/*
* list_installable_bundles()
* Parse the full manifest for the current version of the OS and print
* all available bundles.
*/
int list_installable_bundles()
{
struct list *list;
struct file *file;
struct manifest *MoM = NULL;
int current_version;
int lock_fd;
int ret;
if (!init_globals()) {
return EINIT_GLOBALS;
}
current_version = read_version_from_subvol_file(path_prefix);
if (swupd_init(&lock_fd) != 0) {
printf("Error: Failed updater initialization. Exiting now\n");
return ECURL_INIT;
}
ret = create_required_dirs();
if (ret != 0) {
printf("State directory %s cannot be recreated, aborting removal\n", STATE_DIR);
v_lockfile(lock_fd);
return EXIT_FAILURE;
}
get_mounted_directories();
if (!check_network()) {
printf("Error: Network issue, unable to download manifest\n");
v_lockfile(lock_fd);
return EXIT_FAILURE;
}
swupd_curl_set_current_version(current_version);
ret = load_manifests(current_version, current_version, "MoM", NULL, &MoM);
if (ret != 0) {
v_lockfile(lock_fd);
return ret;
}
list = MoM->manifests;
while (list) {
file = list->data;
list = list->next;
printf("%s\n", file->filename);
}
free_manifest(MoM);
v_lockfile(lock_fd);
return 0;
}
/* this function is intended to encapsulate the basic swupd
* initializations for the majority of commands, that is:
* - Make sure root is the user running the code
* - Initialize log facility
* - Get the lock
* - initialize mounted directories
* - Initialize curl
*/
int swupd_init(int *lock_fd)
{
int ret = 0;
check_root();
*lock_fd = p_lockfile();
if (*lock_fd < 0) {
ret = ELOCK_FILE;
goto out_fds;
}
get_mounted_directories();
if (swupd_curl_init() != 0) {
ret = ECURL_INIT;
goto out_close_lock;
}
return ret;
out_close_lock:
v_lockfile(*lock_fd);
out_fds:
dump_file_descriptor_leaks();
return ret;
}
/*
* list_installable_bundles()
* Parse the full manifest for the current version of the OS and print
* all available bundles.
*/
int list_installable_bundles()
{
struct list *list;
struct file *file;
struct manifest *MoM = NULL;
int current_version;
int lock_fd;
int ret;
ret = swupd_init(&lock_fd);
if (ret != 0) {
printf("Error: Failed updater initialization. Exiting now\n");
return ret;
}
if (!check_network()) {
printf("Error: Network issue, unable to download manifest\n");
v_lockfile(lock_fd);
return EXIT_FAILURE;
}
current_version = get_current_version(path_prefix);
if (current_version < 0) {
printf("Error: Unable to determine current OS version\n");
v_lockfile(lock_fd);
return ECURRENT_VERSION;
}
swupd_curl_set_current_version(current_version);
MoM = load_mom(current_version);
if (!MoM) {
v_lockfile(lock_fd);
return ret;
}
list = MoM->manifests;
while (list) {
file = list->data;
list = list->next;
printf("%s\n", file->filename);
}
free_manifest(MoM);
v_lockfile(lock_fd);
return 0;
}
void swupd_deinit(void)
{
terminate_signature();
swupd_curl_deinit();
free_globals();
v_lockfile();
dump_file_descriptor_leaks();
}
void swupd_deinit(int lock_fd)
{
terminate_signature();
swupd_curl_cleanup();
free_subscriptions();
free_globals();
v_lockfile(lock_fd);
dump_file_descriptor_leaks();
}
int search_main(int argc, char **argv)
{
int ret = 0;
int lock_fd = 0;
struct manifest *MoM = NULL;
if (!parse_options(argc, argv)) {
return EXIT_FAILURE;
}
ret = swupd_init(&lock_fd);
if (ret != 0) {
printf("Failed swupd initialization, exiting now.\n");
goto clean_exit;
}
if (!check_network()) {
printf("Error: Network issue, unable to proceed with update\n");
ret = EXIT_FAILURE;
goto clean_exit;
}
if (!init) {
printf("Searching for '%s'\n\n", search_string);
}
ret = download_manifests(&MoM);
if (ret != 0) {
printf("Error: Failed to download manifests\n");
goto clean_exit;
}
if (init) {
printf("Successfully retreived manifests. Exiting\n");
ret = 0;
goto clean_exit;
}
/* Arbitrary upper limit to ensure we aren't getting handed garbage */
if (!display_files &&
((strlen(search_string) <= 0) || (strlen(search_string) > NAME_MAX))) {
printf("Error - search string invalid\n");
ret = EXIT_FAILURE;
goto clean_exit;
}
do_search(MoM, search_type, search_string);
clean_exit:
free_manifest(MoM);
free_globals();
swupd_curl_cleanup();
v_lockfile(lock_fd);
return ret;
}
/*
* list_installable_bundles()
* Parse the full manifest for the current version of the OS and print
* all available bundles.
