Merge "debuggerd: simplify output handling"

This commit is contained in:
Christopher Ferris 2023-05-22 19:31:45 +00:00 committed by Gerrit Code Review
commit 34de747570
2 changed files with 11 additions and 24 deletions

View file

@ -276,6 +276,13 @@ bool debuggerd_trigger_dump(pid_t tid, DebuggerdDumpType dump_type, unsigned int
return false;
}
// WARNING: It's not possible to replace the below with a splice call.
// Due to the way debuggerd does many small writes across the pipe,
// this would cause splice to copy a page for each write. The second
// pipe fills up based on the number of pages being copied, even
// though there is not much data being transferred per page. When
// the second pipe is full, everything stops since there is nothing
// reading the second pipe to clear it.
char buf[1024];
rc = TEMP_FAILURE_RETRY(read(pipe_read.get(), buf, sizeof(buf)));
if (rc == 0) {

View file

@ -41,22 +41,6 @@ static void usage(int exit_code) {
_exit(exit_code);
}
static std::thread spawn_redirect_thread(unique_fd fd) {
return std::thread([fd{ std::move(fd) }]() {
while (true) {
char buf[BUFSIZ];
ssize_t rc = TEMP_FAILURE_RETRY(read(fd.get(), buf, sizeof(buf)));
if (rc <= 0) {
return;
}
if (!android::base::WriteFully(STDOUT_FILENO, buf, rc)) {
return;
}
}
});
}
int main(int argc, char* argv[]) {
if (argc <= 1) usage(0);
if (argc > 3) usage(1);
@ -107,14 +91,11 @@ int main(int argc, char* argv[]) {
}
}
unique_fd piperead, pipewrite;
if (!Pipe(&piperead, &pipewrite)) {
err(1, "failed to create pipe");
unique_fd output_fd(fcntl(STDOUT_FILENO, F_DUPFD_CLOEXEC, 0));
if (output_fd.get() == -1) {
err(1, "failed to fcntl dup stdout");
}
std::thread redirect_thread = spawn_redirect_thread(std::move(piperead));
if (!debuggerd_trigger_dump(proc_info.pid, dump_type, 0, std::move(pipewrite))) {
redirect_thread.join();
if (!debuggerd_trigger_dump(proc_info.pid, dump_type, 0, std::move(output_fd))) {
if (pid == proc_info.pid) {
errx(1, "failed to dump process %d", pid);
} else {
@ -122,6 +103,5 @@ int main(int argc, char* argv[]) {
}
}
redirect_thread.join();
return 0;
}