1 /* Auxiliary functions for the creation of subprocesses. OS/2 kLIBC API.
2 Copyright (C) 2001, 2003-2021 Free Software Foundation, Inc.
3 Written by Bruno Haible <bruno@clisp.org>, 2003.
4
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.
9
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.
14
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/>. */
17
18 #include <config.h>
19
20 /* Specification. */
21 #include "os2-spawn.h"
22
23 /* Get _open_osfhandle(). */
24 #include <io.h>
25
26 #include <stdbool.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <unistd.h>
30 #include <errno.h>
31
32 #include "cloexec.h"
33 #include "error.h"
34 #include "gettext.h"
35
36 #define _(str) gettext (str)
37
38
39 /* Duplicates a file handle, making the copy uninheritable.
40 Returns -1 for a file handle that is equivalent to closed. */
41 static int
dup_noinherit(int fd)42 dup_noinherit (int fd)
43 {
44 fd = dup_cloexec (fd);
45 if (fd < 0 && errno == EMFILE)
46 error (EXIT_FAILURE, errno, _("_open_osfhandle failed"));
47
48 return fd;
49 }
50
51 /* Returns a file descriptor equivalent to FD, except that the resulting file
52 descriptor is none of STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO.
53 FD must be open and non-inheritable. The result will be non-inheritable as
54 well.
55 If FD < 0, FD itself is returned. */
56 static int
fd_safer_noinherit(int fd)57 fd_safer_noinherit (int fd)
58 {
59 if (STDIN_FILENO <= fd && fd <= STDERR_FILENO)
60 {
61 /* The recursion depth is at most 3. */
62 int nfd = fd_safer_noinherit (dup_noinherit (fd));
63 int saved_errno = errno;
64 close (fd);
65 errno = saved_errno;
66 return nfd;
67 }
68 return fd;
69 }
70
71 int
dup_safer_noinherit(int fd)72 dup_safer_noinherit (int fd)
73 {
74 return fd_safer_noinherit (dup_noinherit (fd));
75 }
76
77 void
undup_safer_noinherit(int tempfd,int origfd)78 undup_safer_noinherit (int tempfd, int origfd)
79 {
80 if (tempfd >= 0)
81 {
82 if (dup2 (tempfd, origfd) < 0)
83 error (EXIT_FAILURE, errno, _("cannot restore fd %d: dup2 failed"),
84 origfd);
85 close (tempfd);
86 }
87 else
88 {
89 /* origfd was closed or open to no handle at all. Set it to a closed
90 state. This is (nearly) equivalent to the original state. */
91 close (origfd);
92 }
93 }
94
95 const char **
prepare_spawn(const char * const * argv,char ** mem_to_free)96 prepare_spawn (const char * const *argv, char **mem_to_free)
97 {
98 size_t argc;
99 const char **new_argv;
100 size_t i;
101
102 /* Count number of arguments. */
103 for (argc = 0; argv[argc] != NULL; argc++)
104 ;
105
106 /* Allocate new argument vector. */
107 new_argv = (const char **) malloc ((1 + argc + 1) * sizeof (const char *));
108 if (new_argv == NULL)
109 return NULL;
110
111 /* Add an element upfront that can be used when argv[0] turns out to be a
112 script, not a program.
113 On Unix, this would be "/bin/sh". */
114 new_argv[0] = "sh.exe";
115
116 /* Put quoted arguments into the new argument vector. */
117 size_t needed_size = 0;
118 for (i = 0; i < argc; i++)
119 {
120 const char *string = argv[i];
121 const char *quoted_string = (string[0] == '\0' ? "\"\"" : string);
122 size_t length = strlen (quoted_string);
123 needed_size += length + 1;
124 }
125
126 char *mem;
127 if (needed_size == 0)
128 mem = NULL;
129 else
130 {
131 mem = (char *) malloc (needed_size);
132 if (mem == NULL)
133 {
134 /* Memory allocation failure. */
135 free (new_argv);
136 errno = ENOMEM;
137 return NULL;
138 }
139 }
140 *mem_to_free = mem;
141
142 for (i = 0; i < argc; i++)
143 {
144 const char *string = argv[i];
145
146 new_argv[1 + i] = mem;
147 const char *quoted_string = (string[0] == '\0' ? "\"\"" : string);
148 size_t length = strlen (quoted_string);
149 memcpy (mem, quoted_string, length + 1);
150 mem += length + 1;
151 }
152 new_argv[1 + argc] = NULL;
153
154 return new_argv;
155 }
156