pfopen.c File Reference

Implements the DNX Client logging functions. More...

#include "pfopen.h"
#include "dnxDebug.h"
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/wait.h>
#include <assert.h>

Go to the source code of this file.

Defines
#define	elemcount(x)   (sizeof(x)/sizeof(*(x)))
Functions
PFILE *	pfopen (const char *cmdstring, const char *type)
	Open a child process whose STDIO is redirected to the parent.
int	pfclose (PFILE *pfile)
	Close an existing PFILE object.
int	pfkill (PFILE *pfile, int sig)
	Kill a set of processes associated with an existing PFILE object.

---

Detailed Description

Implements the DNX Client logging functions.

Author:

Robert W. Ingraham (dnx-devel@lists.sourceforge.net)

John Calcote (dnx-devel@lists.sourceforge.net)

Attention:

Please submit patches to http://dnx.sourceforge.net

Definition in file pfopen.c.

---

Define Documentation

#define elemcount

(

x

)

(sizeof(x)/sizeof(*(x)))

Definition at line 44 of file pfopen.c.

---

Function Documentation

int pfclose

(

PFILE *

pfile

)

Close an existing PFILE object.

Closes all open pipe handles, and then waits for the associated child process to die, returning the status value of the child process.

Parameters:

[in]

pfile

- the process pipe to be closed.

Returns:

The value of the waitpid system call's stat_loc parameter, or the status of the child processed waited for using the waitpid system call.

Note:

Because the return value of this routine is the stat_loc value of the waitpid system call, any of the W* macros defined for use on this value by the system may be used to query the status of the associated child process.

Definition at line 212 of file pfopen.c.

References _pfile_::fp, _pfile_::pid, and xfree.

Referenced by dnxPluginExternal().

int pfkill	(	PFILE *	pfile,
		int	sig
	)

Kill a set of processes associated with an existing PFILE object.

Parameters:

[in]	pfile	- the pipe representing the process to be killed.
[in]	sig	- the signal to send the process.

Returns:

Zero on success, or -1 on error, and the global errno is set.

Definition at line 247 of file pfopen.c.

References _pfile_::pid.

Referenced by dnxPluginExternal().

PFILE* pfopen	(	const char *	cmdstring,
		const char *	type
	)

Open a child process whose STDIO is redirected to the parent.

The STDOUT, STDERR, and (optionally) STDIN file handles for the child process are available to the parent (the calling process) to be used in any appropriate manner.

The only allowable modes for the pipe are 'read' and 'write' as specified by the type parameter in the form of a single 'r' or 'w' character string. A 'r' channel is read-only and can only be used to gather data from the child process. A 'w' channel can also be used to send data to the child process.

We use (up to) three pipes for communication. According to POSIX.1g it's not specified whether you can write to the read end of a pipe, or vice-versa; pipes are defined as half-duplex. Thus, we need to open a separate pipe (pair of file descriptors) for each channel. While full- duplex pipes are probably available everywhere, it's not in the spec, so it's not portable.

• First Pipe:
  • pfd[0] The parent reads stdout data from the child.
  • pfd[1] The child writes stdout data to the parent.
• Second Pipe:
  • pfd[2] The parent reads stderr data from the child.
  • pfd[3] The child writes stderr data to the parent.
• Third Pipe (optional - *type == 'w'):
  • pfd[4] The child reads stdin data from the parent.
  • pfd[5] The parent writes stdin data to the child.

Parameters:

[in]	cmdstring	- the command string executed as a child process.
[in]	type	- the file type string used when opening the I/O channel to the child process.

Returns:

A newly allocated PFILE object reference. This object may be queried or closed using the other calls defined in this module. If this routine returns 0, it indicates an error and errno is set appropriately.

Definition at line 93 of file pfopen.c.

References elemcount, _pfile_::fp, _pfile_::pid, xcalloc, and xfree.

Referenced by dnxPluginExternal().