Re: open FIFO erro

On 2006-09-25, freegnu <freegnu@xxxxxxx> wrote:
hi all , i have a test program, which the prarent process write "hello
world" to a FIFO , and the child process read it form the FIFO,and printf it
on the screem.
but when i run the test program, it open the FIFO,there some problem happen.
the prarent process hand up on open(), and
the child process has error take place


You must open the fifo for reading before you attempt to write to it for writing.

man 3 mkfifo
man 4 fifo



It's probably safest to open it before the fork and then close the reader
in the fork where it's not needed.

also.

if(EEXIST == errno)printf("pEEXIST\n");
if(EACCES == errno)printf("pEACCES\n");
if(EROFS == errno)printf("pEROFS\n");
if(EFAULT == errno)printf("pEFAULT\n");
if(EINVAL == errno)printf("pEINVAL\n");
if(ENAMETOOLONG == errno)printf("pENAMETOOLONG\n");
if(ENOTDIR == errno)printf("pENOTDIR\n");
if(ENOMEM == errno)printf("pENOMEM\n");
if(ELOOP == errno)printf("pELOOP\n");
if(EIO == errno)printf("pEIO\n");


there's a neat standard function called "perror()"


this one may be worth a look too.

man 2 pipe

Bye.
Jasen
.

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