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.
---
 cksum.c         | 31 +++++++++++++++++--------------
 crypt.h         |  2 +-
 libutil/crypt.c | 37 +++++++++++++++++++------------------
 od.c            | 43 +++++++++++++++++++++++++++----------------
 tee.c           | 39 +++++++++++++++++++--------------------
 5 files changed, 83 insertions(+), 69 deletions(-)

diff --git a/cksum.c b/cksum.c
index 570ca81..b53ec17 100644
--- 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
index e0cc08d..2fd2932 100644
--- 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
index 6991c39..e285614 100644
--- 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
index 27a7104..e5dde83 100644
--- 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
index 35e3db5..eac106c 100644
--- 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;
 }
-- 
2.10.2


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