1 files changed, 64 insertions, 33 deletions

diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c
index 362db05..48092b9 100644
--- a/arch/um/os-Linux/umid.c
+++ b/arch/um/os-Linux/umid.c
@@ -67,32 +67,53 @@ err:
 	return err;
 }
 
-static int actually_do_remove(char *dir)
+/*
+ * Unlinks the files contained in @dir and then removes @dir.
+ * Doesn't handle directory trees, so it's not like rm -rf, but almost such. We
+ * ignore ENOENT errors for anything (they happen, strangely enough - possibly due
+ * to races between multiple dying UML threads).
+ */
+static int remove_files_and_dir(char *dir)
 {
 	DIR *directory;
 	struct dirent *ent;
 	int len;
 	char file[256];
+	int ret;
 
 	directory = opendir(dir);
-	if(directory == NULL)
-		return -errno;
+	if (directory == NULL) {
+		if (errno != ENOENT)
+			return -errno;
+		else
+			return 0;
+	}
 
-	while((ent = readdir(directory)) != NULL){
-		if(!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, ".."))
+	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;
+		if (len > sizeof(file)) {
+			ret = -E2BIG;
+			goto out;
+		}
 
 		sprintf(file, "%s/%s", dir, ent->d_name);
-		if(unlink(file) < 0)
-			return -errno;
+		if (unlink(file) < 0 && errno != ENOENT) {
+			ret = -errno;
+			goto out;
+		}
 	}
-	if(rmdir(dir) < 0)
-		return -errno;
 
-	return 0;
+	if (rmdir(dir) < 0 && errno != ENOENT) {
+		ret = -errno;
+		goto out;
+	}
+
+	ret = 0;
+out:
+	closedir(directory);
+	return ret;
 }
 
 /* This says that there isn't already a user of the specified directory even if
@@ -103,9 +124,10 @@ static int actually_do_remove(char *dir)
  * 	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.
+ *
+ * Boolean return: 1 if in use, 0 otherwise.
  */
-
-static int not_dead_yet(char *dir)
+static inline int is_umdir_used(char *dir)
 {
 	char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
 	char pid[sizeof("nnnnn\0")], *end;
@@ -113,7 +135,7 @@ static int not_dead_yet(char *dir)
 
 	n = snprintf(file, sizeof(file), "%s/pid", dir);
 	if(n >= sizeof(file)){
-		printk("not_dead_yet - pid filename too long\n");
+		printk("is_umdir_used - pid filename too long\n");
 		err = -E2BIG;
 		goto out;
 	}
@@ -123,7 +145,7 @@ static int not_dead_yet(char *dir)
 	if(fd < 0) {
 		fd = -errno;
 		if(fd != -ENOENT){
-			printk("not_dead_yet : couldn't open pid file '%s', "
+			printk("is_umdir_used : couldn't open pid file '%s', "
 			       "err = %d\n", file, -fd);
 		}
 		goto out;
@@ -132,18 +154,18 @@ static int not_dead_yet(char *dir)
 	err = 0;
 	n = read(fd, pid, sizeof(pid));
 	if(n < 0){
-		printk("not_dead_yet : couldn't read pid file '%s', "
+		printk("is_umdir_used : couldn't read pid file '%s', "
 		       "err = %d\n", file, errno);
 		goto out_close;
 	} else if(n == 0){
-		printk("not_dead_yet : couldn't read pid file '%s', "
+		printk("is_umdir_used : couldn't read pid file '%s', "
 		       "0-byte read\n", file);
 		goto out_close;
 	}
 
 	p = strtoul(pid, &end, 0);
 	if(end == pid){
-		printk("not_dead_yet : couldn't parse pid file '%s', "
+		printk("is_umdir_used : couldn't parse pid file '%s', "
 		       "errno = %d\n", file, errno);
 		goto out_close;
 	}
@@ -153,19 +175,32 @@ static int not_dead_yet(char *dir)
 		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;
 }
 
+/*
+ * Try to remove the directory @dir unless it's in use.
+ * Precondition: @dir exists.
+ * Returns 0 for success, < 0 for failure in removal or if the directory is in
+ * use.
+ */
+static int umdir_take_if_dead(char *dir)
+{
+	int ret;
+	if (is_umdir_used(dir))
+		return -EEXIST;
+
+	ret = remove_files_and_dir(dir);
+	if (ret) {
+		printk("is_umdir_used - remove_files_and_dir failed with "
+		       "err = %d\n", ret);
+	}
+	return ret;
+}
+
 static void __init create_pid_file(void)
 {
 	char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
@@ -244,11 +279,7 @@ int __init make_umid(void)
 		if(err != -EEXIST)
 			goto err;
 
-		/* 1   -> this umid is already in use
-		 * < 0 -> we couldn't remove the umid directory
-		 * In either case, we can't use this umid, so return -EEXIST.
-		 */
-		if(not_dead_yet(tmp) != 0)
+		if (umdir_take_if_dead(tmp) < 0)
 			goto err;
 
 		err = mkdir(tmp, 0777);
@@ -344,9 +375,9 @@ 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);
+	err = remove_files_and_dir(dir);
 	if(err)
-		printf("remove_umid_dir - actually_do_remove failed with "
+		printf("remove_umid_dir - remove_files_and_dir failed with "
 		       "err = %d\n", err);
 }