[PATCH v4 0/7] Refactor syslog implementation

[PATCH v4 0/7] Refactor syslog implementation

[Adhemerval Zanella]

The main driver of this change is to move away of using 32-bit
timestamps.  Based on discussion where systemd should support
RFC5424 [1], it decided to move away from implementing on glibc [2]
and just replace the use of localtime by gmtime.  It is a deviation
from RFC3164, but it improves some corner cases [3].

[1] https://github.com/systemd/systemd/issues/19251
[2] https://sourceware.org/pipermail/libc-alpha/2022-February/136595.html
[3] https://sourceware.org/pipermail/libc-alpha/2021-March/123583.html

Adhemerval Zanella (7):
  support: Add xmkfifo
  misc: Add syslog test
  misc: syslog: Fix indentation and style
  misc: syslog: Simplify implementation
  misc: syslog: Use fixed-sized buffer and remove memstream
  misc: syslog: Move SYSLOG_NAME to USE_MISC (BZ #16355)
  misc: Use gmtime instead of localtime

 misc/Makefile     |   2 +
 misc/sys/syslog.h |   4 +-
 misc/syslog.c     | 477 ++++++++++++++++++++++------------------------
 misc/tst-syslog.c | 477 ++++++++++++++++++++++++++++++++++++++++++++++
 support/Makefile  |   1 +
 support/xmkfifo.c |  29 +++
 support/xunistd.h |   1 +
 7 files changed, 745 insertions(+), 246 deletions(-)
 create mode 100644 misc/tst-syslog.c
 create mode 100644 support/xmkfifo.c

-- 
2.32.0

[PATCH v4 1/7] support: Add xmkfifo

[Adhemerval Zanella]

Wrapper support mkfifo.
---
 support/Makefile  |  1 +
 support/xmkfifo.c | 29 +++++++++++++++++++++++++++++
 support/xunistd.h |  1 +
 3 files changed, 31 insertions(+)
 create mode 100644 support/xmkfifo.c

diff --git a/support/Makefile b/support/Makefile
index 5ddcb8d158..c3609e211b 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -133,6 +133,7 @@ libsupport-routines = \
   xmemstream \
   xmkdir \
   xmkdirp \
+  xmkfifo \
   xmmap \
   xmprotect \
   xmunmap \
diff --git a/support/xmkfifo.c b/support/xmkfifo.c
new file mode 100644
index 0000000000..a8e196dbc2
--- /dev/null
+++ b/support/xmkfifo.c
@@ -0,0 +1,29 @@
+/* mkfifo with error checking.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/xunistd.h>
+#include <sys/stat.h>
+
+void
+xmkfifo (const char *pathname, mode_t mode)
+{
+  int r = mkfifo (pathname, mode);
+  if (r < 0)
+    FAIL_EXIT1 ("mkfifo (%s, 0%o): %m", pathname, mode);
+}
diff --git a/support/xunistd.h b/support/xunistd.h
index 0454d83cf1..960a62d412 100644
--- a/support/xunistd.h
+++ b/support/xunistd.h
@@ -61,6 +61,7 @@ void xsymlink (const char *target, const char *linkpath);
 void xchdir (const char *path);
 void xfchmod (int fd, mode_t mode);
 void xchmod (const char *pathname, mode_t mode);
+void xmkfifo (const char *pathname, mode_t mode);
 
 /* Equivalent of "mkdir -p".  */
 void xmkdirp (const char *, mode_t);
-- 
2.32.0

[PATCH v4 2/7] misc: Add syslog test

[Adhemerval Zanella]

The test cover:

  - All possible priorities and facilities through TCP and UDP.
  - Same syslog tests for vsyslog.
  - Some openlog/syslog/close combinations.
  - openlog with LOG_CONS, LOG_PERROR, and LOG_PID.

Internally is done with a test-container where the main process mimics
the syslog server interface.

The test does not cover multithread and async-signal usage.

Checked on x86_64-linux-gnu.
---
 misc/Makefile     |   2 +
 misc/tst-syslog.c | 477 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 479 insertions(+)
 create mode 100644 misc/tst-syslog.c

diff --git a/misc/Makefile b/misc/Makefile
index 3d8a569d06..ba8232a0e9 100644
--- a/misc/Makefile
+++ b/misc/Makefile
@@ -115,6 +115,8 @@ tests-special += $(objpfx)tst-error1-mem.out \
   $(objpfx)tst-allocate_once-mem.out
 endif
 
