init: add stdio_to_kmsg option
Some services are not native android services and therefore don't log
via the normal mechanisms. This gives developers an option to have
their stdout/stderr logs sent directly to kmsg.
Test: see test prints to kernel log
Change-Id: I7973ea74d5cab3a90c2cd9a3d5de2266439d0c01
diff --git a/init/README.md b/init/README.md
index 423c6d1..29b972d 100644
--- a/init/README.md
+++ b/init/README.md
@@ -170,6 +170,8 @@
be changed by setting the "androidboot.console" kernel parameter. In
all cases the leading "/dev/" should be omitted, so "/dev/tty0" would be
specified as just "console tty0".
+ This option connects stdin, stdout, and stderr to the console. It is mutually exclusive with the
+ stdio_to_kmsg option, which only connects stdout and stderr to kmsg.
`critical`
> This is a device-critical service. If it exits more than four times in
@@ -313,6 +315,13 @@
seclabel or computed based on the service executable file security context.
For native executables see libcutils android\_get\_control\_socket().
+`stdio_to_kmsg`
+> Redirect stdout and stderr to /dev/kmsg_debug. This is useful for services that do not use native
+ Android logging during early boot and whose logs messages we want to capture. This is only enabled
+ when /dev/kmsg_debug is enabled, which is only enabled on userdebug and eng builds.
+ This is mutually exclusive with the console option, which additionally connects stdin to the
+ given console.
+
`timeout_period <seconds>`
> Provide a timeout after which point the service will be killed. The oneshot keyword is respected
here, so oneshot services do not automatically restart, however all other services will.
diff --git a/init/service_parser.cpp b/init/service_parser.cpp
index 45d1852..e7808a9 100644
--- a/init/service_parser.cpp
+++ b/init/service_parser.cpp
@@ -83,6 +83,9 @@
}
Result<void> ServiceParser::ParseConsole(std::vector<std::string>&& args) {
+ if (service_->proc_attr_.stdio_to_kmsg) {
+ return Error() << "'console' and 'stdio_to_kmsg' are mutually exclusive";
+ }
service_->flags_ |= SVC_CONSOLE;
service_->proc_attr_.console = args.size() > 1 ? "/dev/" + args[1] : "";
return {};
@@ -429,6 +432,14 @@
return {};
}
+Result<void> ServiceParser::ParseStdioToKmsg(std::vector<std::string>&& args) {
+ if (service_->flags_ & SVC_CONSOLE) {
+ return Error() << "'stdio_to_kmsg' and 'console' are mutually exclusive";
+ }
+ service_->proc_attr_.stdio_to_kmsg = true;
+ return {};
+}
+
// name type
Result<void> ServiceParser::ParseFile(std::vector<std::string>&& args) {
if (args[2] != "r" && args[2] != "w" && args[2] != "rw") {
@@ -514,6 +525,7 @@
{"shutdown", {1, 1, &ServiceParser::ParseShutdown}},
{"sigstop", {0, 0, &ServiceParser::ParseSigstop}},
{"socket", {3, 6, &ServiceParser::ParseSocket}},
+ {"stdio_to_kmsg", {0, 0, &ServiceParser::ParseStdioToKmsg}},
{"timeout_period", {1, 1, &ServiceParser::ParseTimeoutPeriod}},
{"updatable", {0, 0, &ServiceParser::ParseUpdatable}},
{"user", {1, 1, &ServiceParser::ParseUser}},
diff --git a/init/service_parser.h b/init/service_parser.h
index f063102..b1281f5 100644
--- a/init/service_parser.h
+++ b/init/service_parser.h
@@ -75,6 +75,7 @@
Result<void> ParseShutdown(std::vector<std::string>&& args);
Result<void> ParseSigstop(std::vector<std::string>&& args);
Result<void> ParseSocket(std::vector<std::string>&& args);
+ Result<void> ParseStdioToKmsg(std::vector<std::string>&& args);
Result<void> ParseTimeoutPeriod(std::vector<std::string>&& args);
Result<void> ParseFile(std::vector<std::string>&& args);
Result<void> ParseUser(std::vector<std::string>&& args);
diff --git a/init/service_utils.cpp b/init/service_utils.cpp
index 35f2acf..93cffd8 100644
--- a/init/service_utils.cpp
+++ b/init/service_utils.cpp
@@ -16,10 +16,12 @@
#include "service_utils.h"
+#include <fcntl.h>
#include <grp.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/wait.h>
+#include <unistd.h>
#include <android-base/file.h>
#include <android-base/logging.h>
@@ -121,11 +123,15 @@
return {};
}
-void ZapStdio() {
+void SetupStdio(bool stdio_to_kmsg) {
auto fd = unique_fd{open("/dev/null", O_RDWR | O_CLOEXEC)};
- dup2(fd, 0);
- dup2(fd, 1);
- dup2(fd, 2);
+ dup2(fd, STDIN_FILENO);
+ if (stdio_to_kmsg) {
+ fd.reset(open("/dev/kmsg_debug", O_WRONLY | O_CLOEXEC));
+ if (fd == -1) fd.reset(open("/dev/null", O_WRONLY | O_CLOEXEC));
+ }
+ dup2(fd, STDOUT_FILENO);
+ dup2(fd, STDERR_FILENO);
}
void OpenConsole(const std::string& console) {
@@ -238,7 +244,7 @@
if (setpgid(0, getpid()) == -1) {
return ErrnoError() << "setpgid failed";
}
- ZapStdio();
+ SetupStdio(attr.stdio_to_kmsg);
}
for (const auto& rlimit : attr.rlimits) {
diff --git a/init/service_utils.h b/init/service_utils.h
index d2e69d9..3f1071e 100644
--- a/init/service_utils.h
+++ b/init/service_utils.h
@@ -77,6 +77,7 @@
gid_t gid;
std::vector<gid_t> supp_gids;
int priority;
+ bool stdio_to_kmsg;
};
Result<void> SetProcessAttributes(const ProcessAttributes& attr);