snprintf compile error

[Crashpilot1000]

Hi!
I was just playing around with snprintf because I read an advice that it is generally safer to use in applications because of the possible size limitation and avoiding writing out of buffer.
So I tried to compile an adapted example from here: http://www.cplusplus.com/reference/cstdio/snprintf/
(for later usage in my oled part like here: https://github.com/Crashpilot1000/HarakiriWebstore1/blob/master/src/drv_i2c_lcd.c#L349)

This: (taken from cplusplus.com example)

..
char line[100];
snprintf (line, sizeof(line), "The half of %d is %d", 60, 60/2 );
..
Produced:
/../../../../arm-none-eabi/lib/armv7-m\libc.a(lib_a-sbrkr.o): In function `_sbrk_r':
sbrkr.c:(.text._sbrk_r+0xc): undefined reference to `_sbrk'

Example from my github https://github.com/Crashpilot1000/HarakiriWebstore1/blob/master/src/drv_i2c_lcd.c#L350
this works of course: ... else sprintf(line, "SAT : - FIX : - ");
this ALSO works: ... else snprintf(line, sizeof(line), "SAT : - FIX : - ");
But this doesn't work (same error in the fist line):
    if (FEATURE_GPS) snprintf(line, sizeof(line), "SAT : %d FIX : %d ", GPS_satnum, GPS_fix); // snprintf doesn't work here
    else snprintf(line, sizeof(line), "SAT : - FIX : - ");

I am compiling for cortex-m3 using gcc-arm-none-eabi-4_9-2015q1-20150306-win32 not sure if that is a bug in gcc or between chair and keyboard.
Cheers Rob

[Tony Liu (mrtoniliu)]

Hi,

Could you provide the command you use to compile and link the example?

BR,
Tony

[Crashpilot1000 (r-balko)]

Thanks for looking into this but I think the problem is somewhere inside the makefile / linking process https://github.com/Crashpilot1000/HarakiriWebstore1/blob/master/Makefile. I am still using the makefile from baseflight that is a couple of years old. Primarily I was wondering why snprintf was working in the first place but then stumbeled about additional parameters. I reverted back to sprintf that roots back to this: https://github.com/Crashpilot1000/HarakiriWebstore1/blob/master/src/printf.c and rechecked my buffersizes so everything ok here. I don't have the knowledge to comment any further but I stongly believe that it is not the problem of this toolchain here. So my apologies and please close / delete this issue/bugreport.
Cheers Rob.