From c87f0918b01f1c40c0da1fc82bebc0252b932b9d Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Wed, 24 Sep 2025 15:37:08 -0700 Subject: [PROPOSED 2/4] Use strnlen MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * Makefile, NEWS: Mention this. * localtime.c (scrub_abbrs, tzloadbody, tzset_unlocked): * zic.c (newabbr): Prefer strnlen to strlen if we merely want to check whether a string fits. * private.h (strnlen): Define if platform doesn’t. --- Makefile | 1 + NEWS | 3 +++ localtime.c | 9 +++++---- private.h | 12 ++++++++++++ zic.c | 2 +- 5 files changed, 22 insertions(+), 5 deletions(-) diff --git a/Makefile b/Makefile index 6aac7b2d..321b447d 100644 --- a/Makefile +++ b/Makefile @@ -267,6 +267,7 @@ LDLIBS= # -DHAVE_STDINT_H=0 if does not work*+ # -DHAVE_STRFTIME_L if declares locale_t and strftime_l # -DHAVE_STRDUP=0 if your system lacks the strdup function +# -DHAVE_STRNLEN=0 if your system lacks the strnlen function+ # -DHAVE_STRTOLL=0 if your system lacks the strtoll function+ # -DHAVE_SYMLINK=0 if your system lacks the symlink function # -DHAVE_SYS_STAT_H=0 if does not work* diff --git a/NEWS b/NEWS index 2421950e..4f2d08e6 100644 --- a/NEWS +++ b/NEWS @@ -32,6 +32,9 @@ Unreleased, experimental changes It is defined if STD_INSPIRED is defined. (Patch from Dag-Erling Smørgrav.) + tzcode now uses strnlen to improve asymptotic performance a bit. + Compile with -DHAVE_STRNLEN=0 if your platform lacks it. + Changes to commentary The leapseconds file contains commentary about the IERS and NIST diff --git a/localtime.c b/localtime.c index 378694fb..bae8217f 100644 --- a/localtime.c +++ b/localtime.c @@ -460,7 +460,7 @@ scrub_abbrs(struct state *sp) /* Reject overlong abbreviations. */ for (i = 0; i < sp->charcnt - (TZNAME_MAXIMUM + 1); ) { - int len = strlen(&sp->chars[i]); + int len = strnlen(&sp->chars[i], TZNAME_MAXIMUM + 1); if (TZNAME_MAXIMUM < len) return EOVERFLOW; i += len + 1; @@ -549,7 +549,8 @@ tzloadbody(char const *name, struct state *sp, char tzloadflags, #endif if (!doaccess) { char const *dot; - if (sizeof lsp->fullname - sizeof tzdirslash <= strlen(name)) + if (sizeof lsp->fullname - sizeof tzdirslash + <= strnlen(name, sizeof lsp->fullname - sizeof tzdirslash)) return ENAMETOOLONG; /* Create a string "TZDIR/NAME". Using sprintf here @@ -793,7 +794,7 @@ tzloadbody(char const *name, struct state *sp, char tzloadflags, break; } if (! (j < charcnt)) { - int tsabbrlen = strlen(tsabbr); + int tsabbrlen = strnlen(tsabbr, TZ_MAX_CHARS - j); if (j + tsabbrlen < TZ_MAX_CHARS) { strcpy(sp->chars + j, tsabbr); charcnt = j + tsabbrlen + 1; @@ -1474,7 +1475,7 @@ tzset_unlocked(void) { char const *name = getenv("TZ"); struct state *sp = lclptr; - int lcl = name ? strlen(name) < sizeof lcl_TZname : -1; + int lcl = name ? strnlen(name, sizeof lcl_TZname) < sizeof lcl_TZname : -1; if (lcl < 0 ? lcl_is_set < 0 : 0 < lcl_is_set && strcmp(lcl_TZname, name) == 0) diff --git a/private.h b/private.h index b2856e2e..223caf6b 100644 --- a/private.h +++ b/private.h @@ -212,7 +212,19 @@ #undef tzfree #include + #include +#if defined HAVE_STRNLEN && !HAVE_STRNLEN +static size_t +strnlen (char const *s, size_t maxlen) +{ + size_t i; + for (i = 0; i < maxlen && s[i]; i++) + continue; + return i; +} +#endif + #if !PORT_TO_C89 # include #endif diff --git a/zic.c b/zic.c index 854e306b..6bdb039d 100644 --- a/zic.c +++ b/zic.c @@ -3932,7 +3932,7 @@ mp = _("time zone abbreviation differs from POSIX standard"); if (mp != NULL) warning("%s (%s)", mp, string); } - i = strlen(string) + 1; + i = strnlen(string, TZ_MAX_CHARS - charcnt) + 1; if (charcnt + i > TZ_MAX_CHARS) { error(_("too many, or too long, time zone abbreviations")); exit(EXIT_FAILURE); -- 2.48.1