+tests-container := tst-syslog
+
 CFLAGS-select.c += -fexceptions -fasynchronous-unwind-tables
 CFLAGS-tsearch.c += $(uses-callbacks)
 CFLAGS-lsearch.c += $(uses-callbacks)
diff --git a/misc/tst-syslog.c b/misc/tst-syslog.c
new file mode 100644
index 0000000000..8505178616
--- /dev/null
+++ b/misc/tst-syslog.c
@@ -0,0 +1,477 @@
+/* Basic tests for syslog interfaces.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <fcntl.h>
+#include <paths.h>
+#include <netinet/in.h>
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+#include <support/temp_file.h>
+#include <support/xstdio.h>
+#include <support/xsocket.h>
+#include <support/xunistd.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <syslog.h>
+#include <sys/un.h>
+
+static const int facilities[] =
+  {
+    LOG_KERN,
+    LOG_USER,
+    LOG_MAIL,
+    LOG_DAEMON,
+    LOG_AUTH,
+    LOG_SYSLOG,
+    LOG_LPR,
+    LOG_NEWS,
+    LOG_UUCP,
+    LOG_CRON,
+    LOG_AUTHPRIV,
+    LOG_FTP,
+    LOG_LOCAL0,
+    LOG_LOCAL1,
+    LOG_LOCAL2,
+    LOG_LOCAL3,
+    LOG_LOCAL4,
+    LOG_LOCAL5,
+    LOG_LOCAL6,
+    LOG_LOCAL7,
+  };
+
+static const int priorities[] =
+  {
+    LOG_EMERG,
+    LOG_ALERT,
+    LOG_CRIT,
+    LOG_ERR,
+    LOG_WARNING,
+    LOG_NOTICE,
+    LOG_INFO,
+    LOG_DEBUG
+  };
+
+enum
+  {
+    ident_length = 64,
+    msg_length = 64
+  };
+
+#define SYSLOG_MSG_BASE "syslog_message"
+#define OPENLOG_IDENT   "openlog_ident"
+
+struct msg_t
+  {
+    int priority;
+    int facility;
+    char ident[ident_length];
+    char msg[msg_length];
+    pid_t pid;
+  };
+
+static void
+call_vsyslog (int priority, const char *format, ...)
+{
+  va_list ap;
+  va_start (ap, format);
+  vsyslog (priority, format, ap);
+  va_end (ap);
+}
+
+static void
+send_vsyslog (int options)
+{
+  for (size_t i = 0; i < array_length (facilities); i++)
+    {
+      for (size_t j = 0; j < array_length (priorities); j++)
+        {
+          int facility = facilities[i];
+          int priority = priorities[j];
+          call_vsyslog (facility | priority, "%s %d %d", SYSLOG_MSG_BASE,
+                        facility, priority);
+        }
+    }
+}
+
+static void
+send_syslog (int options)
+{
+  for (size_t i = 0; i < array_length (facilities); i++)
+    {
+      for (size_t j = 0; j < array_length (priorities); j++)
+        {
+          int facility = facilities[i];
+          int priority = priorities[j];
+          syslog (facility | priority, "%s %d %d", SYSLOG_MSG_BASE, facility,
+                  priority);
+        }
+    }
+}
+
+static bool
+check_syslog_message (const struct msg_t *msg, int msgnum, int options,
+                      pid_t pid)
+{
+  if (msgnum == array_length (facilities) * array_length (priorities) - 1)
+    return false;
+
+  int i = msgnum / array_length (priorities);
+  int j = msgnum % array_length (priorities);
+
+  int expected_facility = facilities[i];
+  /* With no preceding openlog, syslog default to LOG_USER.  */
+  if (expected_facility == LOG_KERN)
+      expected_facility = LOG_USER;
+  int expected_priority = priorities[j];
+
+  TEST_COMPARE (msg->facility, expected_facility);
+  TEST_COMPARE (msg->priority, expected_priority);
+
+  return true;
+}
+
+static void
+send_openlog (int options)
+{
+  /* Define a non-default IDENT and a not default facility.  */
+  openlog (OPENLOG_IDENT, options, LOG_LOCAL0);
+  for (size_t j = 0; j < array_length (priorities); j++)
+    {
+      int priority = priorities[j];
+      syslog (priority, "%s %d %d", SYSLOG_MSG_BASE, LOG_LOCAL0, priority);
+    }
+  closelog ();
+
+  /* Back to the default IDENT with a non default facility.  */
+  openlog (NULL, 0, LOG_LOCAL6);
+  for (size_t j = 0; j < array_length (priorities); j++)
+    {
+      int priority = priorities[j];
+      syslog (LOG_LOCAL7 | priority, "%s %d %d", SYSLOG_MSG_BASE, LOG_LOCAL7,
+        priority);
+    }
+  closelog ();
+
+  /* LOG_KERN does not change the internal default facility.  */
+  openlog (NULL, 0, LOG_KERN);
+  for (size_t j = 0; j < array_length (priorities); j++)
+    {
+      int priority = priorities[j];
+      syslog (priority, "%s %d %d", SYSLOG_MSG_BASE, LOG_KERN, priority);
+    }
+  closelog ();
+}
+
+static bool
+check_openlog_message (const struct msg_t *msg, int msgnum,
+                       int options, pid_t pid)
+{
+  if (msgnum == 3 * array_length (priorities) - 1)
+    return false;
+
+  int expected_priority = priorities[msgnum % array_length (priorities)];
+  TEST_COMPARE (msg->priority, expected_priority);
+
+  char expected_ident[ident_length];
+  snprintf (expected_ident, sizeof (expected_ident), "%s%s%.0d%s:",
+            OPENLOG_IDENT,
+            options & LOG_PID ? "[" : "",
+            options & LOG_PID ? pid : 0,
+            options & LOG_PID ? "]" : "");
+
+  if (msgnum < array_length (priorities))
+    {
+      if (options & LOG_PID)
+        TEST_COMPARE (msg->pid, pid);
+      TEST_COMPARE_STRING (msg->ident, expected_ident);
+      TEST_COMPARE (msg->facility, LOG_LOCAL0);
+    }
+  else if (msgnum < 2 * array_length (priorities))
+    TEST_COMPARE (msg->facility, LOG_LOCAL7);
+  else if (msgnum < 3 * array_length (priorities))
+    TEST_COMPARE (msg->facility, LOG_KERN);
+
+  return true;
+}
+
+static struct msg_t
+parse_syslog_msg (const char *msg)
+{
+  struct msg_t r = { .pid = -1 };
+  int number;
+
+  /* The message in the form:
+     <179>Apr  8 14:51:19 tst-syslog: syslog message 176 3  */
+  int n = sscanf (msg, "<%3d>%*s %*d %*d:%*d:%*d %32s %64s %*d %*d",
+                  &number, r.ident, r.msg);
+  TEST_COMPARE (n, 3);
+
+  r.facility = number & LOG_FACMASK;
+  r.priority = number & LOG_PRIMASK;
+
+  char *pid_start = strchr (r.ident, '[');
+  if (pid_start != NULL)
+    {
+       char *pid_end = strchr (r.ident, ']');
+       if (pid_end != NULL)
+         r.pid = strtoul (pid_start + 1, NULL, 10);
+    }
+
+  return r;
+}
+
+static struct msg_t
+parse_syslog_console (const char *msg)
+{
+  int priority;
+  int facility;
+  struct msg_t r;
+
+  /* The message in the form:
+     openlog_ident: syslog_message 128 0  */
+  int n = sscanf (msg, "%32s %64s %d %d",
+      r.ident, r.msg, &facility, &priority);
+  TEST_COMPARE (n, 4);
+
+  r.facility = facility;
+  r.priority = priority;
+
+  return r;
+}
+
+static void
+check_syslog_udp (void (*syslog_send)(int), int options,
+                  bool (*syslog_check)(const struct msg_t *, int, int,
+                                       pid_t))
+{
+  struct sockaddr_un addr =
+    {
+      .sun_family = AF_UNIX,
+      .sun_path = _PATH_LOG
+    };
+
+  socklen_t addrlen = sizeof (addr);
+  int server_udp = xsocket (AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
+  xbind (server_udp, (struct sockaddr *) &addr, addrlen);
+
+  pid_t sender_pid = xfork ();
+  if (sender_pid == 0)
+    {
+      syslog_send (options);
+      _exit (0);
+    }
+
+  int msgnum = 0;
+  while (1)
+    {
+      char buf[512];
+      size_t l = xrecvfrom (server_udp, buf, sizeof (buf), 0,
+                            (struct sockaddr *) &addr, &addrlen);
+      buf[l] = '\0';
+
+      struct msg_t msg = parse_syslog_msg (buf);
+      if (!syslog_check (&msg, msgnum++, options, sender_pid))
+        break;
+     }
+
+  xclose (server_udp);
+
+  int status;
+  xwaitpid (sender_pid, &status, 0);
+  TEST_COMPARE (status, 0);
+
+  unlink (_PATH_LOG);
+}
+
+static void
+check_syslog_tcp (void (*syslog_send)(int), int options,
+                  bool (*syslog_check)(const struct msg_t *, int, int,
+                                       pid_t))
+{
+  struct sockaddr_un addr =
+    {
+      .sun_family = AF_UNIX,
+      .sun_path = _PATH_LOG
+    };
+  socklen_t addrlen = sizeof (addr);
+
+  int server_tcp = xsocket (AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
+  xbind (server_tcp, (struct sockaddr *) &addr, addrlen);
+  xlisten (server_tcp, 5);
+
+  pid_t sender_pid = xfork ();
+  if (sender_pid == 0)
+    {
+      syslog_send (options);
+      _exit (0);
+    }
+
+  int client_tcp = xaccept (server_tcp, NULL, NULL);
+
+  char buf[512], *rb = buf;
+  size_t rbl = sizeof (buf);
+  size_t prl = 0;  /* Track the size of the partial record.  */
+  int msgnum = 0;
+
+  while (1)
+    {
+      size_t rl = xrecvfrom (client_tcp, rb, rbl - prl, 0, NULL, NULL);
+      if (rl == 0)
+        break;
+
+      /* Iterate over the buffer to find and check the record.  */
+      size_t l = rl + prl;
+      char *b = buf;
+      while (1)
+	{
+          /* With TCP each record ends with a '\0'.  */
+          char *e = memchr (b, '\0', l);
+          if (e != NULL)
+            {
+              struct msg_t msg = parse_syslog_msg (b);
+              if (!syslog_check (&msg, msgnum++, options, sender_pid))
+                break;
+
+	      /* Advance to the next record.  */
+	      ptrdiff_t diff = e + 1 - b;
+	      b += diff;
+	      l -= diff;
+	    }
+	  else
+	    {
+              /* Move the partial record to the start of the buffer.  */
+	      memmove (buf, b, l);
+	      rb = buf + l;
+	      prl = l;
+	      break;
+            }
+        }
+    }
+
+  xclose (client_tcp);
+  xclose (server_tcp);
+
+  int status;
+  xwaitpid (sender_pid, &status, 0);
+  TEST_COMPARE (status, 0);
+
+  unlink (_PATH_LOG);
+}
+
+static void
+check_syslog_console_read (FILE *fp)
+{
+  char buf[512];
+  int msgnum = 0;
+  while (fgets (buf, sizeof (buf), fp) != NULL)
+    {
+      struct msg_t msg = parse_syslog_console (buf);
+      TEST_COMPARE_STRING (msg.ident, OPENLOG_IDENT ":");
+      TEST_COMPARE (msg.priority, priorities[msgnum]);
+      TEST_COMPARE (msg.facility, LOG_LOCAL0);
+
+      if (++msgnum == array_length (priorities))
+        break;
+    }
+}
+
+static void
+check_syslog_console (void)
+{
+  xmkfifo (_PATH_CONSOLE, 0666);
+
+  pid_t sender_pid = xfork ();
+  if (sender_pid == 0)
+    {
+      send_openlog (LOG_CONS);
+      _exit (0);
+    }
+
+  {
+    FILE *fp = xfopen (_PATH_CONSOLE, "r+");
+    check_syslog_console_read (fp);
+    xfclose (fp);
+  }
+
+  int status;
+  xwaitpid (sender_pid, &status, 0);
+  TEST_COMPARE (status, 0);
+
+  unlink (_PATH_CONSOLE);
+}
+
+static void
+send_openlog_callback (void *clousure)
+{
+  int options = *(int *) clousure;
+  send_openlog (options);
+}
+
+static void
+check_syslog_perror (void)
+{
+  struct support_capture_subprocess result;
+  result = support_capture_subprocess (send_openlog_callback,
+                                       &(int){LOG_PERROR});
+
+  FILE *mfp = fmemopen (result.err.buffer, result.err.length, "r");
+  if (mfp == NULL)
+    FAIL_EXIT1 ("fmemopen: %m");
+  check_syslog_console_read (mfp);
+  xfclose (mfp);
+
+  support_capture_subprocess_check (&result, "tst-openlog-child", 0,
+                                    sc_allow_stderr);
+  support_capture_subprocess_free (&result);
+}
+
+static int
+do_test (void)
+{
+  add_temp_file (_PATH_LOG);
+  add_temp_file (_PATH_CONSOLE);
+
+  /* Send every combination of facility/priority over UDP and TCP.  */
+  check_syslog_udp (send_syslog, 0, check_syslog_message);
+  check_syslog_tcp (send_syslog, 0, check_syslog_message);
+
+  /* Also check vsyslog.  */
+  check_syslog_udp (send_vsyslog, 0, check_syslog_message);
+  check_syslog_tcp (send_vsyslog, 0, check_syslog_message);
+
+  /* Run some openlog/syslog/closelog combinations.  */
+  check_syslog_udp (send_openlog, 0, check_openlog_message);
+  check_syslog_tcp (send_openlog, 0, check_openlog_message);
+
+  /* Check the LOG_PID option.  */
+  check_syslog_udp (send_openlog, LOG_PID, check_openlog_message);
+  check_syslog_tcp (send_openlog, LOG_PID, check_openlog_message);
+
+  /* Check the LOG_CONS option.  */
+  check_syslog_console ();
+
+  /* Check the LOG_PERROR option.  */
+  check_syslog_perror ();
+
+  return 0;
+}
+
+#include <support/test-driver.c>
-- 
2.32.0

