patch-2.3.2 linux/fs/hpfs/mmap.c

• Lines: 129
• Date: Thu May 13 23:48:20 1999
• Orig file: v2.3.1/linux/fs/hpfs/mmap.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.1/linux/fs/hpfs/mmap.c linux/fs/hpfs/mmap.c
@@ -0,0 +1,128 @@
+/*
+ *  linux/fs/hpfs/mmap.c
+ *
+ *  taken from fat filesystem
+ *
+ *  Written by Jacques Gelinas (jacques@solucorp.qc.ca)
+ *  Inspired by fs/nfs/mmap.c (Jon Tombs 15 Aug 1993)
+ *
+ *  Modified for HPFS by Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz)
+ *
+ *  mmap handling for hpfs filesystem
+ *	(generic_file_mmap may be used only on filesystems that keep zeros
+ *	 in last file sector beyond end)
+ */
+
+/*
+ * generic_file_mmap doesn't erase the space beyond file end in last sector. :-(
+ * Hpfs doesn't keep zeros in last sector. This causes problems with kernel
+ * mkdep.c and probably other programs. Additionally this could be a security
+ * hole - some interesting data, like pieces of /etc/shadow could be found
+ * beyond file end.
+ *
+ * So, I can't use generic mmap. mmap from fat filesystem looks good, so I used
+ * it.
+ *
+ * BTW. fat uses generic mmap on normal disks. Doesn't it also have above bugs?
+ * I don't think Msdos erases space in last sector.
+ *
+ * If you fix generic_file_mmap, you can remove this file and use it.
+ */
+
+#include "hpfs_fn.h"
+
+/*
+ * Fill in the supplied page for mmap
+ */
+
+static unsigned long hpfs_file_mmap_nopage(
+	struct vm_area_struct * area,
+	unsigned long address,
+	int error_code)
+{
+	/*struct inode * inode = area->vm_inode;*/
+	struct inode * inode = area->vm_file->f_dentry->d_inode;
+	unsigned long page;
+	unsigned int clear;
+	loff_t pos;
+	long gap;	/* distance from eof to pos */
+
+	page = __get_free_page(GFP_KERNEL);
+	if (!page)
+		return page;
+	address &= PAGE_MASK;
+	pos = address - area->vm_start + area->vm_offset;
+
+	clear = 0;
+	gap = inode->i_size - pos;
+	if (gap <= 0){
+		/* mmaping beyond end of file */
+		clear = PAGE_SIZE;
+	}else{
+		int cur_read;
+		int need_read;
+		/*struct file *filp = area->vm_file;*/
+		struct file filp;
+		if (gap < PAGE_SIZE){
+			clear = PAGE_SIZE - gap;
+		}
+		filp.f_reada = 0;
+		filp.f_pos = pos;
+		filp.f_dentry=area->vm_file->f_dentry;
+		need_read = PAGE_SIZE - clear;
+		{
+			mm_segment_t cur_fs = get_fs();
+			set_fs (KERNEL_DS);
+			cur_read = generic_file_read (&filp,(char*)page
+				,need_read,&pos);
+			set_fs (cur_fs);
+		}
+		if (cur_read != need_read){
+			hpfs_error(inode->i_sb, "Error while reading an mmap file %08x", inode->i_ino);
+		}
+	}
+	if (clear > 0){
+		memset ((char*)page+PAGE_SIZE-clear,0,clear);
+	}
+	return page;
+}
+
+struct vm_operations_struct hpfs_file_mmap = {
+	NULL,			/* open */
+	NULL,			/* close */
+	NULL,			/* unmap */
+	NULL,			/* protect */
+	NULL,			/* sync */
+	NULL,			/* advise */
+	hpfs_file_mmap_nopage,	/* nopage */
+	NULL,			/* wppage */
+	NULL,			/* swapout */
+	NULL,			/* swapin */
+};
+
+/*
+ * This is used for a general mmap of an msdos file
+ * Returns 0 if ok, or a negative error code if not.
+ */
+int hpfs_mmap(struct file * file, struct vm_area_struct * vma)
+{
+	struct inode *inode = file->f_dentry->d_inode;
+	/*printk("start mmap\n");*/
+	if (vma->vm_flags & VM_SHARED)	/* only PAGE_COW or read-only supported now */
+		return -EINVAL;
+	if (vma->vm_offset & (inode->i_sb->s_blocksize - 1))
+		return -EINVAL;
+	if (!inode->i_sb || !S_ISREG(inode->i_mode))
+		return -EACCES;
+	/*if (!IS_RDONLY(inode)) {
+		inode->i_atime = CURRENT_TIME;
+		mark_inode_dirty(inode);
+	}*/
+
+	vma->vm_file = file;
+	/*inode->i_count++;*/
+	file->f_count++;
+	vma->vm_ops = &hpfs_file_mmap;
+	/*printk("end mmap\n");*/
+	return 0;
+}