Open System Services Porting Guide (G06.24+, H06.03+)

Porting UNIX Applications to the OSS Environment
Open System Services Porting Guide—520573-006
7-24
Using OSS Function Calls
The behavior of these function calls is as expected in POSIX-compliant environments,
except for some side effects specific to the HP environment. It is not possible to
migrate a process to another processor using either fork() or the exec set of
functions, but it is possible to do this using the tdm_execve set of functions. The
tdm_execve set of functions is discussed more in Using HP Extensions on page 7-25.
One side effect of using the exec set of functions is that the process handle is
changed. After successful operation of the fork() call, the initial position within an
EDIT file opened by a call to the OSS open() function is the same for both the parent
and the child processes. Changing the position used by one process, however, does
not change the position used by the other process.
Using the exit() Function
The exit() function call can be issued by either an OSS process or a Guardian
process. If the parent process is an OSS process, the normal SIGCHLD signal is sent
to notify the parent process of the death of one of its child processes. Child processes
of a terminated process are assigned a parent process ID of 1.
Using the kill() Function
The target of a kill() function call must be an OSS process or group of OSS
processes. kill() cannot send signals to Guardian processes because they do not
have OSS process IDs. Additional restrictions are imposed by the Safeguard security
mechanism on the sending of signals if Safeguard protection is used on OSS
processes. OSS processes can catch all of the normal kill() signals defined in the
XPG4 specifications.
Table 7-2. Process Attributes for fork() and exec Set of Functions
fork() exec Set of Functions
Same program file New program file
New OSS process ID Same OSS process ID
Copies parent data space New data space
Retains parent arg and env
parameters
Installs new arg and env parameters
Inherits open files Controlled file open propagation
Inherits signal handlers No signal handler
Same processor only Same processor only; processor migration with
tdm_execve set of functions
New process handle New process handle
Shared memory segments inherited No shared memory segments inherited
No breakpoints inherited No breakpoints inherited