freebsd-dev/gnu/usr.bin/ld/lib.c
Nate Williams 4979433a3c Modify the default behavior of the linker to no longer prefer static
members over shared library members.  This modification causes the linker
to use the first definition it sees for a symbol instead of having
priorities based on the library type.  This modification should allow
gdb to compile again.

Obtained from:
  Email conversation with Paul Kranenbury, but implemented completely by
  me.  If it doesn't work, it's my fault not his.
1995-03-22 19:38:07 +00:00

869 lines
21 KiB
C

/*
* $Id: lib.c,v 1.12 1995/03/04 17:46:08 nate Exp $ - library routines
*/
#include <sys/param.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/time.h>
#include <err.h>
#include <fcntl.h>
#include <ar.h>
#include <ranlib.h>
#include <a.out.h>
#include <stab.h>
#include <string.h>
#include <dirent.h>
#include <ctype.h>
#include "ld.h"
static void linear_library __P((int, struct file_entry *));
static void symdef_library __P((int, struct file_entry *, int));
static struct file_entry *decode_library_subfile __P((int,
struct file_entry *,
int, int *));
/*
* Search the library ENTRY, already open on descriptor FD. This means
* deciding which library members to load, making a chain of `struct
* file_entry' for those members, and entering their global symbols in the
* hash table.
*/
void
search_library(fd, entry)
int fd;
struct file_entry *entry;
{
int member_length;
register char *name;
register struct file_entry *subentry;
if (!(link_mode & FORCEARCHIVE) && !undefined_global_sym_count)
return;
/* Examine its first member, which starts SARMAG bytes in. */
subentry = decode_library_subfile(fd, entry, SARMAG, &member_length);
if (!subentry)
return;
name = subentry->filename;
free(subentry);
/* Search via __.SYMDEF if that exists, else linearly. */
if (!strcmp(name, "__.SYMDEF"))
symdef_library(fd, entry, member_length);
else
linear_library(fd, entry);
}
/*
* Construct and return a file_entry for a library member. The library's
* file_entry is library_entry, and the library is open on FD.
* SUBFILE_OFFSET is the byte index in the library of this member's header.
* We store the length of the member into *LENGTH_LOC.
*/
static struct file_entry *
decode_library_subfile(fd, library_entry, subfile_offset, length_loc)
int fd;
struct file_entry *library_entry;
int subfile_offset;
int *length_loc;
{
int bytes_read;
register int namelen;
int member_length, content_length;
int starting_offset;
register char *name;
struct ar_hdr hdr1;
register struct file_entry *subentry;
lseek(fd, subfile_offset, 0);
bytes_read = read(fd, &hdr1, sizeof hdr1);
if (!bytes_read)
return 0; /* end of archive */
if (sizeof hdr1 != bytes_read)
errx(1, "%s: malformed library archive",
get_file_name(library_entry));
if (sscanf(hdr1.ar_size, "%d", &member_length) != 1)
errx(1, "%s: malformatted header of archive member: %.*s",
get_file_name(library_entry),
sizeof(hdr1.ar_name), hdr1.ar_name);
subentry = (struct file_entry *) xmalloc(sizeof(struct file_entry));
bzero(subentry, sizeof(struct file_entry));
for (namelen = 0;
namelen < sizeof hdr1.ar_name
&& hdr1.ar_name[namelen] != 0 && hdr1.ar_name[namelen] != ' '
&& hdr1.ar_name[namelen] != '/';
namelen++);
starting_offset = subfile_offset + sizeof hdr1;
content_length = member_length;
#ifdef AR_EFMT1
/*
* BSD 4.4 extended AR format: #1/<namelen>, with name as the
* first <namelen> bytes of the file
*/
if (strncmp(hdr1.ar_name, AR_EFMT1, sizeof(AR_EFMT1) - 1) == 0 &&
isdigit(hdr1.ar_name[sizeof(AR_EFMT1) - 1])) {
namelen = atoi(&hdr1.ar_name[sizeof(AR_EFMT1) - 1]);
name = (char *)xmalloc(namelen + 1);
if (read(fd, name, namelen) != namelen)
errx(1, "%s: malformatted archive member: %.*s",
get_file_name(library_entry),
sizeof(hdr1.ar_name), hdr1.ar_name);
name[namelen] = 0;
content_length -= namelen;
starting_offset += namelen;
} else
#endif
{
name = (char *)xmalloc(namelen + 1);
strncpy(name, hdr1.ar_name, namelen);
name[namelen] = 0;
}
subentry->filename = name;
subentry->local_sym_name = name;
subentry->starting_offset = starting_offset;
subentry->superfile = library_entry;
subentry->total_size = content_length;
#if 0
subentry->symbols = 0;
subentry->strings = 0;
subentry->subfiles = 0;
subentry->chain = 0;
subentry->flags = 0;
#endif
(*length_loc) = member_length;
return subentry;
}
static int subfile_wanted_p __P((struct file_entry *));
/*
* Search a library that has a __.SYMDEF member. FD is a descriptor on
* which the library is open. The file pointer is assumed to point at the
* __.SYMDEF data. ENTRY is the library's file_entry. MEMBER_LENGTH is the
* length of the __.SYMDEF data.
