Author: ed Date: Fri Aug 12 07:03:58 2016 New Revision: 303988 URL: https://svnweb.freebsd.org/changeset/base/303988
Log: Reimplement dirname(3) to be thread-safe. Now that we've updated the prototypes of the basename(3) and dirname(3) functions to conform to POSIX, let's go ahead and reimplement dirname(3) in such a way that it's thread-safe, but also guaranteed to succeed. C libraries like glibc, musl and the one that's part of Solaris already follow such an approach. Move the existing implementation to another source file, freebsd11_dirname.c to keep existing users of the API that pass in a constant string happy, using symbol versioning. Put a new version of the function in dirname.c, obtained from CloudABI's C library. This version scans through the pathname string from left to right, normalizing it, while discarding the last pathname component. Reviewed by: emaste, jilles Differential Revision: https://reviews.freebsd.org/D7355 Added: head/lib/libc/gen/dirname_compat.c - copied, changed from r303452, head/lib/libc/gen/dirname.c Modified: head/lib/libc/gen/Makefile.inc head/lib/libc/gen/Symbol.map head/lib/libc/gen/dirname.3 head/lib/libc/gen/dirname.c Modified: head/lib/libc/gen/Makefile.inc ============================================================================== --- head/lib/libc/gen/Makefile.inc Fri Aug 12 06:19:40 2016 (r303987) +++ head/lib/libc/gen/Makefile.inc Fri Aug 12 07:03:58 2016 (r303988) @@ -29,6 +29,7 @@ SRCS+= __getosreldate.c \ devname.c \ dirfd.c \ dirname.c \ + dirname_compat.c \ disklabel.c \ dlfcn.c \ drand48.c \ Modified: head/lib/libc/gen/Symbol.map ============================================================================== --- head/lib/libc/gen/Symbol.map Fri Aug 12 06:19:40 2016 (r303987) +++ head/lib/libc/gen/Symbol.map Fri Aug 12 07:03:58 2016 (r303988) @@ -82,7 +82,6 @@ FBSD_1.0 { daemon; devname; devname_r; - dirname; getdiskbyname; dladdr; dlclose; @@ -418,6 +417,10 @@ FBSD_1.4 { stravis; }; +FBSD_1.5 { + dirname; +}; + FBSDprivate_1.0 { /* needed by thread libraries */ __thr_jtable; Modified: head/lib/libc/gen/dirname.3 ============================================================================== --- head/lib/libc/gen/dirname.3 Fri Aug 12 06:19:40 2016 (r303987) +++ head/lib/libc/gen/dirname.3 Fri Aug 12 07:03:58 2016 (r303988) @@ -16,7 +16,7 @@ .\" .\" $FreeBSD$ .\" -.Dd July 29, 2016 +.Dd August 12, 2016 .Dt DIRNAME 3 .Os .Sh NAME @@ -37,6 +37,7 @@ Any trailing .Sq \&/ characters are not counted as part of the directory name. +.Sh RETURN VALUES If .Fa path is a null pointer, the empty string, or contains no @@ -46,40 +47,24 @@ characters, returns a pointer to the string .Qq \&. , signifying the current directory. +Otherwise, +it returns a pointer to the parent directory of +.Fa path . .Sh IMPLEMENTATION NOTES -The +This implementation of .Fn dirname -function -returns a pointer to internal storage space allocated on the first call -that will be overwritten -by subsequent calls. +uses the buffer provided by the caller to store the resulting parent +directory. +Other vendor implementations may return a pointer to internal storage +space instead. +The advantage of the former approach is that it ensures thread-safety, +while also placing no upper limit on the supported length of the +pathname. .Pp -Other vendor implementations of -.Fn dirname -may store their result in the input buffer, -making it safe to use in multithreaded applications. -Future versions of -.Fx -will follow this approach as well. -.Sh RETURN VALUES -On successful completion, -.Fn dirname -returns a pointer to the parent directory of -.Fa path . -.Pp -If -.Fn dirname -fails, a null pointer is returned and the global variable -.Va errno -is set to indicate the error. -.Sh ERRORS -The following error codes may be set in -.Va errno : -.Bl -tag -width Er -.It Bq Er ENAMETOOLONG -The path component to be returned was larger than -.Dv MAXPATHLEN . -.El +The algorithm used by this implementation also discards redundant +slashes and +.Qq \&. +pathname components from the pathname string. .Sh SEE ALSO .Xr basename 1 , .Xr dirname 1 , @@ -96,5 +81,10 @@ function first appeared in .Ox 2.2 and .Fx 4.2 . +.Pp +In +.Fx 12.0 , +this function was reimplemented to store its result in the provided +input buffer. .Sh AUTHORS -.An "Todd C. Miller" +.An Nuxi, the Netherlands Modified: head/lib/libc/gen/dirname.c ============================================================================== --- head/lib/libc/gen/dirname.c Fri Aug 12 06:19:40 2016 (r303987) +++ head/lib/libc/gen/dirname.c Fri Aug 12 07:03:58 2016 (r303988) @@ -1,77 +1,90 @@ -/* $OpenBSD: dirname.c,v 1.13 2005/08/08 08:05:33 espie Exp $ */ - -/* - * Copyright (c) 1997, 2004 Todd C. Miller <todd.mil...