Thank you John & Hartmut!
I created a (cute? clever? reckless?) variant on the code posted exploiting the "image file descriptor" which the image activator provides as 4th argument for a main image.
It contains the CHANNEL which the image activator has set set up for the main image, and the full file spec, over and beyond the image name.
Using this, one does NOT have to open the image file again. You can just CRMPSC the whole image. This variant needs to be called pretty much right upon image activation (unless you save argument 4). Consequently I don't think you need to bother with trying to map just the header of the image, as the code will only touch the header parts, and it does a DELTVA after usage to clean up the expreg VA.
My test below uses a COBOL MAIN.
How the get the real image activator argument 4 for a C program, and not the LIB$INITIAL facilitated ARGV vector is left as an excercise for the reader (It's Miller time here!).
Enjoy?
Hein van den Heuvel
HvdH Performance Consulting
$ create ELF_IMGINFO_CRMPSC.C
// File: elf_imginfo_crmpsc.c
// Author: Hein van den Heuvel vandenheuvel@gmail.com
// Creation Date: 05-Mar-2007
// Adapted from elf_imginfo.c by Hartmut Becker 24-Sep-2004
//
// Follow the Elf structure and print some VMS image note entries.
//
// Usage : stat = format_note_section ( image_file_descriptor_address )
// image_file_descriptor_address = argument 4 from main image activation.
// Output : printf to STDOUT. To be adapted to target wished.
//
// Compile with : +sys$library:sys$lib_c.tlb/lib to get ifddef.h !
//
#include
#include
#include
#include
#include
#include
#include
extern sys$asctim(), sys$crmpsc(), sys$deltva() ;
int format_note_section (IFD *ifd) ;
static void decode_note_entries (char *section, int size) ;
static const char magic_plus[] = {
EHDR$K_ELFMAG0, EHDR$K_ELFMAG1, EHDR$K_ELFMAG2, EHDR$K_ELFMAG3,
EHDR$K_ELFCLASS64, EHDR$K_ELFDATA2LSB } ;
int format_note_section (IFD *ifd) {
ELF64_EHDR *ehdr ;
ELF64_SHDR *sh = NULL ;
char *section = NULL ;
char *name ;
int i, stat, return_stat, inadr[2] ;
name = (char *) ifd + ifd->ifd$w_filnamoff ;
i = *name++; // grab length and bump pointer
printf ("File Spec: %*s\n", i, name);
inadr[0] = 0 ;
stat = sys$crmpsc ( inadr, inadr, 0, SEC$M_EXPREG, 0, 0, 0,
ifd->ifd$w_chan, 0, 0, 0, 0);
if (!(stat & 1)) {
printf ("-e-crmpsc, could not map image header\n") ;
return 0;
}
ehdr = (void *) inadr[0] ;
if (0!=strncmp((char*) &ehdr->ehdr$t_e_ident, magic_plus, sizeof magic_plus-1)) {
printf ("-e-dunno, don't understand this file format\n") ;
return 0 ;
}
sh = (ELF64_SHDR*) ((char *) ehdr + ehdr->ehdr$q_e_shoff) ;
for (i=1; i < ehdr->ehdr$w_e_shnum; i++)
if (sh[i].shdr$l_sh_type==SHDR$K_SHT_NOTE) {
section = (char *) ((char *) ehdr + sh[i].shdr$q_sh_offset) ;
decode_note_entries (section, sh[i].shdr$q_sh_size) ;
break ;
}
return_stat = iehdr$w_e_shnum ;
stat = sys$deltva (inadr, 0, 0) ;
if (!(stat & 1)) {
printf ("-e-deltva, could not UNmap image header\n") ;
return 0;
}
return return_stat ;
}
static void decode_note_entries (char *section, int size) {
ELF64_NHDR *nh ;
char *owner;
char *entry;
for (nh = (ELF64_NHDR*)section ; (char*)nh-section nh= (ELF64_NHDR*)((char*)nh+sizeof(ELF64_NHDR)+((nh->nhdr$q_nh_namesz+7)&~7)+((nh->nhdr$q_nh_descsz+7)&~7))) {
if (nh->nhdr$q_nh_namesz>0)
owner = (char*)nh+sizeof(ELF64_NHDR) ;
else owner = "" ;
if (nh->nhdr$q_nh_descsz>0) {
if (nh->nhdr$q_nh_type == NHDR$K_NT_VMS_LINKTIME) {
char timbuf[32] ;
$DESCRIPTOR (timbuf_d, timbuf) ;
short int timlen ;
sys$asctim (&timlen,&timbuf_d,(char*)nh+sizeof(ELF64_NHDR)+((nh->nhdr$q_nh_namesz+7)&~7) ,0) ;
printf ("owner: '%s', linktime: %.*s\n",owner, timlen, timbuf) ;
}
else {
switch (nh->nhdr$q_nh_type) {
case NHDR$K_NT_VMS_IMGNAM:
entry = "imgnam" ;
break ;
case NHDR$K_NT_VMS_IMGID:
entry = "imgid" ;
break ;
case NHDR$K_NT_VMS_GSTNAM:
entry = "gstnam" ;
break ;
case NHDR$K_NT_VMS_IMGBID:
entry = "imgbid" ;
break ;
case NHDR$K_NT_VMS_LINKID:
entry = "linkid" ;
break ;
default:
entry = NULL ;
break ;
}
if (entry)
printf ("owner: '%s', %s: '%s'\n", owner, entry,
(char*)nh+sizeof(ELF64_NHDR) +((nh->nhdr$q_nh_namesz+7)&~7) ) ;
}
}
}
}
$
$
$ create test.cob
IDENTIFICATION DIVISION.
PROGRAM-ID. prn-test IDENT "test:1234".
DATA DIVISION.
WORKING-STORAGE SECTION.
01 link-time-text pic x(24) value spaces.
01 image_file_descriptor_address POINTER.
LINKAGE SECTION.
01 a1 pic s9(11)v9(7) comp.
01 a2 pic s9(11)v9(7) comp.
01 a3 pic s9(11)v9(7) comp.
01 a4 pic s9(11)v9(7) comp.
01 a5 pic s9(11)v9(7) comp.
01 a6 pic s9(11)v9(7) comp.
PROCEDURE DIVISION USING a1,a2,a3,a4,a5,a6.
MY_MAIN SECTION.
MAIN.
SET image_file_descriptor_address TO REFERENCE OF a4.
call "format_note_section" using by value image_file_descriptor_address.
STOP RUN.
$
$ cc ELF_IMGINFO_CRMPSC.C+sys$library:sys$lib_c.tlb/lib
$ link TEST,ELF_IMGINFO_CRMPSC
$ rename TEST.EXE TMP
$ run TMP
$ run TMP/nodeb
File Spec: $9$DKB200:[HEIN]TMP.EXE;1
owner: 'IPF/VMS', imgnam: 'TEST'
owner: 'IPF/VMS', gstnam: 'TEST'
owner: 'IPF/VMS', imgid: 'test:1234'
owner: 'IPF/VMS', linktime: 5-MAR-2007 22:42:05.55
owner: 'IPF/VMS', linkid: 'Linker I02-31'
