concat: Use plain read/write instead of buffered stdio
If we are just copying data from one file to another, we don't need to fill a complete buffer, just read a chunk at a time, and write it to the output.
This commit is contained in:
Michael Forney
committed by
Anselm R Garbe
Anselm R Garbe
parent
9a3b12525b
commit
3276fbea1c
197
tail.c
197
tail.c
@@ -1,80 +1,125 @@
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/* See LICENSE file for copyright and license details. */
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "text.h"
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#include "utf.h"
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#include "util.h"
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static char mode = 'n';
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static void
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dropinit(FILE *fp, const char *str, size_t n)
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static int
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dropinit(int fd, const char *fname, size_t count)
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{
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Rune r;
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char *buf = NULL;
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size_t size = 0, i = 1;
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ssize_t len;
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char buf[BUFSIZ], *p;
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ssize_t n;
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int nr;
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if (mode == 'n') {
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while (i < n && (len = getline(&buf, &size, fp)) > 0)
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if (len > 0 && buf[len - 1] == '\n')
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i++;
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} else {
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while (i < n && efgetrune(&r, fp, str))
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i++;
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if (count < 2)
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goto copy;
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count--; /* numbering starts at 1 */
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while (count && (n = read(fd, buf, sizeof(buf))) > 0) {
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if (mode == 'n') {
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for (p = buf; count && n > 0; p++, n--) {
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if (*p == '\n')
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count--;
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}
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} else {
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for (p = buf; count && n > 0; p += nr, n -= nr, count--) {
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nr = charntorune(&r, p, n);
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if (!nr) {
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/* we don't have a full rune, move
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* remaining data to beginning and read
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* again */
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memmove(buf, p, n);
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break;
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}
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}
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}
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}
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if (count) {
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if (n < 0)
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weprintf("read %s:", fname);
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if (n <= 0)
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return n;
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}
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/* write the rest of the buffer */
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if (writeall(1, p, n) < 0)
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eprintf("write:");
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copy:
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switch (concat(fd, fname, 1, "<stdout>")) {
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case -1: /* read error */
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return -1;
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case -2: /* write error */
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exit(1);
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default:
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return 0;
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}
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free(buf);
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concat(fp, str, stdout, "<stdout>");
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}
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static void
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taketail(FILE *fp, const char *str, size_t n)
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static int
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taketail(int fd, const char *fname, size_t count)
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{
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Rune *r = NULL;
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struct line *ring = NULL;
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size_t i, j, *size = NULL;
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ssize_t len;
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int seenln = 0;
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static char *buf = NULL;
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static size_t size = 0;
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char *p;
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size_t len = 0, left;
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ssize_t n;
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if (!n)
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return;
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if (mode == 'n') {
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ring = ecalloc(n, sizeof(*ring));
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size = ecalloc(n, sizeof(*size));
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for (i = j = 0; (len = getline(&ring[i].data,
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&size[i], fp)) > 0; seenln = 1) {
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ring[i].len = len;
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i = j = (i + 1) % n;
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if (!count)
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return 0;
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for (;;) {
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if (len + BUFSIZ > size) {
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/* make sure we have at least BUFSIZ to read */
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size += 2 * BUFSIZ;
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buf = erealloc(buf, size);
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}
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n = read(fd, buf + len, size - len);
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if (n < 0) {
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weprintf("read %s:", fname);
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return -1;
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}
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if (n == 0)
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break;
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len += n;
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if (mode == 'n') {
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/* ignore the last character; if it is a newline, it
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* ends the last line */
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for (p = buf + len - 2, left = count; p >= buf; p--) {
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if (*p != '\n')
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continue;
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left--;
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if (!left) {
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p++;
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break;
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}
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}
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} else {
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for (p = buf + len - 1, left = count; p >= buf; p--) {
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/* skip utf-8 continuation bytes */
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if ((*p & 0xc0) == 0x80)
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continue;
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left--;
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if (!left)
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break;
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}
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}
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if (p > buf) {
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len -= p - buf;
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memmove(buf, p, len);
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}
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} else {
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r = ecalloc(n, sizeof(*r));
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for (i = j = 0; efgetrune(&r[i], fp, str); )
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i = j = (i + 1) % n;
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}
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if (ferror(fp))
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eprintf("%s: read error:", str);
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do {
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if (seenln && ring && ring[j].data) {
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fwrite(ring[j].data, 1, ring[j].len, stdout);
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free(ring[j].data);
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} else if (r) {
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efputrune(&r[j], stdout, "<stdout>");
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}
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} while ((j = (j + 1) % n) != i);
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free(ring);
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free(size);
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free(r);
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if (writeall(1, buf, len) < 0)
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eprintf("write:");
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return 0;
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}
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static void
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@@ -87,11 +132,11 @@ int
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main(int argc, char *argv[])
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{
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struct stat st1, st2;
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FILE *fp;
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size_t tmpsize, n = 10;
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int fd;
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size_t n = 10;
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int fflag = 0, ret = 0, newline = 0, many = 0;
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char *numstr, *tmp;
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void (*tail)(FILE *, const char *, size_t) = taketail;
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char *numstr;
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int (*tail)(int, const char *, size_t) = taketail;
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ARGBEGIN {
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case 'f':
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@@ -113,17 +158,18 @@ main(int argc, char *argv[])
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usage();
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} ARGEND
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if (!argc)
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tail(stdin, "<stdin>", n);
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else {
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if (!argc) {
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if (tail(0, "<stdin>", n) < 0)
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ret = 1;
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} else {
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if ((many = argc > 1) && fflag)
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usage();
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for (newline = 0; *argv; argc--, argv++) {
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if (!strcmp(*argv, "-")) {
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*argv = "<stdin>";
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fp = stdin;
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} else if (!(fp = fopen(*argv, "r"))) {
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weprintf("fopen %s:", *argv);
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fd = 0;
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} else if ((fd = open(*argv, O_RDONLY)) < 0) {
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weprintf("open %s:", *argv);
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ret = 1;
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continue;
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}
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@@ -134,27 +180,26 @@ main(int argc, char *argv[])
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if (!(S_ISFIFO(st1.st_mode) || S_ISREG(st1.st_mode)))
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fflag = 0;
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newline = 1;
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tail(fp, *argv, n);
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if (tail(fd, *argv, n) < 0) {
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ret = 1;
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fflag = 0;
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}
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if (!fflag) {
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if (fp != stdin && fshut(fp, *argv))
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ret = 1;
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if (fd != 0)
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close(fd);
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continue;
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}
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for (tmp = NULL, tmpsize = 0;;) {
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while (getline(&tmp, &tmpsize, fp) > 0) {
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fputs(tmp, stdout);
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fflush(stdout);
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}
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if (ferror(fp))
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eprintf("readline %s:", *argv);
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clearerr(fp);
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for (;;) {
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if (concat(fd, *argv, 1, "<stdout>") < 0)
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exit(1);
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/* ignore error in case file was removed, we continue
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* tracking the existing open file descriptor */
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if (!stat(*argv, &st2)) {
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if (st2.st_size < st1.st_size) {
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fprintf(stderr, "%s: file truncated\n", *argv);
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rewind(fp);
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if (lseek(fd, SEEK_SET, 0) < 0)
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eprintf("lseek:");
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}
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st1 = st2;
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}
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@@ -163,7 +208,5 @@ main(int argc, char *argv[])
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}
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}
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ret |= fshut(stdin, "<stdin>") | fshut(stdout, "<stdout>");
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return ret;
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}
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