3 files changed, 571 insertions, 235 deletions

diff --git a/arch/um/os-Linux/Makefile b/arch/um/os-Linux/Makefile
index b83ac8e21c35..11e30b13e318 100644
--- a/arch/um/os-Linux/Makefile
+++ b/arch/um/os-Linux/Makefile
@@ -4,11 +4,11 @@
 #
 
 obj-y = aio.o elf_aux.o file.o helper.o main.o mem.o process.o signal.o \
-	start_up.o time.o tt.o tty.o uaccess.o user_syms.o drivers/ \
+	start_up.o time.o tt.o tty.o uaccess.o umid.o user_syms.o drivers/ \
 	sys-$(SUBARCH)/
 
 USER_OBJS := aio.o elf_aux.o file.o helper.o main.o mem.o process.o signal.o \
-	start_up.o time.o tt.o tty.o uaccess.o
+	start_up.o time.o tt.o tty.o uaccess.o umid.o
 
 elf_aux.o: $(ARCH_DIR)/kernel-offsets.h
 CFLAGS_elf_aux.o += -I$(objtree)/arch/um
diff --git a/arch/um/os-Linux/aio.c b/arch/um/os-Linux/aio.c
index ffa759addd3c..f897140cc4ae 100644
--- a/arch/um/os-Linux/aio.c
+++ b/arch/um/os-Linux/aio.c
@@ -16,12 +16,12 @@
 #include "mode.h"
 
 struct aio_thread_req {
-        enum aio_type type;
-        int io_fd;
-        unsigned long long offset;
-        char *buf;
-        int len;
-        struct aio_context *aio;
+	enum aio_type type;
+	int io_fd;
+	unsigned long long offset;
+	char *buf;
+	int len;
+	struct aio_context *aio;
 };
 
 static int aio_req_fd_r = -1;
@@ -38,18 +38,18 @@ static int aio_req_fd_w = -1;
 
 static long io_setup(int n, aio_context_t *ctxp)
 {
-        return syscall(__NR_io_setup, n, ctxp);
+	return syscall(__NR_io_setup, n, ctxp);
 }
 
 static long io_submit(aio_context_t ctx, long nr, struct iocb **iocbpp)
 {
-        return syscall(__NR_io_submit, ctx, nr, iocbpp);
+	return syscall(__NR_io_submit, ctx, nr, iocbpp);
 }
 
 static long io_getevents(aio_context_t ctx_id, long min_nr, long nr,
-                         struct io_event *events, struct timespec *timeout)
+			 struct io_event *events, struct timespec *timeout)
 {
-        return syscall(__NR_io_getevents, ctx_id, min_nr, nr, events, timeout);
+	return syscall(__NR_io_getevents, ctx_id, min_nr, nr, events, timeout);
 }
 
 #endif
@@ -66,243 +66,245 @@ static long io_getevents(aio_context_t ctx_id, long min_nr, long nr,
  */
 