[PATCH v4 3/7] misc: syslog: Fix indentation and style

[Adhemerval Zanella]

And also clenaup the headers, no semantic changes.
---
 misc/syslog.c | 471 ++++++++++++++++++++++++--------------------------
 1 file changed, 228 insertions(+), 243 deletions(-)

diff --git a/misc/syslog.c b/misc/syslog.c
index ee83b1bb76..0736459e7b 100644
--- a/misc/syslog.c
+++ b/misc/syslog.c
@@ -31,49 +31,33 @@
 static char sccsid[] = "@(#)syslog.c	8.4 (Berkeley) 3/18/94";
 #endif /* LIBC_SCCS and not lint */
 
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <sys/syslog.h>
-#include <sys/uio.h>
-#include <sys/un.h>
-#include <netdb.h>
-
-#include <errno.h>
-#include <fcntl.h>
+#include <libio/libioP.h>
 #include <paths.h>
+#include <stdarg.h>
+#include <stdlib.h>
 #include <stdio.h>
 #include <stdio_ext.h>
-#include <string.h>
-#include <time.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <libc-lock.h>
-#include <signal.h>
-#include <locale.h>
-
-#include <stdarg.h>
-
-#include <libio/libioP.h>
-#include <math_ldbl_opt.h>
-
-#include <kernel-features.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+#include <sys/un.h>
+#include <syslog.h>
 
 #define ftell(s) _IO_ftell (s)
 
