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[glibc] login: Remove utmp backend jump tables [BZ #23518]
- From: Florian Weimer <fw at sourceware dot org>
- To: glibc-cvs at sourceware dot org
- Date: 5 Aug 2019 13:55:38 -0000
- Subject: [glibc] login: Remove utmp backend jump tables [BZ #23518]
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=1a7fe2ebe52b3c8bf465d1756e69452d05c1c103
commit 1a7fe2ebe52b3c8bf465d1756e69452d05c1c103
Author: Florian Weimer <fweimer@redhat.com>
Date: Mon Aug 5 15:54:10 2019 +0200
login: Remove utmp backend jump tables [BZ #23518]
There is just one file-based implementation, so this dispatch
mechanism is unnecessary. Instead of the vtable pointer
__libc_utmp_jump_table, use a non-negative file_fd as the indicator
that the backend is initialized.
Diff:
---
ChangeLog | 40 +++++++++++++++++
login/getutent_r.c | 108 ++--------------------------------------------
login/getutid_r.c | 2 +-
login/getutline_r.c | 2 +-
login/updwtmp.c | 2 +-
login/utmp-private.h | 29 +++++--------
login/utmp_file.c | 89 ++++++++++++++------------------------
login/utmpname.c | 3 +-
manual/users.texi | 20 ++++-----
sysdeps/unix/getlogin_r.c | 7 ++-
10 files changed, 105 insertions(+), 197 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index a67110e..bf72799 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,43 @@
+2019-08-05 Florian Weimer <fweimer@redhat.com>
+
+ [BZ #23518]
+ * login/uptmp-private.h (struct ufuncs): Remove definition.
+ (__libc_utmp_file_functions, __libc_utmp_unknown_functions)
+ (__libc_utmp_jump_table): Remove declarations.
+ (__libc_setutent, __libc_getutent_r, __libc_getutid_r)
+ (__libc_getutline_r, __libc_pututline, __libc_endutent)
+ (__libc_updwtmp): Declare.
+ * login/getutent_r.c (__libc_utmp_unknown_functions)
+ (__libc_utmp_jump_table, setutent_unknown, getutent_r_unknown)
+ (getutid_r_unknown, getutline_r_unknown, pututline_unknown)
+ (endutent_unknown): Remove definitions.
+ (__setutent): Call __libc_setutent.
+ (__getutent_r): Call __libc_getutent_r.
+ (__pututline): Call __libc_pututline.
+ (__endutent): Call __libc_endutent.
+ * login/getutid_r.c (__getutid_r): Call __libc_getutid_r.
+ * login/getutline_r.c (__getutline_r): Call __libc_getutline_r.
+ * login/updwtmp.c (__updwtmp): Call __libc_updwtmp.
+ * login/utmp_file.c (__libc_utmp_file_functions): Remove definition
+ (__libc_setutent): Rename from stetutent_file. Drop static.
+ (maybe_setutent): New function.
+ (__libc_getutent_r): Rename from getutent_r_file. Drop static.
+ Check for initialization.
+ (__libc_getutid_r): Rename from getutid_r_file. Drop static.
+ Check for initialization.
+ (__libc_getutline_r): Rename from getutline_r_file. Drop static.
+ Check for initialization.
+ (__libc_pututline): Rename from pututline_file. Drop static.
+ Check for initialization.
+ (__libc_endutent): Rename from endutent_file. Drop static. Check
+ for initialization.
+ (__libc_updwtmp): Rename from updwtmp_file. Drop static.
+ * login/utmpname.c (__utmpname): Call __libc_endutent.
+ * sysdeps/unix/getlogin_r (__getlogin_r): Call __libc_setutent,
+ __libc_getutlien_r, __libc_endutent.
+ * manual/users.texi (Who Logged In, Manipulating the Database):
+ Adjust.
+
2019-08-05 Alexandra Hajkova <ahajkova@redhat.com>
* elf/tst-ldconfig-bad-aux-cache.c: Use support_capture_subprocess.
