Re: log files and permissions

Itagaki Takahiro wrote:
> I think the patch is almost ready for committer except the following
> three issues:
>
> 2010/7/13 Fujii Masao <masao.fujii@gmail.com>:
>>> +     if (!*value || *endptr || file_mode < 0 || file_mode > 0777)
>> The sticky bit cannot be set via log_file_mode. Is this intentional?

Yes -- I don't think there is a use case for sticky or setuid bits on log
files, even allowing execute is questionable.

> We should also check the value not to be something like 0699.
> How about checking it with (file_mode & ~0666) != 0 ?

Aha, that would ensure that the execute bit is not specified. Works for me.
The 0699 and other invalid octal values are caught by strtol()

>>> +#ifndef WIN32
>>> +             chmod(filename, Log_file_mode);
>>> +#endif
>> Don't we need to check the return value of chmod()?
>
> I prefer umask() rather than chmod() here.
>

Converted to umask()

>>> +const char *show_log_file_mode(void);
>> You forgot to write the show_log_file_mode()? I was not able to find that
>> in the patch.
>
> I want show_log_file_mode to print the setting value in octal format.
>

I've now (re)added the show_log_file_mode(). It used to be there, but then
at some point I decided to display the value "as-is".

While going through it, I moved the _setmode() call for win32 to logfile_open().

regards,
Martin

*** a/doc/src/sgml/config.sgml
--- b/doc/src/sgml/config.sgml
***************
*** 2789,2794 **** local0.*    /var/log/postgresql
--- 2789,2815 ----
        </listitem>
       </varlistentry>

+      <varlistentry id="guc-log-file-mode" xreflabel="log_file_mode">
+       <term><varname>log_file_mode</varname> (<type>integer</type>)</term>
+       <indexterm>
+        <primary><varname>log_file_mode</> configuration parameter</primary>
+       </indexterm>
+       <listitem>
+        <para>
+         On Unix systems this parameter sets the permissions for log files
+         when <varname>logging_collector</varname> is enabled. On Microsoft
+         Windows the file mode will be ignored. The value is an octal number
+         consisting of 3 digits signifying the permissions for the user, group
+         and others. Specifying execute permissions for log files results in
+         an error.
+        </para>
+        <para>
+         This parameter can only be set in the <filename>postgresql.conf</>
+         file or on the server command line.
+        </para>
+       </listitem>
+      </varlistentry>
+
       <varlistentry id="guc-log-rotation-age" xreflabel="log_rotation_age">
        <term><varname>log_rotation_age</varname> (<type>integer</type>)</term>
        <indexterm>
*** a/src/backend/commands/variable.c
--- b/src/backend/commands/variable.c
***************
*** 914,916 **** show_role(void)
--- 914,956 ----

      return endptr + 1;
  }
+
+
+ /*
+  * LOG_FILE_MODE
+  */
+
+ extern int Log_file_mode;        /* in guc.c */
+
+ /*
+  * assign_log_file_mode: GUC assign_hook for log_file_mode
+  */
+ const char *
+ assign_log_file_mode(const char *value, bool doit, GucSource source)
+ {
+     char *endptr;
+     long file_mode = strtol(value, &endptr, 8);
+
+     if (!*value || *endptr || file_mode < 0 || (file_mode & ~0666) != 0)
+     {
+         ereport(GUC_complaint_elevel(source),
+                 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+                  errmsg("invalid value for parameter \"log_file_mode\""),
+                  errhint("value must be a 3 digit octal number, with the execute bit not set")));
+         return NULL;
+     }
+
+     if (doit)
+         Log_file_mode = (int) file_mode;
+
+     return value;
+ }
+
+ const char *
+ show_log_file_mode(void)
+ {
+     static char buf[5];
+
+     snprintf(buf, sizeof(buf), "%04o", Log_file_mode);
+     return buf;
+ }
*** a/src/backend/postmaster/syslogger.c
--- b/src/backend/postmaster/syslogger.c
***************
*** 73,78 **** int            Log_RotationSize = 10 * 1024;
--- 73,79 ----
  char       *Log_directory = NULL;
  char       *Log_filename = NULL;
  bool        Log_truncate_on_rotation = false;
+ int            Log_file_mode = 0600;

