From 1dc4b98ae13e505ea6abad8452ad7759d80e43cf Mon Sep 17 00:00:00 2001
From: Bruce Hill <bruce@bruce-hill.com>
Date: Wed, 9 Sep 2020 23:41:20 -0700
Subject: Improving escape handling

---
 utils.h | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

(limited to 'utils.h')

diff --git a/utils.h b/utils.h
index 80a884c..8012af1 100644
--- a/utils.h
+++ b/utils.h
@@ -55,3 +55,56 @@ static void visualize(const char *source, const char *ptr, const char *msg)
     if (visualize_delay > 0)
         usleep(visualize_delay);
 }
+
+/*
+ * Write an unescaped version of `src` to `dest` (at most bufsize-1 chars,
+ * terminated by a null byte)
+ */
+static size_t unescape_string(char *dest, const char *src, size_t bufsize)
+{
+    size_t len = 0;
+#define PUT(c) do { *(dest++) = (char)(c); ++len; } while (0)
+    for ( ; *src && len < bufsize; ++src) {
+        if (*src != '\\') {
+            PUT(*src);
+            continue;
+        }
+        ++src;
+        switch (*src) {
+            case 'a': PUT('\a'); break; case 'b': PUT('\b'); break;
+            case 'n': PUT('\n'); break; case 'r': PUT('\r'); break;
+            case 't': PUT('\t'); break; case 'v': PUT('\v'); break;
+            case 'e': PUT('\033'); break;
+            case 'x': { // Hex
+                static const char hextable[255] = {
+                    ['0']=0x10, ['1']=0x1, ['2']=0x2, ['3']=0x3, ['4']=0x4,
+                    ['5']=0x5, ['6']=0x6, ['7']=0x7, ['8']=0x8, ['9']=0x9,
+                    ['a']=0xa, ['b']=0xb, ['c']=0xc, ['d']=0xd, ['e']=0xe, ['f']=0xf,
+                    ['A']=0xa, ['B']=0xb, ['C']=0xc, ['D']=0xd, ['E']=0xe, ['F']=0xf,
+                };
+                if (hextable[(int)src[1]] && hextable[(int)src[2]]) {
+                    PUT((hextable[(int)src[1]] << 4) | (hextable[(int)src[2]] & 0xF));
+                    src += 2;
+                }
+                break;
+            }
+            case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': { // Octal
+                int c = *src - '0';
+                if ('0' <= src[1] && src[1] <= '7') {
+                    ++src;
+                    c = (c << 3) | (*src - '0');
+                    if ('0' <= src[1] && src[1] <= '7' && (c << 3) < 256) {
+                        ++src;
+                        c = (c << 3) | (*src - '0');
+                    }
+                }
+                PUT(c);
+                break;
+            }
+            default: PUT(*src); break;
+        }
+    }
+    *dest = '\0';
+    return len;
+#undef PUT
+}
-- 
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