trace/util.c

static u64
get_address_of_subroutine(struct mi_process proc, char *sr)
{
    for (int i = 0; i < proc.debug.func_count; ++i) {
        struct mi_function *func = proc.debug.functions + i;
        if (0 == strcmp(func->name, sr)) {
            return(func->offset);
        }
    }
    
    return(0);
}

static struct mi_sourcepoint *
pc_to_sourcepoint(struct mi_process proc, u64 pc)
{
    // NOTE: find first point BIGGER that pc, return the sourcepoint just before that
    // TODO: binary search
    for (int i = 0; i < proc.debug.sp_count; ++i) {
        struct mi_sourcepoint *point = proc.debug.sp_table + i;
        if (point->pc > pc) {
            return(proc.debug.sp_table + i - 1);
        }
    }
    
    return(0);
}

static void
print_word_at_address(int child, u64 address)
{
    long word = ptrace(PTRACE_PEEKDATA, child, address, NULL);
    u8 nb[4];
    memcpy(nb, &word, 4);
    printf("word at %#018lx: {%x %x %x %x}\n", address, nb[0], nb[1], nb[2], nb[3]);
}

static struct mi_buffer
read_file_mmap(char *path)
{
    struct mi_buffer result = { 0 };
    
    struct stat s;
    int fd = open(path, O_RDONLY);
    assert(fd != -1);
    fstat(fd, &s);
    
    result.data = mmap(0, s.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
    result.size = s.st_size;
    
    printf("mmap()-ed %ld bytes (%s)\n", result.size, path);
    
    close(fd);
    
    return(result);
}

static void
print_sourcepoint(struct mi_process proc, struct mi_sourcepoint *sp)
{
    // NOTE: sourcepoint file indices are 1-based
    if (proc.source_files[sp->file - 1].data == 0) {
        char *filename = proc.source_file_names[sp->file - 1];
        char *dir = proc.debug.comp_dir;
        
        char full_path[512] = { 0 };
        snprintf(full_path, 511, "%s/%s", dir, filename);
        
        struct mi_buffer file = read_file_mmap(full_path);
        proc.source_files[sp->file - 1] = file;
    }
    
    struct mi_buffer file = proc.source_files[sp->file - 1];
    
    char *source = (char *) file.data;
    u64 size = file.size;
    int current_line = 1;
    
    for (u32 i = 0; i < size; ++i) {
        if (current_line == sp->line) {
            int len = 0;
            int start = 0;
            int leading = 1;
            
            for (u32 j = i; j < size; ++j) {
                if (leading && (source[j] == '\t' || source[j] == ' ')) {
                    ++start;
                } else {
                    leading = 0;
                }
                
                if (source[j] == '\n') {
                    break;
                }
                
                ++len;
            }
            
            
            printf("%.*s\n", len - start, source + i + start);
            return;
        }
        
        if (source[i] == '\n') {
            current_line++;
        }
    }
}

static struct mi_process
process_create(char *path)
{
    struct mi_process result = { 0 };
    
    /* disable ASLR */
    syscall(SYS_personality, ADDR_NO_RANDOMIZE);
    
    pid_t pid = fork();
    
    if (pid == -1) {
        DIE("fork error\n");
    }
    
    if (pid == 0) {
        int rt = ptrace(PTRACE_TRACEME, 0, 0, 0);
        assert(rt == 0);
        char *args[] = { path, NULL };
        rt = execvp(path, args);
        if (rt == -1) {
            DIE("exevp error\n");
        }
    }
    
    struct mi_buffer file = read_file_mmap(path);
    
    result.elf = file.data;
    result.elf_size = file.size;
    result.pid = pid;
    
    return(result);
}

static struct mi_registers
get_process_registers(struct mi_process proc)
{
    struct user_regs_struct regs = { 0 };
    struct iovec iov = { &regs, sizeof(regs) };
    struct mi_registers result = { 0 };
    
    ptrace(PTRACE_GETREGSET, proc.pid, NT_PRSTATUS, &iov);
    
    result.rax = regs.rax;
    result.rip = regs.rip;
    result.rbp = regs.rbp;
    result.rbx = regs.rbx;
    result.rcx = regs.rcx;
    result.rdx = regs.rdx;
    result.rsi = regs.rsi;
    result.rdi = regs.rdi;
    result.rsp = regs.rsp;
    
    result._sys = regs;
    
    return(result);
}

static void
set_process_registers(struct mi_process proc, struct mi_registers regs)
{
    struct iovec iov = { &regs._sys, sizeof(regs._sys) };
    ptrace(PTRACE_GETREGSET, proc.pid, NT_PRSTATUS, &iov);
}

static void
print_current_instruction(struct mi_process proc)
{
    struct mi_registers regs = get_process_registers(proc);
    
    long wordb = ptrace(PTRACE_PEEKDATA, proc.pid, regs.rip - 4, NULL);
    long word = ptrace(PTRACE_PEEKDATA, proc.pid, regs.rip, NULL);
    long worda = ptrace(PTRACE_PEEKDATA, proc.pid, regs.rip + 4, NULL);
    
    u8 nb[12];
    memcpy(nb, &wordb, 4);
    memcpy(nb + 4, &word, 4);
    memcpy(nb + 8, &worda, 4);
    
    printf("PC = %#018lx: %x %x %x %x [%x] %x %x %x %x %x %x %x\n", regs.rip, 
           nb[0], nb[1], nb[2], nb[3], nb[4], nb[5], nb[6], nb[7],
           nb[8], nb[9], nb[10], nb[11]);
}