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Add the code for reading a file. Write the root file initialization.

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This commit is contained in:
Enrico Fraccaroli
2021-12-15 18:57:52 +01:00
parent 7d74ab6bce
commit 73ef08dc11
2 changed files with 172 additions and 39 deletions
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mentos/src/fs/ext2.c
+171 -39
View File
@@ -28,18 +28,32 @@
#define EXT2_MAX_SYMLINK_COUNT 8 ///< Maximum nesting of symlinks, used to prevent a loop.
#define EXT2_NAME_LEN 255 ///< The lenght of names inside directory entries.
#define EXT2_S_IRWXO 0x0007 ///< -------rwx : Others can read/write/execute
#define EXT2_S_IXOTH 0x0001 ///< ---------x : Others can execute
#define EXT2_S_IWOTH 0x0002 ///< --------w- : Others can write
#define EXT2_S_IROTH 0x0004 ///< -------r-- : Others can read
#define EXT2_S_IRWXG 0x0038 ///< -------rwx : Group can read/write/execute
#define EXT2_S_IXGRP 0x0008 ///< ------x--- : Group can execute
#define EXT2_S_IWGRP 0x0010 ///< -----w---- : Group can write
#define EXT2_S_IRGRP 0x0020 ///< ----r----- : Group can read
#define EXT2_S_IRWXU 0x01C0 ///< -------rwx : User can read/write/execute
#define EXT2_S_IXUSR 0x0040 ///< ---x------ : User can execute
#define EXT2_S_IWUSR 0x0080 ///< --w------- : User can write
// File types.
#define EXT2_S_IFMT 0xF000 ///< Format mask
#define EXT2_S_IFSOCK 0xC000 ///< Socket
#define EXT2_S_IFLNK 0xA000 ///< Symbolic link
#define EXT2_S_IFREG 0x8000 ///< Regular file
#define EXT2_S_IFBLK 0x6000 ///< Block device
#define EXT2_S_IFDIR 0x4000 ///< Directory
#define EXT2_S_IFCHR 0x2000 ///< Character device
#define EXT2_S_IFIFO 0x1000 ///< Fifo
// Permissions bit.
#define EXT2_S_ISUID 0x0800 ///< SUID
#define EXT2_S_ISGID 0x0400 ///< SGID
#define EXT2_S_ISVTX 0x0200 ///< Sticky Bit
#define EXT2_S_IRWXU 0x01C0 ///< rwx------- : User can read/write/execute
#define EXT2_S_IRUSR 0x0100 ///< -r-------- : User can read
#define EXT2_S_IWUSR 0x0080 ///< --w------- : User can write
#define EXT2_S_IXUSR 0x0040 ///< ---x------ : User can execute
#define EXT2_S_IRWXG 0x0038 ///< ----rwx--- : Group can read/write/execute
#define EXT2_S_IRGRP 0x0020 ///< ----r----- : Group can read
#define EXT2_S_IWGRP 0x0010 ///< -----w---- : Group can write
#define EXT2_S_IXGRP 0x0008 ///< ------x--- : Group can execute
#define EXT2_S_IRWXO 0x0007 ///< -------rwx : Others can read/write/execute
#define EXT2_S_IROTH 0x0004 ///< -------r-- : Others can read
#define EXT2_S_IWOTH 0x0002 ///< --------w- : Others can write
#define EXT2_S_IXOTH 0x0001 ///< ---------x : Others can execute
typedef enum ext2_block_status_t {
ext2_block_status_free = 0, ///< The block is free.
@@ -960,6 +974,108 @@ static ssize_t ext2_read_inode_block(ext2_filesystem_t *fs, ext2_inode_t *inode,
return ext2_read_block(fs, real_index, buffer);
}
static ssize_t ext2_read(vfs_file_t *file, char *buffer, off_t offset, size_t nbyte)
{
// Get the filesystem.
ext2_filesystem_t *fs = (ext2_filesystem_t *)file->device;
if (fs == NULL) {
pr_err("The file does not belong to an EXT2 filesystem (%s).\n", file->name);
return -1;
}
// Get the inode associated with the file.
ext2_inode_t inode;
if (ext2_read_inode(fs, &inode, file->ino) == -1) {
pr_err("Failed to read the inode (%s).\n", file->name);
return -1;
}
// Check if the file is empty.
