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-rw-r--r--login/utmp_file.c499
1 files changed, 499 insertions, 0 deletions
diff --git a/login/utmp_file.c b/login/utmp_file.c
new file mode 100644
index 0000000000..e7743bfac8
--- /dev/null
+++ b/login/utmp_file.c
@@ -0,0 +1,499 @@
+/* Copyright (C) 1996-2002, 2003, 2004 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@cygnus.com>
+ and Paul Janzen <pcj@primenet.com>, 1996.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <utmp.h>
+#include <not-cancel.h>
+
+#include "utmp-private.h"
+#include "utmp-equal.h"
+
+
+/* Descriptor for the file and position. */
+static int file_fd = -1;
+static off64_t file_offset;
+
+/* Cache for the last read entry. */
+static struct utmp last_entry;
+
+
+/* Locking timeout. */
+#ifndef TIMEOUT
+# define TIMEOUT 1
+#endif
+
+/* Do-nothing handler for locking timeout. */
+static void timeout_handler (int signum) {};
+
+/* LOCK_FILE(fd, type) failure_statement
+ attempts to get a lock on the utmp file referenced by FD. If it fails,
+ the failure_statement is executed, otherwise it is skipped.
+ LOCKING_FAILED()
+ jumps into the UNLOCK_FILE macro and ensures cleanup of LOCK_FILE.
+ UNLOCK_FILE(fd)
+ unlocks the utmp file referenced by FD and performs the cleanup of
+ LOCK_FILE.
+ */
+#define LOCK_FILE(fd, type) \
+{ \
+ struct flock fl; \
+ struct sigaction action, old_action; \
+ unsigned int old_timeout; \
+ \
+ /* Cancel any existing alarm. */ \
+ old_timeout = alarm (0); \
+ \
+ /* Establish signal handler. */ \
+ action.sa_handler = timeout_handler; \
+ __sigemptyset (&action.sa_mask); \
+ action.sa_flags = 0; \
+ __sigaction (SIGALRM, &action, &old_action); \
+ \
+ alarm (TIMEOUT); \
+ \
+ /* Try to get the lock. */ \
+ memset (&fl, '\0', sizeof (struct flock)); \
+ fl.l_type = (type); \
+ fl.l_whence = SEEK_SET; \
+ if (fcntl_not_cancel ((fd), F_SETLKW, &fl) < 0)
+
+#define LOCKING_FAILED() \
+ goto unalarm_return
+
+#define UNLOCK_FILE(fd) \
+ /* Unlock the file. */ \
+ fl.l_type = F_UNLCK; \
+ fcntl_not_cancel ((fd), F_SETLKW, &fl); \
+ \
+ unalarm_return: \
+ /* Reset the signal handler and alarm. We must reset the alarm \
+ before resetting the handler so our alarm does not generate a \
+ spurious SIGALRM seen by the user. However, we cannot just set \
+ the user's old alarm before restoring the handler, because then \
+ it's possible our handler could catch the user alarm's SIGARLM \
+ and then the user would never see the signal he expected. */ \
+ alarm (0); \
+ __sigaction (SIGALRM, &old_action, NULL); \
+ if (old_timeout != 0) \
+ alarm (old_timeout); \
+} while (0)
+
+
+/* Functions defined here. */
+static int setutent_file (void);
+static int getutent_r_file (struct utmp *buffer, struct utmp **result);
+static int getutid_r_file (const struct utmp *key, struct utmp *buffer,
+ struct utmp **result);
+static int getutline_r_file (const struct utmp *key, struct utmp *buffer,
+ struct utmp **result);
+static struct utmp *pututline_file (const struct utmp *data);
+static void endutent_file (void);
+static int updwtmp_file (const char *file, const struct utmp *utmp);
+
+/* Jump table for file functions. */
+const struct utfuncs __libc_utmp_file_functions =
+{
+ setutent_file,
+ getutent_r_file,
+ getutid_r_file,
+ getutline_r_file,
+ pututline_file,
+ endutent_file,
+ updwtmp_file
+};
+
+
+#ifndef TRANSFORM_UTMP_FILE_NAME
+# define TRANSFORM_UTMP_FILE_NAME(file_name) (file_name)
+#endif
+
+static int
+setutent_file (void)
+{
+ if (file_fd < 0)
+ {
+ const char *file_name;
+ int result;
+
