int yaffs_open_sharing()

in fs/yaffs2/yaffsfs.c [774:995]

• 163 lines of code
• 71 McCabe index (conditional complexity)

int yaffs_open_sharing(const YCHAR *path, int oflag, int mode, int sharing)
{
	struct yaffs_obj *obj = NULL;
	struct yaffs_obj *dir = NULL;
	YCHAR *name;
	int handle = -1;
	struct yaffsfs_FileDes *fd = NULL;
	int openDenied = 0;
	int symDepth = 0;
	int errorReported = 0;
	int rwflags = oflag & (O_RDWR | O_RDONLY | O_WRONLY);
	u8 shareRead = (sharing & YAFFS_SHARE_READ) ? 1 : 0;
	u8 shareWrite = (sharing & YAFFS_SHARE_WRITE) ? 1 : 0;
	u8 sharedReadAllowed;
	u8 sharedWriteAllowed;
	u8 alreadyReading;
	u8 alreadyWriting;
	u8 readRequested;
	u8 writeRequested;
	int notDir = 0;
	int loop = 0;

	if (!path) {
		yaffsfs_SetError(-EFAULT);
		return -1;
	}

	if (yaffsfs_CheckPath(path) < 0) {
		yaffsfs_SetError(-ENAMETOOLONG);
		return -1;
	}

	/* O_EXCL only has meaning if O_CREAT is specified */
	if (!(oflag & O_CREAT))
		oflag &= ~(O_EXCL);

	/* O_TRUNC has no meaning if (O_CREAT | O_EXCL) is specified */
	if ((oflag & O_CREAT) & (oflag & O_EXCL))
		oflag &= ~(O_TRUNC);

	/* Todo: Are there any more flag combos to sanitise ? */

	/* Figure out if reading or writing is requested */

	readRequested = (rwflags == O_RDWR || rwflags == O_RDONLY) ? 1 : 0;
	writeRequested = (rwflags == O_RDWR || rwflags == O_WRONLY) ? 1 : 0;

	yaffsfs_Lock();

	handle = yaffsfs_NewHandleAndFileDes();

	if (handle < 0) {
		yaffsfs_SetError(-ENFILE);
		errorReported = 1;
	} else {

		fd = yaffsfs_HandleToFileDes(handle);

		/* try to find the exisiting object */
		obj = yaffsfs_FindObject(NULL, path, 0, 1, NULL, NULL, NULL);

		obj = yaffsfs_FollowLink(obj, symDepth++, &loop);

		if (obj &&
		    obj->variant_type != YAFFS_OBJECT_TYPE_FILE &&
		    obj->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY)
			obj = NULL;

		if (obj) {

			/* The file already exists or it might be a directory */

			/* A directory can't be opened as a file */
			if (obj->variant_type == YAFFS_OBJECT_TYPE_DIRECTORY) {
				openDenied = 1;
				yaffsfs_SetError(-EISDIR);
				errorReported = 1;
			}

			/* Open should fail if O_CREAT and O_EXCL are specified
			 * for a file that exists.
			 */
			if (!errorReported &&
			    (oflag & O_EXCL) && (oflag & O_CREAT)) {
				openDenied = 1;
				yaffsfs_SetError(-EEXIST);
				errorReported = 1;
			}

			/* Check file permissions */
			if (readRequested && !(obj->yst_mode & S_IREAD))
				openDenied = 1;

			if (writeRequested && !(obj->yst_mode & S_IWRITE))
				openDenied = 1;

			if (!errorReported && writeRequested &&
			    obj->my_dev->read_only) {
				openDenied = 1;
				yaffsfs_SetError(-EROFS);
				errorReported = 1;
			}

			if (openDenied && !errorReported) {
				yaffsfs_SetError(-EACCES);
				errorReported = 1;
			}

			/* Check sharing of an existing object. */
			if (!openDenied) {
				struct yaffsfs_FileDes *fdx;
				int i;

				sharedReadAllowed = 1;
				sharedWriteAllowed = 1;
				alreadyReading = 0;
				alreadyWriting = 0;
				for (i = 0; i < YAFFSFS_N_HANDLES; i++) {
					fdx = &yaffsfs_fd[i];
					if (fdx->handleCount > 0 &&
					    fdx->inodeId >= 0 &&
					    yaffsfs_inode[fdx->inodeId].iObj
					    == obj) {
						if (!fdx->shareRead)
							sharedReadAllowed = 0;
						if (!fdx->shareWrite)
							sharedWriteAllowed = 0;
						if (fdx->reading)
							alreadyReading = 1;
						if (fdx->writing)
							alreadyWriting = 1;
					}
				}

				if ((!sharedReadAllowed && readRequested) ||
				    (!shareRead && alreadyReading) ||
				    (!sharedWriteAllowed && writeRequested) ||
				    (!shareWrite && alreadyWriting)) {
					openDenied = 1;
					yaffsfs_SetError(-EBUSY);
					errorReported = 1;
				}
			}

		}

		/* If we could not open an existing object, then let's see if
		 * the directory exists. If not, error.
		 */
		if (!obj && !errorReported) {
			dir = yaffsfs_FindDirectory(NULL, path, &name, 0,
						    &notDir, &loop);
			if (!dir && notDir) {
				yaffsfs_SetError(-ENOTDIR);
				errorReported = 1;
			} else if (loop) {
				yaffsfs_SetError(-ELOOP);
				errorReported = 1;
			} else if (!dir) {
				yaffsfs_SetError(-ENOENT);
				errorReported = 1;
			}
		}

		if (!obj && dir && !errorReported && (oflag & O_CREAT)) {
			/* Let's see if we can create this file */
			if (dir->my_dev->read_only) {
				yaffsfs_SetError(-EROFS);
				errorReported = 1;
			} else if (yaffsfs_TooManyObjects(dir->my_dev)) {
				yaffsfs_SetError(-ENFILE);
				errorReported = 1;
			} else
				obj = yaffs_create_file(dir, name, mode, 0, 0);

			if (!obj && !errorReported) {
				yaffsfs_SetError(-ENOSPC);
				errorReported = 1;
			}
		}

		if (!obj && dir && !errorReported && !(oflag & O_CREAT)) {
			yaffsfs_SetError(-ENOENT);
			errorReported = 1;
		}

		if (obj && !openDenied) {
			int inodeId = yaffsfs_GetInodeIdForObject(obj);

			if (inodeId < 0) {
				/*
				 * Todo: Fix any problem if inodes run out,
				 * That can't happen if the number of inode
				 * items >= number of handles.
				 */
			}

			fd->inodeId = inodeId;
			fd->reading = readRequested;
			fd->writing = writeRequested;
			fd->append = (oflag & O_APPEND) ? 1 : 0;
			fd->position = 0;
			fd->shareRead = shareRead;
			fd->shareWrite = shareWrite;

			/* Hook inode to object */
			obj->my_inode = (void *)&yaffsfs_inode[inodeId];

			if ((oflag & O_TRUNC) && fd->writing)
				yaffs_resize_file(obj, 0);
		} else {
			yaffsfs_PutHandle(handle);
			if (!errorReported)
				yaffsfs_SetError(0);	/* Problem */
			handle = -1;
		}
	}

	yaffsfs_Unlock();

	return handle;
}