[Pdbg] [PATCH v2 24/39] gdbserver: catch ctrl-C to clean up host state

[Nicholas Piggin]

Excerpts from Joel Stanley's message of May 3, 2022 5:13 pm:
> On Wed, 20 Apr 2022 at 06:51, Nicholas Piggin <npiggin at gmail.com> wrote:
>>
>> This allows gdbserver to clean up the host state gracefully after
>> a SIGINT. Later patches will add more host state cleanup.
>>
>> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
>> ---
>>  src/pdbgproxy.c | 24 ++++++++++++++++++++++--
>>  1 file changed, 22 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/pdbgproxy.c b/src/pdbgproxy.c
>> index 4572c689..ef8aa479 100644
>> --- a/src/pdbgproxy.c
>> +++ b/src/pdbgproxy.c
>> @@ -4,6 +4,7 @@
>>  #include <stdio.h>
>>  #include <stdlib.h>
>>  #include <string.h>
>> +#include <signal.h>
>>  #include <fcntl.h>
>>  #include <unistd.h>
>>  #include <sys/types.h>
>> @@ -640,12 +641,28 @@ static command_cb callbacks[LAST_CMD + 1] = {
>>         detach,
>>         NULL};
>>
>> -int gdbserver_start(struct pdbg_target *thread, struct pdbg_target *adu, uint16_t port)
>> +static volatile bool gdbserver_running = true;
> 
> volatile! Is this how we userspace?

I'm rusty but I think this is one of the few occasions you can use
volatile without either being wrong or having a compiler writer get
angry at you.

Thanks,
Nick

> 
> Reviewed-by: Joel Stanley <joel at jms.id.au>
> 
>> +
>> +static void SIGINT_handler(int sig)
>> +{
>> +       gdbserver_running = false;
>> +}
>> +
>> +static int gdbserver_start(struct pdbg_target *thread, struct pdbg_target *adu, uint16_t port)
>>  {
>>         int sock, i;
>> +       struct sigaction sa;
>>         struct sockaddr_in name;
>>         fd_set active_fd_set, read_fd_set;
>>
>> +       memset(&sa, 0, sizeof(sa));
>> +       sa.sa_handler = SIGINT_handler;
>> +       sa.sa_flags = SA_RESETHAND | SA_NODEFER;
>> +       if (sigaction(SIGINT, &sa, NULL) == -1) {
>> +               perror("sigaction");
>> +               return -1;
>> +       }
>> +
>>         parser_init(callbacks);
>>         thread_target = thread;
>>         adu_target = adu;
>> @@ -674,7 +691,7 @@ int gdbserver_start(struct pdbg_target *thread, struct pdbg_target *adu, uint16_
>>         FD_ZERO(&active_fd_set);
>>         FD_SET(sock, &active_fd_set);
>>
>> -       while (1) {
>> +       while (gdbserver_running) {
>>                 read_fd_set = active_fd_set;
>>                 timeout.tv_sec = 0;
>>                 timeout.tv_usec = poll_interval;
>> @@ -725,6 +742,8 @@ int gdbserver_start(struct pdbg_target *thread, struct pdbg_target *adu, uint16_
>>                 poll();
>>         }
>>
>> +       printf("gdbserver: got ctrl-C, cleaning up (second ctrl-C to kill immediately).\n");
>> +
>>         return 1;
>>  }
>>
>> @@ -776,6 +795,7 @@ static int gdbserver(uint16_t port)
>>         }
>>
>>         gdbserver_start(thread, adu, port);
>> +
>>         return 0;
>>  }
>>  #else
>> --
>> 2.35.1
>>
>> --
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>