commit 1d30c2fe19fdbdfd6e5f52102247cf01b87e586e
author Christopher Ferris <cferris@google.com> Tue Sep 16 14:53:39 2014 -0700
committer Christopher Ferris <cferris@google.com> Wed Sep 17 17:10:41 2014 -0700
tree 3f46ac3107116bb56b8f696faf909543afe73159
parent 52ae67d659e92bdd32c7c2a6b4d09dfe94e987fe

Use the correct fuse_init_out structure size.

Kernel 2.6.16 is the first stable kernel with struct fuse_init_out
defined (fuse version 7.6). The structure is the same from 7.6 through
7.22. Beginning with 7.23, the structure increased in size and added
new parameters.

If the kernel only works on minor revs older than or equal to 22,
then use the older structure size since this code only uses the 7.22
version of the structure.

Change-Id: I00d7530e01e6b4718dcd04ad2484959d12ef4a65

fuse_sideload.c

diff --git a/fuse_sideload.c b/fuse_sideload.c
index ab91def..4e11e01 100644
--- a/fuse_sideload.c
+++ b/fuse_sideload.c
@@ -53,6 +53,7 @@
 #include <string.h>
 #include <sys/inotify.h>
 #include <sys/mount.h>
+#include <sys/param.h>
 #include <sys/resource.h>
 #include <sys/stat.h>
 #include <sys/statfs.h>
@@ -117,15 +118,40 @@
 static int handle_init(void* data, struct fuse_data* fd, const struct fuse_in_header* hdr) {
     const struct fuse_init_in* req = data;
     struct fuse_init_out out;
+    size_t fuse_struct_size;
+
+
+    /* Kernel 2.6.16 is the first stable kernel with struct fuse_init_out
+     * defined (fuse version 7.6). The structure is the same from 7.6 through
+     * 7.22. Beginning with 7.23, the structure increased in size and added
+     * new parameters.
+     */
+    if (req->major != FUSE_KERNEL_VERSION || req->minor < 6) {
+        printf("Fuse kernel version mismatch: Kernel version %d.%d, Expected at least %d.6",
+               req->major, req->minor, FUSE_KERNEL_VERSION);
+        return -1;
+    }
+
+    out.minor = MIN(req->minor, FUSE_KERNEL_MINOR_VERSION);
+    fuse_struct_size = sizeof(out);
+#if defined(FUSE_COMPAT_22_INIT_OUT_SIZE)
+    /* FUSE_KERNEL_VERSION >= 23. */
+
+    /* If the kernel only works on minor revs older than or equal to 22,
+     * then use the older structure size since this code only uses the 7.22
+     * version of the structure. */
+    if (req->minor <= 22) {
+        fuse_struct_size = FUSE_COMPAT_22_INIT_OUT_SIZE;
+    }
+#endif
 
     out.major = FUSE_KERNEL_VERSION;
-    out.minor = FUSE_KERNEL_MINOR_VERSION;
     out.max_readahead = req->max_readahead;
     out.flags = 0;
     out.max_background = 32;
     out.congestion_threshold = 32;
     out.max_write = 4096;
-    fuse_reply(fd, hdr->unique, &out, sizeof(out));
+    fuse_reply(fd, hdr->unique, &out, fuse_struct_size);
 
     return NO_STATUS;
 }