267 lines
9.6 KiB
C
267 lines
9.6 KiB
C
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/*
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* main.c
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*
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* the command line user interface
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*/
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#define _GNU_SOURCE
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#include <unistd.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <getopt.h>
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#include <linux/limits.h>
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#include <stdbool.h>
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#include <sys/stat.h>
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#include <sys/xattr.h>
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#include <errno.h>
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#ifndef _SYS_STAT_H
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#include <linux/stat.h>
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#endif
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#include "logic.h"
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#include "sh.h"
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#define STRING_BUFFER_SIZE PATH_MAX * 2
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// currently, brief and verbose are mutually exclusive
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bool verbose;
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bool brief;
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bool yes;
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void print_help(const char *program) {
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printf("Usage: %s command options\n", program);
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puts("");
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puts("Commands:");
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puts(" vacuum - remove duplicated files in upperdir where copy_up is done but the file is not actually modified");
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puts(" diff - show the list of actually changed files");
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puts(" merge - merge all changes from upperdir to lowerdir, and clear upperdir");
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puts(" deref - copy changes from upperdir to a new upperdir unfolding redirect and metacopy");
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puts("");
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puts("Options:");
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puts(" -l, --lowerdir=LOWERDIR the lowerdir of OverlayFS (required)");
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puts(" -u, --upperdir=UPPERDIR the upperdir of OverlayFS (required)");
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puts(" -m, --mountdir=MOUNTDIR the mountdir of OverlayFS (optional)");
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puts(" -L, --lowernew=LOWERNEW the lowerdir of new OverlayFS (optional)");
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puts(" -U, --uppernew=UPPERNEW the upperdir of new OverlayFS (optional)");
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puts(" -y --yes don't prompt if OverlayFS is still mounted (optional)");
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puts(" -v, --verbose with diff action only: when a directory only exists in one version, still list every file of the directory");
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puts(" -b, --brief with diff action only: conform to output of diff --brief --recursive --no-dereference");
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puts(" -h, --help show this help text");
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puts("");
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puts("See https://github.com/kmxz/overlayfs-tools/ for warnings and more information.");
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}
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bool starts_with(const char *haystack, const char* needle) {
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return strncmp(needle, haystack, strlen(needle)) == 0;
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}
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bool is_mounted(const char *lower, const char *upper) {
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FILE *f = fopen("/proc/mounts", "r");
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if (!f) {
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fprintf(stderr, "Cannot read /proc/mounts to test whether OverlayFS is mounted.\n");
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return true;
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}
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char buf[STRING_BUFFER_SIZE];
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while (fgets(buf, STRING_BUFFER_SIZE, f)) {
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if (!starts_with(buf, "overlay")) {
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continue;
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}
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if (strlen(buf) == STRING_BUFFER_SIZE) {
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fprintf(stderr, "OverlayFS line in /proc/mounts is too long.\n");
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return true;
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}
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char *m_lower = strstr(buf, "lowerdir=");
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char *m_upper = strstr(buf, "upperdir=");
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if (m_lower == NULL || m_upper == NULL) {
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fprintf(stderr, "Cannot extract information from OverlayFS line in /proc/mounts.\n");
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return true;
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}
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m_lower = &(m_lower[strlen("lowerdir=")]);
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m_upper = &(m_upper[strlen("upperdir=")]);
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if (!(strncmp(lower, m_lower, strlen(lower)) && strncmp(upper, m_upper, strlen(upper)))) {
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printf("The OverlayFS involved is still mounted.\n");
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return true;
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}
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}
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return false;
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}
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bool check_mounted(const char *lower, const char *upper) {
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if (is_mounted(lower, upper) && !yes) {
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printf("It is strongly recommended to unmount OverlayFS first. Still continue (not recommended)?: \n");
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int r = getchar();
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if (r != 'Y' && r != 'y') {
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return true;
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}
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}
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return false;
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}
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bool directory_exists(const char *path) {
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struct stat sb;
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if (lstat(path, &sb) != 0) { return false; }
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return (sb.st_mode & S_IFMT) == S_IFDIR;
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}
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bool directory_create(const char *name, const char *path) {
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if (mkdir(path, 0755) == 0 || errno == EEXIST) { return true; }
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fprintf(stderr, "%s directory '%s' does not exist and cannot be created.\n", name, path);
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exit(EXIT_FAILURE);
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}
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bool real_check_xattr_trusted(const char *tmp_path, int tmp_file) {
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int ret = fsetxattr(tmp_file, "trusted.overlay.test", "naive", 5, 0);
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close(tmp_file);
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if (ret) { return false; }
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char verify_buffer[10];
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if (getxattr(tmp_path, "trusted.overlay.test", verify_buffer, 10) != 5) { return false; }
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return !strncmp(verify_buffer, "naive", 5);
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}
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bool check_xattr_trusted(const char *upper) {
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char tmp_path[PATH_MAX];
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strcpy(tmp_path, upper);
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strcat(tmp_path, "/.xattr_test_XXXXXX.tmp");
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int tmp_file = mkstemps(tmp_path, 4);
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if (tmp_file < 0) { return false; }
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bool ret = real_check_xattr_trusted(tmp_path, tmp_file);
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unlink(tmp_path);
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return ret;
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}
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int main(int argc, char *argv[]) {
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char *lower = NULL;
