From 77dfd7b78389c718dca29d43e446dc888b2dbaff Mon Sep 17 00:00:00 2001
From: ridiculousfish <corydoras@ridiculousfish.com>
Date: Thu, 28 Mar 2013 17:45:49 -0700
Subject: [PATCH] Fix printf's Unicode support
 https://github.com/fish-shell/fish-shell/issues/625

---
 builtin_printf.cpp | 48 ++++++++++++++++++++++++++++------------------
 1 file changed, 29 insertions(+), 19 deletions(-)

diff --git a/builtin_printf.cpp b/builtin_printf.cpp
index bdd1de097..eb7700dd9 100644
--- a/builtin_printf.cpp
+++ b/builtin_printf.cpp
@@ -342,29 +342,39 @@ long builtin_printf_state_t::print_esc(const wchar_t *escstart, bool octal_0)
     else if (*p == L'u' || *p == L'U')
     {
         wchar_t esc_char = *p;
-        unsigned int uni_value;
-
-        uni_value = 0;
-        for (esc_length = (esc_char == L'u' ? 4 : 8), ++p;
-                esc_length > 0;
-                --esc_length, ++p)
+        p++;
+        uint32_t uni_value = 0;
+        for (size_t esc_length = 0; esc_length < (esc_char == L'u' ? 4 : 8); esc_length++)
         {
             if (! is_hex_digit(*p))
-                this->fatal_error(_(L"missing hexadecimal number in escape"));
+            {
+                /* Escape sequence must be done. Complain if we didn't get anything */
+                if (esc_length == 0)
+                {
+                    this->fatal_error(_(L"Missing hexadecimal number in Unicode escape"));
+                }
+                break;
+            }
             uni_value = uni_value * 16 + hex_to_bin(*p);
+            p++;
         }
-
-        /* A universal character name shall not specify a character short
-        identifier in the range 00000000 through 00000020, 0000007F through
-        0000009F, or 0000D800 through 0000DFFF inclusive. A universal
-        character name shall not designate a character in the required
-        character set.  */
-        if ((uni_value <= 0x9f
-                && uni_value != 0x24 && uni_value != 0x40 && uni_value != 0x60)
-                || (uni_value >= 0xd800 && uni_value <= 0xdfff))
-            this->fatal_error(_(L"invalid universal character name \\%c%0*x"),
-                          esc_char, (esc_char == L'u' ? 4 : 8), uni_value);
-        this->append_format_output(L"%lc", uni_value);
+        
+        /* PCA GNU printf respects the limitations described in ISO N717, about which universal characters "shall not" be specified. I believe this limitation is for the benefit of compilers; I see no reason to impose it in builtin_printf.
+        
+          If __STDC_ISO_10646__ is defined, then it means wchar_t can and does hold Unicode code points, so just use that. If not defined, use the %lc printf conversion; this probably won't do anything good if your wide character set is not Unicode, but such platforms are exceedingly rare.
+        */
+        if (uni_value > 0x10FFFF)
+        {
+            this->fatal_error(_(L"Unicode character out of range: \\%c%0*x"), esc_char, (esc_char == L'u' ? 4 : 8), uni_value);
+        }
+        else
+        {
+#if defined(__STDC_ISO_10646__)
+            this->append_output(uni_value);
+#else
+            this->append_format_output(L"%lc", uni_value);
+        }
+#endif
     }
     else
     {