+ file_name = TRANSFORM_UTMP_FILE_NAME (__libc_utmp_file_name);
+
+ file_fd = open_not_cancel_2 (file_name, O_RDWR);
+ if (file_fd == -1)
+ {
+ /* Hhm, read-write access did not work. Try read-only. */
+ file_fd = open_not_cancel_2 (file_name, O_RDONLY);
+ if (file_fd == -1)
+ return 0;
+ }
+
+ /* We have to make sure the file is `closed on exec'. */
+ result = fcntl_not_cancel (file_fd, F_GETFD, 0);
+ if (result >= 0)
+ result = fcntl_not_cancel (file_fd, F_SETFD, result | FD_CLOEXEC);
+ if (result == -1)
+ {
+ close_not_cancel_no_status (file_fd);
+ return 0;
+ }
+ }
+
+ __lseek64 (file_fd, 0, SEEK_SET);
+ file_offset = 0;
+
+ /* Make sure the entry won't match. */
+#if _HAVE_UT_TYPE - 0
+ last_entry.ut_type = -1;
+#else
+ last_entry.ut_line[0] = '\177';
+# if _HAVE_UT_ID - 0
+ last_entry.ut_id[0] = '\0';
+# endif
+#endif
+
+ return 1;
+}
+
+
+static int
+getutent_r_file (struct utmp *buffer, struct utmp **result)
+{
+ ssize_t nbytes;
+
+ assert (file_fd >= 0);
+
+ if (file_offset == -1l)
+ {
+ /* Not available. */
+ *result = NULL;
+ return -1;
+ }
+
+ LOCK_FILE (file_fd, F_RDLCK)
+ {
+ nbytes = 0;
+ LOCKING_FAILED ();
+ }
+
+ /* Read the next entry. */
+ nbytes = read_not_cancel (file_fd, &last_entry, sizeof (struct utmp));
+
+ UNLOCK_FILE (file_fd);
+
+ if (nbytes != sizeof (struct utmp))
+ {
+ if (nbytes != 0)
+ file_offset = -1l;
+ *result = NULL;
+ return -1;
+ }
+
+ /* Update position pointer. */
+ file_offset += sizeof (struct utmp);
+
+ memcpy (buffer, &last_entry, sizeof (struct utmp));
+ *result = buffer;
+
+ return 0;
+}
+
+
+static int
+internal_getut_r (const struct utmp *id, struct utmp *buffer)
+{
+ int result = -1;
+
+ LOCK_FILE (file_fd, F_RDLCK)
+ LOCKING_FAILED ();
+
+#if _HAVE_UT_TYPE - 0
+ if (id->ut_type == RUN_LVL || id->ut_type == BOOT_TIME
+ || id->ut_type == OLD_TIME || id->ut_type == NEW_TIME)
+ {
+ /* Search for next entry with type RUN_LVL, BOOT_TIME,
+ OLD_TIME, or NEW_TIME. */
+
+ while (1)
+ {
+ /* Read the next entry. */
+ if (read_not_cancel (file_fd, buffer, sizeof (struct utmp))
+ != sizeof (struct utmp))
+ {
+ __set_errno (ESRCH);
+ file_offset = -1l;
+ goto unlock_return;
+ }
+ file_offset += sizeof (struct utmp);
+
+ if (id->ut_type == buffer->ut_type)
+ break;
+ }
+ }
+ else
+#endif /* _HAVE_UT_TYPE */
+ {
+ /* Search for the next entry with the specified ID and with type
+ INIT_PROCESS, LOGIN_PROCESS, USER_PROCESS, or DEAD_PROCESS. */
+
+ while (1)
+ {
+ /* Read the next entry. */
+ if (read_not_cancel (file_fd, buffer, sizeof (struct utmp))
+ != sizeof (struct utmp))
+ {
+ __set_errno (ESRCH);
+ file_offset = -1l;
+ goto unlock_return;
+ }
+ file_offset += sizeof (struct utmp);
+
+ if (__utmp_equal (buffer, id))
+ break;
+ }
+ }
+
+ result = 0;
+
+unlock_return:
+ UNLOCK_FILE (file_fd);
+
+ return result;
+}
+
+
+/* For implementing this function we don't use the getutent_r function
+ because we can avoid the reposition on every new entry this way. */
+static int
+getutid_r_file (const struct utmp *id, struct utmp *buffer,
+ struct utmp **result)
+{
+ assert (file_fd >= 0);
+
+ if (file_offset == -1l)
+ {
+ *result = NULL;
+ return -1;
+ }
+
+ if (internal_getut_r (id, &last_entry) < 0)
+ {
+ *result = NULL;
+ return -1;
+ }
+
+ memcpy (buffer, &last_entry, sizeof (struct utmp));
+ *result = buffer;
+
+ return 0;
+}
+
+
+/* For implementing this function we don't use the getutent_r function
+ because we can avoid the reposition on every new entry this way. */
+static int
+getutline_r_file (const struct utmp *line, struct utmp *buffer,
+ struct utmp **result)
+{
+ assert (file_fd >= 0);
