| 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; |