  /*
   * Globally visible state (used by elog.c)
***************
*** 135,140 **** static void syslogger_parseArgs(int argc, char *argv[]);
--- 136,142 ----
  static void process_pipe_input(char *logbuffer, int *bytes_in_logbuffer);
  static void flush_pipe_input(char *logbuffer, int *bytes_in_logbuffer);
  static void open_csvlogfile(void);
+ static FILE *logfile_open(const char *filename, const char *mode, bool am_rotating);

  #ifdef WIN32
  static unsigned int __stdcall pipeThread(void *arg);
***************
*** 516,530 **** SysLogger_Start(void)
       */
      filename = logfile_getname(time(NULL), NULL);

!     syslogFile = fopen(filename, "a");
!
!     if (!syslogFile)
!         ereport(FATAL,
!                 (errcode_for_file_access(),
!                  (errmsg("could not create log file \"%s\": %m",
!                          filename))));
!
!     setvbuf(syslogFile, NULL, LBF_MODE, 0);

      pfree(filename);

--- 518,524 ----
       */
      filename = logfile_getname(time(NULL), NULL);

!     syslogFile = logfile_open(filename, "a", false);

      pfree(filename);

***************
*** 1004,1027 **** open_csvlogfile(void)

      filename = logfile_getname(time(NULL), ".csv");

!     fh = fopen(filename, "a");

!     if (!fh)
!         ereport(FATAL,
!                 (errcode_for_file_access(),
!                  (errmsg("could not create log file \"%s\": %m",
!                          filename))));

!     setvbuf(fh, NULL, LBF_MODE, 0);

! #ifdef WIN32
!     _setmode(_fileno(fh), _O_TEXT);        /* use CRLF line endings on Windows */
! #endif

!     csvlogFile = fh;

!     pfree(filename);

  }

  /*
--- 998,1050 ----

      filename = logfile_getname(time(NULL), ".csv");

!     fh = logfile_open(filename, "a", false);

!     csvlogFile = fh;

!     pfree(filename);

! }

! /*
!  * Open the logfile with proper permissions and buffering options.
!  *
!  * We ignore any errors if the logfile is opened as part of log rotation. In
!  * other cases the errors are treated as fatal.
!  */
! static FILE *
! logfile_open(const char *filename, const char *mode, bool am_rotating)
! {
!     mode_t    oumask;
!     FILE   *fh;

!     oumask = umask((mode_t) (~Log_file_mode & 0777));
!     fh = fopen(filename, mode);
!     umask(oumask);
!
!     if (fh)
!     {
!         setvbuf(fh, NULL, LBF_MODE, 0);

+ #ifdef WIN32
+         _setmode(_fileno(fh), _O_TEXT); /* use CRLF line endings on Windows */
+ #endif
+     }
+     else
+     {
+         if (am_rotating)
+             ereport(LOG,
+                     (errcode_for_file_access(),
+                      errmsg("could not create new log file \"%s\": %m",
+                              filename)));
+         else
+             ereport(FATAL,
+                     (errcode_for_file_access(),
+                      errmsg("could not create log file \"%s\": %m",
+                              filename)));
+     }
+
+     return fh;
  }

  /*
***************
*** 1070,1088 **** logfile_rotate(bool time_based_rotation, int size_rotation_for)
          if (Log_truncate_on_rotation && time_based_rotation &&
              last_file_name != NULL &&
              strcmp(filename, last_file_name) != 0)
!             fh = fopen(filename, "w");
          else
!             fh = fopen(filename, "a");

          if (!fh)
          {
              int            saveerrno = errno;

-             ereport(LOG,
-                     (errcode_for_file_access(),
-                      errmsg("could not open new log file \"%s\": %m",
-                             filename)));
-
              /*
               * ENFILE/EMFILE are not too surprising on a busy system; just
               * keep using the old file till we manage to get a new one.
--- 1093,1106 ----
          if (Log_truncate_on_rotation && time_based_rotation &&
              last_file_name != NULL &&
              strcmp(filename, last_file_name) != 0)
!             fh = logfile_open(filename, "w", true);
          else
!             fh = logfile_open(filename, "a", true);

          if (!fh)
          {
              int            saveerrno = errno;

              /*
               * ENFILE/EMFILE are not too surprising on a busy system; just
               * keep using the old file till we manage to get a new one.
***************
*** 1104,1115 **** logfile_rotate(bool time_based_rotation, int size_rotation_for)
              return;
          }

