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/* xargs.c - Run command with arguments taken from stdin.
*
* Copyright 2011 Rob Landley <rob@landley.net>
*
* See http://opengroup.org/onlinepubs/9699919799/utilities/xargs.html
*
* TODO: Rich's whitespace objection, env size isn't fixed anymore.
* TODO: -I Insert mode
* TODO: -L Max number of lines of input per command
* TODO: -x Exit if can't fit everything in one command
* TODO: -P NUM Run up to NUM processes at once
USE_XARGS(NEWTOY(xargs, "^E:P#optrn#<1(max-args)s#0[!0E]", TOYFLAG_USR|TOYFLAG_BIN))
config XARGS
bool "xargs"
default y
help
usage: xargs [-0prt] [-s NUM] [-n NUM] [-E STR] COMMAND...
Run command line one or more times, appending arguments from stdin.
If COMMAND exits with 255, don't launch another even if arguments remain.
-0 Each argument is NULL terminated, no whitespace or quote processing
-E Stop at line matching string
-n Max number of arguments per command
-o Open tty for COMMAND's stdin (default /dev/null)
-p Prompt for y/n from tty before running each command
-r Don't run command with empty input (otherwise always run command once)
-s Size in bytes per command line
-t Trace, print command line to stderr
*/
#define FOR_xargs
#include "toys.h"
GLOBALS(
long s, n, P;
char *E;
long entries, bytes;
char delim;
FILE *tty;
)
// If !entry count TT.bytes and TT.entries, stopping at max.
// Otherwise, fill out entry[].
// Returning NULL means need more data.
// Returning char * means hit data limits, start of data left over
// Returning 1 means hit data limits, but consumed all data
// Returning 2 means hit -E STR
static char *handle_entries(char *data, char **entry)
{
if (TT.delim) {
char *save, *ss, *s;
// Chop up whitespace delimited string into args
for (s = data; *s; TT.entries++) {
while (isspace(*s)) s++;
if (TT.n && TT.entries >= TT.n) return *s ? s : (char *)1;
if (!*s) break;
save = ss = s;
// Specifying -s can cause "argument too long" errors.
if (!FLAG(s)) TT.bytes += sizeof(void *)+1;
for (;;) {
if (++TT.bytes >= TT.s) return save;
if (!*s || isspace(*s)) break;
s++;
}
if (TT.E && strstart(&ss, TT.E) && ss == s) return (char *)2;
if (entry) {
entry[TT.entries] = save;
if (*s) *s++ = 0;
}
}
// -0 support
} else {
long bytes = TT.bytes+sizeof(char *)+strlen(data)+1;
if (bytes >= TT.s || (TT.n && TT.entries >= TT.n)) return data;
TT.bytes = bytes;
if (entry) entry[TT.entries] = data;
TT.entries++;
}
return 0;
}
void xargs_main(void)
{
struct double_list *dlist = 0, *dtemp;
int entries, bytes, done = 0, status;
char *data = 0, **out;
pid_t pid = 0;
// POSIX requires that we never hit the ARG_MAX limit, even if we try to
// with -s. POSIX also says we have to reserve 2048 bytes "to guarantee
// that the invoked utility has room to modify its environment variables
// and command line arguments and still be able to invoke another utility",
// though obviously that's not really something you can guarantee.
if (!FLAG(s)) TT.s = sysconf(_SC_ARG_MAX) - environ_bytes() - 4096;
TT.delim = '\n'*!FLAG(0);
// If no optargs, call echo.
if (!toys.optc) {
free(toys.optargs);
*(toys.optargs = xzalloc(2*sizeof(char *)))="echo";
toys.optc = 1;
}
// count entries
for (entries = 0, bytes = -1; entries < toys.optc; entries++)
bytes += strlen(toys.optargs[entries])+1+sizeof(char *)*!FLAG(s);
if (bytes >= TT.s) error_exit("argument too long");
// Loop through exec chunks.
while (data || !done) {
TT.entries = 0;
TT.bytes = bytes;
// Loop reading input
for (;;) {
// Read line
if (!data) {
size_t l = 0;
if (getdelim(&data, &l, TT.delim, stdin)<0) {
data = 0;
done++;
break;
}
}
dlist_add(&dlist, data);
// Count data used
if (!(data = handle_entries(data, 0))) continue;
if (data == (char *)2) done++;
if ((unsigned long)data <= 2) data = 0;
else data = xstrdup(data);
break;
}
if (!TT.entries) {
if (data) error_exit("argument too long");
else if (pid) return;
else if (FLAG(r)) continue;
}
// Fill out command line to exec
out = xzalloc((entries+TT.entries+1)*sizeof(char *));
memcpy(out, toys.optargs, entries*sizeof(char *));
TT.entries = 0;
TT.bytes = bytes;
if (dlist) dlist->prev->next = 0;
for (dtemp = dlist; dtemp; dtemp = dtemp->next)
handle_entries(dtemp->data, out+entries);
if (FLAG(p) || FLAG(t)) {
int i;
for (i = 0; out[i]; ++i) fprintf(stderr, "%s ", out[i]);
if (FLAG(p)) {
fprintf(stderr, "?");
if (!TT.tty) TT.tty = xfopen("/dev/tty", "re");
if (!fyesno(TT.tty, 0)) goto skip;
} else fprintf(stderr, "\n");
}
if (!(pid = XVFORK())) {
close(0);
xopen_stdio(FLAG(o) ? "/dev/tty" : "/dev/null", O_RDONLY);
xexec(out);
}
waitpid(pid, &status, 0);
// xargs is yet another weird collection of exit value special cases,
// different from all the others.
if (WIFEXITED(status)) {
if (WEXITSTATUS(status) == 126 || WEXITSTATUS(status) == 127) {
toys.exitval = WEXITSTATUS(status);
return;
} else if (WEXITSTATUS(status) >= 1 && WEXITSTATUS(status) <= 125) {
toys.exitval = 123;
} else if (WEXITSTATUS(status) == 255) {
error_msg("%s: exited with status 255; aborting", out[0]);
toys.exitval = 124;
return;
}
} else toys.exitval = 127;
// Abritrary number of execs, can't just leak memory each time...
skip:
llist_traverse(dlist, llist_free_double);
dlist = 0;
free(out);
}
if (TT.tty) fclose(TT.tty);
}
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