libmagic: supply own ctype macros

Due to the current linker command line ordering, parts of lib(min)c
that are used exclusively by libmagic end up not being instrumented,
which then causes problems transferring pointers such as _ctype_tab_
and _tolower_tab_.  As a temporary workaround, we redefine the macros
that use those pointers.  A better long-term solution should
eventually render this patch obsolete.

Change-Id: Ice1d125ff6fb2f65ac6dcc6cf6eec7cd6176bee1

minix/llvm/static/magic/magic_eval_lib.c

@@ -12,6 +12,42 @@
 #include <math.h>
 #endif
 
+#ifdef __MINIX
+/* FIXME: due to the current linker command line ordering, parts of lib(min)c
+ * that are used exclusively by libmagic end up not being instrumented, which
+ * then causes problems transferring pointers such as _ctype_tab_ and
+ * _tolower_tab_. As a temporary workaround, we redefine the macros that use
+ * those pointers. This code is currently never triggered so it is not
+ * performance critical; obviously there are a million better ways to do this.
+ */
+#undef isalpha
+#define isalpha(c) ((unsigned)(((c) & ~0x20) - 'A') <= ('Z' - 'A'))
+#undef isupper
+#define isupper(c) ((unsigned)((c) - 'A') <= ('Z' - 'A'))
+#undef islower
+#define islower(c) ((unsigned)((c) - 'a') <= ('z' - 'a'))
+#undef isdigit
+#define isdigit(c) ((unsigned)((c) - '0') <= ('9' - '0'))
+static inline int __isxdigit(c) {
+    return isdigit(c) || (c >= 'A' && c <= 'F') || (c >= 'a' && c <= 'f');
+}
+#undef isxdigit
+#define isxdigit(c) (__isxdigit(c))
+static inline int __isspace(c) {
+    switch (c) {
+    case ' ': case '\t': case '\n': case '\v': case '\f': case '\r': return 1;
+    default: return 0;
+    }
+}
+#undef isspace
+#define isspace(c) (__isspace(c))
+static inline int __tolower(c) {
+    return isupper(c) ? (c | 0x20) : c;
+}
+#undef tolower
+#define tolower(c) (__tolower(c))
+#endif /* __MINIX */
+
 /* a token structure */
 struct tok {
     struct tok *next;