From 7df04f9b8a0adb1575ca0555775ec10860143cbf Mon Sep 17 00:00:00 2001 From: Bruno Haible Date: Fri, 7 Jul 2017 23:35:32 +0200 Subject: vasnprintf: port to macOS 10.13 Improve comments in last commit. --- lib/vasnprintf.c | 17 ++++++++++------- 2 files changed, 11 insertions(+), 7 deletions(-) diff --git a/lib/vasnprintf.c b/lib/vasnprintf.c index fecaf27..2e4eb19 100644 --- a/lib/vasnprintf.c +++ b/lib/vasnprintf.c @@ -4869,10 +4869,9 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp, #endif *fbp = dp->conversion; #if USE_SNPRINTF -# if ! (((__GLIBC__ > 2 \ - || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 3)) \ - && !defined __UCLIBC__) \ - || (defined __APPLE__ && defined __MACH__) \ +# if ! (((__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 3)) \ + && !defined __UCLIBC__) \ + || (defined __APPLE__ && defined __MACH__) \ || ((defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__)) fbp[1] = '%'; fbp[2] = 'n'; @@ -4887,9 +4886,13 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp, in format strings in writable memory may crash the program (if compiled with _FORTIFY_SOURCE=2), so we should avoid it in this situation. */ - /* macOS 10.13 High Sierra behaves like glibc with - _FORTIFY_SOURCE=2, and older macOS releases - presumably do not need %n. */ + /* On Mac OS X 10.3 or newer, we know that snprintf's return + value conforms to ISO C 99: the tests gl_SNPRINTF_RETVAL_C99 + and gl_SNPRINTF_TRUNCATION_C99 pass. + Therefore we can avoid using %n in this situation. + On Mac OS X 10.13 or newer, the use of %n in format strings + in writable memory by default crashes the program, so we + should avoid it in this situation. */ /* On native Windows systems (such as mingw), we can avoid using %n because: - Although the gl_SNPRINTF_TRUNCATION_C99 test fails, -- cgit v1.0-41-gc330