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| How to retrieve stream file stat Information using C stat API in RPGLE |
What is stat() API?
The stat() function gets information about a stream file in the IFS such as file size, access permissions, and the time it was last modified etc.
Prototype for the stat() API in C Language
int stat(const char *path, struct stat *buf);
- The stat() function gets status information about a specified file.
- The return value is an int (integer) and values are 0 which indicate success, or -1 if an error occurred.
- const char *path:First parameter is input path. A pointer to the null-terminated path name of the object from which information is required.
- struct stat *buf:Second parameter is output buf. A pointer to the stat data structure. For this parameter we need to create a data structure same as stat data structure in C.
Prototype for the stat() API in RPG
D stat PR 10I 0 ExtProc('stat')
D ifspath * value options(*string)
D statds * value
Layout of the stat data structure in C Language
struct stat {
mode_t st_mode; // File mode
ino_t st_ino; // File serial number
nlink_t st_nlink; // Number of links
uid_t st_uid; // User ID of the owner of file
gid_t st_gid; // Group ID of the group of file
off_t st_size; // For regular files, the file (size in bytes)
time_t st_atime; // Time of last access
time_t st_mtime; // Time of last data modification
time_t st_ctime; // Time of last file status change
dev_t st_dev; // ID of device containing file
size_t st_blksize; // Size of a block of the file
unsigned long st_allocsize; // Allocation size of the file
qp0l_objtype_t st_objtype; // AS/400 object type
unsigned short st_codepage; // Object data codepage
char st_reserved1[62]; // Reserved
unsigned int st_ino_gen_id // file serial number generation id
};
Above defined is the structure definition of stat data structure in C language. You can refer more about stat data structure layout from the IBM documentation.
Layout of the stat data structure in RPG
D statds DS
D filemode 10U 0
D fileid 10U 0
D Numoflinks 5U 0
D reserved2 5U 0
D useridofowner 2A
D grpidofgroup 10U 0
D regularfiles 10U 0
D size 10I 0
D time_access 10I 0
D time_change 10I 0
D time_stschang 10I 0
D filesysid 10U 0
D blocksize 10U 0
D allocatedsize 10U 0
D objecttype 12A
D codepage 5U 0
D ccsid 5U 0
D reserved1 62A
D generationid 10U 0
RPGLE program for retrieve stream file stat
RPG Code in Fixed format to retrieve stream file stat Information using C stat() API in RPGLE.
HDFTACTGRP(*NO)
D stat PR 10I 0 ExtProc('stat')
D ifspath * value options(*string)
D statds * value
D errorifs PR * ExtProc('__errno')
D strerror PR * ExtProc('strerror')
D error_num 10I 0 value
*
Difspath s 512a
Dreturn_stat s 10i 0 inz
Derror_ptr S *
Derror_num S 10I 0 based(error_ptr)
Derrormsg_ptr S *
Derror_msg S 500a based(errormsg_ptr)
D statds DS
D filemode 10U 0
D fileid 10U 0
D Numoflinks 5U 0
D reserved2 5U 0
D useridofowner 2A
D grpidofgroup 10U 0
D regularfiles 10U 0
D size 10I 0
D time_access 10I 0
D time_change 10I 0
D time_stschang 10I 0
D filesysid 10U 0
D blocksize 10U 0
D allocatedsize 10U 0
D objecttype 12A
D codepage 5U 0
D ccsid 5U 0
D reserved1 62A
D generationid 10U 0
C EVAL ifspath = '/home/easyclass/helloworld'
C EVAL return_stat = stat(%trim(ifspath):
C %addr(statds))
C IF return_stat < 0
C EVAL error_ptr = errorIFS()
C EVAL errormsg_ptr = strerror(error_num)
C ENDIF
C EVAL *inlr = *ON
C RETURN
RPG Code in /Free and /End-Free format to retrieve stream file stat Information using C stat() API in RPGLE.
HDFTACTGRP(*NO)
D stat PR 10I 0 ExtProc('stat')
D ifspath * value options(*string)
D statds * value
D errorifs PR * ExtProc('__errno')
D strerror PR * ExtProc('strerror')
D error_num 10I 0 value
*
Difspath s 512a
Dreturn_stat s 10i 0 inz
Derror_ptr S *
Derror_num S 10I 0 based(error_ptr)
Derrormsg_ptr S *
Derror_msg S 500a based(errormsg_ptr)
D statds DS
D filemode 10U 0
D fileid 10U 0
D Numoflinks 5U 0
D reserved2 5U 0
D useridofowner 2A
D grpidofgroup 10U 0
D regularfiles 10U 0
D size 10I 0
D time_access 10I 0
D time_change 10I 0
D time_stschang 10I 0
D filesysid 10U 0
D blocksize 10U 0
D allocatedsize 10U 0
D objecttype 12A
D codepage 5U 0
D ccsid 5U 0
D reserved1 62A
D generationid 10U 0
/free
ifspath = '/home/easyclass/helloworld';
return_stat = stat(%trim(ifspath):
%addr(statds));
if return_stat < 0;
error_ptr = errorIFS();
errormsg_ptr = strerror(error_num);
endif;
*inlr = *on;
return;
/end-free
RPG Code in Fully Free format to retrieve stream file stat Information using C stat() API in RPGLE.
**FREE
CTL-OPT DFTACTGRP(*NO);
DCL-PR stat int(10) EXTPROC('stat');
ifspath pointer VALUE options(*string);
statds pointer VALUE;
END-PR;
DCL-PR errorifs pointer EXTPROC('__errno');
END-PR;
DCL-PR strerror pointer EXTPROC('strerror');
error_num int(10) VALUE;
END-PR;
DCL-S ifspath CHAR(512);
DCL-S return_stat int(10);
DCL-S error_ptr pointer;
DCL-S error_num int(10) based(error_ptr);
DCL-S errormsg_ptr pointer;
DCL-S error_msg char(500) based(errormsg_ptr);
DCL-DS statds;
filemode uns(10);
fileid uns(10);
Numoflinks uns(5);
reserved2 uns(5);
useridofowner char(2);
grpidofgroup uns(10);
regularfiles uns(10);
size int(10);
time_access int(10);
time_change int(10);
time_stschang int(10);
filesysid uns(10);
blocksize uns(10);
allocatedsize uns(10);
objecttype char(12);
codepage uns(5);
ccsid uns(5);
reserved1 char(62);
generationid uns(10);
END-DS;
ifspath = '/home/easyclass/helloworld';
return_stat = stat(%trim(ifspath):
%addr(statds));
if return_stat < 0;
error_ptr = errorIFS();
errormsg_ptr = strerror(error_num);
endif;
*inlr = *on;
return;
Here, in the above source code, we are retrieving the information of the file helloworld in user home directory to the statds data structure by calling stat() C api in RPGLE and returning the integer value. If return is 0 means stat retrieved successfully and if its -1 then failed to retrieve stats and then we call ifs error handling apis to get the error number and corresponding error messages.