hush/findutils/xargs.c
Denys Vlasenko 7cfe6ea99e xargs: support --no-run-if-empty (synonym to -r)
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2011-03-03 09:51:57 +01:00

567 lines
14 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini xargs implementation for busybox
*
* (C) 2002,2003 by Vladimir Oleynik <dzo@simtreas.ru>
*
* Special thanks
* - Mark Whitley and Glenn McGrath for stimulus to rewrite :)
* - Mike Rendell <michael@cs.mun.ca>
* and David MacKenzie <djm@gnu.ai.mit.edu>.
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*
* xargs is described in the Single Unix Specification v3 at
* http://www.opengroup.org/onlinepubs/007904975/utilities/xargs.html
*/
//config:config XARGS
//config: bool "xargs"
//config: default y
//config: help
//config: xargs is used to execute a specified command for
//config: every item from standard input.
//config:
//config:config FEATURE_XARGS_SUPPORT_CONFIRMATION
//config: bool "Enable -p: prompt and confirmation"
//config: default y
//config: depends on XARGS
//config: help
//config: Support -p: prompt the user whether to run each command
//config: line and read a line from the terminal.
//config:
//config:config FEATURE_XARGS_SUPPORT_QUOTES
//config: bool "Enable single and double quotes and backslash"
//config: default y
//config: depends on XARGS
//config: help
//config: Support quoting in the input.
//config:
//config:config FEATURE_XARGS_SUPPORT_TERMOPT
//config: bool "Enable -x: exit if -s or -n is exceeded"
//config: default y
//config: depends on XARGS
//config: help
//config: Support -x: exit if the command size (see the -s or -n option)
//config: is exceeded.
//config:
//config:config FEATURE_XARGS_SUPPORT_ZERO_TERM
//config: bool "Enable -0: NUL-terminated input"
//config: default y
//config: depends on XARGS
//config: help
//config: Support -0: input items are terminated by a NUL character
//config: instead of whitespace, and the quotes and backslash
//config: are not special.
//applet:IF_XARGS(APPLET_NOEXEC(xargs, xargs, BB_DIR_USR_BIN, BB_SUID_DROP, xargs))
//kbuild:lib-$(CONFIG_XARGS) += xargs.o
#include "libbb.h"
/* This is a NOEXEC applet. Be very careful! */
//#define dbg_msg(...) bb_error_msg(__VA_ARGS__)
#define dbg_msg(...) ((void)0)
#ifdef TEST
# ifndef ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
# define ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION 1
# endif
# ifndef ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
# define ENABLE_FEATURE_XARGS_SUPPORT_QUOTES 1
# endif
# ifndef ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
# define ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT 1
# endif
# ifndef ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
# define ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM 1
# endif
#endif
struct globals {
char **args;
const char *eof_str;
int idx;
} FIX_ALIASING;
#define G (*(struct globals*)&bb_common_bufsiz1)
#define INIT_G() do { \
G.eof_str = NULL; /* need to clear by hand because we are NOEXEC applet */ \
} while (0)
/*
* This function has special algorithm.
* Don't use fork and include to main!
*/
static int xargs_exec(void)
{
int status;
status = spawn_and_wait(G.args);
if (status < 0) {
bb_simple_perror_msg(G.args[0]);
return errno == ENOENT ? 127 : 126;
}
if (status == 255) {
bb_error_msg("%s: exited with status 255; aborting", G.args[0]);
return 124;
}
if (status >= 0x180) {
bb_error_msg("%s: terminated by signal %d",
G.args[0], status - 0x180);
return 125;
}
if (status)
return 123;
return 0;
}
/* In POSIX/C locale isspace is only these chars: "\t\n\v\f\r" and space.
* "\t\n\v\f\r" happen to have ASCII codes 9,10,11,12,13.
*/
#define ISSPACE(a) ({ unsigned char xargs__isspace = (a) - 9; xargs__isspace == (' ' - 9) || xargs__isspace <= (13 - 9); })
static void store_param(char *s)
{
/* Grow by 256 elements at once */
if (!(G.idx & 0xff)) { /* G.idx == N*256 */
/* Enlarge, make G.args[(N+1)*256 - 1] last valid idx */
G.args = xrealloc(G.args, sizeof(G.args[0]) * (G.idx + 0x100));
}
G.args[G.idx++] = s;
}
/* process[0]_stdin:
* Read characters into buf[n_max_chars+1], and when parameter delimiter
* is seen, store the address of a new parameter to args[].
