From meem@triplex.East.Sun.COM Wed Nov 1 17:30:25 2006 Received: from sunmail1brm.Central.Sun.COM (sunmail1brm.Central.Sun.COM [129.147.62.17]) by sac.sfbay.sun.com (8.13.6+Sun/8.13.6) with ESMTP id kA21UOj8001195 for ; Wed, 1 Nov 2006 17:30:25 -0800 (PST) Received: from nwk-avmta-2.sfbay.sun.com (nwk-avmta-2.SFBay.Sun.COM [129.149.247.22]) by sunmail1brm.Central.Sun.COM (8.11.7p1+Sun/8.11.7/ENSMAIL,v2.2) with ESMTP id kA21UO718390 for <@sunmail3.sfbay.sun.com:PSARC-EXT@sun.com>; Wed, 1 Nov 2006 18:30:24 -0700 (MST) Received: from pmxchannel-daemon.nwk-avmta-2.sfbay.sun.com by nwk-avmta-2.sfbay.sun.com (Sun Java System Messaging Server 6.2-3.04 (built Jul 15 2005)) id <0J8200C0HXIMCB00@nwk-avmta-2.sfbay.sun.com> for PSARC-EXT@sun.com (ORCPT PSARC-EXT@sun.com); Wed, 01 Nov 2006 17:30:22 -0800 (PST) Received: from triplex.East.Sun.COM ([129.148.174.104]) by nwk-avmta-2.sfbay.sun.com (Sun Java System Messaging Server 6.2-3.04 (built Jul 15 2005)) with ESMTP id <0J82004T8XILZ660@nwk-avmta-2.sfbay.sun.com> for PSARC-EXT@sun.com (ORCPT PSARC-EXT@sun.com); Wed, 01 Nov 2006 17:30:22 -0800 (PST) Received: from triplex.East.Sun.COM (localhost [127.0.0.1]) by triplex.East.Sun.COM (8.13.8+Sun/8.13.8) with ESMTP id kA21UL1i006661; Wed, 01 Nov 2006 20:30:21 -0500 (EST) Received: (from meem@localhost) by triplex.East.Sun.COM (8.13.8+Sun/8.13.8/Submit) id kA21ULs3006658; Wed, 01 Nov 2006 20:30:21 -0500 (EST) Date: Wed, 01 Nov 2006 20:30:20 -0500 From: Peter Memishian Subject: PSARC/2006/617 strnlen() To: PSARC-EXT@sun.com Cc: rlhamil@smart.net Message-id: <17737.18988.986535.344067@triplex.East.Sun.COM> MIME-version: 1.0 X-Mailer: VM 7.17 under 21.4 (patch 18) "Social Property" XEmacs Lucid Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7BIT X-PMX-Version: 5.2.0.264296 Status: RO Content-Length: 4271 I am sponsoring the following case for Richard Hamilton. Patch binding is requested, with a stability classification of "committed". The timer is set for Wednesday, November 8th. *** NOTE: This case has "open" exposure, and will be visible to the *** *** OpenSolaris community. No confidential information, please! *** Overview ======== This case proposes to add the well-known strnlen() function to libc, which determines the length of a fixed-size string: #include size_t strnlen(const char *s, size_t n); Specifically, the strnlen() functions returns the smaller of `n' or the number of bytes in `s', not including the terminating NUL character. The strnlen() function will never examine more than `n' bytes of the string pointed to by `s'. Details ======= The subject of strnlen() came up in a discussion of the libdlpi code review on clearview-discuss@opensolaris.org, where it might have been handy if a function like strnlen() was available. Richard Hamilton pointed out the concept (and function name) were well-defined in other environments, and posted an earlier implementation. Others, both within and outside Sun, provided essential suggestions and assistance. The proposed strnlen() function complies with Linux Standards Base 1.2: http://refspecs.freestandards.org/LSB_1.2.0/gLSB/baselib-strnlen-3.html ... and also with the (identical) version in LSB3.0Preview1. The strnlen() function is also under consideration for addition to POSIX: http://www.opengroup.org/austin/plato/uploads/40/9756/NAPI_overview.txt However, the established #ifdef guards will prevent strnlen() from being exposed via in standards-conforming environments for now. Microsoft also has an interface-compatible implementation of strnlen(): http://msdn2.microsoft.com/en-us/library/z50ty2zh.aspx Microsoft notes that strnlen() does not validate its parameters, i.e. a NULL string argument would cause an "access violation". The same seems true of other implementations, which