Author: cem Date: Wed Jan 18 17:55:49 2017 New Revision: 312391 URL: https://svnweb.freebsd.org/changeset/base/312391
Log: ufs/extattr.h: Fix documentation of ea_name termination The ea_name string is not nul-terminated. Correct the documentation. Because the subsequent field is padded to 8 bytes, and the padding is zeroed, the ea_name string will appear to be nul-terminated whenever the length isn't exactly one (mod eight). This was introduced in r167010 (2007). Additionally, mark the length fields as unsigned. This particularly matters for the single byte ea_namelength field, which can represent extended attribute names up to 255 bytes long. No functional change. PR: 216127 Reported by: dewayne at heuristicsystems.com.au Reviewed by: kib@ Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D9206 Modified: head/share/man/man5/fs.5 head/sys/ufs/ufs/extattr.h Modified: head/share/man/man5/fs.5 ============================================================================== --- head/share/man/man5/fs.5 Wed Jan 18 17:55:08 2017 (r312390) +++ head/share/man/man5/fs.5 Wed Jan 18 17:55:49 2017 (r312391) @@ -28,7 +28,7 @@ .\" @(#)fs.5 8.2 (Berkeley) 4/19/94 .\" $FreeBSD$ .\" -.Dd April 23, 2016 +.Dd January 16, 2017 .Dt FS 5 .Os .Sh NAME @@ -388,18 +388,19 @@ For further information, see the include The format of an external attribute is defined by the extattr structure: .Bd -literal struct extattr { - int32_t ea_length; /* length of this attribute */ - int8_t ea_namespace; /* name space of this attribute */ - int8_t ea_contentpadlen; /* padding at end of attribute */ - int8_t ea_namelength; /* length of attribute name */ - char ea_name[1]; /* null-terminated attribute name */ + uint32_t ea_length; /* length of this attribute */ + uint8_t ea_namespace; /* name space of this attribute */ + uint8_t ea_contentpadlen; /* bytes of padding at end of attribute */ + uint8_t ea_namelength; /* length of attribute name */ + char ea_name[1]; /* attribute name (NOT nul-terminated) */ + /* padding, if any, to align attribute content to 8 byte boundary */ /* extended attribute content follows */ }; .Ed .Pp Several macros are defined to manipulate these structures. Each macro takes a pointer to an extattr structure. -.Bl -tag -width ".Dv EXTATTR_SET_LENGTHS(eap, size)" +.Bl -tag -width ".Dv EXTATTR_CONTENT_SIZE(eap)" .It Dv EXTATTR_NEXT(eap) Returns a pointer to the next extended attribute following .Fa eap . @@ -409,35 +410,19 @@ Returns a pointer to the extended attrib .It Dv EXTATTR_CONTENT_SIZE(eap) Returns the size of the extended attribute content referenced by .Fa eap . -.It Dv EXTATTR_SET_LENGTHS(eap, size) -Called with the size of the attribute content after initializing -the attribute name to calculate and set the -.Fa ea_length , -.Fa ea_namelength , -and -.Fa ea_contentpadlen -fields of the extended attribute structure. .El .Pp The following code identifies an ACL: .Bd -literal if (eap->ea_namespace == EXTATTR_NAMESPACE_SYSTEM && - !strcmp(eap->ea_name, POSIX1E_ACL_ACCESS_EXTATTR_NAME) { + eap->ea_namelength == sizeof(POSIX1E_ACL_ACCESS_EXTATTR_NAME) - 1 && + strncmp(eap->ea_name, POSIX1E_ACL_ACCESS_EXTATTR_NAME, + sizeof(POSIX1E_ACL_ACCESS_EXTATTR_NAME) - 1) == 0) { aclp = EXTATTR_CONTENT(eap); acllen = EXTATTR_CONTENT_SIZE(eap); ... } .Ed -.Pp -The following code creates an extended attribute -containing a copy of a structure -.Fa mygif : -.Bd -literal - eap->ea_namespace = EXTATTR_NAMESPACE_USER; - strcpy(eap->ea_name, "filepic.gif"); - EXTATTR_SET_LENGTHS(eap, sizeof(struct mygif)); - memcpy(EXTATTR_CONTENT(eap), &mygif, sizeof(struct mygif)); -.Ed .Sh HISTORY A super-block structure named filsys appeared in .At v6 . Modified: head/sys/ufs/ufs/extattr.h ============================================================================== --- head/sys/ufs/ufs/extattr.h Wed Jan 18 17:55:08 2017 (r312390) +++ head/sys/ufs/ufs/extattr.h Wed Jan 18 17:55:49 2017 (r312391) @@ -73,11 +73,12 @@ struct ufs_extattr_header { * This structure defines the required fields of an extended-attribute header. */ struct extattr { - int32_t ea_length; /* length of this attribute */ - int8_t ea_namespace; /* name space of this attribute */ - int8_t ea_contentpadlen; /* bytes of padding at end of attribute */ - int8_t ea_namelength; /* length of attribute name */ - char ea_name[1]; /* null-terminated attribute name */ + uint32_t ea_length; /* length of this attribute */ + uint8_t ea_namespace; /* name space of this attribute */ + uint8_t ea_contentpadlen; /* bytes of padding at end of attribute */ + uint8_t ea_namelength; /* length of attribute name */ + char ea_name[1]; /* attribute name (NOT nul-terminated) */ + /* padding, if any, to align attribute content to 8 byte boundary */ /* extended attribute content follows */ }; @@ -90,9 +91,6 @@ struct extattr { * content referenced by eap. * EXTATTR_CONTENT_SIZE(eap) returns the size of the extended attribute * content referenced by eap. - * EXTATTR_SET_LENGTHS(eap, contentsize) called after initializing the - * attribute name to calculate and set the ea_length, ea_namelength, - * and ea_contentpadlen fields of the extended attribute structure. */ #define EXTATTR_NEXT(eap) \ ((struct extattr *)(((void *)(eap)) + (eap)->ea_length)) @@ -101,15 +99,6 @@ struct extattr { ((eap)->ea_length - EXTATTR_BASE_LENGTH(eap) - (eap)->ea_contentpadlen) #define EXTATTR_BASE_LENGTH(eap) \ ((sizeof(struct extattr) + (eap)->ea_namelength + 7) & ~7) -#define EXTATTR_SET_LENGTHS(eap, contentsize) do { \ - KASSERT(((eap)->ea_name[0] != 0), \ - ("Must initialize name before setting lengths")); \ - (eap)->ea_namelength = strlen((eap)->ea_name); \ - (eap)->ea_contentpadlen = ((contentsize) % 8) ? \ - 8 - ((contentsize) % 8) : 0; \ - (eap)->ea_length = EXTATTR_BASE_LENGTH(eap) + \ - (contentsize) + (eap)->ea_contentpadlen; \ -} while (0) #ifdef _KERNEL @@ -149,13 +138,6 @@ int ufs_deleteextattr(struct vop_deletee int ufs_setextattr(struct vop_setextattr_args *ap); void ufs_extattr_vnode_inactive(struct vnode *vp, struct thread *td); -#else - -/* User-level definition of KASSERT for macros above */ -#define KASSERT(cond, str) do { \ - if (!(cond)) { printf("panic: "); printf(str); printf("\n"); exit(1); }\ -} while (0) - #endif /* !_KERNEL */ #endif /* !_UFS_UFS_EXTATTR_H_ */ _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