-static int	LogType = SOCK_DGRAM;	/* type of socket connection */
-static int	LogFile = -1;		/* fd for log */
-static bool	connected;		/* have done connect */
-static int	LogStat;		/* status bits, set by openlog() */
+static int LogType = SOCK_DGRAM;	/* type of socket connection */
+static int LogFile = -1;		/* fd for log */
+static bool connected;			/* have done connect */
+static int LogStat;			/* status bits, set by openlog() */
 static const char *LogTag;		/* string to tag the entry with */
-static int	LogFacility = LOG_USER;	/* default facility code */
-static int	LogMask = 0xff;		/* mask of priorities to be logged */
-extern char	*__progname;		/* Program name, from crt0. */
+static int LogFacility = LOG_USER;	/* default facility code */
+static int LogMask = 0xff;		/* mask of priorities to be logged */
+extern char *__progname;		/* Program name, from crt0. */
 
 /* Define the lock.  */
 __libc_lock_define_initialized (static, syslog_lock)
 
-static void openlog_internal(const char *, int, int);
-static void closelog_internal(void);
+static void openlog_internal (const char *, int, int);
+static void closelog_internal (void);
 
 struct cleanup_arg
 {
@@ -101,205 +85,204 @@ cancel_handler (void *ptr)
  *	print message on log file; output is intended for syslogd(8).
  */
 void
-__syslog(int pri, const char *fmt, ...)
+__syslog (int pri, const char *fmt, ...)
 {
-	va_list ap;
+  va_list ap;
 
-	va_start(ap, fmt);
-	__vsyslog_internal(pri, fmt, ap, 0);
-	va_end(ap);
+  va_start (ap, fmt);
+  __vsyslog_internal (pri, fmt, ap, 0);
+  va_end (ap);
 }
 ldbl_hidden_def (__syslog, syslog)
 ldbl_strong_alias (__syslog, syslog)
 
 void
-__vsyslog(int pri, const char *fmt, va_list ap)
+__vsyslog (int pri, const char *fmt, va_list ap)
 {
-	__vsyslog_internal(pri, fmt, ap, 0);
+  __vsyslog_internal (pri, fmt, ap, 0);
 }
 ldbl_weak_alias (__vsyslog, vsyslog)
 
 void
-__syslog_chk(int pri, int flag, const char *fmt, ...)
+__syslog_chk (int pri, int flag, const char *fmt, ...)
 {
-	va_list ap;
+  va_list ap;
 
-	va_start(ap, fmt);
-	__vsyslog_internal(pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
-	va_end(ap);
+  va_start (ap, fmt);
+  __vsyslog_internal (pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
+  va_end (ap);
 }
 
 void
 __vsyslog_chk(int pri, int flag, const char *fmt, va_list ap)
 {
-	__vsyslog_internal(pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
+  __vsyslog_internal (pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
 }
 
 void
 __vsyslog_internal(int pri, const char *fmt, va_list ap,
 		   unsigned int mode_flags)
 {
-	struct tm now_tm;
-	time_t now;
-	int fd;
-	FILE *f;
-	char *buf = 0;
-	size_t bufsize = 0;
-	size_t msgoff;
-	int saved_errno = errno;
-	char failbuf[3 * sizeof (pid_t) + sizeof "out of memory []"];
-
-#define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
-	/* Check for invalid bits. */
-	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
-		syslog(INTERNALLOG,
-		    "syslog: unknown facility/priority: %x", pri);
-		pri &= LOG_PRIMASK|LOG_FACMASK;
+  struct tm now_tm;
+  time_t now;
+  int fd;
+  FILE *f;
+  char *buf = 0;
+  size_t bufsize = 0;
+  size_t msgoff;
+  int saved_errno = errno;
+  char failbuf[3 * sizeof (pid_t) + sizeof "out of memory []"];
+
+#define	INTERNALLOG LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
+  /* Check for invalid bits. */
+  if (pri & ~(LOG_PRIMASK|LOG_FACMASK))
+    {
+      syslog (INTERNALLOG, "syslog: unknown facility/priority: %x", pri);
+      pri &= LOG_PRIMASK|LOG_FACMASK;
+    }
+
+  /* Prepare for multiple users.  We have to take care: most syscalls we are
+     using are cancellation points.  */
+  struct cleanup_arg clarg;
+  clarg.buf = NULL;
+  clarg.oldaction = NULL;
+  __libc_cleanup_push (cancel_handler, &clarg);
+  __libc_lock_lock (syslog_lock);
+
+  /* Check priority against setlogmask values. */
+  if ((LOG_MASK (LOG_PRI (pri)) & LogMask) == 0)
+    goto out;
+
+  /* Set default facility if none specified. */
+  if ((pri & LOG_FACMASK) == 0)
+    pri |= LogFacility;
+
+  /* Build the message in a memory-buffer stream.  */
+  f = __open_memstream (&buf, &bufsize);
+  if (f == NULL)
+    {
+      /* We cannot get a stream.  There is not much we can do but emitting an
+	 error messages.  */
+      char numbuf[3 * sizeof (pid_t)];
+      char *nump;
+      char *endp = __stpcpy (failbuf, "out of memory [");
+      pid_t pid = __getpid ();
+
+      nump = numbuf + sizeof (numbuf);
+      /* The PID can never be zero.  */
+      do
+	*--nump = '0' + pid % 10;
+      while ((pid /= 10) != 0);
+
+      endp = __mempcpy (endp, nump, (numbuf + sizeof (numbuf)) - nump);
+      *endp++ = ']';
+      *endp = '\0';
+      buf = failbuf;
+      bufsize = endp - failbuf;
+      msgoff = 0;
+    }
+  else
+    {
+      __fsetlocking (f, FSETLOCKING_BYCALLER);
+      fprintf (f, "<%d>", pri);
+      now = time_now ();
+      f->_IO_write_ptr += __strftime_l (f->_IO_write_ptr,
+					f->_IO_write_end - f->_IO_write_ptr,
+					"%h %e %T ",
+					__localtime_r (&now, &now_tm),
+					_nl_C_locobj_ptr);
+      msgoff = ftell (f);
+      if (LogTag == NULL)
+	LogTag = __progname;
+      if (LogTag != NULL)
+	__fputs_unlocked (LogTag, f);
+      if (LogStat & LOG_PID)
+	fprintf (f, "[%d]", (int) __getpid ());
+      if (LogTag != NULL)
+	{
+	  __putc_unlocked (':', f);
+	  __putc_unlocked (' ', f);
 	}
 
