uml "exec" writes stdout/stderr back to mconsole

guest->exec() accepts a callback for output
sligtly refactored mconsole.c

src/dumm/guest.c

@@ -328,9 +328,10 @@ static bool load_template(private_guest_t *this, char *path)
 /**
  * Implementation of gues_t.exec
  */
-static int exec(private_guest_t *this, char *cmd, ...)
+static int exec(private_guest_t *this, void(*cb)(void*,char*), void *data,
+				char *cmd, ...)
 {
-	char buf[512];
+	char buf[1024];
 	size_t len;
 	va_list args;
 
@@ -342,10 +343,10 @@ static int exec(private_guest_t *this, char *cmd, ...)
 	
 		if (len > 0 && len < sizeof(buf))
 		{
-			return this->mconsole->exec(this->mconsole, buf);
+			return this->mconsole->exec(this->mconsole, cb, data, buf);
 		}
 	}
-	return FALSE;
+	return -1;
 }
 
 /**
@@ -472,7 +473,7 @@ static private_guest_t *guest_create_generic(char *parent, char *name,
 	this->public.start = (void*)start;
 	this->public.stop = (void*)stop;
 	this->public.load_template = (bool(*)(guest_t*, char *path))load_template;
-	this->public.exec = (bool(*)(guest_t*, char *cmd, ...))exec;
+	this->public.exec = (int(*)(guest_t*, void(*cb)(void*,char*,size_t), void *data, char *cmd, ...))exec;
 	this->public.sigchild = (void(*)(guest_t*))sigchild;
 	this->public.destroy = (void*)destroy;
 		

src/dumm/guest.h

@@ -144,11 +144,14 @@ struct guest_t {
 	/**
 	 * Execute a command in the guest.
 	 *
+	 * @param cb		callback to call for each read block
+	 * @param data		data to pass to callback
 	 * @param cmd		command to execute
 	 * @param ...		printf style argument list for cmd
-	 * @return			TRUE if command executed
+	 * @return			return value
 	 */
-	bool (*exec)(guest_t *this, char *cmd, ...);
+	int (*exec)(guest_t *this, void(*cb)(void*,char*,size_t), void *data,
+				char *cmd, ...);
 	
 	/**
 	 * @brief Called whenever a SIGCHILD for the guests PID is received.

src/dumm/iface.c

@@ -105,8 +105,8 @@ static char* get_hostif(private_iface_t *this)
  */
 static bool add_address(private_iface_t *this, host_t *addr)
 {
-	if (this->guest->exec(this->guest, "ip addr add %H dev %s",
+	if (this->guest->exec(this->guest, NULL, NULL, "ip addr add %H dev %s",
-						  addr, this->guestif))
+						  addr, this->guestif) == 0)
 	{
 		this->addresses->insert_last(this->addresses, addr);
 		return TRUE;
@@ -137,8 +137,8 @@ static bool delete_address(private_iface_t *this, host_t *addr)
 	{
 		if (current->ip_equals(current, addr))
 		{
-			if (this->guest->exec(this->guest, "ip addr del %H dev %s",
+			if (this->guest->exec(this->guest, NULL, NULL,
-								  current, this->guestif))
+						"ip addr del %H dev %s", current, this->guestif) == 0)
 			{
 				this->addresses->remove_at(this->addresses, enumerator);
 				success = TRUE;
@@ -157,11 +157,13 @@ static void set_bridge(private_iface_t *this, bridge_t *bridge)
 {
 	if (this->bridge == NULL && bridge)
 	{
-		this->guest->exec(this->guest, "ip link set %s up", this->guestif);
+		this->guest->exec(this->guest, NULL, NULL,
+						  "ip link set %s up", this->guestif);
 	}
 	else if (this->bridge && bridge == NULL)
 	{
-		this->guest->exec(this->guest, "ip link set %s down", this->guestif);
+		this->guest->exec(this->guest, NULL, NULL,
+						  "ip link set %s down", this->guestif);
 	}
 	this->bridge = bridge;
 }

src/dumm/irdumm.c

@@ -123,7 +123,6 @@ static VALUE guest_each(int argc, VALUE *argv, VALUE class)
 
 static VALUE guest_new(VALUE class, VALUE name, VALUE kernel,
 					   VALUE master, VALUE mem)
-
 {
 	guest_t *guest;
 	
