shell/read: check that variable names are sane

function                                             old     new   delta
shell_builtin_read                                  1000    1055     +55
parse_command                                       1460    1463      +3
builtin_umask                                        121     123      +2
is_well_formed_var_name                               73      66      -7

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

1 files changed, 13 insertions, 4 deletions

diff --git a/shell/shell_common.c b/shell/shell_common.c
index 99bb91c6f..669a18dfd 100644
--- a/shell/shell_common.c
+++ b/shell/shell_common.c
@@ -19,8 +19,17 @@
 #include "libbb.h"
 #include "shell_common.h"
 
-#if IFS_BROKEN
 const char defifsvar[] ALIGN1 = "IFS= \t\n";
-#else
-const char defifs[] ALIGN1 = " \t\n";
-#endif
+
+
+int FAST_FUNC is_well_formed_var_name(const char *s, char terminator)
+{
+	if (!s || !(isalpha(*s) || *s == '_'))
+		return 0;
+
+	do
+		s++;
+	while (isalnum(*s) || *s == '_');
+
+	return *s == terminator;
+}