diff --git a/login/getutent_r.c b/login/getutent_r.c
index 98ffc5d..fd13be8 100644
--- a/login/getutent_r.c
+++ b/login/getutent_r.c
@@ -23,115 +23,16 @@
#include "utmp-private.h"
-
-/* Functions defined here. */
-static int setutent_unknown (void);
-static int getutent_r_unknown (struct utmp *buffer, struct utmp **result);
-static int getutid_r_unknown (const struct utmp *line, struct utmp *buffer,
- struct utmp **result);
-static int getutline_r_unknown (const struct utmp *id, struct utmp *buffer,
- struct utmp **result);
-static struct utmp *pututline_unknown (const struct utmp *data);
-static void endutent_unknown (void);
-
-/* Initial Jump table. */
-const struct utfuncs __libc_utmp_unknown_functions =
-{
- setutent_unknown,
- getutent_r_unknown,
- getutid_r_unknown,
- getutline_r_unknown,
- pututline_unknown,
- endutent_unknown,
- NULL
-};
-
-/* Currently selected backend. */
-const struct utfuncs *__libc_utmp_jump_table = &__libc_utmp_unknown_functions;
-
/* We need to protect the opening of the file. */
__libc_lock_define_initialized (, __libc_utmp_lock attribute_hidden)
-static int
-setutent_unknown (void)
-{
- int result;
-
- result = (*__libc_utmp_file_functions.setutent) ();
- if (result)
- __libc_utmp_jump_table = &__libc_utmp_file_functions;
-
- return result;
-}
-
-
-static int
-getutent_r_unknown (struct utmp *buffer, struct utmp **result)
-{
- /* The backend was not yet initialized. */
- if (setutent_unknown ())
- return (*__libc_utmp_jump_table->getutent_r) (buffer, result);
-
- /* Not available. */
- *result = NULL;
- return -1;
-}
-
-
-static int
-getutid_r_unknown (const struct utmp *id, struct utmp *buffer,
- struct utmp **result)
-{
- /* The backend was not yet initialized. */
- if (setutent_unknown ())
- return (*__libc_utmp_jump_table->getutid_r) (id, buffer, result);
-
- /* Not available. */
- *result = NULL;
- return -1;
-}
-
-
-static int
-getutline_r_unknown (const struct utmp *line, struct utmp *buffer,
- struct utmp **result)
-{
- /* The backend was not yet initialized. */
- if (setutent_unknown ())
- return (*__libc_utmp_jump_table->getutline_r) (line, buffer, result);
-
- /* Not available. */
- *result = NULL;
- return -1;
-}
-
-
-static struct utmp *
-pututline_unknown (const struct utmp *data)
-{
- /* The backend was not yet initialized. */
- if (setutent_unknown ())
- return (*__libc_utmp_jump_table->pututline) (data);
-
- /* Not available. */
- return NULL;
-}
-
-
-static void
-endutent_unknown (void)
-{
- /* Nothing to do. */
-}
-
-
void
__setutent (void)
{
__libc_lock_lock (__libc_utmp_lock);
- (*__libc_utmp_jump_table->setutent) ();
+ __libc_setutent ();
__libc_lock_unlock (__libc_utmp_lock);
}
@@ -145,7 +46,7 @@ __getutent_r (struct utmp *buffer, struct utmp **result)
__libc_lock_lock (__libc_utmp_lock);
- retval = (*__libc_utmp_jump_table->getutent_r) (buffer, result);
+ retval = __libc_getutent_r (buffer, result);
__libc_lock_unlock (__libc_utmp_lock);
@@ -162,7 +63,7 @@ __pututline (const struct utmp *data)
__libc_lock_lock (__libc_utmp_lock);
- buffer = (*__libc_utmp_jump_table->pututline) (data);
+ buffer = __libc_pututline (data);
__libc_lock_unlock (__libc_utmp_lock);
@@ -177,8 +78,7 @@ __endutent (void)
{
__libc_lock_lock (__libc_utmp_lock);
- (*__libc_utmp_jump_table->endutent) ();
- __libc_utmp_jump_table = &__libc_utmp_unknown_functions;
+ __libc_endutent ();
__libc_lock_unlock (__libc_utmp_lock);
}
diff --git a/login/getutid_r.c b/login/getutid_r.c
index 34ea61d..86ffc85 100644
--- a/login/getutid_r.c
+++ b/login/getutid_r.c
@@ -49,7 +49,7 @@ __getutid_r (const struct utmp *id, struct utmp *buffer, struct utmp **result)
__libc_lock_lock (__libc_utmp_lock);
- retval = (*__libc_utmp_jump_table->getutid_r) (id, buffer, result);
+ retval = __libc_getutid_r (id, buffer, result);