*/
int list_installable_bundles()
{
struct list *list;
struct file *file;
struct manifest *MoM = NULL;
int current_version;
int lock_fd;
int ret;
ret = swupd_init(&lock_fd);
if (ret != 0) {
printf("Error: Failed updater initialization. Exiting now\n");
return ret;
}
if (!check_network()) {
printf("Error: Network issue, unable to download manifest\n");
v_lockfile(lock_fd);
return EXIT_FAILURE;
}
current_version = read_version_from_subvol_file(path_prefix);
swupd_curl_set_current_version(current_version);
ret = load_manifests(current_version, current_version, "MoM", NULL, &MoM);
if (ret != 0) {
v_lockfile(lock_fd);
return ret;
}
list = MoM->manifests;
while (list) {
file = list->data;
list = list->next;
printf("%s\n", file->filename);
}
free_manifest(MoM);
v_lockfile(lock_fd);
return 0;
}
/* this function is intended to encapsulate the basic swupd
* initializations for the majority of commands, that is:
* - Make sure root is the user running the code
* - Initialize globals
* - initialize mounted directories
* - Create necessary directories
* - Get the lock
* - Initialize curl
* - Initialize signature checking
*/
int swupd_init(void)
{
int ret = 0;
check_root();
record_fds();
/* Check that our system time is reasonably valid before continuing,
* or the certificate verification will fail with invalid time */
if (timecheck) {
if (!verify_time()) {
ret = EBADTIME;
goto out_fds;
}
}
if (!init_globals()) {
ret = EINIT_GLOBALS;
goto out_fds;
}
get_mounted_directories();
if (create_required_dirs()) {
ret = EREQUIRED_DIRS;
goto out_fds;
}
if (p_lockfile() < 0) {
ret = ELOCK_FILE;
goto out_fds;
}
if (swupd_curl_init() != 0) {
ret = ECURL_INIT;
goto out_close_lock;
}
/* If --nosigcheck, we do not attempt any signature checking */
if (sigcheck && !initialize_signature()) {
ret = ESIGNATURE;
terminate_signature();
goto out_close_lock;
}
return ret;
out_close_lock:
v_lockfile();
out_fds:
dump_file_descriptor_leaks();
return ret;
}
/* this function is intended to encapsulate the basic swupd
* initializations for the majority of commands, that is:
* - Make sure root is the user running the code
* - Initialize log facility
* - Get the lock
* - initialize mounted directories
* - Initialize curl
*/
int swupd_init(int *lock_fd)
{
int ret = 0;
check_root();
if (!init_globals()) {
ret = EINIT_GLOBALS;
goto out_fds;
}
get_mounted_directories();
if (create_required_dirs()) {
ret = EREQUIRED_DIRS;
goto out_fds;
}
*lock_fd = p_lockfile();
if (*lock_fd < 0) {
ret = ELOCK_FILE;
goto out_fds;
}
if (swupd_curl_init() != 0) {
ret = ECURL_INIT;
goto out_close_lock;
}
if (!initialize_signature()) {
ret = ESIGNATURE;
terminate_signature();
goto out_close_lock;
}
return ret;
out_close_lock:
v_lockfile(*lock_fd);
out_fds:
dump_file_descriptor_leaks();
return ret;
}
/* Bundle install one ore more bundles passed in bundles
* param as a null terminated array of strings
*/
int install_bundles_frontend(char **bundles)
{
int lock_fd;
int ret = 0;
int current_version;
struct list *bundles_list = NULL;
struct manifest *mom;
/* initialize swupd and get current version from OS */
ret = swupd_init(&lock_fd);
if (ret != 0) {
printf("Failed updater initialization, exiting now.\n");
return ret;
}
current_version = read_version_from_subvol_file(path_prefix);
