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readv-writev.c
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readv-writev.c
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#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/uio.h>
#define MANA_ADDR 0x601044
typedef struct iovec iovec_t;
// man process_vm_readv
// These system calls were added in Linux 3.2.
// Support is provided in glibc since version 2.15.
ssize_t remote_read_bytes(pid_t pid, void *local_addr, void *remote_addr, size_t len)
{
iovec_t local_iov = {local_addr, len};
iovec_t remote_iov = {remote_addr, len};
return process_vm_readv(pid, &local_iov, 1, &remote_iov, 1, 0);
}
ssize_t remote_write_bytes(pid_t pid, void *local_addr, void *remote_addr, size_t len)
{
iovec_t local_iov = {local_addr, len};
iovec_t remote_iov = {remote_addr, len};
return process_vm_writev(pid, &local_iov, 1, &remote_iov, 1, 0);
}
ssize_t remote_read32(pid_t pid, void *local_addr, void *remote_addr)
{
return remote_read_bytes(pid, local_addr, remote_addr, 4);
}
ssize_t remote_write32(pid_t pid, void *local_addr, void *remote_addr)
{
return remote_write_bytes(pid, local_addr, remote_addr, 4);
}
int main(int argc, char **argv)
{
if (argc != 2) {
printf("usage:\nreadv-writev %%u <pid>\n");
return 1;
}
// Entrada do usuário não é verificada
pid_t pid = strtol(argv[1], 0, 10);
unsigned int current_mana;
ssize_t bytes_read = remote_read32(pid, ¤t_mana, (void *) MANA_ADDR);
if (bytes_read != sizeof current_mana) {
fprintf(stderr, "%s\n", strerror(errno));
return 2;
}
current_mana += 301;
ssize_t bytes_written = remote_write32(pid, ¤t_mana, (void *) MANA_ADDR);
if (bytes_written != sizeof current_mana) {
fprintf(stderr, "%s\n", strerror(errno));
return 3;
}
printf("Done!\n");
return 0;
}