-         setvbuf(fh, NULL, LBF_MODE, 0);
-
- #ifdef WIN32
-         _setmode(_fileno(fh), _O_TEXT); /* use CRLF line endings on Windows */
- #endif
-
          fclose(syslogFile);
          syslogFile = fh;

--- 1122,1127 ----
***************
*** 1128,1146 **** logfile_rotate(bool time_based_rotation, int size_rotation_for)
          if (Log_truncate_on_rotation && time_based_rotation &&
              last_csv_file_name != NULL &&
              strcmp(csvfilename, last_csv_file_name) != 0)
!             fh = fopen(csvfilename, "w");
          else
!             fh = fopen(csvfilename, "a");

          if (!fh)
          {
              int            saveerrno = errno;

-             ereport(LOG,
-                     (errcode_for_file_access(),
-                      errmsg("could not open new log file \"%s\": %m",
-                             csvfilename)));
-
              /*
               * ENFILE/EMFILE are not too surprising on a busy system; just
               * keep using the old file till we manage to get a new one.
--- 1140,1153 ----
          if (Log_truncate_on_rotation && time_based_rotation &&
              last_csv_file_name != NULL &&
              strcmp(csvfilename, last_csv_file_name) != 0)
!             fh = logfile_open(csvfilename, "w", true);
          else
!             fh = logfile_open(csvfilename, "a", true);

          if (!fh)
          {
              int            saveerrno = errno;

              /*
               * ENFILE/EMFILE are not too surprising on a busy system; just
               * keep using the old file till we manage to get a new one.
***************
*** 1162,1173 **** logfile_rotate(bool time_based_rotation, int size_rotation_for)
              return;
          }

-         setvbuf(fh, NULL, LBF_MODE, 0);
-
- #ifdef WIN32
-         _setmode(_fileno(fh), _O_TEXT); /* use CRLF line endings on Windows */
- #endif
-
          fclose(csvlogFile);
          csvlogFile = fh;

--- 1169,1174 ----
*** a/src/backend/utils/misc/guc.c
--- b/src/backend/utils/misc/guc.c
***************
*** 412,417 **** static char *server_version_string;
--- 412,418 ----
  static int    server_version_num;
  static char *timezone_string;
  static char *log_timezone_string;
+ static char *log_file_mode_string;
  static char *timezone_abbreviations_string;
  static char *XactIsoLevel_string;
  static char *data_directory;
***************
*** 2243,2248 **** static struct config_string ConfigureNamesString[] =
--- 2244,2258 ----
      },

      {
+         {"log_file_mode", PGC_SIGHUP, LOGGING_WHERE,
+             gettext_noop("Sets the file permissions for log files."),
+             NULL
+         },
+         &log_file_mode_string,
+         "0600", assign_log_file_mode, show_log_file_mode
+     },
+
+     {
          {"DateStyle", PGC_USERSET, CLIENT_CONN_LOCALE,
              gettext_noop("Sets the display format for date and time values."),
              gettext_noop("Also controls interpretation of ambiguous "
*** a/src/backend/utils/misc/postgresql.conf.sample
--- b/src/backend/utils/misc/postgresql.conf.sample
***************
*** 265,270 ****
--- 265,271 ----
                      # can be absolute or relative to PGDATA
  #log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'    # log file name pattern,
                      # can include strftime() escapes
+ #log_file_mode = 0600            # creation mode for log files, octal
  #log_truncate_on_rotation = off        # If on, an existing log file of the
                      # same name as the new log file will be
                      # truncated rather than appended to.
*** a/src/include/commands/variable.h
--- b/src/include/commands/variable.h
***************
*** 35,39 **** extern const char *show_role(void);
--- 35,42 ----
  extern const char *assign_session_authorization(const char *value,
                               bool doit, GucSource source);
  extern const char *show_session_authorization(void);
+ const char *assign_log_file_mode(const char *value,
+                             bool doit, GucSource source);
+ const char *show_log_file_mode(void);

  #endif   /* VARIABLE_H */
*** a/src/include/postmaster/syslogger.h
--- b/src/include/postmaster/syslogger.h
***************
*** 68,73 **** extern int    Log_RotationSize;
--- 68,74 ----
  extern PGDLLIMPORT char *Log_directory;
  extern PGDLLIMPORT char *Log_filename;
  extern bool Log_truncate_on_rotation;
+ extern int Log_file_mode;

  extern bool am_syslogger;