add mkostemp, mkstemps, and mkostemps functions and reorganize temp internals

based on patch contributed by Anthony G. Basile (blueness)

some issues remain with the filename generation algorithm and other
small bugs, but this patch has been sitting around long enough that I
feel it's best to get it committed and then work out any remaining
issues.

include/stdlib.h

@@ -95,6 +95,7 @@ int posix_memalign (void **, size_t, size_t);
 int setenv (const char *, const char *, int);
 int unsetenv (const char *);
 int mkstemp (char *);
+int mkostemp (char *, int);
 char *mkdtemp (char *);
 int getsubopt (char **, char *const *, char **);
 int rand_r (unsigned *);
@@ -134,6 +135,8 @@ void lcong48 (unsigned short [7]);
 #if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
 #include <alloca.h>
 char *mktemp (char *);
+int mkstemps (char *, int);
+int mkostemps (char *, int, int);
 void *valloc (size_t);
 void *memalign(size_t, size_t);
 #define WCOREDUMP(s) ((s) & 0x80)
@@ -150,6 +153,11 @@ char *gcvt(double, int, char *);
 
 #if defined(_LARGEFILE64_SOURCE) || defined(_GNU_SOURCE)
 #define mkstemp64 mkstemp
+#define mkostemp64 mkostemp
+#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+#define mkstemps64 mkstemps
+#define mkostemps64 mkostemps
+#endif
 #endif
 
 #ifdef __cplusplus

src/temp/__randname.c

+#include <string.h>
+#include <time.h>
+#include <stdint.h>
+
+int __clock_gettime(clockid_t, struct timespec *);
+
+/* This assumes that a check for the
+   template size has alrady been made */
+char *__randname(char *template)
+{
+	int i;
+	struct timespec ts;
+	unsigned long r;
+
+	__clock_gettime(CLOCK_REALTIME, &ts);
+	r = ts.tv_nsec*65537 ^ (uintptr_t)&ts / 16 + (uintptr_t)template;
+	for (i=0; i<6; i++, r>>=5)
+		template[i] = 'A'+(r&15)+(r&16)*2;
+
+	return template;
+}

src/temp/mkostemp.c

+#define _BSD_SOURCE
+#include <stdlib.h>
+#include "libc.h"
+
+int __mkostemps(char *, int, int);
+
+int mkostemp(char *template, int flags)
+{
+	return __mkostemps(template, 0, flags);
+}
+
+LFS64(mkostemp);

src/temp/mkostemps.c

+#define _BSD_SOURCE
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include "libc.h"
+
+char *__randname(char *);
+
+int __mkostemps(char *template, int len, int flags)
+{
+	if (len < 0) return EINVAL;
+
+	size_t l = strlen(template)-len;
+	if (l < 6 || strncmp(template+l-6, "XXXXXX", 6)) {
+		errno = EINVAL;
+		*template = 0;
+		return -1;
+	}
+
+	int fd, retries = 100;
+	while (retries--) {
+		__randname(template+l-6);
+		if ((fd = open(template, flags | O_RDWR | O_CREAT | O_EXCL, 0600))>=0)
+			return fd;
+		if (errno != EEXIST) return -1;
+	}
+	return -1;
+}
+
+weak_alias(__mkostemps, mkostemps);
+weak_alias(__mkostemps, mkostemps64);

src/temp/mkstemp.c

-#include <string.h>
-#include <stdio.h>
 #include <stdlib.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <limits.h>
-#include <errno.h>
 #include "libc.h"
 
-char *__mktemp(char *);
+int __mkostemps(char *, int, int);
 
 int mkstemp(char *template)
 {
-	int fd, retries = 100, t0 = *template;
-	while (retries--) {
-		if (!*__mktemp(template)) return -1;
-		if ((fd = open(template, O_RDWR | O_CREAT | O_EXCL, 0600))>=0)
-			return fd;
-		if (errno != EEXIST) return -1;
-		/* this is safe because mktemp verified
-		 * that we have a valid template string */
-		template[0] = t0;
-		strcpy(template+strlen(template)-6, "XXXXXX");
-	}
-	return -1;
+	return __mkostemps(template, 0, 0);
 }
 
 LFS64(mkstemp);

src/temp/mkstemps.c

+#define _BSD_SOURCE
+#include <stdlib.h>
+#include "libc.h"
+
+int __mkostemps(char *, int, int);
+
+int mkstemps(char *template, int len)
+{
+	return __mkostemps(template, len, 0);
+}
+
+LFS64(mkstemps);

src/temp/mktemp.c

 #include <string.h>
-#include <stdio.h>
-#include <stdlib.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <errno.h>
-#include <time.h>
-#include <stdint.h>
 #include "libc.h"
 
+char *__randname(char *);
+
 char *__mktemp(char *template)
 {
-	struct timespec ts;
-	size_t i, l = strlen(template);
+	size_t l = strlen(template);
 	int retries = 10000;
 	unsigned long r;
 
@@ -21,10 +18,7 @@ char *__mktemp(char *template)
 		return template;
 	}
 	while (retries--) {
-		clock_gettime(CLOCK_REALTIME, &ts);
-		r = ts.tv_nsec + (uintptr_t)&ts / 16 + (uintptr_t)template;
-		for (i=1; i<=6; i++, r>>=4)
-			template[l-i] = 'A'+(r&15);
+		__randname(template+l-6);
 		if (access(template, F_OK) < 0) return template;
 	}
 	*template = 0;