[PATCH] uml: umid cleanup

This patch cleans up the umid code:

- The only_if_set argument to get_umid is gone.

- get_umid returns an empty string rather than NULL if there is no umid.

- umid_is_random is gone since its users went away.

- Some printfs were turned into printks because the code runs late enough
  that printk is working.

- Error paths were cleaned up.

- Some functions now return an error and let the caller print the error
  message rather than printing it themselves.  This eliminates the practice of
  passing a pointer to printf or printk in, depending on where in the boot
  process we are.

- Major tidying of not_dead_yet - mostly error path cleanup, plus a comment
  explaining why it doesn't react to errors the way you might expect.

- Calls to os_* interfaces that were moved under os are changed back to
  their native libc forms.

- snprintf, strlcpy, and their bounds-checking friends are used more often,
  replacing by-hand bounds checking in some places.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 154 insertions, 111 deletions

diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c
index 77d69a348cf..ecf107ae5ac 100644
--- a/arch/um/os-Linux/umid.c
+++ b/arch/um/os-Linux/umid.c
@@ -5,6 +5,7 @@
 #include <errno.h>
 #include <signal.h>
 #include <dirent.h>
+#include <sys/fcntl.h>
 #include <sys/stat.h>
 #include <sys/param.h>
 #include "init.h"
@@ -25,15 +26,16 @@ static char *uml_dir = UML_DIR;
 static int __init make_uml_dir(void)
 {
 	char dir[512] = { '\0' };
-	int len;
+	int len, err;
 
 	if(*uml_dir == '~'){
 		char *home = getenv("HOME");
 
+		err = -ENOENT;
 		if(home == NULL){
-			printf("make_uml_dir : no value in environment for "
+			printk("make_uml_dir : no value in environment for "
 			       "$HOME\n");
-			exit(1);
+			goto err;
 		}
 		strlcpy(dir, home, sizeof(dir));
 		uml_dir++;
@@ -43,18 +45,26 @@ static int __init make_uml_dir(void)
 	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);
-		exit(1);
+		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));
-		return(-1);
+		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)
@@ -65,75 +75,88 @@ static int actually_do_remove(char *dir)
 	char file[256];
 
 	directory = opendir(dir);
-	if(directory == NULL){
-		printk("actually_do_remove : couldn't open directory '%s', "
-		       "errno = %d\n", dir, errno);
-		return(1);
-	}
+	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)){
-			printk("Not deleting '%s' from '%s' - name too long\n",
-			       ent->d_name, dir);
-			continue;
-		}
+		if(len > sizeof(file))
+			return -E2BIG;
+
 		sprintf(file, "%s/%s", dir, ent->d_name);
-		if(unlink(file) < 0){
-			printk("actually_do_remove : couldn't remove '%s' "
-			       "from '%s', errno = %d\n", ent->d_name, dir,
-			       errno);
-			return(1);
-		}
-	}
-	if(rmdir(dir) < 0){
-		printk("actually_do_remove : couldn't rmdir '%s', "
-		       "errno = %d\n", dir, errno);
-		return(1);
+		if(unlink(file) < 0)
+			return -errno;
 	}
-	return(0);
+	if(rmdir(dir) < 0)
+		return -errno;
+
+	return 0;
 }
 
-extern int tracing_pid;
+/* 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;
+	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;
+	}
 
-	sprintf(file, "%s/pid", dir);
 	dead = 0;
-	fd = os_open_file(file, of_read(OPENFLAGS()), 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);
-			return(1);
 		}
-		dead = 1;
+		goto out;
 	}
-	if(fd > 0){
-		n = os_read_file(fd, pid, sizeof(pid));
-		if(n < 0){
-			printk("not_dead_yet : couldn't read pid file '%s', "
-			       "err = %d\n", file, -n);
-			return(1);
-		}
-		p = strtoul(pid, &end, 0);
-		if(end == pid){
-			printk("not_dead_yet : couldn't parse pid file '%s', "
-			       "errno = %d\n", file, errno);
-			dead = 1;
-		}
-		if(((kill(p, 0) < 0) && (errno == ESRCH)) ||
-		   (p == CHOOSE_MODE(tracing_pid, os_getpid())))
-			dead = 1;
+
+	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(!dead)
-		return(1);
-	return(actually_do_remove(dir));
+
+	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)
@@ -145,26 +168,26 @@ static void __init create_pid_file(void)
 	if(umid_file_name("pid", file, sizeof(file)))
 		return;
 
-	fd = os_open_file(file, of_create(of_excl(of_rdwr(OPENFLAGS()))),
-			  0644);
+	fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644);
 	if(fd < 0){
-		printf("Open of machine pid file \"%s\" failed: %s\n",
+		printk("Open of machine pid file \"%s\" failed: %s\n",
 		       file, strerror(-fd));
 		return;
 	}
 
