184 lines
7.3 KiB
C
184 lines
7.3 KiB
C
#pragma once
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#include "fs.h"
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#include "stdint.h"
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#include "stddef.h"
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/**
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* Those structures aimes to represent VFS directory entries in memory.
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* It's the equivalent of the Linux dentry or SimpleOs sos_fs_nscache_node.
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*/
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/**
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* Path or Pascal String
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* */
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struct pstr {
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size_t len;
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const char *name;
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};
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#define PSTR_INIT(n, l) \
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{ \
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.len = l, .name = n \
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}
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#define PSTR_STATIC_INIT(n) \
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{ \
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.len = sizeof(n) - 1, .name = n \
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}
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/**
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* @brief Structure representing a file system entry.
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*
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* This structure holds information about a file system entry,
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* including its name, associated inode, relationships within
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* the file system hierarchy, and reference count.
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*/
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struct fs_entry {
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struct pstr name;
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struct inode *node;
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struct fs_entry *parent; // parent directory
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struct fs_entry *mountpoint; // if this is a mounted fs, point to mountpoint
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struct fs_entry *mountedFs; // Fs possibly mounted on this fsEntry
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struct fs_entry *childs; // point to the list of children
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struct fs_entry *nextSiblings, *prevSiblings; // Sibling at the same level
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uint ref; // reference counter
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};
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/**
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* @brief Splits a pstr path into upper and lower components.
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*
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* This function takes a path and splits it into an upper component
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* (the first segment of the path) and a lower component (the rest of the path).
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*
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* @param path Pointer to the input pstr structure representing the path.
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* @param upper Pointer to the pstr structure to store the upper component.
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* @param lower Pointer to the pstr structure to store the lower component.
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* @return bool_t Returns true if there is a lower component, false otherwise.
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*/
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bool_t pstringSplipPath(struct pstr *path, struct pstr *upper, struct pstr *lower);
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/**
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* @brief Compares two pstr structures to check if they are equal.
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*
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* This function compares the length and the content of the strings
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* in the two provided pstr structures.
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*
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* @param a Pointer to the first pstr structure.
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* @param b Pointer to the second pstr structure.
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* @return int Returns 1 if the structures are equal, 0 otherwise.
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*/
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bool_t pstringIsEq(const struct pstr *p1, const struct pstr *p2);
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/**
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* @brief Checks if a pstr structure matches a given C string.
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*
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* @param s Pointer to the null-terminated C string to compare.
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* @return bool_t Returns true if the pstr matches the C string, false otherwise.
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*/
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bool_t pstringIsStr(const struct pstr *p, char *s);
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/**
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* @brief Increments the reference count of a file system entry.
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*
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* This function increments the reference count of the given file system
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* entry. It is typically used to manage the lifecycle of file system
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* entries, ensuring that they are not prematurely deallocated.
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*
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* @param entry Pointer to the fsEntry structure whose reference count will be incremented.
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* @return int Returns 0 on success.
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*/
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int fsEntryRef(struct fs_entry *entry);
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/**
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* @brief Decrements the reference count of a file system entry.
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*
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* This function decrements the reference count of the given file system
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* entry. It is typically used to manage the lifecycle of file system
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* entries, ensuring that they are not prematurely deallocated.
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*
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* @param entry Pointer to the fsEntry structure whose reference count will be decremented.
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* @return int Returns 0 on success.
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*/
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int fsEntryUnref(struct fs_entry **entry);
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/**
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* @brief Allocates and initializes a new fsEntry.
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*
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* This function allocates memory for a new `fsEntry` structure, initializes
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* it with the provided name and inode, and adds it to the parent's list of children.
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*
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* @param parent Pointer to the parent `fsEntry` structure. Can be NULL if the new entry has no parent.
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* @param name Pointer to the `pstr` structure representing the name of the new entry. Can be NULL.
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* @param inode Pointer to the `inode` structure associated with the new entry.
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*
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* @return struct fsEntry* Pointer to the newly allocated `fsEntry` structure, or NULL if allocation fails.
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*
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* @note The reference count of the new entry is set to 1.
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* @note If a parent is provided, the new entry is added to the parent's list of children and the parent's reference count is incremented.
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* @note The inode's reference count is incremented.
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*/
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struct fs_entry *fsEntryAlloc(struct fs_entry *parent, const struct pstr *name, struct inode *inode);
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/**
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* @brief Looks up an entry in the file system.
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*
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* This function searches for a specified entry within the children
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* of a given directory entry. The search is limited to the entries
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* that are already in memory. If the entry is not found, it indicates
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* that the entry must be resolved using disk accesses.
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*
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* @param entry The node in which we are looking for the entry.
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* @param name The name of the entry we are looking for.
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* @param root The base node beyond which lookup must not go (to
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* support chroot): a kind of "barrier".
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* @param result The fsEntry for the given entry (set only when
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* the return value is 0).
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*
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* @return int Returns 0 if the entry is found, otherwise returns a non-zero error code.
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* -ENOENT if the entry could not be found in the entry directory.
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*
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* @note The mountpoints are followed.
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* @note result is a NEW reference to the node. It should be unreferenced when unused.
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*/
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int fsEntryLookup(struct fs_entry *entry, const struct pstr *name,
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const struct fs_entry *root, struct fs_entry **result);
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/**
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* @brief Setup the fsEntry subsystem
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*
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*/
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int fsEntrySetup(void);
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/**
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* @brief Mounts a file system entry at a specified mount point.
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*
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* This function mounts a file system entry (`mounted`) at a specified mount point (`mountpoint`).
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* It updates the `mountedFs` field of the mount point and the `mountpoint` field of the mounted entry.
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*
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* @param mountpoint Pointer to the `fsEntry` structure representing the mount point.
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* @param mounted Pointer to the `fsEntry` structure representing the file system entry to be mounted.
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*
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* @return int Returns 0 on success, or -EBUSY if either the mount point is already occupied or the mounted entry is already mounted.
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*
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* @note The reference counts of both the mount point and the mounted entry are incremented.
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*/
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int fsEntryMount(struct fs_entry *mountpoint, struct fs_entry *mounted);
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/**
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* @brief Unmounts a file system entry.
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*
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* This function unmounts a file system entry (`mounted`) from its mount point.
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* It updates the `mountedFs` field of the mount point and the `mountpoint` field of the mounted entry.
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*
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* @param mounted Pointer to the `fsEntry` structure representing the file system entry to be unmounted.
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*
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* @return int Returns 0 on success, -ENOENT if the entry is not mounted, or -EBUSY if the entry is busy.
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*
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* @note The unmount operation fails if the mounted entry has children or other references.
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* @note The reference counts of both the mount point and the mounted entry are decremented.
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*/
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int fsEntryUmount(struct fs_entry *mounted);
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