---

   mmap.3p    ( 3 )

---

Использование в приложениях (Application usage)

Use of mmap() may reduce the amount of memory available to other
       memory allocation functions.

       Use of MAP_FIXED may result in unspecified behavior in further
       use of malloc() and shmat().  The use of MAP_FIXED is
       discouraged, as it may prevent an implementation from making the
       most effective use of resources. Most implementations require
       that off and addr are multiples of the page size as returned by
       sysconf().

       The application must ensure correct synchronization when using
       mmap() in conjunction with any other file access method, such as
       read() and write(), standard input/output, and shmat().

       The mmap() function allows access to resources via address space
       manipulations, instead of read()/write().  Once a file is mapped,
       all a process has to do to access it is use the data at the
       address to which the file was mapped. So, using pseudo-code to
       illustrate the way in which an existing program might be changed
       to use mmap(), the following:

           fildes = open(...)
           lseek(fildes, some_offset)
           read(fildes, buf, len)
           /* Use data in buf. */

       becomes:

           fildes = open(...)
           address = mmap(0, len, PROT_READ, MAP_PRIVATE, fildes, some_offset)
           /* Use data at address. */