--- realpath.c.orig 2003-08-15 19:22:17.000000000 -0700 +++ realpath.c 2004-12-04 14:47:52.000000000 -0800 @@ -35,13 +35,35 @@ #include "namespace.h" #include <sys/param.h> #include <sys/stat.h> +#include <sys/mount.h> #include <errno.h> #include <stdlib.h> #include <string.h> #include <unistd.h> +#include <sys/attr.h> +#include <sys/vnode.h> #include "un-namespace.h" +struct attrs { + u_int32_t len; + attrreference_t name; + dev_t dev; + fsobj_type_t type; + fsobj_id_t id; + char buf[PATH_MAX]; +}; + +static struct attrlist alist = { + ATTR_BIT_MAP_COUNT, + 0, + ATTR_CMN_NAME | ATTR_CMN_DEVID | ATTR_CMN_OBJTYPE | ATTR_CMN_OBJID, + 0, + 0, + 0, + 0, +}; + /* * char *realpath(const char *path, char resolved[PATH_MAX]); * @@ -52,13 +74,25 @@ char * realpath(const char *path, char resolved[PATH_MAX]) { + struct attrs attrs; struct stat sb; char *p, *q, *s; - size_t left_len, resolved_len; + size_t left_len, resolved_len, save_resolved_len; unsigned symlinks; - int serrno, slen; + int serrno, slen, useattrs, islink; char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; + dev_t dev, lastdev; + struct statfs sfs; + static dev_t rootdev; + static int rootdev_inited = 0; + ino_t inode; + if (!rootdev_inited) { + rootdev_inited = 1; + if (stat("/", &sb) < 0) + return (NULL); + rootdev = sb.st_dev; + } serrno = errno; symlinks = 0; if (path[0] == '/') { @@ -80,6 +114,12 @@ errno = ENAMETOOLONG; return (NULL); } + if (resolved_len > 1) { + if (stat(resolved, &sb) < 0) + return (NULL); + lastdev = sb.st_dev; + } else + lastdev = rootdev; /* * Iterate over path components in `left'. @@ -127,6 +167,13 @@ } /* + * Save resolved_len, so that we can later null out + * the the appended next_token, and replace with the + * real name (matters on case-insensitive filesystems). + */ + save_resolved_len = resolved_len; + + /* * Append the next path component and lstat() it. If * lstat() fails we still can return successfully if * there are no more path components left. @@ -136,14 +183,72 @@ errno = ENAMETOOLONG; return (NULL); } - if (lstat(resolved, &sb) != 0) { + if (getattrlist(resolved, &alist, &attrs, sizeof(attrs), FSOPT_NOFOLLOW) == 0) { + useattrs = 1; + islink = (attrs.type == VLNK); + dev = attrs.dev; + inode = attrs.id.fid_objno; + } else if (errno == EOPNOTSUPP || errno == EINVAL) { + if ((useattrs = lstat(resolved, &sb)) == 0) { + islink = S_ISLNK(sb.st_mode); + dev = sb.st_dev; + inode = sb.st_ino; + } + } else + useattrs = -1; + if (useattrs < 0) { if (errno == ENOENT && p == NULL) { errno = serrno; return (resolved); } return (NULL); } - if (S_ISLNK(sb.st_mode)) { + if (dev != lastdev) { + /* + * We have crossed a mountpoint. For volumes like UDF + * the getattrlist name may not match the actual + * mountpoint, so we just copy the mountpoint directly. + * (3703138). However, the mountpoint may not be + * accessible, as when chroot-ed, so check first. + * There may be a file on the chroot-ed volume with + * the same name as the mountpoint, so compare device + * and inode numbers. + */ + lastdev = dev; + if (statfs(resolved, &sfs) == 0 && lstat(sfs.f_mntonname, &sb) == 0 && dev == sb.st_dev && inode == sb.st_ino) { + /* + * However, it's possible that the mountpoint + * path matches, even though it isn't the real + * path in the chroot-ed environment, so check + * that each component of the mountpoint + * is a directory (and not a symlink) + */ + char temp[MNAMELEN]; + char *cp; + int ok = 1; + + strcpy(temp, sfs.f_mntonname); + for(;;) { + if ((cp = strrchr(temp, '/')) == NULL) { + ok = 0; + break; + } + if (cp <= temp) + break; + *cp = 0; + if (lstat(temp, &sb) < 0 || (sb.st_mode & S_IFMT) != S_IFDIR) { + ok = 0; + break; + } + } + if (ok) { + resolved_len = strlcpy(resolved, sfs.f_mntonname, PATH_MAX); + continue; + } + } + /* if we fail, use the other methods. */ + } + if (islink) { if (symlinks++ > MAXSYMLINKS) { errno = ELOOP; return (NULL); @@ -155,6 +260,7 @@ if (symlink[0] == '/') { resolved[1] = 0; resolved_len = 1; + lastdev = rootdev; } else if (resolved_len > 1) { /* Strip the last path component. */ resolved[resolved_len - 1] = '\0'; @@ -184,7 +290,30 @@ } } left_len = strlcpy(left, symlink, sizeof(left)); + } else if (useattrs) { + /* + * attrs already has the real name. + */ + + resolved[save_resolved_len] = '\0'; + resolved_len = strlcat(resolved, (const char *)&attrs.name + attrs.name.attr_dataoffset, PATH_MAX); + if (resolved_len >= PATH_MAX) { + errno = ENAMETOOLONG; + return (NULL); + } } + /* + * For the case of useattrs == 0, we could scan the directory + * and try to match the inode. There are many problems with + * this: (1) the directory may not be readable, (2) for multiple + * hard links, we would find the first, but not necessarily + * the one specified in the path, (3) we can't try to do + * a case-insensitive search to match the right one in (2), + * because the underlying filesystem may do things like + * decompose composed characters. For most cases, doing + * nothing is the right thing when useattrs == 0, so we punt + * for now. + */ } /*