Reduce memory requirements for execve()

libc/calls/execve-nt.c

@@ -47,11 +47,8 @@ textwindows int execve$nt(const char *program, char *const argv[],
       close(i);
     }
   }
-  for (i = 0; argv[i];) ++i;
-  i = (i + 1) * sizeof(char *);
-  argv = memcpy(alloca(i), argv, i);
-  memcpy(argv, &program, sizeof(program));
-  rc = ntspawn(argv, envp, NULL, NULL, true, 0, NULL, &startinfo, &procinfo);
+  rc = ntspawn(program, argv, envp, NULL, NULL, true, 0, NULL, &startinfo,
+               &procinfo);
   if (rc == -1) return -1;
   CloseHandle(procinfo.hThread);
   do {

libc/calls/execve-sysv.c

@@ -25,15 +25,16 @@
 #include "libc/str/str.h"
 
 int execve$sysv(const char *prog, char *const argv[], char *const envp[]) {
-  size_t i, n;
-  char **shargs, bash[PATH_MAX];
+  size_t i;
+  char **shargs;
   if (__execve$sysv(prog, argv, envp) != -1) return 0;
   if (errno != ENOEXEC) return -1;
   for (i = 0; argv[i];) ++i;
   shargs = alloca((i + 2) * sizeof(char *));
   memcpy(shargs + 2, argv + 1, i * sizeof(char *));
   shargs[0] = !IsFreebsd() ? _PATH_BSHELL
-                           : firstnonnull(commandv("bash", bash), _PATH_BSHELL);
+                           : firstnonnull(commandv("bash", alloca(PATH_MAX)),
+                                          _PATH_BSHELL);
   shargs[1] = prog;
   return __execve$sysv(shargs[0], shargs, envp);
 }

libc/calls/hefty/fork-nt.c

@@ -137,8 +137,8 @@ textwindows int fork$nt(void) {
       startinfo.hStdInput = g_fds.p[0].handle;
       startinfo.hStdOutput = g_fds.p[1].handle;
       startinfo.hStdError = g_fds.p[2].handle;
-      if (ntspawn(g_argv, environ, &kNtIsInheritable, NULL, true, 0, NULL,
-                  &startinfo, &procinfo) != -1) {
+      if (ntspawn(g_argv[0], g_argv, environ, &kNtIsInheritable, NULL, true, 0,
+                  NULL, &startinfo, &procinfo) != -1) {
         CloseHandle(reader);
         CloseHandle(procinfo.hThread);
         if (weaken(__sighandrvas) &&

libc/calls/mkntcmdline.c

@@ -30,24 +30,28 @@
  * GetDosArgv() or GetDosArgv(). This function does NOT escape
  * command interpreter syntax, e.g. $VAR (sh), %VAR% (cmd).
  *
+ * @param cmdline is output buffer
+ * @param prog is used as argv[0]
  * @param argv is an a NULL-terminated array of UTF-8 strings
  * @return freshly allocated lpCommandLine or NULL w/ errno
  * @kudos Daniel Colascione for teaching how to quote
  * @see libc/runtime/dosargv.c
  */
-textwindows int mkntcmdline(char16_t cmdline[ARG_MAX], char *const argv[]) {
+textwindows int mkntcmdline(char16_t cmdline[ARG_MAX], const char *prog,
+                            char *const argv[]) {
+  char *arg;
   uint64_t w;
   wint_t x, y;
   int slashes, n;
   size_t i, j, k;
   bool needsquote;
   char16_t cbuf[2];
-  for (k = i = 0; argv[i]; ++i) {
+  for (arg = prog, k = i = 0; arg; arg = argv[++i]) {
     if (i) {
       cmdline[k++] = u' ';
       if (k == ARG_MAX) return e2big();
     }
-    needsquote = !*argv[i] || argv[i][strcspn(argv[i], " \t\n\v\"")];
+    needsquote = !arg[0] || arg[strcspn(arg, " \t\n\v\"")];
     if (needsquote) {
       cmdline[k++] = u'"';
       if (k == ARG_MAX) return e2big();
@@ -55,20 +59,20 @@ textwindows int mkntcmdline(char16_t cmdline[ARG_MAX], char *const argv[]) {
     for (j = 0;;) {
       if (needsquote) {
         slashes = 0;
-        while (argv[i][j] && argv[i][j] == '\\') slashes++, j++;
+        while (arg[j] && arg[j] == '\\') slashes++, j++;
         slashes <<= 1;
-        if (argv[i][j] == '"') slashes++;
+        if (arg[j] == '"') slashes++;
         while (slashes--) {
           cmdline[k++] = u'\\';
           if (k == ARG_MAX) return e2big();
         }
       }
-      x = argv[i][j++] & 0xff;
+      x = arg[j++] & 0xff;
       if (x >= 0300) {
         n = ThomPikeLen(x);
         x = ThomPikeByte(x);
         while (--n) {
-          if ((y = argv[i][j++] & 0xff)) {
+          if ((y = arg[j++] & 0xff)) {
             x = ThomPikeMerge(x, y);
           } else {
             x = 0;

libc/calls/ntspawn.c

@@ -58,7 +58,7 @@ struct SpawnBlock {
  * @see spawnve() which abstracts this function
  */
 textwindows int ntspawn(
-    char *const argv[], char *const envp[],
+    const char *prog, char *const argv[], char *const envp[],
     struct NtSecurityAttributes *opt_lpProcessAttributes,
     struct NtSecurityAttributes *opt_lpThreadAttributes, bool32 bInheritHandles,
     uint32_t dwCreationFlags, const char16_t *opt_lpCurrentDirectory,
@@ -80,7 +80,7 @@ textwindows int ntspawn(
       (block =
            MapViewOfFileExNuma(handle, kNtFileMapRead | kNtFileMapWrite, 0, 0,
                                blocksize, NULL, kNtNumaNoPreferredNode))) {
-    if (mkntcmdline(block->cmdline, argv) != -1 &&
+    if (mkntcmdline(block->cmdline, prog, argv) != -1 &&
         mkntenvblock(block->envvars, envp) != -1) {
       if (CreateProcess(NULL, block->cmdline, opt_lpProcessAttributes,
                         opt_lpThreadAttributes, bInheritHandles,

libc/calls/ntspawn.h

@@ -6,11 +6,12 @@
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
-int mkntcmdline(char16_t[ARG_MAX], char *const[]) hidden;
+int mkntcmdline(char16_t[ARG_MAX], const char *, char *const[]) hidden;
 int mkntenvblock(char16_t[ARG_MAX], char *const[]) hidden;
-int ntspawn(char *const[], char *const[], struct NtSecurityAttributes *,
-            struct NtSecurityAttributes *, bool32, uint32_t, const char16_t *,
-            const struct NtStartupInfo *, struct NtProcessInformation *) hidden;
+int ntspawn(const char *, char *const[], char *const[],
+            struct NtSecurityAttributes *, struct NtSecurityAttributes *,
+            bool32, uint32_t, const char16_t *, const struct NtStartupInfo *,
+            struct NtProcessInformation *) hidden;
 
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */