busybox/findutils/xargs.c
Denys Vlasenko d5fa1a0f49 xargs: code shrink -15 bytes
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2010-06-13 03:43:43 +02:00

569 lines
14 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini xargs implementation for busybox
* Options are supported: "-prtx -n max_arg -s max_chars -e[ouf_str]"
*
* (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 the GPL v2 or later, see the file LICENSE in this tarball.
*
* xargs is described in the Single Unix Specification v3 at
* http://www.opengroup.org/onlinepubs/007904975/utilities/xargs.html
*
*/
//kbuild:lib-$(CONFIG_XARGS) += xargs.o
//config:
//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.
#include "libbb.h"
/* This is a NOEXEC applet. Be very careful! */
/* COMPAT: SYSV version defaults size (and has a max value of) to 470.
We try to make it as large as possible. */
#if !defined(ARG_MAX) && defined(_SC_ARG_MAX)
# define ARG_MAX sysconf(_SC_ARG_MAX)
#endif
#if !defined(ARG_MAX)
# define ARG_MAX 470
#endif
#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
/*
This function has special algorithm.
Don't use fork and include to main!
*/
static int xargs_exec(char **args)
{
int status;
status = spawn_and_wait(args);
if (status < 0) {
bb_simple_perror_msg(args[0]);
return errno == ENOENT ? 127 : 126;
}
if (status == 255) {
bb_error_msg("%s: exited with status 255; aborting", args[0]);
return 124;
}
if (status >= 0x180) {
bb_error_msg("%s: terminated by signal %d",
args[0], status - 0x180);
return 125;
}
if (status)
return 123;
return 0;
}
typedef struct xlist_t {
struct xlist_t *link;
size_t length;
char xstr[1];
} xlist_t;
/* 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); })
#if ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
static xlist_t* process_stdin(xlist_t *list_arg,
const char *eof_str, size_t mc, char *buf)
{
#define NORM 0
#define QUOTE 1
#define BACKSLASH 2
#define SPACE 4
char *s = NULL; /* start of the word */
char *p = NULL; /* pointer to end of the word */
char q = '\0'; /* quote char */
char state = NORM;
char eof_str_detected = 0;
size_t line_l = 0; /* size of loaded args */
xlist_t *cur;
xlist_t *prev;
prev = cur = list_arg;
while (cur) {
prev = cur;
line_l += cur->length;
cur = cur->link;
}
while (1) {
int c = getchar();
if (c == EOF) {
if (s)
goto unexpected_eof;
break;
}
if (eof_str_detected) /* skip till EOF */
continue;
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 (s) {
unexpected_eof:
state = SPACE;
c = '\0';
goto set;
}
} else {
if (s == NULL)
s = p = buf;
if (c == '\\') {
state = BACKSLASH;
} else if (c == '\'' || c == '"') {
q = c;
state = QUOTE;
} else {
set:
if ((size_t)(p - buf) >= mc)
bb_error_msg_and_die("argument line too long");
*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 (eof_str) {
eof_str_detected = (strcmp(s, eof_str) == 0);
}
if (!eof_str_detected) {
size_t length = (p - buf);
/* Dont xzalloc - it can be quite big */
cur = xmalloc(offsetof(xlist_t, xstr) + length);
cur->link = NULL;
cur->length = length;
memcpy(cur->xstr, s, length);
if (prev == NULL) {
list_arg = cur;
} else {
prev->link = cur;
}
prev = cur;
line_l += length;
if (line_l > mc) /* limit stop memory usage */
break;
}
s = NULL;
state = NORM;
}
}
return list_arg;
}
#else
/* The variant does not support single quotes, double quotes or backslash */
static xlist_t* process_stdin(xlist_t *list_arg,
const char *eof_str, size_t mc, char *buf)
{
char eof_str_detected = 0;
char *s = NULL; /* start of the word */
char *p = NULL; /* pointer to end of the word */
size_t line_l = 0; /* size of loaded args */
xlist_t *cur;
xlist_t *prev;
prev = cur = list_arg;
while (cur) {
prev = cur;
line_l += cur->length;
cur = cur->link;
}
while (1) {
int c = getchar();
if (c == EOF) {
if (s == NULL)
break;
}
if (eof_str_detected) { /* skip till EOF */
continue;
}
if (c == EOF || ISSPACE(c)) {
if (s == NULL)
continue;
c = EOF;
}
if (s == NULL)
s = p = buf;
if ((size_t)(p - buf) >= mc)
bb_error_msg_and_die("argument line too long");
*p++ = (c == EOF ? '\0' : c);
if (c == EOF) { /* word's delimiter or EOF detected */
/* A full word is loaded */
if (eof_str) {
eof_str_detected = (strcmp(s, eof_str) == 0);
}
if (!eof_str_detected) {
size_t length = (p - buf);
/* Dont xzalloc - it can be quite big */
cur = xmalloc(offsetof(xlist_t, xstr) + length);
cur->link = NULL;
cur->length = length;
memcpy(cur->xstr, s, length);
