/* Auxiliary functions for the creation of subprocesses. Native Woe32 API. Copyright (C) 2001, 2003-2010 Free Software Foundation, Inc. Written by Bruno Haible , 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 . */ /* Get declarations of the Win32 API functions. */ #define WIN32_LEAN_AND_MEAN #include /* Get _get_osfhandle() and _open_osfhandle(). */ #include #include #include #include #include #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; }