From 78e51a8c6678b6e3dff3d619aa786669f531f4bc Mon Sep 17 00:00:00 2001 From: rsc Date: Fri, 14 Jan 2005 03:45:44 +0000 Subject: checkpoint --- man/man3/9p-file.html | 258 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 258 insertions(+) create mode 100644 man/man3/9p-file.html (limited to 'man/man3/9p-file.html') diff --git a/man/man3/9p-file.html b/man/man3/9p-file.html new file mode 100644 index 00000000..63ae5042 --- /dev/null +++ b/man/man3/9p-file.html @@ -0,0 +1,258 @@ + +9p-file(3) - Plan 9 from User Space + + + + +
+
+
9P-FILE(3)9P-FILE(3) +
+
+

NAME
+ +
+ + Tree, alloctree, freetree, File, createfile, closefile, removefile, + walkfile, opendirfile, readdirfile, closedirfile, hasperm – in-memory + file hierarchy
+ +
+

SYNOPSIS
+ +
+ + #include <u.h>
+ #include <libc.h>
+ #include <fcall.h>
+ #include <thread.h>
+ #include <9p.h>
+ +
+ + typedef struct File
+ {
+ +
+ + +
+ + Ref;
+ Dir;
+ void*aux;
+ +
+ +
+ +
+ + +
+ + ...
+ +
+ +
+ } File;
+ +
+ + typedef struct Tree
+ {
+ +
+ + +
+ + File *root;
+ +
+ +
+ +
+ + +
+ + ...
+ +
+ +
+ } Tree;
+ +
+ + Tree*      alloctree(char *uid, char *gid, ulong mode,
+ +
+ + +
+ + void (*destroy)(File*))
+ +
+ +
+ void       freetree(Tree *tree)
+ File*      createfile(File *dir, char *name, char *uid,
+ +
+ + +
+ + ulong mode, void *aux)
+ +
+ +
+ int        removefile(File *file)
+ void       closefile(File *file)
+ File*      walkfile(File *dir, char *path)
+ Readdir* opendirfile(File *dir)
+ long       readdirfile(Readdir *rdir, char *buf, long n)
+ void       closedirfile(Readdir *rdir)
+ int        hasperm(File *file, char *uid, int p)
+ +
+

DESCRIPTION
+ +
+ + Files and Trees provide an in-memory file hierarchy intended for + use in 9P file servers. +
+ + Alloctree creates a new tree of files, and freetree destroys it. + The root of the tree (also the root element in the structure) + will have mode mode and be owned by user uid and group gid. Destroy + is used when freeing File structures and is described later. +
+ + Files (including directories) other than the root are created + using createfile, which attempts to create a file named name in + the directory dir. If created, the file will have owner uid and + have a group inherited from the directory. Mode and the permissions + of dir are used to calculate the permission bits for the file + as + described in open(9p). It is permissible for name to be a slash-separated + path rather than a single element. +
+ + Removefile removes a file from the file tree. The file will not + be freed until the last reference to it has been removed. Directories + may only be removed when empty. Removefile returns zero on success, + –1 on error. It is correct to consider removefile to be closefile + with the side effect of removing the file when possible. +
+ + Walkfile evaluates path relative to the directory dir, returning + the resulting file, or zero if the named file or any intermediate + element does not exist. +
+ + The File structure’s aux pointer may be used by the client for + per-File storage. Files are reference-counted: if not zero, destroy + (specified in the call to alloctree) will be called for each file + when its last reference is removed or when the tree is freed. + Destroy should take care of any necessary cleanup related to + aux. When creating new file references by copying pointers, call + incref (see lock(3)) to update the reference count. To note the + removal of a reference to a file, call closefile. Createfile and + walkfile return new references. Removefile, closefile, and walkfile + (but not createfile) consume the passed reference. +
+ + Directories may be read, yielding a directory entry structure + (see stat(9p)) for each file in the directory. In order to allow + concurrent reading of directories, clients must obtain a Readdir + structure by calling opendirfile on a directory. Subsequent calls + to readdirfile will each yield an integral number of machine- + independent stat buffers, until end of directory. When finished, + call closedirfile to free the Readdir. +
+ + Hasperm does simplistic permission checking; it assumes only one-user + groups named by uid and returns non-zero if uid has permission + p (a bitwise-or of AREAD, AWRITE and AEXEC) according to file−>mode. + 9P servers written using File trees will do standard permission + checks automatically; hasperm may be + called explicitly to do additional checks. A 9P server may link + against a different hasperm implementation to provide more complex + groups.
+ +
+

EXAMPLE
+ +
+ + The following code correctly handles references when elementwise + walking a path and creating a file.
+ +
+ + f = tree−>root;
+ incref(f);
+ for(i=0; i<n && f!=nil; i++)
+ +
+ + f = walkfile(f, elem[i]);
+ +
+ if(f == nil)
+ +
+ + return nil;
+ +
+ nf = createfile(f, "foo", "nls", 0666, nil);
+ closefile(f);
+ return nf;
+ +
+ +
+

SOURCE
+ +
+ + /usr/local/plan9/src/lib9p/file.c
+ +
+

SEE ALSO
+ +
+ + 9p(3)
+ +
+

BUGS
+ +
+ + The reference counting is cumbersome.
+ +
+ +

 +
+
+ + +
+
+
+Space Glenda +
+
+ + -- cgit v1.2.3