-	/* Prepare for multiple users.  We have to take care: most
-	   syscalls we are using are cancellation points.  */
-	struct cleanup_arg clarg;
-	clarg.buf = NULL;
-	clarg.oldaction = NULL;
-	__libc_cleanup_push (cancel_handler, &clarg);
-	__libc_lock_lock (syslog_lock);
-
-	/* Check priority against setlogmask values. */
-	if ((LOG_MASK (LOG_PRI (pri)) & LogMask) == 0)
-		goto out;
-
-	/* Set default facility if none specified. */
-	if ((pri & LOG_FACMASK) == 0)
-		pri |= LogFacility;
-
-	/* Build the message in a memory-buffer stream.  */
-	f = __open_memstream (&buf, &bufsize);
-	if (f == NULL)
-	  {
-	    /* We cannot get a stream.  There is not much we can do but
-	       emitting an error messages.  */
-	    char numbuf[3 * sizeof (pid_t)];
-	    char *nump;
-	    char *endp = __stpcpy (failbuf, "out of memory [");
-	    pid_t pid = __getpid ();
-
-	    nump = numbuf + sizeof (numbuf);
-	    /* The PID can never be zero.  */
-	    do
-	      *--nump = '0' + pid % 10;
-	    while ((pid /= 10) != 0);
-
-	    endp = __mempcpy (endp, nump, (numbuf + sizeof (numbuf)) - nump);
-	    *endp++ = ']';
-	    *endp = '\0';
-	    buf = failbuf;
-	    bufsize = endp - failbuf;
-	    msgoff = 0;
-	  }
-	else
-	  {
-	    __fsetlocking (f, FSETLOCKING_BYCALLER);
-	    fprintf (f, "<%d>", pri);
-	    now = time_now ();
-	    f->_IO_write_ptr += __strftime_l (f->_IO_write_ptr,
-					      f->_IO_write_end
-					      - f->_IO_write_ptr,
-					      "%h %e %T ",
-					      __localtime_r (&now, &now_tm),
-					      _nl_C_locobj_ptr);
-	    msgoff = ftell (f);
-	    if (LogTag == NULL)
-	      LogTag = __progname;
-	    if (LogTag != NULL)
-	      __fputs_unlocked (LogTag, f);
-	    if (LogStat & LOG_PID)
-	      fprintf (f, "[%d]", (int) __getpid ());
-	    if (LogTag != NULL)
-	      {
-		__putc_unlocked (':', f);
-		__putc_unlocked (' ', f);
-	      }
-
-	    /* Restore errno for %m format.  */
-	    __set_errno (saved_errno);
-
-	    /* We have the header.  Print the user's format into the
-	       buffer.  */
-	    __vfprintf_internal (f, fmt, ap, mode_flags);
-
-	    /* Close the memory stream; this will finalize the data
-	       into a malloc'd buffer in BUF.  */
-	    fclose (f);
-
-	    /* Tell the cancellation handler to free this buffer.  */
-	    clarg.buf = buf;
-	  }
-
-	/* Output to stderr if requested. */
-	if (LogStat & LOG_PERROR) {
-		struct iovec iov[2];
-		struct iovec *v = iov;
-
-		v->iov_base = buf + msgoff;
-		v->iov_len = bufsize - msgoff;
-		/* Append a newline if necessary.  */
-		if (buf[bufsize - 1] != '\n')
-		  {
-		    ++v;
-		    v->iov_base = (char *) "\n";
-		    v->iov_len = 1;
-		  }
-
-		/* writev is a cancellation point.  */
-		(void)__writev(STDERR_FILENO, iov, v - iov + 1);
+      /* Restore errno for %m format.  */
+      __set_errno (saved_errno);
+
+      /* We have the header.  Print the user's format into the buffer.  */
+      __vfprintf_internal (f, fmt, ap, mode_flags);
+
+      /* Close the memory stream; this will finalize the data into a malloc'd
+	 buffer in BUF.  */
+      fclose (f);
+
+      /* Tell the cancellation handler to free this buffer.  */
+      clarg.buf = buf;
+    }
+
+  /* Output to stderr if requested. */
+  if (LogStat & LOG_PERROR)
+    {
+      struct iovec iov[2];
+      struct iovec *v = iov;
+
+      v->iov_base = buf + msgoff;
+      v->iov_len = bufsize - msgoff;
+      /* Append a newline if necessary.  */
+      if (buf[bufsize - 1] != '\n')
+	{
+	  ++v;
+	  v->iov_base = (char *) "\n";
+	  v->iov_len = 1;
+	}
+
+      /* writev is a cancellation point.  */
+      __writev (STDERR_FILENO, iov, v - iov + 1);
+    }
+
+  /* Get connected, output the message to the local logger.  */
+  if (!connected)
+    openlog_internal (NULL, LogStat | LOG_NDELAY, LogFacility);
+
+  /* If we have a SOCK_STREAM connection, also send ASCII NUL as a record
+     terminator.  */
+  if (LogType == SOCK_STREAM)
+    ++bufsize;
+
+  if (!connected || __send (LogFile, buf, bufsize, MSG_NOSIGNAL) < 0)
+    {
+      if (connected)
+	{
+	  /* Try to reopen the syslog connection.  Maybe it went down.  */
+	  closelog_internal ();
+	  openlog_internal (NULL, LogStat | LOG_NDELAY, LogFacility);
 	}
 
-	/* Get connected, output the message to the local logger. */
-	if (!connected)
-		openlog_internal(NULL, LogStat | LOG_NDELAY, LogFacility);
-
-	/* If we have a SOCK_STREAM connection, also send ASCII NUL as
-	   a record terminator.  */
-	if (LogType == SOCK_STREAM)
-	  ++bufsize;
-
-	if (!connected || __send(LogFile, buf, bufsize, MSG_NOSIGNAL) < 0)
-	  {
-	    if (connected)
-	      {
-		/* Try to reopen the syslog connection.  Maybe it went
-		   down.  */
-		closelog_internal ();
-		openlog_internal(NULL, LogStat | LOG_NDELAY, LogFacility);
-	      }
-
-	    if (!connected || __send(LogFile, buf, bufsize, MSG_NOSIGNAL) < 0)
-	      {
-		closelog_internal ();	/* attempt re-open next time */
-		/*
-		 * Output the message to the console; don't worry
-		 * about blocking, if console blocks everything will.
-		 * Make sure the error reported is the one from the
-		 * syslogd failure.
-		 */
-		if (LogStat & LOG_CONS &&
-		    (fd = __open(_PATH_CONSOLE, O_WRONLY|O_NOCTTY|O_CLOEXEC,
-				 0)) >= 0)
-		  {
-		    __dprintf (fd, "%s\r\n", buf + msgoff);
-		    (void)__close(fd);
-		  }
-	      }
-	  }
+      if (!connected || __send (LogFile, buf, bufsize, MSG_NOSIGNAL) < 0)
+	{
+	  closelog_internal ();	/* attempt re-open next time */
+	  /*
+	   * Output the message to the console; don't worry
+	   * about blocking, if console blocks everything will.
+	   * Make sure the error reported is the one from the
+	   * syslogd failure.
+	   */
+	  if (LogStat & LOG_CONS &&
+	      (fd = __open (_PATH_CONSOLE, O_WRONLY | O_NOCTTY
+			    | O_CLOEXEC, 0))
+	      >= 0)
+	    {
+	      __dprintf (fd, "%s\r\n", buf + msgoff);
+	      __close (fd);
+	    }
+	}
+    }
 
  out:
-	/* End of critical section.  */
-	__libc_cleanup_pop (0);
-	__libc_lock_unlock (syslog_lock);
+  /* End of critical section.  */
+  __libc_cleanup_pop (0);
+  __libc_lock_unlock (syslog_lock);
 
