# [PATCH 1/2] MSVC: vsnprintf in Visual Studio 2015 doesn't need SNPRINTF_SIZE_CORR any more 7 messages from 2016-03-29 to 2016-03-30. Participants: Sven Strickroth, Junio C Hamano, Sebastian Schuberth, Johannes Schindelin. Thread: https://gitlist.dev/t/41863 ## Sven Strickroth, 2016-03-29 16:25 Subject: [PATCH 1/2] MSVC: vsnprintf in Visual Studio 2015 doesn't need SNPRINTF_SIZE_CORR any more Message-ID: <56FAAC78.2040304@cs-ware.de> URL: https://gitlist.dev/e/56FAAC78.2040304%40cs-ware.de ``` In MSVC2015 the behavior of vsnprintf was changed. W/o this fix there is one character missing at the end. Signed-off-by: Sven Strickroth --- compat/snprintf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/compat/snprintf.c b/compat/snprintf.c index 42ea1ac..0b11688 100644 --- a/compat/snprintf.c +++ b/compat/snprintf.c @@ -9,7 +9,7 @@ * always have room for a trailing NUL byte. */ #ifndef SNPRINTF_SIZE_CORR -#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) +#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) && (!defined(_MSC_VER) || _MSC_VER < 1900) #define SNPRINTF_SIZE_CORR 1 #else #define SNPRINTF_SIZE_CORR 0 -- 2.7.4.windows.1 ``` ## Junio C Hamano, 2016-03-29 16:43 Subject: Re: [PATCH 1/2] MSVC: vsnprintf in Visual Studio 2015 doesn't need SNPRINTF_SIZE_CORR any more Message-ID: URL: https://gitlist.dev/e/xmqqio05z12u.fsf%40gitster.mtv.corp.google.com In-Reply-To: <56FAAC78.2040304@cs-ware.de> ``` Sven Strickroth writes: > In MSVC2015 the behavior of vsnprintf was changed. > W/o this fix there is one character missing at the end. > > Signed-off-by: Sven Strickroth > --- Thanks. I am not qualified to judge the correctness of the assertion that MSVC at or more recent than version 1900 does not need the correction and will wait for Windows folks to Ack. Thanks. > compat/snprintf.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/compat/snprintf.c b/compat/snprintf.c > index 42ea1ac..0b11688 100644 > --- a/compat/snprintf.c > +++ b/compat/snprintf.c > @@ -9,7 +9,7 @@ > * always have room for a trailing NUL byte. > */ > #ifndef SNPRINTF_SIZE_CORR > -#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) > +#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) && (!defined(_MSC_VER) || _MSC_VER < 1900) > #define SNPRINTF_SIZE_CORR 1 > #else > #define SNPRINTF_SIZE_CORR 0 ``` ## Sebastian Schuberth, 2016-03-29 19:09 Subject: Re: [PATCH 1/2] MSVC: vsnprintf in Visual Studio 2015 doesn't need SNPRINTF_SIZE_CORR any more Message-ID: URL: https://gitlist.dev/e/CAHGBnuP1Y1F-CrQJx9zNKSv1KP7gH86WSKo7tbmcYT3Vf2cQ_g%40mail.gmail.com In-Reply-To: <56FAAC78.2040304@cs-ware.de> ``` On Tue, Mar 29, 2016 at 6:25 PM, Sven Strickroth wrote: > In MSVC2015 the behavior of vsnprintf was changed. > W/o this fix there is one character missing at the end. How about adding a link to [1] in the commit message and quoting the central "Beginning with the UCRT in Visual Studio 2015 and Windows 10, vsnprintf is no longer identical to _vsnprintf. The vsnprintf function complies with the C99 standard; _vnsprintf is retained for backward compatibility" statement? [1] https://msdn.microsoft.com/en-us/library/1kt27hek.aspx -- Sebastian Schuberth ``` ## Sven Strickroth, 2016-03-29 19:13 Subject: Re: [PATCH 1/2] MSVC: vsnprintf in Visual Studio 2015 doesn't need SNPRINTF_SIZE_CORR any more Message-ID: <56FAD3DD.4060009@cs-ware.de> URL: https://gitlist.dev/e/56FAD3DD.4060009%40cs-ware.de In-Reply-To: ``` "Beginning with the UCRT in Visual Studio 2015 and Windows 10, vsnprintf is no longer identical to _vsnprintf. The vsnprintf function complies with the C99 standard; _vnsprintf is retained for backward compatibility" [1] W/o this fix there is one character missing at the end. [1] https://msdn.microsoft.com/en-us/library/1kt27hek.aspx Signed-off-by: Sven Strickroth --- compat/snprintf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/compat/snprintf.c b/compat/snprintf.c index 42ea1ac..0b11688 100644 --- a/compat/snprintf.c +++ b/compat/snprintf.c @@ -9,7 +9,7 @@ * always have room for a trailing NUL byte. */ #ifndef SNPRINTF_SIZE_CORR -#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) +#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) && (!defined(_MSC_VER) || _MSC_VER < 1900) #define SNPRINTF_SIZE_CORR 1 #else #define SNPRINTF_SIZE_CORR 0 -- 2.7.4.windows.1 ``` ## Sebastian Schuberth, 2016-03-29 19:20 Subject: Re: [PATCH 1/2] MSVC: vsnprintf in Visual Studio 2015 doesn't need SNPRINTF_SIZE_CORR any more