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76 lines
1.5 KiB
76 lines
1.5 KiB
2 months ago
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/*
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* UCW Library -- Fast Buffered Input on Limited File Descriptors
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*
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* (c) 2003--2004 Martin Mares <mj@ucw.cz>
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*
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* This software may be freely distributed and used according to the terms
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* of the GNU Lesser General Public License.
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*/
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#include <ucw/lib.h>
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#include <ucw/fastbuf.h>
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#include <unistd.h>
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struct fb_limfd {
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struct fastbuf fb;
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int fd; /* File descriptor */
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int limit;
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};
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#define FB_LIMFD(f) ((struct fb_limfd *)(f))
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#define FB_BUFFER(f) (byte *)(FB_LIMFD(f) + 1)
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static int
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bfl_refill(struct fastbuf *f)
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{
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f->bptr = f->buffer = FB_BUFFER(f);
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int max = MIN(FB_LIMFD(f)->limit - f->pos, f->bufend - f->buffer);
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int l = read(FB_LIMFD(f)->fd, f->buffer, max);
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if (l < 0)
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bthrow(f, "read", "Error reading %s: %m", f->name);
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f->bstop = f->buffer + l;
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f->pos += l;
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return l;
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}
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static void
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bfl_close(struct fastbuf *f)
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{
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xfree(f);
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}
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struct fastbuf *
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bopen_limited_fd(int fd, uint buflen, uint limit)
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{
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struct fb_limfd *F = xmalloc(sizeof(struct fb_limfd) + buflen);
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struct fastbuf *f = &F->fb;
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bzero(F, sizeof(*F));
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f->buffer = (char *)(F+1);
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f->bptr = f->bstop = f->buffer;
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f->bufend = f->buffer + buflen;
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f->name = "limited-fd";
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F->fd = fd;
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F->limit = limit;
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f->refill = bfl_refill;
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f->close = bfl_close;
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f->can_overwrite_buffer = 2;
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return f;
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}
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#ifdef TEST
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int main(int UNUSED argc, char UNUSED **argv)
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{
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struct fastbuf *f = bopen_limited_fd(0, 3, 13);
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struct fastbuf *o = bfdopen_shared(1, 16);
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int c;
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while ((c = bgetc(f)) >= 0)
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bputc(o, c);
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bclose(o);
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bclose(f);
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return 0;
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}
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#endif
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