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recursion

This commit is contained in:
dtb 2022-11-21 14:14:22 -05:00
parent b484c81320
commit f85bb632e2

View File

@ -7,44 +7,36 @@
static char *program_name = "pscat";
/* Originally designed to use parentheses but changed to brackets to escape the
* hassle of escaping them from the Bourne shell. */
#define L_PAREN '['
#define R_PAREN ']'
int main(int argc, char *argv[]){
char **psstart;
int
forking(char **argv){
int child;
int i;
unsigned int retval;
int terms;
char **corr;
retval = 0;
corr = corresponding_arg(argv, L_PAREN, R_PAREN);
*corr = NULL;
if(fork() == 0){
execvp(argv[1], argv+1);
}else{
wait(&child);
argv = corr;
if(*++argv == NULL)
return WIFEXITED(child) * WEXITSTATUS(child);
else
return forking(argv);
}
}
if((terms = check_arg(++argv, L_PAREN, R_PAREN)) == 0){
int main(int argc, char *argv[]){
if((check_arg(++argv, L_PAREN, R_PAREN)) == 0){
fprintf(stderr,
"Usage: %s \"[\" [utility [argument...]] \"]\" ...\n",
argv[-1] == NULL ? program_name : argv[-1]
);
return EX_USAGE;
}
/* loop starts with *argv -> the next L_PAREN */
for(i = 0; i < terms; ++i){
psstart = argv + 1;
argv = corresponding_arg(argv, L_PAREN, R_PAREN);
/* *argv -> the corresponding R_PAREN. turn it into NULL to
* terminate the argument list to send to execvp(3) */
*argv = NULL;
if(fork() == 0){
execvp(psstart[0], psstart);
}else
wait(&child);
/* interpret status information from wait(2) */
if(WIFEXITED(child))
retval += WEXITSTATUS(child);
++argv;
}
return retval;
return forking(argv);
}