is consistent with the behavior of similar functions such as strlen(3C). Our proposed version leaves the behavior of passing a NULL pointer unspecified. Platform-optimized implementations are certainly possible (another open-source implementation appears to be restructuring to allow that for strnlen()), but are beyond the scope of this proposal (and may not be desirable anyway from a maintenance perspective). Various open source applications use strnlen(); some will auto-configure to use a system library provided version if available. Such applications will automatically take advantage of strnlen() once it is available. Others can be modified to use it as the need arises. Manpage Changes =============== --- string.3c.old Wed Nov 1 01:42:38 2006 +++ string.3c Wed Nov 1 17:47:08 2006 @@ -5,8 +5,8 @@ NAME string, strcasecmp, strncasecmp, strcat, strncat, strlcat, strchr, strrchr, strcmp, strncmp, strcpy, strncpy, strlcpy, - strcspn, strspn, strdup, strlen, strpbrk, strstr, strtok, - strtok_r - string operations + strcspn, strspn, strdup, strlen, strnlen, strpbrk, strstr, + strtok, strtok_r - string operations SYNOPSIS #include @@ -47,6 +47,8 @@ size_t strlen(const char *s); + size_t strnlen(const char *s, size_t n); + char *strpbrk(const char *s1, const char *s2); char *strstr(const char *s1, const char *s2); @@ -171,10 +173,15 @@ set to ENOMEM to indicate that the storage space available is insufficient. - strlen() + strlen(), strnlen() The strlen() function returns the number of bytes in s, not including the terminating null character. + The strnlen() function returns the smaller of n or the + number of bytes in s, not including the terminating null + character. The strnlen() function never examines more than + n bytes of the string pointed to by s. + strpbrk() The strpbrk() function returns a pointer to the first occurrence in string s1 of any character from string s2, or -- meem From meem@triplex.East.Sun.COM Wed Nov 8 10:23:50 2006 Received: from sunmail4.Singapore.Sun.COM (sunmail4.Singapore.Sun.COM [129.158.71.19]) by sac.sfbay.sun.com (8.13.6+Sun/8.13.6) with ESMTP id kA8INnb5010421 for ; Wed, 8 Nov 2006 10:23:50 -0800 (PST) Received: from nwk-avmta-1.sfbay.sun.com (nwk-avmta-1.SFBay.Sun.COM [129.149.246.28]) by sunmail4.Singapore.Sun.COM (8.13.4+Sun/8.13.3/ENSMAIL,v2.2) with ESMTP id kA8INhS3028252 for <@sunmail2.sfbay.sun.com:PSARC-EXT@sun.com>; Thu, 9 Nov 2006 02:23:48 +0800 (SGT) Received: from pmxchannel-daemon.nwk-avmta-1.sfbay.Sun.COM by nwk-avmta-1.sfbay.Sun.COM (Sun Java System Messaging Server 6.2 (built Dec 2 2004)) id <0J8F0092BCFN0W00@nwk-avmta-1.sfbay.Sun.COM> for PSARC-EXT@sun.com (ORCPT PSARC-EXT@sun.com); Wed, 08 Nov 2006 10:23:47 -0800 (PST) Received: from triplex.East.Sun.COM ([129.148.174.104]) by nwk-avmta-1.sfbay.Sun.COM (Sun Java System Messaging Server 6.2 (built Dec 2 2004)) with ESMTP id <0J8F00MSNCFLZMB0@nwk-avmta-1.sfbay.Sun.COM> for PSARC-EXT@sun.com (ORCPT PSARC-EXT@sun.com); Wed, 08 Nov 2006 10:23:46 -0800 (PST) Received: from triplex.East.Sun.COM (localhost [127.0.0.1]) by triplex.East.Sun.COM (8.13.8+Sun/8.13.8) with ESMTP id kA8INjI9103501; Wed, 08 Nov 2006 13:23:45 -0500 (EST) Received: (from meem@localhost) by triplex.East.Sun.COM (8.13.8+Sun/8.13.8/Submit) id kA8INirV103498; Wed, 08 Nov 2006 13:23:44 -0500 (EST) Date: Wed, 08 Nov 2006 13:23:44 -0500 From: Peter Memishian Subject: re: PSARC/2006/617 strnlen() To: PSARC-EXT@sun.com Cc: rlhamil@smart.net Message-id: <17746.8368.863894.267863@triplex.East.Sun.COM> MIME-version: 1.0 X-Mailer: VM 7.17 under 21.4 (patch 18) "Social Property" XEmacs Lucid Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7BIT X-PMX-Version: 5.2.0.264296 Status: RO Content-Length: 70 This fast-track was approved during today's PSARC meeting. -- meem