*/
static void
symdef_library(fd, entry, member_length)
int fd;
struct file_entry *entry;
int member_length;
{
int *symdef_data = (int *) xmalloc(member_length);
register struct ranlib *symdef_base;
char *sym_name_base;
int nsymdefs;
int length_of_strings;
int not_finished;
int bytes_read;
register int i;
struct file_entry *prev = 0;
int prev_offset = 0;
bytes_read = read(fd, symdef_data, member_length);
if (bytes_read != member_length)
errx(1, "%s: malformatted __.SYMDEF",
get_file_name(entry));
nsymdefs = md_swap_long(*symdef_data) / sizeof(struct ranlib);
if (nsymdefs < 0 ||
nsymdefs * sizeof(struct ranlib) + 2 * sizeof(int) > member_length)
errx(1, "%s: malformatted __.SYMDEF",
get_file_name(entry));
symdef_base = (struct ranlib *) (symdef_data + 1);
length_of_strings = md_swap_long(*(int *) (symdef_base + nsymdefs));
if (length_of_strings < 0
|| nsymdefs * sizeof(struct ranlib) + length_of_strings
+ 2 * sizeof(int) > member_length)
errx(1, "%s: malformatted __.SYMDEF",
get_file_name(entry));
sym_name_base = sizeof(int) + (char *) (symdef_base + nsymdefs);
/* Check all the string indexes for validity. */
md_swapin_ranlib_hdr(symdef_base, nsymdefs);
for (i = 0; i < nsymdefs; i++) {
register int index = symdef_base[i].ran_un.ran_strx;
if (index < 0 || index >= length_of_strings
|| (index && *(sym_name_base + index - 1)))
errx(1, "%s: malformatted __.SYMDEF",
get_file_name(entry));
}
/*
* Search the symdef data for members to load. Do this until one
* whole pass finds nothing to load.
*/
not_finished = 1;
while (not_finished) {
not_finished = 0;
/*
* Scan all the symbols mentioned in the symdef for ones that
* we need. Load the library members that contain such
* symbols.
*/
for (i = 0; (i < nsymdefs &&
((link_mode & FORCEARCHIVE) ||
undefined_global_sym_count ||
common_defined_global_count)); i++) {
register symbol *sp;
int junk;
register int j;
register int offset = symdef_base[i].ran_off;
struct file_entry *subentry;
if (symdef_base[i].ran_un.ran_strx < 0)
continue;
sp = getsym_soft(sym_name_base
+ symdef_base[i].ran_un.ran_strx);
/*
* If we find a symbol that appears to be needed,
* think carefully about the archive member that the
* symbol is in.
*/
/*
* Per Mike Karels' recommendation, we no longer load
* library files if the only reference(s) that would
* be satisfied are 'common' references. This
* prevents some problems with name pollution (e.g. a
* global common 'utime' linked to a function).
