X-Git-Url: https://wimlib.net/git/?p=wimlib;a=blobdiff_plain;f=src%2Fsymlink.c;h=211073c4d7669eb1cbca4749d22f540a574b5e7f;hp=e243a42a01acc73a34896baf3694332ee34250b3;hb=c7af42d3d894338bbd1cb7f4b77948f746485482;hpb=f46894fd897b721ac3128743147bdbad70d19414

diff --git a/src/symlink.c b/src/symlink.c
index e243a42a..211073c4 100644
--- a/src/symlink.c
+++ b/src/symlink.c
@@ -1,18 +1,48 @@
+/*
+ * symlink.c
+ *
+ * Code to read and set symbolic links in WIM files.
+ */
+
+/*
+ * Copyright (C) 2012 Eric Biggers
+ *
+ * This file is part of wimlib, a library for working with WIM files.
+ *
+ * wimlib is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 3 of the License, or (at your option)
+ * any later version.
+ *
+ * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with wimlib; if not, see http://www.gnu.org/licenses/.
+ */
+
 #include "dentry.h"
-#include "io.h"
+#include "buffer_io.h"
 #include "lookup_table.h"
+#include "sha1.h"
+#include <errno.h>
 
 /*
  * Find the symlink target of a symbolic link or junction point in the WIM.
  *
- * See http://msdn.microsoft.com/en-us/library/cc232006(v=prot.10).aspx
- * Except the first 8 bytes aren't included in the resource (presumably because
- * we already know the reparse tag from the dentry, and we already know the
- * reparse tag len from the lookup table entry resource length).
+ * See http://msdn.microsoft.com/en-us/library/cc232006(v=prot.10).aspx for a
+ * description of the format of the so-called "reparse point data buffers".
+ *
+ * But, in the WIM format, the first 8 bytes of the reparse point data buffer
+ * are omitted, presumably because we already know the reparse tag from the
+ * dentry, and we already know the reparse tag length from the lookup table
+ * entry resource length.
  */
 static ssize_t get_symlink_name(const u8 *resource, size_t resource_len,
 			        char *buf, size_t buf_len,
-			        bool is_junction_point)
+			        u32 reparse_tag)
 {
 	const u8 *p = resource;
 	u16 substitute_name_offset;
@@ -25,6 +55,7 @@ static ssize_t get_symlink_name(const u8 *resource, size_t resource_len,
 	unsigned header_size;
 	char *translated_target;
 	bool is_absolute;
+	u32 flags;
 
 	if (resource_len < 12)
 		return -EIO;
@@ -32,19 +63,30 @@ static ssize_t get_symlink_name(const u8 *resource, size_t resource_len,
 	p = get_u16(p, &substitute_name_len);
 	p = get_u16(p, &print_name_offset);
 	p = get_u16(p, &print_name_len);
-	if (is_junction_point) {
+	get_u32(p, &flags);
+
+	wimlib_assert(reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK ||
+		      reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT);
+
+	if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT) {
 		header_size = 8;
 	} else {
-		u32 flags;
-		p = get_u32(p, &flags);
 		is_absolute = (flags & 1) ? false : true;
 		header_size = 12;
+		p += 4;
 	}
 	if (header_size + substitute_name_offset + substitute_name_len > resource_len)
 		return -EIO;
-	link_target = utf16_to_utf8(p + substitute_name_offset,
-				    substitute_name_len,
-				    &link_target_len);
+
+	ret = utf16_to_utf8((const char *)p + substitute_name_offset,
+			    substitute_name_len,
+			    &link_target, &link_target_len);
+	if (ret == WIMLIB_ERR_INVALID_UTF16_STRING)
+		return -EILSEQ;
+	else if (ret == WIMLIB_ERR_NOMEM)
+		return -ENOMEM;
+
+	wimlib_assert(ret == 0);
 
 	if (!link_target)
 		return -EIO;
@@ -55,7 +97,7 @@ static ssize_t get_symlink_name(const u8 *resource, size_t resource_len,
 	}
 
