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    Contents of /trunk/mkinitrd-magellan/busybox/miscutils/crontab.c

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    Revision 532 - (show annotations) (download)
    Sat Sep 1 22:45:15 2007 UTC (16 years, 8 months ago) by niro
    File MIME type: text/plain
    File size: 6556 byte(s) 
    -import if magellan mkinitrd; it is a fork of redhats mkinitrd-5.0.8 with all magellan patches and features; deprecates magellan-src/mkinitrd
    1 /* vi: set sw=4 ts=4: */
    2 /*
    3 * CRONTAB
    4 *
    5 * usually setuid root, -c option only works if getuid() == geteuid()
    6 *
    7 * Copyright 1994 Matthew Dillon (dillon@apollo.west.oic.com)
    8 * Vladimir Oleynik <dzo@simtreas.ru> (C) 2002
    9 *
    10 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
    11 */
    12
    13 #include "busybox.h"
    14
    15 #ifndef CRONTABS
    16 #define CRONTABS "/var/spool/cron/crontabs"
    17 #endif
    18 #ifndef TMPDIR
    19 #define TMPDIR "/var/spool/cron"
    20 #endif
    21 #ifndef CRONUPDATE
    22 #define CRONUPDATE "cron.update"
    23 #endif
    24 #ifndef PATH_VI
    25 #define PATH_VI "/bin/vi" /* location of vi */
    26 #endif
    27
    28 static const char *CDir = CRONTABS;
    29
    30 static void EditFile(const char *user, const char *file);
    31 static int GetReplaceStream(const char *user, const char *file);
    32 static int ChangeUser(const char *user, short dochdir);
    33
    34 int crontab_main(int ac, char **av)
    35 {
    36 enum { NONE, EDIT, LIST, REPLACE, DELETE } option = NONE;
    37 const struct passwd *pas;
    38 const char *repFile = NULL;
    39 int repFd = 0;
    40 int i;
    41 char caller[256]; /* user that ran program */
    42 char buf[1024];
    43 int UserId;
    44
    45 UserId = getuid();
    46 pas = getpwuid(UserId);
    47 if (pas == NULL)
    48 bb_perror_msg_and_die("getpwuid");
    49
    50 safe_strncpy(caller, pas->pw_name, sizeof(caller));
    51
    52 i = 1;
    53 if (ac > 1) {
    54 if (LONE_DASH(av[1])) {
    55 option = REPLACE;
    56 ++i;
    57 } else if (av[1][0] != '-') {
    58 option = REPLACE;
    59 ++i;
    60 repFile = av[1];
    61 }
    62 }
    63
    64 for (; i < ac; ++i) {
    65 char *ptr = av[i];
    66
    67 if (*ptr != '-')
    68 break;
    69 ptr += 2;
    70
    71 switch (ptr[-1]) {
    72 case 'l':
    73 if (ptr[-1] == 'l')
    74 option = LIST;
    75 /* fall through */
    76 case 'e':
    77 if (ptr[-1] == 'e')
    78 option = EDIT;
    79 /* fall through */
    80 case 'd':
    81 if (ptr[-1] == 'd')
    82 option = DELETE;
    83 /* fall through */
    84 case 'u':
    85 if (i + 1 < ac && av[i+1][0] != '-') {
    86 ++i;
    87 if (getuid() == geteuid()) {
    88 pas = getpwnam(av[i]);
    89 if (pas) {
    90 UserId = pas->pw_uid;
    91 } else {
    92 bb_error_msg_and_die("user %s unknown", av[i]);
    93 }
    94 } else {
    95 bb_error_msg_and_die("only the superuser may specify a user");
    96 }
    97 }
    98 break;
    99 case 'c':
    100 if (getuid() == geteuid()) {
    101 CDir = (*ptr) ? ptr : av[++i];
    102 } else {
    103 bb_error_msg_and_die("-c option: superuser only");
    104 }
    105 break;
    106 default:
    107 i = ac;
    108 break;
    109 }
    110 }
    111 if (i != ac || option == NONE)
    112 bb_show_usage();
    113
    114 /*
    115 * Get password entry
    116 */
    117
    118 pas = getpwuid(UserId);
    119 if (pas == NULL)
    120 bb_perror_msg_and_die("getpwuid");
    121
    122 /*
    123 * If there is a replacement file, obtain a secure descriptor to it.
