diff options
| -rw-r--r-- | .gitignore | 2 | ||||
| -rw-r--r-- | CMakeLists.txt | 13 | ||||
| -rw-r--r-- | multihome.c | 501 | ||||
| -rw-r--r-- | multihome.h | 25 |
4 files changed, 541 insertions, 0 deletions
@@ -1,3 +1,5 @@ +.idea/ +cmake-build-debug/ CMakeLists.txt.user CMakeCache.txt CMakeFiles diff --git a/CMakeLists.txt b/CMakeLists.txt new file mode 100644 index 0000000..368e6ce --- /dev/null +++ b/CMakeLists.txt @@ -0,0 +1,13 @@ +cmake_minimum_required(VERSION 3.17) +project(multihome C) + +set(CMAKE_C_STANDARD 99) + +include_directories(.) + +add_executable(multihome + multihome.c + multihome.h) + +install(TARGETS multihome + RUNTIME DESTINATION bin)
\ No newline at end of file diff --git a/multihome.c b/multihome.c new file mode 100644 index 0000000..80234fe --- /dev/null +++ b/multihome.c @@ -0,0 +1,501 @@ +#include <wait.h> +#include <argp.h> +#include <time.h> +#include "multihome.h" + +/** + * Globals + */ +struct { + char path_new[PATH_MAX]; + char path_old[PATH_MAX]; + char path_topdir[PATH_MAX]; + char marker[PATH_MAX]; + char entry_point[PATH_MAX]; + char config_dir[PATH_MAX]; + char config_transfer[PATH_MAX]; + char config_skeleton[PATH_MAX]; + char config_init[PATH_MAX]; +} multihome; + +/** + * Generic function to free an array of pointers + * @param arr an array + * @param nelem if nelem is 0 free until NULL. >0 free until nelem + */ +void free_array(void **arr, size_t nelem) { + if (nelem) { + for (size_t i = 0; i < nelem; i++) { + free(arr[i]); + } + } else { + for (size_t i = 0; arr[i] != NULL; i++) { + free(arr[i]); + } + } + free(arr); + arr = NULL; +} + +/** + * Return the count of a substring in a string + * @param s Input string + * @param sub Input substring + * @return count + */ +ssize_t count_substrings(const char *s, char *sub) { + char *str; + char *str_orig; + size_t str_length; + size_t sub_length; + size_t result; + + str = strdup(s); + if (str == NULL) { + return -1; + } + + str_orig = str; + str_length = strlen(str); + sub_length = strlen(sub); + result = 0; + + for (size_t i = 0; i < str_length; i++) { + char *ptr; + ptr = strstr(str, sub); + + if (ptr) { + result++; + } else { + break; + } + + if (i < str_length - sub_length) { + str = ptr + sub_length; + } + } + + free(str_orig); + return result; +} + +/** + * Split a string using a substring + * @param sptr Input string + * @param delim Substring to split on + * @param num_alloc Address to store count of allocated records + * @return NULL terminated array of strings + */ +char **split(const char *sptr, char *delim, size_t *num_alloc) { + char *s; + char *s_orig; + char **result; + char *token; + + token = NULL; + result = NULL; + s = strdup(sptr); + s_orig = s; + if (s == NULL) { + return NULL; + } + + *num_alloc = count_substrings(s, delim); + if (*num_alloc < 0) { + goto split_die_2; + } + + *num_alloc += 2; + result = calloc(*num_alloc, sizeof(char *)); + + if (result == NULL) { + goto split_die_1; + } + + for (size_t i = 0; (token = strsep(&s, delim)) != NULL; i++) { + result[i] = strdup(token); + if (result[i] == NULL) { + break; + } + } + +split_die_1: + free(s_orig); +split_die_2: + return result; +} + +/** + * Create directories if they do not exist + * @param path Filesystem path + * @return int (0=success, -1=error (errno set)) + */ +int mkdirs(char *path) { + char **parts; + char tmp[PATH_MAX]; + size_t parts_length; + memset(tmp, '\0', sizeof(tmp)); + + parts = split(path, "/", &parts_length); + + for (size_t i = 0; parts[i] != NULL; i++) { + if (i == 0 && strlen(parts[i]) == 0) { + continue; + } + strcat(tmp, "/"); + strcat(tmp, parts[i]); + + if (access(tmp, F_OK) == 0) { + continue; + } + + if (mkdir(tmp, (mode_t) 0755) < 0) { + perror("mkdir"); + return -1; + } + } + + free_array((void **)parts, parts_length); + return 0; +} + +/** + * Execute a shell program + * @param args (char *[]){"/path/to/program", "arg1", "arg2, ..., NULL}; + * @return exit code of program + */ +int shell(char *args[]){ + pid_t pid; + int status; + int child_status; + + status = 0; + child_status = 0; + pid = fork(); + if (pid == 0) { + execvp(args[0], &args[0]); + } else if (pid < 0) { + fprintf(stderr, "failed to execute"); + exit(1); + } else { + if ((waitpid(WAIT_MYPGRP, &child_status, 0)) < 