 	translated_target = link_target;
-	if (is_junction_point || is_absolute) {
+	if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT || is_absolute) {
 		if (link_target_len < 7
 		      || memcmp(translated_target, "\\??\\", 4) != 0
 		      || translated_target[4] == '\0'
@@ -66,10 +108,18 @@ static ssize_t get_symlink_name(const u8 *resource, size_t resource_len,
 		}
 		translated_target += 4;
 		link_target_len -= 4;
+		/* There's a drive letter, so just leave the backslashes since
+		 * it won't go anyhwere on UNIX anyway...
+		 *
+		 * XXX
+		 * NTFS-3g tries to re-map these links to actually point to
+		 * something, so maybe we could do something like that here
+		 * XXX*/
+	} else {
+		for (size_t i = 0; i < link_target_len; i++)
+			if (translated_target[i] == '\\')
+				translated_target[i] = '/';
 	}
-	for (size_t i = 0; i < link_target_len; i++)
-		if (translated_target[i] == '\\')
-			translated_target[i] = '/';
 
 	memcpy(buf, translated_target, link_target_len + 1);
 	ret = link_target_len;
@@ -78,85 +128,137 @@ out:
 	return ret;
 }
 
-void *make_symlink_reparse_data_buf(const char *symlink_target, size_t *len_ret)
+static int make_symlink_reparse_data_buf(const char *symlink_target,
+					 size_t *len_ret, void **buf_ret)
 {
 	size_t utf8_len = strlen(symlink_target);
+	char *name_utf16;
 	size_t utf16_len;
-	char *name_utf16 = utf8_to_utf16(symlink_target, utf8_len, &utf16_len);
-	if (!name_utf16)
-		return NULL;
-	/*DEBUG("utf16_len = %zu", utf16_len);*/
+	int ret;
+
+	ret = utf8_to_utf16(symlink_target, utf8_len,
+			    &name_utf16, &utf16_len);
+	if (ret != 0)
+		return ret;
+
 	for (size_t i = 0; i < utf16_len / 2; i++)
-		if (((u16*)name_utf16)[i] == to_le16('/'))
-			((u16*)name_utf16)[i] = to_le16('\\');
+		if (((u16*)name_utf16)[i] == cpu_to_le16('/'))
+			((u16*)name_utf16)[i] = cpu_to_le16('\\');
 	size_t len = 12 + utf16_len * 2;
 	void *buf = MALLOC(len);
-	if (!buf)
-		goto out;
-
-	u8 *p = buf;
-	p = put_u16(p, 0); /* Substitute name offset */
-	p = put_u16(p, utf16_len); /* Substitute name length */
-	p = put_u16(p, utf16_len); /* Print name offset */
-	p = put_u16(p, utf16_len); /* Print name length */
-	p = put_u32(p, (symlink_target[0] == '/') ?  0 : 1);
-	p = put_bytes(p, utf16_len, name_utf16);
-	p = put_bytes(p, utf16_len, name_utf16);
-	/*DEBUG("utf16_len = %zu, len = %zu", utf16_len, len);*/
-	*len_ret = len;
-out:
+	if (buf) {
+		u8 *p = buf;
+		p = put_u16(p, utf16_len); /* Substitute name offset */
+		p = put_u16(p, utf16_len); /* Substitute name length */
+		p = put_u16(p, 0); /* Print name offset */
+		p = put_u16(p, utf16_len); /* Print name length */
+		p = put_u32(p, 1); /* flags: 0 iff *full* target, including drive letter??? */
+		p = put_bytes(p, utf16_len, (const u8*)name_utf16);
+		p = put_bytes(p, utf16_len, (const u8*)name_utf16);
+		*len_ret = len;
+		*buf_ret = buf;
+		ret = 0;
+	} else {
+		ret = WIMLIB_ERR_NOMEM;
+	}
 	FREE(name_utf16);
-	return buf;
+	return ret;
 }
 
-/* Get the symlink target from a dentry that's already checked to be either a
- * "real" symlink or a junction point. */
-ssize_t dentry_readlink(const struct dentry *dentry, char *buf, size_t buf_len,
-			const WIMStruct *w)
+/* Get the symlink target from a WIM inode.
+ *
+ * The inode may be either a "real" symlink (reparse tag
+ * WIM_IO_REPARSE_TAG_SYMLINK), or it may be a junction point (reparse tag
+ * WIM_IO_REPARSE_TAG_MOUNT_POINT).
+ */
+ssize_t inode_readlink(const struct wim_inode *inode, char *buf, size_t buf_len,
+		       const WIMStruct *w, int read_resource_flags)
 {
-	struct ads_entry *ads;
-	struct lookup_table_entry *entry;
-	struct resource_entry *res_entry;
-	bool is_junction_point;
-
-	wimlib_assert(dentry_is_symlink(dentry));
-
-	if (dentry->reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK) {
-		is_junction_point = false;
-		/* 
-		 * This is of course not actually documented, but what I think is going
-		 * on here is that the symlink dentries have 2 alternate data streams;
-		 * one is the default data stream, which is not used and is empty, and
-		 * one is the symlink buffer data stream, which is confusingly also
-		 * unnamed, but isn't empty as it contains the symlink target within the
-		 * resource.
-		 */
-		if (dentry->num_ads != 2)
-			return -EIO;
-		if ((entry = __lookup_resource(w->lookup_table, dentry->ads_entries[0].hash)))
-			goto do_readlink;
-		if ((entry = __lookup_resource(w->lookup_table, dentry->ads_entries[1].hash)))
-			goto do_readlink;
-	} else {
-		wimlib_assert(dentry->reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT);
+	const struct wim_lookup_table_entry *lte;
+	int ret;
 
