Experimental Linux GUI based on web browser

LinuxGUI/Ventoy2Disk/Lib/exfat/src/libexfat/lookup.c

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+/*
+	lookup.c (02.09.09)
+	exFAT file system implementation library.
+
+	Free exFAT implementation.
+	Copyright (C) 2010-2018  Andrew Nayenko
+
+	This program 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 2 of the License, or
+	(at your option) any later version.
+
+	This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+	51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "exfat.h"
+#include <string.h>
+#include <errno.h>
+#include <inttypes.h>
+
+int exfat_opendir(struct exfat* ef, struct exfat_node* dir,
+		struct exfat_iterator* it)
+{
+	int rc;
+
+	exfat_get_node(dir);
+	it->parent = dir;
+	it->current = NULL;
+	rc = exfat_cache_directory(ef, dir);
+	if (rc != 0)
+		exfat_put_node(ef, dir);
+	return rc;
+}
+
+void exfat_closedir(struct exfat* ef, struct exfat_iterator* it)
+{
+	exfat_put_node(ef, it->parent);
+	it->parent = NULL;
+	it->current = NULL;
+}
+
+struct exfat_node* exfat_readdir(struct exfat_iterator* it)
+{
+	if (it->current == NULL)
+		it->current = it->parent->child;
+	else
+		it->current = it->current->next;
+
+	if (it->current != NULL)
+		return exfat_get_node(it->current);
+	else
+		return NULL;
+}
+
+static int compare_char(struct exfat* ef, uint16_t a, uint16_t b)
+{
+	return (int) ef->upcase[a] - (int) ef->upcase[b];
+}
+
+static int compare_name(struct exfat* ef, const le16_t* a, const le16_t* b)
+{
+	while (le16_to_cpu(*a) && le16_to_cpu(*b))
+	{
+		int rc = compare_char(ef, le16_to_cpu(*a), le16_to_cpu(*b));
+		if (rc != 0)
+			return rc;
+		a++;
+		b++;
+	}
+	return compare_char(ef, le16_to_cpu(*a), le16_to_cpu(*b));
+}
+
+static int lookup_name(struct exfat* ef, struct exfat_node* parent,
+		struct exfat_node** node, const char* name, size_t n)
+{
+	struct exfat_iterator it;
+	le16_t buffer[EXFAT_NAME_MAX + 1];
+	int rc;
+
+	*node = NULL;
+
+	rc = utf8_to_utf16(buffer, name, EXFAT_NAME_MAX + 1, n);
+	if (rc != 0)
+		return rc;
+
+	rc = exfat_opendir(ef, parent, &it);
+	if (rc != 0)
+		return rc;
+	while ((*node = exfat_readdir(&it)))
+	{
+		if (compare_name(ef, buffer, (*node)->name) == 0)
+		{
+			exfat_closedir(ef, &it);
+			return 0;
+		}
+		exfat_put_node(ef, *node);
+	}
+	exfat_closedir(ef, &it);
+	return -ENOENT;
+}
+
+static size_t get_comp(const char* path, const char** comp)
+{
+	const char* end;
+
+	*comp = path + strspn(path, "/");				/* skip leading slashes */
+	end = strchr(*comp, '/');
+	if (end == NULL)
+		return strlen(*comp);
+	else
+		return end - *comp;
+}
+
+int exfat_lookup(struct exfat* ef, struct exfat_node** node,
+		const char* path)
+{
+	struct exfat_node* parent;
+	const char* p;
+	size_t n;
+	int rc;
+
+	/* start from the root directory */
+	parent = *node = exfat_get_node(ef->root);
+	for (p = path; (n = get_comp(p, &p)); p += n)
+	{
+		if (n == 1 && *p == '.')				/* skip "." component */
+			continue;
+		rc = lookup_name(ef, parent, node, p, n);
+		if (rc != 0)
+		{
+			exfat_put_node(ef, parent);
+			return rc;
+		}
+		exfat_put_node(ef, parent);
+		parent = *node;
+	}
+	return 0;
+}
+
+static bool is_last_comp(const char* comp, size_t length)
+{
+	const char* p = comp + length;
+
+	return get_comp(p, &p) == 0;
+}
+
+static bool is_allowed(const char* comp, size_t length)
+{
+	size_t i;
+
+	for (i = 0; i < length; i++)
+		switch (comp[i])
+		{
+		case 0x01 ... 0x1f:
+		case '/':
+		case '\\':
+		case ':':
+		case '*':
+		case '?':
+		case '"':
+		case '<':
+		case '>':
+		case '|':
+			return false;
+		}
+	return true;
+}
+
+int exfat_split(struct exfat* ef, struct exfat_node** parent,
+		struct exfat_node** node, le16_t* name, const char* path)
+{
+	const char* p;
+	size_t n;
+	int rc;
+
+	memset(name, 0, (EXFAT_NAME_MAX + 1) * sizeof(le16_t));
+	*parent = *node = exfat_get_node(ef->root);
+	for (p = path; (n = get_comp(p, &p)); p += n)
+	{
+		if (n == 1 && *p == '.')
+			continue;
+		if (is_last_comp(p, n))
+		{
+			if (!is_allowed(p, n))
+			{
+				/* contains characters that are not allowed */
+				exfat_put_node(ef, *parent);
+				return -ENOENT;
+			}
+			rc = utf8_to_utf16(name, p, EXFAT_NAME_MAX + 1, n);
+			if (rc != 0)
+			{
+				exfat_put_node(ef, *parent);
+				return rc;
+			}
+
+			rc = lookup_name(ef, *parent, node, p, n);
+			if (rc != 0 && rc != -ENOENT)
+			{
+				exfat_put_node(ef, *parent);
+				return rc;
+			}
+			return 0;
+		}
+		rc = lookup_name(ef, *parent, node, p, n);
+		if (rc != 0)
+		{
+			exfat_put_node(ef, *parent);
+			return rc;
+		}
+		exfat_put_node(ef, *parent);
+		*parent = *node;
+	}
+	exfat_bug("impossible");
+
+    return 1;
+}