*
* If we're not forcing the archive in then we don't
* need to bother if: we've never heard of the symbol,
* or if it is already defined. The last clause causes
* archive members to be searched for definitions
* satisfying undefined shared object symbols.
*/
if (!(link_mode & FORCEARCHIVE) &&
(!sp || sp->defined ||
(!(sp->flags & GS_REFERENCED) &&
!sp->sorefs)))
continue;
/*
* Don't think carefully about any archive member
* more than once in a given pass.
*/
if (prev_offset == offset)
continue;
prev_offset = offset;
/*
* Read the symbol table of the archive member.
*/
subentry = decode_library_subfile(fd,
entry, offset, &junk);
if (subentry == 0)
errx(1,
"invalid offset for %s in symbol table of %s",
sym_name_base
+ symdef_base[i].ran_un.ran_strx,
entry->filename);
read_entry_symbols(fd, subentry);
subentry->strings = (char *)
alloca(subentry->string_size);
read_entry_strings(fd, subentry);
/*
* Now scan the symbol table and decide whether to
* load.
*/
if (!(link_mode & FORCEARCHIVE) &&
!subfile_wanted_p(subentry)) {
if (subentry->symbols)
free(subentry->symbols);
free(subentry);
} else {
/*
* This member is needed; load it. Since we
* are loading something on this pass, we
* must make another pass through the symdef
* data.
*/
not_finished = 1;
read_entry_relocation(fd, subentry);
enter_file_symbols(subentry);
if (prev)
prev->chain = subentry;
else
entry->subfiles = subentry;
prev = subentry;
/*
* Clear out this member's symbols from the
* symdef data so that following passes won't
* waste time on them.
*/
for (j = 0; j < nsymdefs; j++) {
if (symdef_base[j].ran_off == offset)
symdef_base[j].ran_un.ran_strx = -1;
}
/*
* We'll read the strings again
* if we need them.
*/
subentry->strings = 0;
}
}
}
free(symdef_data);
}
/*
* Search a library that has no __.SYMDEF. ENTRY is the library's file_entry.
* FD is the descriptor it is open on.
*/
static void
linear_library(fd, entry)
int fd;
struct file_entry *entry;
{
register struct file_entry *prev = 0;
register int this_subfile_offset = SARMAG;
while ((link_mode & FORCEARCHIVE) ||
undefined_global_sym_count || common_defined_global_count) {
int member_length;
register struct file_entry *subentry;
subentry = decode_library_subfile(fd, entry,
this_subfile_offset, &member_length);
if (!subentry)
return;
read_entry_symbols(fd, subentry);
subentry->strings = (char *)alloca(subentry->string_size);
read_entry_strings(fd, subentry);
if (!(link_mode & FORCEARCHIVE) &&
!subfile_wanted_p(subentry)) {
if (subentry->symbols)
free(subentry->symbols);
free(subentry);
} else {
read_entry_relocation(fd, subentry);
enter_file_symbols(subentry);
if (prev)
prev->chain = subentry;
else
entry->subfiles = subentry;
prev = subentry;
subentry->strings = 0; /* Since space will dissapear
* on return */
}
this_subfile_offset += member_length + sizeof(struct ar_hdr);
if (this_subfile_offset & 1)
this_subfile_offset++;
}
}
/*
* ENTRY is an entry for a library member. Its symbols have been read into
* core, but not entered. Return nonzero if we ought to load this member.
*/
static int
subfile_wanted_p(entry)
struct file_entry *entry;
{
struct localsymbol *lsp, *lspend;
#ifdef DOLLAR_KLUDGE
register int dollar_cond = 0;
#endif
lspend = entry->symbols + entry->nsymbols;
for (lsp = entry->symbols; lsp < lspend; lsp++) {
register struct nlist *p = &lsp->nzlist.nlist;
register int type = p->n_type;
register char *name = p->n_un.n_strx + entry->strings;
register symbol *sp = getsym_soft(name);
/*
* If the symbol has an interesting definition, we could
* potentially want it.