0) { + perror("wait failed"); + exit(1); + } + + if (WIFEXITED(child_status) || WIFSIGNALED(child_status)) { + status = WEXITSTATUS(child_status); + } + } + + return status; +} + +/** + * Copy files using rsync + * @param source file or directory + * @param dest file or directory + * @return rsync exit code + */ +int copy(char *source, char *dest) { + if (source == NULL || dest == NULL) { + fprintf(stderr, "copy failed. source and destination may not be NULL\n"); + exit(1); + } + + return shell((char *[]){RSYNC_BIN, RSYNC_ARGS, source, dest, NULL}); +} + +/** + * Create or update the modified time on a file + * @param filename path to file + * @return 0=success, -1=error (errno set) + */ +int touch(char *filename) { + FILE *fp; + fp = fopen(filename, "w"); + fflush(fp); + if (fp == NULL) { + return -1; + } + fclose(fp); + return 0; +} + +/** + * Generate multihome initialization script + */ +void write_init_script() { + const char *script_block = "#\n# This script was generated on %s\n#\n\n" + "MULTIHOME=%s\n" + "if [ -x $MULTIHOME ]; then\n" + " multihome.old=$HOME\n" + " # Drop environment\n" + " env -i\n" + " # Redeclare HOME\n" + " HOME=$($MULTIHOME)\n" + " if [ \"$HOME\" != \"$multihome.old\" ]; then\n" + " cd $HOME\n" + " fi\n" + "fi\n"; + char buf[PATH_MAX]; + char date[100]; + struct tm *tm; + time_t now; + FILE *fp; + + if (realpath(multihome.entry_point, buf) < 0) { + perror(multihome.entry_point); + exit(errno); + } + + fp = fopen(multihome.config_init, "w+"); + if (fp == NULL) { + perror(multihome.config_init); + exit(errno); + } + + time(&now); + tm = localtime(&now); + sprintf(date, "%02d-%02d-%d @ %02d:%02d:%02d", + tm->tm_mon, tm->tm_mday, tm->tm_year + 1900, + tm->tm_hour, tm->tm_min, tm->tm_sec); + + fprintf(fp, script_block, date, buf); + fclose(fp); +} + +/** + * Link or copy files from /home/username to /home/username/home_local/nodename + */ +void user_transfer() { + FILE *fp; + char config[PATH_MAX]; + char rec[PATH_MAX]; + size_t lineno; + + sprintf(config, "%s/transfer", multihome.config_dir); + memset(rec, '\0', PATH_MAX); + + fp = fopen(config, "r"); + if (fp == NULL) { + // doesn't exist or isn't readable. non-fatal. + return; + } + + // FORMAT: + // TYPE WHERE + // + // TYPE: + // L = SYMBOLIC LINK + // H = HARD LINK + // T = TRANSFER (file, directory, etc) + // + // EXAMPLE: + // L .Xauthority + // L .ssh + // H token.asc + // T special_dotfiles/ + + lineno = 0; + while (fgets(rec, PATH_MAX - 1, fp) != NULL) { + char *recptr; + char source[PATH_MAX]; + char dest[PATH_MAX]; + + recptr = rec; + + // Ignore: comments and inline comments + char *comment; + if (*recptr == '#') { + continue; + } else if ((comment = strstr(recptr, "#")) != NULL) { + comment--; + for (; comment != NULL && isblank(*comment) && comment > recptr; comment--) { + *comment = '\0'; + } + } + + // Ignore: bad lines without enough information + if (strlen(rec) < 3) { + fprintf(stderr, "%s:%zu: Invalid format: %s\n", config, lineno, rec); + continue; + } + + recptr = &rec[2]; + + if (*recptr == '/') { + fprintf(stderr, "%s:%zu: Removing leading '/' from: %s\n", config, lineno, recptr); + memmove(recptr, recptr + 1, strlen(recptr) + 1); + } + + if (recptr[strlen(recptr) - 1] == '\n') { + recptr[strlen(recptr) - 1] = '\0'; + } + + // construct data source path + sprintf(source, "%s/%s", multihome.path_old, recptr); + + // construct data destination path + char *tmp; + tmp = strdup(source); + sprintf(dest, "%s/%s", multihome.path_new, basename(tmp)); + free(tmp); + + switch (rec[0]) { + case 'L': + if (symlink(source, dest) < 0) { + fprintf(stderr, "symlink: %s: %s -> %s\n", strerror(errno), source, dest); + } + break; + case 'H': + if (link(source, dest) < 0) { + fprintf(stderr, "hardlink: %s: %s -> %s\n", strerror(errno), source, dest); + } + break; + case 'T': + if (copy(source, dest) != 0) { + fprintf(stderr, "transfer: %s: %s -> %s\n", strerror(errno), source, dest); + } + break; + default: + fprintf(stderr, "%s:%zu: Invalid type: %c\n", config, lineno, rec[0]); + break; + } + } +} + +// begin argp setup +static char doc[] = "Partition a home directory per-host when using a centrally mounted /home"; +static char args_doc[] = ""; +static struct argp_option options[] = { + {"script", 's', 0, 0, "Generate