NAME

Pcreate, Pxcreate, Pcreate_callback — create and control a process

LIBRARY

Process Control Library (libproc, -lproc)

SYNOPSIS

#include <libproc.h>

struct ps_prochandle *
Pcreate(const char *file, char *const *argv, int *perr, char *path, size_t len);

struct ps_prochandle *
Pxcreate(const char *file, char *const *argv, char *const *envp, int *perr, char *path, size_t len);

void
Pcreate_callback(struct ps_prochandle *P);

DESCRIPTION

The Pcreate() function creates a process controlled by the libproc library. The Pxcreate() function does the same while also allowing the replacement of the environment via envp.

Both functions cause the caller to fork(2). Followed by the child calling exec(2) to load the new process image specified by file. The PATH is searched for file if it is not an absolute path, similar to execvp(2).

The process image will be invoked with the arguments specified by argv, which should be a NULL-terminated array of character strings. Each entry in the array is an individual argument. The environment of the process image will be inherited from the running process if the Pcreate() function is called or if the Pxcreate() function is called and the value of envp is NULL. Otherwise, envp should be a NULL-terminated array of character strings whose entries are in the form of key=value. For more on the process environment, see environ(7).

The Pcreate_callback() function allows a way for callers to inject a callback into the child process before the call to exec(2). The symbol Pcreate_callback is a symbol that may be interposed on by consumers. It allows the chance for the modification of signal dispositions or any other changes that a caller may wish to make.

If the caller's real user or group ID is not their effective user or group ID, then the child process's user and group IDs will all be reset to the real user and group id.

The perr argument must be a non-NULL pointer. If the Pcreate() or Pxcreate() functions fail, the value pointed to will be filled in with a more detailed error code listed in ERRORS. A human-readable error message is obtained with Pcreate_error(3PROC).

Multiple executables named file may exist on the PATH. To determine the full path of the executable pass a non-NULL path pointer. Upon successful completion of Pcreate() or Pxcreate() the path pointer will contain the full path up to len bytes, including the NUL character.

Upon successful completion of the Pcreate() or Pxcreate() function, a handle to the process is returned. This handle is usable with other libproc routines and will persist until either Pfree(3PROC) or Prelease(3PROC) is called on the resulting handle. The process created is stopped just after return from the exec(2) family of system calls. The process will not run, unless the caller sets it running or releases its handle to the process.

A 32-bit process cannot use this interface to launch or control a 64-bit process. However, a 64-bit process can create and control both 32-bit and 64-bit processes.

RETURN VALUES

Upon successful completion, both the Pcreate() and Pxcreate() functions create a new process and return a libproc handle to it. Otherwise, NULL is returned and perr is filled in with the corresponding error.

ERRORS

The Pcreate() and Pxcreate() functions will fail if:

C_FORK: The call to fork(2) failed.
C_INTR: The operation was interrupted by a signal.
C_LP64: The calling process is 32-bit, but it attempted to control a 64-bit process.
C_NOEXEC: The specified file or the one found by searching PATH cannot be executed.
C_NOENT: The specified file does not exist or it could not be found by searching PATH.
C_PERM: The specified file or the one found by searching PATH is set-id or unreadable.
C_STRANGE: An unanticipated system error occurred while trying to create the process and its handle. When this occurs, then the value of errno is meaningful. See errno(3C) for more information and Intro(2) for the list of possible errors.

INTERFACE STABILITY

Uncommitted

MT-LEVEL

MT-Safe