commit 9a3b12525bd3a2627f5a45c7afe00737a041bb5b
parent 5cb3a1eba1b7568b3c6c32c1e6808de24b38a757
Author: Michael Forney <mforney@mforney.org>
Date: Sun, 1 Jan 2017 17:00:33 -0800
Don't use buffered IO (fread) when not appropriate
fread reads the entire requested size (BUFSIZ), which causes tools to
block if only small amounts of data are available at a time. At best,
this causes unnecessary copies and inefficiency, at worst, tools like
tee and cat are almost unusable in some cases since they only display
large chunks of data at a time.
Diffstat:
| M | cksum.c | | | 31 | +++++++++++++++++-------------- |
| M | crypt.h | | | 2 | +- |
| M | libutil/crypt.c | | | 37 | +++++++++++++++++++------------------ |
| M | od.c | | | 43 | +++++++++++++++++++++++++++---------------- |
| M | tee.c | | | 39 | +++++++++++++++++++-------------------- |
5 files changed, 83 insertions(+), 69 deletions(-)
diff --git a/cksum.c b/cksum.c
@@ -1,7 +1,9 @@
/* See LICENSE file for copyright and license details. */
+#include <fcntl.h>
#include <inttypes.h>
#include <stdio.h>
#include <string.h>
+#include <unistd.h>
#include "util.h"
@@ -61,19 +63,20 @@ static const unsigned long crctab[] = { 0x00000000,
};
static void
-cksum(FILE *fp, const char *s)
+cksum(int fd, const char *s)
{
- size_t len = 0, i, n;
+ ssize_t n;
+ size_t len = 0, i;
uint32_t ck = 0;
unsigned char buf[BUFSIZ];
- while ((n = fread(buf, 1, sizeof(buf), fp))) {
+ while ((n = read(fd, buf, sizeof(buf))) > 0) {
for (i = 0; i < n; i++)
ck = (ck << 8) ^ crctab[(ck >> 24) ^ buf[i]];
len += n;
}
- if (ferror(fp)) {
- weprintf("fread %s:", s ? s : "<stdin>");
+ if (n < 0) {
+ weprintf("read %s:", s ? s : "<stdin>");
ret = 1;
return;
}
@@ -92,29 +95,29 @@ cksum(FILE *fp, const char *s)
int
main(int argc, char *argv[])
{
- FILE *fp;
+ int fd;
argv0 = argv[0], argc--, argv++;
if (!argc) {
- cksum(stdin, NULL);
+ cksum(0, NULL);
} else {
for (; *argv; argc--, argv++) {
if (!strcmp(*argv, "-")) {
*argv = "<stdin>";
- fp = stdin;
- } else if (!(fp = fopen(*argv, "r"))) {
- weprintf("fopen %s:", *argv);
+ fd = 0;
+ } else if ((fd = open(*argv, O_RDONLY)) < 0) {
+ weprintf("open %s:", *argv);
ret = 1;
continue;
}
- cksum(fp, *argv);
- if (fp != stdin && fshut(fp, *argv))
- ret = 1;
+ cksum(fd, *argv);
+ if (fd != 0)
+ close(fd);
}
}
- ret |= fshut(stdin, "<stdin>") | fshut(stdout, "<stdout>");
+ ret |= fshut(stdout, "<stdout>");
return ret;
}
diff --git a/crypt.h b/crypt.h
@@ -8,5 +8,5 @@ struct crypt_ops {
int cryptcheck(int, char **, struct crypt_ops *, uint8_t *, size_t);
int cryptmain(int, char **, struct crypt_ops *, uint8_t *, size_t);
-int cryptsum(struct crypt_ops *, FILE *, const char *, uint8_t *);
+int cryptsum(struct crypt_ops *, int, const char *, uint8_t *);
void mdprint(const uint8_t *, const char *, size_t);
diff --git a/libutil/crypt.c b/libutil/crypt.c
@@ -1,8 +1,10 @@
/* See LICENSE file for copyright and license details. */
+#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <unistd.h>
#include "../crypt.h"
#include "../text.h"
@@ -41,7 +43,7 @@ static void
