Add minor improvements and cleanup

libc/str/escapedos.c

@@ -0,0 +1,118 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ 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; version 2 of the License.                      │
+│                                                                              │
+│ 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, write to the Free Software                  │
+│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
+│ 02110-1301 USA                                                               │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/str/str.h"
+
+static textwindows bool shouldescapedos(const char16_t c) {
+  if (c == u'"') return true;
+  if (c == u'&') return true;
+  if (c == u'%') return true;
+  if (c == u'^') return true;
+  if (c == u'<') return true;
+  if (c == u'>') return true;
+  if (c == u'|') return true;
+  return false;
+}
+
+static textwindows bool shouldquotedos(const char16_t c) {
+  if (c == u' ') return true;
+  if (c == u'\t') return true;
+  if (c == u'\n') return true;
+  if (c == u'\v') return true;
+  if (c == u'"') return true;
+  if (c == u'*') return true;
+  return shouldescapedos(c);
+}
+
+/**
+ * Escapes command so DOS can run it.
+ * @see Iain Patterson's NSSM for original code in public domain
+ */
+textwindows bool escapedos(char16_t *buffer, unsigned buflen,
+                           const char16_t *unquoted, unsigned len) {
+  unsigned i, j, n;
+  if (len > buflen - 1) return false;
+  bool escape = false;
+  bool quotes = false;
+  for (i = 0; i < len; i++) {
+    if (shouldescapedos(unquoted[i])) {
+      escape = quotes = true;
+      break;
+    }
+    if (shouldquotedos(unquoted[i])) quotes = true;
+  }
+  if (!quotes) {
+    memmove(buffer, unquoted, (len + 1) * sizeof(char16_t));
+    return true;
+  }
+  /* "" */
+  unsigned quoted_len = 2;
+  if (escape) quoted_len += 2;
+  for (i = 0;; i++) {
+    n = 0;
+    while (i != len && unquoted[i] == u'\\') {
+      i++;
+      n++;
+    }
+    if (i == len) {
+      quoted_len += n * 2;
+      break;
+    } else if (unquoted[i] == u'"')
+      quoted_len += n * 2 + 2;
+    else
+      quoted_len += n + 1;
+    if (shouldescapedos(unquoted[i])) quoted_len += n;
+  }
+  if (quoted_len > buflen - 1) return false;
+  char16_t *s = buffer;
+  if (escape) *s++ = u'^';
+  *s++ = u'"';
+  for (i = 0;; i++) {
+    n = 0;
+    while (i != len && unquoted[i] == u'\\') {
+      i++;
+      n++;
+    }
+    if (i == len) {
+      for (j = 0; j < n * 2; j++) {
+        if (escape) *s++ = u'^';
+        *s++ = u'\\';
+      }
+      break;
+    } else if (unquoted[i] == u'"') {
+      for (j = 0; j < n * 2 + 1; j++) {
+        if (escape) *s++ = u'^';
+        *s++ = u'\\';
+      }
+      if (escape && shouldescapedos(unquoted[i])) *s++ = u'^';
+      *s++ = unquoted[i];
+    } else {
+      for (j = 0; j < n; j++) {
+        if (escape) *s++ = u'^';
+        *s++ = u'\\';
+      }
+      if (escape && shouldescapedos(unquoted[i])) *s++ = u'^';
+      *s++ = unquoted[i];
+    }
+  }
+  if (escape) *s++ = u'^';
+  *s++ = u'"';
+  *s++ = u'\0';
+  return true;
+}