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156 lines (130 sloc) 4.252 kb
#include <sys/types.h>
#include <dirent.h>
#include <sys/syscall.h>
#include <sys/mman.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <sys/ioctl.h>
#include "ptrace.h"
extern void debug(const char *msg, ...);
static void do_unmap(struct ptrace_child *child, child_addr_t addr, int pages) {
if (addr == (unsigned long)-1)
return;
ptrace_remote_syscall(child, __NR_munmap, addr, pages, 0, 0, 0, 0);
}
int *get_child_tty_fds(struct ptrace_child *child, int *count) {
char buf[PATH_MAX];
char child_tty[PATH_MAX];
int n = 0, allocated = 0;
int *fds = NULL;
DIR *dir;
ssize_t len;
struct dirent *d;
debug("Looking up fds for tty in child.");
snprintf(buf, sizeof buf, "/proc/%d/fd/0", child->pid);
len = readlink(buf, child_tty, PATH_MAX);
if(len < 0)
return NULL;
child_tty[len] = 0;
debug("Resolved child tty: %s", child_tty);
snprintf(buf, sizeof buf, "/proc/%d/fd/", child->pid);
if ((dir = opendir(buf)) == NULL)
return NULL;
while ((d = readdir(dir)) != NULL) {
if (d->d_name[0] == '.') continue;
snprintf(buf, sizeof buf, "/proc/%d/fd/%s", child->pid, d->d_name);
len = readlink(buf, buf, PATH_MAX);
if (len < 0)
continue;
buf[len] = 0;
if (strcmp(buf, child_tty) == 0) {
if (n == allocated) {
allocated = allocated ? 2 * allocated : 2;
fds = realloc(fds, allocated);
if (!fds)
goto out;
}
debug("Found an alias for the tty: %s", d->d_name);
fds[n++] = atoi(d->d_name);
}
}
out:
*count = n;
closedir(dir);
return fds;
}
int attach_child(pid_t pid, const char *pty) {
struct ptrace_child child;
unsigned long scratch_page = -1;
int *child_tty_fds = NULL, n_fds, child_fd;
int i;
int err = 0;
if (ptrace_attach_child(&child, pid))
return errno;
if (ptrace_advance_to_state(&child, ptrace_at_syscall)) {
err = errno;
goto out_detach;
}
if (ptrace_save_regs(&child)) {
err = errno;
goto out_detach;
}
scratch_page = ptrace_remote_syscall(&child, mmap_syscall, 0,
PAGE_SIZE, PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE, 0, 0);
if (scratch_page > (unsigned long)-100) {
err = scratch_page;
goto out_unmap;
}
debug("Allocated scratch page: %lx", scratch_page);
child_tty_fds = get_child_tty_fds(&child, &n_fds);
if (!child_tty_fds) {
err = -1;
goto out_unmap;
}
if (ptrace_memcpy_to_child(&child, scratch_page, pty, strlen(pty)+1)) {
err = errno;
goto out_free_fds;
}
child_fd = ptrace_remote_syscall(&child, __NR_open,
scratch_page, O_RDWR|O_NOCTTY,
0, 0, 0, 0);
if (child_fd < 0) {
err = child_fd;
goto out_free_fds;
}
debug("Opened the new tty in the child: %d", child_fd);
err = ptrace_remote_syscall(&child, __NR_ioctl,
child_tty_fds[0], TCGETS, scratch_page,
0, 0, 0);
debug("TCGETS(%d): %d", child_tty_fds[0], err);
if(err < 0)
goto out_close;
err = ptrace_remote_syscall(&child, __NR_ioctl,
child_fd, TCSETS, scratch_page,
0, 0, 0);
debug("TCSETS: %d", err);
if (err < 0)
goto out_close;
debug("Copied terminal settings");
for (i = 0; i < n_fds; i++)
ptrace_remote_syscall(&child, __NR_dup2,
child_fd, child_tty_fds[i],
0, 0, 0, 0);
err = 0;
out_close:
ptrace_remote_syscall(&child, __NR_close, child_fd,
0, 0, 0, 0, 0);
out_free_fds:
free(child_tty_fds);
out_unmap:
do_unmap(&child, scratch_page, 1);
ptrace_restore_regs(&child);
out_detach:
ptrace_detach_child(&child);
return err;
}
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