forked from ruby/ruby
/
dln.c
1724 lines (1506 loc) · 36.9 KB
/
dln.c
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/************************************************
dln.c -
$Author$
$Date$
created at: Tue Jan 18 17:05:06 JST 1994
Copyright (C) 1993-1999 Yukihiro Matsumoto
************************************************/
#include "config.h"
#include "defines.h"
#include "dln.h"
char *dln_argv0;
#ifdef _AIX
#pragma alloca
#endif
#if defined(HAVE_ALLOCA_H) && !defined(__GNUC__)
#include <alloca.h>
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#else
# include <strings.h>
#endif
#ifndef xmalloc
void *xmalloc();
void *xcalloc();
void *xrealloc();
#endif
#include <stdio.h>
#ifndef NT
# ifndef USE_CWGUSI
# include <sys/file.h>
# endif
#else
#include "missing/file.h"
#endif
#include <sys/types.h>
#include <sys/stat.h>
#ifdef HAVE_SYS_PARAM_H
# include <sys/param.h>
#else
# define MAXPATHLEN 1024
#endif
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifndef NT
char *getenv();
#endif
#ifdef __MACOS__
# include <TextUtils.h>
# include <CodeFragments.h>
# include <Aliases.h>
# include "macruby_private.h"
#endif
#ifdef __BEOS__
# include <image.h>
#endif
int eaccess();
#if defined(HAVE_DLOPEN) && !defined(USE_DLN_A_OUT) && !defined(__CYGWIN32__) && !defined(_AIX)
/* dynamic load with dlopen() */
# define USE_DLN_DLOPEN
#endif
#ifndef FUNCNAME_PATTERN
# if defined(__hp9000s300) || (defined(__NetBSD__) && (!defined(__alpha__) && !defined(__mips__))) || defined(__BORLANDC__) || (defined(__FreeBSD__) && __FreeBSD__ < 3) || defined(__OpenBSD__) || defined(NeXT) || defined(__WATCOMC__) || defined(__APPLE__)
# define FUNCNAME_PATTERN "_Init_%.200s"
# else
# define FUNCNAME_PATTERN "Init_%.200s"
# endif
#endif
static void
init_funcname(buf, file)
char *buf;
char *file;
{
char *p, *slash;
/* Load the file as an object one */
for (p = file, slash = p-1; *p; p++) /* Find position of last '/' */
#ifdef __MACOS__
if (*p == ':') slash = p;
#else
if (*p == '/') slash = p;
#endif
sprintf(buf, FUNCNAME_PATTERN, slash + 1);
for (p = buf; *p; p++) { /* Delete suffix if it exists */
if (*p == '.') {
*p = '\0'; break;
}
}
}
#ifdef USE_DLN_A_OUT
#ifndef LIBC_NAME
# define LIBC_NAME "libc.a"
#endif
#ifndef DLN_DEFAULT_LIB_PATH
# define DLN_DEFAULT_LIB_PATH "/lib:/usr/lib:/usr/local/lib:."
#endif
#include <errno.h>
static int dln_errno;
#define DLN_ENOEXEC ENOEXEC /* Exec format error */
#define DLN_ECONFL 201 /* Symbol name conflict */
#define DLN_ENOINIT 202 /* No inititalizer given */
#define DLN_EUNDEF 203 /* Undefine symbol remains */
#define DLN_ENOTLIB 204 /* Not a library file */
#define DLN_EBADLIB 205 /* Malformed library file */
#define DLN_EINIT 206 /* Not initialized */
static int dln_init_p = 0;
#include "st.h"
#include <ar.h>
#include <a.out.h>
#ifndef N_COMM
# define N_COMM 0x12
#endif
#ifndef N_MAGIC
# define N_MAGIC(x) (x).a_magic
#endif
#define INVALID_OBJECT(h) (N_MAGIC(h) != OMAGIC)
static st_table *sym_tbl;
static st_table *undef_tbl;
static int load_lib();
static int
load_header(fd, hdrp, disp)
int fd;
struct exec *hdrp;
long disp;
{
int size;
lseek(fd, disp, 0);
size = read(fd, hdrp, sizeof(struct exec));
if (size == -1) {
