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List:       git
Subject:    [PATCH] builtin/bugreport.c: use thread-safe localtime_r()
From:       Taylor Blau <me () ttaylorr ! com>
Date:       2020-11-30 23:06:44
Message-ID: 27fc158339c91f56210f00dae9015da1d6c781ec.1606777520.git.me () ttaylorr ! com
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To generate its filename, the 'git bugreport' builtin asks the system
for the current time with 'localtime()'. Since this uses a shared
buffer, it is not thread-safe.

Even though 'git bugreport' is not multi-threaded, using localtime() can
trigger some static analysis tools to complain, and a quick

    $ git grep -oh 'localtime\(_.\)\?' -- **/*.c | sort | uniq -c

shows that the only usage of the thread-unsafe 'localtime' is in a piece
of documentation.

So, convert this instance to use the thread-safe version for
consistency, and to appease some analysis tools.
---
Some folks at GitHub sent me the output of a static analysis tool run
against our private fork, and this usage of 'localtime()' showed up.

This is purely academic, since this clearly isn't a thread-unsafe usage
of that function, but it should appease any other static analysis tools
that folks might run.

 builtin/bugreport.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/builtin/bugreport.c b/builtin/bugreport.c
index 3ad4b9b62e..ad3cc9c02f 100644
--- a/builtin/bugreport.c
+++ b/builtin/bugreport.c
@@ -125,6 +125,7 @@ int cmd_bugreport(int argc, const char **argv, const char *prefix)
 	struct strbuf report_path = STRBUF_INIT;
 	int report = -1;
 	time_t now = time(NULL);
+	struct tm tm;
 	char *option_output = NULL;
 	char *option_suffix = "%Y-%m-%d-%H%M";
 	const char *user_relative_path = NULL;
@@ -147,7 +148,7 @@ int cmd_bugreport(int argc, const char **argv, const char *prefix)
 	strbuf_complete(&report_path, '/');

 	strbuf_addstr(&report_path, "git-bugreport-");
-	strbuf_addftime(&report_path, option_suffix, localtime(&now), 0, 0);
+	strbuf_addftime(&report_path, option_suffix, localtime_r(&now, &tm), 0, 0);
 	strbuf_addstr(&report_path, ".txt");

 	switch (safe_create_leading_directories(report_path.buf)) {
--
2.29.2.533.g07db1f5344
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