From 28aff047818eb1726394296d27b9c7885340bead Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Thu, 14 May 2020 17:44:15 -0300 Subject: 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 Reviewed-by: Carlos O'Donell --- NEWS | 5 +++++ include/string.h | 4 ++++ string/strerror.c | 22 ++-------------------- string/strerror_l.c | 15 ++++++++++----- sysdeps/mach/strerror_l.c | 4 +++- 5 files changed, 24 insertions(+), 26 deletions(-) diff --git a/NEWS b/NEWS index 482d2253e0..5d399293ba 100644 --- a/NEWS +++ b/NEWS @@ -79,6 +79,11 @@ Deprecated and removed features, and other changes affecting compatibility: compatibility symbols to support old binaries. All programs should use strerror or strerror_r instead. +* Both strerror and strerror_l now share the same internal buffer in the + calling thread, meaning that the returned string pointer may be invalided + or contents might be overwritten on subsequent calls in the same thread or + if the thread is terminated. It makes strerror MT-safe. + Changes to build and runtime requirements: * powerpc64le requires GCC 7.4 or newer. This is required for supporting diff --git a/include/string.h b/include/string.h index 4d622f1c03..3a33327cc0 100644 --- a/include/string.h +++ b/include/string.h @@ -4,6 +4,7 @@ /* Some of these are defined as macros in the real string.h, so we must prototype them before including it. */ #include +#include extern void *__memccpy (void *__dest, const void *__src, int __c, size_t __n); @@ -50,6 +51,8 @@ extern int __ffs (int __i) __attribute__ ((const)); extern char *__strerror_r (int __errnum, char *__buf, size_t __buflen); +extern char *__strerror_l (int __errnum, locale_t __loc); + /* Called as part of the thread shutdown sequence. */ void __strerror_thread_freeres (void) attribute_hidden; @@ -113,6 +116,7 @@ libc_hidden_proto (memmem) extern __typeof (memmem) __memmem; libc_hidden_proto (__memmem) libc_hidden_proto (__ffs) +libc_hidden_proto (__strerror_l) #if IS_IN (libc) /* Avoid hidden reference to IFUNC symbol __explicit_bzero_chk. */ 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)); } diff --git a/string/strerror_l.c b/string/strerror_l.c index 309f42e66b..017bd14b99 100644 --- a/string/strerror_l.c +++ b/string/strerror_l.c @@ -20,8 +20,7 @@ #include #include #include -#include -#include +#include static __thread char *last_value; @@ -38,8 +37,9 @@ translate (const char *str, locale_t loc) /* Return a string describing the errno code in ERRNUM. */ char * -strerror_l (int errnum, locale_t loc) +__strerror_l (int errnum, locale_t loc) { + int saved_errno = errno; char *err = (char *) __get_errlist (errnum); if (__glibc_unlikely (err == NULL)) { @@ -48,11 +48,16 @@ strerror_l (int errnum, locale_t loc) translate ("Unknown error ", loc), errnum) == -1) last_value = NULL; - return last_value; + err = last_value; } + else + err = (char *) translate (err, loc); - return (char *) translate (err, loc); + __set_errno (saved_errno); + return err; } +weak_alias (__strerror_l, strerror_l) +libc_hidden_def (__strerror_l) void __strerror_thread_freeres (void) diff --git a/sysdeps/mach/strerror_l.c b/sysdeps/mach/strerror_l.c index f514af341e..b6c9fdbe80 100644 --- a/sysdeps/mach/strerror_l.c +++ b/sysdeps/mach/strerror_l.c @@ -42,7 +42,7 @@ translate (const char *str, locale_t loc) /* Return a string describing the errno code in ERRNUM. */ char * -strerror_l (int errnum, locale_t loc) +__strerror_l (int errnum, locale_t loc) { int system; int sub; @@ -86,6 +86,8 @@ strerror_l (int errnum, locale_t loc) return (char *) translate (es->subsystem[sub].codes[code], loc); } +weak_alias (__strerror_l, strerror_l) +libc_hidden_def (__strerror_l) /* This is called when a thread is exiting to free the last_value string. */ void -- cgit 1.4.1