Enable multiple consoles

This CL allows enabling of multiple consoles. The expected format
of "androidboot.console" kernel parameter is a list of available
consoles, as follows:

  androidboot.console=tty0:ttyS0

A service can be mapped to a specific console by providing the
optional argument, IE "tty0", to "console" service attribute as follows:

service fbconsole /system/bin/sh
    class core
    console tty0
    disabled
    user shell
    group shell log readproc
    seclabel u:r:shell:s0

Bug: None
Change-Id: I3f8556425c8651bd121995869700f18b23365d55
Tracked-On: https://jira01.devtools.intel.com/browse/BP-289

5 files changed, 33 insertions, 39 deletions

diff --git a/init/init.cpp b/init/init.cpp
index bac27df88..704597d2d 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -74,8 +74,7 @@ static int property_triggers_enabled = 0;
 
 static char qemu[32];
 
-int have_console;
-std::string console_name = "/dev/console";
+std::vector<std::string> console_names;
 static time_t process_needs_restart;
 
 const char *ENV[32];
@@ -298,38 +297,23 @@ static int keychord_init_action(const std::vector<std::string>& args)
 
 static int console_init_action(const std::vector<std::string>& args)
 {
-    std::string console = property_get("ro.boot.console");
-    if (!console.empty()) {
-        console_name = "/dev/" + console;
-    }
-
-    int fd = open(console_name.c_str(), O_RDWR | O_CLOEXEC);
-    if (fd >= 0)
-        have_console = 1;
-    close(fd);
-
-    fd = open("/dev/tty0", O_WRONLY | O_CLOEXEC);
-    if (fd >= 0) {
-        const char *msg;
-            msg = "\n"
-        "\n"
-        "\n"
-        "\n"
-        "\n"
-        "\n"
-        "\n"  // console is 40 cols x 30 lines
-        "\n"
-        "\n"
-        "\n"
-        "\n"
-        "\n"
-        "\n"
-        "\n"
-        "             A N D R O I D ";
-        write(fd, msg, strlen(msg));
-        close(fd);
+    std::vector<std::string> consoles;
+    std::string c_prop = property_get("ro.boot.console");
+    if (c_prop.empty()) {
+        // Property is missing, so check the system console by default.
+        consoles.emplace_back(DEFAULT_CONSOLE);
+    } else {
+        consoles = android::base::Split(c_prop, ":");
     }
 
+    for (const auto& c : consoles) {
+        std::string console = "/dev/" + c;
+        int fd = open(console.c_str(), O_RDWR | O_CLOEXEC);
+        if (fd != -1) {
+            console_names.emplace_back(c);
+            close(fd);
+        }
+    }
     return 0;
 }
 
diff --git a/init/init.h b/init/init.h
index b6a095b94..c844489ac 100644
--- a/init/init.h
+++ b/init/init.h
@@ -18,16 +18,17 @@
 #define _INIT_INIT_H
 
 #include <string>
+#include <vector>
 
 class Action;
 class Service;
 
 #define COMMAND_RETRY_TIMEOUT 5
+#define DEFAULT_CONSOLE "console"
 
 extern const char *ENV[32];
 extern bool waiting_for_exec;
-extern int have_console;
-extern std::string console_name;
+extern std::vector<std::string> console_names;
 extern struct selabel_handle *sehandle;
 extern struct selabel_handle *sehandle_prop;
 
diff --git a/init/readme.txt b/init/readme.txt
index ef85ccf1f..7d453c674 100644
--- a/init/readme.txt
+++ b/init/readme.txt
@@ -115,6 +115,11 @@ Options
 Options are modifiers to services.  They affect how and when init
 runs the service.
 
+console [<console>]
+  This service needs a console. The optional second parameter chooses a
+  specific console instead of the default "/dev/console". The leading "/dev/"
+  should be omitted, so "/dev/tty0" would be specified as just "console tty0".
+
 critical
   This is a device-critical service. If it exits more than four times in
   four minutes, the device will reboot into recovery mode.
diff --git a/init/service.cpp b/init/service.cpp
index bdecc324f..e7bbf7b20 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -172,6 +172,7 @@ bool Service::HandleClass(const std::vector<std::string>& args, std::string* err
 
 bool Service::HandleConsole(const std::vector<std::string>& args, std::string* err) {
     flags_ |= SVC_CONSOLE;
+    console_ = args.size() > 1 ? args[1] : DEFAULT_CONSOLE;
     return true;
 }
 
@@ -282,7 +283,7 @@ Service::OptionHandlerMap::Map& Service::OptionHandlerMap::map() const {
     constexpr std::size_t kMax = std::numeric_limits<std::size_t>::max();
     static const Map option_handlers = {
         {"class",       {1,     1,    &Service::HandleClass}},
-        {"console",     {0,     0,    &Service::HandleConsole}},
+        {"console",     {0,     1,    &Service::HandleConsole}},
         {"critical",    {0,     0,    &Service::HandleCritical}},
         {"disabled",    {0,     0,    &Service::HandleDisabled}},
         {"group",       {1,     NR_SVC_SUPP_GIDS + 1, &Service::HandleGroup}},
@@ -329,7 +330,7 @@ bool Service::Start(const std::vector<std::string>& dynamic_args) {
     }
 
     bool needs_console = (flags_ & SVC_CONSOLE);
-    if (needs_console && !have_console) {
+    if (needs_console && console_names.empty()) {
         ERROR("service '%s' requires console\n", name_.c_str());
         flags_ |= SVC_DISABLED;
         return false;
@@ -606,10 +607,12 @@ void Service::ZapStdio() const {
 }
 
 void Service::OpenConsole() const {
-    int fd;
-    if ((fd = open(console_name.c_str(), O_RDWR)) < 0) {
-        fd = open("/dev/null", O_RDWR);
+    int fd = -1;
+    if (std::find(console_names.begin(), console_names.end(), console_) != console_names.end()) {
+        std::string c_path = "/dev/" + console_;
+        fd = open(c_path.c_str(), O_RDWR);
     }
+    if (fd == -1) fd = open("/dev/null", O_RDWR);
     ioctl(fd, TIOCSCTTY, 0);
     dup2(fd, 0);
     dup2(fd, 1);
diff --git a/init/service.h b/init/service.h
index 35abde9b7..b003ca0cc 100644
--- a/init/service.h
+++ b/init/service.h
@@ -129,6 +129,7 @@ private:
 
     std::string name_;
     std::string classname_;
+    std::string console_;
 
     unsigned flags_;
     pid_t pid_;