Message-ID: URL: https://gitlist.dev/e/CAHGBnuNkuiyk1uvJqT1_1UWOhpVTg%2BTxJ2QvepuMBpvOD8AyFw%40mail.gmail.com In-Reply-To: <56FAD3DD.4060009@cs-ware.de> ``` On Tue, Mar 29, 2016 at 9:13 PM, Sven Strickroth wrote: > diff --git a/compat/snprintf.c b/compat/snprintf.c > index 42ea1ac..0b11688 100644 > --- a/compat/snprintf.c > +++ b/compat/snprintf.c > @@ -9,7 +9,7 @@ > * always have room for a trailing NUL byte. > */ > #ifndef SNPRINTF_SIZE_CORR > -#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) > +#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) && (!defined(_MSC_VER) || _MSC_VER < 1900) > #define SNPRINTF_SIZE_CORR 1 > #else > #define SNPRINTF_SIZE_CORR 0 I wonder if the logic is (and was) sensible here. We assume that every non-__GNUC__ and non-_MSC_VER compiler on Windows requires the correction. Wouldn't it make sense to not assume requiring the correction unless we know the compiler has this bug? That is, shouldn't this better say #if defined(WIN32) && (defined(__GNUC__) && __GNUC__ < 4) || (defined(_MSC_VER) && _MSC_VER < 1900)) #define SNPRINTF_SIZE_CORR 1 #else #define SNPRINTF_SIZE_CORR 0 -- Sebastian Schuberth ``` ## Johannes Schindelin, 2016-03-30 07:49 Subject: Re: [PATCH 1/2] MSVC: vsnprintf in Visual Studio 2015 doesn't need SNPRINTF_SIZE_CORR any more Message-ID: URL: https://gitlist.dev/e/alpine.DEB.2.20.1603300946410.4690%40virtualbox In-Reply-To: ``` Hi Sven & Sebastian, On Tue, 29 Mar 2016, Sebastian Schuberth wrote: > On Tue, Mar 29, 2016 at 9:13 PM, Sven Strickroth wrote: ACK on the patch. > > diff --git a/compat/snprintf.c b/compat/snprintf.c > > index 42ea1ac..0b11688 100644 > > --- a/compat/snprintf.c > > +++ b/compat/snprintf.c > > @@ -9,7 +9,7 @@ > > * always have room for a trailing NUL byte. > > */ > > #ifndef SNPRINTF_SIZE_CORR > > -#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) > > +#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) && (!defined(_MSC_VER) || _MSC_VER < 1900) > > #define SNPRINTF_SIZE_CORR 1 > > #else > > #define SNPRINTF_SIZE_CORR 0 > > I wonder if the logic is (and was) sensible here. We assume that every > non-__GNUC__ and non-_MSC_VER compiler on Windows requires the > correction. Wouldn't it make sense to not assume requiring the > correction unless we know the compiler has this bug? That is, > shouldn't this better say > > #if defined(WIN32) && (defined(__GNUC__) && __GNUC__ < 4) || > (defined(_MSC_VER) && _MSC_VER < 1900)) > #define SNPRINTF_SIZE_CORR 1 > #else > #define SNPRINTF_SIZE_CORR 0 Since the standard on Windows always was MS Visual C, it should be assumed that compilers *other* than GCC followed Visual C's lead. Of course, evidence speaks louder than assumptions. Therefore I would prefer to keep the current version, at least until we encounter a case where it is incorrect. Thanks, Johannes ``` ## Sebastian Schuberth, 2016-03-30 07:57 Subject: Re: [PATCH 1/2] MSVC: vsnprintf in Visual Studio 2015 doesn't need SNPRINTF_SIZE_CORR any more Message-ID: URL: https://gitlist.dev/e/CAHGBnuOu9BMfDjmozMHSGKCaA5sYYHYmPupL2-51has4rv-MqA%40mail.gmail.com In-Reply-To: ``` On Wed, Mar 30, 2016 at 9:49 AM, Johannes Schindelin wrote: >> > #ifndef SNPRINTF_SIZE_CORR >> > -#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) >> > +#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4) && (!defined(_MSC_VER) || _MSC_VER < 1900) >> > #define SNPRINTF_SIZE_CORR 1 >> > #else >> > #define SNPRINTF_SIZE_CORR 0 >> >> I wonder if the logic is (and was) sensible here. We assume that every >> non-__GNUC__ and non-_MSC_VER compiler on Windows requires the >> correction. Wouldn't it make sense to not assume requiring the >> correction unless we know the compiler has this bug? That is, >> shouldn't this better say >> >> #if defined(WIN32) && (defined(__GNUC__) && __GNUC__ < 4) || >> (defined(_MSC_VER) && _MSC_VER < 1900)) >> #define SNPRINTF_SIZE_CORR 1 >> #else >> #define SNPRINTF_SIZE_CORR 0 > > Since the standard on Windows always was MS Visual C, it should be assumed > that compilers *other* than GCC followed Visual C's lead. > > Of course, evidence speaks louder than assumptions. > > Therefore I would prefer to keep the current version, at least until we > encounter a case where it is incorrect. Fine with me. It's probably better not to change the logic as we wouldn't know whether this would break things for some exotic compiler currently in use to compile Git. Also ACK from my side on the path then. -- Sebastian Schuberth ```