-	if (buf != failbuf)
-		free (buf);
+  if (buf != failbuf)
+    free (buf);
 }
 
 /* AF_UNIX address of local logger  */
@@ -312,45 +295,47 @@ static const struct sockaddr_un SyslogAddr =
 static void
 openlog_internal(const char *ident, int logstat, int logfac)
 {
-	if (ident != NULL)
-		LogTag = ident;
-	LogStat = logstat;
-	if ((logfac &~ LOG_FACMASK) == 0)
-		LogFacility = logfac;
-
-	int retry = 0;
-	while (retry < 2) {
-		if (LogFile == -1) {
-			if (LogStat & LOG_NDELAY) {
-			  LogFile = __socket(AF_UNIX, LogType | SOCK_CLOEXEC, 0);
-			  if (LogFile == -1)
-			    return;
-			}
-		}
-		if (LogFile != -1 && !connected)
+  if (ident != NULL)
+    LogTag = ident;
+  LogStat = logstat;
+  if ((logfac &~ LOG_FACMASK) == 0)
+    LogFacility = logfac;
+
+  int retry = 0;
+  while (retry < 2)
+    {
+      if (LogFile == -1)
+	{
+	  if (LogStat & LOG_NDELAY)
+	    {
+	      LogFile = __socket (AF_UNIX, LogType | SOCK_CLOEXEC, 0);
+	      if (LogFile == -1)
+		return;
+	    }
+	}
+      if (LogFile != -1 && !connected)
+	{
+	  int old_errno = errno;
+	  if (__connect (LogFile, &SyslogAddr, sizeof(SyslogAddr)) == -1)
+	    {
+	      int saved_errno = errno;
+	      int fd = LogFile;
+	      LogFile = -1;
+	      __close (fd);
+	      __set_errno (old_errno);
+	      if (saved_errno == EPROTOTYPE)
 		{
-			int old_errno = errno;
-			if (__connect(LogFile, &SyslogAddr, sizeof(SyslogAddr))
-			    == -1)
-			{
-				int saved_errno = errno;
-				int fd = LogFile;
-				LogFile = -1;
-				(void)__close(fd);
-				__set_errno (old_errno);
-				if (saved_errno == EPROTOTYPE)
-				{
-					/* retry with the other type: */
-					LogType = (LogType == SOCK_DGRAM
-						   ? SOCK_STREAM : SOCK_DGRAM);
-					++retry;
-					continue;
-				}
-			} else
-				connected = true;
+		  /* retry with the other type: */
+		  LogType = LogType == SOCK_DGRAM ? SOCK_STREAM : SOCK_DGRAM;
+		  ++retry;
+		  continue;
 		}
-		break;
+	    }
+	  else
+	    connected = true;
 	}
+      break;
+    }
 }
 
 void
@@ -395,16 +380,16 @@ closelog (void)
 int
 setlogmask (int pmask)
 {
-	int omask;
+  int omask;
 
-	/* Protect against multiple users.  */
-	__libc_lock_lock (syslog_lock);
+  /* Protect against multiple users.  */
+  __libc_lock_lock (syslog_lock);
 
-	omask = LogMask;
-	if (pmask != 0)
-		LogMask = pmask;
+  omask = LogMask;
+  if (pmask != 0)
+    LogMask = pmask;
 
-	__libc_lock_unlock (syslog_lock);
+  __libc_lock_unlock (syslog_lock);
 
-	return (omask);
+  return (omask);
 }
-- 
2.32.0

[PATCH v4 4/7] misc: syslog: Simplify implementation

[Adhemerval Zanella]

Use a temporary buffer for strftime instead of using internal libio
members, simplify fprintf call on the memstream and memory allocation,
use %b instead of %h, use dprintf instead of writev for LOG_PERROR.

Checked on x86_64-linux-gnu and i686-linux-gnu.
---
 misc/syslog.c | 93 ++++++++++++++-------------------------------------
 1 file changed, 26 insertions(+), 67 deletions(-)

diff --git a/misc/syslog.c b/misc/syslog.c
index 0736459e7b..20f46a76a2 100644
--- a/misc/syslog.c
+++ b/misc/syslog.c
@@ -123,13 +123,10 @@ void
 __vsyslog_internal(int pri, const char *fmt, va_list ap,
 		   unsigned int mode_flags)
 {
-  struct tm now_tm;
-  time_t now;
-  int fd;
   FILE *f;
   char *buf = 0;
   size_t bufsize = 0;
-  size_t msgoff;
+  int msgoff;
   int saved_errno = errno;
   char failbuf[3 * sizeof (pid_t) + sizeof "out of memory []"];
 
@@ -143,9 +140,7 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
 
   /* Prepare for multiple users.  We have to take care: most syscalls we are
      using are cancellation points.  */
-  struct cleanup_arg clarg;
-  clarg.buf = NULL;
-  clarg.oldaction = NULL;
+  struct cleanup_arg clarg = { NULL, NULL };
   __libc_cleanup_push (cancel_handler, &clarg);
   __libc_lock_lock (syslog_lock);
 
@@ -159,51 +154,22 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
 
   /* Build the message in a memory-buffer stream.  */
   f = __open_memstream (&buf, &bufsize);
-  if (f == NULL)
-    {
-      /* We cannot get a stream.  There is not much we can do but emitting an
-	 error messages.  */
-      char numbuf[3 * sizeof (pid_t)];
-      char *nump;
-      char *endp = __stpcpy (failbuf, "out of memory [");
-      pid_t pid = __getpid ();
-
-      nump = numbuf + sizeof (numbuf);
-      /* The PID can never be zero.  */
-      do
-	*--nump = '0' + pid % 10;
-      while ((pid /= 10) != 0);
-
-      endp = __mempcpy (endp, nump, (numbuf + sizeof (numbuf)) - nump);
-      *endp++ = ']';
-      *endp = '\0';
-      buf = failbuf;
-      bufsize = endp - failbuf;
-      msgoff = 0;
-    }
-  else
+  if (f != NULL)
     {
       __fsetlocking (f, FSETLOCKING_BYCALLER);
-      fprintf (f, "<%d>", pri);
-      now = time_now ();
-      f->_IO_write_ptr += __strftime_l (f->_IO_write_ptr,
-					f->_IO_write_end - f->_IO_write_ptr,
-					"%h %e %T ",
-					__localtime_r (&now, &now_tm),
-					_nl_C_locobj_ptr);
-      msgoff = ftell (f);
-      if (LogTag == NULL)
-	LogTag = __progname;
-      if (LogTag != NULL)
-	__fputs_unlocked (LogTag, f);
-      if (LogStat & LOG_PID)
-	fprintf (f, "[%d]", (int) __getpid ());
-      if (LogTag != NULL)
-	{
-	  __putc_unlocked (':', f);
-	  __putc_unlocked (' ', f);
-	}
-
+      /* "%b %e %H:%M:%S"  */
+      char timebuf[sizeof "MMM DD hh:mm:ss "];
+      time_t now = time_now ();
+      struct tm now_tm;
+      __localtime_r (&now, &now_tm);
+      __strftime_l (timebuf, sizeof (timebuf), "%b %e %T", &now_tm,
+		    _nl_C_locobj_ptr);
+
+      pid_t pid = LogStat & LOG_PID ? __getpid () : 0;
+
+      fprintf (f, "<%d>%s %n%s%s%.0d%s: ", pri, timebuf, &msgoff,
+               LogTag == NULL ? __progname : LogTag,
+               pid != 0 ? "[" : "", pid, pid != 0 ? "]" : "");
       /* Restore errno for %m format.  */
       __set_errno (saved_errno);
 
