1 files changed, 335 insertions, 0 deletions
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);