if (inode.size == 0)
return 0;
uint32_t end;
if ((offset + nbyte) > inode.size) {
end = inode.size;
} else {
end = offset + nbyte;
}
uint32_t start_block = offset / fs->block_size;
uint32_t end_block = end / fs->block_size;
uint32_t end_size = end - end_block * fs->block_size;
uint32_t size_to_read = end - offset;
if (start_block == end_block) {
// Read the real block.
ext2_read_inode_block(fs, &inode, start_block, fs->block_buffer);
// Copy the content back to the buffer.
memcpy(buffer, (uint8_t *)(((uintptr_t)fs->block_buffer) + ((uintptr_t)offset % fs->block_size)), size_to_read);
} else {
uint32_t block_offset;
uint32_t blocks_read = 0;
for (block_offset = start_block; block_offset < end_block; block_offset++, blocks_read++) {
if (block_offset == start_block) {
ext2_read_inode_block(fs, &inode, block_offset, fs->block_buffer);
memcpy(buffer, (uint8_t *)(((uintptr_t)fs->block_buffer) + ((uintptr_t)offset % fs->block_size)), fs->block_size - (offset % fs->block_size));
} else {
ext2_read_inode_block(fs, &inode, block_offset, fs->block_buffer);
memcpy(buffer + fs->block_size * blocks_read - (offset % fs->block_size), fs->block_buffer, fs->block_size);
}
}
if (end_size) {
ext2_read_inode_block(fs, &inode, end_block, fs->block_buffer);
memcpy(buffer + fs->block_size * blocks_read - (offset % fs->block_size), fs->block_buffer, end_size);
}
}
return size_to_read;
}
static int ext2_set_root(ext2_filesystem_t *fs, ext2_inode_t *inode)
{
// Information for root dir.
fs->root->device = (void *)fs;
fs->root->ino = 2;
fs->root->name[0] = '/';
fs->root->name[1] = '\0';
// Information from the inode.
fs->root->uid = inode->uid;
fs->root->gid = inode->gid;
fs->root->length = inode->size;
fs->root->mask = inode->mode & 0xFFF;
fs->root->nlink = inode->links_count;
// File flags.
fs->root->flags = 0;
if ((inode->mode & EXT2_S_IFREG) == EXT2_S_IFREG) {
pr_err("The root inode is a regular file.\n");
kmem_cache_free(fs->root);
return -1;
}
if ((inode->mode & EXT2_S_IFDIR) == EXT2_S_IFDIR) {
fs->root->flags |= DT_DIR;
} else {
pr_err("The root inode is not a directory.\n");
kmem_cache_free(fs->root);
return -1;
}
if ((inode->mode & EXT2_S_IFBLK) == EXT2_S_IFBLK) {
fs->root->flags |= DT_BLK;
}
if ((inode->mode & EXT2_S_IFCHR) == EXT2_S_IFCHR) {
fs->root->flags |= DT_CHR;
}
if ((inode->mode & EXT2_S_IFIFO) == EXT2_S_IFIFO) {
fs->root->flags |= DT_FIFO;
}
if ((inode->mode & EXT2_S_IFLNK) == EXT2_S_IFLNK) {
fs->root->flags |= DT_LNK;
}
fs->root->atime = inode->atime;
fs->root->mtime = inode->mtime;
fs->root->ctime = inode->ctime;
fs->root->sys_operations = NULL;
fs->root->fs_operations = NULL;
list_head_init(&fs->root->siblings);
return 0;
}
static vfs_file_t *ext2_mount(vfs_file_t *block_device)
{
// Create the ext2 filesystem.
@@ -973,17 +1089,15 @@ static vfs_file_t *ext2_mount(vfs_file_t *block_device)
// Read the superblock.
if (ext2_read_superblock(fs) == -1) {
pr_err("Failed to read the superblock table at 1024.\n");
// Free the memory occupied by the filesystem.
kfree(fs);
return NULL;
// Free just the filesystem.
goto free_filesystem;
}
// Check the superblock magic number.
if (fs->superblock.magic != EXT2_SUPERBLOCK_MAGIC) {
pr_err("Wrong magic number, it is not an EXT2 filesystem.\n");
ext2_dump_superblock(&fs->superblock);
// Free the memory occupied by the filesystem.
kfree(fs);
return NULL;
// Free just the filesystem.
goto free_filesystem;
}
// Compute the volume size.
