From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754996AbcBWUii (ORCPT ); Tue, 23 Feb 2016 15:38:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42249 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753817AbcBWUih (ORCPT ); Tue, 23 Feb 2016 15:38:37 -0500 From: Jessica Yu To: Andrew Morton Cc: Rasmus Villemoes , Andy Shevchenko , Kees Cook , linux-kernel@vger.kernel.org, Jessica Yu Subject: [PATCH v3] sscanf: implement basic character sets Date: Tue, 23 Feb 2016 15:38:22 -0500 Message-Id: <1456259902-31792-1-git-send-email-jeyu@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Implement basic character sets for the '%[]' conversion specifier. The '%[]' conversion specifier matches a nonempty sequence of characters from the specified set of accepted (or with '^', rejected) characters between the brackets. The substring matched is to be made up of characters in (or not in) the set. This implementation differs from its glibc counterpart in that it does not support character ranges (e.g., 'a-z' or '0-9'), the hyphen '-' is *not* a special character, and the brackets themselves cannot be matched. Signed-off-by: Jessica Yu --- This patch adds support for the '%[' conversion specifier for sscanf(). This is useful in cases where we'd like to match substrings delimited by something other than spaces. The original motivation for this patch actually came from a livepatch discussion (See: https://lkml.org/lkml/2016/2/8/790), where we were trying to come up with a clean way to parse symbol names with substrings delimited by periods and commas. Patch based on linux-next-20160223. v3: - Fix memory leak in error path (kfree() before returning) - Remove redundant condition in while loop - Style fix (*op)() -> op() v2: - Use kstrndup() to copy the character set from fmt instead of using a statically allocated array lib/vsprintf.c | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 525c8e1..983358a 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -2714,6 +2714,47 @@ int vsscanf(const char *buf, const char *fmt, va_list args) num++; } continue; + case '[': + { + char *s = (char *)va_arg(args, char *); + char *set; + size_t (*op)(const char *str, const char *set); + size_t len = 0; + bool negate = (*(fmt) == '^'); + + if (field_width == -1) + field_width = SHRT_MAX; + + op = negate ? &strcspn : &strspn; + if (negate) + fmt++; + + len = strcspn(fmt, "]"); + /* invalid format; stop here */ + if (!len) + return num; + + set = kstrndup(fmt, len, GFP_KERNEL); + if (!set) + return num; + + /* advance fmt past ']' */ + fmt += len + 1; + + len = op(str, set); + /* no matches */ + if (!len) { + kfree(set); + return num; + } + + while (len-- && field_width--) + *s++ = *str++; + *s = '\0'; + kfree(set); + num++; + } + continue; case 'o': base = 8; break; -- 2.4.3