fs: exfat: Import libexfat from fuse-exfat

Import most of libexfat from [1] except for log.c verbatim. The code
does not even compile and further adjustments and integration into
U-Boot filesystem code is in the next patch.

[1] https://github.com/relan/exfat
    0b41c6d3560d ("CI: bump FreeBSD to 13.1.")

Acked-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Marek Vasut <marex@denx.de>
diff --git a/fs/exfat/io.c b/fs/exfat/io.c
new file mode 100644
index 0000000..7af5316
--- /dev/null
+++ b/fs/exfat/io.c
@@ -0,0 +1,514 @@
+/*
+	io.c (02.09.09)
+	exFAT file system implementation library.
+
+	Free exFAT implementation.
+	Copyright (C) 2010-2023  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 <inttypes.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#if defined(__APPLE__)
+#include <sys/disk.h>
+#elif defined(__OpenBSD__)
+#include <sys/param.h>
+#include <sys/disklabel.h>
+#include <sys/dkio.h>
+#include <sys/ioctl.h>
+#elif defined(__NetBSD__)
+#include <sys/ioctl.h>
+#elif __linux__
+#include <sys/mount.h>
+#endif
+#ifdef USE_UBLIO
+#include <sys/uio.h>
+#include <ublio.h>
+#endif
+
+struct exfat_dev
+{
+	int fd;
+	enum exfat_mode mode;
+	off_t size; /* in bytes */
+#ifdef USE_UBLIO
+	off_t pos;
+	ublio_filehandle_t ufh;
+#endif
+};
+
+static bool is_open(int fd)
+{
+	return fcntl(fd, F_GETFD) != -1;
+}
+
+static int open_ro(const char* spec)
+{
+	return open(spec, O_RDONLY);
+}
+
+static int open_rw(const char* spec)
+{
+	int fd = open(spec, O_RDWR);
+#ifdef __linux__
+	int ro = 0;
+
+	/*
+	   This ioctl is needed because after "blockdev --setro" kernel still
+	   allows to open the device in read-write mode but fails writes.
+	*/
+	if (fd != -1 && ioctl(fd, BLKROGET, &ro) == 0 && ro)
+	{
+		close(fd);
+		errno = EROFS;
+		return -1;
+	}
+#endif
+	return fd;
+}
+
+struct exfat_dev* exfat_open(const char* spec, enum exfat_mode mode)
+{
+	struct exfat_dev* dev;
+	struct stat stbuf;
+#ifdef USE_UBLIO
+	struct ublio_param up;
+#endif
+
+	/* The system allocates file descriptors sequentially. If we have been
+	   started with stdin (0), stdout (1) or stderr (2) closed, the system
+	   will give us descriptor 0, 1 or 2 later when we open block device,
+	   FUSE communication pipe, etc. As a result, functions using stdin,
+	   stdout or stderr will actually work with a different thing and can
+	   corrupt it. Protect descriptors 0, 1 and 2 from such misuse. */
+	while (!is_open(STDIN_FILENO)
+		|| !is_open(STDOUT_FILENO)
+		|| !is_open(STDERR_FILENO))
+	{
+		/* we don't need those descriptors, let them leak */
+		if (open("/dev/null", O_RDWR) == -1)
+		{
+			exfat_error("failed to open /dev/null");
+			return NULL;
+		}
+	}
+
+	dev = malloc(sizeof(struct exfat_dev));
+	if (dev == NULL)
+	{
+		exfat_error("failed to allocate memory for device structure");
+		return NULL;
+	}
+
+	switch (mode)
+	{
+	case EXFAT_MODE_RO:
+		dev->fd = open_ro(spec);
+		if (dev->fd == -1)
+		{
