Как и заголовок, мне действительно нужна помощь в понимании того, почему этот код обрабатывается в моей системе (linux mint 19, GCC-8.0.1, valgrind-3.13.0, c17) как НЕ действительный код:
#include <stdio.h>
#include <string.h>
void printThis( const char *const ptr );
int main( void) {
char a[10] = "asds";
char b[10] = "1234567890";
strcpy ( a, b );
printThis( a );
}
void printThis( const char *const ptr ){
printf("Copy completed! : %s\n", ptr );
}
Valgrind сообщает о проблеме здесь:
==6973== Memcheck, a memory error detector
==6973== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==6973== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==6973== Command: /home/michi/Templates/Cprogram/bin/Debug/Cprogram
==6973==
==6973== Source and destination overlap in strcpy(0x1ffefffd14, 0x1ffefffd1e)
==6973== at 0x4C32E97: strcpy (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==6973== by 0x108724: main (main.c:12)
==6973==
Copy completed! : 1234567890
==6973==
==6973== HEAP SUMMARY:
==6973== in use at exit: 0 bytes in 0 blocks
==6973== total heap usage: 1 allocs, 1 frees, 1,024 bytes allocated
==6973==
==6973== All heap blocks were freed -- no leaks are possible
==6973==
==6973== For counts of detected and suppressed errors, rerun with: -v
==6973== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
и этот код действителен:
#include <stdio.h>
void strcpy2(char *s, char *t);
void printThis( const char *const ptr );
int main( void) {
char a[10] = "asds";
char b[10] = "1234567890";
strcpy2( a, b );
printThis( a );
}
void strcpy2(char *s, char *t) {
while ( ( *(s++) = *(t++) ) );
}
void printThis( const char *const ptr ){
printf("Copy completed! : %s\n", ptr );
}
Вывод Valgrind:
==7025== Memcheck, a memory error detector
==7025== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==7025== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==7025== Command: /home/michi/Templates/Cprogram/bin/Debug/Cprogram
==7025==
Copy completed! : 1234567890
==7025==
==7025== HEAP SUMMARY:
==7025== in use at exit: 0 bytes in 0 blocks
==7025== total heap usage: 1 allocs, 1 frees, 1,024 bytes allocated
==7025==
==7025== All heap blocks were freed -- no leaks are possible
==7025==
==7025== For counts of detected and suppressed errors, rerun with: -v
==7025== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Скомпилировано с флагами O0, O1, O2 и O3 и GCC:
-Wpedantic -std=c17 -Wall -Wextra -Werror -Wstrict-prototypes -Wmissing-prototypes -Wmisleading-indentation -Wduplicated-cond -Wold-style-definition -Wconversion -Wshadow -Winit-self -Wfloat-equal -Wwrite-strings -O0 -g