On 2013/8/1 8:58, Luis Lavena wrote: > Hello folks, > > As maintainer of RubyInstaller (binary distribution of Ruby on Windows), we > opted to use Ruben's mingw-w64 binary packages as compiler toolchain and also > as > part of our DevKit, to allow users install and compile extensions to the > language. > > A few days ago, a user reported an interesting case that shows issues with > snprintf: > > https://github.com/oneclick/rubyinstaller/issues/186 > > The test case is simple, the following script: > > #include <stdio.h> > #include <string.h> > #include <assert.h> > > char small_buffer[10]; > char *small_text = "123"; > char *big_text = "12345678901234567890"; > > int main(int argc, char *argv[]) > { > int rc; > > // Text fits into buffer: snprintf returns length. > rc = snprintf(small_buffer, sizeof(small_buffer), small_text); > printf("small_text rc = %d\n", rc); > assert(rc == strlen(small_text)); > > // Text too big for buffer: ANSI C99 snprintf should return required length. > // Gnu/Linux follows ANSI C99. > // MinGW is supposed to follow ANSI C99. > // Windows is broken and fails this test. > rc = snprintf(small_buffer, sizeof(small_buffer), big_text); > printf("big_text rc = %d\n", rc); > assert(rc > 0); > > return(0); > } > > > Compiled with mingw 4.7.2 (std=c99 or ANSI), this is the output: > > C:\Users\Luis\Code\_sandbox\scripts>gcc --version > gcc (GCC) 4.7.2 > > C:\Users\Luis\Code\_sandbox\scripts>test-472-mingw.exe > small_text rc = 3 > big_text rc = 20 > > While either Ruben's or mingw-builds resulted in: > > C:\Users\Luis\Code\_sandbox\scripts>test-472-32.exe > small_text rc = 3 > big_text rc = -1 > Assertion failed! > > Program: C:\Users\Luis\Code\_sandbox\scripts\test-472-32.exe > File: test.snprintf.c, Line 24 > > Expression: rc > 0 > > Tested against: > > Ruben's 4.7.2 (packages): > i686-w64-mingw32-gcc-4.7.2-release-win32_rubenvb.7z > i686_64-w64-mingw32-mingw-w64-update-v2.0.7_rubenvb.7z > > mingw-builds 4.7.3 (packages): > x32-4.7.3-release-win32-sjlj-rev1.7z > > Definitely I'm missing something here, so will appreciate any hint and > suggestion. > > Thank you in advance. > -- > Luis Lavena > AREA 17 > -
This is expected. You must define __USE_MINGW_ANSI_STDIO or _POSIX yourself. Here is the test case: C:\var\building>gcc --version gcc (GCC) 4.7.4 20130731 (prerelease) Copyright (C) 2012 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. C:\var\building>gcc -O2 test.c C:\var\building>a small_text rc = 3 big_text rc = -1 Assertion failed! Program: C:\var\building\a.exe File: test.c, Line 24 Expression: rc > 0 This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. C:\var\building>gcc -O2 -D __USE_MINGW_ANSI_STDIO test.c C:\var\building>a small_text rc = 3 big_text rc = 20 C:\var\building>gcc -O2 -D _POSIX test.c C:\var\building>a small_text rc = 3 big_text rc = 20 Or you can modify _mingw_mac.h, define __USE_MINGW_ANSI_STDIO or _POSIX .
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