 static int do_aio(aio_context_t ctx, enum aio_type type, int fd, char *buf,
-                  int len, unsigned long long offset, struct aio_context *aio)
+		  int len, unsigned long long offset, struct aio_context *aio)
 {
-        struct iocb iocb, *iocbp = &iocb;
-        char c;
-        int err;
-
-        iocb = ((struct iocb) { .aio_data 	= (unsigned long) aio,
-                                .aio_reqprio	= 0,
-                                .aio_fildes	= fd,
-                                .aio_buf	= (unsigned long) buf,
-                                .aio_nbytes	= len,
-                                .aio_offset	= offset,
-                                .aio_reserved1	= 0,
-                                .aio_reserved2	= 0,
-                                .aio_reserved3	= 0 });
-
-        switch(type){
-        case AIO_READ:
-                iocb.aio_lio_opcode = IOCB_CMD_PREAD;
-                err = io_submit(ctx, 1, &iocbp);
-                break;
-        case AIO_WRITE:
-                iocb.aio_lio_opcode = IOCB_CMD_PWRITE;
-                err = io_submit(ctx, 1, &iocbp);
-                break;
-        case AIO_MMAP:
-                iocb.aio_lio_opcode = IOCB_CMD_PREAD;
-                iocb.aio_buf = (unsigned long) &c;
-                iocb.aio_nbytes = sizeof(c);
-                err = io_submit(ctx, 1, &iocbp);
-                break;
-        default:
-                printk("Bogus op in do_aio - %d\n", type);
-                err = -EINVAL;
-                break;
-        }
-
-        if(err > 0)
-                err = 0;
+	struct iocb iocb, *iocbp = &iocb;
+	char c;
+	int err;
+
+	iocb = ((struct iocb) { .aio_data 	= (unsigned long) aio,
+				.aio_reqprio	= 0,
+				.aio_fildes	= fd,
+				.aio_buf	= (unsigned long) buf,
+				.aio_nbytes	= len,
+				.aio_offset	= offset,
+				.aio_reserved1	= 0,
+				.aio_reserved2	= 0,
+				.aio_reserved3	= 0 });
+
+	switch(type){
+	case AIO_READ:
+		iocb.aio_lio_opcode = IOCB_CMD_PREAD;
+		err = io_submit(ctx, 1, &iocbp);
+		break;
+	case AIO_WRITE:
+		iocb.aio_lio_opcode = IOCB_CMD_PWRITE;
+		err = io_submit(ctx, 1, &iocbp);
+		break;
+	case AIO_MMAP:
+		iocb.aio_lio_opcode = IOCB_CMD_PREAD;
+		iocb.aio_buf = (unsigned long) &c;
+		iocb.aio_nbytes = sizeof(c);
+		err = io_submit(ctx, 1, &iocbp);
+		break;
+	default:
+		printk("Bogus op in do_aio - %d\n", type);
+		err = -EINVAL;
+		break;
+	}
+
+	if(err > 0)
+		err = 0;
 	else
 		err = -errno;
 
-        return err;
+	return err;
 }
 
 static aio_context_t ctx = 0;
 
 static int aio_thread(void *arg)
 {
-        struct aio_thread_reply reply;
-        struct io_event event;
-        int err, n, reply_fd;
-
-        signal(SIGWINCH, SIG_IGN);
-
-        while(1){
-                n = io_getevents(ctx, 1, 1, &event, NULL);
-                if(n < 0){
-                        if(errno == EINTR)
-                                continue;
-                        printk("aio_thread - io_getevents failed, "
-                               "errno = %d\n", errno);
-                }
-                else {
-                        reply = ((struct aio_thread_reply)
-				 { .data = (void *) (long) event.data,
-				   .err	= event.res });
+	struct aio_thread_reply reply;
+	struct io_event event;
+	int err, n, reply_fd;
+
+	signal(SIGWINCH, SIG_IGN);
+
+	while(1){
+		n = io_getevents(ctx, 1, 1, &event, NULL);
+		if(n < 0){
+			if(errno == EINTR)
+				continue;
+			printk("aio_thread - io_getevents failed, "
+			       "errno = %d\n", errno);
+		}
+		else {
+			reply = ((struct aio_thread_reply)
+				{ .data = (void *) (long) event.data,
+						.err	= event.res });
 			reply_fd = ((struct aio_context *) reply.data)->reply_fd;
 			err = os_write_file(reply_fd, &reply, sizeof(reply));
-                        if(err != sizeof(reply))
+			if(err != sizeof(reply))
 				printk("aio_thread - write failed, fd = %d, "
-                                       "err = %d\n", aio_req_fd_r, -err);
-                }
-        }
-        return 0;
+				       "err = %d\n", aio_req_fd_r, -err);
+		}
+	}
+	return 0;
 }
 