-		is_junction_point = true;
+	wimlib_assert(inode_is_symlink(inode));
 
-		if ((entry = __lookup_resource(w->lookup_table, dentry->hash)))
-			goto do_readlink;
-	}
-	return -EIO;
-do_readlink:
-	res_entry = &entry->resource_entry;
-	if (res_entry->original_size > 10000)
+	lte = inode_unnamed_lte(inode, w->lookup_table);
+	if (!lte)
 		return -EIO;
-	char res_buf[res_entry->original_size];
-	if (read_full_resource(w->fp, res_entry->size, 
-			       res_entry->original_size,
-			       res_entry->offset,
-			       wim_resource_compression_type(w, res_entry),
-			       res_buf) != 0)
+
+	if (wim_resource_size(lte) > 10000)
 		return -EIO;
-	return get_symlink_name(res_buf, res_entry->original_size, buf,
-				buf_len, is_junction_point);
+
+	u8 res_buf[wim_resource_size(lte)];
+	ret = read_full_wim_resource(lte, res_buf, read_resource_flags);
+	if (ret != 0)
+		return -EIO;
+	return get_symlink_name(res_buf, wim_resource_size(lte), buf,
+				buf_len, inode->i_reparse_tag);
+}
+
+/*
+ * Sets @inode to be a symbolic link pointing to @target.
+ *
+ * A lookup table entry for the symbolic link data buffer is created and
+ * inserted into @lookup_table, unless there is an existing lookup table entry
+ * for the exact same data, in which its reference count is incremented.
+ *
+ * The lookup table entry is returned in @lte_ret.
+ *
+ * On failure @dentry and @lookup_table are not modified.
+ */
+int inode_set_symlink(struct wim_inode *inode, const char *target,
+		      struct wim_lookup_table *lookup_table,
+		      struct wim_lookup_table_entry **lte_ret)
+
+{
+	int ret;
+	size_t symlink_buf_len;
+	struct wim_lookup_table_entry *lte = NULL, *existing_lte;
+	u8 symlink_buf_hash[SHA1_HASH_SIZE];
+	void *symlink_buf;
+
+	ret = make_symlink_reparse_data_buf(target, &symlink_buf_len,
+					    &symlink_buf);
+	if (ret != 0)
+		return ret;
+
+	DEBUG("Made symlink reparse data buf (len = %zu, name len = %zu)",
+			symlink_buf_len, symlink_buf_len);
+
+	sha1_buffer(symlink_buf, symlink_buf_len, symlink_buf_hash);
+
+	existing_lte = __lookup_resource(lookup_table, symlink_buf_hash);
+
+	if (existing_lte) {
+		lte = existing_lte;
+		FREE(symlink_buf);
+		symlink_buf = NULL;
+	} else {
+		DEBUG("Creating new lookup table entry for symlink buf");
+		lte = new_lookup_table_entry();
+		if (!lte) {
+			ret = WIMLIB_ERR_NOMEM;
+			goto out_free_symlink_buf;
+		}
+		lte->resource_location            = RESOURCE_IN_ATTACHED_BUFFER;
+		lte->attached_buffer              = symlink_buf;
+		lte->resource_entry.original_size = symlink_buf_len;
+		lte->resource_entry.size          = symlink_buf_len;
+		copy_hash(lte->hash, symlink_buf_hash);
+	}
+
+	inode->i_lte = lte;
+	inode->i_resolved = 1;
+
+	DEBUG("Loaded symlink buf");
+
+	if (existing_lte)
+		lte->refcnt++;
+	else
+		lookup_table_insert(lookup_table, lte);
+	if (lte_ret)
+		*lte_ret = lte;
+	return 0;
+out_free_symlink_buf:
+	FREE(symlink_buf);
+	return ret;
 }