@@ -170,12 +169,17 @@ static VALUE guest_stop(VALUE self)
 	return self;
 }
 
+static void cb(void *data, char *buf, size_t len)
+{
+	printf("%.*s", len, buf);
+}
+
 static VALUE guest_exec(VALUE self, VALUE cmd)
 {
 	guest_t *guest;
 	
 	Data_Get_Struct(self, guest_t, guest);
-	if (!guest->exec(guest, StringValuePtr(cmd)))
+	if (guest->exec(guest, cb, NULL, "%s", StringValuePtr(cmd)) != 0)
 	{
 		rb_raise(rb_eRuntimeError, "executing command failed");
 	}

src/dumm/mconsole.c

@@ -88,20 +88,20 @@ struct mconsole_notify {
 /**
  * send a request to UML using mconsole
  */
-static int request(private_mconsole_t *this, char *command,
+static int request(private_mconsole_t *this, void(*cb)(void*,char*,size_t),
-				   char buf[], size_t *size)
+				   void *data, char *command, ...)
 {
 	mconsole_request request;
 	mconsole_reply reply;
-	int len, total = 0, flags = 0;
+	int len, flags = 0;
+	va_list args;
 	
 	memset(&request, 0, sizeof(request));
 	request.magic = MCONSOLE_MAGIC;
 	request.version = MCONSOLE_VERSION;
-	request.len = min(strlen(command), sizeof(reply.data) - 1);
+	va_start(args, command);
-	strncpy(request.data, command, request.len);
+	request.len = vsnprintf(request.data, sizeof(request.data), command, args);
-	*buf = '\0';
+	va_end(args);
-	(*size)--;
 	
 	if (this->idle)
 	{
@@ -120,7 +120,7 @@ static int request(private_mconsole_t *this, char *command,
 	
 	if (len < 0)
 	{
-		snprintf(buf, *size, "sending mconsole command to UML failed: %m");
+		DBG1("sending mconsole command to UML failed: %m");
 		return -1;
 	}
 	do 
@@ -136,44 +136,50 @@ static int request(private_mconsole_t *this, char *command,
 		}
 		if (len < 0)
 		{
-			snprintf(buf, *size, "receiving from mconsole failed: %m");
+			DBG1("receiving from mconsole failed: %m");
 			return -1;
 		}
 		if (len > 0)
 		{
-			strncat(buf, reply.data, min(reply.len, *size - total));
+			if (cb)
-			total += reply.len;
+			{
+				cb(data, reply.data, reply.len);
+			}
+			else if (reply.err)
+			{
+				DBG1("received mconsole error %d: %*.s",
+					 reply.err, reply.len, reply.data);
+				break;
+			}
 		}
 	}
 	while (reply.more);
 	
-	*size = total;
 	return reply.err;
 }
 
+/**
+ * ignore error message
+ */
+static void ignore(void *data, char *buf, size_t len)
+{
+}
+
 /**
  * Implementation of mconsole_t.add_iface.
  */
 static bool add_iface(private_mconsole_t *this, char *guest, char *host)
 {
-	char in[128], out[128];
+	int tries = 0;
-	int len, tries = 0;
 	
-	len = snprintf(in, sizeof(in), "config %s=tuntap,%s", guest, host);
+	while (tries++ < 5)
-	if (len < 0 || len >= sizeof(in))
 	{
-		return FALSE;
+		if (request(this, ignore, NULL, "config %s=tuntap,%s", guest, host) == 0)
-	}
-	while (tries++ < 10)
-	{
-		len = sizeof(in);
-		if (request(this, in, out, &len) == 0)
 		{
 			return TRUE;
 		}
-		usleep(10000 * tries);
+		usleep(10000 * tries * tries);
 	}
-	DBG1("adding interface failed: %.*s", len, out);
 	return FALSE;
 }
 
