[syslinux] [PATCH 3/5] installers: MSVC compatibility fixes

[Pete Batard]

More MSVC compatibility fixes, for packed structures.
NB: In case you are aware of the issues that may come with MS vs GCC 
packing, so far, I have not seen evidence of detrimental impact from 
using ms_struct packing in MSVC (vs gcc_struct, which is explicitly 
specified for MinGW), with regards to the sections of code I am using in 
Rufus.
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From 13b39c1f113a8bc5621249db21a382a689aa174e Mon Sep 17 00:00:00 2001
From: Pete Batard <pete at akeo.ie>
Date: Tue, 23 Feb 2016 19:57:28 +0000
Subject: [PATCH 3/5] installers: MSVC compatibility fixes

---
 libinstaller/syslxint.h | 13 ++++++++++++-
 libinstaller/syslxmod.c |  3 ++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/libinstaller/syslxint.h b/libinstaller/syslxint.h
index 7eee789..9ff63f2 100644
--- a/libinstaller/syslxint.h
+++ b/libinstaller/syslxint.h
@@ -17,7 +17,7 @@
 
 #include "syslinux.h"
 
-#if defined(__386__) || defined(__i386__) || defined(__x86_64__)
+#if defined(__386__) || defined(__i386__) || defined(__x86_64__) || defined(_M_IX86) || defined(_M_X64)
 # define X86_MEM 1		/* Littleendian and unaligned safe */
 #else
 # define X86_MEM 0
@@ -26,10 +26,15 @@
 #ifdef __GNUC__
 # ifdef __MINGW32__
    /* gcc 4.7 miscompiles packed structures in MS-bitfield mode */
+#  define PACKME
 #  define PACKED __attribute__((packed,gcc_struct))
 # else
+#  define PACKME
 #  define PACKED __attribute__((packed))
 # endif
+#elif defined(_MSC_VER)
+# define PACKME __pragma(pack(push, 1))
+# define PACKED __pragma(pack(pop))
 #else
 # error "Need to define PACKED for this compiler"
 #endif
@@ -214,12 +219,14 @@ struct ext_patch_area {
 };
 
 /* Sector extent */
+PACKME
 struct syslinux_extent {
     uint64_t lba;
     uint16_t len;
 } PACKED;
 
 /* FAT bootsector format, also used by other disk-based derivatives */
+PACKME
 struct fat_boot_sector {
     uint8_t bsJump[3];
     char bsOemName[8];
@@ -236,7 +243,9 @@ struct fat_boot_sector {
     uint32_t bsHiddenSecs;
     uint32_t bsHugeSectors;
 
+    PACKME
     union {
+	PACKME
 	struct {
 	    uint8_t DriveNumber;
 	    uint8_t Reserved1;
@@ -246,6 +255,7 @@ struct fat_boot_sector {
 	    char FileSysType[8];
 	    uint8_t Code[442];
 	} PACKED bs16;
+	PACKME
 	struct {
 	    uint32_t FATSz32;
 	    uint16_t ExtFlags;
@@ -270,6 +280,7 @@ struct fat_boot_sector {
 } PACKED;
 
 /* NTFS bootsector format */
+PACKME
 struct ntfs_boot_sector {
     uint8_t bsJump[3];
     char bsOemName[8];
diff --git a/libinstaller/syslxmod.c b/libinstaller/syslxmod.c
index 0ec4164..7bf4d91 100644
--- a/libinstaller/syslxmod.c
+++ b/libinstaller/syslxmod.c
@@ -41,7 +41,8 @@ static void generate_extents(struct syslinux_extent _slimg *ex, int nptrs,
     unsigned int len;
 
     base = addr;
-    len = lba = 0;
+    len = 0;
+    lba = 0;
 
     memset_sl(ex, 0, nptrs * sizeof *ex);
 
-- 
1.9.5.msysgit.1