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
|
Status: submitted for comments
2004-11-12 Daniel Jacobowitz <dan@debian.org>
* linux-nat.c (my_waitpid): New function.
(linux_test_for_tracefork): Make more robust and verbose. Take
an ORIGINAL_PID argument and test for PTRACE_SETOPTIONS first.
(linux_supports_tracefork, linux_supports_tracevforkdone): Take a PID
argument. Update calls to linux_test_for_tracefork.
(linux_enable_event_reporting, child_follow_fork)
(child_insert_fork_catchpoint, child_insert_vfork_catchpoint)
(child_insert_exec_catchpoint): Update calls to
linux_supports_tracefork and linux_supports_tracevforkdone.
Index: gdb-6.3/gdb/linux-nat.c
===================================================================
--- gdb-6.3.orig/gdb/linux-nat.c 2004-10-08 16:29:47.000000000 -0400
+++ gdb-6.3/gdb/linux-nat.c 2004-11-13 16:41:51.368720845 -0500
@@ -150,18 +150,47 @@ linux_tracefork_child (void)
exit (0);
}
-/* Determine if PTRACE_O_TRACEFORK can be used to follow fork events. We
+/* Wrapper function for waitpid which handles EINTR. */
+
+static int
+my_waitpid (int pid, int *status, int flags)
+{
+ int ret;
+ do
+ {
+ ret = waitpid (pid, status, flags);
+ }
+ while (ret == -1 && errno == EINTR);
+
+ return ret;
+}
+
+/* Determine if PTRACE_O_TRACEFORK can be used to follow fork events.
+
+ First, we try to enable fork tracing on ORIGINAL_PID. If this fails,
+ we know that the feature is not available. This may change the tracing
+ options for ORIGINAL_PID, but we'll be setting them shortly anyway.
+
+ However, if it succeeds, we don't know for sure that the feature is
+ available; old versions of PTRACE_SETOPTIONS ignored unknown options. We
create a child process, attach to it, use PTRACE_SETOPTIONS to enable
- fork tracing, and let it fork. If the process exits, we assume that
- we can't use TRACEFORK; if we get the fork notification, and we can
- extract the new child's PID, then we assume that we can. */
+ fork tracing, and let it fork. If the process exits, we assume that we
+ can't use TRACEFORK; if we get the fork notification, and we can extract
+ the new child's PID, then we assume that we can. */
static void
-linux_test_for_tracefork (void)
+linux_test_for_tracefork (int original_pid)
{
int child_pid, ret, status;
long second_pid;
+ linux_supports_tracefork_flag = 0;
+ linux_supports_tracevforkdone_flag = 0;
+
+ ret = ptrace (PTRACE_SETOPTIONS, original_pid, 0, PTRACE_O_TRACEFORK);
+ if (ret != 0)
+ return;
+
child_pid = fork ();
if (child_pid == -1)
perror_with_name ("linux_test_for_tracefork: fork");
@@ -169,7 +198,7 @@ linux_test_for_tracefork (void)
if (child_pid == 0)
linux_tracefork_child ();
- ret = waitpid (child_pid, &status, 0);
+ ret = my_waitpid (child_pid, &status, 0);
if (ret == -1)
perror_with_name ("linux_test_for_tracefork: waitpid");
else if (ret != child_pid)
@@ -177,13 +206,23 @@ linux_test_for_tracefork (void)
if (! WIFSTOPPED (status))
error ("linux_test_for_tracefork: waitpid: unexpected status %d.", status);
- linux_supports_tracefork_flag = 0;
-
ret = ptrace (PTRACE_SETOPTIONS, child_pid, 0, PTRACE_O_TRACEFORK);
if (ret != 0)
{
- ptrace (PTRACE_KILL, child_pid, 0, 0);
- waitpid (child_pid, &status, 0);
+ ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
+ if (ret != 0)
+ {
+ warning ("linux_test_for_tracefork: failed to kill child");
+ return;
+ }
+
+ ret = my_waitpid (child_pid, &status, 0);
+ if (ret != child_pid)
+ warning ("linux_test_for_tracefork: failed to wait for killed child");