@@ -182,15 +188,7 @@ static bool add_iface(private_mconsole_t *this, char *guest, char *host)
  */
 static bool del_iface(private_mconsole_t *this, char *guest)
 {	
-	char buf[128];
+	if (request(this, NULL, NULL, "remove %s", guest) != 0)
-	int len;
-	
-	len = snprintf(buf, sizeof(buf), "remove %s", guest);
-	if (len < 0 || len >= sizeof(buf))
-	{
-		return FALSE;
-	}
-	if (request(this, buf, buf, &len) != 0)
 	{
 		return FALSE;
 	}
@@ -200,22 +198,14 @@ static bool del_iface(private_mconsole_t *this, char *guest)
 /**
  * Implementation of mconsole_t.exec
  */
-static bool exec(private_mconsole_t *this, char *cmd)
+static int exec(private_mconsole_t *this, void(*cb)(void*,char*,size_t),
+				void *data, char *cmd)
 {
-	char buf[512];
+	if (request(this, cb, data, "exec %s", cmd) != 0)
-	int len;
-	
-	len = snprintf(buf, sizeof(buf), "exec %s", cmd);
-	if (len < 0 || len >= sizeof(buf))
 	{
 		return -1;
 	}
-	if (request(this, buf, buf, &len) != 0)
+	return 0;
-	{
-		DBG1("exec failed: %.*s", len, buf);
-		return FALSE;
-	}
-	return TRUE;
 }
 
 /**
@@ -223,20 +213,18 @@ static bool exec(private_mconsole_t *this, char *cmd)
  */
 static bool wait_bootup(private_mconsole_t *this)
 {
-	char buf[128];
+	int res;
-	int len, res;
 	
 	while (TRUE)
 	{
-		len = sizeof(buf);
+		res = request(this, ignore, NULL, "config eth9=mcast");
-		res = request(this, "config eth9=mcast", buf, &len);
 		if (res < 0)
 		{
 			return FALSE;
 		}
 		if (res == 0)
 		{
-			while (request(this, "remove eth9", buf, &len) != 0)
+			while (request(this, ignore, NULL, "remove eth9") != 0)
 			{
 				usleep(50000);
 			}
@@ -359,7 +347,7 @@ mconsole_t *mconsole_create(char *notify, void(*idle)(void))
 	
 	this->public.add_iface = (bool(*)(mconsole_t*, char *guest, char *host))add_iface;
 	this->public.del_iface = (bool(*)(mconsole_t*, char *guest))del_iface;
-	this->public.exec = (bool(*)(mconsole_t*, char *cmd))exec;
+	this->public.exec = (int(*)(mconsole_t*,  void(*cb)(void*,char*,size_t), void *data, char *cmd))exec;
 	this->public.destroy = (void*)destroy;
 	
 	this->idle = idle;

src/dumm/mconsole.h

@@ -44,8 +44,14 @@ struct mconsole_t {
 	
 	/**
 	 * Execute a command in the UML host.
+	 *
+	 * @param cb			callback function to invoke for each line
+	 * @param data			data to pass to callback
+	 * @param cmd			command to invoke
+	 * @return				return value of command
 	 */
-	bool (*exec)(mconsole_t *this, char *cmd);
+	int (*exec)(mconsole_t *this, void(*cb)(void*,char*,size_t), void *data,
+				char *cmd);
 	
 	/**
 	 * @brief Destroy the mconsole instance

src/dumm/patches/mconsole-exec-2.6.26.patch

@@ -1,5 +1,5 @@
---- a/arch/um/drivers/mconsole_kern.c	2008-04-17 04:49:44.000000000 +0200
+--- linux-2.6.26rc5-orig/arch/um/drivers/mconsole_kern.c	2008-04-17 04:49:44.000000000 +0200
-+++ b/arch/um/drivers/mconsole_kern.c	2008-07-07 13:55:48.000000000 +0200
++++ uml-2.6.26rc5/arch/um/drivers/mconsole_kern.c	2008-07-08 16:00:07.000000000 +0200
 @@ -4,6 +4,7 @@
   * Licensed under the GPL
   */
@@ -8,41 +8,61 @@
  #include <linux/console.h>
  #include <linux/ctype.h>
  #include <linux/interrupt.h>
-@@ -199,6 +200,24 @@
+@@ -18,6 +19,7 @@
+ #include <linux/utsname.h>
+ #include <linux/workqueue.h>
+ #include <linux/mutex.h>
++#include <linux/file.h>
+ #include <asm/uaccess.h>
+ 
+ #include "init.h"
+@@ -199,6 +201,36 @@
  }
  #endif
  