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char *upper = NULL;
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char *dir, *mnt = NULL;
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static struct option long_options[] = {
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{ "lowerdir", required_argument, 0, 'l' },
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{ "upperdir", required_argument, 0, 'u' },
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{ "mountdir", required_argument, 0, 'm' },
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{ "lowernew", required_argument, 0, 'L' },
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{ "uppernew", required_argument, 0, 'U' },
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{ "yes", no_argument , 0, 'y' },
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{ "help", no_argument , 0, 'h' },
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{ "verbose", no_argument , 0, 'v' },
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{ "brief", no_argument , 0, 'b' },
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{ 0, 0, 0, 0 }
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};
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int opt = 0;
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int long_index = 0;
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while ((opt = getopt_long_only(argc, argv, "l:u:m:L:U:yhvb", long_options, &long_index)) != -1) {
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switch (opt) {
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case 'l':
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lower = realpath(optarg, NULL);
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if (lower) { vars[LOWERDIR] = lower; }
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break;
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case 'u':
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upper = realpath(optarg, NULL);
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if (upper) { vars[UPPERDIR] = upper; }
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break;
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case 'm':
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mnt = realpath(optarg, NULL);
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if (mnt) { vars[MOUNTDIR] = mnt; }
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break;
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case 'L':
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directory_create("New lowerdir", optarg);
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dir = realpath(optarg, NULL);
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if (dir) { vars[LOWERNEW] = dir; }
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break;
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case 'U':
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directory_create("New upperdir", optarg);
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dir = realpath(optarg, NULL);
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if (dir) { vars[UPPERNEW] = dir; }
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break;
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case 'y':
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yes = true;
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break;
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case 'h':
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print_help(argv[0]);
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return EXIT_SUCCESS;
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case 'v':
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verbose = true;
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brief = false;
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break;
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case 'b':
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verbose = false;
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brief = true;
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break;
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default:
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fprintf(stderr, "Option %c is not supported.\n", opt);
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goto see_help;
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}
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}
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if (!lower) {
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fprintf(stderr, "Lower directory not specified.\n");
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goto see_help;
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}
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if (!directory_exists(lower)) {
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fprintf(stderr, "Lower directory cannot be opened.\n");
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goto see_help;
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}
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if (!upper) {
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fprintf(stderr, "Upper directory not specified.\n");
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goto see_help;
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}
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if (!directory_exists(upper)) {
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fprintf(stderr, "Upper directory cannot be opened.\n");
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goto see_help;
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}
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if (!check_xattr_trusted(upper)) {
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fprintf(stderr, "The program cannot write trusted.* xattr. Try run again as root.\n");
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return EXIT_FAILURE;
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}
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// Relax check for mounted overlay if we are not going to modify lowerdir/upperdir
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if ((!vars[LOWERNEW] || !vars[UPPERNEW]) && check_mounted(lower, upper)) {
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return EXIT_FAILURE;
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}
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if (optind == argc - 1) {
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int out;
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char filename_template[] = "overlay-tools-XXXXXX.sh";
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FILE *script = NULL;
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if (strcmp(argv[optind], "diff") == 0) {
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out = diff(lower, upper);
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} else if (strcmp(argv[optind], "vacuum") == 0) {
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script = create_shell_script(filename_template);
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if (script == NULL) { fprintf(stderr, "Script file cannot be created.\n"); return EXIT_FAILURE; }
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out = vacuum(lower, upper, script);
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} else if (strcmp(argv[optind], "merge") == 0) {
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script = create_shell_script(filename_template);
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if (script == NULL) { fprintf(stderr, "Script file cannot be created.\n"); return EXIT_FAILURE; }
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out = merge(lower, upper, script);
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} else if (strcmp(argv[optind], "deref") == 0) {
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if (!mnt || !vars[UPPERNEW]) { fprintf(stderr, "'deref' command requires --uppernew and --mountdir.\n"); return EXIT_FAILURE; }
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if (!directory_exists(mnt)) {
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fprintf(stderr, "OverlayFS mount directory cannot be opened.\n");
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goto see_help;
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}
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script = create_shell_script(filename_template);
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if (script == NULL) { fprintf(stderr, "Script file cannot be created.\n"); return EXIT_FAILURE; }
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out = deref(mnt, upper, script);
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} else {
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fprintf(stderr, "Action not supported.\n");
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goto see_help;
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}
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if (script != NULL) {
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printf("The script %s is created. Run the script to do the actual work please. Remember to run it when the OverlayFS is not mounted.\n", filename_template);
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fclose(script);
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}
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if (out) {
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fprintf(stderr, "Action aborted due to fatal error.\n");
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return EXIT_FAILURE;
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}
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return EXIT_SUCCESS;
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}
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fprintf(stderr, "Please specify one action.\n");
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see_help:
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fprintf(stderr, "Try '%s --help' for more information.\n", argv[0]);
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return EXIT_FAILURE;
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}
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