*/
if (! (type & N_EXT)
|| (type == (N_UNDF | N_EXT) && p->n_value == 0
#ifdef DOLLAR_KLUDGE
&& name[1] != '$'
#endif
)
#ifdef SET_ELEMENT_P
|| SET_ELEMENT_P(type)
|| set_element_prefixed_p(name)
#endif
)
continue;
#ifdef DOLLAR_KLUDGE
if (name[1] == '$') {
sp = getsym_soft(&name[2]);
dollar_cond = 1;
if (!sp)
continue;
if (sp->flags & SP_REFERENCED) {
if (write_map) {
print_file_name(entry, stdout);
fprintf(stdout, " needed due to $-conditional %s\n", name);
}
return 1;
}
continue;
}
#endif
/*
* If this symbol has not been hashed, we can't be
* looking for it.
*/
if (!sp)
continue;
/*
* We don't load a file if it merely satisfies a
* common reference (see explanation above in
* symdef_library()).
*/
if ((sp->flags & GS_REFERENCED) && !sp->defined) {
/*
* This is a symbol we are looking for. It
* is either not yet defined or defined as a
* common.
*/
#ifdef DOLLAR_KLUDGE
if (dollar_cond)
continue;
#endif
if (type == (N_UNDF | N_EXT)) {
/*
* Symbol being defined as common.
* Remember this, but don't load
* subfile just for this.
*/
/*
* If it didn't used to be common, up
* the count of common symbols.
*/
if (!sp->common_size)
common_defined_global_count++;
if (sp->common_size < p->n_value)
sp->common_size = p->n_value;
if (!sp->defined)
undefined_global_sym_count--;
sp->defined = type;
continue;
}
if (sp->flags & GS_WEAK)
/* Weak symbols don't pull archive members */
continue;
if (write_map) {
print_file_name(entry, stdout);
fprintf(stdout, " needed due to %s\n", sp->name);
}
return 1;
} else {
/*
* Check for undefined symbols or commons
* in shared objects.
*/
struct localsymbol *lsp;
int wascommon = sp->defined && sp->common_size;
int iscommon = type == (N_UNDF|N_EXT) && p->n_value;
if (wascommon) {
/*
* sp was defined as common by shared object.
*/
if (iscommon && p->n_value < sp->common_size)
sp->common_size = p->n_value;
continue;
}
if (sp->sorefs == NULL)
continue;
for (lsp = sp->sorefs; lsp; lsp = lsp->next) {
int type = lsp->nzlist.nlist.n_type;
if ( (type & N_EXT) &&
(type & N_STAB) == 0 &&
type != (N_UNDF | N_EXT))
break; /* We don't need it */
}
if (lsp != NULL) {
/* There's a real definition */
if (iscommon)
/*
* But this member wants it to be
* a common; ignore it.
*/
continue;
if (N_ISWEAK(&lsp->nzlist.nlist))
/* Weak symbols don't pull archive members */
continue;
}
/*
* If the shared object referenced is undefined
* then note is as a common.
*/
if (iscommon) {
/*
* New symbol is common, just takes its
* size, but don't load.
*/
sp->common_size = p->n_value;
sp->defined = type;
continue;
}
/*
* THIS STILL MISSES the case where one shared
* object defines a common and the next defines
* more strongly; fix this someday by making
* `struct glosym' and enter_global_ref() more
* symmetric.
*/
if (write_map) {
print_file_name(entry, stdout);
fprintf(stdout,
" uneeded due to shared lib ref %s (%d)\n",
sp->name,
lsp ? lsp->nzlist.nlist.n_type : -1);
}
/*
* The shared object reference has a definition.
* Since it was previously defined in a shlib, it
* takes precedence over the new definition in the
* library member.
*/
return 0;
}
}
return 0;
}
/*
* Read the symbols of dynamic entity ENTRY into core. Assume it is already
* open, on descriptor FD.
