1/* Capture output from a subprocess.
2 Copyright (C) 2017-2019 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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#include <support/capture_subprocess.h>
20
21#include <errno.h>
22#include <stdlib.h>
23#include <support/check.h>
24#include <support/xunistd.h>
25#include <support/xsocket.h>
26
27static void
28transfer (const char *what, struct pollfd *pfd, struct xmemstream *stream)
29{
30 if (pfd->revents != 0)
31 {
32 char buf[1024];
33 ssize_t ret = TEMP_FAILURE_RETRY (read (pfd->fd, buf, sizeof (buf)));
34 if (ret < 0)
35 {
36 support_record_failure ();
37 printf ("error: reading from subprocess %s: %m", what);
38 pfd->events = 0;
39 pfd->revents = 0;
40 }
41 else if (ret == 0)
42 {
43 /* EOF reached. Stop listening. */
44 pfd->events = 0;
45 pfd->revents = 0;
46 }
47 else
48 /* Store the data just read. */
49 TEST_VERIFY (fwrite (buf, ret, 1, stream->out) == 1);
50 }
51}
52
53struct support_capture_subprocess
54support_capture_subprocess (void (*callback) (void *), void *closure)
55{
56 struct support_capture_subprocess result;
57 xopen_memstream (&result.out);
58 xopen_memstream (&result.err);
59
60 int stdout_pipe[2];
61 xpipe (stdout_pipe);
62 TEST_VERIFY (stdout_pipe[0] > STDERR_FILENO);
63 TEST_VERIFY (stdout_pipe[1] > STDERR_FILENO);
64 int stderr_pipe[2];
65 xpipe (stderr_pipe);
66 TEST_VERIFY (stderr_pipe[0] > STDERR_FILENO);
67 TEST_VERIFY (stderr_pipe[1] > STDERR_FILENO);
68
69 TEST_VERIFY (fflush (stdout) == 0);
70 TEST_VERIFY (fflush (stderr) == 0);
71
72 pid_t pid = xfork ();
73 if (pid == 0)
74 {
75 xclose (stdout_pipe[0]);
76 xclose (stderr_pipe[0]);
77 xdup2 (stdout_pipe[1], STDOUT_FILENO);
78 xdup2 (stderr_pipe[1], STDERR_FILENO);
79 xclose (stdout_pipe[1]);
80 xclose (stderr_pipe[1]);
81 callback (closure);
82 _exit (0);
83 }
84 xclose (stdout_pipe[1]);
85 xclose (stderr_pipe[1]);
86
87 struct pollfd fds[2] =
88 {
89 { .fd = stdout_pipe[0], .events = POLLIN },
90 { .fd = stderr_pipe[0], .events = POLLIN },
91 };
92
93 do
94 {
95 xpoll (fds, 2, -1);
96 transfer ("stdout", &fds[0], &result.out);
97 transfer ("stderr", &fds[1], &result.err);
98 }
99 while (fds[0].events != 0 || fds[1].events != 0);
100 xclose (stdout_pipe[0]);
101 xclose (stderr_pipe[0]);
102
103 xfclose_memstream (&result.out);
104 xfclose_memstream (&result.err);
105 xwaitpid (pid, &result.status, 0);
106 return result;
107}
108
109void
110support_capture_subprocess_free (struct support_capture_subprocess *p)
111{
112 free (p->out.buffer);
113 free (p->err.buffer);
114}
115