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Diffstat (limited to 'lib/w32spawn.h')
| -rw-r--r-- | lib/w32spawn.h | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/lib/w32spawn.h b/lib/w32spawn.h new file mode 100644 index 0000000..58b0392 --- /dev/null +++ b/lib/w32spawn.h @@ -0,0 +1,212 @@ +/* Auxiliary functions for the creation of subprocesses. Native Woe32 API. + Copyright (C) 2001, 2003-2011 Free Software Foundation, Inc. + Written by Bruno Haible <bruno@clisp.org>, 2003. + + 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; either version 3 of the License, or + (at your option) any later version. + + 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, see <http://www.gnu.org/licenses/>. */ + +/* Get declarations of the Win32 API functions. */ +#define WIN32_LEAN_AND_MEAN +#include <windows.h> + +/* Get _get_osfhandle() and _open_osfhandle(). */ +#include <io.h> + +#include <stdbool.h> +#include <string.h> +#include <unistd.h> +#include <errno.h> + +#include "cloexec.h" +#include "xalloc.h" + +/* Duplicates a file handle, making the copy uninheritable. + Returns -1 for a file handle that is equivalent to closed. */ +static int +dup_noinherit (int fd) +{ + fd = dup_cloexec (fd); + if (fd < 0 && errno == EMFILE) + error (EXIT_FAILURE, errno, _("_open_osfhandle failed")); + + return fd; +} + +/* Returns a file descriptor equivalent to FD, except that the resulting file + descriptor is none of STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO. + FD must be open and non-inheritable. The result will be non-inheritable as + well. + If FD < 0, FD itself is returned. */ +static int +fd_safer_noinherit (int fd) +{ + if (STDIN_FILENO <= fd && fd <= STDERR_FILENO) + { + /* The recursion depth is at most 3. */ + int nfd = fd_safer_noinherit (dup_noinherit (fd)); + int saved_errno = errno; + close (fd); + errno = saved_errno; + return nfd; + } + return fd; +} + +/* Duplicates a file handle, making the copy uninheritable and ensuring the + result is none of STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO. + Returns -1 for a file handle that is equivalent to closed. */ +static int +dup_safer_noinherit (int fd) +{ + return fd_safer_noinherit (dup_noinherit (fd)); +} + +/* Undoes the effect of TEMPFD = dup_safer_noinherit (ORIGFD); */ +static void +undup_safer_noinherit (int tempfd, int origfd) +{ + if (tempfd >= 0) + { + if (dup2 (tempfd, origfd) < 0) + error (EXIT_FAILURE, errno, _("cannot restore fd %d: dup2 failed"), + origfd); + close (tempfd); + } + else + { + /* origfd was closed or open to no handle at all. Set it to a closed + state. This is (nearly) equivalent to the original state. */ + close (origfd); + } +} + +/* Prepares an argument vector before calling spawn(). + Note that spawn() does not by itself call the command interpreter + (getenv ("COMSPEC") != NULL ? getenv ("COMSPEC") : + ({ OSVERSIONINFO v; v.dwOSVersionInfoSize = sizeof(OSVERSIONINFO); + GetVersionEx(&v); + v.dwPlatformId == VER_PLATFORM_WIN32_NT; + }) ? "cmd.exe" : "command.com"). + Instead it simply concatenates the arguments, separated by ' ', and calls + CreateProcess(). We must quote the arguments since Win32 CreateProcess() + interprets characters like ' ', '\t', '\\', '"' (but not '<' and '>') in a + special way: + - Space and tab are interpreted as delimiters. They are not treated as + delimiters if they are surrounded by double quotes: "...". + - Unescaped double quotes are removed from the input. Their only effect is + that within double quotes, space and tab are treated like normal + characters. + - Backslashes not followed by double quotes are not special. + - But 2*n+1 backslashes followed by a double quote become + n backslashes followed by a double quote (n >= 0): + \" -> " + \\\" -> \" + \\\\\" -> \\" + */ +#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" +#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" +static char ** +prepare_spawn (char **argv) +{ + size_t argc; + char **new_argv; + size_t i; + + /* Count number of arguments. */ + for (argc = 0; argv[argc] != NULL; argc++) + ; + + /* Allocate new argument vector. */ + new_argv = XNMALLOC (1 + argc + 1, char *); + + /* Add an element upfront that can be used when argv[0] turns out to be a + script, not a program. + On Unix, this would be "/bin/sh". On native Windows, "sh" is actually + "sh.exe". We have to omit the directory part and rely on the search in + PATH, because the mingw "mount points" are not visible inside Win32 + CreateProcess(). */ + *new_argv++ = "sh.exe"; + + /* Put quoted arguments into the new argument vector. */ + for (i = 0; i < argc; i++) + { + const char *string = argv[i]; + + if (string[0] == '\0') + new_argv[i] = xstrdup ("\"\""); + else if (strpbrk (string, SHELL_SPECIAL_CHARS) != NULL) + { + bool quote_around = (strpbrk (string, SHELL_SPACE_CHARS) != NULL); + size_t length; + unsigned int backslashes; + const char *s; + char *quoted_string; + char *p; + + length = 0; + backslashes = 0; + if (quote_around) + length++; + for (s = string; *s != '\0'; s++) + { + char c = *s; + if (c == '"') + length += backslashes + 1; + length++; + if (c == '\\') + backslashes++; + else + backslashes = 0; + } + if (quote_around) + length += backslashes + 1; + + quoted_string = (char *) xmalloc (length + 1); + + p = quoted_string; + backslashes = 0; + if (quote_around) + *p++ = '"'; + for (s = string; *s != '\0'; s++) + { + char c = *s; + if (c == '"') + { + unsigned int j; + for (j = backslashes + 1; j > 0; j--) + *p++ = '\\'; + } + *p++ = c; + if (c == '\\') + backslashes++; + else + backslashes = 0; + } + if (quote_around) + { + unsigned int j; + for (j = backslashes; j > 0; j--) + *p++ = '\\'; + *p++ = '"'; + } + *p = '\0'; + + new_argv[i] = quoted_string; + } + else + new_argv[i] = (char *) string; + } + new_argv[argc] = NULL; + + return new_argv; +} |