ld.so: be more mmap()-behaviour-independent

. if the layout of virtual address regions as returned
	  by mmap() without a location hint changes, ld.so could
	  trip itself up (under minix). this change allocates
	  the full size it needs for every object that's loaded
	  so that if that succeeds, it's sure there's virtual address
	  space for the whole thing no matter what other bits happen
	  to be there already.

	. this fix exposed a bug in the test; at atexit() execution
	  time the loaded object is unmapped, so that part of the
	  test is removed.

libexec/ld.elf_so/map_object.c

@@ -38,6 +38,7 @@ __RCSID("$NetBSD: map_object.c,v 1.41 2010/10/16 10:27:07 skrll Exp $");
 #endif /* not lint */
 
 #include <errno.h>
+#include <stdio.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
@@ -49,55 +50,27 @@ __RCSID("$NetBSD: map_object.c,v 1.41 2010/10/16 10:27:07 skrll Exp $");
 #include "debug.h"
 #include "rtld.h"
 
+#ifdef __minix
+#define munmap minix_munmap
+#endif
+
+#define MINIXVERBOSE 0
+
 static int protflags(int);	/* Elf flags -> mmap protection */
 
 #define EA_UNDEF		(~(Elf_Addr)0)
 
-#ifdef __minix
+static void Pread(void *addr, size_t size, int fd, off_t off)
-#define mmap	minix_mmap_emulator
-#define munmap	minix_munmap
-
-/* for minix, ignore MAP_SHARED and MAP_FILE for now. */
-#define MAP_SHARED 0
-#define MAP_FILE 0
-#endif
-
-#undef MINIXVERBOSE
-
-static void * minix_mmap_emulator(void *addrhint, size_t size, int prot, int flags, int fd, off_t off)
 {
-	void *ret;
+	int s;
-	int mapflags;
+	if((s=pread(fd,addr, size, off)) < 0) {
-	size_t s;
+		_rtld_error("pread failed");
-
+		exit(1);
-	mapflags = flags & (MAP_FIXED);
-
-#ifdef MINIXVERBOSE
-	if(addrhint) {
-		fprintf(stderr, "0x%lx-0x%lx requested\n", addrhint,
-			(char *) addrhint + size);
 	}
+
+#if MINIXVERBOSE
+	fprintf(stderr, "read 0x%lx bytes from offset 0x%lx to addr 0x%lx\n", size, off, addr);
 #endif
-
-	if((ret = minix_mmap(addrhint, size, PROT_READ|PROT_WRITE,
-		MAP_ANON|MAP_PRIVATE|MAP_PREALLOC|mapflags, -1, 0)) == MAP_FAILED) {
-		return ret;
-	}
-
-	if(!(mapflags & MAP_ANON)) {
-		if((s=pread(fd, ret, size, off)) <= 0) {
-			munmap(ret, size);
-			return MAP_FAILED;
-		}
-	}
-
-#ifdef MINIXVERBOSE
-	fprintf(stderr, "0x%lx-0x%lx mapped\n",
-		ret, (char *) ret + size);
-
-#endif
-
-	return ret;
 }
 
 /*
@@ -159,8 +132,17 @@ _rtld_map_object(const char *path, int fd, const struct stat *sb)
 		obj->ino = sb->st_ino;
 	}
 
+#ifdef __minix
+	ehdr = minix_mmap(NULL, _rtld_pagesz, PROT_READ|PROT_WRITE,
+		MAP_PREALLOC|MAP_ANON, -1, (off_t)0);
+	Pread(ehdr, _rtld_pagesz, fd, 0);
+#if MINIXVERBOSE
+	fprintf(stderr, "minix mmap for header: 0x%lx\n", ehdr);
+#endif
+#else
 	ehdr = mmap(NULL, _rtld_pagesz, PROT_READ, MAP_FILE | MAP_SHARED, fd,
 	    (off_t)0);
+#endif
 	obj->ehdr = ehdr;
 	if (ehdr == MAP_FAILED) {
 		_rtld_error("%s: read error: %s", path, xstrerror(errno));
@@ -349,9 +331,12 @@ _rtld_map_object(const char *path, int fd, const struct stat *sb)
 	mapbase = mmap(base_addr, mapsize, text_flags,
 	    mapflags | MAP_FILE | MAP_PRIVATE, fd, base_offset);
 #else
-	/* minix doesn't want overlapping mmap()s */
+	mapbase = minix_mmap(base_addr, mapsize, PROT_READ|PROT_WRITE,
-	mapbase = mmap(base_addr, obj->textsize, text_flags,
+	    MAP_ANON | MAP_PREALLOC, -1, 0);
-	    mapflags | MAP_FILE | MAP_PRIVATE, fd, base_offset);
+#if MINIXVERBOSE
+	fprintf(stderr, "minix mmap for whole block: 0x%lx-0x%lx\n", mapbase, mapbase+mapsize);
+#endif
+	Pread(mapbase, obj->textsize, fd, 0);
 #endif
 	if (mapbase == MAP_FAILED) {
 		_rtld_error("mmap of entire address space failed: %s",
@@ -361,13 +346,18 @@ _rtld_map_object(const char *path, int fd, const struct stat *sb)
 
 	/* Overlay the data segment onto the proper region. */
 	data_addr = mapbase + (data_vaddr - base_vaddr);
+#ifdef __minix
+	Pread(data_addr, data_vlimit - data_vaddr, fd, data_offset);
+#else
 	if (mmap(data_addr, data_vlimit - data_vaddr, data_flags,
 	    MAP_FILE | MAP_PRIVATE | MAP_FIXED, fd, data_offset) ==
 	    MAP_FAILED) {
 		_rtld_error("mmap of data failed: %s", xstrerror(errno));
 		goto bad;
 	}
+#endif
 
+#ifndef __minix
 	bsssize= base_vlimit - data_vlimit;
    if(bsssize > 0) {
 	/* Overlay the bss segment onto the proper region. */
@@ -384,7 +374,6 @@ _rtld_map_object(const char *path, int fd, const struct stat *sb)
 	gap_addr = mapbase + round_up(text_vlimit - base_vaddr);
 	gap_size = data_addr - gap_addr;
 
-#ifndef __minix
 	if (gap_size != 0 && mprotect(gap_addr, gap_size, PROT_NONE) == -1) {
 		_rtld_error("mprotect of text -> data gap failed: %s",
 		    xstrerror(errno));

test/mod.c

@@ -18,7 +18,6 @@ long modfunction(long v1, long *argcookie, long v2) {
   }
   *argcookie = MAGIC3;
   cookie = MAGIC2;
-  atexit(exithandler);
   return MAGIC1;
 }