Don't fsync() read-only filehandles (thanks, Andreas!).

This sounds harmless, but it actually forces a write of the inode's atime, which means a lot of painful and unnecessary disk i/o on some filesystems. Should be a good speedup on games that read a lot of small files on Unix.
icculus · Aug 22, 2013 · 09baf99 · 09baf99
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diff --git a/docs/CREDITS.txt b/docs/CREDITS.txt
@@ -136,6 +136,9 @@ SLB archiver:
 Bug fixes:
     Dmitry Marakasov
 
+Bug fixes:
+    Andreas Karlsson
+
 Other stuff:
     Your name here! Patches go to icculus@icculus.org ...
 

diff --git a/src/platform_posix.c b/src/platform_posix.c
@@ -279,7 +279,8 @@ PHYSFS_sint64 __PHYSFS_platformFileLength(void *opaque)
 int __PHYSFS_platformFlush(void *opaque)
 {
     const int fd = *((int *) opaque);
-    BAIL_IF_MACRO(fsync(fd) == -1, errcodeFromErrno(), 0);
+    if ((fcntl(fd, F_GETFL) & O_ACCMODE) != O_RDONLY)
+        BAIL_IF_MACRO(fsync(fd) == -1, errcodeFromErrno(), 0);
     return 1;
 } /* __PHYSFS_platformFlush */