mdchecklist(FILE *listfp, struct crypt_ops *ops, uint8_t *md, size_t sz,
int *formatsucks, int *noread, int *nonmatch)
{
- FILE *fp;
+ int fd;
size_t bufsiz = 0;
int r;
char *line = NULL, *file, *p;
@@ -59,12 +61,12 @@ mdchecklist(FILE *listfp, struct crypt_ops *ops, uint8_t *md, size_t sz,
file += 2;
for (p = file; *p && *p != '\n' && *p != '\r'; p++); /* strip newline */
*p = '\0';
- if (!(fp = fopen(file, "r"))) {
- weprintf("fopen %s:", file);
+ if ((fd = open(file, O_RDONLY)) < 0) {
+ weprintf("open %s:", file);
(*noread)++;
continue;
}
- if (cryptsum(ops, fp, file, md)) {
+ if (cryptsum(ops, fd, file, md)) {
(*noread)++;
continue;
}
@@ -77,7 +79,7 @@ mdchecklist(FILE *listfp, struct crypt_ops *ops, uint8_t *md, size_t sz,
} else {
(*formatsucks)++;
}
- fclose(fp);
+ close(fd);
}
free(line);
}
@@ -124,11 +126,11 @@ cryptcheck(int argc, char *argv[], struct crypt_ops *ops, uint8_t *md, size_t sz
int
cryptmain(int argc, char *argv[], struct crypt_ops *ops, uint8_t *md, size_t sz)
{
- FILE *fp;
+ int fd;
int ret = 0;
if (argc == 0) {
- if (cryptsum(ops, stdin, "<stdin>", md))
+ if (cryptsum(ops, 0, "<stdin>", md))
ret = 1;
else
mdprint(md, "<stdin>", sz);
@@ -136,18 +138,18 @@ cryptmain(int argc, char *argv[], struct crypt_ops *ops, uint8_t *md, size_t sz)
for (; *argv; argc--, argv++) {
if ((*argv)[0] == '-' && !(*argv)[1]) {
*argv = "<stdin>";
- fp = stdin;
- } else if (!(fp = fopen(*argv, "r"))) {
- weprintf("fopen %s:", *argv);
+ fd = 0;
+ } else if ((fd = open(*argv, O_RDONLY)) < 0) {
+ weprintf("open %s:", *argv);
ret = 1;
continue;
}
- if (cryptsum(ops, fp, *argv, md))
+ if (cryptsum(ops, fd, *argv, md))
ret = 1;
else
mdprint(md, *argv, sz);
- if (fp != stdin && fshut(fp, *argv))
- ret = 1;
+ if (fd != 0)
+ close(fd);
}
}
@@ -155,16 +157,15 @@ cryptmain(int argc, char *argv[], struct crypt_ops *ops, uint8_t *md, size_t sz)
}
int
-cryptsum(struct crypt_ops *ops, FILE *fp, const char *f,
- uint8_t *md)
+cryptsum(struct crypt_ops *ops, int fd, const char *f, uint8_t *md)
{
uint8_t buf[BUFSIZ];
- size_t n;
+ ssize_t n;
ops->init(ops->s);
- while ((n = fread(buf, 1, sizeof(buf), fp)) > 0)
+ while ((n = read(fd, buf, sizeof(buf))) > 0)
ops->update(ops->s, buf, n);
- if (ferror(fp)) {
+ if (n < 0) {
weprintf("%s: read error:", f);
return 1;
}
diff --git a/od.c b/od.c
@@ -1,8 +1,10 @@
/* See LICENSE file for copyright and license details. */
+#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <unistd.h>
#include "queue.h"
#include "util.h"
@@ -124,20 +126,23 @@ once:
}
}
-static void
-od(FILE *fp, char *fname, int last)
+static int
+od(int fd, char *fname, int last)
{
static unsigned char *line;
static size_t lineoff;
static off_t addr;
unsigned char buf[BUFSIZ];
- size_t i, n, size = sizeof(buf);
+ size_t i, size = sizeof(buf);
+ ssize_t n;
while (skip - addr > 0) {
- n = fread(buf, 1, MIN(skip - addr, sizeof(buf)), fp);
+ n = read(fd, buf, MIN(skip - addr, sizeof(buf)));
+ if (n < 0)
+ weprintf("read %s:", fname);
+ if (n <= 0)
+ return n;
addr += n;
- if (feof(fp) || ferror(fp))
- return;
}
if (!line)
line = emalloc(linelen);
