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macos: Read exported symbols from dylibs 

up to now we simply assumed that any undefined symbols will be
provided by some shared libs on the cmdline.  Now we check this.
This commit is contained in:
Michael Matz 2020-05-25 17:27:01 +02:00
parent fbfe6209be
commit c86760c1e9
4 changed files with 168 additions and 21 deletions
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3
libtcc.c
View File

@ -1124,7 +1124,8 @@ ST_FUNC int tcc_add_file_internal(TCCState *s1, const char *filename, int flags)
ret = tcc_load_dll(s1, fd, filename,
(flags & AFF_REFERENCED_DLL) != 0);
#else
ret = 0;
ret = macho_load_dll(s1, fd, filename,
(flags & AFF_REFERENCED_DLL) != 0);
#endif
}
break;

3
tcc.h
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@ -1531,6 +1531,8 @@ ST_FUNC void resolve_common_syms(TCCState *s1);
ST_FUNC void relocate_syms(TCCState *s1, Section *symtab, int do_resolve);
ST_FUNC void relocate_section(TCCState *s1, Section *s);
ST_FUNC ssize_t full_read(int fd, void *buf, size_t count);
ST_FUNC void *load_data(int fd, unsigned long file_offset, unsigned long size);
ST_FUNC int tcc_object_type(int fd, ElfW(Ehdr) *h);
ST_FUNC int tcc_load_object_file(TCCState *s1, int fd, unsigned long file_offset);
ST_FUNC int tcc_load_archive(TCCState *s1, int fd, int alacarte);
@ -1747,6 +1749,7 @@ PUB_FUNC int tcc_get_dllexports(const char *filename, char **pp);
/* ------------ tccmacho.c ----------------- */
#ifdef TCC_TARGET_MACHO
ST_FUNC int macho_output_file(TCCState * s1, const char *filename);
ST_FUNC int macho_load_dll(TCCState *s1, int fd, const char *filename, int lev);
#endif
/* ------------ tccrun.c ----------------- */
#ifdef TCC_IS_NATIVE

4
tccelf.c
View File

@ -2547,7 +2547,7 @@ LIBTCCAPI int tcc_output_file(TCCState *s, const char *filename)
return ret;
}
ssize_t full_read(int fd, void *buf, size_t count) {
ST_FUNC ssize_t full_read(int fd, void *buf, size_t count) {
char *cbuf = buf;
size_t rnum = 0;
while (1) {
@ -2559,7 +2559,7 @@ ssize_t full_read(int fd, void *buf, size_t count) {
}
}
static void *load_data(int fd, unsigned long file_offset, unsigned long size)
ST_FUNC void *load_data(int fd, unsigned long file_offset, unsigned long size)
{
void *data;

