75 lines
1.7 KiB
C
75 lines
1.7 KiB
C
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/* Eliminate teeny little writes. patch submitted by
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Rob Ross <rbross@parl.ces.clemson.edu> --Monty 19991008 */
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#include <stdio.h>
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#define OUTBUFSZ 32*1024
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#include "utils.h"
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extern long blocking_write(int outf, char *buffer, long num);
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/* GLOBALS FOR BUFFERING CALLS */
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static int bw_fd = -1;
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static long bw_pos = 0;
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static char bw_outbuf[OUTBUFSZ];
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/* buffering_write() - buffers data to a specified size before writing.
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*
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* Restrictions:
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* - MUST CALL BUFFERING_CLOSE() WHEN FINISHED!!!
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*
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*/
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long buffering_write(int fd, char *buffer, long num)
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{
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if (fd != bw_fd) {
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/* clean up after buffering for some other file */
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if (bw_fd >= 0 && bw_pos > 0) {
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if (blocking_write(bw_fd, bw_outbuf, bw_pos)) {
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perror("write (in buffering_write, flushing)");
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}
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}
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bw_fd = fd;
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bw_pos = 0;
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}
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if (bw_pos + num > OUTBUFSZ) {
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/* fill our buffer first, then write, then modify buffer and num */
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memcpy(&bw_outbuf[bw_pos], buffer, OUTBUFSZ - bw_pos);
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if (blocking_write(fd, bw_outbuf, OUTBUFSZ)) {
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perror("write (in buffering_write, full buffer)");
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return(-1);
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}
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num -= (OUTBUFSZ - bw_pos);
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buffer += (OUTBUFSZ - bw_pos);
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bw_pos = 0;
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}
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/* save data */
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if(buffer && num)
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memcpy(&bw_outbuf[bw_pos], buffer, num);
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bw_pos += num;
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return(0);
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}
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/* buffering_close() - writes out remaining buffered data before closing
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* file.
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*
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*/
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int buffering_close(int fd)
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{
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if (fd == bw_fd && bw_pos > 0) {
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/* write out remaining data and clean up */
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if (blocking_write(fd, bw_outbuf, bw_pos)) {
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perror("write (in buffering_close)");
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}
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bw_fd = -1;
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bw_pos = 0;
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}
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return(close(fd));
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}
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