__libc_lock_unlock (__libc_utmp_lock);
diff --git a/login/getutline_r.c b/login/getutline_r.c
index 110b89e..f03255d 100644
--- a/login/getutline_r.c
+++ b/login/getutline_r.c
@@ -36,7 +36,7 @@ __getutline_r (const struct utmp *line, struct utmp *buffer,
__libc_lock_lock (__libc_utmp_lock);
- retval = (*__libc_utmp_jump_table->getutline_r) (line, buffer, result);
+ retval = __libc_getutline_r (line, buffer, result);
__libc_lock_unlock (__libc_utmp_lock);
diff --git a/login/updwtmp.c b/login/updwtmp.c
index b9bccd9..387e580 100644
--- a/login/updwtmp.c
+++ b/login/updwtmp.c
@@ -29,7 +29,7 @@ __updwtmp (const char *wtmp_file, const struct utmp *utmp)
{
const char *file_name = TRANSFORM_UTMP_FILE_NAME (wtmp_file);
- (*__libc_utmp_file_functions.updwtmp) (file_name, utmp);
+ __libc_updwtmp (file_name, utmp);
}
libc_hidden_def (__updwtmp)
weak_alias (__updwtmp, updwtmp)
diff --git a/login/utmp-private.h b/login/utmp-private.h
index a82a923..d60461d 100644
--- a/login/utmp-private.h
+++ b/login/utmp-private.h
@@ -24,24 +24,17 @@
#include <utmp.h>
#include <libc-lock.h>
-/* The structure describing the functions in a backend. */
-struct utfuncs
-{
- int (*setutent) (void);
- int (*getutent_r) (struct utmp *, struct utmp **);
- int (*getutid_r) (const struct utmp *, struct utmp *, struct utmp **);
- int (*getutline_r) (const struct utmp *, struct utmp *, struct utmp **);
- struct utmp *(*pututline) (const struct utmp *);
- void (*endutent) (void);
- int (*updwtmp) (const char *, const struct utmp *);
-};
-
-/* The tables from the services. */
-extern const struct utfuncs __libc_utmp_file_functions attribute_hidden;
-extern const struct utfuncs __libc_utmp_unknown_functions attribute_hidden;
-
-/* Currently selected backend. */
-extern const struct utfuncs *__libc_utmp_jump_table attribute_hidden;
+/* These functions check for initialization, but not perform any
+ locking. */
+int __libc_setutent (void) attribute_hidden;
+int __libc_getutent_r (struct utmp *, struct utmp **) attribute_hidden;
+int __libc_getutid_r (const struct utmp *, struct utmp *, struct utmp **)
+ attribute_hidden;
+int __libc_getutline_r (const struct utmp *, struct utmp *, struct utmp **)
+ attribute_hidden;
+struct utmp *__libc_pututline (const struct utmp *) attribute_hidden;
+void __libc_endutent (void) attribute_hidden;
+int __libc_updwtmp (const char *, const struct utmp *) attribute_hidden;
/* Current file name. */
extern const char *__libc_utmp_file_name attribute_hidden;
diff --git a/login/utmp_file.c b/login/utmp_file.c
index b19d3ca..cb8a028 100644
--- a/login/utmp_file.c
+++ b/login/utmp_file.c
@@ -105,37 +105,12 @@ static void timeout_handler (int signum) {};
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)
+int
+__libc_setutent (void)
{
if (file_fd < 0)
{
@@ -166,15 +141,19 @@ setutent_file (void)
return 1;
}
+/* Preform initialization if necessary. */
+static bool
+maybe_setutent (void)
+{
+ return file_fd >= 0 || __libc_setutent ();
+}
-static int
-getutent_r_file (struct utmp *buffer, struct utmp **result)
+int
+__libc_getutent_r (struct utmp *buffer, struct utmp **result)
{
ssize_t nbytes;
- assert (file_fd >= 0);
-
- if (file_offset == -1l)
+ if (!maybe_setutent () || file_offset == -1l)
{
/* Not available. */
*result = NULL;
@@ -279,13 +258,11 @@ unlock_return:
/* 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)
+int
+__libc_getutid_r (const struct utmp *id, struct utmp *buffer,
+ struct utmp **result)
{
- assert (file_fd >= 0);
-
- if (file_offset == -1l)
+ if (!maybe_setutent () || file_offset == -1l)
{
*result = NULL;
return -1;
@@ -309,13 +286,11 @@ getutid_r_file (const struct utmp *id, struct utmp *buffer,
/* 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)
+int
+__libc_getutline_r (const struct utmp *line, struct utmp *buffer,