dln_errno = errno;
return -1;
}
if (size != sizeof(struct exec) || N_BADMAG(*hdrp)) {
dln_errno = DLN_ENOEXEC;
return -1;
}
return 0;
}
#if defined(sequent)
#define RELOC_SYMBOL(r) ((r)->r_symbolnum)
#define RELOC_MEMORY_SUB_P(r) ((r)->r_bsr)
#define RELOC_PCREL_P(r) ((r)->r_pcrel || (r)->r_bsr)
#define RELOC_TARGET_SIZE(r) ((r)->r_length)
#endif
/* Default macros */
#ifndef RELOC_ADDRESS
#define RELOC_ADDRESS(r) ((r)->r_address)
#define RELOC_EXTERN_P(r) ((r)->r_extern)
#define RELOC_SYMBOL(r) ((r)->r_symbolnum)
#define RELOC_MEMORY_SUB_P(r) 0
#define RELOC_PCREL_P(r) ((r)->r_pcrel)
#define RELOC_TARGET_SIZE(r) ((r)->r_length)
#endif
#if defined(sun) && defined(sparc)
/* Sparc (Sun 4) macros */
# undef relocation_info
# define relocation_info reloc_info_sparc
# define R_RIGHTSHIFT(r) (reloc_r_rightshift[(r)->r_type])
# define R_BITSIZE(r) (reloc_r_bitsize[(r)->r_type])
# define R_LENGTH(r) (reloc_r_length[(r)->r_type])
static int reloc_r_rightshift[] = {
0, 0, 0, 0, 0, 0, 2, 2, 10, 0, 0, 0, 0, 0, 0,
};
static int reloc_r_bitsize[] = {
8, 16, 32, 8, 16, 32, 30, 22, 22, 22, 13, 10, 32, 32, 16,
};
static int reloc_r_length[] = {
0, 1, 2, 0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
};
# define R_PCREL(r) \
((r)->r_type >= RELOC_DISP8 && (r)->r_type <= RELOC_WDISP22)
# define R_SYMBOL(r) ((r)->r_index)
#endif
#if defined(sequent)
#define R_SYMBOL(r) ((r)->r_symbolnum)
#define R_MEMORY_SUB(r) ((r)->r_bsr)
#define R_PCREL(r) ((r)->r_pcrel || (r)->r_bsr)
#define R_LENGTH(r) ((r)->r_length)
#endif
#ifndef R_SYMBOL
# define R_SYMBOL(r) ((r)->r_symbolnum)
# define R_MEMORY_SUB(r) 0
# define R_PCREL(r) ((r)->r_pcrel)
# define R_LENGTH(r) ((r)->r_length)
#endif
static struct relocation_info *
load_reloc(fd, hdrp, disp)
int fd;
struct exec *hdrp;
long disp;
{
struct relocation_info *reloc;
int size;
lseek(fd, disp + N_TXTOFF(*hdrp) + hdrp->a_text + hdrp->a_data, 0);
size = hdrp->a_trsize + hdrp->a_drsize;
reloc = (struct relocation_info*)xmalloc(size);
if (reloc == NULL) {
dln_errno = errno;
return NULL;
}
if (read(fd, reloc, size) != size) {
dln_errno = errno;
free(reloc);
return NULL;
}
return reloc;
}
static struct nlist *
load_sym(fd, hdrp, disp)
int fd;
struct exec *hdrp;
long disp;
{
struct nlist * buffer;
struct nlist * sym;
struct nlist * end;
long displ;
int size;
lseek(fd, N_SYMOFF(*hdrp) + hdrp->a_syms + disp, 0);
if (read(fd, &size, sizeof(int)) != sizeof(int)) {
goto err_noexec;
}
buffer = (struct nlist*)xmalloc(hdrp->a_syms + size);
if (buffer == NULL) {
dln_errno = errno;
return NULL;
}
lseek(fd, disp + N_SYMOFF(*hdrp), 0);
if (read(fd, buffer, hdrp->a_syms + size) != hdrp->a_syms + size) {
free(buffer);
goto err_noexec;
}
sym = buffer;
end = sym + hdrp->a_syms / sizeof(struct nlist);
displ = (long)buffer + (long)(hdrp->a_syms);
while (sym < end) {
sym->n_un.n_name = (char*)sym->n_un.n_strx + displ;
sym++;
}
return buffer;
err_noexec:
dln_errno = DLN_ENOEXEC;
return NULL;
}
static st_table *
sym_hash(hdrp, syms)
struct exec *hdrp;
struct nlist *syms;
{
st_table *tbl;
struct nlist *sym = syms;
struct nlist *end = syms + (hdrp->a_syms / sizeof(struct nlist));
tbl = st_init_strtable();
if (tbl == NULL) {
dln_errno = errno;
return NULL;