+
+ if (file_offset == -1l)
+ {
+ *result = NULL;
+ return -1;
+ }
+
+ LOCK_FILE (file_fd, F_RDLCK)
+ {
+ *result = NULL;
+ LOCKING_FAILED ();
+ }
+
+ while (1)
+ {
+ /* Read the next entry. */
+ if (read_not_cancel (file_fd, &last_entry, sizeof (struct utmp))
+ != sizeof (struct utmp))
+ {
+ __set_errno (ESRCH);
+ file_offset = -1l;
+ *result = NULL;
+ goto unlock_return;
+ }
+ file_offset += sizeof (struct utmp);
+
+ /* Stop if we found a user or login entry. */
+ if (
+#if _HAVE_UT_TYPE - 0
+ (last_entry.ut_type == USER_PROCESS
+ || last_entry.ut_type == LOGIN_PROCESS)
+ &&
+#endif
+ !strncmp (line->ut_line, last_entry.ut_line, sizeof line->ut_line))
+ break;
+ }
+
+ memcpy (buffer, &last_entry, sizeof (struct utmp));
+ *result = buffer;
+
+unlock_return:
+ UNLOCK_FILE (file_fd);
+
+ return ((*result == NULL) ? -1 : 0);
+}
+
+
+static struct utmp *
+pututline_file (const struct utmp *data)
+{
+ struct utmp buffer;
+ struct utmp *pbuf;
+ int found;
+
+ assert (file_fd >= 0);
+
+ /* Find the correct place to insert the data. */
+ if (file_offset > 0
+ && (
+#if _HAVE_UT_TYPE - 0
+ (last_entry.ut_type == data->ut_type
+ && (last_entry.ut_type == RUN_LVL
+ || last_entry.ut_type == BOOT_TIME
+ || last_entry.ut_type == OLD_TIME
+ || last_entry.ut_type == NEW_TIME))
+ ||
+#endif
+ __utmp_equal (&last_entry, data)))
+ found = 1;
+ else
+ found = internal_getut_r (data, &buffer);
+
+ LOCK_FILE (file_fd, F_WRLCK)
+ {
+ pbuf = NULL;
+ LOCKING_FAILED ();
+ }
+
+ if (found < 0)
+ {
+ /* We append the next entry. */
+ file_offset = __lseek64 (file_fd, 0, SEEK_END);
+ if (file_offset % sizeof (struct utmp) != 0)
+ {
+ file_offset -= file_offset % sizeof (struct utmp);
+ __ftruncate64 (file_fd, file_offset);
+
+ if (__lseek64 (file_fd, 0, SEEK_END) < 0)
+ {
+ pbuf = NULL;
+ goto unlock_return;
+ }
+ }
+ }
+ else
+ {
+ /* We replace the just read entry. */
+ file_offset -= sizeof (struct utmp);
+ __lseek64 (file_fd, file_offset, SEEK_SET);
+ }
+
+ /* Write the new data. */
+ if (write_not_cancel (file_fd, data, sizeof (struct utmp))
+ != sizeof (struct utmp))
+ {
+ /* If we appended a new record this is only partially written.
+ Remove it. */
+ if (found < 0)
+ (void) __ftruncate64 (file_fd, file_offset);
+ pbuf = NULL;
+ }
+ else
+ {
+ file_offset += sizeof (struct utmp);
+ pbuf = (struct utmp *) data;
+ }
+
+ unlock_return:
+ UNLOCK_FILE (file_fd);
+
+ return pbuf;
+}
+
+
+static void
+endutent_file (void)
+{
+ assert (file_fd >= 0);
+
+ close_not_cancel_no_status (file_fd);
+ file_fd = -1;
+}
+
+
+static int
+updwtmp_file (const char *file, const struct utmp *utmp)
+{
+ int result = -1;
+ off64_t offset;
+ int fd;
+
+ /* Open WTMP file. */
+ fd = open_not_cancel_2 (file, O_WRONLY);
+ if (fd < 0)
+ return -1;
+
+ LOCK_FILE (fd, F_WRLCK)
+ LOCKING_FAILED ();
+
+ /* Remember original size of log file. */
+ offset = __lseek64 (fd, 0, SEEK_END);
+ if (offset % sizeof (struct utmp) != 0)
+ {
+ offset -= offset % sizeof (struct utmp);
+ __ftruncate64 (fd, offset);
+
+ if (__lseek64 (fd, 0, SEEK_END) < 0)
+ goto unlock_return;
+ }
+
+ /* Write the entry. If we can't write all the bytes, reset the file
+ size back to the original size. That way, no partial entries
+ will remain. */
+ if (write_not_cancel (fd, utmp, sizeof (struct utmp))
+ != sizeof (struct utmp))
+ {
+ __ftruncate64 (fd, offset);
+ goto unlock_return;
+ }
+
+ result = 0;
+
+unlock_return:
+ UNLOCK_FILE (fd);
+
+ /* Close WTMP file. */
+ close_not_cancel_no_status (fd);
+
+ return result;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-04-27 08:39:23 +0000