*/
void
read_shared_object(fd, entry)
struct file_entry *entry;
int fd;
{
struct _dynamic dyn;
struct section_dispatch_table sdt;
struct nlist *np;
struct nzlist *nzp;
int n, i, has_nz = 0;
if (!(entry->flags & E_HEADER_VALID))
read_header(fd, entry);
/* Read DYNAMIC structure (first in data segment) */
if (lseek(fd, text_offset(entry) + entry->header.a_text, L_SET) ==
(off_t)-1)
err(1, "%s: lseek", get_file_name(entry));
if (read(fd, &dyn, sizeof dyn) != sizeof dyn) {
errx(1, "%s: premature EOF reading _dynamic",
get_file_name(entry));
}
md_swapin__dynamic(&dyn);
/* Check version */
switch (dyn.d_version) {
default:
errx(1, "%s: unsupported _DYNAMIC version: %d",
get_file_name(entry), dyn.d_version);
break;
case LD_VERSION_SUN:
break;
case LD_VERSION_BSD:
has_nz = 1;
break;
}
/* Read Section Dispatch Table (from data segment) */
if (lseek(fd,
text_offset(entry) + (long)dyn.d_un.d_sdt -
(DATA_START(entry->header) - N_DATOFF(entry->header)),
L_SET) == (off_t)-1)
err(1, "%s: lseek", get_file_name(entry));
if (read(fd, &sdt, sizeof sdt) != sizeof sdt)
errx(1, "%s: premature EOF reading sdt",
get_file_name(entry));
md_swapin_section_dispatch_table(&sdt);
/* Read symbols (text segment) */
n = sdt.sdt_strings - sdt.sdt_nzlist;
entry->nsymbols = n /
(has_nz ? sizeof(struct nzlist) : sizeof(struct nlist));
nzp = (struct nzlist *)(np = (struct nlist *)alloca (n));
entry->symbols = (struct localsymbol *)
xmalloc(entry->nsymbols * sizeof(struct localsymbol));
if (lseek(fd,
text_offset(entry) + (long)sdt.sdt_nzlist -
(TEXT_START(entry->header) - N_TXTOFF(entry->header)),
L_SET) == (off_t)-1)
err(1, "%s: lseek", get_file_name(entry));
if (read(fd, (char *)nzp, n) != n)
errx(1, "%s: premature EOF reading symbols ",
get_file_name(entry));
if (has_nz)
md_swapin_zsymbols(nzp, entry->nsymbols);
else
md_swapin_symbols(np, entry->nsymbols);
/* Convert to structs localsymbol */
for (i = 0; i < entry->nsymbols; i++) {
if (has_nz) {
entry->symbols[i].nzlist = *nzp++;
} else {
entry->symbols[i].nzlist.nlist = *np++;
entry->symbols[i].nzlist.nz_size = 0;
}
entry->symbols[i].symbol = NULL;
entry->symbols[i].next = NULL;
entry->symbols[i].entry = entry;
entry->symbols[i].gotslot_offset = -1;
entry->symbols[i].flags = 0;
}
/* Read strings (text segment) */
n = entry->string_size = sdt.sdt_str_sz;
entry->strings = (char *)alloca(n);
entry->strings_offset = text_offset(entry) + sdt.sdt_strings;
if (lseek(fd,
entry->strings_offset -
(TEXT_START(entry->header) - N_TXTOFF(entry->header)),
L_SET) == (off_t)-1)
err(1, "%s: lseek", get_file_name(entry));
if (read(fd, entry->strings, n) != n)
errx(1, "%s: premature EOF reading strings",
get_file_name(entry));
enter_file_symbols (entry);
entry->strings = 0;
/*
* Load any subsidiary shared objects.
