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From: "Johannes Schindelin via GitGitGadget" <>
Cc: "Johannes Schindelin" <>,
	"Matthias Aßhauer" <>
Subject: [PATCH] mingw: use modern strftime implementation if possible
Date: Wed, 08 Apr 2020 17:58:49 +0000	[thread overview]
Message-ID: <> (raw)

From: =?UTF-8?q?Matthias=20A=C3=9Fhauer?= <>

Microsoft introduced a new "Universal C Runtime Library" (UCRT) with
Visual Studio 2015. The UCRT comes with a new strftime() implementation
that supports more date formats. We link git against the older
"Microsoft Visual C Runtime Library" (MSVCRT), so to use the UCRT
strftime() we need to load it from ucrtbase.dll using

Most supported Windows systems should have recieved the UCRT via Windows
update, but in some cases only MSVCRT might be available. In that case
we fall back to using that implementation.

With this change, it is possible to use e.g. the `%g` and `%V` date
format specifiers, e.g.

	git show -s --format=%cd --date=format:‘%g.%V’ HEAD

Without this change, the user would see this error message on Windows:

	fatal: invalid strftime format: '‘%g.%V’'

This fixes

Signed-off-by: Matthias Aßhauer <>
Signed-off-by: Johannes Schindelin <>
    Use a modern strftime() on Windows when available
    This is another contribution that came in via Git for Windows.

Fetch-It-Via: git fetch pr-git-753/dscho/mingw-modern-strftime-v1

 compat/mingw.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index d14065d60ec..2136744af35 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -964,7 +964,16 @@ int mingw_utime (const char *file_name, const struct utimbuf *times)
 size_t mingw_strftime(char *s, size_t max,
 		      const char *format, const struct tm *tm)
-	size_t ret = strftime(s, max, format, tm);
+	/* a pointer to the original strftime in case we can't find the UCRT version */
+	static size_t (*fallback)(char *, size_t, const char *, const struct tm *) = strftime;
+	size_t ret;
+	DECLARE_PROC_ADDR(ucrtbase.dll, size_t, strftime, char *, size_t,
+		const char *, const struct tm *);
+	if (INIT_PROC_ADDR(strftime))
+		ret = strftime(s, max, format, tm);
+	else
+		ret = fallback(s, max, format, tm);
 	if (!ret && errno == EINVAL)
 		die("invalid strftime format: '%s'", format);

base-commit: 9fadedd637b312089337d73c3ed8447e9f0aa775

             reply	other threads:[~2020-04-08 17:58 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-08 17:58 Johannes Schindelin via GitGitGadget [this message]
2020-04-08 19:14 ` Junio C Hamano
2020-04-10 14:39   ` Johannes Schindelin

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