runtime script"}, + {"version", 'V', 0, 0, "Show version and exit"}, + {0}, +}; + +struct arguments { + int script; + int version; +}; + +static error_t parse_opt (int key, char *arg, struct argp_state *state) { + struct arguments *arguments = state->input; + (void) arg; // arg is not used + + switch (key) { + case 'V': + arguments->version = 1; + break; + case 's': + arguments->script = 1; + break; + case ARGP_KEY_ARG: + if (state->arg_num > 1) { + argp_usage(state); + } + break; + default: + return ARGP_ERR_UNKNOWN; + } + return 0; +} + +static struct argp argp = { options, parse_opt, args_doc, doc }; +// end of argp setup + +int main(int argc, char *argv[]) { + uid_t uid; + struct passwd *user_info; + struct utsname host_info; + + struct arguments arguments; + arguments.script = 0; + arguments.version = 0; + argp_parse(&argp, argc, argv, 0, 0, &arguments); + + if (arguments.version) { + puts(VERSION); + exit(0); + } + + // Get account name for the effective user + uid = geteuid(); + if ((user_info = getpwuid(uid)) == NULL) { + perror("getpwuid"); + return errno; + } + + // Get host information + if (uname(&host_info) < 0) { + perror("uname"); + return errno; + } + + // Populate multihome struct + strcpy(multihome.entry_point, argv[0]); + strcpy(multihome.path_old, getenv("HOME")); + sprintf(multihome.config_dir, "%s/.multihome", multihome.path_old); + sprintf(multihome.config_init, "%s/init", multihome.config_dir); + sprintf(multihome.config_skeleton, "%s/skel/", multihome.config_dir); + sprintf(multihome.path_new, "/home/%s/home_local/%s", user_info->pw_name, host_info.nodename); + sprintf(multihome.path_topdir, "%s/topdir", multihome.path_new); + sprintf(multihome.marker, "%s/.multihome_controlled", multihome.path_new); + + + // Create new home directory + if (strcmp(multihome.path_new, multihome.path_old) != 0) { + if (access(multihome.path_new, F_OK) < 0) { + fprintf(stderr, "Creating home directory: %s\n", multihome.path_new); + if (mkdirs(multihome.path_new) < 0) { + perror(multihome.path_new); + return errno; + } + } + } + + // Generate symbolic link within the new home directory pointing back to the real account home directory + if (access(multihome.path_topdir, F_OK) != 0 ) { + fprintf(stderr, "Creating symlink to original home directory: %s\n", multihome.path_topdir); + if (symlink(multihome.path_new, multihome.path_topdir) < 0) { + perror(multihome.path_topdir); + return errno; + } + } + + // Generate directory for user-defined account defaults + // Files placed here will be copied to the new home directory. + if (access(multihome.config_skeleton, F_OK) < 0) { + fprintf(stderr, "Creating user skel directory: %s\n", multihome.config_skeleton); + if (mkdirs(multihome.config_skeleton) < 0) { + perror(multihome.config_skeleton); + return errno; + } + } + + if (access(multihome.marker, F_OK) < 0) { + // Copy system account defaults + fprintf(stderr, "Injecting account skeleton: %s\n", OS_SKEL_DIR); + copy(OS_SKEL_DIR, multihome.path_new); + + // Copy user-defined account defaults + fprintf(stderr, "Injecting user-defined account skeleton: %s\n", multihome.config_skeleton); + copy(multihome.config_skeleton, multihome.path_new); + + // Transfer or link user-defined files into the new home + fprintf(stderr, "Parsing transfer configuration, if present\n"); + user_transfer(); + } + + // Leave our mark: "multihome was here" + if (access(multihome.marker, F_OK) < 0) { + fprintf(stderr, "Creating marker file: %s\n", multihome.marker); + touch(multihome.marker); + } + + if (arguments.script) { + write_init_script(); + } else { + printf("%s\n", multihome.path_new); + } +}
\ No newline at end of file diff --git a/multihome.h b/multihome.h new file mode 100644 index 0000000..a9b401f --- /dev/null +++ b/multihome.h @@ -0,0 +1,25 @@ +// +// Created by jhunk on 8/26/20. +// + +#ifndef MULTIHOME_MULTIHOME_H +#define MULTIHOME_MULTIHOME_H + +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <limits.h> +#include <pwd.h> +#include <sys/utsname.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <libgen.h> + +#define VERSION "0.0.1" +#define OS_SKEL_DIR "/etc/skel/" // NOTE: Trailing slash is required +#define RSYNC_BIN "/usr/bin/rsync" +#define RSYNC_ARGS "-aq" + +#endif //MULTIHOME_MULTIHOME_H |