}
while (sym < end) {
st_insert(tbl, sym->n_un.n_name, sym);
sym++;
}
return tbl;
}
static int
dln_init(prog)
const char *prog;
{
char *file;
int fd;
struct exec hdr;
struct nlist *syms;
if (dln_init_p == 1) return 0;
file = dln_find_exe(prog, NULL);
if (file == NULL || (fd = open(file, O_RDONLY)) < 0) {
dln_errno = errno;
return -1;
}
if (load_header(fd, &hdr, 0) == -1) return -1;
syms = load_sym(fd, &hdr, 0);
if (syms == NULL) {
close(fd);
return -1;
}
sym_tbl = sym_hash(&hdr, syms);
if (sym_tbl == NULL) { /* file may be start with #! */
char c = '\0';
char buf[MAXPATHLEN];
char *p;
free(syms);
lseek(fd, 0L, 0);
if (read(fd, &c, 1) == -1) {
dln_errno = errno;
return -1;
}
if (c != '#') goto err_noexec;
if (read(fd, &c, 1) == -1) {
dln_errno = errno;
return -1;
}
if (c != '!') goto err_noexec;
p = buf;
/* skip forwading spaces */
while (read(fd, &c, 1) == 1) {
if (c == '\n') goto err_noexec;
if (c != '\t' && c != ' ') {
*p++ = c;
break;
}
}
/* read in command name */
while (read(fd, p, 1) == 1) {
if (*p == '\n' || *p == '\t' || *p == ' ') break;
p++;
}
*p = '\0';
return dln_init(buf);
}
dln_init_p = 1;
undef_tbl = st_init_strtable();
close(fd);
return 0;
err_noexec:
close(fd);
dln_errno = DLN_ENOEXEC;
return -1;
}
static long
load_text_data(fd, hdrp, bss, disp)
int fd;
struct exec *hdrp;
int bss;
long disp;
{
int size;
unsigned char* addr;
lseek(fd, disp + N_TXTOFF(*hdrp), 0);
size = hdrp->a_text + hdrp->a_data;
if (bss == -1) size += hdrp->a_bss;
else if (bss > 1) size += bss;
addr = (unsigned char*)xmalloc(size);
if (addr == NULL) {
dln_errno = errno;
return 0;
}
if (read(fd, addr, size) != size) {
dln_errno = errno;
free(addr);
return 0;
}
if (bss == -1) {
memset(addr + hdrp->a_text + hdrp->a_data, 0, hdrp->a_bss);
}
else if (bss > 0) {
memset(addr + hdrp->a_text + hdrp->a_data, 0, bss);
}
return (long)addr;
}
static int
undef_print(key, value)
char *key, *value;
{
fprintf(stderr, " %s\n", key);
return ST_CONTINUE;
}
static void
dln_print_undef()
{
fprintf(stderr, " Undefined symbols:\n");
st_foreach(undef_tbl, undef_print, NULL);
}
static void
dln_undefined()
{
if (undef_tbl->num_entries > 0) {
fprintf(stderr, "dln: Calling undefined function\n");
dln_print_undef();
rb_exit(1);
}
}
struct undef {
char *name;
struct relocation_info reloc;
long base;
char *addr;
union {
char c;
short s;
long l;
} u;
};
static st_table *reloc_tbl = NULL;
static void
link_undef(name, base, reloc)
const char *name;
long base;
struct relocation_info *reloc;
{
static int u_no = 0;
struct undef *obj;
char *addr = (char*)(reloc->r_address + base);
obj = (struct undef*)xmalloc(sizeof(struct undef));
obj->name = strdup(name);
obj->reloc = *reloc;
obj->base = base;
switch (R_LENGTH(reloc)) {
case 0: /* byte */
obj->u.c = *addr;
break;
case 1: /* word */
obj->u.s = *(short*)addr;
break;
case 2: /* long */
obj->u.l = *(long*)addr;
break;
}
if (reloc_tbl == NULL) {
reloc_tbl = st_init_numtable();
}
st_insert(reloc_tbl, u_no++, obj);
}
struct reloc_arg {
const char *name;
long value;
};
static int
reloc_undef(no, undef, arg)
int no;
struct undef *undef;
struct reloc_arg *arg;
{
int datum;
char *address;
#if defined(sun) && defined(sparc)
unsigned int mask = 0;
