ref: 733c5d6645b133b60d304c38fcb1398f94d0618c
dir: /sys/src/cmd/hgfs/patch.c/
#include <u.h> #include <libc.h> #include <thread.h> #include "dat.h" #include "fns.h" int fcopy(int dfd, int sfd, vlong off, vlong len) { uchar buf[BUFSZ]; int n; while(len != 0){ n = BUFSZ; if(len > 0 && n > len) n = len; if((n = pread(sfd, buf, n, off)) < 0) return -1; if(n == 0) return len > 0 ? -1 : 0; if(write(dfd, buf, n) != n) return -1; if(off >= 0) off += n; if(len > 0) len -= n; } return 0; } static uchar patchmark[12] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, }; int fpatchmark(int pfd, char *) { if(write(pfd, patchmark, 12) != 12) return -1; return 0; } typedef struct Frag Frag; struct Frag { Frag *next; int fd; vlong len; vlong off; }; int fpatch(int ofd, int bfd, int pfd) { vlong off, fstart, fend, start, end, len; int err, front, back; Frag *h, *f, *p; uchar buf[12]; h = nil; err = -1; if(bfd >= 0){ h = malloc(sizeof(Frag)); if(h == nil) goto errout; h->next = nil; h->off = 0; h->fd = bfd; h->len = seek(h->fd, 0, 2); if(h->len < 0) goto errout; } off = 0; while(pfd >= 0){ if(readn(pfd, buf, 12) != 12) break; if(memcmp(buf, patchmark, 12) == 0){ off = 0; continue; } start = buf[0]<<24 | buf[1]<<16 | buf[2]<<8 | buf[3]; end = buf[4]<<24 | buf[5]<<16 | buf[6]<<8 | buf[7]; len = buf[8]<<24 | buf[9]<<16 | buf[10]<<8 | buf[11]; if(start > end){ werrstr("bad patch: start > end"); goto errout; } start += off; end += off; off += start + len - end; fstart = 0; for(f = h; f; f = f->next, fstart = fend){ fend = fstart + f->len; if(fend <= start) continue; if(fstart >= end) break; front = start > fstart; back = end < fend; if(front && back){ p = malloc(sizeof(Frag)); if(p == nil) goto errout; *p = *f; f->next = p; f->len = start - fstart; p->off += end - fstart; p->len -= end - fstart; break; } else if(back){ f->off += end - fstart; f->len -= end - fstart; break; } else if(front){ f->len = start - fstart; } else { f->len = 0; } } fstart = 0; for(p = nil, f = h; f && fstart < start; p = f, f = f->next) fstart += f->len; f = malloc(sizeof(Frag)); if(f == nil) goto errout; f->fd = pfd; f->len = len; f->off = seek(f->fd, 0, 1); if(p){ f->next = p->next; p->next = f; } else { f->next = h; h = f; } if(f->off < 0) goto errout; if(seek(pfd, f->len, 1) < 0) goto errout; } for(f = h; f; f = f->next) if(fcopy(ofd, f->fd, f->off, f->len) < 0) goto errout; err = 0; errout: while(f = h){ h = f->next; free(f); } return err; }