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#include <sys/wait.h>
#include <signal.h>
#include <errno.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#ifndef MAX_PARAM
#define MAX_PARAM 10
#endif
/*
* start child process
*/
int new_process(char * const cmd_line[MAX_PARAM])
{
int proc_status;
pid_t pid;
pid_t w;
struct stat file_status;
/* memory for storage of function pointers from the signal handling routines */
void (*int_stat)(int);
void (*quit_stat)(int);
void (*usr2_stat)(int);
/*
* check command file
*/
/* search file */
if (stat(cmd_line[0], &file_status) < 0) {
fprintf(stderr, "Cannot find program '%s'.\n", cmd_line[0]);
fprintf(stderr, "You must specify path for '%s'.\n", cmd_line[0]);
return -errno;
}
proc_status = 0;
/* check file status and permissions */
if (file_status.st_mode & S_IFREG) {
if (!(file_status.st_mode & S_IXOTH)) {
if (!(file_status.st_mode & S_IXGRP)) {
if (!(file_status.st_mode & S_IXUSR)) {
proc_status = -EACCES;
} else if (file_status.st_uid != getuid()) {
proc_status = -EACCES;
}
} else if ((file_status.st_gid != getgid()) && (file_status.st_uid != getuid())) {
proc_status = -EACCES;
}
}
} else {
proc_status = -EACCES;
}
if (proc_status != 0) {
fprintf(stderr, "No permissions to execute program '%s'.\n", cmd_line[0]);
return proc_status;
}
if ( (pid = fork() ) == 0) {
execv(cmd_line[0], cmd_line);
}
/* for waiting ingnoring special interrupts */
int_stat = signal(SIGINT, SIG_IGN);
quit_stat = signal(SIGQUIT, SIG_IGN);
usr2_stat = signal(SIGUSR2, SIG_IGN);
/* waiting for the end of the child process */
while ( ( (w = wait(&proc_status)) != pid ) && (w != -1) )
;
if (w == -1) {
proc_status = -errno;
}
/* restore pointers from signal handling routines */
signal(SIGINT, int_stat);
signal(SIGQUIT, quit_stat);
signal(SIGUSR2, usr2_stat);
return proc_status;
}
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