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

Porting UNIX Applications to the OSS Environment
Open System Services Porting Guide—520573-006
7-6
Using Functional Equivalents
These practices are primarily applicable to new programs, but you may get an
opportunity to apply them when porting existing UNIX programs.
Using Functional Equivalents
The fewer nonstandard functions used by a program, the more portable it is. A
program becomes increasingly more difficult to port to multiple environments as it uses
functions in more of the categories in the order listed below:
•
ISO/ANSI C
•
POSIX.1
•
POSIX.2
•
XPG3
•
XPG4
•
XPG4 Version 2
•
Single UNIX Specification
•
HP extensions to OSS functions
•
HP extension OSS functions
•
Guardian functions
When a program uses nonstandard functions not in the set of functions included in
ISO/ANSI C, POSIX.1, or XPG4, functionally equivalent functions must be used when
porting the program to the OSS environment. The suggested list of functionally
equivalent functions listed in Table 7-1 can be used if the program uses one of the
nonstandard functions listed in the “Function” column.
The functions listed under “Function” in Table 7-1 are not currently provided in the OSS
environment. Therefore, they must be replaced by the functionally equivalent functions
(“Replacement Recommendation”).
Table 7-1. Functions Currently Not in the OSS Environment (page 1 of 2)
Function Replacement Recommendation
alloca() Use malloc() and free().
cabs() Use sqrt(x*x + y*y).
flock() Use fcntl().
getpw() Use getpwent().
gettimeofday() Use localtime() and time().
killpg() Use kill() with a negative process group ID.
lchown() Do not use.
lockf() Use fcntl().
mmap(), munmap() Recode in ISO/ANSI C.
poll() Use Guardian sockets with nowait I/O.
scandir() Use readdir(), malloc(), and qsort().
setbuffer() Use setvbuf().