xargs: optional support for -P NUM. Closes 9511
Based on patch by Johannes Schindelin <johannes.schindelin@gmx.de> function old new delta xargs_exec - 294 +294 packed_usage 31757 31772 +15 xargs_main 787 719 -68 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 1/1 up/down: 309/-68) Total: 241 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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Denys Vlasenko
parent
b270be3fb3
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14551b7036
@ -59,6 +59,11 @@
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//config: depends on XARGS
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//config: help
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//config: Support -I STR and -i[STR] options.
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//config:
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//config:config FEATURE_XARGS_SUPPORT_PARALLEL
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//config: bool "Enable -P N: processes to run in parallel"
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//config: default y
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//config: depends on XARGS
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//applet:IF_XARGS(APPLET_NOEXEC(xargs, xargs, BB_DIR_USR_BIN, BB_SUID_DROP, xargs))
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@ -99,38 +104,121 @@ struct globals {
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#endif
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const char *eof_str;
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int idx;
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#if ENABLE_FEATURE_XARGS_SUPPORT_PARALLEL
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int running_procs;
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int max_procs;
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#endif
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smalluint xargs_exitcode;
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} FIX_ALIASING;
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#define G (*(struct globals*)bb_common_bufsiz1)
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#define INIT_G() do { \
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setup_common_bufsiz(); \
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G.eof_str = NULL; /* need to clear by hand because we are NOEXEC applet */ \
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G.idx = 0; \
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IF_FEATURE_XARGS_SUPPORT_PARALLEL(G.running_procs = 0;) \
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IF_FEATURE_XARGS_SUPPORT_PARALLEL(G.max_procs = 1;) \
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G.xargs_exitcode = 0; \
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IF_FEATURE_XARGS_SUPPORT_REPL_STR(G.repl_str = "{}";) \
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IF_FEATURE_XARGS_SUPPORT_REPL_STR(G.eol_ch = '\n';) \
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} while (0)
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/*
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* Returns 0 if xargs should continue (but may set G.xargs_exitcode to 123).
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* Else sets G.xargs_exitcode to error code and returns nonzero.
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*
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* If G.max_procs == 0, performs final waitpid() loop for all children.
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*/
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static int xargs_exec(void)
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{
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int status;
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#if !ENABLE_FEATURE_XARGS_SUPPORT_PARALLEL
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status = spawn_and_wait(G.args);
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#else
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if (G.max_procs == 1) {
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status = spawn_and_wait(G.args);
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} else {
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pid_t pid;
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int wstat;
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again:
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if (G.running_procs >= G.max_procs)
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pid = safe_waitpid(-1, &wstat, 0);
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else
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pid = wait_any_nohang(&wstat);
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if (pid > 0) {
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/* We may have children we don't know about:
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* sh -c 'sleep 1 & exec xargs ...'
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* Do not make G.running_procs go negative.
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*/
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if (G.running_procs != 0)
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G.running_procs--;
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status = WIFSIGNALED(wstat)
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? 0x180 + WTERMSIG(wstat)
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: WEXITSTATUS(wstat);
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if (status > 0 && status < 255) {
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/* See below why 123 does not abort */
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G.xargs_exitcode = 123;
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status = 0;
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}
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if (status == 0)
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goto again; /* maybe we have more children? */
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/* else: "bad" status, will bail out */
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} else if (G.max_procs != 0) {
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/* Not in final waitpid() loop,
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* and G.running_procs < G.max_procs: start more procs
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*/
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status = spawn(G.args);
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/* here "status" actually holds pid, or -1 */
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if (status > 0) {
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G.running_procs++;
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status = 0;
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}
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/* else: status == -1 (failed to fork or exec) */
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} else {
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/* final waitpid() loop: must be ECHILD "no more children" */
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status = 0;
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}
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}
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#endif
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/* Manpage:
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* """xargs exits with the following status:
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* 0 if it succeeds
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* 123 if any invocation of the command exited with status 1-125
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* 124 if the command exited with status 255
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* ("""If any invocation of the command exits with a status of 255,
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* xargs will stop immediately without reading any further input.
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* An error message is issued on stderr when this happens.""")
