ref: c1d40df49550393f3afe53fb6e6d500dfa8eb7a8
dir: /sys/src/cmd/ip/ftpfs/file.c/
#include <u.h> #include <libc.h> #include <String.h> #include "ftpfs.h" enum { Chunk= 1024, /* chunk size for buffered data */ Nfile= 128, /* maximum number of cached files */ }; /* a file (with cached data) */ struct File { char *mem; /* part of file cached in memory */ ulong len; /* length of cached data */ long off; /* current offset into tpath */ short fd; /* fd to cache file */ char inuse; char dirty; ulong atime; /* time of last access */ Node *node; char *template; }; static File files[Nfile]; static ulong now; static int ntmp; /* * lookup a file, create one if not found. if there are no * free files, free the last oldest clean one. */ static File* fileget(Node *node) { File *fp; File *oldest; fp = node->fp; if(fp) return fp; oldest = 0; for(fp = files; fp < &files[Nfile]; fp++){ if(fp->inuse == 0) break; if(fp->dirty == 0 && (oldest == 0 || oldest->atime > fp->atime)) oldest = fp; } if(fp == &files[Nfile]){ uncache(oldest->node); fp = oldest; } node->fp = fp; fp->node = node; fp->atime = now++; fp->inuse = 1; fp->fd = -1; if(fp->mem){ free(fp->mem); fp->mem = nil; } return fp; } /* * free a cached file */ void filefree(Node *node) { File *fp; fp = node->fp; if(fp == 0) return; if(fp->fd >= 0){ ntmp--; close(fp->fd); remove(fp->template); free(fp->template); fp->template = 0; } fp->fd = -1; if(fp->mem){ free(fp->mem); fp->mem = nil; } fp->len = 0; fp->inuse = 0; fp->dirty = 0; node->fp = 0; } /* * satisfy read first from in memory chunk and then from temporary * file. It's up to the caller to make sure that the file is valid. */ int fileread(Node *node, char *a, long off, int n) { int sofar; int i; File *fp; fp = node->fp; if(fp == 0) fatal("fileread"); if(off + n > fp->len) n = fp->len - off; for(sofar = 0; sofar < n; sofar += i, off += i, a += i){ if(off >= fp->len) return sofar; if(off < Chunk){ i = n; if(off + i > Chunk) i = Chunk - off; memmove(a, fp->mem + off, i); continue; } if(fp->off != off) if(seek(fp->fd, off, 0) < 0){ fp->off = -1; return -1; } i = read(fp->fd, a, n-sofar); if(i < 0){ fp->off = -1; return -1; } if(i == 0) break; fp->off = off + i; } return sofar; } void uncachedir(Node *parent, Node *child) { Node *sp; if(parent == 0 || parent == child) return; for(sp = parent->children; sp; sp = sp->sibs) if(sp->opens == 0) if(sp != child) if(sp->fp != nil) if(sp->fp->dirty == 0) if(sp->fp->fd >= 0){ filefree(sp); UNCACHED(sp); } } static int createtmp(File *fp) { char template[32]; strcpy(template, "/tmp/ftpXXXXXXXXXXX"); mktemp(template); if(strcmp(template, "/") == 0){ fprint(2, "ftpfs can't create tmp file %s: %r\n", template); return -1; } if(ntmp >= 16) uncachedir(fp->node->parent, fp->node); fp->fd = create(template, ORDWR|ORCLOSE, 0600); fp->template = strdup(template); fp->off = 0; ntmp++; return fp->fd; } /* * write cached data (first Chunk bytes stay in memory) */ int filewrite(Node *node, char *a, long off, int n) { int i, sofar; File *fp; fp = fileget(node); if(fp->mem == nil){ fp->mem = malloc(Chunk); if(fp->mem == nil) return seterr("out of memory"); } for(sofar = 0; sofar < n; sofar += i, off += i, a += i){ if(off < Chunk){ i = n; if(off + i > Chunk) i = Chunk - off; memmove(fp->mem + off, a, i); continue; } if(fp->fd < 0) if(createtmp(fp) < 0) return seterr("can't create temp file"); if(fp->off != off) if(seek(fp->fd, off, 0) < 0){ fp->off = -1; return seterr("can't seek temp file"); } i = write(fp->fd, a, n-sofar); if(i <= 0){ fp->off = -1; return seterr("can't write temp file"); } fp->off = off + i; } if(off > fp->len) fp->len = off; if(off > node->d->length) node->d->length = off; return sofar; } /* * mark a file as dirty */ void filedirty(Node *node) { File *fp; fp = fileget(node); fp->dirty = 1; } /* * mark a file as clean */ void fileclean(Node *node) { if(node->fp) node->fp->dirty = 0; } int fileisdirty(Node *node) { return node->fp && node->fp->dirty; }