+			free(dev);
+			exfat_error("failed to open '%s' in read-only mode: %s", spec,
+					strerror(errno));
+			return NULL;
+		}
+		dev->mode = EXFAT_MODE_RO;
+		break;
+	case EXFAT_MODE_RW:
+		dev->fd = open_rw(spec);
+		if (dev->fd == -1)
+		{
+			free(dev);
+			exfat_error("failed to open '%s' in read-write mode: %s", spec,
+					strerror(errno));
+			return NULL;
+		}
+		dev->mode = EXFAT_MODE_RW;
+		break;
+	case EXFAT_MODE_ANY:
+		dev->fd = open_rw(spec);
+		if (dev->fd != -1)
+		{
+			dev->mode = EXFAT_MODE_RW;
+			break;
+		}
+		dev->fd = open_ro(spec);
+		if (dev->fd != -1)
+		{
+			dev->mode = EXFAT_MODE_RO;
+			exfat_warn("'%s' is write-protected, mounting read-only", spec);
+			break;
+		}
+		free(dev);
+		exfat_error("failed to open '%s': %s", spec, strerror(errno));
+		return NULL;
+	}
+
+	if (fstat(dev->fd, &stbuf) != 0)
+	{
+		close(dev->fd);
+		free(dev);
+		exfat_error("failed to fstat '%s'", spec);
+		return NULL;
+	}
+	if (!S_ISBLK(stbuf.st_mode) &&
+		!S_ISCHR(stbuf.st_mode) &&
+		!S_ISREG(stbuf.st_mode))
+	{
+		close(dev->fd);
+		free(dev);
+		exfat_error("'%s' is neither a device, nor a regular file", spec);
+		return NULL;
+	}
+
+#if defined(__APPLE__)
+	if (!S_ISREG(stbuf.st_mode))
+	{
+		uint32_t block_size = 0;
+		uint64_t blocks = 0;
+
+		if (ioctl(dev->fd, DKIOCGETBLOCKSIZE, &block_size) != 0)
+		{
+			close(dev->fd);
+			free(dev);
+			exfat_error("failed to get block size");
+			return NULL;
+		}
+		if (ioctl(dev->fd, DKIOCGETBLOCKCOUNT, &blocks) != 0)
+		{
+			close(dev->fd);
+			free(dev);
+			exfat_error("failed to get blocks count");
+			return NULL;
+		}
+		dev->size = blocks * block_size;
+	}
+	else
+#elif defined(__OpenBSD__)
+	if (!S_ISREG(stbuf.st_mode))
+	{
+		struct disklabel lab;
+		struct partition* pp;
+		char* partition;
+
+		if (ioctl(dev->fd, DIOCGDINFO, &lab) == -1)
+		{
+			close(dev->fd);
+			free(dev);
+			exfat_error("failed to get disklabel");
+			return NULL;
+		}
+
+		/* Don't need to check that partition letter is valid as we won't get
+		   this far otherwise. */
+		partition = strchr(spec, '\0') - 1;
+		pp = &(lab.d_partitions[*partition - 'a']);
+		dev->size = DL_GETPSIZE(pp) * lab.d_secsize;
+
+		if (pp->p_fstype != FS_NTFS)
+			exfat_warn("partition type is not 0x07 (NTFS/exFAT); "
+					"you can fix this with fdisk(8)");
+	}
+	else
+#elif defined(__NetBSD__)
+	if (!S_ISREG(stbuf.st_mode))
+	{
+		off_t size;
+
+		if (ioctl(dev->fd, DIOCGMEDIASIZE, &size) == -1)
+		{
+			close(dev->fd);
+			free(dev);
+			exfat_error("failed to get media size");
+			return NULL;
+		}
+		dev->size = size;
+	}
+	else
+#endif
+	{
+		/* works for Linux, FreeBSD, Solaris */
+		dev->size = exfat_seek(dev, 0, SEEK_END);
+		if (dev->size <= 0)
+		{
+			close(dev->fd);
+			free(dev);
+			exfat_error("failed to get size of '%s'", spec);
+			return NULL;
+		}
+		if (exfat_seek(dev, 0, SEEK_SET) == -1)
+		{
+			close(dev->fd);
+			free(dev);
