elf_rawdata failing when using ELF_C_READ

[Martin Storsjö <martin at martin.st>]

Hi,

When using libelf from elfutils 0.143, the elf_rawdata function fails (and 
elf_errmsg says "out of memory") when trying to get raw data using these 
function calls:

int fd = open(elfinput, O_RDONLY);
Elf* elf = elf_begin(fd, ELF_C_READ, NULL);
size_t filesize = 0;
const char* rawdata = elf_rawfile(elf, &filesize);

(The full uncut example reproducing this bug is attached.)

As far as I can tell, this is due to elf->maximum_size being ~0 when this 
call is made. If I change the flags given to elf_begin to ELF_C_READ_MMAP, 
this works fine.

The same example above works just fine when using libelf by Michael 
Riepe.


Is this a bug, or are there any prerequisites for calling elf_rawfile?

Kind regards,
// Martin Storsjö

#define _LARGEFILE64_SOURCE
#include <sys/types.h>
#include <libelf.h>

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>

int main(int argc, char *argv[]) {
	const char* elfinput;
	int fd;
	Elf* elf;
	size_t filesize;
	const char* rawdata;

	if (elf_version(EV_CURRENT) == EV_NONE) {
		fprintf(stderr, "Elf library out of date\n");
		return 1;
	}

	if (argc < 2) {
		fprintf(stderr, "%s elffile\n", argv[0]);
		return 1;
	}
	elfinput = argv[1];

	fd = open(elfinput, O_RDONLY);
	if (fd < 0) {
		perror(elfinput);
		return 1;
	}

	elf = elf_begin(fd, ELF_C_READ, NULL);
	if (!elf) {
		fprintf(stderr, "%s\n", elf_errmsg(elf_errno()));
		close(fd);
		return 1;
	}

	filesize = 0;
	rawdata = elf_rawfile(elf, &filesize);
	if (!rawdata) {
		fprintf(stderr, "elf_rawfile failed: %s\n", elf_errmsg(elf_errno()));
		return 1;
	}
	printf("rawdata: %p size: %d\n", rawdata, filesize);
	elf_end(elf);
	close(fd);
	return 0;
}