bio: add support for custom I/O handler via Biofn
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@ -33,6 +33,7 @@ struct Biobufhdr
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uchar* ebuf; /* pointer to end of buffer */
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uchar* gbuf; /* pointer to good data in buf */
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void (*errorf)(char *); /* called on error if not nil */
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int (*iof)(Biobufhdr*, void *, long); /* called to do i/o */
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};
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struct Biobuf
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@ -74,6 +75,7 @@ int Bungetrune(Biobufhdr*);
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long Bwrite(Biobufhdr*, void*, long);
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void Blethal(Biobufhdr*, void(*)(char*));
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void Berror(Biobufhdr*, char*, ...);
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void Biofn(Biobufhdr*, int(*)(Biobufhdr*, void*, long));
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#pragma varargck argpos Bprint 2
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#pragma varargck argpos Berror 2
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@ -84,6 +84,9 @@ int Bbuffered(Biobufhdr *bp)
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.B
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void Blethal(Biobufhdr *bp, void (*errorf)(char *))
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.PP
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.B
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void Biofn(Biobufhdr *bp, int (*iof)(Biohdr *, void *, long))
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.PP
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.SH DESCRIPTION
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These routines implement fast buffered I/O.
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I/O on different file descriptors is independent.
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@ -338,6 +341,18 @@ to be called in case of an error happening on read/write.
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An argument of
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.B nil
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will have the program terminated in case of error.
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.PP
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If
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.I Biofn
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is called with a non-nil
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.I iof
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function, then that function is called for I/O in lieu of
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.IR read (2)
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and
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.IR write (2).
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A nil argument for
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.I iof
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restores normal behaviour.
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.SH SOURCE
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.B /sys/src/libbio
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.SH SEE ALSO
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@ -12,7 +12,7 @@ Bflush(Biobufhdr *bp)
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n = bp->bsize+bp->ocount;
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if(n == 0)
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return 0;
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c = write(bp->fid, bp->bbuf, n);
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c = bp->iof(bp, bp->bbuf, n);
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if(n == c) {
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bp->offset += n;
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bp->ocount = -bp->bsize;
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@ -24,7 +24,7 @@ loop:
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* buffer to allow that many ungets.
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*/
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memmove(bp->bbuf-Bungetsize, bp->ebuf-Bungetsize, Bungetsize);
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i = read(bp->fid, bp->bbuf, bp->bsize);
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i = bp->iof(bp, bp->bbuf, bp->bsize);
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bp->gbuf = bp->bbuf;
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if(i <= 0) {
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bp->state = Bracteof;
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@ -50,6 +50,18 @@ install(Biobufhdr *bp)
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}
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}
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static int
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bioread(Biobufhdr *bp, void *v, long n)
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{
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return read(bp->fid, v, n);
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}
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static int
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biowrite(Biobufhdr *bp, void *v, long n)
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{
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return write(bp->fid, v, n);
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}
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int
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Binits(Biobufhdr *bp, int f, int mode, uchar *p, int size)
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{
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@ -64,12 +76,14 @@ Binits(Biobufhdr *bp, int f, int mode, uchar *p, int size)
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case OREAD:
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bp->state = Bractive;
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bp->ocount = 0;
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bp->iof = bioread;
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break;
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case OWRITE:
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install(bp);
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bp->state = Bwactive;
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bp->ocount = -size;
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bp->iof = biowrite;
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break;
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}
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bp->bbuf = p;
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@ -154,3 +168,15 @@ Bterm(Biobufhdr *bp)
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/* otherwise opened with Binit(s) */
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return r;
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}
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void
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Biofn(Biobufhdr *bp, int (*f)(Biobufhdr *, void *, long))
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{
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if(f == nil)
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if(bp->state == Bwactive)
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bp->iof = biowrite;
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else
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bp->iof = bioread;
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else
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bp->iof = f;
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}
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@ -46,7 +46,7 @@ Brdline(Biobufhdr *bp, int delim)
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*/
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ip = (char*)bp->bbuf + i;
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while(i < bp->bsize) {
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j = read(bp->fid, ip, bp->bsize-i);
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j = bp->iof(bp, ip, bp->bsize-i);
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if(j < 0)
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Berror(bp, "read error: %r");
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if(j <= 0) {
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@ -69,7 +69,7 @@ Brdstr(Biobufhdr *bp, int delim, int nulldelim)
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for(;;){
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ip = (char*)bp->bbuf + i;
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while(i < bp->bsize) {
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j = read(bp->fid, ip, bp->bsize-i);
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j = bp->iof(bp, ip, bp->bsize-i);
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if(j < 0)
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Berror(bp, "read error: %r");
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if(j <= 0 && i == 0)
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@ -20,7 +20,7 @@ Bread(Biobufhdr *bp, void *ap, long count)
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if(n == 0) {
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if(bp->state != Bractive)
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break;
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i = read(bp->fid, bp->bbuf, bp->bsize);
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i = bp->iof(bp, bp->bbuf, bp->bsize);
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if(i <= 0) {
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bp->state = Bracteof;
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if(i < 0) {
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@ -21,7 +21,7 @@ Bwrite(Biobufhdr *bp, void *ap, long count)
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if(n == 0) {
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if(bp->state != Bwactive)
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return Beof;
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i = write(bp->fid, bp->bbuf, bp->bsize);
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i = bp->iof(bp, bp->bbuf, bp->bsize);
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if(i != bp->bsize) {
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errstr(errbuf, sizeof errbuf);
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if(strstr(errbuf, "interrupt") == nil) {
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