+			exfat_error("failed to seek to the beginning of '%s'", spec);
+			return NULL;
+		}
+	}
+
+#ifdef USE_UBLIO
+	memset(&up, 0, sizeof(struct ublio_param));
+	up.up_blocksize = 256 * 1024;
+	up.up_items = 64;
+	up.up_grace = 32;
+	up.up_priv = &dev->fd;
+
+	dev->pos = 0;
+	dev->ufh = ublio_open(&up);
+	if (dev->ufh == NULL)
+	{
+		close(dev->fd);
+		free(dev);
+		exfat_error("failed to initialize ublio");
+		return NULL;
+	}
+#endif
+
+	return dev;
+}
+
+int exfat_close(struct exfat_dev* dev)
+{
+	int rc = 0;
+
+#ifdef USE_UBLIO
+	if (ublio_close(dev->ufh) != 0)
+	{
+		exfat_error("failed to close ublio");
+		rc = -EIO;
+	}
+#endif
+	if (close(dev->fd) != 0)
+	{
+		exfat_error("failed to close device: %s", strerror(errno));
+		rc = -EIO;
+	}
+	free(dev);
+	return rc;
+}
+
+int exfat_fsync(struct exfat_dev* dev)
+{
+	int rc = 0;
+
+#ifdef USE_UBLIO
+	if (ublio_fsync(dev->ufh) != 0)
+	{
+		exfat_error("ublio fsync failed");
+		rc = -EIO;
+	}
+#endif
+	if (fsync(dev->fd) != 0)
+	{
+		exfat_error("fsync failed: %s", strerror(errno));
+		rc = -EIO;
+	}
+	return rc;
+}
+
+enum exfat_mode exfat_get_mode(const struct exfat_dev* dev)
+{
+	return dev->mode;
+}
+
+off_t exfat_get_size(const struct exfat_dev* dev)
+{
+	return dev->size;
+}
+
+off_t exfat_seek(struct exfat_dev* dev, off_t offset, int whence)
+{
+#ifdef USE_UBLIO
+	/* XXX SEEK_CUR will be handled incorrectly */
+	return dev->pos = lseek(dev->fd, offset, whence);
+#else
+	return lseek(dev->fd, offset, whence);
+#endif
+}
+
+ssize_t exfat_read(struct exfat_dev* dev, void* buffer, size_t size)
+{
+#ifdef USE_UBLIO
+	ssize_t result = ublio_pread(dev->ufh, buffer, size, dev->pos);
+	if (result >= 0)
+		dev->pos += size;
+	return result;
+#else
+	return read(dev->fd, buffer, size);
+#endif
+}
+
+ssize_t exfat_write(struct exfat_dev* dev, const void* buffer, size_t size)
+{
+#ifdef USE_UBLIO
+	ssize_t result = ublio_pwrite(dev->ufh, (void*) buffer, size, dev->pos);
+	if (result >= 0)
+		dev->pos += size;
+	return result;
+#else
+	return write(dev->fd, buffer, size);
+#endif
+}
+
+ssize_t exfat_pread(struct exfat_dev* dev, void* buffer, size_t size,
+		off_t offset)
+{
+#ifdef USE_UBLIO
+	return ublio_pread(dev->ufh, buffer, size, offset);
+#else
+	return pread(dev->fd, buffer, size, offset);
+#endif
+}
+
+ssize_t exfat_pwrite(struct exfat_dev* dev, const void* buffer, size_t size,
+		off_t offset)
+{
+#ifdef USE_UBLIO
+	return ublio_pwrite(dev->ufh, (void*) buffer, size, offset);
+#else
+	return pwrite(dev->fd, buffer, size, offset);
+#endif
+}
+
+ssize_t exfat_generic_pread(const struct exfat* ef, struct exfat_node* node,
+		void* buffer, size_t size, off_t offset)
+{
+	uint64_t uoffset = offset;
+	cluster_t cluster;
+	char* bufp = buffer;
+	off_t lsize, loffset, remainder;
+
+	if (offset < 0)
+		return -EINVAL;
+	if (uoffset >= node->size)
+		return 0;
+	if (size == 0)
+		return 0;
+
+	if (uoffset + size > node->valid_size)
+	{
+		ssize_t bytes = 0;
+
