runtime/objc-file.mm

   1 /*
   2  * Copyright (c) 1999-2007 Apple Inc.  All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #if __OBJC2__
  25
  26 #include "objc-private.h"
  27 #include "objc-file.h"
  28
  29 #if TARGET_IPHONE_SIMULATOR
  30 // getsectiondata() not yet available
  31
  32 // 1. Find segment with file offset == 0 and file size != 0. This segment's
  33 //    contents span the Mach-O header. (File size of 0 is .bss, for example)
  34 // 2. Slide is header's address - segment's preferred address
  35 static ptrdiff_t
  36 objc_getImageSlide(const struct mach_header *header)
  37 {
  38     unsigned long i;
  39     const struct segment_command *sgp = (const struct segment_command *)(header + 1);
  40
  41     for (i = 0; i < header->ncmds; i++){
  42         if (sgp->cmd == LC_SEGMENT) {
  43             if (sgp->fileoff == 0  &&  sgp->filesize != 0) {
  44                 return (uintptr_t)header - (uintptr_t)sgp->vmaddr;
  45             }
  46         }
  47         sgp = (const struct segment_command *)((char *)sgp + sgp->cmdsize);
  48     }
  49
  50     // uh-oh
  51     _objc_fatal("could not calculate VM slide for image");
  52     return 0;  // not reached
  53 }
  54
  55 uint8_t *
  56 objc_getsectiondata(const struct mach_header *mh, const char *segname, const char *sectname, unsigned long *outSize)
  57 {
  58     uint32_t size = 0;
  59
  60     char *data = getsectdatafromheader(mh, segname, sectname, &size);
  61     if (data) {
  62         *outSize = size;
  63         return (uint8_t *)data + objc_getImageSlide(mh);
  64     } else {
  65         *outSize = 0;
  66         return NULL;
  67     }
  68 }
  69
  70 static const struct segment_command *
  71 objc_getsegbynamefromheader(const mach_header *head, const char *segname)
  72 {
  73     const struct segment_command *sgp;
  74     unsigned long i;
  75
  76     sgp = (const struct segment_command *) (head + 1);
  77     for (i = 0; i < head->ncmds; i++){
  78         if (sgp->cmd == LC_SEGMENT) {
  79             if (strncmp(sgp->segname, segname, sizeof(sgp->segname)) == 0) {
  80                 return sgp;
  81             }
  82         }
  83         sgp = (const struct segment_command *)((char *)sgp + sgp->cmdsize);
  84     }
  85     return NULL;
  86 }
  87
  88 uint8_t *
  89 objc_getsegmentdata(const struct mach_header *mh, const char *segname, unsigned long *outSize)
  90 {
  91     const struct segment_command *seg;
  92
  93     seg = objc_getsegbynamefromheader(mh, segname);
  94     if (seg) {
  95         *outSize = seg->vmsize;
  96         return (uint8_t *)seg->vmaddr + objc_getImageSlide(mh);
  97     } else {
  98         *outSize = 0;
  99         return NULL;
 100     }
 101 }
 102
 103 // TARGET_IPHONE_SIMULATOR
 104 #endif
 105
 106 #define GETSECT(name, type, sectname)                                   \
 107     type *name(const header_info *hi, size_t *outCount)  \
 108     {                                                                   \
 109         unsigned long byteCount = 0;                                    \
 110         type *data = (type *)                                           \
 111             getsectiondata(hi->mhdr, SEG_DATA, sectname, &byteCount);   \
 112         *outCount = byteCount / sizeof(type);                           \
 113         return data;                                                    \
 114     }
 115
 116 //      function name                 content type     section name
 117 GETSECT(_getObjc2SelectorRefs,        SEL,             "__objc_selrefs");
 118 GETSECT(_getObjc2MessageRefs,         message_ref_t,   "__objc_msgrefs");
 119 GETSECT(_getObjc2ClassRefs,           class_t *,       "__objc_classrefs");
 120 GETSECT(_getObjc2SuperRefs,           class_t *,       "__objc_superrefs");
 121 GETSECT(_getObjc2ClassList,           classref_t,       "__objc_classlist");
 122 GETSECT(_getObjc2NonlazyClassList,    classref_t,       "__objc_nlclslist");
 123 GETSECT(_getObjc2CategoryList,        category_t *,    "__objc_catlist");
 124 GETSECT(_getObjc2NonlazyCategoryList, category_t *,    "__objc_nlcatlist");
 125 GETSECT(_getObjc2ProtocolList,        protocol_t *,    "__objc_protolist");
 126 GETSECT(_getObjc2ProtocolRefs,        protocol_t *,    "__objc_protorefs");
 127
 128
 129 objc_image_info *
 130 _getObjcImageInfo(const headerType *mhdr, size_t *outBytes)
 131 {
 132     unsigned long byteCount = 0;
 133     objc_image_info *data = (objc_image_info *)
 134         getsectiondata(mhdr, SEG_DATA, "__objc_imageinfo", &byteCount);
 135     *outBytes = byteCount;
 136     return data;
 137 }
 138
 139
 140 static const segmentType *
 141 getsegbynamefromheader(const headerType *head, const char *segname)
 142 {
 143     const segmentType *sgp;
 144     unsigned long i;
 145
 146     sgp = (const segmentType *) (head + 1);
 147     for (i = 0; i < head->ncmds; i++){
 148         if (sgp->cmd == SEGMENT_CMD) {
 149             if (strncmp(sgp->segname, segname, sizeof(sgp->segname)) == 0) {
 150                 return sgp;
 151             }
 152         }
 153         sgp = (const segmentType *)((char *)sgp + sgp->cmdsize);
 154     }
 155     return NULL;
 156 }
 157
 158 BOOL
 159 _hasObjcContents(const header_info *hi)
 160 {
 161     // Look for a __DATA,__objc* section other than __DATA,__objc_imageinfo
 162     const segmentType *seg = getsegbynamefromheader(hi->mhdr, "__DATA");
 163     if (!seg) return NO;
 164
 165     const sectionType *sect;
 166     uint32_t i;
 167     for (i = 0; i < seg->nsects; i++) {
 168         sect = ((const sectionType *)(seg+1))+i;
 169         if (0 == strncmp(sect->sectname, "__objc_", 7)  &&
 170             0 != strncmp(sect->sectname, "__objc_imageinfo", 16))
 171         {
 172             return YES;
 173         }
 174     }
 175
 176     return NO;
 177 }
 178
 179 #endif