swupd_curl_set_current_version(current_version);
ret = load_manifests(current_version, current_version, "MoM", NULL, &mom);
if (ret != 0) {
printf("Cannot load official manifest MoM for version %i\n", current_version);
ret = EMOM_NOTFOUND;
goto clean_and_exit;
}
for (; *bundles; ++bundles) {
bundles_list = list_prepend_data(bundles_list, *bundles);
}
ret = install_bundles(bundles_list, current_version, mom);
list_free_list(bundles_list);
free_manifest(mom);
clean_and_exit:
swupd_curl_cleanup();
v_lockfile(lock_fd);
dump_file_descriptor_leaks();
free_globals();
return ret;
}
/* Bundle install one ore more bundles passed in bundles
* param as a null terminated array of strings
*/
int install_bundles(char **bundles)
{
int lock_fd;
int ret = 0;
int current_version;
struct manifest *mom;
struct list *iter;
struct sub *sub;
struct file *file;
/* step 1: initialize swupd and get current version from OS */
if (!init_globals()) {
return EINIT_GLOBALS;
}
ret = swupd_init(&lock_fd);
if (ret != 0) {
printf("Failed updater initialization, exiting now.\n");
return ret;
}
current_version = read_version_from_subvol_file(path_prefix);
swupd_curl_set_current_version(current_version);
/* first of all, make sure STATE_DIR is there, recreate if necessary*/
ret = create_required_dirs();
if (ret != 0) {
printf("State directory %s cannot be recreated, aborting installation\n", STATE_DIR);
goto clean_and_exit;
}
ret = load_manifests(current_version, current_version, "MoM", NULL, &mom);
if (ret != 0) {
printf("Cannot load official manifest MoM for version %i\n", current_version);
ret = EMOM_NOTFOUND;
goto clean_and_exit;
}
/* step 2: check bundle args are valid if so populate subs struct */
int i;
for (i = 0; *bundles; ++bundles) {
if (is_tracked_bundle(*bundles)) {
printf("%s bundle already installed, skipping it\n", *bundles);
continue;
}
if (!manifest_has_component(mom, *bundles)) {
printf("%s bundle name is invalid, skipping it...\n", *bundles);
continue;
}
if (component_subscribed(*bundles)) {
continue;
}
create_and_append_subscription(*bundles);
i++;
printf("Added bundle %s for installation\n", *bundles);
}
if (i == 0) {
printf("There are no pending bundles to install, exiting now\n");
ret = EBUNDLE_INSTALL;
goto clean_manifest_and_exit;
}
subscription_versions_from_MoM(mom, 0);
recurse_manifest(mom, NULL);
consolidate_submanifests(mom);
/* step 3: download neccessary packs */
ret = rm_staging_dir_contents("download");
printf("Downloading required packs...\n");
ret = download_subscribed_packs(0, current_version, true);
if (ret != 0) {
printf("pack downloads failed, cannot proceed with the installation, exiting.\n");
goto clean_subs_and_exit;
}
/* step 4: Install all bundle(s) files into the fs */
printf("Installing bundle(s) files...\n");
iter = list_head(mom->files);
while (iter) {
file = iter->data;
iter = iter->next;
if (file->is_deleted || file->do_not_update || ignore(file)) {
continue;
}
ret = do_staging(file);
if (ret == 0) {
rename_staged_file_to_final(file);
}
}
sync();
/* step 5: create bundle(s) subscription entries to track them
*
* Strictly speaking each manifest has an entry to write its own bundle filename
* and thus tracking automagically, here just making sure.