+		if (uoffset < node->valid_size)
+		{
+			bytes = exfat_generic_pread(ef, node, buffer,
+					node->valid_size - uoffset, offset);
+			if (bytes < 0 || (size_t) bytes < node->valid_size - uoffset)
+				return bytes;
+		}
+		memset(buffer + bytes, 0,
+				MIN(size - bytes, node->size - node->valid_size));
+		return MIN(size, node->size - uoffset);
+	}
+
+	cluster = exfat_advance_cluster(ef, node, uoffset / CLUSTER_SIZE(*ef->sb));
+	if (CLUSTER_INVALID(*ef->sb, cluster))
+	{
+		exfat_error("invalid cluster 0x%x while reading", cluster);
+		return -EIO;
+	}
+
+	loffset = uoffset % CLUSTER_SIZE(*ef->sb);
+	remainder = MIN(size, node->size - uoffset);
+	while (remainder > 0)
+	{
+		if (CLUSTER_INVALID(*ef->sb, cluster))
+		{
+			exfat_error("invalid cluster 0x%x while reading", cluster);
+			return -EIO;
+		}
+		lsize = MIN(CLUSTER_SIZE(*ef->sb) - loffset, remainder);
+		if (exfat_pread(ef->dev, bufp, lsize,
+					exfat_c2o(ef, cluster) + loffset) < 0)
+		{
+			exfat_error("failed to read cluster %#x", cluster);
+			return -EIO;
+		}
+		bufp += lsize;
+		loffset = 0;
+		remainder -= lsize;
+		cluster = exfat_next_cluster(ef, node, cluster);
+	}
+	if (!(node->attrib & EXFAT_ATTRIB_DIR) && !ef->ro && !ef->noatime)
+		exfat_update_atime(node);
+	return MIN(size, node->size - uoffset) - remainder;
+}
+
+ssize_t exfat_generic_pwrite(struct exfat* ef, struct exfat_node* node,
+		const void* buffer, size_t size, off_t offset)
+{
+	uint64_t uoffset = offset;
+	int rc;
+	cluster_t cluster;
+	const char* bufp = buffer;
+	off_t lsize, loffset, remainder;
+
+	if (offset < 0)
+		return -EINVAL;
+	if (uoffset > node->size)
+	{
+		rc = exfat_truncate(ef, node, uoffset, true);
+		if (rc != 0)
+			return rc;
+	}
+	if (uoffset + size > node->size)
+	{
+		rc = exfat_truncate(ef, node, uoffset + size, false);
+		if (rc != 0)
+			return rc;
+	}
+	if (size == 0)
+		return 0;
+
+	cluster = exfat_advance_cluster(ef, node, uoffset / CLUSTER_SIZE(*ef->sb));
+	if (CLUSTER_INVALID(*ef->sb, cluster))
+	{
+		exfat_error("invalid cluster 0x%x while writing", cluster);
+		return -EIO;
+	}
+
+	loffset = uoffset % CLUSTER_SIZE(*ef->sb);
+	remainder = size;
+	while (remainder > 0)
+	{
+		if (CLUSTER_INVALID(*ef->sb, cluster))
+		{
+			exfat_error("invalid cluster 0x%x while writing", cluster);
+			return -EIO;
+		}
+		lsize = MIN(CLUSTER_SIZE(*ef->sb) - loffset, remainder);
+		if (exfat_pwrite(ef->dev, bufp, lsize,
+				exfat_c2o(ef, cluster) + loffset) < 0)
+		{
+			exfat_error("failed to write cluster %#x", cluster);
+			return -EIO;
+		}
+		bufp += lsize;
+		loffset = 0;
+		remainder -= lsize;
+		node->valid_size = MAX(node->valid_size, uoffset + size - remainder);
+		cluster = exfat_next_cluster(ef, node, cluster);
+	}
+	if (!(node->attrib & EXFAT_ATTRIB_DIR))
+		/* directory's mtime should be updated by the caller only when it
+		   creates or removes something in this directory */
+		exfat_update_mtime(node);
+	return size - remainder;
+}