#endif
if (strcmp(arg->name, undef->name) != 0) return ST_CONTINUE;
address = (char*)(undef->base + undef->reloc.r_address);
datum = arg->value;
if (R_PCREL(&(undef->reloc))) datum -= undef->base;
#if defined(sun) && defined(sparc)
datum += undef->reloc.r_addend;
datum >>= R_RIGHTSHIFT(&(undef->reloc));
mask = (1 << R_BITSIZE(&(undef->reloc))) - 1;
mask |= mask -1;
datum &= mask;
switch (R_LENGTH(&(undef->reloc))) {
case 0:
*address = undef->u.c;
*address &= ~mask;
*address |= datum;
break;
case 1:
*(short *)address = undef->u.s;
*(short *)address &= ~mask;
*(short *)address |= datum;
break;
case 2:
*(long *)address = undef->u.l;
*(long *)address &= ~mask;
*(long *)address |= datum;
break;
}
#else
switch (R_LENGTH(&(undef->reloc))) {
case 0: /* byte */
if (R_MEMORY_SUB(&(undef->reloc)))
*address = datum - *address;
else *address = undef->u.c + datum;
break;
case 1: /* word */
if (R_MEMORY_SUB(&(undef->reloc)))
*(short*)address = datum - *(short*)address;
else *(short*)address = undef->u.s + datum;
break;
case 2: /* long */
if (R_MEMORY_SUB(&(undef->reloc)))
*(long*)address = datum - *(long*)address;
else *(long*)address = undef->u.l + datum;
break;
}
#endif
free(undef->name);
free(undef);
return ST_DELETE;
}
static void
unlink_undef(name, value)
const char *name;
long value;
{
struct reloc_arg arg;
arg.name = name;
arg.value = value;
st_foreach(reloc_tbl, reloc_undef, &arg);
}
#ifdef N_INDR
struct indr_data {
char *name0, *name1;
};
static int
reloc_repl(no, undef, data)
int no;
struct undef *undef;
struct indr_data *data;
{
if (strcmp(data->name0, undef->name) == 0) {
free(undef->name);
undef->name = strdup(data->name1);
}
return ST_CONTINUE;
}
#endif
static int
load_1(fd, disp, need_init)
int fd;
long disp;
const char *need_init;
{
static char *libc = LIBC_NAME;
struct exec hdr;
struct relocation_info *reloc = NULL;
long block = 0;
long new_common = 0; /* Length of new common */
struct nlist *syms = NULL;
struct nlist *sym;
struct nlist *end;
int init_p = 0;
char buf[256];
if (load_header(fd, &hdr, disp) == -1) return -1;
if (INVALID_OBJECT(hdr)) {
dln_errno = DLN_ENOEXEC;
return -1;
}
reloc = load_reloc(fd, &hdr, disp);
if (reloc == NULL) return -1;
syms = load_sym(fd, &hdr, disp);
if (syms == NULL) return -1;
sym = syms;
end = syms + (hdr.a_syms / sizeof(struct nlist));
while (sym < end) {
struct nlist *old_sym;
int value = sym->n_value;
#ifdef N_INDR
if (sym->n_type == (N_INDR | N_EXT)) {
char *key = sym->n_un.n_name;
if (st_lookup(sym_tbl, sym[1].n_un.n_name, &old_sym)) {
if (st_delete(undef_tbl, &key, NULL)) {
unlink_undef(key, old_sym->n_value);
free(key);
}
}
else {
struct indr_data data;
data.name0 = sym->n_un.n_name;
data.name1 = sym[1].n_un.n_name;
st_foreach(reloc_tbl, reloc_repl, &data);
st_insert(undef_tbl, strdup(sym[1].n_un.n_name), NULL);
if (st_delete(undef_tbl, &key, NULL)) {
free(key);
}
}
sym += 2;
continue;
}
#endif
if (sym->n_type == (N_UNDF | N_EXT)) {
if (st_lookup(sym_tbl, sym->n_un.n_name, &old_sym) == 0) {
old_sym = NULL;
}
if (value) {
if (old_sym) {
sym->n_type = N_EXT | N_COMM;
sym->n_value = old_sym->n_value;
}
else {
int rnd =
value >= sizeof(double) ? sizeof(double) - 1
: value >= sizeof(long) ? sizeof(long) - 1
