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/* Auxiliary functions for the creation of subprocesses. Native Woe32 API.
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Copyright (C) 2001, 2003-2011 Free Software Foundation, Inc.
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Written by Bruno Haible <bruno@clisp.org>, 2003.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* Get declarations of the Win32 API functions. */
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#define WIN32_LEAN_AND_MEAN
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/* Get _get_osfhandle() and _open_osfhandle(). */
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/* Duplicates a file handle, making the copy uninheritable.
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Returns -1 for a file handle that is equivalent to closed. */
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dup_noinherit (int fd)
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fd = dup_cloexec (fd);
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if (fd < 0 && errno == EMFILE)
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error (EXIT_FAILURE, errno, _("_open_osfhandle failed"));
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/* Returns a file descriptor equivalent to FD, except that the resulting file
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descriptor is none of STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO.
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FD must be open and non-inheritable. The result will be non-inheritable as
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If FD < 0, FD itself is returned. */
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fd_safer_noinherit (int fd)
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if (STDIN_FILENO <= fd && fd <= STDERR_FILENO)
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/* The recursion depth is at most 3. */
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int nfd = fd_safer_noinherit (dup_noinherit (fd));
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int saved_errno = errno;
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/* Duplicates a file handle, making the copy uninheritable and ensuring the
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result is none of STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO.
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Returns -1 for a file handle that is equivalent to closed. */
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dup_safer_noinherit (int fd)
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return fd_safer_noinherit (dup_noinherit (fd));
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/* Undoes the effect of TEMPFD = dup_safer_noinherit (ORIGFD); */
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undup_safer_noinherit (int tempfd, int origfd)
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if (dup2 (tempfd, origfd) < 0)
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error (EXIT_FAILURE, errno, _("cannot restore fd %d: dup2 failed"),
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/* origfd was closed or open to no handle at all. Set it to a closed
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state. This is (nearly) equivalent to the original state. */
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/* Prepares an argument vector before calling spawn().
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Note that spawn() does not by itself call the command interpreter
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(getenv ("COMSPEC") != NULL ? getenv ("COMSPEC") :
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({ OSVERSIONINFO v; v.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
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v.dwPlatformId == VER_PLATFORM_WIN32_NT;
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}) ? "cmd.exe" : "command.com").
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Instead it simply concatenates the arguments, separated by ' ', and calls
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CreateProcess(). We must quote the arguments since Win32 CreateProcess()
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interprets characters like ' ', '\t', '\\', '"' (but not '<' and '>') in a
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- Space and tab are interpreted as delimiters. They are not treated as
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delimiters if they are surrounded by double quotes: "...".
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- Unescaped double quotes are removed from the input. Their only effect is
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that within double quotes, space and tab are treated like normal
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- Backslashes not followed by double quotes are not special.
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- But 2*n+1 backslashes followed by a double quote become
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n backslashes followed by a double quote (n >= 0):
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#define SHELL_SPECIAL_CHARS "\"\\ \001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037"
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#define SHELL_SPACE_CHARS " \001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037"
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prepare_spawn (char **argv)
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/* Count number of arguments. */
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for (argc = 0; argv[argc] != NULL; argc++)
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/* Allocate new argument vector. */
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new_argv = XNMALLOC (1 + argc + 1, char *);
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/* Add an element upfront that can be used when argv[0] turns out to be a
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script, not a program.
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On Unix, this would be "/bin/sh". On native Windows, "sh" is actually
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"sh.exe". We have to omit the directory part and rely on the search in
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PATH, because the mingw "mount points" are not visible inside Win32
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*new_argv++ = "sh.exe";
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/* Put quoted arguments into the new argument vector. */
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for (i = 0; i < argc; i++)
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const char *string = argv[i];
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if (string[0] == '\0')
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new_argv[i] = xstrdup ("\"\"");
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else if (strpbrk (string, SHELL_SPECIAL_CHARS) != NULL)
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bool quote_around = (strpbrk (string, SHELL_SPACE_CHARS) != NULL);
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unsigned int backslashes;
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for (s = string; *s != '\0'; s++)
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length += backslashes + 1;
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length += backslashes + 1;
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quoted_string = (char *) xmalloc (length + 1);
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for (s = string; *s != '\0'; s++)
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for (j = backslashes + 1; j > 0; j--)
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for (j = backslashes; j > 0; j--)
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new_argv[i] = quoted_string;
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new_argv[i] = (char *) string;
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new_argv[argc] = NULL;
added
removed
lib/w32spawn.h
