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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <87r1v4cmmf.fsf@oldenburg2.str.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Adhemerval Zanella via Libc-alpha Reply-To: Adhemerval Zanella Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" On 28/05/2020 08:41, Florian Weimer wrote: >> diff --git a/string/strerror.c b/string/strerror.c >> index 283ab70f91..35c749016e 100644 >> --- a/string/strerror.c >> +++ b/string/strerror.c >> @@ -15,29 +15,11 @@ >> License along with the GNU C Library; if not, see >> . */ >> >> -#include >> -#include >> #include >> -#include >> - >> -/* Return a string describing the errno code in ERRNUM. >> - The storage is good only until the next call to strerror. >> - Writing to the storage causes undefined behavior. */ >> -libc_freeres_ptr (static char *buf); >> +#include >> >> char * >> strerror (int errnum) >> { >> - char *ret = __strerror_r (errnum, NULL, 0); >> - int saved_errno; >> - >> - if (__glibc_likely (ret != NULL)) >> - return ret; >> - saved_errno = errno; >> - if (buf == NULL) >> - buf = malloc (1024); >> - __set_errno (saved_errno); >> - if (buf == NULL) >> - return _("Unknown error"); >> - return __strerror_r (errnum, buf, 1024); >> + return __strerror_l (errnum, __libc_tsd_get (locale_t, LOCALE)); >> } > > Why is it okay to share the buffer between strerror and strerror_l? > POSIX is a bit unclear about this. Practically speaking, it should be > okay. But perhaps there should be a NEWS entry. POSIX states the strerror buffer *might* be overwritten by a subsequent call to strerror *or* strerror_l (as an extension to the ISO C). So my understanding is an implementation has the freedom to implement strerror on top of strerror_l and share its internal buffer (bionic and musl seem to share this understanding was well). What about add this NEWS entry at deprecated and removed features: * Both strerror and strerror_l now share the same internal buffer, meaning that the returned string pointer might be invalidated or contents might be overwritten in subsequent calls of any symbol. > > Thanks, > Florian >