2;   echo "-4:i=-2|"${1: -4:i}
+i=-3;   echo "-4:i=-3|"${1: -4:i}
+i=-4;   echo "-4:i=-4|"${1: -4:i}
+        echo "-5:    |"${1: -5}
+        echo "-6:    |"${1: -6}
+        echo "-7:    |"${1: -7}
+        echo "-8:    |"${1: -8}
+        echo "-9:    |"${1: -9}
+        echo "-9:-99 |"${1: -9:-99}
+echo Ok:$?