freebsd-dev/contrib/file/readelf.c
2000-11-26 21:26:20 +00:00

516 lines
12 KiB
C

#include "file.h"
#ifdef BUILTIN_ELF
#include <sys/types.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <errno.h>
#include "readelf.h"
#ifndef lint
FILE_RCSID("@(#)$Id: readelf.c,v 1.17 2000/08/05 19:00:12 christos Exp $")
#endif
#ifdef ELFCORE
static void dophn_core __P((int, int, int, off_t, int, size_t));
#endif
static void dophn_exec __P((int, int, int, off_t, int, size_t));
static void doshn __P((int, int, int, off_t, int, size_t));
static uint16_t getu16 __P((int, int));
static uint32_t getu32 __P((int, uint32_t));
static uint64_t getu64 __P((int, uint64_t));
static uint16_t
getu16(swap, value)
int swap;
uint16_t value;
{
union {
uint16_t ui;
char c[2];
} retval, tmpval;
if (swap) {
tmpval.ui = value;
retval.c[0] = tmpval.c[1];
retval.c[1] = tmpval.c[0];
return retval.ui;
} else
return value;
}
static uint32_t
getu32(swap, value)
int swap;
uint32_t value;
{
union {
uint32_t ui;
char c[4];
} retval, tmpval;
if (swap) {
tmpval.ui = value;
retval.c[0] = tmpval.c[3];
retval.c[1] = tmpval.c[2];
retval.c[2] = tmpval.c[1];
retval.c[3] = tmpval.c[0];
return retval.ui;
} else
return value;
}
static uint64_t
getu64(swap, value)
int swap;
uint64_t value;
{
union {
uint64_t ui;
char c[8];
} retval, tmpval;
if (swap) {
tmpval.ui = value;
retval.c[0] = tmpval.c[7];
retval.c[1] = tmpval.c[6];
retval.c[2] = tmpval.c[5];
retval.c[3] = tmpval.c[4];
retval.c[4] = tmpval.c[3];
retval.c[5] = tmpval.c[2];
retval.c[6] = tmpval.c[1];
retval.c[7] = tmpval.c[0];
return retval.ui;
} else
return value;
}
#define sh_addr (class == ELFCLASS32 \
? (void *) &sh32 \
: (void *) &sh64)
#define shs_type (class == ELFCLASS32 \
? getu32(swap, sh32.sh_type) \
: getu32(swap, sh64.sh_type))
#define ph_addr (class == ELFCLASS32 \
? (void *) &ph32 \
: (void *) &ph64)
#define ph_type (class == ELFCLASS32 \
? getu32(swap, ph32.p_type) \
: getu32(swap, ph64.p_type))
#define ph_offset (class == ELFCLASS32 \
? getu32(swap, ph32.p_offset) \
: getu64(swap, ph64.p_offset))
#define nh_size (class == ELFCLASS32 \
? sizeof *nh32 \
: sizeof *nh64)
#define nh_type (class == ELFCLASS32 \
? getu32(swap, nh32->n_type) \
: getu32(swap, nh64->n_type))
#define nh_namesz (class == ELFCLASS32 \
? getu32(swap, nh32->n_namesz) \
: getu32(swap, nh64->n_namesz))
#define nh_descsz (class == ELFCLASS32 \
? getu32(swap, nh32->n_descsz) \
: getu32(swap, nh64->n_descsz))
#define prpsoffsets(i) (class == ELFCLASS32 \
? prpsoffsets32[i] \
: prpsoffsets64[i])
static void
doshn(class, swap, fd, off, num, size)
int class;
int swap;
int fd;
off_t off;
int num;
size_t size;
{
Elf32_Shdr sh32;
Elf64_Shdr sh64;
if (lseek(fd, off, SEEK_SET) == -1)
error("lseek failed (%s).\n", strerror(errno));
for ( ; num; num--) {
if (read(fd, sh_addr, size) == -1)
error("read failed (%s).\n", strerror(errno));
if (shs_type == SHT_SYMTAB /* || shs_type == SHT_DYNSYM */) {
(void) printf (", not stripped");
return;
}
}
(void) printf (", stripped");
}
/*
* Look through the program headers of an executable image, searching
* for a PT_INTERP section; if one is found, it's dynamically linked,
* otherwise it's statically linked.