*/
iter = list_head(subs);
while (iter) {
sub = iter->data;
iter = iter->next;
printf("Tracking %s bundle on the system\n", sub->component);
ret = track_bundle_in_system(sub->component);
if (ret != 0) {
printf("Cannot track %s bundle on the system\n", sub->component);
}
}
/* Run any scripts that are needed to complete update */
run_scripts();
ret = 0;
printf("Bundle(s) installation done.\n");
clean_subs_and_exit:
free_subscriptions();
clean_manifest_and_exit:
free_manifest(mom);
clean_and_exit:
swupd_curl_cleanup();
v_lockfile(lock_fd);
dump_file_descriptor_leaks();
free_globals();
return ret;
}
/* This function is a fresh new implementation for a bundle
* remove without being tied to verify loop, this means
* improved speed and space as well as more roubustness and
* flexibility. What it does is basically:
*
* 1) Read MoM and load all submanifests except the one to be
* removed and then consolidate them.
* 2) Load the removed bundle submanifest.
* 3) Order the file list by filename
* 4) Deduplicate removed submanifest file list that happens
* to be on the MoM (minus bundle to be removed).
* 5) iterate over to be removed bundle submanifest file list
* performing a unlink(2) for each filename.
* 6) Done.
*/
int remove_bundle(const char *bundle_name)
{
int lock_fd;
int ret = 0;
int current_version = CURRENT_OS_VERSION;
struct manifest *current_mom, *bundle_manifest;
/* Initially we don't support format nor path_prefix
* for bundle_rm but eventually that will be added, then
* set_format_string() and init_globals() must be pulled out
* to the caller to properly initialize in case those opts
* passed to the command.
*/
set_format_string(NULL);
if (!init_globals()) {
return EINIT_GLOBALS;
}
ret = swupd_init(&lock_fd);
if (ret != 0) {
printf("Failed updater initialization, exiting now.\n");
return ret;
}
/* os-core bundle not allowed to be removed...
* although this is going to be caught later because of all files
* being marked as 'duplicated' and note removing anything
* anyways, better catch here and return success, no extra work to be done.
*/
if (strcmp(bundle_name, "os-core") == 0) {
ret = EBUNDLE_NOT_TRACKED;
goto out_free_curl;
}
if (!is_tracked_bundle(bundle_name)) {
ret = EBUNDLE_NOT_TRACKED;
goto out_free_curl;
}
current_version = read_version_from_subvol_file(path_prefix);
swupd_curl_set_current_version(current_version);
/* first of all, make sure STATE_DIR is there, recreate if necessary*/
ret = create_required_dirs();
if (ret != 0) {
printf("State directory %s cannot be recreated, aborting removal\n", STATE_DIR);
goto out_free_curl;
}
ret = load_manifests(current_version, current_version, "MoM", NULL, ¤t_mom);
if (ret != 0) {
goto out_free_curl;
}
/* load all tracked bundles into memory */
read_subscriptions_alt();
/* now popout the one to be removed */
ret = unload_tracked_bundle(bundle_name);
if (ret != 0) {
goto out_free_mom;
}
subscription_versions_from_MoM(current_mom, 0);
/* load all submanifest minus the one to be removed */
recurse_manifest(current_mom, NULL);
consolidate_submanifests(current_mom);
/* Now that we have the consolidated list of all files, load bundle to be removed submanifest*/
ret = load_bundle_manifest(bundle_name, current_version, &bundle_manifest);
if (ret != 0) {
goto out_free_mom;
}
/* deduplication needs file list sorted by filename, do so */
bundle_manifest->files = list_sort(bundle_manifest->files, file_sort_filename);
deduplicate_files_from_manifest(&bundle_manifest, current_mom);
printf("Deleting bundle files...\n");
remove_files_in_manifest_from_fs(bundle_manifest);