179
tccmacho.c
View File

@ -18,6 +18,7 @@
#include "tcc.h"
#define DEBUG_MACHO 0
#define dprintf if (DEBUG_MACHO) printf
struct mach_header {
uint32_t magic; /* mach magic number identifier */
@ -231,7 +232,9 @@ struct macho {
#define LC_SYMTAB 0x2
#define LC_DYSYMTAB 0xb
#define LC_LOAD_DYLIB 0xc
#define LC_ID_DYLIB 0xd
#define LC_LOAD_DYLINKER 0xe
#define LC_REEXPORT_DYLIB (0x1f | LC_REQ_DYLD)
#define LC_MAIN (0x28|LC_REQ_DYLD)
/* Hack for now, 46_grep.c needs fopen, but due to aliasing games
@ -375,10 +378,9 @@ static int check_symbols(TCCState *s1, struct macho *mo)
unsigned bind = ELFW(ST_BIND)(sym->st_info);
unsigned vis = ELFW(ST_VISIBILITY)(sym->st_other);
if (DEBUG_MACHO)
printf("%4d (%4d): %09llx %4d %4d %4d %3d %s\n",
sym_index, elf_index, sym->st_value,
type, bind, vis, sym->st_shndx, name);
dprintf("%4d (%4d): %09llx %4d %4d %4d %3d %s\n",
sym_index, elf_index, sym->st_value,
type, bind, vis, sym->st_shndx, name);
if (bind == STB_LOCAL) {
if (mo->ilocal == -1)
mo->ilocal = sym_index - 1;
@ -394,15 +396,12 @@ static int check_symbols(TCCState *s1, struct macho *mo)
mo->iundef = sym_index - 1;
if (ELFW(ST_BIND)(sym->st_info) == STB_WEAK)
continue;
if (get_sym_attr(s1, elf_index, 0)) {
if (find_elf_sym(s1->dynsymtab_section, name)) {
/* Mark the symbol as coming from a dylib so that
relocate_syms doesn't complain. Normally we would have
checked that any dylib in fact exports this one, and listed
those in s1->dynsymtab, which would cause us to enter this
symbol into s1->dynsym, which is checked by relocate_syms.
But for now we fake this and regard all undefined as
coming from a dylib, and we don't use the dynsymtab/dynsym
scheme. */
relocate_syms doesn't complain. Normally bind_exe_dynsyms
would do this check, and place the symbol into dynsym
which is checked by relocate_syms. But Mach-O doesn't use
bind_exe_dynsyms. */
sym->st_shndx = SHN_FROMDLL;
continue;
}
@ -589,7 +588,11 @@ static void collect_sections(TCCState *s1, struct macho *mo)
dysymlc->cmdsize = sizeof(*dysymlc);
add_lc(mo, dysymlc);
add_dylib(mo, "/usr/lib/libSystem.B.dylib");
for(i = 0; i < s1->nb_loaded_dlls; i++) {
DLLReference *dllref = s1->loaded_dlls[i];
if (dllref->level == 0)
add_dylib(mo, dllref->name);
}
mo->linkedit = new_section(s1, "LINKEDIT", SHT_LINKEDIT, SHF_ALLOC | SHF_WRITE);
/* LINKEDIT can't be empty (XXX remove once we have symbol table) */
@ -683,16 +686,14 @@ static void collect_sections(TCCState *s1, struct macho *mo)
for (s = mo->sk_to_sect[sk].s; s; s = s->prev) {
al = s->sh_addralign;
curaddr = (curaddr + al - 1) & -al;
if (DEBUG_MACHO)
printf("curaddr now 0x%llx\n", curaddr);
dprintf("curaddr now 0x%llx\n", curaddr);
s->sh_addr = curaddr;
curaddr += s->sh_size;
if (s->sh_type != SHT_NOBITS) {
fileofs = (fileofs + al - 1) & -al;
s->sh_offset = fileofs;
fileofs += s->sh_size;
if (DEBUG_MACHO)
printf("fileofs now %lld\n", fileofs);
dprintf("fileofs now %lld\n", fileofs);
}
if (sec)
mo->elfsectomacho[s->sh_num] = numsec;
@ -799,7 +800,7 @@ ST_FUNC int macho_output_file(TCCState *s1, const char *filename)
int fd, mode, file_type;
FILE *fp;
int ret = -1;
struct macho mo = {0,};
struct macho mo = {};
file_type = s1->output_type;
if (file_type == TCC_OUTPUT_OBJ)
@ -845,3 +846,145 @@ ST_FUNC int macho_output_file(TCCState *s1, const char *filename)
fclose(fp);
return ret;
}
#define FAT_MAGIC 0xcafebabe
#define FAT_CIGAM 0xbebafeca
#define FAT_MAGIC_64 0xcafebabf
#define FAT_CIGAM_64 0xbfbafeca
struct fat_header {
uint32_t magic; /* FAT_MAGIC or FAT_MAGIC_64 */
uint32_t nfat_arch; /* number of structs that follow */
};
struct fat_arch {
int cputype; /* cpu specifier (int) */
int cpusubtype; /* machine specifier (int) */
uint32_t offset; /* file offset to this object file */