: sizeof(short) - 1;
sym->n_type = N_COMM;
new_common += rnd;
new_common &= ~(long)rnd;
sym->n_value = new_common;
new_common += value;
}
}
else {
if (old_sym) {
sym->n_type = N_EXT | N_COMM;
sym->n_value = old_sym->n_value;
}
else {
sym->n_value = (long)dln_undefined;
st_insert(undef_tbl, strdup(sym->n_un.n_name), NULL);
}
}
}
sym++;
}
block = load_text_data(fd, &hdr, hdr.a_bss + new_common, disp);
if (block == 0) goto err_exit;
sym = syms;
while (sym < end) {
struct nlist *new_sym;
char *key;
switch (sym->n_type) {
case N_COMM:
sym->n_value += hdr.a_text + hdr.a_data;
case N_TEXT|N_EXT:
case N_DATA|N_EXT:
sym->n_value += block;
if (st_lookup(sym_tbl, sym->n_un.n_name, &new_sym) != 0
&& new_sym->n_value != (long)dln_undefined) {
dln_errno = DLN_ECONFL;
goto err_exit;
}
key = sym->n_un.n_name;
if (st_delete(undef_tbl, &key, NULL) != 0) {
unlink_undef(key, sym->n_value);
free(key);
}
new_sym = (struct nlist*)xmalloc(sizeof(struct nlist));
*new_sym = *sym;
new_sym->n_un.n_name = strdup(sym->n_un.n_name);
st_insert(sym_tbl, new_sym->n_un.n_name, new_sym);
break;
case N_TEXT:
case N_DATA:
sym->n_value += block;
break;
}
sym++;
}
/*
* First comes the text-relocation
*/
{
struct relocation_info * rel = reloc;
struct relocation_info * rel_beg = reloc +
(hdr.a_trsize/sizeof(struct relocation_info));
struct relocation_info * rel_end = reloc +
(hdr.a_trsize+hdr.a_drsize)/sizeof(struct relocation_info);
while (rel < rel_end) {
char *address = (char*)(rel->r_address + block);
long datum = 0;
#if defined(sun) && defined(sparc)
unsigned int mask = 0;
#endif
if(rel >= rel_beg)
address += hdr.a_text;
if (rel->r_extern) { /* Look it up in symbol-table */
sym = &(syms[R_SYMBOL(rel)]);
switch (sym->n_type) {
case N_EXT|N_UNDF:
link_undef(sym->n_un.n_name, block, rel);
case N_EXT|N_COMM:
case N_COMM:
datum = sym->n_value;
break;
default:
goto err_exit;
}
} /* end.. look it up */
else { /* is static */
switch (R_SYMBOL(rel)) {
case N_TEXT:
case N_DATA:
datum = block;
break;
case N_BSS:
datum = block + new_common;
break;
case N_ABS:
break;
}
} /* end .. is static */
if (R_PCREL(rel)) datum -= block;
#if defined(sun) && defined(sparc)
datum += rel->r_addend;
datum >>= R_RIGHTSHIFT(rel);
mask = (1 << R_BITSIZE(rel)) - 1;
mask |= mask -1;
datum &= mask;
switch (R_LENGTH(rel)) {
case 0:
*address &= ~mask;
*address |= datum;
break;
case 1:
*(short *)address &= ~mask;
*(short *)address |= datum;
break;
case 2:
*(long *)address &= ~mask;
*(long *)address |= datum;
break;
}
#else
switch (R_LENGTH(rel)) {
case 0: /* byte */
if (datum < -128 || datum > 127) goto err_exit;
*address += datum;
break;
case 1: /* word */
*(short *)address += datum;
break;
case 2: /* long */
*(long *)address += datum;
break;
}
#endif
rel++;
}
}
if (need_init) {
int len;
char **libs_to_be_linked = 0;
if (undef_tbl->num_entries > 0) {
if (load_lib(libc) == -1) goto err_exit;
}
init_funcname(buf, need_init);
len = strlen(buf);
for (sym = syms; sym<end; sym++) {
char *name = sym->n_un.n_name;
if (name[0] == '_' && sym->n_value >= block) {
if (strcmp(name+1, "dln_libs_to_be_linked") == 0) {
libs_to_be_linked = (char**)sym->n_value;
}
else if (strcmp(name+1, buf) == 0) {
init_p = 1;
