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/*
* minimal, sensible alternatives to echo(1)
*
* necho - print arguments, one per line
* zecho - print arguments, nul-terminated
* qecho - print arguments surrounded in unicode quotation marks
* jecho - print arguments joined together
* secho - print arguments joined with spaces, and a newline
*
* These commands print all arguments as-is, and try to use
* - one syscall per argument for necho, zecho, qecho
* - few writev syscalls for jecho, secho
*
* secho is a POSIX-conforming, but not XSI-conforming implementation of echo(1).
*
* To the extent possible under law, the creator of this work has waived
* all copyright and related or neighboring rights to this work.
* http://creativecommons.org/publicdomain/zero/1.0/
*/
#define _XOPEN_SOURCE 700
#include <sys/uio.h>
#include <errno.h>
#include <limits.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
/* struct iovec[IOV_MAX] should fit on the stack */
#if IOV_MAX > 1024
#define SENSIBLE_IOV_MAX 1024
#else
#define SENSIBLE_IOV_MAX IOV_MAX
#endif
/* like writev(2), but deal with short writes */
ssize_t
safe_writev(int fd, struct iovec *iov, int iovcnt)
{
ssize_t len, wr;
int i;
for (i = 0, len = 0; i < iovcnt; i++)
len += iov[i].iov_len;
while (len > 0) {
if ((wr = writev(fd, iov, iovcnt)) < 0)
return -1;
len -= wr;
if (len <= 0)
return 0;
/* short write, clear emitted prefix of iovec */
for (i = 0; i < iovcnt && wr < (ssize_t)iov[i].iov_len; i++) {
wr -= iov[i].iov_len;
iov[i].iov_base = 0;
iov[i].iov_len = 0;
}
if (i < iovcnt) {
iov[i].iov_base = (char *)iov[i].iov_base + wr;
iov[i].iov_len -= wr;
}
}
return 0;
}
int
main(int argc, char *argv[])
{
int i;
char *style = strrchr(argv[0], '/');
if (style)
style++;
else
style = argv[0];
errno = 0;
if (*style == 'q') {
for (i = 1; i < argc; i++) {
ssize_t len = strlen(argv[i]);
struct iovec iov[] = {
/* U+00BB RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK */
{ "\302\273", 2 },
{ argv[i], len },
/* U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK */
{ "\302\253", 2 },
{ i == argc - 1 ? "\n" : " ", 1 }
};
if (safe_writev(1, iov, 4) < 0)
break;
}
} else if (*style == 'j' || (*style == 's' || *style == 'e')) {
struct iovec iov[SENSIBLE_IOV_MAX];
int j = 0;
i = 1;
if (argc == 1 && *style != 'j')
goto just_nl;
while (i < argc) {
for (j = 0; i < argc && j < SENSIBLE_IOV_MAX - 1; j++) {
iov[j].iov_base = argv[i];
iov[j].iov_len = strlen(argv[i]);
i++;
if (*style != 'j') {
j++;
just_nl:
iov[j].iov_base = i == argc ? "\n" : " ";
iov[j].iov_len = 1;
}
}
if (safe_writev(1, iov, j) < 0)
break;
}
} else { /* default to necho */
for (i = 1; i < argc; i++) {
struct iovec iov[] = {
{ argv[i], strlen(argv[i]) },
{ *style == 'z' ? "\0" : "\n", 1 }
};
if (safe_writev(1, iov, 2) < 0)
break;
}
}
if (errno) {
#ifndef TINY
char *msg = strerror(errno);
struct iovec iov[] = {
{ style, strlen(style) },
{ ": write error: ", 15 },
{ msg, strlen(msg) },
{ "\n", 1 },
};
(void)writev(2, iov, 4);
#endif
return 1;
}
return 0;
}
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