 #endif
 
 static int do_not_aio(struct aio_thread_req *req)
 {
-        char c;
-        int err;
-
-        switch(req->type){
-        case AIO_READ:
-                err = os_seek_file(req->io_fd, req->offset);
-                if(err)
-                        goto out;
-
-                err = os_read_file(req->io_fd, req->buf, req->len);
-                break;
-        case AIO_WRITE:
-                err = os_seek_file(req->io_fd, req->offset);
-                if(err)
-                        goto out;
-
-                err = os_write_file(req->io_fd, req->buf, req->len);
-                break;
-        case AIO_MMAP:
-                err = os_seek_file(req->io_fd, req->offset);
-                if(err)
-                        goto out;
-
-                err = os_read_file(req->io_fd, &c, sizeof(c));
-                break;
-        default:
-                printk("do_not_aio - bad request type : %d\n", req->type);
-                err = -EINVAL;
-                break;
-        }
-
- out:
-        return err;
+	char c;
+	int err;
+
+	switch(req->type){
+	case AIO_READ:
+		err = os_seek_file(req->io_fd, req->offset);
+		if(err)
+			goto out;
+
+		err = os_read_file(req->io_fd, req->buf, req->len);
+		break;
+	case AIO_WRITE:
+		err = os_seek_file(req->io_fd, req->offset);
+		if(err)
+			goto out;
+
+		err = os_write_file(req->io_fd, req->buf, req->len);
+		break;
+	case AIO_MMAP:
+		err = os_seek_file(req->io_fd, req->offset);
+		if(err)
+			goto out;
+
+		err = os_read_file(req->io_fd, &c, sizeof(c));
+		break;
+	default:
+		printk("do_not_aio - bad request type : %d\n", req->type);
+		err = -EINVAL;
+		break;
+	}
+
+out:
+	return err;
 }
 
 static int not_aio_thread(void *arg)
 {
-        struct aio_thread_req req;
-        struct aio_thread_reply reply;
-        int err;
-
-        signal(SIGWINCH, SIG_IGN);
-        while(1){
-                err = os_read_file(aio_req_fd_r, &req, sizeof(req));
-                if(err != sizeof(req)){
-                        if(err < 0)
-                                printk("not_aio_thread - read failed, "
-                                       "fd = %d, err = %d\n", aio_req_fd_r,
-                                       -err);
-                        else {
-                                printk("not_aio_thread - short read, fd = %d, "
-                                       "length = %d\n", aio_req_fd_r, err);
-                        }
-                        continue;
-                }
-                err = do_not_aio(&req);
-                reply = ((struct aio_thread_reply) { .data 	= req.aio,
-                                                     .err	= err });
-                err = os_write_file(req.aio->reply_fd, &reply, sizeof(reply));
-                if(err != sizeof(reply))
-                        printk("not_aio_thread - write failed, fd = %d, "
-                               "err = %d\n", aio_req_fd_r, -err);
-        }
+	struct aio_thread_req req;
+	struct aio_thread_reply reply;
+	int err;
+
+	signal(SIGWINCH, SIG_IGN);
+	while(1){
+		err = os_read_file(aio_req_fd_r, &req, sizeof(req));
+		if(err != sizeof(req)){
+			if(err < 0)
+				printk("not_aio_thread - read failed, "
+				       "fd = %d, err = %d\n", aio_req_fd_r,
+				       -err);
+			else {
+				printk("not_aio_thread - short read, fd = %d, "
+				       "length = %d\n", aio_req_fd_r, err);
+			}
+			continue;
+		}
+		err = do_not_aio(&req);
+		reply = ((struct aio_thread_reply) { .data 	= req.aio,
+					 .err	= err });
+		err = os_write_file(req.aio->reply_fd, &reply, sizeof(reply));
+		if(err != sizeof(reply))
+			printk("not_aio_thread - write failed, fd = %d, "
+			       "err = %d\n", aio_req_fd_r, -err);
+	}
+
+	return 0;
 }
 
 static int aio_pid = -1;
 
