iconv: Better mapping to RFC for UTF-7

- Direct use of characters instead of arcane arrays
- isxbase64 is not the Modified BASE64 alphabet, but the characters who
  needs to trigger an explicit shift back to US-ASCII. Make that clearer

Signed-off-by: Max Gautier <mg@max.gautier.name>
Reviewed-by: Adhemerval Zanellla  <adhemerval.zanella@linaro.org>

diff --git a/iconvdata/utf-7.c b/iconvdata/utf-7.c
index b5af9b217cf2ebb78f0c432d7fef3fba888341e9..815b1891c7600e4e29ebe315ef3d3c1df7ac4b3d 100644 (file)
--- a/iconvdata/utf-7.c
+++ b/iconvdata/utf-7.c
@@ -30,20 +30,27 @@
 
 
 
+static bool
+between (uint32_t const ch,
+        uint32_t const lower_bound, uint32_t const upper_bound)
+{
+  return (ch >= lower_bound && ch <= upper_bound);
+}
+
 /* The set of "direct characters":
    A-Z a-z 0-9 ' ( ) , - . / : ? space tab lf cr
 */
 
-static const unsigned char direct_tab[128 / 8] =
-  {
-    0x00, 0x26, 0x00, 0x00, 0x81, 0xf3, 0xff, 0x87,
-    0xfe, 0xff, 0xff, 0x07, 0xfe, 0xff, 0xff, 0x07
-  };
-
-static int
+static bool
 isdirect (uint32_t ch)
 {
-  return (ch < 128 && ((direct_tab[ch >> 3] >> (ch & 7)) & 1));
+  return (between (ch, 'A', 'Z')
+         || between (ch, 'a', 'z')
+         || between (ch, '0', '9')
+         || ch == '\'' || ch == '(' || ch == ')'
+         || between (ch, ',', '/')
+         || ch == ':' || ch == '?'
+         || ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r');
 }
 
 
@@ -52,33 +59,27 @@ isdirect (uint32_t ch)
    ! " # $ % & * ; < = > @ [ ] ^ _ ` { | }
 */
 
-static const unsigned char xdirect_tab[128 / 8] =
-  {
-    0x00, 0x26, 0x00, 0x00, 0xff, 0xf7, 0xff, 0xff,
-    0xff, 0xff, 0xff, 0xef, 0xff, 0xff, 0xff, 0x3f
-  };
-
-static int
+static bool
 isxdirect (uint32_t ch)
 {
-  return (ch < 128 && ((xdirect_tab[ch >> 3] >> (ch & 7)) & 1));
+  return (ch == '\t'
+         || ch == '\n'
+         || ch == '\r'
+         || (between (ch, ' ', '}') && ch != '+' && ch != '\\'));
 }
 
 
-/* The set of "extended base64 characters":
+/* Characters which needs to trigger an explicit shift back to US-ASCII (UTF-7
+   only): Modified base64 + '-' (shift back character)
    A-Z a-z 0-9 + / -
 */
 
-static const unsigned char xbase64_tab[128 / 8] =
-  {
-    0x00, 0x00, 0x00, 0x00, 0x00, 0xa8, 0xff, 0x03,
-    0xfe, 0xff, 0xff, 0x07, 0xfe, 0xff, 0xff, 0x07
-  };
-
-static int
-isxbase64 (uint32_t ch)
+static bool
+needs_explicit_shift (uint32_t ch)
 {
-  return (ch < 128 && ((xbase64_tab[ch >> 3] >> (ch & 7)) & 1));
+  return (between (ch, 'A', 'Z')
+         || between (ch, 'a', 'z')
+         || between (ch, '/', '9') || ch == '+' || ch == '-');
 }
 
 
@@ -252,7 +253,7 @@ base64 (unsigned int i)
                   indeed form a Low Surrogate.  */                           \
                uint32_t wc2 = wch & 0xffff;                                  \
                                                                              \
-               if (! __builtin_expect (wc2 >= 0xdc00 && wc2 < 0xe000, 1))    \
+               if (! __glibc_likely (wc2 >= 0xdc00 && wc2 < 0xe000))         \
                  {                                                           \
                    STANDARD_FROM_LOOP_ERR_HANDLER ((statep->__count = 0, 1));\
                  }                                                           \
@@ -372,7 +373,8 @@ base64 (unsigned int i)
            /* deactivate base64 encoding */                                  \
            size_t count;                                                     \
                                                                              \
-           count = ((statep->__count & 0x18) >= 0x10) + isxbase64 (ch) + 1;  \
+           count = ((statep->__count & 0x18) >= 0x10)                        \
+             + needs_explicit_shift (ch) + 1;                                \
            if (__glibc_unlikely (outptr + count > outend))                   \
              {                                                               \
                result = __GCONV_FULL_OUTPUT;                                 \
@@ -381,7 +383,7 @@ base64 (unsigned int i)
                                                                              \
            if ((statep->__count & 0x18) >= 0x10)                             \
              *outptr++ = base64 ((statep->__count >> 3) & ~3);               \
-           if (isxbase64 (ch))                                               \
+           if (needs_explicit_shift (ch))                                    \
              *outptr++ = '-';                                                \
            *outptr++ = (unsigned char) ch;                                   \
            statep->__count = 0;                                              \