@courtesan.com> +/*- + * Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/ * - * Permission to use, copy, modify, and distribute this software for any - * purpose with or without fee is hereby granted, provided that the above - * copyright notice and this permission notice appear in all copies. + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. * - * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES - * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF - * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR - * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES - * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN - * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF - * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); -#include <errno.h> #include <libgen.h> -#include <stdlib.h> +#include <stdbool.h> #include <string.h> -#include <sys/param.h> char * dirname(char *path) { - static char *dname = NULL; - size_t len; - const char *endp; - - if (dname == NULL) { - dname = (char *)malloc(MAXPATHLEN); - if (dname == NULL) - return(NULL); - } - - /* Empty or NULL string gets treated as "." */ - if (path == NULL || *path == '\0') { - dname[0] = '.'; - dname[1] = '\0'; - return (dname); + const char *in, *prev, *begin, *end; + char *out; + size_t prevlen; + bool skipslash; + + /* + * If path is a null pointer or points to an empty string, + * dirname() shall return a pointer to the string ".". + */ + if (path == NULL || *path == '\0') + return ((char *)"."); + + /* Retain at least one leading slash character. */ + in = out = *path == '/' ? path + 1 : path; + + skipslash = true; + prev = "."; + prevlen = 1; + for (;;) { + /* Extract the next pathname component. */ + while (*in == '/') + ++in; + begin = in; + while (*in != '/' && *in != '\0') + ++in; + end = in; + if (begin == end) + break; + + /* + * Copy over the previous pathname component, except if + * it's dot. There is no point in retaining those. + */ + if (prevlen != 1 || *prev != '.') { + if (!skipslash) + *out++ = '/'; + skipslash = false; + memmove(out, prev, prevlen); + out += prevlen; + } + + /* Preserve the pathname component for the next iteration. */ + prev = begin; + prevlen = end - begin; } - /* Strip any trailing slashes */ - endp = path + strlen(path) - 1; - while (endp > path && *endp == '/') - endp--; - - /* Find the start of the dir */ - while (endp > path && *endp != '/') - endp--; - - /* Either the dir is "/" or there are no slashes */ - if (endp == path) { - dname[0] = *endp == '/' ? '/' : '.'; - dname[1] = '\0'; - return (dname); - } else { - /* Move forward past the separating slashes */ - do { - endp--; - } while (endp > path && *endp == '/'); - } - - len = endp - path + 1; - if (len >= MAXPATHLEN) { - errno = ENAMETOOLONG; - return (NULL); - } - memcpy(dname, path, len); - dname[len] = '\0'; - return (dname); + /* + * If path does not contain a '/', then dirname() shall return a + * pointer to the string ".". + */ + if (out == path) + *out++ = '.'; + *out = '\0'; + return (path); } Copied and modified: head/lib/libc/gen/dirname_compat.c (from r303452, head/lib/libc/gen/dirname.c) ============================================================================== --- head/lib/libc/gen/dirname.c Thu Jul 28 16:54:12 2016 (r303452, copy source) +++ head/lib/libc/gen/dirname_compat.c Fri Aug 12 07:03:58 2016 (r303988) @@ -26,7 +26,7 @@ __FBSDID("$FreeBSD$"); #include <sys/param.h> char * -dirname(char *path) +__freebsd11_dirname(char *path) { static char *dname = NULL; size_t len; @@ -75,3 +75,5 @@ dirname(char *path) dname[len] = '\0'; return (dname); } + +__sym_compat(dirname, __freebsd11_dirname, FBSD_1.0); _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
