GDB (xrefs)
linux-waitpid.c
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1 /* Wrapper implementation for waitpid for GNU/Linux (LWP layer).
2 
3  Copyright (C) 2001-2015 Free Software Foundation, Inc.
4 
5  This file is part of GDB.
6 
7  This program is free software; you can redistribute it and/or modify
8  it under the terms of the GNU General Public License as published by
9  the Free Software Foundation; either version 3 of the License, or
10  (at your option) any later version.
11 
12  This program is distributed in the hope that it will be useful,
13  but WITHOUT ANY WARRANTY; without even the implied warranty of
14  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  GNU General Public License for more details.
16 
17  You should have received a copy of the GNU General Public License
18  along with this program. If not, see <http://www.gnu.org/licenses/>. */
19 
20 #include "common-defs.h"
21 
22 #ifdef GDBSERVER
23 /* FIXME: server.h is required for the definition of debug_threads
24  which is used in the gdbserver-specific debug printing in
25  linux_debug. This code should be made available to GDB also,
26  but the lack of a suitable flag to enable it prevents this. */
27 #include "server.h"
28 #endif
29 
30 #include "linux-nat.h"
31 #include "linux-waitpid.h"
32 #include "gdb_wait.h"
33 
34 /* Print debugging output based on the format string FORMAT and
35  its parameters. */
36 
37 static inline void
38 linux_debug (const char *format, ...)
39 {
40 #ifdef GDBSERVER
41  if (debug_threads)
42  {
43  va_list args;
44  va_start (args, format);
45  vfprintf (stderr, format, args);
46  va_end (args);
47  }
48 #endif
49 }
50 
51 /* Convert wait status STATUS to a string. Used for printing debug
52  messages only. */
53 
54 char *
56 {
57  static char buf[64];
58 
59  if (WIFSTOPPED (status))
60  {
61  if (WSTOPSIG (status) == SYSCALL_SIGTRAP)
62  snprintf (buf, sizeof (buf), "%s (stopped at syscall)",
63  strsignal (SIGTRAP));
64  else
65  snprintf (buf, sizeof (buf), "%s (stopped)",
66  strsignal (WSTOPSIG (status)));
67  }
68  else if (WIFSIGNALED (status))
69  snprintf (buf, sizeof (buf), "%s (terminated)",
70  strsignal (WTERMSIG (status)));
71  else
72  snprintf (buf, sizeof (buf), "%d (exited)", WEXITSTATUS (status));
73 
74  return buf;
75 }
76 
77 /* Wrapper function for waitpid which handles EINTR, and emulates
78  __WALL for systems where that is not available. */
79 
80 int
81 my_waitpid (int pid, int *status, int flags)
82 {
83  int ret, out_errno;
84 
85  linux_debug ("my_waitpid (%d, 0x%x)\n", pid, flags);
86 
87  if (flags & __WALL)
88  {
89  sigset_t block_mask, org_mask, wake_mask;
90  int wnohang;
91 
92  wnohang = (flags & WNOHANG) != 0;
93  flags &= ~(__WALL | __WCLONE);
94 
95  if (!wnohang)
96  {
97  flags |= WNOHANG;
98 
99  /* Block all signals while here. This avoids knowing about
100  LinuxThread's signals. */
101  sigfillset (&block_mask);
102  sigprocmask (SIG_BLOCK, &block_mask, &org_mask);
103 
104  /* ... except during the sigsuspend below. */
105  sigemptyset (&wake_mask);
106  }
107 
108  while (1)
109  {
110  /* Since all signals are blocked, there's no need to check
111  for EINTR here. */
112  ret = waitpid (pid, status, flags);
113  out_errno = errno;
114 
115  if (ret == -1 && out_errno != ECHILD)
116  break;
117  else if (ret > 0)
118  break;
119 
120  if (flags & __WCLONE)
121  {
122  /* We've tried both flavors now. If WNOHANG is set,
123  there's nothing else to do, just bail out. */
124  if (wnohang)
125  break;
126 
127  linux_debug ("blocking\n");
128 
129  /* Block waiting for signals. */
130  sigsuspend (&wake_mask);
131  }
132  flags ^= __WCLONE;
133  }
134 
135  if (!wnohang)
136  sigprocmask (SIG_SETMASK, &org_mask, NULL);
137  }
138  else
139  {
140  do
141  ret = waitpid (pid, status, flags);
142  while (ret == -1 && errno == EINTR);
143  out_errno = errno;
144  }
145 
146  linux_debug ("my_waitpid (%d, 0x%x): status(%x), %d\n",
147  pid, flags, (ret > 0 && status != NULL) ? *status : -1, ret);
148 
149  errno = out_errno;
150  return ret;
151 }
#define WNOHANG
Definition: gdb_wait.h:102
#define SYSCALL_SIGTRAP
Definition: linux-nat.h:31
#define __WCLONE
Definition: gdb_wait.h:110
mach_port_t kern_return_t mach_port_t msgports mach_port_t kern_return_t pid_t pid mach_port_t kern_return_t mach_port_t task mach_port_t kern_return_t int flags
Definition: gnu-nat.c:1885
#define WSTOPSIG
Definition: gdb_wait.h:75
#define WTERMSIG(w)
Definition: gdb_wait.h:71
mach_port_t mach_port_t name mach_port_t mach_port_t name error_t int status
Definition: gnu-nat.c:1816
static void linux_debug(const char *format,...)
Definition: linux-waitpid.c:38
#define WEXITSTATUS(w)
Definition: gdb_wait.h:67
char * status_to_str(int status)
Definition: linux-waitpid.c:55
#define __WALL
Definition: linux-ptrace.h:96
#define WIFSTOPPED(w)
Definition: gdb_wait.h:62
int my_waitpid(int pid, int *status, int flags)
Definition: linux-waitpid.c:81
#define WIFSIGNALED(w)
Definition: gdb_wait.h:48
mach_port_t mach_port_t name mach_port_t mach_port_t name error_t int int rusage_t pid_t pid
Definition: gnu-nat.c:1818