bestbarcoder.com

Solaris Doors in Software Include PDF-417 2d barcode in Software Solaris Doors

Solaris Doors using barcode drawer for software control to generate, create pdf417 image in software applications. GS1 DataBar The kernel door_r Software PDF 417 eturn() code copies the return data back to the caller and places the server thread back in the door server pool. The calling (client) thread, which we left in a sleep state back in door_call(), is set back to an T_ONPROC state, and the shuttle code (shuttle_resume()) is called to give the processor back to the caller and have it resume execution. Some nal points to make regarding doors.

There s a fair amount of code in the kernel doorfs module designed to deal with error conditions and the premature termination of the calling thread or server thread. In general, if the calling thread is awakened early, that is, before door_call() has completed, the code gures out why the wakeup occurred (signal, exit call, etc.) and sends a cancel signal (SIGCANCEL) to the server thread.

If a server thread is interrupted because of a signal, exit, error condition, etc., the door_call() code bails out. In the client, an EINTR (interrupted system call) error will be set, signifying that door_call() terminated prematurely.

. Interprocess Communication Part Four FILES AND FILE SYSTEMS Files and File I/O File System Overview File System Framework The UFS File System File System Caching. Stack read() fwrite() aio read() mmap() write() fread() aiowrite(). Stdio Libraries Async IO Library /dev/rdsk/...

/dev/rdsk/...

. Heap read / write a barcode pdf417 for None io Binary (Data) Binary (Text) Application Memory (HEAP). Special File Sys. (specfs). Regular File Systems ( ufs, vxfs, pcfs etc ) Directory Structures NFS Server File System Blocks seg_drv Directory Name Lookup Cache Meta Data (Inode) Cache File Segment driver (seg_map) direct I/O VNODE Segment driver (seg_vn). Paged VNODE VM Core Old Buffer Cache (BUFHWM) (File System Cache & Page Cache). Block I/O Interface Volume Manager Layer - Disk Suite, VxVM SCSI/Device Driver Framework Data Disks Swap Disk The Solaris File I/O System 11 SOLARIS FILES AND FILE I/O rom its inception, Unix has been built around two fundamental entities: processes and les. Everything that is executed on the system is a process, and all process I/O is done to a le. We saw in previous chapters how the process model has evolved and how the kernel thread is the unit of execution in the Solaris kernel.

The implementation of les and le I/O facilities has also seen some changes since the early versions of UNIX. The notion of a le now includes more abstract types, and the interfaces available for doing le I/O have expanded. In this chapter, we look at the implementation of les in Solaris and discuss some of the abstract le types and the le I/O facilities.

. 11.1 Files in Solaris Generically de ned, a le is an entity that stores data as an array of bytes, beginning at byte zero and extending to the end of the le. The contents of the le (the data) can take any number of forms: a simple text le, a binary executable le, a directory le, etc. Solaris supports many types of les, several of which are de ned at the kernel level, meaning that some component of the kernel has intimate knowledge of the le s format by virtue of the le type.

An example is a directory le on a UFS le system directory les have a speci c format that is known to the UFS kernel routines designed for directory I/O. The number of le types in the kernel has increased over the last several years with the addition new kernel abstractions in the form of pseudo les. Pseudo les.

Solaris Files and File I/O provide a means by which the kernel can abstract as a le a binary object, like a data structure in memory. Users and programmers view the object as a le, in that the traditional le I/O operations are supported on it (for the most part). It s a pseudo le because it is not an on-disk le; it s not a real le in the traditional sense.

Under the covers, the operations performed on the object are managed by the le system on which the le resides. A speci c le type often belongs to an underlying le system that manages the storage and retrieval of the le and de nes the kernel functions for I/O and control operations on the le. ( See 14, The Unix File System ," for details about le systems.

) Table 11-1 lists the various types of les implemented in Solaris. Table 11-1 Solaris File Types File Type Regular File Character Description System Designation UFS A traditional on-disk le. Can be a text le, binary shared object, or executable le.

UFS d A le that stores the names of other les and directories. Other le systems can implement directories within their own le hierarchy. UFS l A le that represents a link to another le, potentially in another directory or on another le system.

specfs c A device special le for devices capable of character mode I/O. Device les represent I/O devices on the system and provide a means of indexing into the device driver and uniquely identifying a speci c device. specfs b As above, a device special le for devices capable of block-mode I/O, such as disk and tape devices fofs p A le that provides a bidirectional communication path between processes running on the same system.

doorfs D Part of the door interprocess communication facility. Doors provide a means of doing very fast interprocess procedure calling and message and data passing..

Copyright © bestbarcoder.com . All rights reserved.