[review v6] Use ctime_r and localtime_r for threadsafety

["Christian Biesinger (Code Review)" <gerrit@gnutoolchain-gerrit.osci.io>]

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/475
......................................................................

Use ctime_r and localtime_r for threadsafety

To make these calls threadsafe. localtime_r is provided by gnulib if
necessary, and for ctime_r we can just use it because it is in a linux-
specific file.

gdb/ChangeLog:

2019-11-15  Christian Biesinger  <cbiesinger@google.com>

	* maint.c (scoped_command_stats::print_time): Use localtime_r
	instead of localtime (provided through gnulib if necessary).
	* nat/linux-osdata.c (time_from_time_t): Use ctime_r instead
	of ctime.

Change-Id: I329bbdc39d5b576f51859ba00f1617e024c30cbd
---
M gdb/ChangeLog
M gdb/maint.c
M gdb/nat/linux-osdata.c
3 files changed, 15 insertions(+), 3 deletions(-)



diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index f31552b..f727aa4 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,12 @@
 2019-11-15  Christian Biesinger  <cbiesinger@google.com>
 
+	* maint.c (scoped_command_stats::print_time): Use localtime_r
+	instead of localtime (provided through gnulib if necessary).
+	* nat/linux-osdata.c (time_from_time_t): Use ctime_r instead
+	of ctime.
+
+2019-11-15  Christian Biesinger  <cbiesinger@google.com>
+
 	* gdbsupport/common-defs.h: Include time.h before pathmax.h to
 	avoid compile errors.
 
diff --git a/gdb/maint.c b/gdb/maint.c
index ec9f4ab..a253584 100644
--- a/gdb/maint.c
+++ b/gdb/maint.c
@@ -1039,10 +1039,11 @@
   auto millis = ticks % 1000;
 
   std::time_t as_time = system_clock::to_time_t (now);
-  struct tm *tm = localtime (&as_time);
+  struct tm tm;
+  localtime_r (&as_time, &tm);
 
   char out[100];
-  strftime (out, sizeof (out), "%F %H:%M:%S", tm);
+  strftime (out, sizeof (out), "%F %H:%M:%S", &tm);
 
   printf_unfiltered ("%s.%03d - %s\n", out, (int) millis, msg);
 }
diff --git a/gdb/nat/linux-osdata.c b/gdb/nat/linux-osdata.c
index ca6acd3..d82c062 100644
--- a/gdb/nat/linux-osdata.c
+++ b/gdb/nat/linux-osdata.c
@@ -916,7 +916,11 @@
     {
       time_t t = (time_t) seconds;
 
-      strncpy (time, ctime (&t), maxlen);
+      /* Per the ctime_r manpage, this buffer needs to be at least 26
+         characters long.  */
+      char buf[30];
+      const char *time_str = ctime_r (&t, buf);
+      strncpy (time, time_str, maxlen);
       time[maxlen - 1] = '\0';
     }
 }

-- 
Gerrit-Project: binutils-gdb
Gerrit-Branch: master
Gerrit-Change-Id: I329bbdc39d5b576f51859ba00f1617e024c30cbd
Gerrit-Change-Number: 475
Gerrit-PatchSet: 6
Gerrit-Owner: Christian Biesinger <cbiesinger@google.com>
Gerrit-Reviewer: Christian Biesinger <cbiesinger@google.com>
Gerrit-Reviewer: Kevin Buettner <kevinb@redhat.com>
Gerrit-MessageType: newpatchset