ref: 12e226ac6798412271020d42645f69138715c519
dir: /utils/libmach/access.c/
/* * functions to read and write an executable or file image */ #include <lib9.h> #include <bio.h> #include "mach.h" static int mget(Map*, uvlong, void*, int); static int mput(Map*, uvlong, void*, int); static struct segment* reloc(Map*, uvlong, vlong*); /* * routines to get/put various types */ int geta(Map *map, uvlong addr, uvlong *x) { ulong l; uvlong vl; if (mach->szaddr == 8){ if (get8(map, addr, &vl) < 0) return -1; *x = vl; return 1; } if (get4(map, addr, &l) < 0) return -1; *x = l; return 1; } int get8(Map *map, uvlong addr, uvlong *x) { if (!map) { werrstr("get8: invalid map"); return -1; } if (map->nsegs == 1 && map->seg[0].fd < 0) { *x = addr; return 1; } if (mget(map, addr, x, 8) < 0) return -1; *x = machdata->swav(*x); return 1; } int get4(Map *map, uvlong addr, ulong *x) { if (!map) { werrstr("get4: invalid map"); return -1; } if (map->nsegs == 1 && map->seg[0].fd < 0) { *x = addr; return 1; } if (mget(map, addr, x, 4) < 0) return -1; *x = machdata->swal(*x); return 1; } int get2(Map *map, uvlong addr, ushort *x) { if (!map) { werrstr("get2: invalid map"); return -1; } if (map->nsegs == 1 && map->seg[0].fd < 0) { *x = addr; return 1; } if (mget(map, addr, x, 2) < 0) return -1; *x = machdata->swab(*x); return 1; } int get1(Map *map, uvlong addr, uchar *x, int size) { uchar *cp; if (!map) { werrstr("get1: invalid map"); return -1; } if (map->nsegs == 1 && map->seg[0].fd < 0) { cp = (uchar*)&addr; while (cp < (uchar*)(&addr+1) && size-- > 0) *x++ = *cp++; while (size-- > 0) *x++ = 0; } else return mget(map, addr, x, size); return 1; } int puta(Map *map, uvlong addr, uvlong v) { if (mach->szaddr == 8) return put8(map, addr, v); return put4(map, addr, v); } int put8(Map *map, uvlong addr, uvlong v) { if (!map) { werrstr("put8: invalid map"); return -1; } v = machdata->swav(v); return mput(map, addr, &v, 8); } int put4(Map *map, uvlong addr, ulong v) { if (!map) { werrstr("put4: invalid map"); return -1; } v = machdata->swal(v); return mput(map, addr, &v, 4); } int put2(Map *map, uvlong addr, ushort v) { if (!map) { werrstr("put2: invalid map"); return -1; } v = machdata->swab(v); return mput(map, addr, &v, 2); } int put1(Map *map, uvlong addr, uchar *v, int size) { if (!map) { werrstr("put1: invalid map"); return -1; } return mput(map, addr, v, size); } static int spread(struct segment *s, void *buf, int n, uvlong off) { uvlong base; static struct { struct segment *s; char a[8192]; uvlong off; } cache; if(s->cache){ base = off&~(sizeof cache.a-1); if(cache.s != s || cache.off != base){ cache.off = ~0; if(seek(s->fd, base, 0) >= 0 && readn(s->fd, cache.a, sizeof cache.a) == sizeof cache.a){ cache.s = s; cache.off = base; } } if(cache.s == s && cache.off == base){ off &= sizeof cache.a-1; if(off+n > sizeof cache.a) n = sizeof cache.a - off; memmove(buf, cache.a+off, n); return n; } } return pread(s->fd, buf, n, off); } static int mget(Map *map, uvlong addr, void *buf, int size) { uvlong off; int i, j, k; struct segment *s; s = reloc(map, addr, (vlong*)&off); if (!s) return -1; if (s->fd < 0) { werrstr("unreadable map"); return -1; } if (s->mget) return s->mget(s, addr, off, buf, size); for (i = j = 0; i < 2; i++) { /* in case read crosses page */ k = spread(s, (void*)((uchar *)buf+j), size-j, off+j); if (k < 0) { werrstr("can't read address %llux: %r", addr); return -1; } j += k; if (j == size) return j; } werrstr("partial read at address %llux (size %d j %d)", addr, size, j); return -1; } static int mput(Map *map, uvlong addr, void *buf, int size) { vlong off; int i, j, k; struct segment *s; s = reloc(map, addr, &off); if (!s) return -1; if (s->fd < 0) { werrstr("unwritable map"); return -1; } if (s->mput) return s->mput(s, addr, off, buf, size); seek(s->fd, off, 0); for (i = j = 0; i < 2; i++) { /* in case read crosses page */ k = write(s->fd, buf, size-j); if (k < 0) { werrstr("can't write address %llux: %r", addr); return -1; } j += k; if (j == size) return j; } werrstr("partial write at address %llux", addr); return -1; } /* * convert address to file offset; returns nonzero if ok */ static struct segment* reloc(Map *map, uvlong addr, vlong *offp) { int i; for (i = 0; i < map->nsegs; i++) { if (map->seg[i].inuse) if (map->seg[i].b <= addr && addr < map->seg[i].e) { *offp = addr + map->seg[i].f - map->seg[i].b; return &map->seg[i]; } } werrstr("can't translate address %llux", addr); return 0; }