非血緣關係程序間mmap通訊

建立乙個讀檔案 mmap_r.c

#include

#include
#include
#include
#include
#include
#include
struct stu
;void
sys_err
(char
*str)
intmain
(int argc,
char
*ar**)
fd =
open
(ar**[1]
,o_rdonly);if
(fd ==-1
)sys_err
("open error");
mm =
mmap
(null
,sizeof
(student)
,prot_read,map_shared,fd,0)
;if(mm == map_failed)
sys_err
("mmap error");
close
(fd)
;while(1
)munmap
(mm,
sizeof
(student));
return0;
}

#include

#include
#include
#include
#include
#include
#include
struct stu
;void
sys_err
(char
*str)
intmain
(int argc,
char
*ar**)
;struct stu *mm;
if(argc <2)
fd =
open
(ar**[1]
,o_rdwr | o_creat,
0664);
ftruncate
(fd,
sizeof
(student));
mm =
mmap
(null
,sizeof
(student)
, prot_read|prot_write, map_shared, fd,0)
;if(mm == map_failed)
sys_err
("mmap error");
close
(fd)
;while(1
)munmap
(mm,
sizeof
(student));
return0;
}

1.分別編譯兩個檔案

2.先執行寫檔案 ./mmap_w file_shared

3.再開啟乙個終端，執行讀檔案 ./mmap_r file_shared

從結果可以看出，寫端一直在覆蓋原來的id，讀端一直在讀取file_shared中的內容。

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