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| Append data to a IFS stream file in RPGLE |
In this article we will discuss how to append data to a ifs stream file i.e. we will start writing the data after the last byte has been written to the existing ifs stream file. Therefore, we will open the ifs file using the specific append flags with the ifs open() C api and will use normal write() api to write/append the data into the existing ifs stream file.
RPGLE program for Append data to a IFS stream file
HDFTACTGRP(*NO)
D close PR 10i 0 extproc('close') *
D fileds 10i 0 value *file descriptor
D write PR 10i 0 extproc('write') * 32 bit, no. of byt
D fileds 10i 0 value *file descriptor
D buffer * value * pointer to byte
D noofbytes 10U 0 value * 32 bits
D open PR 10I 0 extproc('open')
D ifspath * value options(*string) *ifs path
D oflag 10I 0 value *string of 32 bits
D mode 10U 0 value options(*nopass) * 9 bits
D codepage 10U 0 value options(*nopass) *
* <-----oflag---->
D O_readonly C 1
D O_writeonly C 2
D O_readwrite C 4
D O_createfileifnotexist...
D C 8
D O_exclusivecreate...
D C 16
D O_truncateto0bytes...
D C 64
D O_appendtofile C 256
D O_converttextbycodepage...
D C 8388608
D O_openintextmode...
D C 16777216
*
* <-----mode---->
* owner,group,other (RWX)
* owner authority
D M_readowner C 256
D M_writeowner C 128
D M_executeowner C 64
* group authority
D M_readgroup C 32
D M_writegroup C 16
D M_executegroup C 8
* other people
D M_readother C 4
D M_writeother C 2
D M_executeother C 1
*
Difspath s 512a
Doflag s 10I 0
Dmode s 10U 0
Dcodepage s 10U 0
Dfiledescriptor s 10i 0
Difsdata s 11a inz
Dreturn_write s 10i 0 inz
Dreturn_close s 10i 0 inz
C EVAL ifspath = '/home/easyclass/append'
C EVAL oflag = O_writeonly +
C O_createfileifnotexist +
C O_appendtofile
C EVAL mode = M_readowner +
C M_writeowner +
C M_executeowner
C EVAL filedescriptor = open(%trim(ifspath):
C oflag:
C mode)
C IF filedescriptor < 0
C RETURN
C ENDIF
C EVAL ifsdata = 'DATA APPEND'
C EVAL return_write = write(filedescriptor:
C %addr(ifsdata):%size(ifsdata))
C IF return_write < %size(ifsdata)
C RETURN
C ENDIF
C EVAL ifsdata = 'CONTINUED'
C EVAL return_write = write(filedescriptor:
C %addr(ifsdata):%size(ifsdata))
C IF return_write < %size(ifsdata)
C RETURN
C ENDIF
C EVAL return_close = close(filedescriptor)
C IF return_close = -1
C RETURN
C ENDIF
C EVAL *INLR = *ON
C RETURN
HDFTACTGRP(*NO)
D close PR 10i 0 extproc('close') *
D fileds 10i 0 value *file descriptor
D write PR 10i 0 extproc('write') * 32 bit, no. of byt
D fileds 10i 0 value *file descriptor
D buffer * value * pointer to byte
D noofbytes 10U 0 value * 32 bits
D open PR 10I 0 extproc('open')
D ifspath * value options(*string) *ifs path
D oflag 10I 0 value *string of 32 bits
D mode 10U 0 value options(*nopass) * 9 bits
D codepage 10U 0 value options(*nopass) *
* <-----oflag---->
D O_readonly C 1
D O_writeonly C 2
D O_readwrite C 4
D O_createfileifnotexist...
D C 8
D O_exclusivecreate...
D C 16
D O_truncateto0bytes...
D C 64
D O_appendtofile C 256
D O_converttextbycodepage...
D C 8388608
D O_openintextmode...