@@ -217,26 +183,18 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
       /* Tell the cancellation handler to free this buffer.  */
       clarg.buf = buf;
     }
+  else
+    {
+      /* Nothing much to do but emit an error message.  */
+      bufsize = __snprintf (failbuf, sizeof failbuf, "out of memory[%d]",
+                            __getpid ());
+      buf = failbuf;
+    }
 
   /* Output to stderr if requested. */
   if (LogStat & LOG_PERROR)
-    {
-      struct iovec iov[2];
-      struct iovec *v = iov;
-
-      v->iov_base = buf + msgoff;
-      v->iov_len = bufsize - msgoff;
-      /* Append a newline if necessary.  */
-      if (buf[bufsize - 1] != '\n')
-	{
-	  ++v;
-	  v->iov_base = (char *) "\n";
-	  v->iov_len = 1;
-	}
-
-      /* writev is a cancellation point.  */
-      __writev (STDERR_FILENO, iov, v - iov + 1);
-    }
+    __dprintf (STDERR_FILENO, "%s%s", buf + msgoff,
+	       "\n" + (buf[bufsize - 1] == '\n'));
 
   /* Get connected, output the message to the local logger.  */
   if (!connected)
@@ -265,6 +223,7 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
 	   * Make sure the error reported is the one from the
 	   * syslogd failure.
 	   */
+	  int fd;
 	  if (LogStat & LOG_CONS &&
 	      (fd = __open (_PATH_CONSOLE, O_WRONLY | O_NOCTTY
 			    | O_CLOEXEC, 0))
-- 
2.32.0

[PATCH v4 5/7] misc: syslog: Use fixed-sized buffer and remove memstream

[Adhemerval Zanella]

A fixed-sized buffer is used instead of memstream for messages up to
1024 bytes to avoid the potential BUFSIZ (8K) malloc and free for
each syslog call.

Also, since the buffer size is know, memstream is replaced with a
malloced buffer for larger messages.

Checked on x86_64-linux-gnu.
---
 misc/syslog.c | 86 +++++++++++++++++++++++++++++++--------------------
 1 file changed, 52 insertions(+), 34 deletions(-)

diff --git a/misc/syslog.c b/misc/syslog.c
index 20f46a76a2..b184b15eea 100644
--- a/misc/syslog.c
+++ b/misc/syslog.c
@@ -123,12 +123,12 @@ void
 __vsyslog_internal(int pri, const char *fmt, va_list ap,
 		   unsigned int mode_flags)
 {
-  FILE *f;
-  char *buf = 0;
+  /* Try to use a static buffer as an optimization.  */
+  char bufs[1024];
+  char *buf = NULL;
   size_t bufsize = 0;
   int msgoff;
   int saved_errno = errno;
-  char failbuf[3 * sizeof (pid_t) + sizeof "out of memory []"];
 
 #define	INTERNALLOG LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
   /* Check for invalid bits. */
@@ -152,43 +152,61 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
   if ((pri & LOG_FACMASK) == 0)
     pri |= LogFacility;
 
-  /* Build the message in a memory-buffer stream.  */
-  f = __open_memstream (&buf, &bufsize);
-  if (f != NULL)
+  pid_t pid = LogStat & LOG_PID ? __getpid () : 0;
+
+  /* "%b %e %H:%M:%S "  */
+  char timestamp[sizeof "MMM DD hh:mm:ss "];
+  time_t now = time_now ();
+  struct tm now_tm;
+  __localtime_r (&now, &now_tm);
+  __strftime_l (timestamp, sizeof timestamp, "%b %e %T ", &now_tm,
+                _nl_C_locobj_ptr);
+
+#define SYSLOG_HEADER(__pri, __timestamp, __msgoff, pid) \
+  "<%d>%s %n%s%s%.0d%s: ",                               \
+  __pri, __timestamp, __msgoff,                          \
+  LogTag == NULL ? __progname : LogTag,                  \
+  "[" + (pid == 0), pid, "]" + (pid == 0)
+
+  int l = __snprintf (bufs, sizeof bufs,
+                      SYSLOG_HEADER (pri, timestamp, &msgoff, pid));
+  if (0 <= l && l < sizeof bufs)
     {
-      __fsetlocking (f, FSETLOCKING_BYCALLER);
-      /* "%b %e %H:%M:%S"  */
-      char timebuf[sizeof "MMM DD hh:mm:ss "];
-      time_t now = time_now ();
-      struct tm now_tm;
-      __localtime_r (&now, &now_tm);
-      __strftime_l (timebuf, sizeof (timebuf), "%b %e %T", &now_tm,
-		    _nl_C_locobj_ptr);
-
-      pid_t pid = LogStat & LOG_PID ? __getpid () : 0;
-
-      fprintf (f, "<%d>%s %n%s%s%.0d%s: ", pri, timebuf, &msgoff,
-               LogTag == NULL ? __progname : LogTag,
-               pid != 0 ? "[" : "", pid, pid != 0 ? "]" : "");
+      va_list apc;
+      va_copy (apc, ap);
+
       /* Restore errno for %m format.  */
       __set_errno (saved_errno);
 
-      /* We have the header.  Print the user's format into the buffer.  */
-      __vfprintf_internal (f, fmt, ap, mode_flags);
-
-      /* Close the memory stream; this will finalize the data into a malloc'd
-	 buffer in BUF.  */
-      fclose (f);
+      int vl = __vsnprintf_internal (bufs + l, sizeof bufs - l, fmt, apc,
+                                     mode_flags);
+      if (0 <= vl && vl < sizeof bufs - l)
+        {
+          buf = bufs;
+          bufsize = l + vl;
+        }
 
-      /* Tell the cancellation handler to free this buffer.  */
-      clarg.buf = buf;
+      va_end (apc);
     }
-  else
+
+  if (buf == NULL)
     {
-      /* Nothing much to do but emit an error message.  */
-      bufsize = __snprintf (failbuf, sizeof failbuf, "out of memory[%d]",
-                            __getpid ());
-      buf = failbuf;
+      buf = malloc (l * sizeof (char));
+      if (buf != NULL)
+	{
+	  /* Tell the cancellation handler to free this buffer.  */
+	  clarg.buf = buf;
+
+	  __snprintf (buf, sizeof buf,
+		      SYSLOG_HEADER (pri, timestamp, &msgoff, pid));
+	}
+      else
+        {
+	  /* Nothing much to do but emit an error message.  */
+          bufsize = __snprintf (bufs, sizeof bufs,
+                                "out of memory[%d]", __getpid ());
+          buf = bufs;
+        }
     }
 
   /* Output to stderr if requested. */
@@ -240,7 +258,7 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
   __libc_cleanup_pop (0);
   __libc_lock_unlock (syslog_lock);
 
-  if (buf != failbuf)
+  if (buf != bufs)
     free (buf);
 }
 
-- 
2.32.0

[PATCH v4 6/7] misc: syslog: Move SYSLOG_NAME to USE_MISC (BZ #16355)

[Adhemerval Zanella]

There is no easy solution as described on first comment in bug report,
and some code (like busybox) assumes facilitynames existance when
SYSLOG_NAMES is defined (so we can't just remove it as suggested in
comment #2).