uint32_t size; /* size of this object file */
uint32_t align; /* alignment as a power of 2 */
};
#define SWAP(x) (swap ? ntohl(x) : (x))
ST_FUNC int macho_load_dll(TCCState *s1, int fd, const char *filename, int lev)
{
unsigned char buf[sizeof(struct mach_header_64)];
void *buf2;
uint32_t machofs = 0;
struct fat_header fh;
struct mach_header mh;
struct load_command *lc;
int i, swap = 0;
const char *soname = filename;
struct nlist_64 *symtab = 0;
uint32_t nsyms = 0;
char *strtab = 0;
uint32_t strsize = 0;
uint32_t iextdef = 0;
uint32_t nextdef = 0;
DLLReference *dllref;
again:
if (full_read(fd, buf, sizeof(buf)) != sizeof(buf))
return -1;
memcpy(&fh, buf, sizeof(fh));
if (fh.magic == FAT_MAGIC || fh.magic == FAT_CIGAM) {
struct fat_arch *fa = load_data(fd, sizeof(fh),
fh.nfat_arch * sizeof(*fa));
swap = fh.magic == FAT_CIGAM;
for (i = 0; i < SWAP(fh.nfat_arch); i++)
if (SWAP(fa[i].cputype) == 0x01000007 /* CPU_TYPE_X86_64 */
&& SWAP(fa[i].cpusubtype) == 3) /* CPU_SUBTYPE_X86_ALL */
break;
if (i == SWAP(fh.nfat_arch)) {
tcc_free(fa);
return -1;
}
machofs = SWAP(fa[i].offset);
tcc_free(fa);
lseek(fd, machofs, SEEK_SET);
goto again;
} else if (fh.magic == FAT_MAGIC_64 || fh.magic == FAT_CIGAM_64) {
tcc_warning("%s: Mach-O fat 64bit files of type 0x%x not handled",
filename, fh.magic);
return -1;
}
memcpy(&mh, buf, sizeof(mh));
if (mh.magic != MH_MAGIC_64)
return -1;
dprintf("found Mach-O at %d\n", machofs);
buf2 = load_data(fd, machofs + sizeof(struct mach_header_64), mh.sizeofcmds);
for (i = 0, lc = buf2; i < mh.ncmds; i++) {
dprintf("lc %2d: 0x%08x\n", i, lc->cmd);
if (lc->cmd == LC_SYMTAB) {
struct symtab_command *sc = (struct symtab_command*)lc;
nsyms = sc->nsyms;
symtab = load_data(fd, machofs + sc->symoff, nsyms * sizeof(*symtab));
strsize = sc->strsize;
strtab = load_data(fd, machofs + sc->stroff, strsize);
} else if (lc->cmd == LC_ID_DYLIB) {
struct dylib_command *dc = (struct dylib_command*)lc;
soname = (char*)lc + dc->name;
dprintf(" ID_DYLIB %d 0x%x 0x%x %s\n",
dc->timestamp, dc->current_version,
dc->compatibility_version, soname);
} else if (lc->cmd == LC_REEXPORT_DYLIB) {
struct dylib_command *dc = (struct dylib_command*)lc;
char *name = (char*)lc + dc->name;
dprintf(" REEXPORT %s\n", name);
int subfd = open(name, O_RDONLY | O_BINARY);
if (subfd < 0)
tcc_warning("can't open %s (reexported from %s)", name, filename);
else {
/* Hopefully the REEXPORTs never form a cycle, we don't check
for that! */
macho_load_dll(s1, subfd, name, lev + 1);
close(subfd);
}
} else if (lc->cmd == LC_DYSYMTAB) {
struct dysymtab_command *dc = (struct dysymtab_command*)lc;
iextdef = dc->iextdefsym;
nextdef = dc->nextdefsym;
}
lc = (struct load_command*) ((char*)lc + lc->cmdsize);
}
/* if the dll is already loaded, do not load it */
for(i = 0; i < s1->nb_loaded_dlls; i++) {
dllref = s1->loaded_dlls[i];
if (!strcmp(soname, dllref->name)) {
/* but update level if needed */
if (lev < dllref->level)
dllref->level = lev;
goto the_end;
}
}
dllref = tcc_mallocz(sizeof(DLLReference) + strlen(soname));
dllref->level = lev;
strcpy(dllref->name, soname);
dynarray_add(&s1->loaded_dlls, &s1->nb_loaded_dlls, dllref);
if (!nsyms || !nextdef)
tcc_warning("%s doesn't export any symbols?", filename);
//dprintf("symbols (all):\n");
dprintf("symbols (exported):\n");
dprintf(" n: typ sec desc value name\n");
//for (i = 0; i < nsyms; i++) {
for (i = iextdef; i < iextdef + nextdef; i++) {
struct nlist_64 *sym = symtab + i;
dprintf("%5d: %3d %3d 0x%04x 0x%016llx %s\n",
i, sym->n_type, sym->n_sect, sym->n_desc, sym->n_value,
strtab + sym->n_strx);
set_elf_sym(s1->dynsymtab_section, 0, 0,
ELFW(ST_INFO)(STB_GLOBAL, STT_NOTYPE),
0, SHN_UNDEF, strtab + sym->n_strx);
}
the_end:
tcc_free(strtab);
tcc_free(symtab);
tcc_free(buf2);
return 0;
}