From 1d634f9b44d2e4b7d7f14d1787041de7843f3bc6 Mon Sep 17 00:00:00 2001
From: Jonathan Li <jonathan.li@hotmail.co.uk>
Date: Wed, 7 Dec 2016 00:54:11 +0000
Subject: [PATCH] cdvdgigaherz:linux: Use pread instead of lseek + read

It'll make it unnecessary to use a lock when reading disc sectors.
---
 plugins/cdvdGigaherz/src/CDVD.h                 |  2 +-
 plugins/cdvdGigaherz/src/Unix/LinuxIOCtlSrc.cpp | 10 +---------
 2 files changed, 2 insertions(+), 10 deletions(-)

diff --git a/plugins/cdvdGigaherz/src/CDVD.h b/plugins/cdvdGigaherz/src/CDVD.h
index ddc3547460..41856aeef6 100644
--- a/plugins/cdvdGigaherz/src/CDVD.h
+++ b/plugins/cdvdGigaherz/src/CDVD.h
@@ -63,6 +63,7 @@ class IOCtlSrc
 #if defined(_WIN32)
     HANDLE m_device = INVALID_HANDLE_VALUE;
     std::wstring m_filename;
+    mutable std::mutex m_lock;
 #else
     int m_device = -1;
     std::string m_filename;
@@ -72,7 +73,6 @@ class IOCtlSrc
     u32 m_sectors = 0;
     u32 m_layer_break = 0;
     std::vector<toc_entry> m_toc;
-    mutable std::mutex m_lock;
 
     bool ReadDVDInfo();
     bool ReadCDInfo();
diff --git a/plugins/cdvdGigaherz/src/Unix/LinuxIOCtlSrc.cpp b/plugins/cdvdGigaherz/src/Unix/LinuxIOCtlSrc.cpp
index 59b5694536..500043bec2 100644
--- a/plugins/cdvdGigaherz/src/Unix/LinuxIOCtlSrc.cpp
+++ b/plugins/cdvdGigaherz/src/Unix/LinuxIOCtlSrc.cpp
@@ -86,16 +86,8 @@ const std::vector<toc_entry> &IOCtlSrc::ReadTOC() const
 
 bool IOCtlSrc::ReadSectors2048(u32 sector, u32 count, u8 *buffer) const
 {
-    std::lock_guard<std::mutex> guard(m_lock);
-
-    if (lseek(m_device, sector * 2048ULL, SEEK_SET) == -1) {
-        fprintf(stderr, " * CDVD lseek sectors %u failed: %s\n",
-                sector, strerror(errno));
-        return false;
-    }
-
     const ssize_t bytes_to_read = 2048 * count;
-    ssize_t bytes_read = read(m_device, buffer, bytes_to_read);
+    ssize_t bytes_read = pread(m_device, buffer, bytes_to_read, sector * 2048ULL);
     if (bytes_read == bytes_to_read)
         return true;