Initial import

libc/runtime/getdosargv.c

@@ -0,0 +1,115 @@
+/*-*- 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/bits/bits.h"
+#include "libc/bits/pushpop.h"
+#include "libc/bits/safemacros.h"
+#include "libc/runtime/internal.h"
+#include "libc/str/appendchar.h"
+#include "libc/str/str.h"
+
+/* TODO(jart): Make early-stage data structures happen. */
+#undef isspace
+#undef iswspace
+#define isspace(c) ((c) == ' ' || (c) == '\t' || (c) == '\n' || (c) == '\r')
+#define iswspace(c) isspace(c)
+
+struct DosArgv {
+  const char16_t *s;
+  char *p;
+  char *pe;
+  wint_t wc;
+};
+
+static textwindows void decodedosargv(struct DosArgv *st) {
+  st->s += getutf16(st->s, &st->wc);
+}
+
+static textwindows void appenddosargv(struct DosArgv *st, wint_t wc) {
+  if (st->p < st->pe) {
+    st->p += tpencode(st->p, st->pe - st->p, wc, false);
+  }
+}
+
+/**
+ * Tokenizes and transcodes Windows NT CLI args, thus avoiding
+ * CommandLineToArgv() schlepping in forty megs of dependencies.
+ *
+ * @param s is the command line string provided by the executive
+ * @param buf is where we'll store double-NUL-terminated decoded args
+ * @param size is how many bytes are available in buf
+ * @param argv is where we'll store the decoded arg pointer array, which
+ *     is guaranteed to be NULL-terminated if max>0
+ * @param max specifies the item capacity of argv, or 0 to do scanning
+ * @return number of args written, excluding the NULL-terminator; or,
+ *     if the output buffer wasn't passed, or was too short, then the
+ *     number of args that *would* have been written is returned; and
+ *     there are currently no failure conditions that would have this
+ *     return -1 since it doesn't do system calls
+ * @see test/libc/dosarg_test.c
+ * @see libc/runtime/ntspawn.c
+ * @note kudos to Simon Tatham for figuring out quoting behavior
+ */
+textwindows int getdosargv(const char16_t *cmdline, char *buf, size_t size,
+                           char **argv, size_t max) {
+  bool inquote;
+  size_t i, argc, slashes, quotes;
+  struct DosArgv st;
+  st.s = cmdline;
+  st.p = buf;
+  st.pe = buf + size;
+  argc = 0;
+  decodedosargv(&st);
+  while (st.wc) {
+    while (st.wc && iswspace(st.wc)) decodedosargv(&st);
+    if (!st.wc) break;
+    if (++argc < max) {
+      argv[argc - 1] = st.p < st.pe ? st.p : NULL;
+    }
+    inquote = false;
+    while (st.wc) {
+      if (!inquote && isspace(st.wc)) break;
+      if (st.wc == '"' || st.wc == '\\') {
+        slashes = 0;
+        quotes = 0;
+        while (st.wc == '\\') decodedosargv(&st), slashes++;
+        while (st.wc == '"') decodedosargv(&st), quotes++;
+        if (!quotes) {
+          while (slashes--) appenddosargv(&st, '\\');
+        } else {
+          while (slashes >= 2) appenddosargv(&st, '\\'), slashes -= 2;
+          if (slashes) appenddosargv(&st, '"'), quotes--;
+          if (quotes > 0) {
+            if (!inquote) quotes--;
+            for (i = 3; i <= quotes + 1; i += 3) appenddosargv(&st, '"');
+            inquote = (quotes % 3 == 0);
+          }
+        }
+      } else {
+        appenddosargv(&st, st.wc);
+        decodedosargv(&st);
+      }
+    }
+    appenddosargv(&st, '\0');
+  }
+  appenddosargv(&st, '\0');
+  if (size) buf[min(st.p - buf, size - 1)] = '\0';
+  if (max) argv[min(argc, max - 1)] = NULL;
+  return argc;
+}