@@ -145,7 +150,7 @@ od(FILE *fp, char *fname, int last)
for (;;) {
if (max >= 0)
size = MIN(max - (addr - skip), size);
- if (!(n = fread(buf, 1, size, fp)))
+ if ((n = read(fd, buf, size)) <= 0)
break;
for (i = 0; i < n; i++, addr++) {
line[lineoff++] = buf[i];
@@ -155,10 +160,15 @@ od(FILE *fp, char *fname, int last)
}
}
}
+ if (n < 0) {
+ weprintf("read %s:", fname);
+ return n;
+ }
if (lineoff && last)
printline(line, lineoff, addr - lineoff);
if (last)
printline((unsigned char *)"", 0, addr);
+ return 0;
}
static int
@@ -196,7 +206,7 @@ usage(void)
int
main(int argc, char *argv[])
{
- FILE *fp;
+ int fd;
struct type *t;
int ret = 0, len;
char *s;
@@ -293,25 +303,26 @@ main(int argc, char *argv[])
linelen *= 2;
if (!argc) {
- od(stdin, "<stdin>", 1);
+ if (od(0, "<stdin>", 1) < 0)
+ ret = 1;
} else {
for (; *argv; argc--, argv++) {
if (!strcmp(*argv, "-")) {
*argv = "<stdin>";
- fp = stdin;
- } else if (!(fp = fopen(*argv, "r"))) {
- weprintf("fopen %s:", *argv);
+ fd = 0;
+ } else if ((fd = open(*argv, O_RDONLY)) < 0) {
+ weprintf("open %s:", *argv);
ret = 1;
continue;
}
- od(fp, *argv, (!*(argv + 1)));
- if (fp != stdin && fshut(fp, *argv))
+ if (od(fd, *argv, (!*(argv + 1))) < 0)
ret = 1;
+ if (fd != 0)
+ close(fd);
}
}
- ret |= fshut(stdin, "<stdin>") | fshut(stdout, "<stdout>") |
- fshut(stderr, "<stderr>");
+ ret |= fshut(stdout, "<stdout>") | fshut(stderr, "<stderr>");
return ret;
}
diff --git a/tee.c b/tee.c
@@ -1,6 +1,7 @@
/* See LICENSE file for copyright and license details. */
+#include <fcntl.h>
#include <signal.h>
-#include <stdio.h>
+#include <unistd.h>
#include "util.h"
@@ -13,14 +14,15 @@ usage(void)
int
main(int argc, char *argv[])
{
- FILE **fps = NULL;
- size_t i, n, nfps;
- int ret = 0, aflag = 0, iflag = 0;
+ int *fds = NULL;
+ size_t i, nfds;
+ ssize_t n;
+ int ret = 0, aflag = O_TRUNC, iflag = 0;
char buf[BUFSIZ];
ARGBEGIN {
case 'a':
- aflag = 1;
+ aflag = O_APPEND;
break;
case 'i':
iflag = 1;
@@ -31,31 +33,28 @@ main(int argc, char *argv[])
if (iflag && signal(SIGINT, SIG_IGN) == SIG_ERR)
eprintf("signal:");
- nfps = argc + 1;
- fps = ecalloc(nfps, sizeof(*fps));
+ nfds = argc + 1;
+ fds = ecalloc(nfds, sizeof(*fds));
for (i = 0; i < argc; i++) {
- if (!(fps[i] = fopen(argv[i], aflag ? "a" : "w"))) {
- weprintf("fopen %s:", argv[i]);
+ if ((fds[i] = open(argv[i], O_WRONLY|O_CREAT|aflag, 0666)) < 0) {
+ weprintf("open %s:", argv[i]);
ret = 1;
}
}
- fps[i] = stdout;
+ fds[i] = 1;
- while ((n = fread(buf, 1, sizeof(buf), stdin))) {
- for (i = 0; i < nfps; i++) {
- if (fps[i] && fwrite(buf, 1, n, fps[i]) != n) {
- fshut(fps[i], (i != argc) ? argv[i] : "<stdout>");
- fps[i] = NULL;
+ while ((n = read(0, buf, sizeof(buf))) > 0) {
+ for (i = 0; i < nfds; i++) {
+ if (fds[i] >= 0 && writeall(fds[i], buf, n) < 0) {
+ weprintf("write %s:", (i != argc) ? argv[i] : "<stdout>");
+ fds[i] = -1;
ret = 1;
}
}
}
-
- ret |= fshut(stdin, "<stdin>");
- for (i = 0; i < nfps; i++)
- if (fps[i])
- ret |= fshut(fps[i], (i != argc) ? argv[i] : "<stdout>");
+ if (n < 0)
+ eprintf("read <stdin>:");
return ret;
}
