Improve execve() path argument munging

Munging of paths passed inside the system() interpreter command is no
longer supported. You have to pass your paths to posix_spawn() or the
execve() family of functions if you want them to be munged. The first
three characters must match `^/[a-z]/` in which case, it'll be turned
into a DOS-style drive path with backslashes.

libc/calls/mkntcmdline.c

@@ -16,11 +16,17 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/calls/syscall_support-nt.internal.h"
+#include "libc/dce.h"
+#include "libc/errno.h"
+#include "libc/limits.h"
 #include "libc/mem/mem.h"
+#include "libc/nt/files.h"
 #include "libc/proc/ntspawn.h"
 #include "libc/str/str.h"
 #include "libc/str/thompike.h"
 #include "libc/str/utf16.h"
+#include "libc/sysv/consts/at.h"
 #include "libc/sysv/errfuns.h"
 
 #define APPEND(c)     \
@@ -54,6 +60,12 @@ static inline int IsAlpha(int c) {
   return ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z');
 }
 
+static bool LooksLikeCosmoDrivePath(const char *s) {
+  return s[0] == '/' &&    //
+         IsAlpha(s[1]) &&  //
+         s[2] == '/';
+}
+
 // Converts System V argv to Windows-style command line.
 //
 // Escaping is performed and it's designed to round-trip with
@@ -68,20 +80,31 @@ static inline int IsAlpha(int c) {
 // @see libc/runtime/getdosargv.c
 // @asyncsignalsafe
 textwindows int mkntcmdline(char16_t cmdline[32767], char *const argv[]) {
+  char *arg;
   int slashes, n;
   bool needsquote;
   size_t i, j, k, s;
+  char argbuf[PATH_MAX];
   for (k = i = 0; argv[i]; ++i) {
     if (i) APPEND(u' ');
-    if ((needsquote = NeedsQuotes(argv[i]))) APPEND(u'"');
+    if (LooksLikeCosmoDrivePath(argv[i]) &&
+        strlcpy(argbuf, argv[i], PATH_MAX) < PATH_MAX) {
+      mungentpath(argbuf);
+      arg = argbuf;
+    } else {
+      arg = argv[i];
+    }
+    if ((needsquote = NeedsQuotes(arg))) {
+      APPEND(u'"');
+    }
     for (slashes = j = 0;;) {
-      wint_t x = argv[i][j++] & 255;
+      wint_t x = arg[j++] & 255;
       if (x >= 0300) {
         n = ThomPikeLen(x);
         x = ThomPikeByte(x);
         while (--n) {
           wint_t y;
-          if ((y = argv[i][j++] & 255)) {
+          if ((y = arg[j++] & 255)) {
             x = ThomPikeMerge(x, y);
           } else {
             x = 0;
@@ -90,28 +113,6 @@ textwindows int mkntcmdline(char16_t cmdline[32767], char *const argv[]) {
         }
       }
       if (!x) break;
-      if (x == '/' || x == '\\') {
-        if (!i) {
-          // turn / into \ for first argv[i]
-          x = '\\';
-          // turn \c\... into c:\ for first argv[i]
-          if (k == 2 && IsAlpha(cmdline[1]) && cmdline[0] == '\\') {
-            cmdline[0] = cmdline[1];
-            cmdline[1] = ':';
-          }
-        } else {
-          // turn stuff like `less /c/...`
-          //            into `less c:/...`
-          // turn stuff like `more <"/c/..."`
-          //            into `more <"c:/..."`
-          if (k > 3 && IsAlpha(cmdline[k - 1]) &&
-              (cmdline[k - 2] == '/' || cmdline[k - 2] == '\\') &&
-              (cmdline[k - 3] == '"' || cmdline[k - 3] == ' ')) {
-            cmdline[k - 2] = cmdline[k - 1];
-            cmdline[k - 1] = ':';
-          }
-        }
-      }
       if (x == '\\') {
         ++slashes;
       } else if (x == '"') {

libc/calls/mkntenvblock.c

@@ -19,6 +19,7 @@
 #include "libc/assert.h"
 #include "libc/intrin/getenv.internal.h"
 #include "libc/mem/alloca.h"
+#include "libc/proc/ntspawn.h"
 #include "libc/runtime/runtime.h"
 #include "libc/runtime/stack.h"
 #include "libc/str/str.h"
@@ -51,38 +52,6 @@ static textwindows int Compare(const char *l, const char *r) {
   return a - b;
 }
 
