ash: more general format ${var:EXPR:EXPR}

function                                             old     new   delta
subevalvar                                          1171    1202     +31
localcmd                                             364     366      +2

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 26 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) {