    124 */
    125
    126 if (repFile) {
    127 repFd = GetReplaceStream(caller, repFile);
    128 if (repFd < 0)
    129 bb_error_msg_and_die("cannot read replacement file");
    130 }
    131
    132 /*
    133 * Change directory to our crontab directory
    134 */
    135
    136 xchdir(CDir);
    137
    138 /*
    139 * Handle options as appropriate
    140 */
    141
    142 switch (option) {
    143 case LIST:
    144 {
    145 FILE *fi;
    146
    147 fi = fopen(pas->pw_name, "r");
    148 if (fi) {
    149 while (fgets(buf, sizeof(buf), fi) != NULL)
    150 fputs(buf, stdout);
    151 fclose(fi);
    152 } else {
    153 bb_error_msg("no crontab for %s", pas->pw_name);
    154 }
    155 }
    156 break;
    157 case EDIT:
    158 {
    159 /* FIXME: messy code here! we have file copying helpers for this! */
    160 FILE *fi;
    161 int fd;
    162 int n;
    163 char tmp[128];
    164
    165 snprintf(tmp, sizeof(tmp), TMPDIR "/crontab.%d", getpid());
    166 fd = xopen3(tmp, O_RDWR|O_CREAT|O_TRUNC|O_EXCL, 0600);
    167 /* race, use fchown */
    168 chown(tmp, getuid(), getgid());
    169 fi = fopen(pas->pw_name, "r");
    170 if (fi) {
    171 while ((n = fread(buf, 1, sizeof(buf), fi)) > 0)
    172 full_write(fd, buf, n);
    173 }
    174 EditFile(caller, tmp);
    175 remove(tmp);
    176 lseek(fd, 0L, SEEK_SET);
    177 repFd = fd;
    178 }
    179 option = REPLACE;
    180 /* fall through */
    181 case REPLACE:
    182 {
    183 /* same here */
    184 char path[1024];
    185 int fd;
    186 int n;
    187
    188 snprintf(path, sizeof(path), "%s.new", pas->pw_name);
    189 fd = open(path, O_CREAT|O_TRUNC|O_APPEND|O_WRONLY, 0600);
    190 if (fd >= 0) {
    191 while ((n = read(repFd, buf, sizeof(buf))) > 0) {
    192 full_write(fd, buf, n);
    193 }
    194 close(fd);
    195 rename(path, pas->pw_name);
    196 } else {
    197 bb_error_msg("cannot create %s/%s", CDir, path);
    198 }
    199 close(repFd);
    200 }
    201 break;
    202 case DELETE:
    203 remove(pas->pw_name);
    204 break;
    205 case NONE:
    206 default:
    207 break;
    208 }
    209
    210 /*
    211 * Bump notification file. Handle window where crond picks file up
    212 * before we can write our entry out.
    213 */
    214
    215 if (option == REPLACE || option == DELETE) {
    216 FILE *fo;
    217 struct stat st;
    218
    219 while ((fo = fopen(CRONUPDATE, "a"))) {
    220 fprintf(fo, "%s\n", pas->pw_name);
    221 fflush(fo);
    222 if (fstat(fileno(fo), &st) != 0 || st.st_nlink != 0) {
    223 fclose(fo);
    224 break;
    225 }
    226 fclose(fo);
    227 /* loop */
    228 }
    229 if (fo == NULL) {
    230 bb_error_msg("cannot append to %s/%s", CDir, CRONUPDATE);
    231 }
    232 }
    233 return 0;
    234 }
    235
    236 static int GetReplaceStream(const char *user, const char *file)
    237 {
    238 int filedes[2];
    239 int pid;
    240 int fd;
    241 int n;
    242 char buf[1024];
    243
    244 if (pipe(filedes) < 0) {
    245 perror("pipe");
    246 return -1;
    247 }
    248 pid = fork();
    249 if (pid < 0) {
    250 perror("fork");
    251 return -1;
    252 }
    253 if (pid > 0) {
    254 /*
    255 * PARENT
    256 */
    257
    258 close(filedes[1]);
    259 if (read(filedes[0], buf, 1) != 1) {
    260 close(filedes[0]);
    261 filedes[0] = -1;
    262 }
    263 return filedes[0];
    264 }
    265
    266 /*
    267 * CHILD
    268 */
    269
    270 close(filedes[0]);
    271
    272 if (ChangeUser(user, 0) < 0)
    273 exit(0);
    274
    275 xfunc_error_retval = 0;
    276 fd = xopen(file, O_RDONLY);
    277 buf[0] = 0;
    278 write(filedes[1], buf, 1);
    279 while ((n = read(fd, buf, sizeof(buf))) > 0) {
    280 write(filedes[1], buf, n);
    281 }
    282 exit(0);
    283 }
    284
    285 static void EditFile(const char *user, const char *file)
    286 {
    287 int pid = fork();
    288
    289 if (pid == 0) {
    290 /*
    291 * CHILD - change user and run editor
    292 */
    293 char *ptr;
    294 char visual[1024];
    295
    296 if (ChangeUser(user, 1) < 0)
    297 exit(0);
    298 ptr = getenv("VISUAL");
    299 if (ptr == NULL || strlen(ptr) > 256)
    300 ptr = PATH_VI;
    301
    302 snprintf(visual, sizeof(visual), "%s %s", ptr, file);
    303 execl(DEFAULT_SHELL, DEFAULT_SHELL, "-c", visual, NULL);
    304 perror("exec");
    305 exit(0);
    306 }
    307 if (pid < 0) {
    308 /*
    309 * PARENT - failure
    310 */
    311 bb_perror_msg_and_die("fork");
    312 }
    313 wait4(pid, NULL, 0, NULL);
    314 }
    315
    316 static int ChangeUser(const char *user, short dochdir)
    317 {
    318 struct passwd *pas;
    319
    320 /*
    321 * Obtain password entry and change privileges
    322 */
    323
    324 pas = getpwnam(user);
    325 if (pas == NULL) {
    326 bb_perror_msg_and_die("failed to get uid for %s", user);
    327 }
    328 setenv("USER", pas->pw_name, 1);
    329 setenv("HOME", pas->pw_dir, 1);
    330 setenv("SHELL", DEFAULT_SHELL, 1);
    331
    332 /*
    333 * Change running state to the user in question
    334 */
    335 change_identity(pas);
    336
    337 if (dochdir) {
    338 if (chdir(pas->pw_dir) < 0) {
    339 bb_perror_msg("chdir(%s) by %s failed", pas->pw_dir, user);
    340 xchdir(TMPDIR);
    341 }
    342 }
    343 return pas->pw_uid;
    344 }