Looking for a function which produces the internationalized description of an errno value, with the two additional requirements that - it should be multithread-safe, - it should be easy to use, I didn't find any answer in POSIX or gnulib.
https://man7.org/linux/man-pages/man3/strerror.3.html lists a few functions, but: - strerror is not multithread-safe, - strerrordesc_np returns the English description, not internationalized, - strerror_l requires a locale_t object and thus does not work for the current locale, - strerror_r is not easy to use, because . it requires the caller to provide a preallocated buffer, . it comes in two variants (POSIX and GNU). I considered adding a function xstrerror that would return the string from strerror_r in a per-thread static buffer. But this return convention has a pitfall: if the returned pointer ever gets passed to a different thread, value corruption will occur, that is hard to detect and to debug. (glibc's inet_ntoa function uses this return convention; but that does not make it any more reliable.) So, the best approach is still a function that returns the value in storage with indefinite extent, namely malloc()ed. I picked a 2-arguments function, rather than a 1-argument function, because that's more useful in practice. There's a potential conflict with the 1-argument function named xstrerror from libiberty (GCC/binutils/gdb). The migration is simple: xstrerror_libiberty (errnum) == xstrerror_gnulib (NULL, errnum). 2023-10-05 Bruno Haible <br...@clisp.org> xstrerror: Add tests. * tests/test-xstrerror.c: New file. * modules/xstrerror-tests: New file. xstrerror: New module. * lib/xstrerror.h: New file. * lib/xstrerror.c: New file. * modules/xstrerror: New file. * modules/strerror_r-posix (configure.ac): Update comment.
>From 6d20768e5a08a393aee4099419794e0cca495967 Mon Sep 17 00:00:00 2001 From: Bruno Haible <br...@clisp.org> Date: Thu, 5 Oct 2023 18:01:05 +0200 Subject: [PATCH 1/2] xstrerror: New module. * lib/xstrerror.h: New file. * lib/xstrerror.c: New file. * modules/xstrerror: New file. * modules/strerror_r-posix (configure.ac): Update comment. --- ChangeLog | 8 ++++++ lib/xstrerror.c | 59 ++++++++++++++++++++++++++++++++++++++++ lib/xstrerror.h | 45 ++++++++++++++++++++++++++++++ modules/strerror_r-posix | 2 +- modules/xstrerror | 26 ++++++++++++++++++ 5 files changed, 139 insertions(+), 1 deletion(-) create mode 100644 lib/xstrerror.c create mode 100644 lib/xstrerror.h create mode 100644 modules/xstrerror diff --git a/ChangeLog b/ChangeLog index f09de5233e..b8aefaf222 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,11 @@ +2023-10-05 Bruno Haible <br...@clisp.org> + + xstrerror: New module. + * lib/xstrerror.h: New file. + * lib/xstrerror.c: New file. + * modules/xstrerror: New file. + * modules/strerror_r-posix (configure.ac): Update comment. + 2023-10-05 Paul Eggert <egg...@cs.ucla.edu> isnan: slightly simplify configuration diff --git a/lib/xstrerror.c b/lib/xstrerror.c new file mode 100644 index 0000000000..d00b996627 --- /dev/null +++ b/lib/xstrerror.c @@ -0,0 +1,59 @@ +/* Return diagnostic string based on error code. + Copyright (C) 2023 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + +#include <config.h> + +/* Specification. */ +#include "xstrerror.h" + +#include <string.h> + +#include "xvasprintf.h" +#include "xalloc.h" +#include "gettext.h" + +#define _(msgid) gettext (msgid) + +char * +xstrerror (const char *message, int errnum) +{ + /* Get the internationalized description of errnum, + in a stack-allocated buffer. */ + const char *errdesc; + char errbuf[1024]; +#if !GNULIB_STRERROR_R_POSIX && STRERROR_R_CHAR_P + errdesc = strerror_r (errnum, errbuf, sizeof errbuf); +#else + if (strerror_r (errnum, errbuf, sizeof errbuf) == 0) + errdesc = errbuf; + else + errdesc = NULL; +#endif + if (errdesc == NULL) + errdesc = _("Unknown system error"); + + if (message != NULL) + { + /* Allow e.g. French translators to insert a space before the colon. */ + char *result = xasprintf (_("%s: %s"), message, errdesc); + if (result == NULL) + /* Probably a buggy translation. Use a safe fallback. */ + result = xasprintf ("%s%s%s", message, ": ", errdesc); + return result; + } + else + return xstrdup (errdesc); +} diff --git a/lib/xstrerror.h b/lib/xstrerror.h new file mode 100644 index 0000000000..95beb1d64a --- /dev/null +++ b/lib/xstrerror.h @@ -0,0 +1,45 @@ +/* Return diagnostic string based on error code. + Copyright (C) 2023 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + +#ifndef _XSTRERROR_H +#define _XSTRERROR_H + +/* This file uses _GL_ATTRIBUTE_MALLOC, _GL_ATTRIBUTE_RETURNS_NONNULL. */ +#if !