*/
static void
dophn_exec(class, swap, fd, off, num, size)
int class;
int swap;
int fd;
off_t off;
int num;
size_t size;
{
Elf32_Phdr ph32;
Elf64_Phdr ph64;
char *linking_style = "statically";
char *shared_libraries = "";
if (lseek(fd, off, SEEK_SET) == -1)
error("lseek failed (%s).\n", strerror(errno));
for ( ; num; num--) {
if (read(fd, ph_addr, size) == -1)
error("read failed (%s).\n", strerror(errno));
switch (ph_type) {
case PT_DYNAMIC:
linking_style = "dynamically";
break;
case PT_INTERP:
shared_libraries = " (uses shared libs)";
break;
}
}
printf(", %s linked%s", linking_style, shared_libraries);
}
#ifdef ELFCORE
size_t prpsoffsets32[] = {
8, /* FreeBSD */
28, /* Linux 2.0.36 */
32, /* Linux (I forget which kernel version) */
84, /* SunOS 5.x */
};
size_t prpsoffsets64[] = {
120, /* SunOS 5.x, 64-bit */
};
#define NOFFSETS32 (sizeof prpsoffsets32 / sizeof prpsoffsets32[0])
#define NOFFSETS64 (sizeof prpsoffsets64 / sizeof prpsoffsets64[0])
#define NOFFSETS (class == ELFCLASS32 ? NOFFSETS32 : NOFFSETS64)
/*
* Look through the program headers of an executable image, searching
* for a PT_NOTE section of type NT_PRPSINFO, with a name "CORE" or
* "FreeBSD"; if one is found, try looking in various places in its
* contents for a 16-character string containing only printable
* characters - if found, that string should be the name of the program
* that dropped core. Note: right after that 16-character string is,
* at least in SunOS 5.x (and possibly other SVR4-flavored systems) and
* Linux, a longer string (80 characters, in 5.x, probably other
* SVR4-flavored systems, and Linux) containing the start of the
* command line for that program.
*
* The signal number probably appears in a section of type NT_PRSTATUS,
* but that's also rather OS-dependent, in ways that are harder to
* dissect with heuristics, so I'm not bothering with the signal number.
* (I suppose the signal number could be of interest in situations where
* you don't have the binary of the program that dropped core; if you
* *do* have that binary, the debugger will probably tell you what
* signal it was.)
*/
static void
dophn_core(class, swap, fd, off, num, size)
int class;
int swap;
int fd;
off_t off;
int num;
size_t size;
{
Elf32_Phdr ph32;
Elf32_Nhdr *nh32;
Elf64_Phdr ph64;
Elf64_Nhdr *nh64;
size_t offset, nameoffset, noffset, reloffset;
unsigned char c;
int i, j;
char nbuf[BUFSIZ];
int bufsize;
int is_freebsd;
/*
* Loop through all the program headers.
*/
for ( ; num; num--) {
if (lseek(fd, off, SEEK_SET) == -1)
error("lseek failed (%s).\n", strerror(errno));
if (read(fd, ph_addr, size) == -1)
error("read failed (%s).\n", strerror(errno));
off += size;
if (ph_type != PT_NOTE)
continue;
/*
* This is a PT_NOTE section; loop through all the notes
* in the section.
*/
if (lseek(fd, (off_t) ph_offset, SEEK_SET) == -1)
error("lseek failed (%s).\n", strerror(errno));
bufsize = read(fd, nbuf, BUFSIZ);
if (bufsize == -1)
error(": " "read failed (%s).\n", strerror(errno));
offset = 0;
for (;;) {
if (offset >= bufsize)
break;
if (class == ELFCLASS32)
nh32 = (Elf32_Nhdr *)&nbuf[offset];
else
nh64 = (Elf64_Nhdr *)&nbuf[offset];
offset += nh_size;
/*
* Check whether this note has the name "CORE" or
* "FreeBSD".
*/
if (offset + nh_namesz >= bufsize) {
/*
* We're past the end of the buffer.
*/
break;
}
nameoffset = offset;
offset += nh_namesz;
offset = ((offset + 3)/4)*4;
/*
* Sigh. The 2.0.36 kernel in Debian 2.1, at
* least, doesn't correctly implement name
* sections, in core dumps, as specified by
* the "Program Linking" section of "UNIX(R) System
* V Release 4 Programmer's Guide: ANSI C and
* Programming Support Tools", because my copy
* clearly says "The first 'namesz' bytes in 'name'
* contain a *null-terminated* [emphasis mine]
* character representation of the entry's owner
* or originator", but the 2.0.36 kernel code
* doesn't include the terminating null in the
* name....
*/
if ((nh_namesz == 4 &&
strncmp(&nbuf[nameoffset], "CORE", 4) == 0) ||
(nh_namesz == 5 &&
strcmp(&nbuf[nameoffset], "CORE") == 0))
is_freebsd = 0;
else if ((nh_namesz == 8 &&
strcmp(&nbuf[nameoffset], "FreeBSD") == 0))
is_freebsd = 1;
else
continue;
if (nh_type == NT_PRPSINFO) {
/*
* Extract the program name. We assume
* it to be 16 characters (that's what it
* is in SunOS 5.x and Linux).
*
* Unfortunately, it's at a different offset
* in varous OSes, so try multiple offsets.
