postgrespro.git / summary / log / commit / refs

commit    276d2e6c2d8141f194a26da03b5b79375eb7041b
Author:   Michael Paquier <michael@paquier.xyz>
Date:     Sun Mar 24 12:00:35 2019 +0000

    Make current_logfiles use permissions assigned to files in data directory
    
    Since its introduction in 19dc233c, current_logfiles has been assigned
    the same permissions as a log file, which can be enforced with
    log_file_mode.  This setup can lead to incompatibility problems with
    group access permissions as current_logfiles is not located in the log
    directory, but at the root of the data folder.  Hence, if group
    permissions are used but log_file_mode is more restrictive, a backup
    with a user in the group having read access could fail even if the log
    directory is located outside of the data folder.
    
    Per discussion with the folks mentioned below, we have concluded that
    current_logfiles should not be treated as a log file as it only stores
    metadata related to log files, and that it should use the same
    permissions as all other files in the data directory.  This solution has
    the merit to be simple and fixes all the interaction problems between
    group access and log_file_mode.
    
    Author: Haribabu Kommi
    Reviewed-by: Stephen Frost, Robert Haas, Tom Lane, Michael Paquier
    Discussion: https://postgr.es/m/CAJrrPGcEotF1P7AWoeQyD3Pqr-0xkQg_Herv98DjbaMj+naozw@mail.gmail.com
    Backpatch-through: 11, where group access has been added.


 src/backend/postmaster/syslogger.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index d1ea46deb8..a471832086 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -31,6 +31,7 @@
 #include <sys/stat.h>
 #include <sys/time.h>
 
+#include "common/file_perm.h"
 #include "lib/stringinfo.h"
 #include "libpq/pqsignal.h"
 #include "miscadmin.h"
@@ -1447,12 +1448,14 @@ set_next_rotation_time(void)
  * log messages.  Useful for finding the name(s) of the current log file(s)
  * when there is time-based logfile rotation.  Filenames are stored in a
  * temporary file and which is renamed into the final destination for
- * atomicity.
+ * atomicity.  The file is opened with the same permissions as what gets
+ * created in the data directory and has proper buffering options.
  */
 static void
 update_metainfo_datafile(void)
 {
 	FILE	   *fh;
+	mode_t		oumask;
 
 	if (!(Log_destination & LOG_DESTINATION_STDERR) &&
 		!(Log_destination & LOG_DESTINATION_CSVLOG))
@@ -1465,7 +1468,21 @@ update_metainfo_datafile(void)
 		return;
 	}
 
-	if ((fh = logfile_open(LOG_METAINFO_DATAFILE_TMP, "w", true)) == NULL)
+	/* use the same permissions as the data directory for the new file */
+	oumask = umask(pg_mode_mask);
+	fh = fopen(LOG_METAINFO_DATAFILE_TMP, "w");
+	umask(oumask);
+
+	if (fh)
+	{
+		setvbuf(fh, NULL, PG_IOLBF, 0);
+
+#ifdef WIN32
+		/* use CRLF line endings on Windows */
+		_setmode(_fileno(fh), _O_TEXT);
+#endif
+	}
+	else
 	{
 		ereport(LOG,
 				(errcode_for_file_access(),


[parent: 280a408b48d5]