1 /* Auxiliary functions for the creation of subprocesses. Native Windows API.
2 Copyright (C) 2001, 2003-2017 Free Software Foundation, Inc.
3 Written by Bruno Haible <bruno@clisp.org>, 2003.
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
19 /* Get declarations of the native Windows API functions. */
20 # define WIN32_LEAN_AND_MEAN
24 /* Get _open_osfhandle(). */
32 /* Get _get_osfhandle(). */
33 # if GNULIB_MSVC_NOTHROW
34 # include "msvc-nothrow.h"
42 /* Duplicates a file handle, making the copy uninheritable.
43 Returns -1 for a file handle that is equivalent to closed. */
45 dup_noinherit (int fd
)
47 fd
= dup_cloexec (fd
);
48 if (fd
< 0 && errno
== EMFILE
)
49 error (EXIT_FAILURE
, errno
, _("_open_osfhandle failed"));
54 /* Returns a file descriptor equivalent to FD, except that the resulting file
55 descriptor is none of STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO.
56 FD must be open and non-inheritable. The result will be non-inheritable as
58 If FD < 0, FD itself is returned. */
60 fd_safer_noinherit (int fd
)
62 if (STDIN_FILENO
<= fd
&& fd
<= STDERR_FILENO
)
64 /* The recursion depth is at most 3. */
65 int nfd
= fd_safer_noinherit (dup_noinherit (fd
));
66 int saved_errno
= errno
;
74 /* Duplicates a file handle, making the copy uninheritable and ensuring the
75 result is none of STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO.
76 Returns -1 for a file handle that is equivalent to closed. */
78 dup_safer_noinherit (int fd
)
80 return fd_safer_noinherit (dup_noinherit (fd
));
83 /* Undoes the effect of TEMPFD = dup_safer_noinherit (ORIGFD); */
85 undup_safer_noinherit (int tempfd
, int origfd
)
89 if (dup2 (tempfd
, origfd
) < 0)
90 error (EXIT_FAILURE
, errno
, _("cannot restore fd %d: dup2 failed"),
96 /* origfd was closed or open to no handle at all. Set it to a closed
97 state. This is (nearly) equivalent to the original state. */
102 /* Prepares an argument vector before calling spawn().
103 Note that spawn() does not by itself call the command interpreter
104 (getenv ("COMSPEC") != NULL ? getenv ("COMSPEC") :
105 ({ OSVERSIONINFO v; v.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
107 v.dwPlatformId == VER_PLATFORM_WIN32_NT;
108 }) ? "cmd.exe" : "command.com").
109 Instead it simply concatenates the arguments, separated by ' ', and calls
110 CreateProcess(). We must quote the arguments since Windows CreateProcess()
111 interprets characters like ' ', '\t', '\\', '"' (but not '<' and '>') in a
113 - Space and tab are interpreted as delimiters. They are not treated as
114 delimiters if they are surrounded by double quotes: "...".
115 - Unescaped double quotes are removed from the input. Their only effect is
116 that within double quotes, space and tab are treated like normal
118 - Backslashes not followed by double quotes are not special.
119 - But 2*n+1 backslashes followed by a double quote become
120 n backslashes followed by a double quote (n >= 0):
124 - '*', '?' characters may get expanded through wildcard expansion in the
125 callee: By default, in the callee, the initialization code before main()
126 takes the result of GetCommandLine(), wildcard-expands it, and passes it
127 to main(). The exceptions to this rule are:
128 - programs that inspect GetCommandLine() and ignore argv,
129 - mingw programs that have a global variable 'int _CRT_glob = 0;',
130 - Cygwin programs, when invoked from a Cygwin program.
133 # 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*?"
134 # 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"
136 # define SHELL_SPECIAL_CHARS ""
137 # define SHELL_SPACE_CHARS ""
140 prepare_spawn (char **argv
)
146 /* Count number of arguments. */
147 for (argc
= 0; argv
[argc
] != NULL
; argc
++)
150 /* Allocate new argument vector. */
151 new_argv
= XNMALLOC (1 + argc
+ 1, char *);
153 /* Add an element upfront that can be used when argv[0] turns out to be a
154 script, not a program.
155 On Unix, this would be "/bin/sh". On native Windows, "sh" is actually
156 "sh.exe". We have to omit the directory part and rely on the search in
157 PATH, because the mingw "mount points" are not visible inside Windows
159 *new_argv
++ = "sh.exe";
161 /* Put quoted arguments into the new argument vector. */
162 for (i
= 0; i
< argc
; i
++)
164 const char *string
= argv
[i
];
166 if (string
[0] == '\0')
167 new_argv
[i
] = xstrdup ("\"\"");
168 else if (strpbrk (string
, SHELL_SPECIAL_CHARS
) != NULL
)
170 bool quote_around
= (strpbrk (string
, SHELL_SPACE_CHARS
) != NULL
);
172 unsigned int backslashes
;
181 for (s
= string
; *s
!= '\0'; s
++)
185 length
+= backslashes
+ 1;
193 length
+= backslashes
+ 1;
195 quoted_string
= (char *) xmalloc (length
+ 1);
201 for (s
= string
; *s
!= '\0'; s
++)
207 for (j
= backslashes
+ 1; j
> 0; j
--)
219 for (j
= backslashes
; j
> 0; j
--)
225 new_argv
[i
] = quoted_string
;
228 new_argv
[i
] = (char *) string
;
230 new_argv
[argc
] = NULL
;