* If reading discovers that last chars do not form the complete
* parameter, the pointer to the first such "tail character" is returned.
* (buf has extra byte at the end to accomodate terminating NUL
* of "tail characters" string).
* Otherwise, the returned pointer points to NUL byte.
* On entry, buf[] may contain some "seed chars" which are to become
* the beginning of the first parameter.
*/
#if ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
static char* FAST_FUNC process_stdin(int n_max_chars, int n_max_arg, char *buf)
{
#define NORM 0
#define QUOTE 1
#define BACKSLASH 2
#define SPACE 4
char q = '\0'; /* quote char */
char state = NORM;
char *s = buf; /* start of the word */
char *p = s + strlen(buf); /* end of the word */
buf += n_max_chars; /* past buffer's end */
/* "goto ret" is used instead of "break" to make control flow
* more obvious: */
while (1) {
int c = getchar();
if (c == EOF) {
if (p != s)
goto close_word;
goto ret;
}
if (state == BACKSLASH) {
state = NORM;
goto set;
}
if (state == QUOTE) {
if (c != q)
goto set;
q = '\0';
state = NORM;
} else { /* if (state == NORM) */
if (ISSPACE(c)) {
if (p != s) {
close_word:
state = SPACE;
c = '\0';
goto set;
}
} else {
if (c == '\\') {
state = BACKSLASH;
} else if (c == '\'' || c == '"') {
q = c;
state = QUOTE;
} else {
set:
*p++ = c;
}
}
}
if (state == SPACE) { /* word's delimiter or EOF detected */
if (q) {
bb_error_msg_and_die("unmatched %s quote",
q == '\'' ? "single" : "double");
}
/* A full word is loaded */
if (G.eof_str) {
if (strcmp(s, G.eof_str) == 0) {
while (getchar() != EOF)
continue;
p = s;
goto ret;
}
}
store_param(s);
dbg_msg("args[]:'%s'", s);
s = p;
n_max_arg--;
if (n_max_arg == 0) {
goto ret;
}
state = NORM;
}
if (p == buf) {
goto ret;
}
}
ret:
*p = '\0';
/* store_param(NULL) - caller will do it */
dbg_msg("return:'%s'", s);
return s;
}
#else
/* The variant does not support single quotes, double quotes or backslash */
static char* FAST_FUNC process_stdin(int n_max_chars, int n_max_arg, char *buf)
{
char *s = buf; /* start of the word */
char *p = s + strlen(buf); /* end of the word */
buf += n_max_chars; /* past buffer's end */
while (1) {
int c = getchar();
if (c == EOF) {
if (p == s)
goto ret;
}
if (c == EOF || ISSPACE(c)) {
if (p == s)
continue;
c = EOF;
}
*p++ = (c == EOF ? '\0' : c);
if (c == EOF) { /* word's delimiter or EOF detected */
/* A full word is loaded */
if (G.eof_str) {
if (strcmp(s, G.eof_str) == 0) {
while (getchar() != EOF)
continue;
p = s;
goto ret;
}
}
store_param(s);
dbg_msg("args[]:'%s'", s);
s = p;
n_max_arg--;
if (n_max_arg == 0) {
goto ret;
}
}
if (p == buf) {
goto ret;
}
}
ret:
*p = '\0';
/* store_param(NULL) - caller will do it */
dbg_msg("return:'%s'", s);
return s;
}
#endif /* FEATURE_XARGS_SUPPORT_QUOTES */
#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
static char* FAST_FUNC process0_stdin(int n_max_chars, int n_max_arg, char *buf)
{
char *s = buf; /* start of the word */
char *p = s + strlen(buf); /* end of the word */
buf += n_max_chars; /* past buffer's end */
while (1) {
int c = getchar();
if (c == EOF) {
if (p == s)
goto ret;
c = '\0';
}
*p++ = c;
if (c == '\0') { /* word's delimiter or EOF detected */
/* A full word is loaded */
store_param(s);
dbg_msg("args[]:'%s'", s);
s = p;
n_max_arg--;
if (n_max_arg == 0) {
goto ret;
}
}
if (p == buf) {
goto ret;
}
}
