From d82801ecc8503b5f1d40e1db3096d354e5e49aaa Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@maluuba.com>
Date: Mon, 28 Sep 2015 12:50:20 -0400
Subject: [PATCH] Update the locale thread-safely.

setlocale() affects the entire process, potentially changing the locale
while another thread is executing.  In POSIX.1-2008, a thread-safe
uselocale() function was added that affects only the current thread.
Use this function instead when it's available.
---
 linear.cpp | 72 ++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 54 insertions(+), 18 deletions(-)

diff --git a/linear.cpp b/linear.cpp
index f9b9bdc..ecae138 100644
--- a/linear.cpp
+++ b/linear.cpp
@@ -4,8 +4,14 @@
 #include <string.h>
 #include <stdarg.h>
 #include <locale.h>
+
+#if __unix__
+#	include <unistd.h> // For _POSIX_VERSION
+#endif
+
 #include "linear.h"
 #include "tron.h"
+
 typedef signed char schar;
 template <class T> static inline void swap(T& x, T& y) { T t=x; x=y; y=t; }
 #ifndef min
@@ -2713,6 +2719,49 @@ static const char *solver_type_table[]=
 	"L2R_L2LOSS_SVR", "L2R_L2LOSS_SVR_DUAL", "L2R_L1LOSS_SVR_DUAL", NULL
 };
 
+#if _POSIX_VERSION >= 200809L
+
+// If possible, use the thread-safe uselocale() function
+typedef locale_t locale_handle;
+
+static locale_handle set_c_locale()
+{
+	locale_handle c_locale = newlocale(LC_ALL_MASK, "C", 0);
+	locale_handle old_locale = uselocale(c_locale);
+	return old_locale;
+}
+
+static void restore_locale(locale_handle locale)
+{
+	locale_handle c_locale = uselocale(locale);
+	if (c_locale && c_locale != LC_GLOBAL_LOCALE) {
+		freelocale(c_locale);
+	}
+}
+
+#else
+
+// But fall back to setlocale() if uselocale() is not available
+typedef char *locale_handle;
+
+static locale_handle set_c_locale()
+{
+	locale_handle old_locale = setlocale(LC_ALL, NULL);
+	if (old_locale) {
+		old_locale = strdup(old_locale);
+	}
+	setlocale(LC_ALL, "C");
+	return old_locale;
+}
+
+static void restore_locale(locale_handle locale)
+{
+	setlocale(LC_ALL, locale);
+	free(locale);
+}
+
+#endif
+
 int save_model(const char *model_file_name, const struct model *model_)
 {
 	int i;
@@ -2728,12 +2777,7 @@ int save_model(const char *model_file_name, const struct model *model_)
 	FILE *fp = fopen(model_file_name,"w");
 	if(fp==NULL) return -1;
 
-	char *old_locale = setlocale(LC_ALL, NULL);
-	if (old_locale)
-	{
-		old_locale = strdup(old_locale);
-	}
-	setlocale(LC_ALL, "C");
+	locale_handle old_locale = set_c_locale();
 
 	int nr_w;
 	if(model_->nr_class==2 && model_->param.solver_type != MCSVM_CS)
@@ -2765,8 +2809,7 @@ int save_model(const char *model_file_name, const struct model *model_)
 		fprintf(fp, "\n");
 	}
 
-	setlocale(LC_ALL, old_locale);
-	free(old_locale);
+	restore_locale(old_locale);
 
 	if (ferror(fp) != 0 || fclose(fp) != 0) return -1;
 	else return 0;
@@ -2790,10 +2833,9 @@ int save_model(const char *model_file_name, const struct model *model_)
 // EXIT_LOAD_MODEL should NOT end with a semicolon.
 #define EXIT_LOAD_MODEL()\
 {\
-	setlocale(LC_ALL, old_locale);\
+	restore_locale(old_locale);\
 	free(model_->label);\
 	free(model_);\
-	free(old_locale);\
 	return NULL;\
 }
 struct model *load_model(const char *model_file_name)
@@ -2811,12 +2853,7 @@ struct model *load_model(const char *model_file_name)
 
 	model_->label = NULL;
 
-	char *old_locale = setlocale(LC_ALL, NULL);
-	if (old_locale)
-	{
-		old_locale = strdup(old_locale);
-	}
-	setlocale(LC_ALL, "C");
+	locale_handle old_locale = set_c_locale();
 
 	char cmd[81];
 	while(1)
@@ -2898,8 +2935,7 @@ struct model *load_model(const char *model_file_name)
 		}
 	}
 
-	setlocale(LC_ALL, old_locale);
-	free(old_locale);
+	restore_locale(old_locale);
 
 	if (ferror(fp) != 0 || fclose(fp) != 0) return NULL;