Jaic1/MiniCRT

Source

code from 程序员的自我修养
only work in x86_64-linux

Note

I compile these 32-bit codes on 64-bit machine(x86_64-linux).
For detail, refer Makefile.
In order to do this, there is one place need to be fixed:

argc = *(int *)(ebp_reg + 8);
argv = (char **)(ebp_reg + 12);

They were +4 and +8 before,
but since we are running 32-bit program on x86_64,
the first instruction in mini_crt_entry would be push %rbp,
then rbp would occupy 8 bytes in the stack,
instead of 4 bytes when compiled and linked for 32-bit machine.

Errata

1. In malloc.c's free function, next block's prev may not be updated:

if(next && next->type == HEAP_BLOCK_FREE)
{
    header->size += next->size;
    next = next->next;
    header->next = next;
    // missed in the book
    if(next)
        next->prev = header;
}

2. In printf.c, the type of the first argument of fputc function should be char

int fputc(char c, FILE *stream)
{
    if(fwrite(&c, 1, 1, stream) != 1)
        return EOF;
    else
        return c;
}

3. In tests/test.c, size is not count

fp = fopen("test.txt", "w");
    for (i = 0; i < argv; i++)
    {
        int len = strlen(v[i]);
        fwrite(&len, sizeof(int), 1, fp);
        fwrite(v[i], 1, len, fp);
    }
    fclose(fp);

4. printf not working solution:
   do not define va_list, va_start, va_arg ourself,
   use #include <stdarg.h> instead.

5. fwrite not support writing an int It just uses size*count, so we should just use char to test.

int fwrite(const void *buffer, int size, int count, FILE *stream)
{
    return write((int)stream, buffer, size * count);
}

my test for fwrite(change in fread test too):

fp = fopen("test.txt", "w");
for (i = 0; i < argc; i++)
{
    int len = strlen(v[i]);
    char len_written = len + '0';

    printf("writing %d%s to fd %d\n", len, v[i], fp);
    fwrite(&len_written, 1, 1, fp);
    fwrite(v[i], 1, len, fp);
    fwrite(&newline, 1, 1, fp);
}
fclose(fp);

6. add delete function ld complain about no declaration about operator delete(void*, unsigned int),
   so I add it in new_delete.cpp

void operator delete(void *p, unsigned int)
{
    free(p);
}