1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
|
/* Copyright (C) 1991, 1992, 1993, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <errno.h>
#include <stddef.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <fcntl.h>
#define SH_PATH "/bin/sh" /* Shell to run. */
#define SH_NAME "sh" /* Name to give it. */
/* Structure describing a popen child. */
struct child
{
pid_t pid; /* PID of the child. */
__ptr_t cookie; /* Original cookie from fdopen. */
__io_functions funcs; /* Original functions from fdopen. */
};
/* io_functions for pipe streams.
These all simply call the corresponding
original function with the original cookie. */
#define FUNC(type, name, args) \
static type __CONCAT(child_,name) args __CONCAT(name,decl) \
{ \
struct child *c = (struct child *) cookie; \
{ \
__ptr_t cookie = c->cookie; \
return (*c->funcs.__CONCAT(__,name)) args; \
} \
}
#define readdecl void *cookie; register char *buf; register size_t n;
FUNC (int, read, (cookie, buf, n))
#define writedecl void *cookie; register const char *buf; register size_t n;
FUNC (int, write, (cookie, buf, n))
#define seekdecl void *cookie; fpos_t *pos; int whence;
FUNC (int, seek, (cookie, pos, whence))
#define closedecl void *cookie;
FUNC (int, close, (cookie))
#define filenodecl void *cookie;
FUNC (int, fileno, (cookie))
static const __io_functions child_funcs
= { child_read, child_write, child_seek, child_close, child_fileno };
/* Open a new stream that is a one-way pipe to a
child process running the given shell command. */
FILE *
popen (command, mode)
const char *command;
const char *mode;
{
pid_t pid;
int pipedes[2];
FILE *stream;
struct child *child;
if (command == NULL || mode == NULL || (*mode != 'r' && *mode != 'w'))
{
__set_errno (EINVAL);
return NULL;
}
/* Create the pipe. */
if (pipe (pipedes) < 0)
return NULL;
/* Fork off the child. */
pid = __vfork ();
if (pid == (pid_t) -1)
{
/* The fork failed. */
(void) close (pipedes[0]);
(void) close (pipedes[1]);
return NULL;
}
else if (pid == (pid_t) 0)
{
/* We are the child side. Make the write side of
the pipe be stdin or the read side be stdout. */
const char *new_argv[4];
if ((*mode == 'w' ? dup2(pipedes[STDIN_FILENO], STDIN_FILENO) :
dup2 (pipedes[STDOUT_FILENO], STDOUT_FILENO)) < 0)
_exit (127);
/* Close the pipe descriptors. */
(void) close (pipedes[STDIN_FILENO]);
(void) close (pipedes[STDOUT_FILENO]);
/* Exec the shell. */
new_argv[0] = SH_NAME;
new_argv[1] = "-c";
new_argv[2] = command;
new_argv[3] = NULL;
(void) execve (SH_PATH, (char *const *) new_argv, environ);
/* Die if it failed. */
_exit (127);
}
/* We are the parent side. */
/* Close the irrelevant side of the pipe and open the relevant side as a
new stream. Mark our side of the pipe to close on exec, so new children
won't see it. */
if (*mode == 'r')
{
(void) close (pipedes[STDOUT_FILENO]);
(void) fcntl (pipedes[STDIN_FILENO], F_SETFD, FD_CLOEXEC);
stream = fdopen (pipedes[STDIN_FILENO], mode);
}
else
{
(void) close (pipedes[STDIN_FILENO]);
(void) fcntl (pipedes[STDOUT_FILENO], F_SETFD, FD_CLOEXEC);
stream = fdopen (pipedes[STDOUT_FILENO], mode);
}
if (stream == NULL)
goto error;
child = (struct child *) malloc (sizeof (struct child));
if (child == NULL)
goto error;
{
/* Make sure STREAM has its functions set before
we try to squirrel them away in CHILD. */
extern void __stdio_check_funcs __P ((FILE *));
__stdio_check_funcs (stream);
}
child->pid = pid;
child->cookie = stream->__cookie;
child->funcs = stream->__io_funcs;
stream->__cookie = (void *) child;
stream->__io_funcs = child_funcs;
stream->__ispipe = 1;
return stream;
error:
{
/* The stream couldn't be opened or the child structure couldn't be
allocated. Kill the child and close the other side of the pipe. */
int save = errno;
(void) kill (pid, SIGKILL);
if (stream == NULL)
(void) close (pipedes[*mode == 'r' ? STDOUT_FILENO : STDIN_FILENO]);
else
(void) fclose (stream);
#ifndef NO_WAITPID
(void) waitpid (pid, (int *) NULL, 0);
#else
{
pid_t dead;
do
dead = wait ((int *) NULL);
while (dead > 0 && dead != pid);
}
#endif
__set_errno (save);
return NULL;
}
}
/* Close a stream opened by popen and return its status.
Returns -1 if the stream was not opened by popen. */
int
pclose (stream)
register FILE *stream;
{
struct child *c;
pid_t pid, dead;
int status;
if (!__validfp (stream) || !stream->__ispipe)
{
__set_errno (EINVAL);
return -1;
}
c = (struct child *) stream->__cookie;
pid = c->pid;
stream->__cookie = c->cookie;
stream->__io_funcs = c->funcs;
free ((void *) c);
stream->__ispipe = 0;
if (fclose (stream))
return -1;
#ifndef NO_WAITPID
dead = waitpid (pid, &status, 0);
#else
do
dead = wait (&status);
while (dead > 0 && dead != pid);
#endif
if (dead != pid)
status = -1;
return status;
}
|
