core-agent-linux/qubes-rpc/qopen-in-vm.c

#define _GNU_SOURCE
#include <dirent.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <signal.h>
#include <fcntl.h>
#include <malloc.h>
#include <stdlib.h>
#include <libqubes-rpc-filecopy.h>
#include <unistd.h>
#include <getopt.h>
#include <gui-fatal.h>
#include "dvm2.h"

void send_file(const char *fname, int view_only)
{
    const char *base;
    char sendbuf[DVM_FILENAME_SIZE] = {0};
    size_t sendbuf_size = DVM_FILENAME_SIZE;
    int fd = open(fname, O_RDONLY);
    if (fd < 0)
        gui_fatal("open %s", fname);

    _Static_assert(DVM_FILENAME_SIZE > sizeof(DVM_VIEW_ONLY_PREFIX),
            "DVM_FILENAME_SIZE > sizeof(DVM_VIEW_ONLY_PREFIX)");

    if (view_only) {
        strncpy(sendbuf, DVM_VIEW_ONLY_PREFIX, sendbuf_size);
        sendbuf_size -= strlen(DVM_VIEW_ONLY_PREFIX);
    }
    base = rindex(fname, '/');
    if (!base)
        base = fname;
    else
        base++;
    if (strlen(base) >= sendbuf_size)
        base += strlen(base) - sendbuf_size + 1;
    strncat(sendbuf,base,sendbuf_size - 1); /* fills out with NULs */
    sendbuf[DVM_FILENAME_SIZE - 1] = '\0';
    if (!write_all(1, sendbuf, DVM_FILENAME_SIZE))
        gui_fatal("send filename to dispVM");
    if (!copy_fd_all(1, fd))
        gui_fatal("send file to dispVM");
    close(1);
    close(fd);
}

int copy_and_return_nonemptiness(int tmpfd)
{
    struct stat st;
    if (!copy_fd_all(tmpfd, 0))
        gui_fatal("receiving file from dispVM");
    if (fstat(tmpfd, &st))
        gui_fatal("fstat");
    close(tmpfd);

    return st.st_size > 0;
}

void recv_file_nowrite(const char *fname)
{
    char *tempfile;
    char *errmsg;
    int tmpfd = -1;

    if (asprintf(&tempfile, "/tmp/file_edited_in_dvm.XXXXXX") != -1)
        tmpfd = mkstemp(tempfile);
    if (tmpfd < 0)
        gui_fatal("unable to create any temporary file, aborting");
    if (!copy_and_return_nonemptiness(tmpfd)) {
        unlink(tempfile);
        return;
    }
    if (asprintf(&errmsg,
         "The file %s has been edited in Disposable VM and the modified content has been received, "
         "but this file is in nonwritable directory and thus cannot be modified safely. The edited file has been "
         "saved to %s", fname, tempfile) != -1)
        gui_nonfatal(errmsg);
}

void actually_recv_file(const char *fname, const char *tempfile, int tmpfd)
{
    if (!copy_and_return_nonemptiness(tmpfd)) {
        unlink(tempfile);
        return;
    }
    if (rename(tempfile, fname))
        gui_fatal("rename");
}

void recv_file(const char *fname)
{
    int tmpfd = -1;
    char *tempfile;
    if (asprintf(&tempfile, "%s.XXXXXX", fname) != -1) {
        tmpfd = mkstemp(tempfile);
    }
    if (tmpfd < 0)
        recv_file_nowrite(fname);
    else
        actually_recv_file(fname, tempfile, tmpfd);
}

int main(int argc, char ** argv)
{
    char *fname;
    int view_only = 0;
    int ret;
    const struct option opts[] = {
        {"view-only", no_argument, &view_only, 1},
        {0}
    };

    while ((ret=getopt_long(argc, argv, "", opts, NULL)) != -1) {
        if (ret == '?') {
            exit(2);
        }
    }

    signal(SIGPIPE, SIG_IGN);

    if (optind >= argc)
        gui_fatal("OpenInVM - no file given?");
    fname = argv[optind];
    send_file(fname, view_only);
    if (!view_only) {
        recv_file(fname);
    } else {
        /* discard received data */
        int null_fd = open("/dev/null", O_WRONLY);
        copy_fd_all(null_fd, 0);
        close(null_fd);
    }
    return 0;
}