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Utils: Don't raise SIGSTOP in the process stub

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Previously, the starting inferior was sent a SIGSTOP to avoid
progress before the debugger could attach.

However, these signals are then also visible in the debugger and
need to be ignored as part of the startup handling in Creator.

The waiting effect can be achieved less intrusively by waiting
on a pipe read between fork() and exec().

Task-number: QTCREATORBUG-25073
Task-number: QTCREATORBUG-25082
Task-number: QTCREATORBUG-25227
Change-Id: Ie70b9eb5ea865f85411c26b0dbf377a019fec8d5
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
This commit is contained in:
hjk
2021-02-25 12:38:44 +01:00
parent d37f6648f3
commit 89646aadce
7 changed files with 50 additions and 41 deletions
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36
src/libs/utils/process_stub_unix.c
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@@ -57,6 +57,7 @@ extern char **environ;
static int qtcFd;
static char *sleepMsg;
static int chldPipe[2];
static int blockingPipe[2];
static int isDebug;
static volatile int isDetached;
static volatile int chldPid;
@@ -236,10 +237,21 @@ int main(int argc, char *argv[])
perror("Cannot create status pipe");
doExit(3);
}
/* The debugged program is not supposed to inherit these handles. But we cannot
* close the writing end before calling exec(). Just handle both ends the same way ... */
fcntl(chldPipe[0], F_SETFD, FD_CLOEXEC);
fcntl(chldPipe[1], F_SETFD, FD_CLOEXEC);
if (isDebug) {
/* Create execution start notification pipe. The child waits on this until
the parent writes to it, triggered by an 'c' message from Creator */
if (pipe(blockingPipe)) {
perror("Cannot create blocking pipe");
doExit(3);
}
}
switch ((chldPid = fork())) {
case -1:
perror("Cannot fork child process");
@@ -262,9 +274,15 @@ int main(int argc, char *argv[])
#ifdef __linux__
prctl(PR_SET_PTRACER, atoi(argv[ArgPid]));
#endif
/* Stop the child to allow the debugger to attach */
if (isDebug)
kill(chldPid, SIGSTOP);
/* Block to allow the debugger to attach */
if (isDebug) {
char buf;
int res = read(blockingPipe[0], &buf, 1);
if (res < 0)
perror("Could not read from blocking pipe");
close(blockingPipe[0]);
close(blockingPipe[1]);
}
if (env)
environ = env;
@@ -296,6 +314,7 @@ int main(int argc, char *argv[])
break;
} else {
int i;
char c = 'i';
for (i = 0; i < nbytes; ++i) {
switch (buffer[i]) {
case 'k':
@@ -305,13 +324,12 @@ int main(int argc, char *argv[])
kill(chldPid, SIGKILL);
}
break;
case 'i':
if (chldPid > 0) {
int res = kill(chldPid, SIGINT);
if (res)
perror("Stub could not interrupt inferior");
}
case 'c': {
int res = write(blockingPipe[1], &c, 1);
if (res < 0)
perror("Could not write to blocking pipe");
break;
}
case 'd':
isDetached = 1;
break;