Some remarks:
- C auto variables, as in this case, are not initialized on entry to a
function. That is, the content is unknown, maybe zero or any other value.
The use of this uninitialized variable is a program error and did not show
up on the prior releases of z/OS, as it seems. It is not ok to blame the
new release of the OS for this ... which is done sometimes. The program
is in error (has always been) and has to be fixed.
- the z/OS compiler has options to do initialization of auto variables,
AFAIK
(at least I know that the PL/1 compiler has such options), but I do not
recommend
to use such options, because it generates performance problems
- some smart compilers generate warnings, when uninitialized variables are
used. To do that, static analysis of the program flow has to be done to some
extent; this works more or less good, so these warnings are sometimes
correct,
sometimes not. If the compilers I use support such warnings, I would
suggest
to switch them on (the PL/1 compiler does this, and it saved me from
lots of errors
in the last years).
Kind regards
Bernd
Am 23.06.2014 21:53, schrieb Gibney, Dave:
Thank you, I only rarely C. Changing these two lines to have the zero
initialization
int in_cnt=0, out_cnt=0;
int incrmt=0, inc=0, blnk_cnt=0, recout_siz=0, FEOF=0;
returned the program to working. And I know the was some re-arranging of where
initial memory would be allocated between 11 and 13.
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]]
On Behalf Of Sam Siegel
Sent: Monday, June 23, 2014 12:45 PM
To: [email protected]
Subject: Re: C program stopped working with z/OS 1.13 on production rollout
of z/OS 1.13 :(
Several variables, including FEOF, are not explicitly initialized to 0.
The program appears to set FEOF to 1 only when there is an error opening
either of the DDs.
There may be residual data on the stack which is setting FEOF to a non-zero
value.
I don't think the C standard requires the compiler or runtime to ensure any
particular value to non-initialized variables.
Sam
On Mon, Jun 23, 2014 at 12:12 PM, Gibney, Dave <[email protected]> wrote:
I have a C program, written by someone long gone, last complied in
2004 or so. Running under z/OS 1.13, it reports reading/writing zero
records.
STEPLIB of CEE.SCEERUN from z/OS 1.11 returns it to its previous
working behavior.
I am opening a PMR next, but thought I would ask here also. Entire
program follows
/* This program works like the Unix tf -d command. It removes the */
/* special character (hex 4f) from records, thus leaving a clean, */
/* comma-delimited record in the output file. */
/* */
/* Modified 04/08/2004 by DMD; force abend if write error detected*/
/* Modified 08/23/2004 by DMD; remove carriage return & line feed.*/
/* */
#include <stdio.h>
#include <string.h>
#define MAXREC 5000
main (){
int rec_in_cnt;
int rec_out_cnt;
char rec_in[MAXREC];
char rec_out[MAXREC];
char delimitr[1]={0x00};
char comma [1]=",";
char NL [1]={0x15}; /* new-line */
char CR [1]={0x0D}; /* carriage return */
char blnks[5000];
FILE * File_Out;
FILE * File_In;
int in_cnt, out_cnt;
int incrmt, inc, blnk_cnt, recout_siz, FEOF;
for (inc=0;inc<MAXREC;inc++) blnks[inc]=0x40; /* init blank array */
File_In = fopen("dd:stdin","rb,recfm=*,type=record");
if (!File_In){
printf("\n Could not open file STDIN. %d.\n",ferror);
FEOF=1; } /* force exit */
File_Out = fopen("dd:stdout","wb,recfm=*,type=record");
if (!File_Out){
printf("\n Could not open file STDOUT. %d.\n,ferror");
FEOF=1; } /* force exit */
while ( (! feof(File_In)) && (!FEOF) ){
in_cnt = fread(rec_in,sizeof(char),MAXREC,File_In);
for(inc=0;inc<in_cnt;inc++)rec_out[inc]=0x40; /* clean buff-out */
if (! feof(File_In)) {
rec_in_cnt++;
if ( !ferror(File_In) ){
for (incrmt=0,inc=0,blnk_cnt=0;incrmt<in_cnt;incrmt++) {
if (strncmp(&rec_in[incrmt],delimitr,1)) /* if ! fill char */
if (strncmp(&rec_in[incrmt],blnks,1)){ /* if ! fill blnk */
if(!(strncmp(&rec_in[incrmt],comma,1))) /* if is comma */
blnk_cnt=0; /* drop prev blnks*/
else {
memcpy(&rec_out[inc],&blnks[1],blnk_cnt); /* do blnk */
inc+=blnk_cnt; blnk_cnt=0; /* save & reset cnt */
} /* end of ELSE condition */
if ( (strncmp(&rec_in[incrmt],NL,1)) /* not newline */
&& (strncmp(&rec_in[incrmt],CR,1)) ) /* not car-rtn */
memcpy(&rec_out[inc++],&rec_in[incrmt],1); /* do char */
else memcpy(&rec_out[inc++],&blnks[1],1); /* blank it */
}
else blnk_cnt++; /* count the blank */
} /* end of FOR loop */
recout_siz = fwrite(rec_out,sizeof(char),in_cnt,File_Out);
if (recout_siz < in_cnt) { /* if we didn't write whole record */
printf("Write error encountered."); /* for example B37. */
abort(); /* force abend. */
}
rec_out_cnt++;
} /* end of IF ferror condition */
else printf("\n Error reading input file.\n");
} /* end of IF feof condition */
} /* end of WHILE condition */
printf("Record counts for data compression utility GNDU2200.\n\n");
printf("Records read %d.\nRecords written
%d.",rec_in_cnt,rec_out_cnt); fclose(File_In); fclose(File_Out); }
/* end of MAIN */
Dave Gibney
Information Technology Services
Washington State University
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