ret:
*p = '\0';
/* store_param(NULL) - caller will do it */
dbg_msg("return:'%s'", s);
return s;
}
#endif /* FEATURE_XARGS_SUPPORT_ZERO_TERM */
#if ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
/* Prompt the user for a response, and
if the user responds affirmatively, return true;
otherwise, return false. Uses "/dev/tty", not stdin. */
static int xargs_ask_confirmation(void)
{
FILE *tty_stream;
int c, savec;
tty_stream = xfopen_for_read(CURRENT_TTY);
fputs(" ?...", stderr);
fflush_all();
c = savec = getc(tty_stream);
while (c != EOF && c != '\n')
c = getc(tty_stream);
fclose(tty_stream);
return (savec == 'y' || savec == 'Y');
}
#else
# define xargs_ask_confirmation() 1
#endif
//usage:#define xargs_trivial_usage
//usage: "[OPTIONS] [PROG ARGS]"
//usage:#define xargs_full_usage "\n\n"
//usage: "Run PROG on every item given by stdin\n"
//usage: "\nOptions:"
//usage: IF_FEATURE_XARGS_SUPPORT_CONFIRMATION(
//usage: "\n -p Ask user whether to run each command"
//usage: )
//usage: "\n -r Don't run command if input is empty"
//usage: IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(
//usage: "\n -0 Input is separated by NUL characters"
//usage: )
//usage: "\n -t Print the command on stderr before execution"
//usage: "\n -e[STR] STR stops input processing"
//usage: "\n -n N Pass no more than N args to PROG"
//usage: "\n -s N Pass command line of no more than N bytes"
//usage: IF_FEATURE_XARGS_SUPPORT_TERMOPT(
//usage: "\n -x Exit if size is exceeded"
//usage: )
//usage:#define xargs_example_usage
//usage: "$ ls | xargs gzip\n"
//usage: "$ find . -name '*.c' -print | xargs rm\n"
/* Correct regardless of combination of CONFIG_xxx */
enum {
OPTBIT_VERBOSE = 0,
OPTBIT_NO_EMPTY,
OPTBIT_UPTO_NUMBER,
OPTBIT_UPTO_SIZE,
OPTBIT_EOF_STRING,
OPTBIT_EOF_STRING1,
IF_FEATURE_XARGS_SUPPORT_CONFIRMATION(OPTBIT_INTERACTIVE,)
IF_FEATURE_XARGS_SUPPORT_TERMOPT( OPTBIT_TERMINATE ,)
IF_FEATURE_XARGS_SUPPORT_ZERO_TERM( OPTBIT_ZEROTERM ,)
OPT_VERBOSE = 1 << OPTBIT_VERBOSE ,
OPT_NO_EMPTY = 1 << OPTBIT_NO_EMPTY ,
OPT_UPTO_NUMBER = 1 << OPTBIT_UPTO_NUMBER,
OPT_UPTO_SIZE = 1 << OPTBIT_UPTO_SIZE ,
OPT_EOF_STRING = 1 << OPTBIT_EOF_STRING , /* GNU: -e[<param>] */
OPT_EOF_STRING1 = 1 << OPTBIT_EOF_STRING1, /* SUS: -E<param> */
OPT_INTERACTIVE = IF_FEATURE_XARGS_SUPPORT_CONFIRMATION((1 << OPTBIT_INTERACTIVE)) + 0,
OPT_TERMINATE = IF_FEATURE_XARGS_SUPPORT_TERMOPT( (1 << OPTBIT_TERMINATE )) + 0,
OPT_ZEROTERM = IF_FEATURE_XARGS_SUPPORT_ZERO_TERM( (1 << OPTBIT_ZEROTERM )) + 0,
};
#define OPTION_STR "+trn:s:e::E:" \
IF_FEATURE_XARGS_SUPPORT_CONFIRMATION("p") \
IF_FEATURE_XARGS_SUPPORT_TERMOPT( "x") \
IF_FEATURE_XARGS_SUPPORT_ZERO_TERM( "0")
int xargs_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int xargs_main(int argc, char **argv)
{
int i;
int child_error = 0;
char *max_args;
char *max_chars;
char *buf;
unsigned opt;
int n_max_chars;
int n_max_arg;
#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
char* FAST_FUNC (*read_args)(int, int, char*) = process_stdin;
#else
#define read_args process_stdin
#endif
INIT_G();
#if ENABLE_DESKTOP && ENABLE_LONG_OPTS
/* For example, Fedora's build system uses --no-run-if-empty */
applet_long_options =
"no-run-if-empty\0" No_argument "r"
;
#endif
opt = getopt32(argv, OPTION_STR, &max_args, &max_chars, &G.eof_str, &G.eof_str);
/* -E ""? You may wonder why not just omit -E?
