Date: Thu, 24 Aug 2017 01:23:33 +0000 (UTC) From: Kyle Evans <kevans@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r322826 - head/usr.bin/grep Message-ID: <201708240123.v7O1NXTx000502@repo.freebsd.org>
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Author: kevans Date: Thu Aug 24 01:23:33 2017 New Revision: 322826 URL: https://svnweb.freebsd.org/changeset/base/322826 Log: bsdgrep: add a primitive literal matcher fgrep/grep -F will error out at runtime if compiled with a regex(3) that does not define REG_NOSPEC or REG_LITERAL. glibc is one such regex(3) implementation, and as it turns out they don't support literal matching at all. Provide a primitive literal matcher for use with glibc and other implementations that don't support literal matching so that we don't completely lose fgrep/grep -F if compiled against libgnuregex on stable/10, stable/11, or other systems that we don't necessarily support. This is a wholly unoptimized implementation with no plans to optimize it as of now. This is due to both its use-case being primarily on unsupported systems in the near-distant future and that it's reinventing the wheel that we already have available as a feature of regex(3). Reviewed by: cem, emaste, ngie Approved by: emaste (mentor) MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D12056 Modified: head/usr.bin/grep/grep.c head/usr.bin/grep/grep.h head/usr.bin/grep/util.c Modified: head/usr.bin/grep/grep.c ============================================================================== --- head/usr.bin/grep/grep.c Thu Aug 24 01:20:52 2017 (r322825) +++ head/usr.bin/grep/grep.c Thu Aug 24 01:23:33 2017 (r322826) @@ -720,12 +720,19 @@ main(int argc, char *argv[]) case GREP_BASIC: break; case GREP_FIXED: + /* + * regex(3) implementations that support fixed-string searches generally + * define either REG_NOSPEC or REG_LITERAL. Set the appropriate flag + * here. If neither are defined, GREP_FIXED later implies that the + * internal literal matcher should be used. Other cflags that have + * the same interpretation as REG_NOSPEC and REG_LITERAL should be + * similarly added here, and grep.h should be amended to take this into + * consideration when defining WITH_INTERNAL_NOSPEC. + */ #if defined(REG_NOSPEC) cflags |= REG_NOSPEC; #elif defined(REG_LITERAL) cflags |= REG_LITERAL; -#else - errx(2, "literal expressions not supported at compile time"); #endif break; case GREP_EXTENDED: @@ -742,7 +749,11 @@ main(int argc, char *argv[]) r_pattern = grep_calloc(patterns, sizeof(*r_pattern)); /* Don't process any patterns if we have a blank one */ +#ifdef WITH_INTERNAL_NOSPEC + if (!matchall && grepbehave != GREP_FIXED) { +#else if (!matchall) { +#endif /* Check if cheating is allowed (always is for fgrep). */ for (i = 0; i < patterns; ++i) { #ifndef WITHOUT_FASTMATCH Modified: head/usr.bin/grep/grep.h ============================================================================== --- head/usr.bin/grep/grep.h Thu Aug 24 01:20:52 2017 (r322825) +++ head/usr.bin/grep/grep.h Thu Aug 24 01:23:33 2017 (r322826) @@ -57,6 +57,10 @@ extern const char *errstr[]; #define GREP_BASIC 1 #define GREP_EXTENDED 2 +#if !defined(REG_NOSPEC) && !defined(REG_LITERAL) +#define WITH_INTERNAL_NOSPEC +#endif + #define BINFILE_BIN 0 #define BINFILE_SKIP 1 #define BINFILE_TEXT 2 Modified: head/usr.bin/grep/util.c ============================================================================== --- head/usr.bin/grep/util.c Thu Aug 24 01:20:52 2017 (r322825) +++ head/usr.bin/grep/util.c Thu Aug 24 01:23:33 2017 (r322826) @@ -70,7 +70,10 @@ struct parsec { bool binary; /* Binary file? */ }; - +#ifdef WITH_INTERNAL_NOSPEC +static int litexec(const struct pat *pat, const char *string, + size_t nmatch, regmatch_t pmatch[]); +#endif static int procline(struct parsec *pc); static void printline(struct parsec *pc, int sep); static void printline_metadata(struct str *line, int sep); @@ -350,6 +353,67 @@ procfile(const char *fn) return (c); } +#ifdef WITH_INTERNAL_NOSPEC +/* + * Internal implementation of literal string search within a string, modeled + * after regexec(3), for use when the regex(3) implementation doesn't offer + * either REG_NOSPEC or REG_LITERAL. This does not apply in the default FreeBSD + * config, but in other scenarios such as building against libgnuregex or on + * some non-FreeBSD OSes. + */ +static int +litexec(const struct pat *pat, const char *string, size_t nmatch, + regmatch_t pmatch[]) +{ + char *(*strstr_fn)(const char *, const char *); + char *sub, *subject; + const char *search; + size_t idx, n, ofs, stringlen; + + if (cflags & REG_ICASE) + strstr_fn = strcasestr; + else + strstr_fn = strstr; + idx = 0; + ofs = pmatch[0].rm_so; + stringlen = pmatch[0].rm_eo; + if (ofs >= stringlen) + return (REG_NOMATCH); + subject = strndup(string, stringlen); + if (subject == NULL) + return (REG_ESPACE); + for (n = 0; ofs < stringlen;) { + search = (subject + ofs); + if ((unsigned long)pat->len > strlen(search)) + break; + sub = strstr_fn(search, pat->pat); + /* + * Ignoring the empty string possibility due to context: grep optimizes + * for empty patterns and will never reach this point. + */ + if (sub == NULL) + break; + ++n; + /* Fill in pmatch if necessary */ + if (nmatch > 0) { + pmatch[idx].rm_so = ofs + (sub - search); + pmatch[idx].rm_eo = pmatch[idx].rm_so + pat->len; + if (++idx == nmatch) + break; + ofs = pmatch[idx].rm_so + 1; + } else + /* We only needed to know if we match or not */ + break; + } + free(subject); + if (n > 0 && nmatch > 0) + for (n = idx; n < nmatch; ++n) + pmatch[n].rm_so = pmatch[n].rm_eo = -1; + + return (n > 0 ? 0 : REG_NOMATCH); +} +#endif /* WITH_INTERNAL_NOSPEC */ + #define iswword(x) (iswalnum((x)) || (x) == L'_') /* @@ -400,6 +464,11 @@ procline(struct parsec *pc) for (i = 0; i < patterns; i++) { pmatch.rm_so = st; pmatch.rm_eo = pc->ln.len; +#ifdef WITH_INTERNAL_NOSPEC + if (grepbehave == GREP_FIXED) + r = litexec(&pattern[i], pc->ln.dat, 1, &pmatch); + else +#endif #ifndef WITHOUT_FASTMATCH if (fg_pattern[i].pattern) r = fastexec(&fg_pattern[i],
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