initial import

[vym] / mkdtemp.cpp

diff --git a/mkdtemp.cpp b/mkdtemp.cpp
new file mode 100644 (file)
index 0000000..a6968d4
--- /dev/null
+++ b/mkdtemp.cpp
@@ -0,0 +1,67 @@
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+#include <io.h>
+#include <sys/time.h>
+
+extern "C" {
+pid_t getpid (void);
+}
+
+char *
+mkdtemp(char *tmpl)
+{
+    // Implementation based on GLIBC implementation.
+
+    static const char letters[] =
+        "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+
+    static uint64_t value;
+
+    const unsigned int ATTEMPTS_MIN = (62 * 62 * 62);
+
+    int save_errno = errno;
+
+    size_t len = strlen(tmpl);
+    if (len < 6 || strcmp(&tmpl[len - 6], "XXXXXX"))
+    {
+        errno = EINVAL;
+        return NULL;
+    }
+
+    char *XXXXXX = &tmpl[len - 6];
+
+    uint64_t random_time_bits = time(NULL);
+
+    value += (random_time_bits ^ getpid());
+
+    unsigned int count;
+    for (count = 0; count < ATTEMPTS_MIN; value += 7777, ++count)
+    {
+        uint64_t v = value;
+
+        XXXXXX[0] = letters[v % 62];
+        v /= 62;
+        XXXXXX[1] = letters[v % 62];
+        v /= 62;
+        XXXXXX[2] = letters[v % 62];
+        v /= 62;
+        XXXXXX[3] = letters[v % 62];
+        v /= 62;
+        XXXXXX[4] = letters[v % 62];
+        v /= 62;
+        XXXXXX[5] = letters[v % 62];
+
+               if (mkdir(tmpl) == 0)
+        {
+            errno = save_errno;
+                       return tmpl;
+        }
+
+               if (errno != EEXIST)
+                       return NULL;
+    }
+
+    errno = EEXIST;
+    return NULL;
+}