1/* Capture output from a subprocess.
2 Copyright (C) 2017 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 int stderr_pipe[2];
63 xpipe (stderr_pipe);
64
65 TEST_VERIFY (fflush (stdout) == 0);
66 TEST_VERIFY (fflush (stderr) == 0);
67
68 pid_t pid = xfork ();
69 if (pid == 0)
70 {
71 xclose (stdout_pipe[0]);
72 xclose (stderr_pipe[0]);
73 xdup2 (stdout_pipe[1], STDOUT_FILENO);
74 xdup2 (stderr_pipe[1], STDERR_FILENO);
75 callback (closure);
76 _exit (0);
77 }
78 xclose (stdout_pipe[1]);
79 xclose (stderr_pipe[1]);
80
81 struct pollfd fds[2] =
82 {
83 { .fd = stdout_pipe[0], .events = POLLIN },
84 { .fd = stderr_pipe[0], .events = POLLIN },
85 };
86
87 do
88 {
89 xpoll (fds, 2, -1);
90 transfer ("stdout", &fds[0], &result.out);
91 transfer ("stderr", &fds[1], &result.err);
92 }
93 while (fds[0].events != 0 || fds[1].events != 0);
94 xclose (stdout_pipe[0]);
95 xclose (stderr_pipe[0]);
96
97 xfclose_memstream (&result.out);
98 xfclose_memstream (&result.err);
99 xwaitpid (pid, &result.status, 0);
100 return result;
101}
102
103void
104support_capture_subprocess_free (struct support_capture_subprocess *p)
105{
106 free (p->out.buffer);
107 free (p->err.buffer);
108}
109