Add mkdtemp(3).

libc/Makefile

@@ -450,6 +450,7 @@ stdlib/clearenv.o \
 stdlib/_Exit.o \
 stdlib/exit.o \
 stdlib/getenv.o \
+stdlib/mkdtemp.o \
 stdlib/mkostemp.o \
 stdlib/mkostemps.o \
 stdlib/mkstemp.o \

libc/include/stdlib.h

@@ -105,6 +105,7 @@ void* malloc(size_t);
 int mblen(const char*, size_t);
 size_t mbstowcs(wchar_t* __restrict, const char* __restrict, size_t);
 int mbtowc(wchar_t *__restrict, const char* __restrict, size_t);
+char* mkdtemp(char*);
 int mkostemp(char*, int);
 int mkostemps(char*, int, int);
 int mkstemp(char*);
@@ -161,7 +162,6 @@ long jrand48(unsigned short [3]);
 char* l64a(long);
 void lcong48(unsigned short [7]);
 long lrand48(void);
-char* mkdtemp(char*);
 long mrand48(void);
 long nrand48(unsigned short[3]);
 int posix_memalign(void**, size_t, size_t);

libc/stdlib/mkdtemp.cpp

@@ -0,0 +1,63 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2013, 2014, 2015.
+
+    This file is part of the Sortix C Library.
+
+    The Sortix C Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or (at your
+    option) any later version.
+
+    The Sortix C Library is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
+
+    stdlib/mkdtemp.cpp
+    Make a unique temporary directory path and create it.
+
+*******************************************************************************/
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+
+const uint32_t NUM_CHARACTERS = 10 + 26 + 26;
+
+static inline char random_character()
+{
+	uint32_t index = arc4random_uniform(NUM_CHARACTERS);
+	if ( index < 10 )
+		return '0' + index;
+	if ( index < 10 + 26 )
+		return 'a' + index - 10;
+	if ( index < 10 + 26 + 26 )
+		return 'A' + index - (10 + 26);
+	__builtin_unreachable();
+}
+
+extern "C" char* mkdtemp(char* templ)
+{
+	size_t templ_length = strlen(templ);
+	if ( templ_length < 6 )
+		return errno = EINVAL, (char*) NULL;
+	size_t xpos = templ_length - 6;
+	for ( size_t i = 0; i < 6; i++ )
+		if ( templ[xpos + i] != 'X' )
+			return errno = EINVAL, (char*) NULL;
+
+	do
+	{
+		for ( size_t i = 0; i < 6; i++ )
+			templ[xpos + i] = random_character();
+		if ( mkdir(templ, 0700) == 0 )
+			return templ;
+	} while ( errno == EEXIST );
+
+	return NULL;
+}