Open System Services System Calls Reference Manual (G06.29+, H06.08+, J06.03+)

System Functions (f - i) fork(2)
ERRORS
If any of the following conditions occurs, the fork() function sets errno to the corresponding
value:
[EACCES] Open for execute access on the code file or any library file was denied.
[EAGAIN] System resources such as disk space, process control block (PCB) space, MAP-
POOL space, stack space, or PFS space are temporarily inadequate.
[EIO] Some physical input or output error has occurred. Either a file cannot be opened
because of an input or output error or data has been lost during an input or output
transfer. This value is used only for errors on the object file of a loaded program
or library, or during data transfer with a Guardian environment home terminal.
[ENOMEM] Required resources are not available. Subsequent calls to the same function will
not succeed for the same reason.
Possible causes of this error include insufficient primary memory (stack, globals,
or heap) for the new process.
[ENOTOSS] The calling process is not an OSS process. The fork() function cannot be called
from the Guardian environment.
[EUNKNOWN]
Unknown error. An unrecognized or very obscure error occurred. If this error
occurs, follow site-defined procedures for reporting software problems to
HP.
RELATED INFORMATION
Functions: exec(2), _exit(2), exit(3), raise(3), semop(2), shmat(2), sigaction(2), spt_fork(2),
tdm_execve(2), tdm_execvep(2), tdm_fork(2), tdm_spawn(2), tdm_spawnp(2), times(3),
ulimit(3), umask(2), wait(2).
STANDARDS CONFORMANCE
The POSIX standards leave some features to the implementing vendor to define. The following
features are affected in the HP implementation:
• The child process shares directory streams with the parent. They share the same block of
directory entries, but each stream can be used by only one of the processes.
• Guardian attributes are associated with the new OSS process. See Guardian Attributes
under DESCRIPTION.
The following are HP extensions to the XPG4 Version 2 specification:
• The [EFAULT], [ENOTOSS], and [EUNKNOWN] error values are HP extensions.
The use of this function with the POSIX User Thread Model library conforms to the following
industry standards:
• IEEE Std 1003.1-2004, POSIX System Application Program Interface
This function does not conform to the async-signal safe requirement of the POSIX.1 standard.
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