+ else if (!WIFSIGNALED (status))
+ warning ("linux_test_for_tracefork: unexpected wait status 0x%x from "
+ "killed child", status);
+
return;
}
@@ -192,8 +231,12 @@ linux_test_for_tracefork (void)
PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORKDONE);
linux_supports_tracevforkdone_flag = (ret == 0);
- ptrace (PTRACE_CONT, child_pid, 0, 0);
- ret = waitpid (child_pid, &status, 0);
+ ret = ptrace (PTRACE_CONT, child_pid, 0, 0);
+ if (ret != 0)
+ warning ("linux_test_for_tracefork: failed to resume child");
+
+ ret = my_waitpid (child_pid, &status, 0);
+
if (ret == child_pid && WIFSTOPPED (status)
&& status >> 16 == PTRACE_EVENT_FORK)
{
@@ -204,34 +247,38 @@ linux_test_for_tracefork (void)
int second_status;
linux_supports_tracefork_flag = 1;
- waitpid (second_pid, &second_status, 0);
- ptrace (PTRACE_DETACH, second_pid, 0, 0);
+ my_waitpid (second_pid, &second_status, 0);
+ ret = ptrace (PTRACE_KILL, second_pid, 0, 0);
+ if (ret != 0)
+ warning ("linux_test_for_tracefork: failed to kill second child");
}
}
+ else
+ warning ("linux_test_for_tracefork: unexpected result from waitpid "
+ "(%d, status 0x%x)", ret, status);
- if (WIFSTOPPED (status))
- {
- ptrace (PTRACE_DETACH, child_pid, 0, 0);
- waitpid (child_pid, &status, 0);
- }
+ ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
+ if (ret != 0)
+ warning ("linux_test_for_tracefork: failed to kill child");
+ my_waitpid (child_pid, &status, 0);
}
/* Return non-zero iff we have tracefork functionality available.
This function also sets linux_supports_tracefork_flag. */
static int
-linux_supports_tracefork (void)
+linux_supports_tracefork (int pid)
{
if (linux_supports_tracefork_flag == -1)
- linux_test_for_tracefork ();
+ linux_test_for_tracefork (pid);
return linux_supports_tracefork_flag;
}
static int
-linux_supports_tracevforkdone (void)
+linux_supports_tracevforkdone (int pid)
{
if (linux_supports_tracefork_flag == -1)
- linux_test_for_tracefork ();
+ linux_test_for_tracefork (pid);
return linux_supports_tracevforkdone_flag;
}
@@ -242,12 +289,12 @@ linux_enable_event_reporting (ptid_t pti
int pid = ptid_get_pid (ptid);
int options;
- if (! linux_supports_tracefork ())
+ if (! linux_supports_tracefork (pid))
return;
options = PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK | PTRACE_O_TRACEEXEC
| PTRACE_O_TRACECLONE;
- if (linux_supports_tracevforkdone ())
+ if (linux_supports_tracevforkdone (pid))
options |= PTRACE_O_TRACEVFORKDONE;
/* Do not enable PTRACE_O_TRACEEXIT until GDB is more prepared to support
@@ -308,7 +355,8 @@ child_follow_fork (int follow_child)
if (has_vforked)
{
- if (linux_supports_tracevforkdone ())
+ gdb_assert (linux_supports_tracefork_flag >= 0);
+ if (linux_supports_tracevforkdone (0))
{
int status;
@@ -476,7 +524,7 @@ linux_handle_extended_wait (int pid, int
int
child_insert_fork_catchpoint (int pid)
{
- if (! linux_supports_tracefork ())
+ if (! linux_supports_tracefork (pid))
error ("Your system does not support fork catchpoints.");
return 0;
@@ -485,7 +533,7 @@ child_insert_fork_catchpoint (int pid)
int
child_insert_vfork_catchpoint (int pid)
{
- if (!linux_supports_tracefork ())
+ if (!linux_supports_tracefork (pid))
error ("Your system does not support vfork catchpoints.");
return 0;
@@ -494,7 +542,7 @@ child_insert_vfork_catchpoint (int pid)
int
child_insert_exec_catchpoint (int pid)
{
- if (!linux_supports_tracefork ())
+ if (!linux_supports_tracefork (pid))
error ("Your system does not support exec catchpoints.");
return 0;
|