 +void mconsole_exec(struct mc_request *req)
 +{
-+	int res;
++	int res, len;
++	struct file *out;
++	char buf[MCONSOLE_MAX_DATA];
 +
 +	char *envp[] = { "HOME=/", "TERM=linux", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL };
 +	char *argv[] = { "/bin/sh", "-c", req->request.data + strlen("exec "), NULL };
-+	res = call_usermodehelper("/bin/sh", argv, envp, 0);
++	res = call_usermodehelper_pipe("/bin/sh", argv, envp, NULL, &out);
 +	
 +	if (res < 0) {
-+	char buf[60];
++		mconsole_reply(req, "call_usermodehelper_pipe failed", 1, 0);
-+		snprintf(buf, 60, "call_usermodehelper failed in mconsole_exec with error code: %d", -res);
-+		mconsole_reply(req, buf, 1, 0);
 +		return;
 +	}
 +	
-+	mconsole_reply(req, "The command has been started successfully.", 0, 0);
++	for (;;) {
++		len = out->f_op->read(out, buf, sizeof(buf), 0);
++		if (len < 0) {
++			mconsole_reply(req, "reading output failed", 1, 0);
++			break;
++		}
++		if (len == 0) {
++			mconsole_reply_len(req, buf, len, 0, 0);
++			break;
++		}
++		mconsole_reply_len(req, buf, len, 0, 1);
++	}
++	fput(out);
 +}
 +
  void mconsole_proc(struct mc_request *req)
  {
  	char path[64];
-@@ -270,6 +289,7 @@
+@@ -270,6 +302,7 @@
      stop - pause the UML; it will do nothing until it receives a 'go' \n\
      go - continue the UML after a 'stop' \n\
      log <string> - make UML enter <string> into the kernel log\n\
-+    exec <string> - pass <string> to /bin/sh -c in guest\n\
++    exec <string> - pass <string> to /bin/sh -c synchronously\n\
      proc <file> - returns the contents of the UML's /proc/<file>\n\
      stack <pid> - returns the stack of the specified pid\n\
  "
---- a/arch/um/drivers/mconsole_user.c	2008-05-21 18:34:47.000000000 +0200
+--- linux-2.6.26rc5-orig/arch/um/drivers/mconsole_user.c	2008-05-21 18:34:47.000000000 +0200
-+++ b/arch/um/drivers/mconsole_user.c	2008-07-07 13:47:13.000000000 +0200
++++ uml-2.6.26rc5/arch/um/drivers/mconsole_user.c	2008-07-07 13:47:13.000000000 +0200
 @@ -32,6 +32,7 @@
  	{ "stop", mconsole_stop, MCONSOLE_PROC },
  	{ "go", mconsole_go, MCONSOLE_INTR },
@@ -51,8 +71,8 @@
  	{ "proc", mconsole_proc, MCONSOLE_PROC },
  	{ "stack", mconsole_stack, MCONSOLE_INTR },
  };
---- a/arch/um/include/mconsole.h	2008-04-17 04:49:44.000000000 +0200
+--- linux-2.6.26rc5-orig/arch/um/include/mconsole.h	2008-04-17 04:49:44.000000000 +0200
-+++ b/arch/um/include/mconsole.h	2008-07-07 13:46:56.000000000 +0200
++++ uml-2.6.26rc5/arch/um/include/mconsole.h	2008-07-07 13:46:56.000000000 +0200
 @@ -85,6 +85,7 @@
  extern void mconsole_stop(struct mc_request *req);
  extern void mconsole_go(struct mc_request *req);
@@ -61,3 +81,123 @@
  extern void mconsole_proc(struct mc_request *req);
  extern void mconsole_stack(struct mc_request *req);
  