((int (*)())sym->n_value)();
}
}
}
if (libs_to_be_linked && undef_tbl->num_entries > 0) {
while (*libs_to_be_linked) {
load_lib(*libs_to_be_linked);
libs_to_be_linked++;
}
}
}
free(reloc);
free(syms);
if (need_init) {
if (init_p == 0) {
dln_errno = DLN_ENOINIT;
return -1;
}
if (undef_tbl->num_entries > 0) {
if (load_lib(libc) == -1) goto err_exit;
if (undef_tbl->num_entries > 0) {
dln_errno = DLN_EUNDEF;
return -1;
}
}
}
return 0;
err_exit:
if (syms) free(syms);
if (reloc) free(reloc);
if (block) free((char*)block);
return -1;
}
static int target_offset;
static int
search_undef(key, value, lib_tbl)
const char *key;
int value;
st_table *lib_tbl;
{
int offset;
if (st_lookup(lib_tbl, key, &offset) == 0) return ST_CONTINUE;
target_offset = offset;
return ST_STOP;
}
struct symdef {
int rb_str_index;
int lib_offset;
};
char *dln_librrb_ary_path = DLN_DEFAULT_LIB_PATH;
static int
load_lib(lib)
const char *lib;
{
char *path, *file;
char armagic[SARMAG];
int fd, size;
struct ar_hdr ahdr;
st_table *lib_tbl = NULL;
int *data, nsym;
struct symdef *base;
char *name_base;
if (dln_init_p == 0) {
dln_errno = DLN_ENOINIT;
return -1;
}
if (undef_tbl->num_entries == 0) return 0;
dln_errno = DLN_EBADLIB;
if (lib[0] == '-' && lib[1] == 'l') {
char *p = alloca(strlen(lib) + 4);
sprintf(p, "lib%s.a", lib+2);
lib = p;
}
/* library search path: */
/* look for environment variable DLN_LIBRARY_PATH first. */
/* then variable dln_librrb_ary_path. */
/* if path is still NULL, use "." for path. */
path = getenv("DLN_LIBRARY_PATH");
if (path == NULL) path = dln_librrb_ary_path;
file = dln_find_file(lib, path);
fd = open(file, O_RDONLY);
if (fd == -1) goto syserr;
size = read(fd, armagic, SARMAG);
if (size == -1) goto syserr;
if (size != SARMAG) {
dln_errno = DLN_ENOTLIB;
goto badlib;
}
size = read(fd, &ahdr, sizeof(ahdr));
if (size == -1) goto syserr;
if (size != sizeof(ahdr) || sscanf(ahdr.ar_size, "%d", &size) != 1) {
goto badlib;
}
if (strncmp(ahdr.ar_name, "__.SYMDEF", 9) == 0) {
/* make hash table from __.SYMDEF */
lib_tbl = st_init_strtable();
data = (int*)xmalloc(size);
if (data == NULL) goto syserr;
size = read(fd, data, size);
nsym = *data / sizeof(struct symdef);
base = (struct symdef*)(data + 1);
name_base = (char*)(base + nsym) + sizeof(int);
while (nsym > 0) {
char *name = name_base + base->rb_str_index;
st_insert(lib_tbl, name, base->lib_offset + sizeof(ahdr));
nsym--;
base++;
}
for (;;) {
target_offset = -1;
st_foreach(undef_tbl, search_undef, lib_tbl);
if (target_offset == -1) break;
if (load_1(fd, target_offset, 0) == -1) {
st_free_table(lib_tbl);
free(data);
goto badlib;
}
if (undef_tbl->num_entries == 0) break;
}
free(data);
st_free_table(lib_tbl);
}
else {
/* linear library, need to scan (FUTURE) */
for (;;) {
int offset = SARMAG;
int found = 0;
struct exec hdr;
struct nlist *syms, *sym, *end;
while (undef_tbl->num_entries > 0) {
found = 0;
lseek(fd, offset, 0);
size = read(fd, &ahdr, sizeof(ahdr));
if (size == -1) goto syserr;
if (size == 0) break;
if (size != sizeof(ahdr)
|| sscanf(ahdr.ar_size, "%d", &size) != 1) {
goto badlib;
}
offset += sizeof(ahdr);
if (load_header(fd, &hdr, offset) == -1)
goto badlib;
syms = load_sym(fd, &hdr, offset);