 static int init_aio_24(void)
 {
-        unsigned long stack;
-        int fds[2], err;
-
-        err = os_pipe(fds, 1, 1);
-        if(err)
-                goto out;
-
-        aio_req_fd_w = fds[0];
-        aio_req_fd_r = fds[1];
-        err = run_helper_thread(not_aio_thread, NULL,
-                                CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
-        if(err < 0)
-                goto out_close_pipe;
-
-        aio_pid = err;
-        goto out;
-
- out_close_pipe:
-        os_close_file(fds[0]);
-        os_close_file(fds[1]);
-        aio_req_fd_w = -1;
-        aio_req_fd_r = -1;
- out:
+	unsigned long stack;
+	int fds[2], err;
+
+	err = os_pipe(fds, 1, 1);
+	if(err)
+		goto out;
+
+	aio_req_fd_w = fds[0];
+	aio_req_fd_r = fds[1];
+	err = run_helper_thread(not_aio_thread, NULL,
+				CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
+	if(err < 0)
+		goto out_close_pipe;
+
+	aio_pid = err;
+	goto out;
+
+out_close_pipe:
+	os_close_file(fds[0]);
+	os_close_file(fds[1]);
+	aio_req_fd_w = -1;
+	aio_req_fd_r = -1;
+out:
 #ifndef HAVE_AIO_ABI
 	printk("/usr/include/linux/aio_abi.h not present during build\n");
 #endif
 	printk("2.6 host AIO support not used - falling back to I/O "
 	       "thread\n");
-        return 0;
+	return 0;
 }
 
 #ifdef HAVE_AIO_ABI
 #define DEFAULT_24_AIO 0
 static int init_aio_26(void)
 {
-        unsigned long stack;
-        int err;
+	unsigned long stack;
+	int err;
 
-        if(io_setup(256, &ctx)){
+	if(io_setup(256, &ctx)){
 		err = -errno;
-                printk("aio_thread failed to initialize context, err = %d\n",
-                       errno);
-                return err;
-        }
+		printk("aio_thread failed to initialize context, err = %d\n",
+		       errno);
+		return err;
+	}
 
-        err = run_helper_thread(aio_thread, NULL,
-                                CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
-        if(err < 0)
-                return err;
+	err = run_helper_thread(aio_thread, NULL,
+				CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
+	if(err < 0)
+		return err;
 
-        aio_pid = err;
+	aio_pid = err;
 
 	printk("Using 2.6 host AIO\n");
-        return 0;
+	return 0;
 }
 
 static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
 			 unsigned long long offset, struct aio_context *aio)
 {
-        struct aio_thread_reply reply;
-        int err;
-
-        err = do_aio(ctx, type, io_fd, buf, len, offset, aio);
-        if(err){
-                reply = ((struct aio_thread_reply) { .data = aio,
-                                                     .err  = err });
-                err = os_write_file(aio->reply_fd, &reply, sizeof(reply));
-                if(err != sizeof(reply))
-                        printk("submit_aio_26 - write failed, "
-                               "fd = %d, err = %d\n", aio->reply_fd, -err);
-                else err = 0;
-        }
-
-        return err;
+	struct aio_thread_reply reply;
+	int err;
+
+	err = do_aio(ctx, type, io_fd, buf, len, offset, aio);
+	if(err){
+		reply = ((struct aio_thread_reply) { .data = aio,
+					 .err  = err });
+		err = os_write_file(aio->reply_fd, &reply, sizeof(reply));
+		if(err != sizeof(reply))
+			printk("submit_aio_26 - write failed, "
+			       "fd = %d, err = %d\n", aio->reply_fd, -err);
+		else err = 0;
+	}
+
+	return err;
 }
 
 #else
 #define DEFAULT_24_AIO 1
 static int init_aio_26(void)
 {
-        return -ENOSYS;
+	return -ENOSYS;
 }
 
 static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
 			 unsigned long long offset, struct aio_context *aio)
 {
-        return -ENOSYS;
+	return -ENOSYS;
 }
 #endif
 
@@ -310,8 +312,8 @@ static int aio_24 = DEFAULT_24_AIO;
 
 static int __init set_aio_24(char *name, int *add)
 {
-        aio_24 = 1;
-        return 0;
+	aio_24 = 1;
+	return 0;
 }
 