+--- linux-2.6.26rc5-orig/kernel/kmod.c	2008-05-21 18:34:56.000000000 +0200
++++ uml-2.6.26rc5/kernel/kmod.c	2008-07-08 13:50:37.000000000 +0200
+@@ -125,6 +125,7 @@
+ 	enum umh_wait wait;
+ 	int retval;
+ 	struct file *stdin;
++	struct file *stdout;
+ 	void (*cleanup)(char **argv, char **envp);
+ };
+ 
+@@ -160,8 +161,26 @@
+ 		FD_SET(0, fdt->open_fds);
+ 		FD_CLR(0, fdt->close_on_exec);
+ 		spin_unlock(&f->file_lock);
+-
+-		/* and disallow core files too */
++	}
++	if (sub_info->stdout) {
++		struct files_struct *f = current->files;
++		struct fdtable *fdt;
++		
++		sys_close(1);
++		sys_close(2);
++		get_file(sub_info->stdout);
++		fd_install(1, sub_info->stdout);
++		fd_install(2, sub_info->stdout);
++		spin_lock(&f->file_lock);
++		fdt = files_fdtable(f);
++		FD_SET(1, fdt->open_fds);
++		FD_CLR(1, fdt->close_on_exec);
++		FD_SET(2, fdt->open_fds);
++		FD_CLR(2, fdt->close_on_exec);
++		spin_unlock(&f->file_lock);
++	}
++	if (sub_info->stdin || sub_info->stdout) {
++		/* disallow core files */
+ 		current->signal->rlim[RLIMIT_CORE] = (struct rlimit){0, 0};
+ 	}
+ 
+@@ -433,6 +452,29 @@
+ }
+ EXPORT_SYMBOL(call_usermodehelper_stdinpipe);
+ 
++int call_usermodehelper_stdoutpipe(struct subprocess_info *sub_info,
++				  struct file **filp)
++{
++	struct file *f;
++
++	f = create_write_pipe();
++	if (IS_ERR(f))
++		return PTR_ERR(f);
++	sub_info->stdout = f;
++
++	f = create_read_pipe(f);
++	if (IS_ERR(f)) {
++		free_write_pipe(sub_info->stdout);
++		sub_info->stdout = NULL;
++		return PTR_ERR(f);
++	}
++	*filp = f;
++
++	return 0;
++}
++EXPORT_SYMBOL(call_usermodehelper_stdoutpipe);
++
++
+ /**
+  * call_usermodehelper_exec - start a usermode application
+  * @sub_info: information about the subprocessa
+@@ -489,7 +531,7 @@
+  * lower-level call_usermodehelper_* functions.
+  */
+ int call_usermodehelper_pipe(char *path, char **argv, char **envp,
+-			     struct file **filp)
++			     struct file **in, struct file **out)
+ {
+ 	struct subprocess_info *sub_info;
+ 	int ret;
+@@ -498,9 +540,17 @@
+ 	if (sub_info == NULL)
+ 		return -ENOMEM;
+ 
+-	ret = call_usermodehelper_stdinpipe(sub_info, filp);
+-	if (ret < 0)
+-		goto out;
++	if (in) {
++		ret = call_usermodehelper_stdinpipe(sub_info, in);
++		if (ret < 0)
++			goto out;
++	}
++
++	if (out) {
++		ret = call_usermodehelper_stdoutpipe(sub_info, out);
++		if (ret < 0)
++			goto out;
++	}
+ 
+ 	return call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
+ 
+--- linux-2.6.26rc5-orig/include/linux/kmod.h	2008-04-17 04:49:44.000000000 +0200
++++ uml-2.6.26rc5/include/linux/kmod.h	2008-07-08 10:29:29.000000000 +0200
+@@ -93,6 +93,6 @@
+ 
+ struct file;
+ extern int call_usermodehelper_pipe(char *path, char *argv[], char *envp[],
+-				    struct file **filp);
++				    struct file **in, struct file **out);
+ 
+ #endif /* __LINUX_KMOD_H__ */
+--- linux-2.6.26rc5-orig/fs/exec.c	2008-06-05 14:00:42.000000000 +0200
++++ uml-2.6.26rc5/fs/exec.c	2008-07-08 10:28:33.000000000 +0200
+@@ -1737,7 +1737,7 @@
+ 
+ 		/* SIGPIPE can happen, but it's just never processed */
+  		if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
+-				&file)) {
++				&file, NULL)) {
+  			printk(KERN_INFO "Core dump to %s pipe failed\n",
+ 			       corename);
+  			goto fail_unlock;