printf("Untracking bundle from system...\n");
rm_bundle_file(bundle_name);
printf("Success: Bundle removed\n");
free_manifest(bundle_manifest);
out_free_mom:
free_manifest(current_mom);
out_free_curl:
if (ret) {
printf("Error: Bundle remove failed\n");
}
swupd_curl_cleanup();
v_lockfile(lock_fd);
dump_file_descriptor_leaks();
return ret;
}
int main_update()
{
int current_version = -1, server_version = -1;
struct manifest *current_manifest = NULL, *server_manifest = NULL;
struct list *updates = NULL;
int ret;
int lock_fd;
int retries = 0;
int timeout = 10;
srand(time(NULL));
ret = swupd_init(&lock_fd);
if (ret != 0) {
/* being here means we already close log by a previously caught error */
printf("Updater failed to initialize, exiting now.\n");
return ret;
}
if (!check_network()) {
printf("Error: Network issue, unable to proceed with update\n");
ret = EXIT_FAILURE;
goto clean_curl;
}
printf("Update started.\n");
read_subscriptions_alt();
if (!signature_initialize(UPDATE_CA_CERTS_PATH "/" SIGNATURE_CA_CERT)) {
goto clean_curl;
}
/* Step 1: get versions */
ret = check_versions(¤t_version, &server_version, path_prefix);
if (ret < 0) {
goto clean_curl;
}
if (server_version <= current_version) {
printf("Version on server (%i) is not newer than system version (%i)\n", server_version, current_version);
ret = EXIT_SUCCESS;
goto clean_curl;
}
printf("Preparing to update from %i to %i\n", current_version, server_version);
/* Step 2: housekeeping */
if (rm_staging_dir_contents("download")) {
goto clean_curl;
}
load_current_manifests:
/* Step 3: setup manifests */
/* get the from/to MoM manifests */
printf("Querying current manifest.\n");
ret = load_manifests(current_version, current_version, "MoM", NULL, ¤t_manifest);
if (ret) {
/* TODO: possibly remove this as not getting a "from" manifest is not fatal
* - we just don't apply deltas */
if (retries < MAX_TRIES) {
increment_retries(&retries, &timeout);
printf("Retry #%d downloading from/to MoM Manifests\n", retries);
goto load_current_manifests;
}
printf("Failure retrieving manifest from server\n");
goto clean_exit;
}
/* Reset the retries and timeout for subsequent download calls */
retries = 0;
timeout = 10;
load_server_manifests:
printf("Querying server manifest.\n");
ret = load_manifests(current_version, server_version, "MoM", NULL, &server_manifest);
if (ret) {
if (retries < MAX_TRIES) {
increment_retries(&retries, &timeout);
printf("Retry #%d downloading server Manifests\n", retries);
goto load_server_manifests;
}
printf("Failure retrieving manifest from server\n");
goto clean_exit;
}
if (current_manifest == NULL || server_manifest == NULL) {
printf("Unable to load manifest after retrying (config or network problem?)\n");
goto clean_exit;
}
retries = 0;
timeout = 10;
ret = add_included_manifests(server_manifest);
if (ret) {
goto clean_exit;
}
subscription_versions_from_MoM(current_manifest, 1);
subscription_versions_from_MoM(server_manifest, 0);
link_submanifests(current_manifest, server_manifest);
/* updating subscribed manifests is done as part of recurse_manifest */
/* read the current collective of manifests that we are subscribed to */
current_manifest->submanifests = recurse_manifest(current_manifest, NULL);
if (!current_manifest->submanifests) {
printf("Cannot load current MoM sub-manifests, (%s), exiting\n", strerror(errno));
goto clean_exit;
}
/* consolidate the current collective manifests down into one in memory */
current_manifest->files = files_from_bundles(current_manifest->submanifests);
current_manifest->files = consolidate_files(current_manifest->files);