+ struct utmp **result)
{
- assert (file_fd >= 0);
-
- if (file_offset == -1l)
+ if (!maybe_setutent () || file_offset == -1l)
{
*result = NULL;
return -1;
@@ -361,15 +336,16 @@ unlock_return:
}
-static struct utmp *
-pututline_file (const struct utmp *data)
+struct utmp *
+__libc_pututline (const struct utmp *data)
{
+ if (!maybe_setutent ())
+ return NULL;
+
struct utmp buffer;
struct utmp *pbuf;
int found;
- assert (file_fd >= 0);
-
if (! file_writable)
{
/* We must make the file descriptor writable before going on. */
@@ -467,18 +443,19 @@ pututline_file (const struct utmp *data)
}
-static void
-endutent_file (void)
+void
+__libc_endutent (void)
{
- assert (file_fd >= 0);
-
- __close_nocancel_nostatus (file_fd);
- file_fd = -1;
+ if (file_fd >= 0)
+ {
+ __close_nocancel_nostatus (file_fd);
+ file_fd = -1;
+ }
}
-static int
-updwtmp_file (const char *file, const struct utmp *utmp)
+int
+__libc_updwtmp (const char *file, const struct utmp *utmp)
{
int result = -1;
off64_t offset;
diff --git a/login/utmpname.c b/login/utmpname.c
index c3da183..8f94b19 100644
--- a/login/utmpname.c
+++ b/login/utmpname.c
@@ -42,8 +42,7 @@ __utmpname (const char *file)
__libc_lock_lock (__libc_utmp_lock);
/* Close the old file. */
- (*__libc_utmp_jump_table->endutent) ();
- __libc_utmp_jump_table = &__libc_utmp_unknown_functions;
+ __libc_endutent ();
if (strcmp (file, __libc_utmp_file_name) != 0)
{
diff --git a/manual/users.texi b/manual/users.texi
index 96ed206..ec22ce6 100644
--- a/manual/users.texi
+++ b/manual/users.texi
@@ -894,9 +894,9 @@ The @code{getlogin} function is declared in @file{unistd.h}, while
@c ttyname_r dup @ascuheap @acsmem @acsfd
@c strncpy dup ok
@c libc_lock_lock dup @asulock @aculock
-@c *libc_utmp_jump_table->setutent dup @mtasurace:utent @acsfd
-@c *libc_utmp_jump_table->getutline_r dup @mtasurace:utent @mtascusig:ALRM @mtascutimer
-@c *libc_utmp_jump_table->endutent dup @mtasurace:utent @asulock @aculock
+@c __libc_setutent dup @mtasurace:utent @acsfd
+@c __libc_getutline_r dup @mtasurace:utent @mtascusig:ALRM @mtascutimer
+@c __libc_endutent dup @mtasurace:utent @asulock @aculock
@c libc_lock_unlock dup ok
@c strlen dup ok
@c memcpy dup ok
@@ -1111,7 +1111,7 @@ compatibility only, @file{utmp.h} defines @code{ut_time} as an alias for
@c setutent @mtasurace:utent @asulock @aculock @acsfd
@c libc_lock_lock dup @asulock @aculock
-@c *libc_utmp_jump_table->setutent @mtasurace:utent @acsfd
+@c __libc_setutent @mtasurace:utent @acsfd
@c setutent_unknown @mtasurace:utent @acsfd
@c *libc_utmp_file_functions.setutent = setutent_file @mtasurace:utent @acsfd
@c open_not_cancel_2 dup @acsfd
@@ -1152,7 +1152,7 @@ A null pointer is returned in case no further entry is available.
@safety{@prelim{}@mtunsafe{@mtasurace{:utent}}@asunsafe{@asulock{}}@acunsafe{@aculock{} @acsfd{}}}
@c endutent @mtasurace:utent @asulock @aculock @acsfd
@c libc_lock_lock dup @asulock @aculock
-@c *libc_utmp_jump_table->endutent @mtasurace:utent @acsfd
+@c __libc_endutent @mtasurace:utent @acsfd
@c endutent_unknown ok
@c endutent_file @mtasurace:utent @acsfd
@c close_not_cancel_no_status dup @acsfd
@@ -1230,7 +1230,7 @@ over again.
@safety{@prelim{}@mtunsafe{@mtasurace{:utent} @mtascusig{:ALRM} @mtascutimer{}}@asunsafe{@asulock{}}@acunsafe{@aculock{} @acsfd{}}}
@c pututline @mtasurace:utent @mtascusig:ALRM @mtascutimer @asulock @aculock @acsfd
@c libc_lock_lock dup @asulock @aculock
-@c *libc_utmp_jump_table->pututline @mtasurace:utent @mtascusig:ALRM @mtascutimer @acsfd
+@c __libc_pututline @mtasurace:utent @mtascusig:ALRM @mtascutimer @acsfd
@c pututline_unknown @mtasurace:utent @acsfd
@c setutent_unknown dup @mtasurace:utent @acsfd
@c pututline_file @mtascusig:ALRM @mtascutimer @acsfd
@@ -1282,7 +1282,7 @@ user-provided buffer.
