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string: Implement strerror in terms of strerror_l
If the thread is terminated then __libc_thread_freeres will free the storage via __glibc_tls_internal_free. It is only within the calling thread that this matters. It makes strerror MT-safe. Checked on x86-64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu, and s390x-linux-gnu. Tested-by: Carlos O'Donell <carlos@redhat.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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NEWS
5
NEWS
@ -79,6 +79,11 @@ Deprecated and removed features, and other changes affecting compatibility:
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compatibility symbols to support old binaries. All programs should use
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strerror or strerror_r instead.
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* Both strerror and strerror_l now share the same internal buffer in the
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calling thread, meaning that the returned string pointer may be invalided
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or contents might be overwritten on subsequent calls in the same thread or
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if the thread is terminated. It makes strerror MT-safe.
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Changes to build and runtime requirements:
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* powerpc64le requires GCC 7.4 or newer. This is required for supporting
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@ -4,6 +4,7 @@
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/* Some of these are defined as macros in the real string.h, so we must
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prototype them before including it. */
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#include <sys/types.h>
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#include <locale.h>
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extern void *__memccpy (void *__dest, const void *__src,
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int __c, size_t __n);
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@ -50,6 +51,8 @@ extern int __ffs (int __i) __attribute__ ((const));
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extern char *__strerror_r (int __errnum, char *__buf, size_t __buflen);
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extern char *__strerror_l (int __errnum, locale_t __loc);
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/* Called as part of the thread shutdown sequence. */
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void __strerror_thread_freeres (void) attribute_hidden;
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@ -113,6 +116,7 @@ libc_hidden_proto (memmem)
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extern __typeof (memmem) __memmem;
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libc_hidden_proto (__memmem)
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libc_hidden_proto (__ffs)
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libc_hidden_proto (__strerror_l)
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#if IS_IN (libc)
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/* Avoid hidden reference to IFUNC symbol __explicit_bzero_chk. */
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@ -15,29 +15,11 @@
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <libintl.h>
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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/* Return a string describing the errno code in ERRNUM.
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The storage is good only until the next call to strerror.
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Writing to the storage causes undefined behavior. */
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libc_freeres_ptr (static char *buf);
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#include <locale/localeinfo.h>
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char *
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strerror (int errnum)
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{
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char *ret = __strerror_r (errnum, NULL, 0);
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int saved_errno;
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if (__glibc_likely (ret != NULL))
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return ret;
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saved_errno = errno;
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if (buf == NULL)
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buf = malloc (1024);
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__set_errno (saved_errno);
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if (buf == NULL)
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return _("Unknown error");
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return __strerror_r (errnum, buf, 1024);
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return __strerror_l (errnum, __libc_tsd_get (locale_t, LOCALE));
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}
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@ -20,8 +20,7 @@
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/param.h>
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#include <libc-symbols.h>
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#include <errno.h>
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static __thread char *last_value;
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@ -38,8 +37,9 @@ translate (const char *str, locale_t loc)
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/* Return a string describing the errno code in ERRNUM. */
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char *
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strerror_l (int errnum, locale_t loc)
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__strerror_l (int errnum, locale_t loc)
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{
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int saved_errno = errno;
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char *err = (char *) __get_errlist (errnum);
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if (__glibc_unlikely (err == NULL))
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{
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@ -48,11 +48,16 @@ strerror_l (int errnum, locale_t loc)
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translate ("Unknown error ", loc), errnum) == -1)
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last_value = NULL;
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return last_value;
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err = last_value;
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}
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else
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err = (char *) translate (err, loc);
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return (char *) translate (err, loc);
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__set_errno (saved_errno);
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return err;
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}
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weak_alias (__strerror_l, strerror_l)
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libc_hidden_def (__strerror_l)
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void
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__strerror_thread_freeres (void)
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@ -42,7 +42,7 @@ translate (const char *str, locale_t loc)
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/* Return a string describing the errno code in ERRNUM. */
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char *
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strerror_l (int errnum, locale_t loc)
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__strerror_l (int errnum, locale_t loc)
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{
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int system;
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int sub;
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@ -86,6 +86,8 @@ strerror_l (int errnum, locale_t loc)
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return (char *) translate (es->subsystem[sub].codes[code], loc);
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}
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weak_alias (__strerror_l, strerror_l)
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libc_hidden_def (__strerror_l)
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/* This is called when a thread is exiting to free the last_value string. */
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void
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