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elfdump: Add -E to test if a file is an ELF binary.

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This is intended to replace potentially unreliable checks like:

	file -b $1 | grep -q '^ELF ..-bit .SB executable'

Reviewed by:	emaste
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D15971
This commit is contained in:
Brooks Davis 2018-11-05 22:53:50 +00:00
parent 3c03efc4ab
commit c35530f464
2 changed files with 21 additions and 6 deletions
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9
usr.bin/elfdump/elfdump.1
View File

@ -24,7 +24,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd January 15, 2003
.Dd November 5, 2018
.Dt ELFDUMP 1
.Os
.Sh NAME
@ -34,7 +34,7 @@
files
.Sh SYNOPSIS
.Nm
.Fl a | cdeGhinprs
.Fl a | E | cdeGhinprs
.Op Fl w Ar file
.Ar file
.Sh DESCRIPTION
@ -55,6 +55,11 @@ Dump section headers.
Dump dynamic symbols.
.It Fl e
Dump ELF header.
.It Fl E
Return success if
.Ar file
is an ELF file and failure if it is not.
This option is exclusive with other options.
.It Fl G
Dump the GOT.
.It Fl h

18
usr.bin/elfdump/elfdump.c
View File

@ -60,6 +60,7 @@ __FBSDID("$FreeBSD$");
#define ED_SHDR (1<<8)
#define ED_SYMTAB (1<<9)
#define ED_ALL ((1<<10)-1)
#define ED_IS_ELF (1<<10) /* Exclusive with other flags */
#define elf_get_addr elf_get_quad
#define elf_get_off elf_get_quad
@ -518,7 +519,7 @@ main(int ac, char **av)
out = stdout;
flags = 0;
while ((ch = getopt(ac, av, "acdeiGhnprsw:")) != -1)
while ((ch = getopt(ac, av, "acdEeiGhnprsw:")) != -1)
switch (ch) {
case 'a':
flags = ED_ALL;
@ -529,6 +530,9 @@ main(int ac, char **av)
case 'd':
flags |= ED_DYN;
break;
case 'E':
flags = ED_IS_ELF;
break;
case 'e':
flags |= ED_EHDR;
break;
@ -566,7 +570,8 @@ main(int ac, char **av)
}
ac -= optind;
av += optind;
if (ac == 0 || flags == 0)
if (ac == 0 || flags == 0 || ((flags & ED_IS_ELF) &&
(ac != 1 || (flags & ~ED_IS_ELF) || out != stdout)))
usage();
if ((fd = open(*av, O_RDONLY)) < 0 ||
fstat(fd, &sb) < 0)
@ -584,8 +589,12 @@ main(int ac, char **av)
e = mmap(NULL, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);
if (e == MAP_FAILED)
err(1, NULL);
if (!IS_ELF(*(Elf32_Ehdr *)e))
if (!IS_ELF(*(Elf32_Ehdr *)e)) {
if (flags & ED_IS_ELF)
exit(1);
errx(1, "not an elf file");
} else if (flags & ED_IS_ELF)
exit (0);
phoff = elf_get_off(e, e, E_PHOFF);
shoff = elf_get_off(e, e, E_SHOFF);
phentsize = elf_get_quarter(e, e, E_PHENTSIZE);
@ -1254,6 +1263,7 @@ elf_get_quad(Elf32_Ehdr *e, void *base, elf_member_t member)
static void
usage(void)
{
fprintf(stderr, "usage: elfdump -a | -cdeGhinprs [-w file] file\n");
fprintf(stderr,
"usage: elfdump -a | -E | -cdeGhinprs [-w file] file\n");
exit(1);
}