teach find_root_device to deal with /dev/ subdirs

(by "Kirill K. Smirnov" <lich@math.spbu.ru>)

coreutils/ls.c

@@ -504,11 +504,11 @@ static struct dnode **list_dir(const char *path)
 
 		/* are we going to list the file- it may be . or .. or a hidden file */
 		if (entry->d_name[0] == '.') {
-			if ((entry->d_name[1] == 0 || (
-				entry->d_name[1] == '.'
-				&& entry->d_name[2] == 0))
-					&& !(all_fmt & DISP_DOT))
+			if ((!entry->d_name[1] || (entry->d_name[1] == '.' && !entry->d_name[2]))
+			 && !(all_fmt & DISP_DOT)
+			) {
 				continue;
+			}
 			if (!(all_fmt & DISP_HIDDEN))
 				continue;
 		}

coreutils/rm.c

@@ -40,7 +40,7 @@ int rm_main(int argc, char **argv)
 		do {
 			const char *base = bb_get_last_path_component(*argv);
 
-			if ((base[0] == '.') && (!base[1] || ((base[1] == '.') && !base[2]))) {
+			if (DOT_OR_DOTDOT(base)) {
 				bb_error_msg("cannot remove '.' or '..'");
 			} else if (remove_file(*argv, flags) >= 0) {
 				continue;

include/libbb.h

@@ -405,6 +405,7 @@ extern char *xasprintf(const char *format, ...) __attribute__ ((format (printf,
 #define NOT_LONE_DASH(s) ((s)[0] != '-' || (s)[1])
 #define LONE_CHAR(s,c)     ((s)[0] == (c) && !(s)[1])
 #define NOT_LONE_CHAR(s,c) ((s)[0] != (c) || (s)[1])
+#define DOT_OR_DOTDOT(s) ((s)[0] == '.' && (!(s)[1] || ((s)[1] == '.' && !(s)[2])))
 
 /* dmalloc will redefine these to it's own implementation. It is safe
  * to have the prototypes here unconditionally.  */

libbb/concat_subpath_file.c

@@ -17,7 +17,7 @@
 
 char *concat_subpath_file(const char *path, const char *f)
 {
-	if (f && *f == '.' && (!f[1] || (f[1] == '.' && !f[2])))
+	if (f && DOT_OR_DOTDOT(f))
 		return NULL;
 	return concat_path_file(path, f);
 }

libbb/find_root_device.c

@@ -9,26 +9,65 @@
 
 #include "libbb.h"
 
-char *find_block_device(const char *path)
+/* Find block device /dev/XXX which contains specified file
+ * We handle /dev/dir/dir/dir too, at a cost of ~80 more bytes code */
+
+/* Do not reallocate all this stuff on each recursion */
+enum { DEVNAME_MAX = 256 };
+struct arena {
+	struct stat st;
+	dev_t dev;
+	/* Was PATH_MAX, but we recurse _/dev_. We can assume
+	 * people are not crazy enough to have mega-deep tree there */
+	char devpath[DEVNAME_MAX];
+};
+
+static char *find_block_device_in_dir(struct arena *ap)
 {
 	DIR *dir;
 	struct dirent *entry;
-	struct stat st;
-	dev_t dev;
-	char *retpath=NULL;
+	char *retpath = NULL;
+	int len, rem;
 
