1 | /* Copyright (C) 1993-2018 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | Written by Per Bothner <bothner@cygnus.com>. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library 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 GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. |
18 | |
19 | As a special exception, if you link the code in this file with |
20 | files compiled with a GNU compiler to produce an executable, |
21 | that does not cause the resulting executable to be covered by |
22 | the GNU Lesser General Public License. This exception does not |
23 | however invalidate any other reasons why the executable file |
24 | might be covered by the GNU Lesser General Public License. |
25 | This exception applies to code released by its copyright holders |
26 | in files containing the exception. */ |
27 | |
28 | #include "libioP.h" |
29 | #include <fcntl.h> |
30 | #include <signal.h> |
31 | #include <unistd.h> |
32 | #include <stdlib.h> |
33 | #include <shlib-compat.h> |
34 | #include <not-cancel.h> |
35 | #include <sys/types.h> |
36 | #include <sys/wait.h> |
37 | #include <kernel-features.h> |
38 | |
39 | struct _IO_proc_file |
40 | { |
41 | struct _IO_FILE_plus file; |
42 | /* Following fields must match those in class procbuf (procbuf.h) */ |
43 | _IO_pid_t pid; |
44 | struct _IO_proc_file *next; |
45 | }; |
46 | typedef struct _IO_proc_file _IO_proc_file; |
47 | |
48 | static const struct _IO_jump_t _IO_proc_jumps; |
49 | |
50 | static struct _IO_proc_file *proc_file_chain; |
51 | |
52 | #ifdef _IO_MTSAFE_IO |
53 | static _IO_lock_t proc_file_chain_lock = _IO_lock_initializer; |
54 | |
55 | static void |
56 | unlock (void *not_used) |
57 | { |
58 | _IO_lock_unlock (proc_file_chain_lock); |
59 | } |
60 | #endif |
61 | |
62 | _IO_FILE * |
63 | _IO_new_proc_open (_IO_FILE *fp, const char *command, const char *mode) |
64 | { |
65 | int read_or_write; |
66 | int parent_end, child_end; |
67 | int pipe_fds[2]; |
68 | _IO_pid_t child_pid; |
69 | |
70 | int do_read = 0; |
71 | int do_write = 0; |
72 | int do_cloexec = 0; |
73 | while (*mode != '\0') |
74 | switch (*mode++) |
75 | { |
76 | case 'r': |
77 | do_read = 1; |
78 | break; |
79 | case 'w': |
80 | do_write = 1; |
81 | break; |
82 | case 'e': |
83 | do_cloexec = 1; |
84 | break; |
85 | default: |
86 | errout: |
87 | __set_errno (EINVAL); |
88 | return NULL; |
89 | } |
90 | |
91 | if ((do_read ^ do_write) == 0) |
92 | goto errout; |
93 | |
94 | if (_IO_file_is_open (fp)) |
95 | return NULL; |
96 | |
97 | /* Atomically set the O_CLOEXEC flag for the pipe end used by the |
98 | child process (to avoid leaking the file descriptor in case of a |
99 | concurrent fork). This is later reverted in the child process. |
100 | When popen returns, the parent pipe end can be O_CLOEXEC or not, |
101 | depending on the 'e' open mode, but there is only one flag which |
102 | controls both descriptors. The parent end is adjusted below, |
103 | after creating the child process. (In the child process, the |
104 | parent end should be closed on execve, so O_CLOEXEC remains set |
105 | there.) */ |
106 | if (__pipe2 (pipe_fds, O_CLOEXEC) < 0) |
107 | return NULL; |
108 | |
109 | if (do_read) |
110 | { |
111 | parent_end = pipe_fds[0]; |
112 | child_end = pipe_fds[1]; |
113 | read_or_write = _IO_NO_WRITES; |
114 | } |
115 | else |
116 | { |
117 | parent_end = pipe_fds[1]; |
118 | child_end = pipe_fds[0]; |
119 | read_or_write = _IO_NO_READS; |
120 | } |
121 | |
122 | ((_IO_proc_file *) fp)->pid = child_pid = __fork (); |
123 | if (child_pid == 0) |
124 | { |
125 | int child_std_end = do_read ? 1 : 0; |
126 | struct _IO_proc_file *p; |
127 | |
128 | if (child_end != child_std_end) |
129 | __dup2 (child_end, child_std_end); |
130 | else |
131 | /* The descriptor is already the one we will use. But it must |
132 | not be marked close-on-exec. Undo the effects. */ |
133 | __fcntl (child_end, F_SETFD, 0); |
134 | /* POSIX.2: "popen() shall ensure that any streams from previous |
135 | popen() calls that remain open in the parent process are closed |
136 | in the new child process." */ |
137 | for (p = proc_file_chain; p; p = p->next) |
138 | { |
139 | int fd = _IO_fileno ((_IO_FILE *) p); |
140 | |
141 | /* If any stream from previous popen() calls has fileno |
142 | child_std_end, it has been already closed by the dup2 syscall |
143 | above. */ |
144 | if (fd != child_std_end) |
145 | __close_nocancel (fd); |
146 | } |
147 | |
148 | execl ("/bin/sh" , "sh" , "-c" , command, (char *) 0); |
149 | _exit (127); |
150 | } |
151 | __close_nocancel (child_end); |
152 | if (child_pid < 0) |
153 | { |
154 | __close_nocancel (parent_end); |
155 | return NULL; |
156 | } |
157 | |
158 | if (!do_cloexec) |
159 | /* Undo the effects of the pipe2 call which set the |
160 | close-on-exec flag. */ |
161 | __fcntl (parent_end, F_SETFD, 0); |
162 | |
163 | _IO_fileno (fp) = parent_end; |
164 | |
165 | /* Link into proc_file_chain. */ |
166 | #ifdef _IO_MTSAFE_IO |
167 | _IO_cleanup_region_start_noarg (unlock); |
168 | _IO_lock_lock (proc_file_chain_lock); |
169 | #endif |
170 | ((_IO_proc_file *) fp)->next = proc_file_chain; |
171 | proc_file_chain = (_IO_proc_file *) fp; |
172 | #ifdef _IO_MTSAFE_IO |
173 | _IO_lock_unlock (proc_file_chain_lock); |
174 | _IO_cleanup_region_end (0); |
175 | #endif |
176 | |
177 | _IO_mask_flags (fp, read_or_write, _IO_NO_READS|_IO_NO_WRITES); |
178 | return fp; |
179 | } |
180 | |
181 | _IO_FILE * |
182 | _IO_new_popen (const char *command, const char *mode) |
183 | { |
184 | struct locked_FILE |
185 | { |
186 | struct _IO_proc_file fpx; |
187 | #ifdef _IO_MTSAFE_IO |
188 | _IO_lock_t lock; |
189 | #endif |
190 | } *new_f; |
191 | _IO_FILE *fp; |
192 | |
193 | new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE)); |
194 | if (new_f == NULL) |
195 | return NULL; |
196 | #ifdef _IO_MTSAFE_IO |
197 | new_f->fpx.file.file._lock = &new_f->lock; |
198 | #endif |
199 | fp = &new_f->fpx.file.file; |
200 | _IO_init_internal (fp, 0); |
201 | _IO_JUMPS (&new_f->fpx.file) = &_IO_proc_jumps; |
202 | _IO_new_file_init_internal (&new_f->fpx.file); |