fs->block_size = 1024U << fs->superblock.log_block_size;
@@ -1035,30 +1149,23 @@ static vfs_file_t *ext2_mount(vfs_file_t *block_device)
fs->block_groups = kmalloc(fs->block_size * fs->bgdt_length);
if (fs->block_groups == NULL) {
pr_err("Failed to allocate memory for the block buffer.\n");
// Free the memory occupied by the filesystem.
kfree(fs);
return NULL;
// Free just the filesystem.
goto free_filesystem;
}
// Try to read the BGDT.
if (ext2_read_bgdt(fs) == -1) {
pr_err("Failed to read the BGDT.\n");
// Free the memory occupied by the block groups.
kfree(fs->block_groups);
// Free the memory occupied by the filesystem.
kfree(fs);
return NULL;
// Free the block_groups and the filesystem.
goto free_block_groups;
}
// Preentively allocate a buffer for reading blocks.
fs->block_buffer = kmalloc(fs->block_size * sizeof(char));
if (fs->block_buffer == NULL) {
pr_err("Failed to allocate memory for the block buffer.\n");
// Free the memory occupied by the block groups.
kfree(fs->block_groups);
// Free the memory occupied by the filesystem.
kfree(fs);
return NULL;
// Free the block_groups and the filesystem.
goto free_block_groups;
}
memset(fs->block_buffer, 0, sizeof(char) * fs->block_size);
@@ -1066,16 +1173,34 @@ static vfs_file_t *ext2_mount(vfs_file_t *block_device)
fs->inode_buffer = kmalloc(fs->superblock.inode_size * sizeof(char));
if (fs->inode_buffer == NULL) {
pr_err("Failed to allocate memory for the block buffer.\n");
// Free the memory occupied by the block buffer.
kfree(fs->block_buffer);
// Free the memory occupied by the block groups.
kfree(fs->block_groups);
// Free the memory occupied by the filesystem.
kfree(fs);
return NULL;
// Free the block_buffer, the block_groups and the filesystem.
goto free_block_buffer;
}
memset(fs->inode_buffer, 0, sizeof(char) * fs->superblock.inode_size);
// We need the root inode in order to set the root file.
ext2_inode_t root_inode;
if (ext2_read_inode(fs, &root_inode, 2U) == -1) {
pr_err("Failed to set the root inode.\n");
// Free the block_buffer, the block_groups and the filesystem.
goto free_inode_buffer;
}
// Allocate the memory for the root.
fs->root = kmem_cache_alloc(vfs_file_cache, GFP_KERNEL);
if (!fs->root) {
pr_err("Failed to allocate memory for the EXT2 root file!\n");
// Free the block_buffer, the block_groups and the filesystem.
goto free_inode_buffer;
}
if (ext2_set_root(fs, &root_inode) == -1) {
pr_err("Failed to set the EXT2 root.\n");
// Free the block_buffer, the block_groups and the filesystem.
goto free_all;
}
pr_notice("Mounted EXT2 disk, root VFS node is at 0x%x.\n", (uintptr_t)fs->root);
// Dump the filesystem details for debugging.
ext2_dump_filesystem(fs);
// Dump the superblock details for debugging.
@@ -1083,12 +1208,19 @@ static vfs_file_t *ext2_mount(vfs_file_t *block_device)
// Dump the block group descriptor table.
ext2_dump_bgdt(fs);
// Free the memory occupied by the block buffer.
kfree(fs->block_buffer);
free_all:
// Free the memory occupied by the root.
kmem_cache_free(fs->root);
free_inode_buffer:
// Free the memory occupied by the inode buffer.
kfree(fs->inode_buffer);
free_block_buffer:
// Free the memory occupied by the block buffer.
kfree(fs->block_buffer);
free_block_groups:
// Free the memory occupied by the block groups.
kfree(fs->block_groups);
free_filesystem:
// Free the memory occupied by the filesystem.
kfree(fs);
return NULL;
mentos/src/fs/procfs.c
+1
View File
@@ -602,6 +602,7 @@ static inline vfs_file_t *procfs_create_file_struct(procfs_file_t *procfs_file)
file->flags = procfs_file->flags;
file->sys_operations = &procfs_sys_operations;
file->fs_operations = &procfs_fs_operations;
list_head_init(&file->siblings);
//pr_debug("procfs_create_file_struct(%p): VFS file : %p\n", procfs_file, file);
return file;
}