-	if (stat(path, &st) || !(dir = opendir("/dev")))
+	dir = opendir(ap->devpath);
+	if (!dir)
 		return NULL;
-	dev = (st.st_mode & S_IFMT) == S_IFBLK ? st.st_rdev : st.st_dev;
+
+	len = strlen(ap->devpath);
+	rem = DEVNAME_MAX-2 - len;
+	if (rem <= 0)
+		return NULL;
+	ap->devpath[len++] = '/';
+
 	while ((entry = readdir(dir)) != NULL) {
-		char devpath[PATH_MAX];
-		sprintf(devpath,"/dev/%s", entry->d_name);
-		if (!stat(devpath, &st) && S_ISBLK(st.st_mode) && st.st_rdev == dev) {
-			retpath = xstrdup(devpath);
+		safe_strncpy(ap->devpath + len, entry->d_name, rem);
+		if (stat(ap->devpath, &ap->st) != 0)
+			continue;
+		if (S_ISBLK(ap->st.st_mode) && ap->st.st_rdev == ap->dev) {
+			retpath = xstrdup(ap->devpath);
 			break;
 		}
+		if (S_ISDIR(ap->st.st_mode)) {
+			/* Do not recurse for '.' and '..' */
+			if (DOT_OR_DOTDOT(entry->d_name))
+				continue;
+			retpath = find_block_device_in_dir(ap);
+			if (retpath)
+				break;
+		}
 	}
 	closedir(dir);
 
 	return retpath;
 }
+
+char *find_block_device(const char *path)
+{
+	struct arena a;
+
+	if (stat(path, &a.st) != 0)
+		return NULL;
+	a.dev = S_ISBLK(a.st.st_mode) ? a.st.st_rdev : a.st.st_dev;
+	strcpy(a.devpath, "/dev");
+	return find_block_device_in_dir(&a);
+}

libbb/simplify_path.c

@@ -26,13 +26,16 @@ char *bb_simplify_path(const char *path)
 		if (*p == '/') {
 			if (*s == '/') {	/* skip duplicate (or initial) slash */
 				continue;
-			} else if (*s == '.') {
-				if (s[1] == '/' || s[1] == 0) {	/* remove extra '.' */
+			}
+			if (*s == '.') {
+				if (s[1] == '/' || !s[1]) {	/* remove extra '.' */
 					continue;
-				} else if ((s[1] == '.') && (s[2] == '/' || s[2] == 0)) {
+				}
+				if ((s[1] == '.') && (s[2] == '/' || !s[2])) {
 					++s;
 					if (p > start) {
-						while (*--p != '/');	/* omit previous dir */
+						while (*--p != '/')	/* omit previous dir */
+							continue;
 					}
 					continue;
 				}

miscutils/devfsd.c

@@ -1369,7 +1369,7 @@ static void dir_operation(int type, const char * dir_name, int var, unsigned lon
 	while ( (de = readdir (dp) ) != NULL )
 	{
 
-		if(de->d_name && *de->d_name == '.' && (!de->d_name[1] || (de->d_name[1] == '.' && !de->d_name[2])))
+		if(de->d_name && DOT_OR_DOTDOT(de->d_name))
 			continue;
 		snprintf (path, sizeof (path), "%s/%s", dir_name, de->d_name);
 		debug_msg_logger(LOG_ERR, "%s: %s", __FUNCTION__, path);

networking/httpd.c

@@ -1573,7 +1573,7 @@ static void handleIncoming(void)
 		}
 
 		/* algorithm stolen from libbb bb_simplify_path(),
-			 but don't strdup and reducing trailing slash and protect out root */
+		 * but don't strdup and reducing trailing slash and protect out root */
 		purl = test = url;
 		do {
 			if (*purl == '/') {
@@ -1583,18 +1583,18 @@ static void handleIncoming(void)
 				}
 				if (*test == '.') {
 					/* skip extra '.' */
-					if (test[1] == '/' || test[1] == 0) {
+					if (test[1] == '/' || !test[1]) {
 						continue;
-					} else
+					}
 					/* '..': be careful */
-					if (test[1] == '.' && (test[2] == '/' || test[2] == 0)) {
+					if (test[1] == '.' && (test[2] == '/' || !test[2])) {
 						++test;
 						if (purl == url) {
 							/* protect out root */
 							goto BAD_REQUEST;
 						}
 						while (*--purl != '/') /* omit previous dir */;
-						continue;
+							continue;
 					}
 				}
 			}

shell/ash.c

@@ -2293,7 +2293,8 @@ updatepwd(const char *dir)
 						break;
 				}
 				break;
-			} else if (p[1] == '\0')
+			}
+			if (p[1] == '\0')
 				break;
 			/* fall through */
 		default: