对于以下 C 程序，execl 返回 -1，表示 Permission Denied 错误。我检查了读，写。我的可执行文件的执行权限，它们都是 rwx。有人可以让我知道为什么 execl 返回 Permission Denied 错误吗？非常感谢
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/shm.h>
#include <errno.h>
#include <semaphore.h>
#define MAXLINE 256
#define MAXARGS 128
#define SHELL "/h/fchang03" // "/bin/sh"
key_t shmkey;
int shmid;
sem_t *sem;
int* p;
struct statStuff {
int pid; // %d
char comm[256]; // %s
char state; // %c
int ppid; // %d
int pgrp; // %d
int session; // %d
int tty_nr; // %d
int tpgid; // %d
unsigned long flags; // %lu
unsigned long minflt; // %lu
unsigned long cminflt; // %lu
unsigned long majflt; // %lu
unsigned long cmajflt; // %lu
unsigned long utime; // %lu
unsigned long stime; // %lu
long cutime; // %ld
long cstime; // %ld
long priority; // %ld
long nice; // %ld
long num_threads; // %ld
long itrealvalue; // %ld
unsigned long starttime; // %lu
unsigned long vsize; // %lu
long rss; // %ld
unsigned long rlim; // %lu
unsigned long startcode; // %lu
unsigned long endcode; // %lu
unsigned long startstack; // %lu
unsigned long kstkesp; // %lu
unsigned long kstkeip; // %lu
unsigned long signal; // %lu
unsigned long blocked; // %lu
unsigned long sigignore; // %lu
unsigned long sigcatch; // %lu
unsigned long wchan; // %lu
unsigned long nswap; // %lu
unsigned long cnswap; // %lu
int exit_signal; // %d
int processor; // %d
unsigned long rt_priority; // %lu
unsigned long policy; // %lu
unsigned long long delayacct_blkio_ticks; // %llu
} ;
static int readStat(int pid, struct statStuff *s) {
const char *format = "%d %s %c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld %lu %lu %ld %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %d %d %lu %lu %llu";
char buf[256];
FILE *proc;
sprintf(buf,"/proc/%d/stat",pid);
proc = fopen(buf,"r");
if (proc) {
if (42==fscanf(proc, format,
&s->pid,
s->comm,
&s->state,
&s->ppid,
&s->pgrp,
&s->session,
&s->tty_nr,
&s->tpgid,
&s->flags,
&s->minflt,
&s->cminflt,
&s->majflt,
&s->cmajflt,
&s->utime,
&s->stime,
&s->cutime,
&s->cstime,
&s->priority,
&s->nice,
&s->num_threads,
&s->itrealvalue,
&s->starttime,
&s->vsize,
&s->rss,
&s->rlim,
&s->startcode,
&s->endcode,
&s->startstack,
&s->kstkesp,
&s->kstkeip,
&s->signal,
&s->blocked,
&s->sigignore,
&s->sigcatch,
&s->wchan,
&s->nswap,
&s->cnswap,
&s->exit_signal,
&s->processor,
&s->rt_priority,
&s->policy,
&s->delayacct_blkio_ticks
)) {
printf("Stack start = %x\n",s->startstack);
printf("Stack end = %x\n",s->kstkesp);
fclose(proc);
return 1;
} else {
fclose(proc);
return 0;
}
} else {
return 0;
}
}
int eval(const char *cmdline)
{
char *argv[MAXARGS];
int bg;
pid_t pid;
int status;
struct statStuff test;
int value;
pid = fork();
if (pid > 0){
/* This is the parent process. */
char* p;
int n_bytes = 256;
int bytes_read;
char buffer[256];
printf("PARENT PROCESS 1\n");
// while (!(*value)){
//
// }
sleep(2);
printf("PARENT PROCESS 2\n");
sem_getvalue(sem, &value);
sprintf(buffer,"/proc/%d/maps",value);
printf("buffer = %s\n",buffer);
int fd = open(buffer,O_RDONLY);
printf("fd = %d\n",fd);
p = (char *)malloc(256);
while (bytes_read = read(fd,p,n_bytes)){
//printf("STRING = %s\n",p);
//break;
if (strstr(p,"[heap]") != NULL){
printf("%s\n",p);
}
free(p);
p = (char *)malloc(256);
// lseek(fd,256,SEEK_CUR);
}
waitpid(pid, &status, 0);
// execl(SHELL,SHELL,"-c",cmdline,NULL);
/*
memset(&test, 0, sizeof(struct statStuff));
readStat(pid, &test);
// _exit(EXIT_FAILURE);
*/
}
else if (pid < 0){
/* The fork failed. Report failure. */
status = -1;
}
else{
printf("BOO!\n");
sem = sem_open("pSem", O_CREAT | O_EXCL, pid);
printf("FOO!\n");
// sem_unlink("pSem");
printf("HOWDY\n");
// printf("ERROR = %d\n",
execl("/h/fchang03","/h/fchang03/two",0);
perror("execl");
}
}
int main(void)
{
char cmdline[MAXLINE];
char temp[MAXLINE];
shmkey = ftok("/dev/null",5);
shmid = shmget(shmkey, sizeof (int), 0644 | IPC_CREAT);
if (shmid < 0){
perror("shmget\n");
exit(1);
}
p = (int *)shmat(shmid, NULL, 0);
*p = 0;
while (1){
printf("> ");
fgets(temp, MAXLINE, stdin);
sprintf(cmdline,"./%s",temp);
if (feof(stdin)){
exit(0);
}
printf("cmdline = %s\n",cmdline);
eval(cmdline);
}
shmdt(p);
shmctl(shmid, IPC_RMID, 0);
sem_destroy(sem);
exit(0);
}