* This is used for portability:
* old xargs was using "_" as default for -E / -e */
if ((opt & OPT_EOF_STRING1) && G.eof_str[0] == '\0')
G.eof_str = NULL;
if (opt & OPT_ZEROTERM)
IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(read_args = process0_stdin);
argv += optind;
argc -= optind;
if (!argv[0]) {
/* default behavior is to echo all the filenames */
*--argv = (char*)"echo";
argc++;
}
/* -s NUM default. fileutils-4.4.2 uses 128k, but I heasitate
* to use such a big value - first need to change code to use
* growable buffer instead of fixed one.
*/
n_max_chars = 32 * 1024;
/* Make smaller if system does not allow our default value.
* The Open Group Base Specifications Issue 6:
* "The xargs utility shall limit the command line length such that
* when the command line is invoked, the combined argument
* and environment lists (see the exec family of functions
* in the System Interfaces volume of IEEE Std 1003.1-2001)
* shall not exceed {ARG_MAX}-2048 bytes".
*/
{
long arg_max = 0;
#if defined _SC_ARG_MAX
arg_max = sysconf(_SC_ARG_MAX) - 2048;
#elif defined ARG_MAX
arg_max = ARG_MAX - 2048;
#endif
if (arg_max > 0 && n_max_chars > arg_max)
n_max_chars = arg_max;
}
if (opt & OPT_UPTO_SIZE) {
n_max_chars = xatou_range(max_chars, 1, INT_MAX);
}
/* Account for prepended fixed arguments */
{
size_t n_chars = 0;
for (i = 0; argv[i]; i++) {
n_chars += strlen(argv[i]) + 1;
}
n_max_chars -= n_chars;
}
/* Sanity check */
if (n_max_chars <= 0) {
bb_error_msg_and_die("can't fit single argument within argument list size limit");
}
buf = xzalloc(n_max_chars + 1);
n_max_arg = n_max_chars;
if (opt & OPT_UPTO_NUMBER) {
n_max_arg = xatou_range(max_args, 1, INT_MAX);
/* Not necessary, we use growable args[]: */
/* if (n_max_arg > n_max_chars) n_max_arg = n_max_chars */
}
/* Allocate pointers for execvp */
/* We can statically allocate (argc + n_max_arg + 1) elements
* and do not bother with resizing args[], but on 64-bit machines
* this results in args[] vector which is ~8 times bigger
* than n_max_chars! That is, with n_max_chars == 20k,
* args[] will take 160k (!), which will most likely be
* almost entirely unused.
*/
/* See store_param() for matching 256-step growth logic */
G.args = xmalloc(sizeof(G.args[0]) * ((argc + 0xff) & ~0xff));
/* Store the command to be executed, part 1 */
for (i = 0; argv[i]; i++)
G.args[i] = argv[i];
while (1) {
char *rem;
G.idx = argc;
rem = read_args(n_max_chars, n_max_arg, buf);
store_param(NULL);
if (!G.args[argc]) {
if (*rem != '\0')
bb_error_msg_and_die("argument line too long");
if (opt & OPT_NO_EMPTY)
break;
}
opt |= OPT_NO_EMPTY;
if (opt & (OPT_INTERACTIVE | OPT_VERBOSE)) {
const char *fmt = " %s" + 1;
char **args = G.args;
for (i = 0; args[i]; i++) {
fprintf(stderr, fmt, args[i]);
fmt = " %s";
}
if (!(opt & OPT_INTERACTIVE))
bb_putchar_stderr('\n');
}
if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
child_error = xargs_exec();
}
if (child_error > 0 && child_error != 123) {
break;
}
overlapping_strcpy(buf, rem);
} /* while */
if (ENABLE_FEATURE_CLEAN_UP) {
free(G.args);
free(buf);
}
return child_error;
}
#ifdef TEST
const char *applet_name = "debug stuff usage";
void bb_show_usage(void)
{
fprintf(stderr, "Usage: %s [-p] [-r] [-t] -[x] [-n max_arg] [-s max_chars]\n",
applet_name);
exit(EXIT_FAILURE);
}
int main(int argc, char **argv)
{
return xargs_main(argc, argv);
}
#endif /* TEST */