/* read the new collective of manifests that we are subscribed to */
server_manifest->submanifests = recurse_manifest(server_manifest, NULL);
if (!server_manifest->submanifests) {
printf("Error: Cannot load server MoM sub-manifests, (%s), exiting\n", strerror(errno));
goto clean_exit;
}
/* consolidate the new collective manifests down into one in memory */
server_manifest->files = files_from_bundles(server_manifest->submanifests);
server_manifest->files = consolidate_files(server_manifest->files);
/* prepare for an update process based on comparing two in memory manifests */
link_manifests(current_manifest, server_manifest);
#if 0
debug_write_manifest(current_manifest, "debug_manifest_current.txt");
debug_write_manifest(server_manifest, "debug_manifest_server.txt");
#endif
/* Step 4: check disk state before attempting update */
run_preupdate_scripts(server_manifest);
download_packs:
/* Step 5: get the packs and untar */
ret = download_subscribed_packs(false);
if (ret) {
// packs don't always exist, tolerate that but not ENONET
if (retries < MAX_TRIES) {
increment_retries(&retries, &timeout);
printf("Retry #%d downloading packs\n", retries);
goto download_packs;
}
printf("No network, or server unavailable for pack downloads\n");
goto clean_exit;
}
/* Step 6: some more housekeeping */
/* TODO: consider trying to do less sorting of manifests */
updates = create_update_list(current_manifest, server_manifest);
link_renames(updates, current_manifest); /* TODO: Have special lists for candidate and renames */
print_statistics(current_version, server_version);
/* Step 7: apply the update */
ret = update_loop(updates, server_manifest);
if (ret == 0) {
ret = update_device_latest_version(server_version);
printf("Update was applied.\n");
}
delete_motd();
/* Run any scripts that are needed to complete update */
run_scripts();
clean_exit:
list_free_list(updates);
free_manifest(current_manifest);
free_manifest(server_manifest);
clean_curl:
signature_terminate();
swupd_curl_cleanup();
free_subscriptions();
free_globals();
v_lockfile(lock_fd);
dump_file_descriptor_leaks();
if ((current_version < server_version) && (ret == 0)) {
printf("Update successful. System updated from version %d to version %d\n",
current_version, server_version);
} else if (ret == 0) {
printf("Update complete. System already up-to-date at version %d\n", current_version);
}
return ret;
}
static void clean_deinit(void)
{
free_globals();
v_lockfile();
}
/* This function is a fresh new implementation for a bundle
* remove without being tied to verify loop, this means
* improved speed and space as well as more roubustness and
* flexibility. What it does is basically:
*
* 1) Read MoM and load all submanifests except the one to be
* removed and then consolidate them.
* 2) Load the removed bundle submanifest.
* 3) Order the file list by filename
* 4) Deduplicate removed submanifest file list that happens
* to be on the MoM (minus bundle to be removed).
* 5) iterate over to be removed bundle submanifest file list
* performing a unlink(2) for each filename.
* 6) Done.
*/
int remove_bundle(const char *bundle_name)
{
int lock_fd;
int ret = 0;
int current_version = CURRENT_OS_VERSION;
struct manifest *current_mom, *bundle_manifest;
ret = swupd_init(&lock_fd);
if (ret != 0) {
printf("Failed updater initialization, exiting now.\n");
return ret;
}
/* os-core bundle not allowed to be removed...
* although this is going to be caught later because of all files
* being marked as 'duplicated' and note removing anything
* anyways, better catch here and return success, no extra work to be done.
