dwarfabbrev.c (2629B)
1 /* 2 * Dwarf abbreviation parsing code. 3 * 4 * The convention here is that calling dwarfgetabbrevs relinquishes 5 * access to any abbrevs returned previously. Will have to add 6 * explicit reference counting if this turns out not to be acceptable. 7 */ 8 9 #include <u.h> 10 #include <libc.h> 11 #include <bio.h> 12 #include "elf.h" 13 #include "dwarf.h" 14 15 static int parseabbrevs(Dwarf*, ulong, DwarfAbbrev*, DwarfAttr*, int*, int*); 16 DwarfAbbrev *dwarfgetabbrev(Dwarf*, ulong, ulong); 17 18 static int 19 loadabbrevs(Dwarf *d, ulong off, DwarfAbbrev **aa) 20 { 21 int nattr, nabbrev; 22 DwarfAbbrev *abbrev; 23 DwarfAttr *attr; 24 25 if(d->acache.off == off && d->acache.na){ 26 *aa = d->acache.a; 27 return d->acache.na; 28 } 29 30 /* two passes - once to count, then allocate, then a second to copy */ 31 if(parseabbrevs(d, off, nil, nil, &nabbrev, &nattr) < 0) 32 return -1; 33 34 abbrev = malloc(nabbrev*sizeof(DwarfAbbrev) + nattr*sizeof(DwarfAttr)); 35 attr = (DwarfAttr*)(abbrev+nabbrev); 36 37 if(parseabbrevs(d, off, abbrev, attr, nil, nil) < 0){ 38 free(abbrev); 39 return -1; 40 } 41 42 free(d->acache.a); 43 d->acache.a = abbrev; 44 d->acache.na = nabbrev; 45 d->acache.off = off; 46 47 *aa = abbrev; 48 return nabbrev; 49 } 50 51 static int 52 parseabbrevs(Dwarf *d, ulong off, DwarfAbbrev *abbrev, DwarfAttr *attr, int *pnabbrev, int *pnattr) 53 { 54 int i, nabbrev, nattr, haskids; 55 ulong num, tag, name, form; 56 DwarfBuf b; 57 58 if(off >= d->abbrev.len){ 59 werrstr("bad abbrev section offset 0x%lux >= 0x%lux\n", off, d->abbrev.len); 60 return -1; 61 } 62 63 memset(&b, 0, sizeof b); 64 b.p = d->abbrev.data + off; 65 b.ep = d->abbrev.data + d->abbrev.len; 66 67 nabbrev = 0; 68 nattr = 0; 69 for(;;){ 70 if(b.p == nil){ 71 werrstr("malformed abbrev data"); 72 return -1; 73 } 74 num = dwarfget128(&b); 75 if(num == 0) 76 break; 77 tag = dwarfget128(&b); 78 haskids = dwarfget1(&b); 79 for(i=0;; i++){ 80 name = dwarfget128(&b); 81 form = dwarfget128(&b); 82 if(name == 0 && form == 0) 83 break; 84 if(attr){ 85 attr[i].name = name; 86 attr[i].form = form; 87 } 88 } 89 if(abbrev){ 90 abbrev->num = num; 91 abbrev->tag = tag; 92 abbrev->haskids = haskids; 93 abbrev->attr = attr; 94 abbrev->nattr = i; 95 abbrev++; 96 attr += i; 97 } 98 nabbrev++; 99 nattr += i; 100 } 101 if(pnabbrev) 102 *pnabbrev = nabbrev; 103 if(pnattr) 104 *pnattr = nattr; 105 return 0; 106 } 107 108 static DwarfAbbrev* 109 findabbrev(DwarfAbbrev *a, int na, ulong num) 110 { 111 int i; 112 113 for(i=0; i<na; i++) 114 if(a[i].num == num) 115 return &a[i]; 116 werrstr("abbrev not found"); 117 return nil; 118 } 119 120 DwarfAbbrev* 121 dwarfgetabbrev(Dwarf *d, ulong off, ulong num) 122 { 123 DwarfAbbrev *a; 124 int na; 125 126 if((na = loadabbrevs(d, off, &a)) < 0){ 127 werrstr("loadabbrevs: %r"); 128 return nil; 129 } 130 return findabbrev(a, na, num); 131 }