Import Tcl-core 8.6.6 (as of svn r86089)

compat/mkstemp.c

@@ -0,0 +1,78 @@
+/*
+ * mkstemp.c --
+ *
+ *	Source code for the "mkstemp" library routine.
+ *
+ * Copyright (c) 2009 Donal K. Fellows
+ *
+ * See the file "license.terms" for information on usage and redistribution of
+ * this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * mkstemp --
+ *
+ *	Create an open temporary file from a template.
+ *
+ * Results:
+ *	A file descriptor, or -1 (with errno set) in the case of an error.
+ *
+ * Side effects:
+ *	The template is updated to contain the real filename.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+mkstemp(
+    char *template)		/* Template for filename. */
+{
+    static const char alphanumerics[] =
+	"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+    register char *a, *b;
+    int fd, count, alphanumericsLen = strlen(alphanumerics); /* == 62 */
+
+    a = template + strlen(template);
+    while (a > template && *(a-1) == 'X') {
+	a--;
+    }
+
+    if (a == template) {
+	errno = ENOENT;
+	return -1;
+    }
+
+    /*
+     * We'll only try up to 10 times; after that, we're suffering from enemy
+     * action and should let the caller know.
+     */
+
+    count = 10;
+    do {
+	/*
+	 * Replace the X's in the original template with random alphanumeric
+	 * digits.
+	 */
+
+	for (b=a ; *b ; b++) {
+	    float r = rand() / ((float) RAND_MAX);
+
+	    *b = alphanumerics[(int)(r * alphanumericsLen)];
+	}
+
+	/*
+	 * Template is now realized; try to open (with correct options).
+	 */
+
+	fd = open(template, O_RDWR|O_CREAT|O_EXCL, 0600);
+    } while (fd == -1 && errno == EEXIST && --count > 0);
+
+    return fd;
+}