*/
if (strcmp(bundle_name, "os-core") == 0) {
ret = EBUNDLE_NOT_TRACKED;
goto out_free_curl;
}
if (!is_tracked_bundle(bundle_name)) {
ret = EBUNDLE_NOT_TRACKED;
goto out_free_curl;
}
current_version = read_version_from_subvol_file(path_prefix);
swupd_curl_set_current_version(current_version);
ret = load_manifests(current_version, current_version, "MoM", NULL, ¤t_mom);
if (ret != 0) {
goto out_free_curl;
}
if (!search_bundle_in_manifest(current_mom, bundle_name)) {
printf("Bundle name is invalid, aborting removal\n");
ret = EBUNDLE_REMOVE;
goto out_free_mom;
}
/* load all tracked bundles into memory */
read_subscriptions_alt();
/* now popout the one to be removed */
ret = unload_tracked_bundle(bundle_name);
if (ret != 0) {
goto out_free_mom;
}
subscription_versions_from_MoM(current_mom, 0);
/* load all submanifest minus the one to be removed */
ret = recurse_manifest(current_mom, NULL);
if (ret != 0) {
printf("Error: Cannot load MoM sub-manifests (ret = %d)\n", ret);
ret = ERECURSE_MANIFEST;
goto out_free_mom;
}
consolidate_submanifests(current_mom);
/* Now that we have the consolidated list of all files, load bundle to be removed submanifest*/
ret = load_bundle_manifest(bundle_name, current_version, &bundle_manifest);
if (ret != 0) {
printf("Error: Cannot load %s sub-manifest (ret = %d)\n", bundle_name, ret);
goto out_free_mom;
}
/* deduplication needs file list sorted by filename, do so */
bundle_manifest->files = list_sort(bundle_manifest->files, file_sort_filename);
deduplicate_files_from_manifest(&bundle_manifest, current_mom);
printf("Deleting bundle files...\n");
remove_files_in_manifest_from_fs(bundle_manifest);
printf("Untracking bundle from system...\n");
rm_bundle_file(bundle_name);
printf("Success: Bundle removed\n");
free_manifest(bundle_manifest);
out_free_mom:
free_manifest(current_mom);
out_free_curl:
if (ret) {
printf("Error: Bundle remove failed\n");
}
swupd_curl_cleanup();
v_lockfile(lock_fd);
dump_file_descriptor_leaks();
return ret;
}
/* Attempt to get a write lock protecting the file test/protected_data using
* p_lockfile(). If successful, no two processess should be able to hold the
* lock similtaneously.
*/
static void work(int id)
{
int lock_fd;
int successes = 0;
FILE *file;
char buffer[LINE_MAX];
while (successes < NUM_ACCESS) {
int prev_id = -1;
char prev_action = ' ';
char c = ' ';
// Sleep for a random amount of time, up to half a second so
// not all processes attempt to access lock at once.
usleep(rand() % 500000);
// Attempt to access the lock
lock_fd = p_lockfile();
if (lock_fd < 0) {
printf("process %i unable to acquire lock\n", id);
fflush(stdout);
continue;
}
printf("process %i acquired lock\n", id);
file = fopen(PROTECTED_FILE, "a+");
fseek(file, 0, SEEK_END);
// Check if file is empty
if (ftell(file) != 0) {
// Go to start of last line
while (c != '\n' && fseek(file, -2, SEEK_CUR) == 0) {
c = getc(file);
}
// If the file only has one line, return to start of file
if (c != '\n') {
rewind(file);
}
// Read last line of protected_data
sscanf(fgets(buffer, LINE_MAX, file), "%i%c\n", &prev_id, &prev_action);
}
fprintf(file, "%ip\n", id);
fflush(file);
if (prev_action == 'p') {
printf("process %i accessed lock being held by process %i\n", id, prev_id);
printf("process %i aborting\n\n", id);
return;
}
// Sleep for up to a fifth of a second while holding lock. During this time
// other processes should try to access lock and fail. This sleep is shorter
// than the one before attempting to get the lock because we don't need to
// wait for all other processes to attempt to access lock, just some of them
usleep(rand() % 200000);
fseek(file, 0, SEEK_END);
if (ftell(file) == 0) {
printf("process %i failed to write to protected_data", id);
printf("process %i aborting\n\n", id);
} else {
char c = ' ';
while (c != '\n' && fseek(file, -2, SEEK_CUR) == 0) {
c = getc(file);
}
if (c != '\n') {
rewind(file);
}
sscanf(fgets(buffer, LINE_MAX, file), "%i%c\n", &prev_id, &prev_action);
}
// Log that this thread released the lock
fprintf(file, "%iv\n", id);
fclose(file);
if (prev_action != 'p' || prev_id != id) {
if (prev_id == -1) {
printf("process %i released lock without holding it\n", id);
} else {
printf("process %i and process %i held lock similtaneously\n", id, prev_id);
}
printf("process %i aborting\n\n", id);
return;
}
printf("process %i released lock\n\n", id);
v_lockfile(lock_fd);
successes++;
}
return;
}