diff options
Diffstat (limited to 'libexec/rtld-aout/rtld.c')
| -rw-r--r-- | libexec/rtld-aout/rtld.c | 51 |
1 files changed, 33 insertions, 18 deletions
diff --git a/libexec/rtld-aout/rtld.c b/libexec/rtld-aout/rtld.c index efe912b..b331cde 100644 --- a/libexec/rtld-aout/rtld.c +++ b/libexec/rtld-aout/rtld.c @@ -27,7 +27,7 @@ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * - * $Id: rtld.c,v 1.49 1997/09/18 13:55:45 phk Exp $ + * $Id: rtld.c,v 1.50 1997/11/29 03:32:47 jdp Exp $ */ #include <sys/param.h> @@ -234,7 +234,7 @@ static int reloc_map __P((struct so_map *, int)); static void reloc_copy __P((struct so_map *)); static void init_dag __P((struct so_map *)); static void init_sods __P((struct so_list *)); -static void init_internal_malloc __P((struct _dynamic *)); +static void init_internal_malloc __P((void)); static void init_external_malloc __P((void)); static int call_map __P((struct so_map *, char *)); static char *findhint __P((char *, int, int *)); @@ -347,7 +347,7 @@ struct _dynamic *dp; crtp->crt_dp->d_entry = &ld_entry; /* _DYNAMIC */ /* Initialize our internal malloc package. */ - init_internal_malloc(crtp->crt_dp); + init_internal_malloc(); /* Setup out (private) environ variable */ environ = crtp->crt_ep; @@ -2230,26 +2230,34 @@ static char *rtld_alloc_lev; * main program's sbrk arena. */ static void -init_internal_malloc(dp) - struct _dynamic *dp; +init_internal_malloc __P((void)) { - struct so_map tmp_map; - struct somap_private map_private; - struct nzlist *np; + const struct exec *hdr; /* * Before anything calls sbrk or brk, we have to initialize - * its idea of the current break level to the main program's - * "_end" symbol, rather than that of the dynamic linker. In - * order to do that, we need to look up the value of the main - * program's "_end" symbol. We set up a temporary link map - * entry for the main program so that we can do the lookup. + * its idea of the current break level to just beyond the main + * program's address space. Strictly speaking, the right + * way to do that is to look up the value of "_end" in the + * application's run time symbol table. + * + * That is what we used to do, and it works correctly for + * every valid program. Unfortunately, it doesn't work right + * for "unexec"ed versions of emacs. They are incorrectly + * generated with a wrong value for "_end". (xemacs gets it + * right.) + * + * To work around this, we peek at the exec header to get the + * sizes of the text, data, and bss segments. Luckily, the + * header is in memory at the start of the first mapped page. + * From the segment sizes, we can calculate a proper initial + * value for the break level. */ - init_link_map(&tmp_map, &map_private, NULL, NULL, NULL, NULL, dp); - np = lookup_in_obj(END_SYM, sym_hash(END_SYM), &tmp_map, 1); - if (np == NULL) - errx(1, "Main program has no symbol \"%s\"", END_SYM); - rtld_alloc_lev = curbrk = minbrk = (char *)np->nz_value; + hdr = (const struct exec *)PAGSIZ; + if (N_BADMAG(*hdr)) /* Sanity check */ + errx(1, "Cannot find program's a.out header"); + rtld_alloc_lev = curbrk = minbrk = + (char *)hdr + hdr->a_text + hdr->a_data + hdr->a_bss; } /* @@ -2267,6 +2275,13 @@ init_external_malloc __P((void)) *(char **)(sym_addr(CURBRK_SYM)) = curbrk; /* + * Set the minimum break level too. Otherwise, "unexec"ed + * emacs sets the break too low and wipes out our tables of + * shared objects. + */ + *(char **)(sym_addr(MINBRK_SYM)) = curbrk; + + /* * Set up pointers to the program's allocation functions, so * that we can use them from now on. */ |