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* 125 if the command is killed by a signal
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* 126 if the command cannot be run
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* 127 if the command is not found
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* 1 if some other error occurred."""
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*/
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if (status < 0) {
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bb_simple_perror_msg(G.args[0]);
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return errno == ENOENT ? 127 : 126;
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status = (errno == ENOENT) ? 127 : 126;
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}
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else if (status >= 0x180) {
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bb_error_msg("'%s' terminated by signal %d",
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G.args[0], status - 0x180);
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status = 125;
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}
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else if (status != 0) {
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if (status == 255) {
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bb_error_msg("%s: exited with status 255; aborting", G.args[0]);
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return 124;
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}
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if (status >= 0x180) {
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bb_error_msg("'%s' terminated by signal %d",
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G.args[0], status - 0x180);
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return 125;
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/* "123 if any invocation of the command exited with status 1-125"
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* This implies that nonzero exit code is remembered,
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* but does not cause xargs to stop: we return 0.
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*/
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G.xargs_exitcode = 123;
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status = 0;
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}
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if (status)
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return 123;
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return 0;
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if (status != 0)
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G.xargs_exitcode = status;
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return status;
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}
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/* In POSIX/C locale isspace is only these chars: "\t\n\v\f\r" and space.
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@ -436,6 +524,9 @@ static int xargs_ask_confirmation(void)
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//usage: IF_FEATURE_XARGS_SUPPORT_REPL_STR(
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//usage: "\n -I STR Replace STR within PROG ARGS with input line"
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//usage: )
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//usage: IF_FEATURE_XARGS_SUPPORT_PARALLEL(
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//usage: "\n -P N Run up to N PROGs in parallel"
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//usage: )
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//usage: IF_FEATURE_XARGS_SUPPORT_TERMOPT(
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//usage: "\n -x Exit if size is exceeded"
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//usage: )
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@ -473,14 +564,14 @@ enum {
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IF_FEATURE_XARGS_SUPPORT_CONFIRMATION("p") \
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IF_FEATURE_XARGS_SUPPORT_TERMOPT( "x") \
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IF_FEATURE_XARGS_SUPPORT_ZERO_TERM( "0") \
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IF_FEATURE_XARGS_SUPPORT_REPL_STR( "I:i::")
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IF_FEATURE_XARGS_SUPPORT_REPL_STR( "I:i::") \
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IF_FEATURE_XARGS_SUPPORT_PARALLEL( "P:+")
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int xargs_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int xargs_main(int argc UNUSED_PARAM, char **argv)
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{
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int initial_idx;
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int i;
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int child_error = 0;
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char *max_args;
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char *max_chars;
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char *buf;
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@ -500,8 +591,14 @@ int xargs_main(int argc UNUSED_PARAM, char **argv)
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"no-run-if-empty\0" No_argument "r",
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&max_args, &max_chars, &G.eof_str, &G.eof_str
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IF_FEATURE_XARGS_SUPPORT_REPL_STR(, &G.repl_str, &G.repl_str)
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IF_FEATURE_XARGS_SUPPORT_PARALLEL(, &G.max_procs)
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);
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#if ENABLE_FEATURE_XARGS_SUPPORT_PARALLEL
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if (G.max_procs <= 0) /* -P0 means "run lots of them" */
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G.max_procs = 100; /* let's not go crazy high */
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#endif
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/* -E ""? You may wonder why not just omit -E?
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* This is used for portability:
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* old xargs was using "_" as default for -E / -e */
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@ -620,11 +717,8 @@ int xargs_main(int argc UNUSED_PARAM, char **argv)
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}
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if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
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child_error = xargs_exec();
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}
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if (child_error > 0 && child_error != 123) {
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break;
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if (xargs_exec() != 0)
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break; /* G.xargs_exitcode is set by xargs_exec() */
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}
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overlapping_strcpy(buf, rem);
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@ -635,7 +729,12 @@ int xargs_main(int argc UNUSED_PARAM, char **argv)
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free(buf);
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}
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return child_error;
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#if ENABLE_FEATURE_XARGS_SUPPORT_PARALLEL
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G.max_procs = 0;
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xargs_exec(); /* final waitpid() loop */
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#endif
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return G.xargs_exitcode;
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}
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