-	sprintf(pid, "%d\n", os_getpid());
-	n = os_write_file(fd, pid, strlen(pid));
+	snprintf(pid, sizeof(pid), "%d\n", getpid());
+	n = write(fd, pid, strlen(pid));
 	if(n != strlen(pid))
-		printf("Write of pid file failed - err = %d\n", -n);
-	os_close_file(fd);
+		printk("Write of pid file failed - err = %d\n", -n);
+
+	close(fd);
 }
 
-int __init set_umid(char *name, int (*printer)(const char *fmt, ...))
+int __init set_umid(char *name)
 {
 	if(strlen(name) > UMID_LEN - 1)
-		(*printer)("Unique machine name is being truncated to %d "
-			   "characters\n", UMID_LEN);
+		return -E2BIG;
+
 	strlcpy(umid, name, sizeof(umid));
 
 	return 0;
@@ -172,44 +195,56 @@ int __init set_umid(char *name, int (*printer)(const char *fmt, ...))
 
 static int umid_setup = 0;
 
-int __init make_umid(int (*printer)(const char *fmt, ...))
+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));
-		strcat(tmp, "XXXXXX");
+		strlcat(tmp, "XXXXXX", sizeof(tmp));
 		fd = mkstemp(tmp);
 		if(fd < 0){
-			(*printer)("make_umid - mkstemp(%s) failed: %s\n",
-				   tmp,strerror(errno));
-			return(1);
+			printk("make_umid - mkstemp(%s) failed: %s\n",
+			       tmp, strerror(errno));
+			err = -errno;
+			goto err;
 		}
 
-		os_close_file(fd);
+		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.
 		 */
-		unlink(tmp);
-		set_umid(&tmp[strlen(uml_dir)], printer);
+		if(unlink(tmp)){
+			err = -errno;
+			goto err;
+		}
 	}
 
-	sprintf(tmp, "%s%s", uml_dir, umid);
+	snprintf(tmp, sizeof(tmp), "%s%s", uml_dir, umid);
 	err = mkdir(tmp, 0777);
 	if(err < 0){
-		if(errno == EEXIST){
-			if(not_dead_yet(tmp))
-				return -EEXIST;
-			err = mkdir(tmp, 0777);
-		}
+		err = -errno;
+		if(errno != EEXIST)
+			goto err;
+
+		if(not_dead_yet(tmp) < 0)
+			goto err;
+
+		err = mkdir(tmp, 0777);
 	}
 	if(err < 0){
-		(*printer)("Failed to create %s - errno = %d\n", umid, errno);
-		return(-1);
+		printk("Failed to create '%s' - err = %d\n", umid, err);
+		goto err_rmdir;
 	}
 
 	umid_setup = 1;
@@ -217,13 +252,18 @@ int __init make_umid(int (*printer)(const char *fmt, ...))
 	create_pid_file();
 
 	return 0;
+
+ err_rmdir:
+	rmdir(tmp);
+ err:
+	return err;
 }
 
 static int __init make_umid_init(void)
 {
-	make_umid(printk);
+	make_umid();
 
-	return(0);
+	return 0;
 }
 
 __initcall(make_umid_init);
@@ -232,48 +272,48 @@ int __init umid_file_name(char *name, char *buf, int len)
 {
 	int n, err;
 
-	if(!umid_setup){
-		err = make_umid(printk);
-		if(err)
-			return err;
-	}
+	err = make_umid();
+	if(err)
+		return err;
 
-	n = strlen(uml_dir) + strlen(umid) + strlen("/") + strlen(name) + 1;
-	if(n > len){
+	n = snprintf(buf, len, "%s%s/%s", uml_dir, umid, name);
+	if(n >= len){
 		printk("umid_file_name : buffer too short\n");
-		return(-1);
+		return -E2BIG;
 	}
 
-	sprintf(buf, "%s%s/%s", uml_dir, umid, name);
-	return(0);
+	return 0;
 }
 
-extern int umid_is_random;
-
-char *get_umid(int only_if_set)
+char *get_umid(void)
 {
-	if(only_if_set && umid_is_random)
-		return NULL;
 	return umid;
 }
 
 static int __init set_uml_dir(char *name, int *add)
 {
-	if((strlen(name) > 0) && (name[strlen(name) - 1] != '/')){
-		uml_dir = malloc(strlen(name) + 2);
-		if(uml_dir == NULL){
-			printf("Failed to malloc uml_dir - error = %d\n",
-			       errno);
-			uml_dir = name;
-			/* Return 0 here because do_initcalls doesn't look at
-			 * the return value.
-			 */
-			return(0);
-		}
-		sprintf(uml_dir, "%s/", name);
+	if(*name == '\0'){
+		printf("uml_dir can't be an empty string\n");
+		return 0;
 	}
-	else uml_dir = name;
-	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,
@@ -283,10 +323,13 @@ __uml_setup("uml_dir=", set_uml_dir,
 
 static void remove_umid_dir(void)
 {
-	char dir[strlen(uml_dir) + UMID_LEN + 1];
+	char dir[strlen(uml_dir) + UMID_LEN + 1], err;
 
 	sprintf(dir, "%s%s", uml_dir, umid);
-	actually_do_remove(dir);
+	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);