-static textwindows void FixPath(char *path) {
-  char *p;
-
-  // turn colon into semicolon
-  // unless it already looks like a dos path
-  for (p = path; *p; ++p) {
-    if (p[0] == ':' && p[1] != '\\') {
-      p[0] = ';';
-    }
-  }
-
-  // turn /c/... into c:\...
-  p = path;
-  if (p[0] == '/' && IsAlpha(p[1]) && p[2] == '/') {
-    p[0] = p[1];
-    p[1] = ':';
-  }
-  for (; *p; ++p) {
-    if (p[0] == ';' && p[1] == '/' && IsAlpha(p[2]) && p[3] == '/') {
-      p[1] = p[2];
-      p[2] = ':';
-    }
-  }
-
-  // turn slash into backslash
-  for (p = path; *p; ++p) {
-    if (*p == '/') {
-      *p = '\\';
-    }
-  }
-}
-
 static textwindows int InsertString(struct EnvBuilder *env, const char *str) {
   int c, i, cmp;
   char *var, *path = 0;
@@ -101,7 +70,7 @@ static textwindows int InsertString(struct EnvBuilder *env, const char *str) {
   } while (c);
 
   // fixup key=/c/... → key=c:\...
-  if (path) FixPath(path);
+  if (path) mungentpath(path);
 
   // append key=val to sorted list using insertion sort technique
   for (i = env->vari;; --i) {

libc/calls/mungentpath.c

@@ -0,0 +1,55 @@
+/*-*- 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 2023 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/proc/ntspawn.h"
+
+static inline int IsAlpha(int c) {
+  return ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z');
+}
+
+textwindows void mungentpath(char *path) {
+  char *p;
+
+  // turn colon into semicolon
+  // unless it already looks like a dos path
+  for (p = path; *p; ++p) {
+    if (p[0] == ':' && p[1] != '\\') {
+      p[0] = ';';
+    }
+  }
+
+  // turn /c/... into c:\...
+  p = path;
+  if (p[0] == '/' && IsAlpha(p[1]) && p[2] == '/') {
+    p[0] = p[1];
+    p[1] = ':';
+  }
+  for (; *p; ++p) {
+    if (p[0] == ';' && p[1] == '/' && IsAlpha(p[2]) && p[3] == '/') {
+      p[1] = p[2];
+      p[2] = ':';
+    }
+  }
+
+  // turn slash into backslash
+  for (p = path; *p; ++p) {
+    if (*p == '/') {
+      *p = '\\';
+    }
+  }
+}

libc/proc/ntspawn.h

@@ -5,6 +5,7 @@
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
+void mungentpath(char *);
 int mkntcmdline(char16_t[32767], char *const[]);
 int mkntenvblock(char16_t[32767], char *const[], char *const[], char[32767]);
 int ntspawn(int64_t, const char *, char *const[], char *const[], char *const[],

test/libc/calls/mkntcmdline_test.c

@@ -74,30 +74,14 @@ TEST(mkntcmdline, testUnicode) {
                cmdline);
 }
 
-TEST(mkntcmdline, fixAsBestAsWeCanForNow1) {
+TEST(mkntcmdline, fixit) {
   char *argv1[] = {
-      "/C/WINDOWS/system32/cmd.exe",
+      "/C/Program Files/doom/doom.exe",
-      "/C",
+      "--version",
-      "more <\"/C/Users/jart/AppData/Local/Temp/tmplquaa_d6\"",
       NULL,
   };
   EXPECT_NE(-1, mkntcmdline(cmdline, argv1));
-  EXPECT_STREQ(u"C:\\WINDOWS\\system32\\cmd.exe /C \"more <"
+  EXPECT_STREQ(u"\"C:\\Program Files\\doom\\doom.exe\" --version", cmdline);
-               u"\"\"\"C:/Users/jart/AppData/Local/Temp/tmplquaa_d6\"\"\"\"",
-               cmdline);
-}
-
-TEST(mkntcmdline, fixAsBestAsWeCanForNow2) {
-  char *argv1[] = {
-      "/C/WINDOWS/system32/cmd.exe",
-      "/C",
-      "less /C/Users/jart/AppData/Local/Temp/tmplquaa_d6",
-      NULL,
-  };
-  EXPECT_NE(-1, mkntcmdline(cmdline, argv1));
-  EXPECT_STREQ(u"C:\\WINDOWS\\system32\\cmd.exe /C \"less "
-               u"C:/Users/jart/AppData/Local/Temp/tmplquaa_d6\"",
-               cmdline);
 }
 
 TEST(mkntcmdline, testWut) {