D C 16777216
*
* <-----mode---->
* owner,group,other (RWX)
* owner authority
D M_readowner C 256
D M_writeowner C 128
D M_executeowner C 64
* group authority
D M_readgroup C 32
D M_writegroup C 16
D M_executegroup C 8
* other people
D M_readother C 4
D M_writeother C 2
D M_executeother C 1
*
Difspath s 512a
Doflag s 10I 0
Dmode s 10U 0
Dcodepage s 10U 0
Dfiledescriptor s 10i 0
Difsdata s 11a inz
Dreturn_write s 10i 0 inz
Dreturn_close s 10i 0 inz
/free
ifspath = '/home/easyclass/append';
oflag = O_writeonly +
O_createfileifnotexist +
O_appendtofile ;
mode =
M_readowner +
M_writeowner +
M_executeowner;
filedescriptor = open(%trim(ifspath):
oflag:
mode);
if filedescriptor < 0;
return;
endif;
ifsdata = 'DATA APPEND';
return_write = write(filedescriptor:%addr(ifsdata):%size(ifsdata));
if return_write < %size(ifsdata);
return;
endif;
ifsdata = 'CONTINUED';
return_write = write(filedescriptor:%addr(ifsdata):%size(ifsdata));
if return_write < %size(ifsdata);
return;
endif;
return_close = close(filedescriptor);
if return_close = -1;
return;
endif;
*inlr = *on;
return;
/end-free
**FREE
CTL-OPT DFTACTGRP(*NO);
DCL-PR close int(10) EXTPROC('close');
fileds int(10) VALUE;
END-PR;
DCL-PR write int(10) EXTPROC('write');
fileds int(10) VALUE;
buffer pointer VALUE;
noofbytes uns(10) VALUE;
END-PR;
DCL-PR open int(10) EXTPROC('open');
ifspath pointer VALUE options(*string);
oflag int(10) VALUE;
mode uns(10) VALUE options(*nopass);
codepage uns(10) VALUE options(*nopass);
END-PR;
// * <-----oflag---->
DCL-C O_readonly 1;
DCL-C O_writeonly 2;
DCL-C O_readwrite 4;
DCL-C O_createfileifnotexist 8;
DCL-C O_exclusivecreate 16;
DCL-C O_truncateto0bytes 64;
DCL-C O_appendtofile 256;
DCL-C O_converttextbycodepage 8388608;
DCL-C O_openintextmode 16777216;
// * <-----mode---->
// * owner,group,other (RWX)
// * owner authority
DCL-C M_readowner 256;
DCL-C M_writeowner 128;
DCL-C M_executeowner 64;
// * group authority
DCL-C M_readgroup 32;
DCL-C M_writegroup 16;
DCL-C M_executegroup 8;
// * other people
DCL-C M_readother 4;
DCL-C M_writeother 2;
DCL-C M_executeother 1;
DCL-S ifspath CHAR(512);
DCL-S oflag int(10);
DCL-S mode uns(10);
DCL-S codepage uns(10);
DCL-S filedescriptor int(10);
DCL-S ifsdata char(500) inz;
DCL-S return_write int(10) inz;
DCL-S return_close int(10) inz;
ifspath = '/home/easyclass/append';
oflag = O_writeonly +
O_createfileifnotexist +
O_appendtofile ;
mode =
M_readowner +
M_writeowner +
M_executeowner;
filedescriptor = open(%trim(ifspath):
oflag:
mode);
if filedescriptor < 0;
return;
endif;
ifsdata = 'DATA APPEND';
return_write = write(filedescriptor:%addr(ifsdata):%size(ifsdata));
if return_write < %size(ifsdata);
return;
endif;
ifsdata = 'CONTINUED';
return_write = write(filedescriptor:%addr(ifsdata):%size(ifsdata));
if return_write < %size(ifsdata);
return;
endif;
return_close = close(filedescriptor);
if return_close = -1;
return;
endif;
*inlr = *on;
return;
Explanation of the above code
ifspath = '/home/easyclass/append';
oflag = O_writeonly +
O_createfileifnotexist +
O_appendtofile ;
mode =
M_readowner +
M_writeowner +
M_executeowner;
filedescriptor = open(%trim(ifspath):
oflag:
mode);
if filedescriptor < 0;
return;
endif;
Here, at first we will create the ifs stream file if not exist and open it in write only mode and will append the data to the file during write instead of replacing the existing content in the ifs stream file. Therefore we pass O_writeonly + O_createfileifnotexist + O_appendtofile ; flags to the openflag second parameter of the open() api. Other parameters being passed are ifspath for the file named "append" on the user home directory and mode parameter i.e. authority for the file to the owner as read, write and execute. If the filedescriptor returned by the open() api is less than zero then api either fails tocreate or open the stream file with specified flags and we return from the program here since file is not opened therefore, no sense of proceeding forward.
ifsdata = 'DATA APPEND';
return_write = write(filedescriptor:%addr(ifsdata):%size(ifsdata));
if return_write < %size(ifsdata);
return;
endif;
ifsdata = 'CONTINUED';
return_write = write(filedescriptor:%addr(ifsdata):%size(ifsdata));
if return_write < %size(ifsdata);
return;
endif;
Here, at next step after opening the file successfully, we will append the data to the ifs stream file using the write() api by passing file descriptor being returned by the open() api and address and size of the ifsdata variable to be written to the disk. If return value by write() api is less than the size of the ifsdata variable then that means all the data is not appended to the ifs stream file therefore, return from the program at this point otherwise proceed further and append the data again to the stream file.
return_close = close(filedescriptor);
if return_close = -1;
return;
endif;
*inlr = *on;
return;
Finally close the file by using close() api and passing file descriptor returned by the open() api. If return value of close() api is -1 then return abnormally otherwise end program normally by first setting last record indicator to ON and return from the program.
Output of the above program
The file already exist and having already some data
Browse : /home/EASYCLASS/append
Record : 1 of 1 by 18 Column : 1 59 by 131
Control :
....+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8....+...
************Beginning of data**************
DATA APPENDCONTINUED
************End of Data********************
Let's call the program again (use option 14 to create the program) to append the data to the ifs stream file.
Browse : /home/EASYCLASS/append
Record : 1 of 1 by 18 Column : 1 59 by 131
Control :
....+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8....+...
************Beginning of data**************
DATA APPENDCONTINUED DATA APPENDCONTINUED
************End of Data********************