2 files changed, 20 insertions, 4 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 97dbe8687..fb7296f25 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1576,7 +1576,6 @@ extern const char bb_default_login_shell[];
 #undef islower
 #undef isprint
 #undef ispunct
-#undef isspace
 #undef isupper
 #undef isxdigit
 
@@ -1584,6 +1583,16 @@ extern const char bb_default_login_shell[];
 #undef isdigit
 #define isdigit(a) ((unsigned)((a) - '0') <= 9)
 
+/* This one is more efficient too! ~200 bytes */
+/* In POSIX/C locale (the only locale we care about: do we REALLY want
+ * to allow Unicode whitespace in, say, .conf files? nuts!)
+ * isspace is only these chars: "\t\n\v\f\r" and space.
+ * "\t\n\v\f\r" happen to have ASCII codes 9,10,11,12,13.
+ * Use that.
+ */
+#undef isspace
+#define isspace(a) ({ unsigned char bb__isspace = (a) - 9; bb__isspace == (' ' - 9) || bb__isspace <= (13 - 9); })
+
 #define ARRAY_SIZE(x) ((unsigned)(sizeof(x) / sizeof((x)[0])))
 
 
diff --git a/libbb/skip_whitespace.c b/libbb/skip_whitespace.c
index e85f3859f..7b123261b 100644
--- a/libbb/skip_whitespace.c
+++ b/libbb/skip_whitespace.c
@@ -11,15 +11,22 @@
 
 char* FAST_FUNC skip_whitespace(const char *s)
 {
-        /* NB: isspace('\0') returns 0 */
-        while (isspace(*s)) ++s;
+        /* In POSIX/C locale (the only locale we care about: do we REALLY want
+         * to allow Unicode whitespace in, say, .conf files? nuts!)
+         * isspace is only these chars: "\t\n\v\f\r" and space.
+         * "\t\n\v\f\r" happen to have ASCII codes 9,10,11,12,13.
+         * Use that.
+         */
+        while (*s == ' ' || (unsigned char)(*s - 9) <= (13 - 9))
+                s++;
 
         return (char *) s;
 }
 
 char* FAST_FUNC skip_non_whitespace(const char *s)
 {
-        while (*s && !isspace(*s)) ++s;
+        while (*s != '\0' && *s != ' ' && (unsigned char)(*s - 9) > (13 - 9))
+                s++;
 
         return (char *) s;
 }