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Diffstat (limited to 'login/utmp_file.c')
-rw-r--r--login/utmp_file.c60
1 files changed, 51 insertions, 9 deletions
diff --git a/login/utmp_file.c b/login/utmp_file.c
index 9033f72a4e..fb5840242e 100644
--- a/login/utmp_file.c
+++ b/login/utmp_file.c
@@ -36,6 +36,7 @@
/* Descriptor for the file and position. */
static int file_fd = -1;
+static bool file_writable;
static off64_t file_offset;
/* Cache for the last read entry. */
@@ -138,7 +139,6 @@ setutent_file (void)
if (file_fd < 0)
{
const char *file_name;
- int result;
file_name = TRANSFORM_UTMP_FILE_NAME (__libc_utmp_file_name);
@@ -147,14 +147,10 @@ setutent_file (void)
#else
# define O_flags O_LARGEFILE
#endif
- file_fd = open_not_cancel_2 (file_name, O_RDWR | O_flags);
+ file_writable = false;
+ file_fd = open_not_cancel_2 (file_name, O_RDONLY | O_flags);
if (file_fd == -1)
- {
- /* Hhm, read-write access did not work. Try read-only. */
- file_fd = open_not_cancel_2 (file_name, O_RDONLY | O_flags);
- if (file_fd == -1)
- return 0;
- }
+ return 0;
#ifndef __ASSUME_O_CLOEXEC
# ifdef O_CLOEXEC
@@ -162,7 +158,7 @@ setutent_file (void)
# endif
{
/* We have to make sure the file is `closed on exec'. */
- result = fcntl_not_cancel (file_fd, F_GETFD, 0);
+ int result = fcntl_not_cancel (file_fd, F_GETFD, 0);
if (result >= 0)
{
# ifdef O_CLOEXEC
@@ -404,6 +400,52 @@ pututline_file (const struct utmp *data)
assert (file_fd >= 0);
+ if (! file_writable)
+ {
+ /* We must make the file descriptor writable before going on. */
+ const char *file_name = TRANSFORM_UTMP_FILE_NAME (__libc_utmp_file_name);
+
+ int new_fd = open_not_cancel_2 (file_name, O_RDWR | O_flags);
+ if (new_fd == -1)
+ return NULL;
+
+#ifndef __ASSUME_O_CLOEXEC
+# ifdef O_CLOEXEC
+ if (__have_o_cloexec <= 0)
+# endif
+ {
+ /* We have to make sure the file is `closed on exec'. */
+ int result = fcntl_not_cancel (file_fd, F_GETFD, 0);
+ if (result >= 0)
+ {
+# ifdef O_CLOEXEC
+ if (__have_o_cloexec == 0)
+ __have_o_cloexec = (result & FD_CLOEXEC) ? 1 : -1;
+
+ if (__have_o_cloexec < 0)
+# endif
+ result = fcntl_not_cancel (file_fd, F_SETFD,
+ result | FD_CLOEXEC);
+ }
+
+ if (result == -1)
+ {
+ close_not_cancel_no_status (file_fd);
+ return NULL;
+ }
+ }
+#endif
+
+ if (__lseek64 (new_fd, __lseek64 (file_fd, 0, SEEK_CUR), SEEK_SET) == -1
+ || dup2 (new_fd, file_fd) < 0)
+ {
+ close_not_cancel_no_status (new_fd);
+ return NULL;
+ }
+ close_not_cancel_no_status (new_fd);
+ file_writable = true;
+ }
+
/* Find the correct place to insert the data. */
if (file_offset > 0
&& (