1 files changed, 97 insertions, 0 deletions
diff --git a/libGeoIP/pread.c b/libGeoIP/pread.c
new file mode 100644
index 0000000..ae5f462
--- /dev/null
+++ b/libGeoIP/pread.c
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2013  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <io.h>
+#include <stdio.h>
+#include <windows.h>
+
+#include "pread.h"
+
+static CRITICAL_SECTION preadsc;
+
+/* http://stackoverflow.com/a/2390626/1392778 */
+
+#ifdef _MSC_VER
+#pragma section(".CRT$XCU", read)
+#define INITIALIZER2_(f, p)                                                    \
+    static void __cdecl f(void);                                               \
+    __declspec(allocate(".CRT$XCU")) void(__cdecl * f##_)(void) = f;           \
+    __pragma(comment(linker, "/include:" p #f "_")) static void __cdecl f(void)
+#ifdef _WIN64
+#define INITIALIZER(f) INITIALIZER2_(f, "")
+#else
+#define INITIALIZER(f) INITIALIZER2_(f, "_")
+#endif
+#elif defined(__GNUC__)
+#define INITIALIZER(f)                                                         \
+    static void f(void) __attribute__((constructor));                          \
+    static void f(void)
+#endif
+
+#ifdef _WIN64
+int pread(int fd, void *buf, unsigned int nbyte, __int64 offset) {
+    int cc = -1;
+    __int64 prev = (__int64)-1L;
+
+    EnterCriticalSection(&preadsc);
+    prev = _lseeki64(fd, 0L, SEEK_CUR);
+    if (prev == (__int64)-1L) {
+        goto done;
+    }
+    if (_lseeki64(fd, offset, SEEK_SET) != offset) {
+        goto done;
+    }
+    cc = _read(fd, buf, nbyte);
+
+done:
+    if (prev != (__int64)-1L) {
+        (void)_lseeki64(fd, prev, SEEK_SET);
+    }
+    LeaveCriticalSection(&preadsc);
+
+    return cc;
+}
+#else
+int pread(int fd, void *buf, unsigned int nbyte, long offset) {
+    int cc = -1;
+    long prev = -1L;
+
+    EnterCriticalSection(&preadsc);
+    prev = _lseek(fd, 0L, SEEK_CUR);
+    if (prev == -1L) {
+        goto done;
+    }
+    if (_lseek(fd, offset, SEEK_SET) != offset) {
+        goto done;
+    }
+    cc = _read(fd, buf, nbyte);
+
+done:
+    if (prev != -1L) {
+        (void)_lseek(fd, prev, SEEK_SET);
+    }
+    LeaveCriticalSection(&preadsc);
+
+    return cc;
+}
+#endif
+
+static void deinitialize(void) { DeleteCriticalSection(&preadsc); }
+
+INITIALIZER(initialize) {
+    InitializeCriticalSection(&preadsc);
+    atexit(deinitialize);
+}