*/
if (sdt.sdt_sods) {
struct sod sod;
off_t offset;
struct file_entry *prev = NULL;
offset = (off_t)sdt.sdt_sods;
while (1) {
struct file_entry *subentry;
char *libname, name[MAXPATHLEN]; /*XXX*/
subentry = (struct file_entry *)
xmalloc(sizeof(struct file_entry));
bzero(subentry, sizeof(struct file_entry));
subentry->superfile = entry;
subentry->flags = E_SECONDCLASS;
if (lseek(fd,
offset - (TEXT_START(entry->header) -
N_TXTOFF(entry->header)),
L_SET) == (off_t)-1)
err(1, "%s: lseek", get_file_name(entry));
if (read(fd, &sod, sizeof(sod)) != sizeof(sod))
errx(1, "%s: premature EOF reding sod",
get_file_name(entry));
md_swapin_sod(&sod, 1);
if (lseek(fd,
(off_t)sod.sod_name - (TEXT_START(entry->header) -
N_TXTOFF(entry->header)),
L_SET) == (off_t)-1)
err(1, "%s: lseek", get_file_name(entry));
(void)read(fd, name, sizeof(name)); /*XXX*/
if (sod.sod_library) {
int sod_major = sod.sod_major;
int sod_minor = sod.sod_minor;
libname = findshlib(name,
&sod_major, &sod_minor, 0);
if (libname == NULL)
errx(1,"no shared -l%s.%d.%d available",
name, sod.sod_major, sod.sod_minor);
subentry->filename = libname;
subentry->local_sym_name = concat("-l", name, "");
} else {
subentry->filename = strdup(name);
subentry->local_sym_name = strdup(name);
}
read_file_symbols(subentry);
if (prev)
prev->chain = subentry;
else
entry->subfiles = subentry;
prev = subentry;
fd = file_open(entry);
if ((offset = (off_t)sod.sod_next) == 0)
break;
}
}
#ifdef SUN_COMPAT
if (link_mode & SILLYARCHIVE) {
char *cp, *sa_name;
char armag[SARMAG];
int fd;
struct file_entry *subentry;
sa_name = strdup(entry->filename);
if (sa_name == NULL)
goto out;
cp = sa_name + strlen(sa_name) - 1;
while (cp > sa_name) {
if (!isdigit(*cp) && *cp != '.')
break;
--cp;
}
if (cp <= sa_name || *cp != 'o') {
/* Not in `libxxx.so.n.m' form */
free(sa_name);
goto out;
}
*cp = 'a';
if ((fd = open(sa_name, O_RDONLY, 0)) < 0)
goto out;
/* Read archive magic */
bzero(armag, SARMAG);
(void)read(fd, armag, SARMAG);
(void)close(fd);
if (strncmp(armag, ARMAG, SARMAG) != 0) {
warnx("%s: malformed silly archive",
get_file_name(entry));
goto out;
}
subentry = (struct file_entry *)
xmalloc(sizeof(struct file_entry));
bzero(subentry, sizeof(struct file_entry));
entry->silly_archive = subentry;
subentry->superfile = entry;
subentry->filename = sa_name;
subentry->local_sym_name = sa_name;
subentry->flags |= E_IS_LIBRARY;
search_library(file_open(subentry), subentry);
out:
;
}
#endif
}
#undef major
#undef minor
int
findlib(p)
struct file_entry *p;
{
int i;
int fd = -1;
int major = -1, minor = -1;
char *cp, *fname = NULL;
if (!(p->flags & E_SEARCH_DYNAMIC))
goto dot_a;
fname = findshlib(p->filename, &major, &minor, 1);
if (fname && (fd = open(fname, O_RDONLY, 0)) > 0) {
p->filename = fname;
p->lib_major = major;
p->lib_minor = minor;
p->flags &= ~E_SEARCH_DIRS;
return fd;
}
(void)free(fname);
dot_a:
p->flags &= ~E_SEARCH_DYNAMIC;
if (cp = strrchr(p->filename, '/')) {
*cp++ = '\0';
fname = concat(concat(p->filename, "/lib", cp), ".a", "");
*(--cp) = '/';
} else
fname = concat("lib", p->filename, ".a");
for (i = 0; i < n_search_dirs; i++) {
register char *path
= concat(search_dirs[i], "/", fname);
fd = open(path, O_RDONLY, 0);
if (fd > 0) {
p->filename = path;
p->flags &= ~E_SEARCH_DIRS;
break;
}
(void)free(path);
}
(void)free(fname);
return fd;
}