1 files changed, 125 insertions, 0 deletions
diff --git a/src/slibc-human/escape.c b/src/slibc-human/escape.c
new file mode 100644
index 0000000..ea93108
--- /dev/null
+++ b/src/slibc-human/escape.c
@@ -0,0 +1,125 @@
+/**
+ * slibc — Yet another C library
+ * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <slib-human.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+
+
+/**
+ * Escapes a string.
+ * 
+ * @param   str    The unescaped string, may be `NULL`.
+ * @param   quote  The queue character, must be either ', "
+ *                 or a NUL-character (for no surrounding quotes).
+ *                 Note, these quotes are not added to output.
+ * @return         Escaped variant of the string, `NULL`.
+ *                 You are responsible for deallocating the
+ *                 returned pointer.
+ * 
+ * @throws  0       `str` is `NULL`.
+ * @throws  EINVAL  If `quote` is invalid.
+ * @throws  ENOMEM  The process cannot allocate more memory.
+ */
+char* escape(const char* str, char quote)
+{
+  char* r;
+  char* w;
+  char* rc;
+  size_t extra = 1, len, size;
+  unsigned char c;
+  
+  if (str == NULL)
+    return errno = 0, NULL;
+  
+  switch (quote)
+    {
+    case '\'':
+    case '\"':
+    case '\0':
+      break;
+    default:
+      return errno = EINVAL, NULL;
+    }
+  
+  for (r = str; *r; r++)
+    switch (*r)
+      {
+      case '\a':
+      case '\b':
+      case '\e':
+      case '\f':
+      case '\n':
+      case '\r':
+      case '\t':
+      case '\v':
+      case '\\':
+	extra += 1;
+	break;
+      case 0x7F:
+	extra += 3;
+	break;
+      default:
+	if (*r == quote)
+	  extra += 1;
+	else if (*r < ' ')
+	  extra += 3;
+	break;
+      }
+  
+  if (extra == 1)
+    return strdup(str);
+  
+  len = strlen(str);
+  if (__builtin_uaddl_overflow(len, extra, &size))
+    return errno = ENOMEM, NULL;
+  
+  w = rc = malloc(size * sizeof(char));
+  if (w == NULL)
+    return NULL;
+  
+  for (r = str; (c = *r); r++)
+    switch (c)
+      {
+      case '\a':  *w++ = '\\', *w++ = 'a';   break;
+      case '\b':  *w++ = '\\', *w++ = 'b';   break;
+      case 033:   *w++ = '\\', *w++ = 'e';   break;
+      case '\f':  *w++ = '\\', *w++ = 'f';   break;
+      case '\n':  *w++ = '\\', *w++ = 'n';   break;
+      case '\r':  *w++ = '\\', *w++ = 'r';   break;
+      case '\t':  *w++ = '\\', *w++ = 't';   break;
+      case '\v':  *w++ = '\\', *w++ = 'v';   break;
+      case '\\':  *w++ = '\\', *w++ = '\\';  break;
+      case 0x7F:  *w++ = '\\', *w++ = '1', *w++ = '7', *w++ = '7';  break;
+      default:
+	if (c == quote)
+	  *w++ = '\\', *w++ = quote;
+	else if (c < ' ')
+	  *w++ = '\\',
+	    *w++ = '0' + (c >> 6),
+	    *w++ = '0' + ((c >> 3) & 7),
+	    *w++ = '0' + (c & 7);
+	else
+	  *w++ = c;
+	break;
+      }
+  
+  return *w = 0, rc;
+}
+