gettext.c: remove/reword a mostly-useless comment
Mostly remove the comment I added 5e9637c6297 (i18n: add infrastructure for translating Git with gettext, 2011-11-18). Since then we had a fix in 9c0495d23e6 (gettext.c: detect the vsnprintf bug at runtime, 2013-12-01) so we're not running with the "set back to C locale" hack on any modern system. So having more than 1/4 of the file taken up by a digression about a glibc bug that mostly doesn't happen to anyone anymore is just a needless distraction. Shorten the comment to make a brief mention of the bug, and where to find more info by looking at the git history for this now-removed comment. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Ævar Arnfjörð Bjarmason committed
Jan 11, 2021 at 14:14 UTC
9371c0e9dd54717894e3dd19d36aba06190cb8a0
1 file changed
+15
-79
gettext.c
+15
-79
@@ -87,88 +87,24 @@ static int test_vsnprintf(const char *fmt, ...)
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static void init_gettext_charset(const char *domain)
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{
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- /*
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- This trick arranges for messages to be emitted in the user's
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- requested encoding, but avoids setting LC_CTYPE from the
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- environment for the whole program.
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-
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- This primarily done to avoid a bug in vsnprintf in the GNU C
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- Library [1]. which triggered a "your vsnprintf is broken" error
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- on Git's own repository when inspecting v0.99.6~1 under a UTF-8
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- locale.
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-
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- That commit contains a ISO-8859-1 encoded author name, which
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- the locale aware vsnprintf(3) won't interpolate in the format
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- argument, due to mismatch between the data encoding and the
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- locale.
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-
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- Even if it wasn't for that bug we wouldn't want to use LC_CTYPE at
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- this point, because it'd require auditing all the code that uses C
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- functions whose semantics are modified by LC_CTYPE.
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-
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- But only setting LC_MESSAGES as we do creates a problem, since
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- we declare the encoding of our PO files[2] the gettext
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- implementation will try to recode it to the user's locale, but
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- without LC_CTYPE it'll emit something like this on 'git init'
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- under the Icelandic locale:
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-
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- Bj? til t?ma Git lind ? /hlagh/.git/
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-
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- Gettext knows about the encoding of our PO file, but we haven't
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- told it about the user's encoding, so all the non-US-ASCII
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- characters get encoded to question marks.
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-
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- But we're in luck! We can set LC_CTYPE from the environment
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- only while we call nl_langinfo and
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- bind_textdomain_codeset. That suffices to tell gettext what
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- encoding it should emit in, so it'll now say:
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-
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- Bjó til tóma Git lind í /hlagh/.git/
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-
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- And the equivalent ISO-8859-1 string will be emitted under a
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- ISO-8859-1 locale.
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-
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- With this change way we get the advantages of setting LC_CTYPE
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- (talk to the user in his language/encoding), without the major
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- drawbacks (changed semantics for C functions we rely on).
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-
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- However foreign functions using other message catalogs that
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- aren't using our neat trick will still have a problem, e.g. if
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- we have to call perror(3):
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-
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- #include <stdio.h>
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- #include <locale.h>
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- #include <errno.h>
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-
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- int main(void)
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- {
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- setlocale(LC_MESSAGES, "");
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- setlocale(LC_CTYPE, "C");
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- errno = ENODEV;
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- perror("test");
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- return 0;
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- }
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-
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- Running that will give you a message with question marks:
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-
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- $ LANGUAGE= LANG=de_DE.utf8 ./test
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- test: Kein passendes Ger?t gefunden
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-
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- The vsnprintf bug has been fixed since glibc 2.17.
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-
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- Then we could simply set LC_CTYPE from the environment, which would
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- make things like the external perror(3) messages work.
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-
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- See t/t0203-gettext-setlocale-sanity.sh's "gettext.c" tests for
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- regression tests.
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-
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- 1. http://sourceware.org/bugzilla/show_bug.cgi?id=6530
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- 2. E.g. "Content-Type: text/plain; charset=UTF-8\n" in po/is.po
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- */
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setlocale(LC_CTYPE, "");
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charset = locale_charset();
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bind_textdomain_codeset(domain, charset);
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- /* the string is taken from v0.99.6~1 */
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+
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+ /*
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+ * Work around an old bug fixed in glibc 2.17 (released on
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+ * 2012-12-24), at the cost of potentially making translated
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+ * messages from external functions like perror() emitted in
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+ * the wrong encoding.
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+ *
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+ * The bug affected e.g. git.git's own 7eb93c89651 ([PATCH]
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+ * Simplify git script, 2005-09-07), which is the origin of
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+ * the "David_K\345gedal" test string.
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+ *
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+ * See a much longer comment added to this file in 5e9637c6297
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+ * (i18n: add infrastructure for translating Git with gettext,
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+ * 2011-11-18) for more details.
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+ */
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if (test_vsnprintf("%.*s", 13, "David_K\345gedal") < 0)
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setlocale(LC_CTYPE, "C");
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}