I am playing with the Swift for z/OS beta. Swift itself supports little in the
way of I/O, and instead depends on the underlying C runtime. Below is a small
program that opens a file, reads 4 bytes in to a buffer and writes out the
results as an integer.
import Libc
func fwx(file filename: String, access: String) {
if let fwf = fopen(filename, access) {
defer { fclose(fwf) }
let buffer = UnsafeMutablePointer<UInt32>.allocate(capacity: 1)
defer { buffer.deallocate(capacity: 1) }
let _ = fread(buffer, MemoryLayout<UInt32>.size, 1, fwf)
print("from \(filename): \(buffer.pointee)")
}
else {
print("error opening file \(filename): \(errno)")
}
}
fwx(file: "/u/dvfjs/fw.bin", access: "rb")
fwx(file: "//'DVFJS.FW'", access: "rb")
fwx(file: "dd:FW", access: "rb")
The last three statements are the "mainline" of the program. For the first one
the file is a Unix file. For the second one its a VSAM ESDS called 'DVFJS.FW'.
Both of these work. I can't figure out how to specify a DD reference to make
that last one work. I've tried both using "dd:FW" and "//dd:FW". Is it
perhaps a problem with the DD itself? When running it under BPXBATCH I am
specifying the FW DD like I would for any other batch job:
//SHELL JOB NOTIFY=&SYSUID,REGION=2000M
//UNIXSH EXEC PGM=BPXBATCH,PARMDD=PARMSIN
//FW DD DISP=SHR,DSN=DVFJS.FW
//PARMSIN DD *
SH /u/dvfjs/src/fw
/*
//STDIN DD DUMMY
//STDOUT DD SYSOUT=*
//STDERR DD SYSOUT=*
//STDENV DD DUMMY
//
Does the Unix environment for BPXBATCH not have access to the JCL DD?
We don't have a license for the C compiler, so I've never used C for z/OS.
Frank
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