 __uml_setup("aio=2.4", set_aio_24,
@@ -328,28 +330,27 @@ __uml_setup("aio=2.4", set_aio_24,
 
 static int init_aio(void)
 {
-        int err;
-
-        CHOOSE_MODE(({
-                if(!aio_24){
-                        printk("Disabling 2.6 AIO in tt mode\n");
-                        aio_24 = 1;
-                } }), (void) 0);
-
-        if(!aio_24){
-                err = init_aio_26();
-                if(err && (errno == ENOSYS)){
-                        printk("2.6 AIO not supported on the host - "
-                               "reverting to 2.4 AIO\n");
-                        aio_24 = 1;
-                }
-                else return err;
-        }
-
-        if(aio_24)
-                return init_aio_24();
-
-        return 0;
+	int err;
+
+	CHOOSE_MODE(({ if(!aio_24){
+			    printk("Disabling 2.6 AIO in tt mode\n");
+			    aio_24 = 1;
+		    } }), (void) 0);
+
+	if(!aio_24){
+		err = init_aio_26();
+		if(err && (errno == ENOSYS)){
+			printk("2.6 AIO not supported on the host - "
+			       "reverting to 2.4 AIO\n");
+			aio_24 = 1;
+		}
+		else return err;
+	}
+
+	if(aio_24)
+		return init_aio_24();
+
+	return 0;
 }
 
 /* The reason for the __initcall/__uml_exitcall asymmetry is that init_aio
@@ -362,8 +363,8 @@ __initcall(init_aio);
 
 static void exit_aio(void)
 {
-        if(aio_pid != -1)
-                os_kill_process(aio_pid, 1);
+	if(aio_pid != -1)
+		os_kill_process(aio_pid, 1);
 }
 
 __uml_exitcall(exit_aio);
@@ -371,30 +372,30 @@ __uml_exitcall(exit_aio);
 static int submit_aio_24(enum aio_type type, int io_fd, char *buf, int len,
 			 unsigned long long offset, struct aio_context *aio)
 {
-        struct aio_thread_req req = { .type 		= type,
-                                      .io_fd		= io_fd,
-                                      .offset		= offset,
-                                      .buf		= buf,
-                                      .len		= len,
-                                      .aio		= aio,
-        };
-        int err;
-
-        err = os_write_file(aio_req_fd_w, &req, sizeof(req));
-        if(err == sizeof(req))
-                err = 0;
-
-        return err;
+	struct aio_thread_req req = { .type 		= type,
+				      .io_fd		= io_fd,
+				      .offset		= offset,
+				      .buf		= buf,
+				      .len		= len,
+				      .aio		= aio,
+	};
+	int err;
+
+	err = os_write_file(aio_req_fd_w, &req, sizeof(req));
+	if(err == sizeof(req))
+		err = 0;
+
+	return err;
 }
 
