shell: implement optional "BASE#nnnn" numeric literals

function                                             old     new   delta
evaluate_string                                      729     851    +122

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

3 files changed, 51 insertions, 6 deletions

diff --git a/shell/Config.src b/shell/Config.src
index bc7218fe5..d7623f774 100644
--- a/shell/Config.src
+++ b/shell/Config.src
@@ -99,6 +99,11 @@ config FEATURE_SH_MATH_64
         slightly larger, but will allow computation with very large numbers.
         This is not in POSIX, so do not rely on this in portable code.
 
+config FEATURE_SH_MATH_BASE
+        bool "Support BASE#nnnn literals"
+        default y
+        depends on FEATURE_SH_MATH
+
 config FEATURE_SH_EXTRA_QUIET
         bool "Hide message on interactive shell startup"
         default y
diff --git a/shell/math.c b/shell/math.c
index 611b3beab..2ea0317e9 100644
--- a/shell/math.c
+++ b/shell/math.c
@@ -513,6 +513,42 @@ static const char op_tokens[] ALIGN1 = {
 };
 #define ptr_to_rparen (&op_tokens[sizeof(op_tokens)-7])
 
+#if ENABLE_FEATURE_SH_MATH_BASE
+static arith_t strto_arith_t(const char *nptr, char **endptr)
+{
+        unsigned base;
+        arith_t n;
+
+# if ENABLE_FEATURE_SH_MATH_64
+        n = strtoull(nptr, endptr, 0);
+# else
+        n = strtoul(nptr, endptr, 0);
+# endif
+        if (**endptr != '#'
+         || (*nptr < '1' || *nptr > '9')
+         || (n < 2 || n > 64)
+        ) {
+                return n;
+        }
+
+        /* It's "N#nnnn" or "NN#nnnn" syntax, NN can't start with 0,
+         * NN is in 2..64 range.
+         */
+        base = (unsigned)n;
+        n = 0;
+        nptr = *endptr + 1;
+        /* bash allows "N#" (empty "nnnn" part) */
+        while (isdigit(*nptr)) {
+                /* bash does not check for overflows */
+                n = n * base + (*nptr++ - '0');
+        }
+        *endptr = (char*)nptr;
+        return n;
+}
+#define strto_arith_t(nptr, endptr, base_is_always_0) \
+        strto_arith_t(nptr, endptr)
+#endif
+
 static arith_t FAST_FUNC
 evaluate_string(arith_state_t *math_state, const char *expr)
 {
diff --git a/shell/math.h b/shell/math.h
index 2c5ae9b44..ec9decb1f 100644
--- a/shell/math.h
+++ b/shell/math.h
@@ -65,15 +65,19 @@ PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
 
 #if ENABLE_FEATURE_SH_MATH_64
 typedef long long arith_t;
-#define ARITH_FMT "%lld"
-#define strto_arith_t strtoull
+# define ARITH_FMT "%lld"
 #else
 typedef long arith_t;
-#define ARITH_FMT "%ld"
-#define strto_arith_t strtoul
+# define ARITH_FMT "%ld"
+#endif
+
+#if !ENABLE_FEATURE_SH_MATH_BASE
+# if ENABLE_FEATURE_SH_MATH_64
+#  define strto_arith_t strtoull
+# else
+#  define strto_arith_t strtoul
+# endif
 #endif
-//TODO: bash supports "BASE#nnnnn" numeric literals, e.g. 2#1111 = 15.
-//Make strto_arith_t() support that?
 
 typedef const char* FAST_FUNC (*arith_var_lookup_t)(const char *name);
 typedef void        FAST_FUNC (*arith_var_set_t)(const char *name, const char *val);