if (prev == NULL) {
list_arg = cur;
} else {
prev->link = cur;
}
prev = cur;
line_l += length;
if (line_l > mc) /* limit stop memory usage */
break;
}
s = NULL;
}
}
return list_arg;
}
#endif /* FEATURE_XARGS_SUPPORT_QUOTES */
#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 /* FEATURE_XARGS_SUPPORT_CONFIRMATION */
#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
static xlist_t* process0_stdin(xlist_t *list_arg,
const char *eof_str UNUSED_PARAM, size_t mc, char *buf)
{
char *s = NULL; /* start of the word */
char *p = NULL; /* pointer to end of the word */
size_t line_l = 0; /* size of loaded args */
xlist_t *cur;
xlist_t *prev;
prev = cur = list_arg;
while (cur) {
prev = cur;
line_l += cur->length;
cur = cur->link;
}
while (1) {
int c = getchar();
if (c == EOF) {
if (s == NULL)
break;
c = '\0';
}
if (s == NULL)
s = p = buf;
if ((size_t)(p - buf) >= mc)
bb_error_msg_and_die("argument line too long");
*p++ = c;
if (c == '\0') { /* word's delimiter or EOF detected */
/* A full word is loaded */
size_t length = (p - buf);
/* Dont xzalloc - it can be quite big */
cur = xmalloc(offsetof(xlist_t, xstr) + length);
cur->link = NULL;
cur->length = length;
memcpy(cur->xstr, s, length);
if (prev == NULL) {
list_arg = cur;
} else {
prev->link = cur;
}
prev = cur;
line_l += length;
if (line_l > mc) /* limit stop memory usage */
break;
s = NULL;
}
}
return list_arg;
}
#endif /* FEATURE_XARGS_SUPPORT_ZERO_TERM */
/* 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)
{
xlist_t *list = NULL;
int child_error = 0;
char *max_args;
char *max_chars;
char *buf;
int n_max_arg;
const char *eof_str = NULL;
unsigned opt;
size_t n_max_chars;
#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
xlist_t* (*read_args)(xlist_t*, const char*, size_t, char*) = process_stdin;
#else
#define read_args process_stdin
#endif
opt = getopt32(argv, OPTION_STR, &max_args, &max_chars, &eof_str, &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) && eof_str[0] == '\0')
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++;
}
/* 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".
*/
n_max_chars = ARG_MAX; /* might be calling sysconf(_SC_ARG_MAX) */
if (n_max_chars < 4*1024); /* paranoia */
n_max_chars = 4*1024;
n_max_chars -= 2048;
/* Sanity check for systems with huge ARG_MAX defines (e.g., Suns which
* have it at 1 meg). Things will work fine with a large ARG_MAX
* but it will probably hurt the system more than it needs to;
* an array of this size is allocated.
*/
if (n_max_chars > 20 * 1024)
n_max_chars = 20 * 1024;
if (opt & OPT_UPTO_SIZE) {
int i;
size_t n_chars = 0;
n_max_chars = xatoul_range(max_chars, 1, n_max_chars);
for (i = 0; argv[i]; i++) {
n_chars += strlen(argv[i]) + 1;
}
n_max_chars -= n_chars;
if ((ssize_t)n_max_chars <= 0) {
bb_error_msg_and_die("can't fit single argument within argument list size limit");
}
}
buf = xmalloc(n_max_chars);
if (opt & OPT_UPTO_NUMBER) {
n_max_arg = xatoul_range(max_args, 1, INT_MAX);
} else {
n_max_arg = n_max_chars;
}
while ((list = read_args(list, eof_str, n_max_chars, buf)) != NULL
|| !(opt & OPT_NO_EMPTY)
) {
char **args;
xlist_t *cur;
int i, n;
size_t n_chars = 0;
opt |= OPT_NO_EMPTY;
n = 0;
#if ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
for (cur = list; cur;) {
n_chars += cur->length;
n++;
cur = cur->link;
if (n_chars > n_max_chars || (n == n_max_arg && cur)) {
if (opt & OPT_TERMINATE)
bb_error_msg_and_die("argument list too long");
break;
}
}
#else
for (cur = list; cur; cur = cur->link) {
n_chars += cur->length;
n++;
if (n_chars > n_max_chars || n == n_max_arg) {
break;
}
}
#endif
/* allocate pointers for execvp */
args = xzalloc(sizeof(args[0]) * (argc + n + 1));
/* store the command to be executed
* (taken from the command line) */
for (i = 0; argv[i]; i++)
args[i] = argv[i];
/* (taken from stdin) */
for (cur = list; n; cur = cur->link) {
args[i++] = cur->xstr;
n--;
}
if (opt & (OPT_INTERACTIVE | OPT_VERBOSE)) {
for (i = 0; args[i]; i++) {
if (i)
bb_putchar_stderr(' ');
fputs(args[i], stderr);
}
if (!(opt & OPT_INTERACTIVE))
bb_putchar_stderr('\n');
}
if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
child_error = xargs_exec(args);
}
/* clean up */
for (i = argc; args[i]; i++) {
cur = list;
list = list->link;
free(cur);
}
free(args);
if (child_error > 0 && child_error != 123) {
break;
}
} /* while */
if (ENABLE_FEATURE_CLEAN_UP)
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 */