 int submit_aio(enum aio_type type, int io_fd, char *buf, int len,
-               unsigned long long offset, int reply_fd,
-               struct aio_context *aio)
+	       unsigned long long offset, int reply_fd,
+	       struct aio_context *aio)
 {
-        aio->reply_fd = reply_fd;
-        if(aio_24)
-                return submit_aio_24(type, io_fd, buf, len, offset, aio);
-        else {
-                return submit_aio_26(type, io_fd, buf, len, offset, aio);
-        }
+	aio->reply_fd = reply_fd;
+	if(aio_24)
+		return submit_aio_24(type, io_fd, buf, len, offset, aio);
+	else {
+		return submit_aio_26(type, io_fd, buf, len, offset, aio);
+	}
 }
diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c
new file mode 100644
index 000000000000..ecf107ae5ac8
--- /dev/null
+++ b/arch/um/os-Linux/umid.c
@@ -0,0 +1,335 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <signal.h>
+#include <dirent.h>
+#include <sys/fcntl.h>
+#include <sys/stat.h>
+#include <sys/param.h>
+#include "init.h"
+#include "os.h"
+#include "user.h"
+#include "mode.h"
+
+#define UML_DIR "~/.uml/"
+
+#define UMID_LEN 64
+
+/* Changed by set_umid, which is run early in boot */
+char umid[UMID_LEN] = { 0 };
+
+/* Changed by set_uml_dir and make_uml_dir, which are run early in boot */
+static char *uml_dir = UML_DIR;
+
+static int __init make_uml_dir(void)
+{
+	char dir[512] = { '\0' };
+	int len, err;
+
+	if(*uml_dir == '~'){
+		char *home = getenv("HOME");
+
+		err = -ENOENT;
+		if(home == NULL){
+			printk("make_uml_dir : no value in environment for "
+			       "$HOME\n");
+			goto err;
+		}
+		strlcpy(dir, home, sizeof(dir));
+		uml_dir++;
+	}
+	strlcat(dir, uml_dir, sizeof(dir));
+	len = strlen(dir);
+	if (len > 0 && dir[len - 1] != '/')
+		strlcat(dir, "/", sizeof(dir));
+
+	err = -ENOMEM;
+	uml_dir = malloc(strlen(dir) + 1);
+	if (uml_dir == NULL) {
+		printf("make_uml_dir : malloc failed, errno = %d\n", errno);
+		goto err;
+	}
+	strcpy(uml_dir, dir);
+
+	if((mkdir(uml_dir, 0777) < 0) && (errno != EEXIST)){
+	        printf("Failed to mkdir '%s': %s\n", uml_dir, strerror(errno));
+		err = -errno;
+		goto err_free;
+	}
+	return 0;
+
+err_free:
+	free(uml_dir);
+err:
+	uml_dir = NULL;
+	return err;
+}
+
+static int actually_do_remove(char *dir)
+{
+	DIR *directory;
+	struct dirent *ent;
+	int len;
+	char file[256];
+
+	directory = opendir(dir);
+	if(directory == NULL)
+		return -errno;
+
+	while((ent = readdir(directory)) != NULL){
+		if(!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, ".."))
+			continue;
+		len = strlen(dir) + sizeof("/") + strlen(ent->d_name) + 1;
+		if(len > sizeof(file))
+			return -E2BIG;
+
+		sprintf(file, "%s/%s", dir, ent->d_name);
+		if(unlink(file) < 0)
+			return -errno;
+	}
+	if(rmdir(dir) < 0)
+		return -errno;
+
+	return 0;
+}
+
+/* This says that there isn't already a user of the specified directory even if
+ * there are errors during the checking.  This is because if these errors
+ * happen, the directory is unusable by the pre-existing UML, so we might as
+ * well take it over.  This could happen either by
+ * 	the existing UML somehow corrupting its umid directory
+ * 	something other than UML sticking stuff in the directory
+ *	this boot racing with a shutdown of the other UML
+ * In any of these cases, the directory isn't useful for anything else.
+ */
+
+static int not_dead_yet(char *dir)
+{
+	char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
+	char pid[sizeof("nnnnn\0")], *end;
+	int dead, fd, p, n, err;
+
+	n = snprintf(file, sizeof(file), "%s/pid", dir);
+	if(n >= sizeof(file)){
+		printk("not_dead_yet - pid filename too long\n");
+		err = -E2BIG;
+		goto out;
+	}
+
+	dead = 0;
+	fd = open(file, O_RDONLY);
+	if(fd < 0){
+		if(fd != -ENOENT){
+			printk("not_dead_yet : couldn't open pid file '%s', "
+			       "err = %d\n", file, -fd);