_GL_CONFIG_H_INCLUDED + #error "Please include config.h first." +#endif + +/* Get 'free'. */ +#include <stdlib.h> + +#ifdef __cplusplus +extern "C" { +#endif + +/* Return a freshly allocated diagnostic string that contains a given string + MESSAGE and the (internationalized) description of the error code ERRNUM. + Upon [ENOMEM] memory allocation error, call xalloc_die. + + This function is multithread-safe. */ +extern char *xstrerror (const char *message, int errnum) + _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_DEALLOC_FREE + _GL_ATTRIBUTE_RETURNS_NONNULL; + +#ifdef __cplusplus +} +#endif + +#endif /* _XSTRERROR_H */ diff --git a/modules/strerror_r-posix b/modules/strerror_r-posix index 25f049365a..779a821e9e 100644 --- a/modules/strerror_r-posix +++ b/modules/strerror_r-posix @@ -19,7 +19,7 @@ AS_IF([test $HAVE_DECL_STRERROR_R = 0 || test $REPLACE_STRERROR_R = 1], [ gl_PREREQ_STRERROR_R ]) gl_STRING_MODULE_INDICATOR([strerror_r]) -dnl For the modules argp, error. +dnl For the modules argp, error, xstrerror. gl_MODULE_INDICATOR([strerror_r-posix]) Makefile.am: diff --git a/modules/xstrerror b/modules/xstrerror new file mode 100644 index 0000000000..927d4c74a7 --- /dev/null +++ b/modules/xstrerror @@ -0,0 +1,26 @@ +Description: +xstrerror() function: return diagnostic string based on error code. +Multithread-safe. With out-of-memory checking. + +Files: +lib/xstrerror.h +lib/xstrerror.c + +Depends-on: +strerror_r-posix +xalloc +xvasprintf + +configure.ac: + +Makefile.am: +lib_SOURCES += xstrerror.c + +Include: +"xstrerror.h" + +License: +GPL + +Maintainer: +all -- 2.34.1
>From 70c869be3fcd5da3813a73520dc6bf5b91d68afd Mon Sep 17 00:00:00 2001 From: Bruno Haible <br...@clisp.org> Date: Thu, 5 Oct 2023 18:02:26 +0200 Subject: [PATCH 2/2] xstrerror: Add tests. * tests/test-xstrerror.c: New file. * modules/xstrerror-tests: New file. --- ChangeLog | 4 ++++ modules/xstrerror-tests | 12 +++++++++++ tests/test-xstrerror.c | 45 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 61 insertions(+) create mode 100644 modules/xstrerror-tests create mode 100644 tests/test-xstrerror.c diff --git a/ChangeLog b/ChangeLog index b8aefaf222..6df9aaaef7 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,9 @@ 2023-10-05 Bruno Haible <br...@clisp.org> + xstrerror: Add tests. + * tests/test-xstrerror.c: New file. + * modules/xstrerror-tests: New file. + xstrerror: New module. * lib/xstrerror.h: New file. * lib/xstrerror.c: New file. diff --git a/modules/xstrerror-tests b/modules/xstrerror-tests new file mode 100644 index 0000000000..24a5fc9a10 --- /dev/null +++ b/modules/xstrerror-tests @@ -0,0 +1,12 @@ +Files: +tests/test-xstrerror.c +tests/macros.h + +Depends-on: + +configure.ac: + +Makefile.am: +TESTS += test-xstrerror +check_PROGRAMS += test-xstrerror +test_xstrerror_LDADD = $(LDADD) $(LIBINTL) diff --git a/tests/test-xstrerror.c b/tests/test-xstrerror.c new file mode 100644 index 0000000000..d725aa1c94 --- /dev/null +++ b/tests/test-xstrerror.c @@ -0,0 +1,45 @@ +/* Test of xstrerror function. + Copyright (C) 2023 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + +/* Written by Bruno Haible <br...@clisp.org>, 2023. */ + +#include <config.h> + +#include "xstrerror.h" + +#include <errno.h> +#include <stdlib.h> +#include <string.h> + +#include "macros.h" + +int +main () +{ + /* Test in the "C" locale. */ + { + char *s = xstrerror ("can't steal", EACCES); + ASSERT (strcmp (s, "can't steal: Permission denied") == 0); + free (s); + } + { + char *s = xstrerror (NULL, EACCES); + ASSERT (strcmp (s, "Permission denied") == 0); + free (s); + } + + return 0; +} -- 2.34.1