So use the easier solution and guard it with __USE_MISC.
---
 misc/sys/syslog.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/misc/sys/syslog.h b/misc/sys/syslog.h
index dc3b0e7ef8..d933fea104 100644
--- a/misc/sys/syslog.h
+++ b/misc/sys/syslog.h
@@ -62,7 +62,7 @@
 #define	LOG_PRI(p)	((p) & LOG_PRIMASK)
 #define	LOG_MAKEPRI(fac, pri)	((fac) | (pri))
 
-#ifdef SYSLOG_NAMES
+#if defined SYSLOG_NAMES && defined __USE_MISC
 #define	INTERNAL_NOPRI	0x10	/* the "no priority" priority */
 				/* mark "facility" */
 #define	INTERNAL_MARK	LOG_MAKEPRI(LOG_NFACILITIES << 3, 0)
@@ -118,7 +118,7 @@ CODE prioritynames[] =
 				/* facility of pri */
 #define	LOG_FAC(p)	(((p) & LOG_FACMASK) >> 3)
 
-#ifdef SYSLOG_NAMES
+#if defined SYSLOG_NAMES && defined __USE_MISC
 CODE facilitynames[] =
   {
     { "auth", LOG_AUTH },
-- 
2.32.0

[PATCH v4 7/7] misc: Use gmtime instead of localtime

[Adhemerval Zanella]

We deviate from RFC3164 which states timestamp should be in localtime
because although our __localtime_r does not set tzname, the relay still
might still use localtime (which does) and if the server timezone changes
it might result in wrong timestamp from client.  It still does not help
if a process switches its TZ setting from a timezone that has leap
seconds, to one that doesn't (or vice versa), but this would incur in
other problems.

It also handles the highly unlikely case where gmtime might return NULL,
in this case only the PRI is set to hopefully instruct the relay to
get eh TIMESTAMP (as defined by the RFC).

Finally it also uses internally the 64 bit time_t interfaces (to avoid
y2038 issues on 32 bit legacy architectures).

Checked on x86_64-linux-gnu and i686-linux-gnu.
---
 misc/syslog.c | 43 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/misc/syslog.c b/misc/syslog.c
index b184b15eea..62a69cf41a 100644
--- a/misc/syslog.c
+++ b/misc/syslog.c
@@ -156,11 +156,26 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
 
   /* "%b %e %H:%M:%S "  */
   char timestamp[sizeof "MMM DD hh:mm:ss "];
-  time_t now = time_now ();
+  __time64_t now = time64_now ();
+
+  /* Deviate from RFC3164 which states timestamp should be in localtime
+     because although  __localtime_r does not set tzname, the relay might
+     still use localtime (which does) and if the server timezone changes
+     it might result in wrong timestamp from client.  It still does not help
+     if a process switches its TZ setting from a timezone that has leap
+     seconds, to one that doesn't (or vice versa), but this would incur in
+     other problems as well.  */
   struct tm now_tm;
-  __localtime_r (&now, &now_tm);
-  __strftime_l (timestamp, sizeof timestamp, "%b %e %T ", &now_tm,
-                _nl_C_locobj_ptr);
+  struct tm *now_tmp = __gmtime64_r (&now, &now_tm);
+  bool has_ts = now_tmp != NULL;
+
+  /* In the unlikely case of gmtime_r failure (tm_year out of int range)
+     skip the hostname so the message is handled as valid PRI but without
+     TIMESTAMP or invalid TIMESTAMP (which should force the relay to add the
+     timestamp itself).  */
+  if (has_ts)
+    __strftime_l (timestamp, sizeof timestamp, "%h %e %T ", now_tmp,
+		  _nl_C_locobj_ptr);
 
 #define SYSLOG_HEADER(__pri, __timestamp, __msgoff, pid) \
   "<%d>%s %n%s%s%.0d%s: ",                               \
@@ -168,8 +183,16 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
   LogTag == NULL ? __progname : LogTag,                  \
   "[" + (pid == 0), pid, "]" + (pid == 0)
 
-  int l = __snprintf (bufs, sizeof bufs,
-                      SYSLOG_HEADER (pri, timestamp, &msgoff, pid));
+#define SYSLOG_HEADER_WITHOUT_TS(__pri, __msgoff)        \
+  "<%d>: %n", __pri, __msgoff
+
+  int l;
+  if (has_ts)
+    l = __snprintf (bufs, sizeof bufs,
+		    SYSLOG_HEADER (pri, timestamp, &msgoff, pid));
+  else
+    l = __snprintf (bufs, sizeof bufs,
+		    SYSLOG_HEADER_WITHOUT_TS (pri, &msgoff));
   if (0 <= l && l < sizeof bufs)
     {
       va_list apc;
@@ -197,8 +220,12 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
 	  /* Tell the cancellation handler to free this buffer.  */
 	  clarg.buf = buf;
 
-	  __snprintf (buf, sizeof buf,
-		      SYSLOG_HEADER (pri, timestamp, &msgoff, pid));
+	  if (has_ts)
+	    __snprintf (bufs, sizeof bufs,
+			SYSLOG_HEADER (pri, timestamp, &msgoff, pid));
+	  else
+	    __snprintf (bufs, sizeof bufs,
+			SYSLOG_HEADER_WITHOUT_TS (pri, &msgoff));
 	}
       else
         {
-- 
2.32.0

Re: [PATCH v4 0/7] Refactor syslog implementation

[Paul Eggert]

Thanks for the updates. This all looks good to me.

Re: [PATCH v4 0/7] Refactor syslog implementation

[Adhemerval Zanella]

On 21/03/2022 14:58, Paul Eggert wrote:
> Thanks for the updates. This all looks good to me.

Thanks for checking on this Paul.  Recently on systemd discussion [1], it seems
that using gmtime without embedding timezone displacement would potentially 
cause regression.  So I will send another version that just fix the y2038 
issue while keeping using localtime.

[1] https://github.com/systemd/systemd/issues/19251