Quoting POSIX[0]: "Care should be taken, also, to call _exit() rather than exit() if exec cannot be used, since exit() flushes and closes standard I/O channels, thereby damaging the parent process' standard I/O data structures. (Even with fork(), it is wrong to call exit(), since buffered data would then be flushed twice.)" [0]: http://pubs.opengroup.org/onlinepubs/009695399/functions/vfork.html
263 lines
4.1 KiB
C
263 lines
4.1 KiB
C
/* See LICENSE file for copyright and license details. */
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#include <sys/wait.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "util.h"
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enum {
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NARGS = 10000
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};
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static int inputc(void);
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static void deinputc(int);
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static void fillargbuf(int);
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static int eatspace(void);
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static int parsequote(int);
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static int parseescape(void);
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static char *poparg(void);
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static void waitchld(void);
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static void spawn(void);
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static char *cmd[NARGS];
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static char *argb;
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static size_t argbsz;
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static size_t argbpos;
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static long maxargs = 0;
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static int nerrors = 0;
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static char *eofstr;
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static int rflag = 0, nflag = 0;
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static int
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inputc(void)
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{
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int ch;
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ch = getc(stdin);
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if (ch == EOF && ferror(stdin))
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eprintf("stdin: read error:");
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return ch;
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}
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static void
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deinputc(int ch)
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{
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ungetc(ch, stdin);
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}
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static void
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fillargbuf(int ch)
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{
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if (argbpos >= argbsz) {
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argbsz = argbpos == 0 ? 1 : argbsz * 2;
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argb = erealloc(argb, argbsz);
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}
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argb[argbpos] = ch;
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}
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static int
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eatspace(void)
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{
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int ch;
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while ((ch = inputc()) != EOF) {
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switch (ch) {
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case ' ': case '\t': case '\n':
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break;
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default:
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deinputc(ch);
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return ch;
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}
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}
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return -1;
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}
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static int
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parsequote(int q)
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{
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int ch;
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while ((ch = inputc()) != EOF) {
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if (ch == q)
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return 0;
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if (ch != '\n') {
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fillargbuf(ch);
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argbpos++;
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}
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}
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return -1;
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}
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static int
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parseescape(void)
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{
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int ch;
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if ((ch = inputc()) != EOF) {
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fillargbuf(ch);
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argbpos++;
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return ch;
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}
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return -1;
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}
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static char *
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poparg(void)
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{
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int ch;
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argbpos = 0;
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if (eatspace() < 0)
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return NULL;
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while ((ch = inputc()) != EOF) {
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switch (ch) {
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case ' ': case '\t': case '\n':
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goto out;
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case '\'':
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if (parsequote('\'') < 0)
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eprintf("unterminated single quote\n");
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break;
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case '\"':
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if (parsequote('\"') < 0)
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eprintf("unterminated double quote\n");
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break;
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case '\\':
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if (parseescape() < 0)
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eprintf("backslash at EOF\n");
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break;
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default:
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fillargbuf(ch);
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argbpos++;
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break;
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}
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}
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out:
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fillargbuf('\0');
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if (eofstr && strcmp(argb, eofstr) == 0)
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return NULL;
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return argb;
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}
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static void
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waitchld(void)
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{
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int status;
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wait(&status);
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if (WIFEXITED(status)) {
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if (WEXITSTATUS(status) == 255)
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exit(124);
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if (WEXITSTATUS(status) == 127 ||
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WEXITSTATUS(status) == 126)
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exit(WEXITSTATUS(status));
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if (status != 0)
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nerrors++;
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}
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if (WIFSIGNALED(status))
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exit(125);
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}
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static void
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spawn(void)
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{
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pid_t pid;
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int savederrno;
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pid = fork();
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if (pid < 0) {
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weprintf("fork:");
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_exit(1);
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}
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if (pid == 0) {
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execvp(*cmd, cmd);
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savederrno = errno;
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weprintf("execvp %s:", *cmd);
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_exit(126 + (savederrno == ENOENT));
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}
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waitchld();
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}
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static void
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usage(void)
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{
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eprintf("usage: %s [-n maxargs] [-r] [-E eofstr] [cmd [arg...]]\n", argv0);
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}
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int
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main(int argc, char *argv[])
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{
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int leftover = 0;
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long argsz, argmaxsz;
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char *arg = "";
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int i, a;
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ARGBEGIN {
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case 'n':
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nflag = 1;
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if ((maxargs = strtol(EARGF(usage()), NULL, 10)) <= 0)
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eprintf("%s: value for -n option should be >= 1\n", argv0);
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break;
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case 'r':
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rflag = 1;
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break;
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case 'E':
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eofstr = EARGF(usage());
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break;
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default:
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usage();
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} ARGEND;
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argmaxsz = sysconf(_SC_ARG_MAX);
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if (argmaxsz < 0)
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eprintf("sysconf:");
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/* Leave some room for environment variables */
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argmaxsz -= 4 * 1024;
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do {
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argsz = 0; i = 0; a = 0;
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if (argc > 0) {
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for (; i < argc; i++) {
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cmd[i] = estrdup(argv[i]);
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argsz += strlen(cmd[i]) + 1;
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}
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} else {
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cmd[i] = estrdup("/bin/echo");
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argsz += strlen(cmd[i]) + 1;
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i++;
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}
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while (leftover == 1 || (arg = poparg())) {
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if (argsz + strlen(arg) + 1 > argmaxsz ||
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i >= NARGS - 1) {
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if (strlen(arg) + 1 > argmaxsz)
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eprintf("insufficient argument space\n");
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leftover = 1;
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break;
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}
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cmd[i] = estrdup(arg);
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argsz += strlen(cmd[i]) + 1;
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i++;
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a++;
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leftover = 0;
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if (nflag == 1 && a >= maxargs)
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break;
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}
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cmd[i] = NULL;
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if (a >= maxargs && nflag == 1)
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spawn();
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else if (!a || (i == 1 && rflag == 1))
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;
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else
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spawn();
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for (; i >= 0; i--)
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free(cmd[i]);
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} while (arg);
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free(argb);
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return nerrors > 0 ? 123 : 0;
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}
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