203 | #if !_IO_UNIFIED_JUMPTABLES |
204 | new_f->fpx.file.vtable = NULL; |
205 | #endif |
206 | if (_IO_new_proc_open (fp, command, mode) != NULL) |
207 | return (_IO_FILE *) &new_f->fpx.file; |
208 | _IO_un_link (&new_f->fpx.file); |
209 | free (new_f); |
210 | return NULL; |
211 | } |
212 | |
213 | int |
214 | _IO_new_proc_close (_IO_FILE *fp) |
215 | { |
216 | /* This is not name-space clean. FIXME! */ |
217 | int wstatus; |
218 | _IO_proc_file **ptr = &proc_file_chain; |
219 | _IO_pid_t wait_pid; |
220 | int status = -1; |
221 | |
222 | /* Unlink from proc_file_chain. */ |
223 | #ifdef _IO_MTSAFE_IO |
224 | _IO_cleanup_region_start_noarg (unlock); |
225 | _IO_lock_lock (proc_file_chain_lock); |
226 | #endif |
227 | for ( ; *ptr != NULL; ptr = &(*ptr)->next) |
228 | { |
229 | if (*ptr == (_IO_proc_file *) fp) |
230 | { |
231 | *ptr = (*ptr)->next; |
232 | status = 0; |
233 | break; |
234 | } |
235 | } |
236 | #ifdef _IO_MTSAFE_IO |
237 | _IO_lock_unlock (proc_file_chain_lock); |
238 | _IO_cleanup_region_end (0); |
239 | #endif |
240 | |
241 | if (status < 0 || __close_nocancel (_IO_fileno(fp)) < 0) |
242 | return -1; |
243 | /* POSIX.2 Rationale: "Some historical implementations either block |
244 | or ignore the signals SIGINT, SIGQUIT, and SIGHUP while waiting |
245 | for the child process to terminate. Since this behavior is not |
246 | described in POSIX.2, such implementations are not conforming." */ |
247 | do |
248 | { |
249 | wait_pid = __waitpid_nocancel (((_IO_proc_file *) fp)->pid, &wstatus, 0); |
250 | } |
251 | while (wait_pid == -1 && errno == EINTR); |
252 | if (wait_pid == -1) |
253 | return -1; |
254 | return wstatus; |
255 | } |
256 | |
257 | static const struct _IO_jump_t _IO_proc_jumps libio_vtable = { |
258 | JUMP_INIT_DUMMY, |
259 | JUMP_INIT(finish, _IO_new_file_finish), |
260 | JUMP_INIT(overflow, _IO_new_file_overflow), |
261 | JUMP_INIT(underflow, _IO_new_file_underflow), |
262 | JUMP_INIT(uflow, _IO_default_uflow), |
263 | JUMP_INIT(pbackfail, _IO_default_pbackfail), |
264 | JUMP_INIT(xsputn, _IO_new_file_xsputn), |
265 | JUMP_INIT(xsgetn, _IO_default_xsgetn), |
266 | JUMP_INIT(seekoff, _IO_new_file_seekoff), |
267 | JUMP_INIT(seekpos, _IO_default_seekpos), |
268 | JUMP_INIT(setbuf, _IO_new_file_setbuf), |
269 | JUMP_INIT(sync, _IO_new_file_sync), |
270 | JUMP_INIT(doallocate, _IO_file_doallocate), |
271 | JUMP_INIT(read, _IO_file_read), |
272 | JUMP_INIT(write, _IO_new_file_write), |
273 | JUMP_INIT(seek, _IO_file_seek), |
274 | JUMP_INIT(close, _IO_new_proc_close), |
275 | JUMP_INIT(stat, _IO_file_stat), |
276 | JUMP_INIT(showmanyc, _IO_default_showmanyc), |
277 | JUMP_INIT(imbue, _IO_default_imbue) |
278 | }; |
279 | |
280 | strong_alias (_IO_new_popen, __new_popen) |
281 | versioned_symbol (libc, _IO_new_popen, _IO_popen, GLIBC_2_1); |
282 | versioned_symbol (libc, __new_popen, popen, GLIBC_2_1); |
283 | versioned_symbol (libc, _IO_new_proc_open, _IO_proc_open, GLIBC_2_1); |
284 | versioned_symbol (libc, _IO_new_proc_close, _IO_proc_close, GLIBC_2_1); |
285 | |