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
-
Perfection in design is achieved not when there is nothing more to add,
but rather when there is nothing more to take away.
Antoine de Saint-Exupéry
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