* If the characters aren't all printable,
* reject it.
*/
for (i = 0; i < NOFFSETS; i++) {
reloffset = prpsoffsets(i);
noffset = offset + reloffset;
for (j = 0; j < 16;
j++, noffset++, reloffset++) {
/*
* Make sure we're not past
* the end of the buffer; if
* we are, just give up.
*/
if (noffset >= bufsize)
goto tryanother;
/*
* Make sure we're not past
* the end of the contents;
* if we are, this obviously
* isn't the right offset.
*/
if (reloffset >= nh_descsz)
goto tryanother;
c = nbuf[noffset];
if (c == '\0') {
/*
* A '\0' at the
* beginning is
* obviously wrong.
* Any other '\0'
* means we're done.
*/
if (j == 0)
goto tryanother;
else
break;
} else {
/*
* A nonprintable
* character is also
* wrong.
*/
#define isquote(c) (strchr("'\"`", (c)) != NULL)
if (!isprint(c) ||
isquote(c))
goto tryanother;
}
}
/*
* Well, that worked.
*/
printf(", from '%.16s'",
&nbuf[offset + prpsoffsets(i)]);
break;
tryanother:
;
}
break;
}
offset += nh_descsz;
offset = ((offset + 3)/4)*4;
}
}
}
#endif
void
tryelf(fd, buf, nbytes)
int fd;
unsigned char *buf;
int nbytes;
{
union {
int32 l;
char c[sizeof (int32)];
} u;
int class;
int swap;
/*
* ELF executables have multiple section headers in arbitrary
* file locations and thus file(1) cannot determine it from easily.
* Instead we traverse thru all section headers until a symbol table
* one is found or else the binary is stripped.
*/
if (buf[EI_MAG0] != ELFMAG0
|| (buf[EI_MAG1] != ELFMAG1 && buf[EI_MAG1] != OLFMAG1)
|| buf[EI_MAG2] != ELFMAG2 || buf[EI_MAG3] != ELFMAG3)
return;
class = buf[4];
if (class == ELFCLASS32) {
Elf32_Ehdr elfhdr;
if (nbytes <= sizeof (Elf32_Ehdr))
return;
u.l = 1;
(void) memcpy(&elfhdr, buf, sizeof elfhdr);
swap = (u.c[sizeof(int32) - 1] + 1) != elfhdr.e_ident[5];
if (getu16(swap, elfhdr.e_type) == ET_CORE)
#ifdef ELFCORE
dophn_core(class, swap,
fd,
getu32(swap, elfhdr.e_phoff),
getu16(swap, elfhdr.e_phnum),
getu16(swap, elfhdr.e_phentsize));
#else
;
#endif
else {
if (getu16(swap, elfhdr.e_type) == ET_EXEC) {
dophn_exec(class, swap,
fd,
getu32(swap, elfhdr.e_phoff),
getu16(swap, elfhdr.e_phnum),
getu16(swap, elfhdr.e_phentsize));
}
doshn(class, swap,
fd,
getu32(swap, elfhdr.e_shoff),
getu16(swap, elfhdr.e_shnum),
getu16(swap, elfhdr.e_shentsize));
}
return;
}
if (class == ELFCLASS64) {
Elf64_Ehdr elfhdr;
if (nbytes <= sizeof (Elf64_Ehdr))
return;
u.l = 1;
(void) memcpy(&elfhdr, buf, sizeof elfhdr);
swap = (u.c[sizeof(int32) - 1] + 1) != elfhdr.e_ident[5];
if (getu16(swap, elfhdr.e_type) == ET_CORE)
#ifdef ELFCORE
dophn_core(class, swap,
fd,
#ifdef USE_ARRAY_FOR_64BIT_TYPES
getu32(swap, elfhdr.e_phoff[1]),
#else
getu64(swap, elfhdr.e_phoff),
#endif
getu16(swap, elfhdr.e_phnum),
getu16(swap, elfhdr.e_phentsize));
#else
;
#endif
else
{
if (getu16(swap, elfhdr.e_type) == ET_EXEC) {
dophn_exec(class, swap,
fd,
#ifdef USE_ARRAY_FOR_64BIT_TYPES
getu32(swap, elfhdr.e_phoff[1]),
#else
getu64(swap, elfhdr.e_phoff),
#endif
getu16(swap, elfhdr.e_phnum),
getu16(swap, elfhdr.e_phentsize));
}
doshn(class, swap,
fd,
#ifdef USE_ARRAY_FOR_64BIT_TYPES
getu32(swap, elfhdr.e_shoff[1]),
#else
getu64(swap, elfhdr.e_shoff),
#endif
getu16(swap, elfhdr.e_shnum),
getu16(swap, elfhdr.e_shentsize));
}
return;
}
}
#endif