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1 | /* GNU/Linux native-dependent code common to multiple platforms. |
2 | Copyright (C) 2003 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GDB. | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program; if not, write to the Free Software | |
18 | Foundation, Inc., 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | #include "defs.h" | |
22 | #include "inferior.h" | |
23 | #include "target.h" | |
24 | ||
25 | #include "gdb_wait.h" | |
26 | #include <sys/ptrace.h> | |
27 | ||
28 | /* If the system headers did not provide the constants, hard-code the normal | |
29 | values. */ | |
30 | #ifndef PTRACE_EVENT_FORK | |
31 | ||
32 | #define PTRACE_SETOPTIONS 0x4200 | |
33 | #define PTRACE_GETEVENTMSG 0x4201 | |
34 | ||
35 | /* options set using PTRACE_SETOPTIONS */ | |
36 | #define PTRACE_O_TRACESYSGOOD 0x00000001 | |
37 | #define PTRACE_O_TRACEFORK 0x00000002 | |
38 | #define PTRACE_O_TRACEVFORK 0x00000004 | |
39 | #define PTRACE_O_TRACECLONE 0x00000008 | |
40 | #define PTRACE_O_TRACEEXEC 0x00000010 | |
41 | ||
42 | /* Wait extended result codes for the above trace options. */ | |
43 | #define PTRACE_EVENT_FORK 1 | |
44 | #define PTRACE_EVENT_VFORK 2 | |
45 | #define PTRACE_EVENT_CLONE 3 | |
46 | #define PTRACE_EVENT_EXEC 4 | |
47 | ||
48 | #endif /* PTRACE_EVENT_FORK */ | |
49 | ||
50 | /* We can't always assume that this flag is available, but all systems | |
51 | with the ptrace event handlers also have __WALL, so it's safe to use | |
52 | here. */ | |
53 | #ifndef __WALL | |
54 | #define __WALL 0x40000000 /* Wait for any child. */ | |
55 | #endif | |
56 | ||
57 | /* This variable is a tri-state flag: -1 for unknown, 0 if PTRACE_O_TRACEFORK | |
58 | can not be used, 1 if it can. */ | |
59 | ||
60 | static int linux_supports_tracefork_flag = -1; | |
61 | ||
62 | \f | |
63 | /* A helper function for linux_test_for_tracefork, called after fork (). */ | |
64 | ||
65 | static void | |
66 | linux_tracefork_child (void) | |
67 | { | |
68 | int ret; | |
69 | ||
70 | ptrace (PTRACE_TRACEME, 0, 0, 0); | |
71 | kill (getpid (), SIGSTOP); | |
72 | fork (); | |
73 | exit (0); | |
74 | } | |
75 | ||
76 | /* Determine if PTRACE_O_TRACEFORK can be used to follow fork events. We | |
77 | create a child process, attach to it, use PTRACE_SETOPTIONS to enable | |
78 | fork tracing, and let it fork. If the process exits, we assume that | |
79 | we can't use TRACEFORK; if we get the fork notification, and we can | |
80 | extract the new child's PID, then we assume that we can. */ | |
81 | ||
82 | static void | |
83 | linux_test_for_tracefork (void) | |
84 | { | |
85 | int child_pid, ret, status; | |
86 | long second_pid; | |
87 | ||
88 | child_pid = fork (); | |
89 | if (child_pid == -1) | |
90 | perror_with_name ("linux_test_for_tracefork: fork"); | |
91 | ||
92 | if (child_pid == 0) | |
93 | linux_tracefork_child (); | |
94 | ||
95 | ret = waitpid (child_pid, &status, 0); | |
96 | if (ret == -1) | |
97 | perror_with_name ("linux_test_for_tracefork: waitpid"); | |
98 | else if (ret != child_pid) | |
99 | error ("linux_test_for_tracefork: waitpid: unexpected result %d.", ret); | |
100 | if (! WIFSTOPPED (status)) | |
101 | error ("linux_test_for_tracefork: waitpid: unexpected status %d.", status); | |
102 | ||
103 | linux_supports_tracefork_flag = 0; | |
104 | ||
105 | ret = ptrace (PTRACE_SETOPTIONS, child_pid, 0, PTRACE_O_TRACEFORK); | |
106 | if (ret != 0) | |
107 | { | |
108 | ptrace (PTRACE_KILL, child_pid, 0, 0); | |
109 | waitpid (child_pid, &status, 0); | |
110 | return; | |
111 | } | |
112 | ||
113 | ptrace (PTRACE_CONT, child_pid, 0, 0); | |
114 | ret = waitpid (child_pid, &status, 0); | |
115 | if (ret == child_pid && WIFSTOPPED (status) | |
116 | && status >> 16 == PTRACE_EVENT_FORK) | |
117 | { | |
118 | second_pid = 0; | |
119 | ret = ptrace (PTRACE_GETEVENTMSG, child_pid, 0, &second_pid); | |
120 | if (ret == 0 && second_pid != 0) | |
121 | { | |
122 | int second_status; | |
123 | ||
124 | linux_supports_tracefork_flag = 1; | |
125 | waitpid (second_pid, &second_status, 0); | |
126 | ptrace (PTRACE_DETACH, second_pid, 0, 0); | |
127 | } | |
128 | } | |
129 | ||
130 | if (WIFSTOPPED (status)) | |
131 | { | |
132 | ptrace (PTRACE_DETACH, child_pid, 0, 0); | |
133 | waitpid (child_pid, &status, 0); | |
134 | } | |
135 | } | |
136 | ||
137 | /* Return non-zero iff we have tracefork functionality available. | |
138 | This function also sets linux_supports_tracefork_flag. */ | |
139 | ||
140 | static int | |
141 | linux_supports_tracefork (void) | |
142 | { | |
143 | if (linux_supports_tracefork_flag == -1) | |
144 | linux_test_for_tracefork (); | |
145 | return linux_supports_tracefork_flag; | |
146 | } | |
147 | ||
148 | \f | |
149 | int | |
150 | child_insert_fork_catchpoint (int pid) | |
151 | { | |
152 | if (linux_supports_tracefork ()) | |
153 | error ("Fork catchpoints have not been implemented yet."); | |
154 | else | |
155 | error ("Your system does not support fork catchpoints."); | |
156 | } | |
157 | ||
158 | int | |
159 | child_insert_vfork_catchpoint (int pid) | |
160 | { | |
161 | if (linux_supports_tracefork ()) | |
162 | error ("Vfork catchpoints have not been implemented yet."); | |
163 | else | |
164 | error ("Your system does not support vfork catchpoints."); | |
165 | } | |
166 | ||
167 | int | |
168 | child_insert_exec_catchpoint (int pid) | |
169 | { | |
170 | if (linux_supports_tracefork ()) | |
171 | error ("Exec catchpoints have not been implemented yet."); | |
172 | else | |
173 | error ("Your system does not support exec catchpoints."); | |
174 | } | |
175 | ||
176 |