From 5993c3e83c6f83b36045c75a03ffb1da3d1d283c Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Sat, 29 Jul 2017 20:19:54 -0400
Subject: Detect input file = output file (fixes #29)

---
 libqpdf/QUtil.cc | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

(limited to 'libqpdf')

diff --git a/libqpdf/QUtil.cc b/libqpdf/QUtil.cc
index 86de07f2..eed8d276 100644
--- a/libqpdf/QUtil.cc
+++ b/libqpdf/QUtil.cc
@@ -24,6 +24,7 @@
 #include <io.h>
 #else
 #include <unistd.h>
+#include <sys/stat.h>
 #endif
 
 std::string
@@ -188,6 +189,55 @@ QUtil::tell(FILE* stream)
 #endif
 }
 
+bool
+QUtil::same_file(char const* name1, char const* name2)
+{
+    if ((name1 == 0) || (strlen(name1) == 0) ||
+        (name2 == 0) || (strlen(name2) == 0))
+    {
+        return false;
+    }
+#ifdef _WIN32
+    HANDLE fh1 = CreateFile(name1, GENERIC_READ, FILE_SHARE_READ,
+                            NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+    HANDLE fh2 = CreateFile(name2, GENERIC_READ, FILE_SHARE_READ,
+                            NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+    BY_HANDLE_FILE_INFORMATION fi1;
+    BY_HANDLE_FILE_INFORMATION fi2;
+    bool same = false;
+    if ((fh1 != INVALID_HANDLE_VALUE) &&
+        (fh2 != INVALID_HANDLE_VALUE) &&
+        GetFileInformationByHandle(fh1, &fi1) &&
+        GetFileInformationByHandle(fh2, &fi2) &&
+        (fi1.dwVolumeSerialNumber == fi2.dwVolumeSerialNumber) &&
+        (fi1.nFileIndexLow == fi2.nFileIndexLow) &&
+        (fi1.nFileIndexHigh == fi2.nFileIndexHigh))
+    {
+        same = true;
+    }
+    if (fh1 != INVALID_HANDLE_VALUE)
+    {
+        CloseHandle(fh1);
+    }
+    if (fh2 != INVALID_HANDLE_VALUE)
+    {
+        CloseHandle(fh2);
+    }
+    return same;
+#else
+    struct stat st1;
+    struct stat st2;
+    if ((stat(name1, &st1) == 0) &&
+        (stat(name2, &st2) == 0) &&
+        (st1.st_ino == st2.st_ino) &&
+        (st1.st_dev == st2.st_dev))
+    {
+        return true;
+    }
+#endif
+    return false;
+}
+
 char*
 QUtil::copy_string(std::string const& str)
 {
-- 
cgit v1.2.3-70-g09d2