@safety{@prelim{}@mtunsafe{@mtasurace{:utent} @mtascusig{:ALRM} @mtascutimer{}}@asunsafe{@asulock{}}@acunsafe{@aculock{} @acsfd{}}}
@c getutent_r @mtasurace:utent @mtascusig:ALRM @mtascutimer @asulock @aculock @acsfd
@c libc_lock_lock dup @asulock @aculock
-@c *libc_utmp_jump_table->getutent_r @mtasurace:utent @mtascusig:ALRM @mtascutimer @acsfd
+@c __libc_getutent_r @mtasurace:utent @mtascusig:ALRM @mtascutimer @acsfd
@c getutent_r_unknown @mtasurace:utent @acsfd
@c setutent_unknown dup @mtasurace:utent @acsfd
@c getutent_r_file @mtasurace:utent @mtascusig:ALRM @mtascutimer
@@ -1319,7 +1319,7 @@ This function is a GNU extension.
@safety{@prelim{}@mtunsafe{@mtasurace{:utent} @mtascusig{:ALRM} @mtascutimer{}}@asunsafe{@asulock{}}@acunsafe{@aculock{} @acsfd{}}}
@c getutid_r @mtasurace:utent @mtascusig:ALRM @mtascutimer @asulock @aculock @acsfd
@c libc_lock_lock dup @asulock @aculock
-@c *libc_utmp_jump_table->getutid_r @mtasurace:utent @mtascusig:ALRM @mtascutimer @acsfd
+@c __libc_getutid_r @mtasurace:utent @mtascusig:ALRM @mtascutimer @acsfd
@c getutid_r_unknown @mtasurace:utent @acsfd
@c setutent_unknown dup @mtasurace:utent @acsfd
@c getutid_r_file @mtascusig:ALRM @mtascutimer
@@ -1349,7 +1349,7 @@ This function is a GNU extension.
@safety{@prelim{}@mtunsafe{@mtasurace{:utent} @mtascusig{:ALRM} @mtascutimer{}}@asunsafe{@asulock{}}@acunsafe{@aculock{} @acsfd{}}}
@c getutline_r @mtasurace:utent @mtascusig:ALRM @mtascutimer @asulock @aculock @acsfd
@c libc_lock_lock dup @asulock @aculock
-@c *libc_utmp_jump_table->getutline_r @mtasurace:utent @mtascusig:ALRM @mtascutimer @acsfd
+@c __libc_getutline_r @mtasurace:utent @mtascusig:ALRM @mtascutimer @acsfd
@c getutline_r_unknown @mtasurace:utent @acsfd
@c setutent_unknown dup @mtasurace:utent @acsfd
@c getutline_r_file @mtasurace:utent @mtascusig:ALRM @mtascutimer
@@ -1393,7 +1393,7 @@ be used.
@safety{@prelim{}@mtunsafe{@mtasurace{:utent}}@asunsafe{@asulock{} @ascuheap{}}@acunsafe{@aculock{} @acsmem{}}}
@c utmpname @mtasurace:utent @asulock @ascuheap @aculock @acsmem
@c libc_lock_lock dup @asulock @aculock
-@c *libc_utmp_jump_table->endutent dup @mtasurace:utent
+@c __libc_endutent dup @mtasurace:utent
@c strcmp dup ok
@c free dup @ascuheap @acsmem
@c strdup dup @ascuheap @acsmem
diff --git a/sysdeps/unix/getlogin_r.c b/sysdeps/unix/getlogin_r.c
index 6c564d3..88971a9 100644
--- a/sysdeps/unix/getlogin_r.c
+++ b/sysdeps/unix/getlogin_r.c
@@ -64,8 +64,8 @@ __getlogin_r (char *name, size_t name_len)
held so that our search is thread-safe. */
__libc_lock_lock (__libc_utmp_lock);
- (*__libc_utmp_jump_table->setutent) ();
- result = (*__libc_utmp_jump_table->getutline_r) (&line, &buffer, &ut);
+ __libc_setutent ();
+ result = __libc_getutline_r (&line, &buffer, &ut);
if (result < 0)
{
if (errno == ESRCH)
@@ -74,8 +74,7 @@ __getlogin_r (char *name, size_t name_len)
else
result = errno;
}
- (*__libc_utmp_jump_table->endutent) ();
- __libc_utmp_jump_table = &__libc_utmp_unknown_functions;
+ __libc_endutent ();
__libc_lock_unlock (__libc_utmp_lock);
if (result == 0)