+		}
+		goto out;
+	}
+
+	err = 0;
+	n = read(fd, pid, sizeof(pid));
+	if(n <= 0){
+		printk("not_dead_yet : couldn't read pid file '%s', "
+		       "err = %d\n", file, -n);
+		goto out_close;
+	}
+
+	p = strtoul(pid, &end, 0);
+	if(end == pid){
+		printk("not_dead_yet : couldn't parse pid file '%s', "
+		       "errno = %d\n", file, errno);
+		goto out_close;
+	}
+
+	if((kill(p, 0) == 0) || (errno != ESRCH))
+		return 1;
+
+	err = actually_do_remove(dir);
+	if(err)
+		printk("not_dead_yet - actually_do_remove failed with "
+		       "err = %d\n", err);
+
+	return err;
+
+ out_close:
+	close(fd);
+ out:
+	return 0;
+}
+
+static void __init create_pid_file(void)
+{
+	char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
+	char pid[sizeof("nnnnn\0")];
+	int fd, n;
+
+	if(umid_file_name("pid", file, sizeof(file)))
+		return;
+
+	fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644);
+	if(fd < 0){
+		printk("Open of machine pid file \"%s\" failed: %s\n",
+		       file, strerror(-fd));
+		return;
+	}
+
+	snprintf(pid, sizeof(pid), "%d\n", getpid());
+	n = write(fd, pid, strlen(pid));
+	if(n != strlen(pid))
+		printk("Write of pid file failed - err = %d\n", -n);
+
+	close(fd);
+}
+
+int __init set_umid(char *name)
+{
+	if(strlen(name) > UMID_LEN - 1)
+		return -E2BIG;
+
+	strlcpy(umid, name, sizeof(umid));
+
+	return 0;
+}
+
+static int umid_setup = 0;
+
+int __init make_umid(void)
+{
+	int fd, err;
+	char tmp[256];
+
+	if(umid_setup)
+		return 0;
+
+	make_uml_dir();
+
+	if(*umid == '\0'){
+		strlcpy(tmp, uml_dir, sizeof(tmp));
+		strlcat(tmp, "XXXXXX", sizeof(tmp));
+		fd = mkstemp(tmp);
+		if(fd < 0){
+			printk("make_umid - mkstemp(%s) failed: %s\n",
+			       tmp, strerror(errno));
+			err = -errno;
+			goto err;
+		}
+
+		close(fd);
+
+		set_umid(&tmp[strlen(uml_dir)]);
+
+		/* There's a nice tiny little race between this unlink and
+		 * the mkdir below.  It'd be nice if there were a mkstemp
+		 * for directories.
+		 */
+		if(unlink(tmp)){
+			err = -errno;
+			goto err;
+		}
+	}
+
+	snprintf(tmp, sizeof(tmp), "%s%s", uml_dir, umid);
+	err = mkdir(tmp, 0777);
+	if(err < 0){
+		err = -errno;
+		if(errno != EEXIST)
+			goto err;
+
+		if(not_dead_yet(tmp) < 0)
+			goto err;
+
+		err = mkdir(tmp, 0777);
+	}
+	if(err < 0){
+		printk("Failed to create '%s' - err = %d\n", umid, err);
+		goto err_rmdir;
+	}
+
+	umid_setup = 1;
+
+	create_pid_file();
+
+	return 0;
+
+ err_rmdir:
+	rmdir(tmp);
+ err:
+	return err;
+}
+
+static int __init make_umid_init(void)
+{
+	make_umid();
+
+	return 0;
+}
+
+__initcall(make_umid_init);
+
+int __init umid_file_name(char *name, char *buf, int len)
+{
+	int n, err;
+
+	err = make_umid();
+	if(err)
+		return err;
+
+	n = snprintf(buf, len, "%s%s/%s", uml_dir, umid, name);
+	if(n >= len){
+		printk("umid_file_name : buffer too short\n");
+		return -E2BIG;
+	}
+
+	return 0;
+}
+
+char *get_umid(void)
+{
+	return umid;
+}
+
+static int __init set_uml_dir(char *name, int *add)
+{
+	if(*name == '\0'){
+		printf("uml_dir can't be an empty string\n");
+		return 0;
+	}
+
+	if(name[strlen(name) - 1] == '/'){
+		uml_dir = name;
+		return 0;
+	}
+
+	uml_dir = malloc(strlen(name) + 2);
+	if(uml_dir == NULL){
+		printf("Failed to malloc uml_dir - error = %d\n", errno);
+
+		/* Return 0 here because do_initcalls doesn't look at
+		 * the return value.
+		 */
+		return 0;
+	}
+	sprintf(uml_dir, "%s/", name);
+
+	return 0;
+}
+
+__uml_setup("uml_dir=", set_uml_dir,
+"uml_dir=<directory>\n"
+"    The location to place the pid and umid files.\n\n"
+);
+
+static void remove_umid_dir(void)
+{
+	char dir[strlen(uml_dir) + UMID_LEN + 1], err;
+
+	sprintf(dir, "%s%s", uml_dir, umid);
+	err = actually_do_remove(dir);
+	if(err)
+		printf("remove_umid_dir - actually_do_remove failed with "
+		       "err = %d\n", err);
+}
+
+__uml_exitcall(remove_umid_dir);