提问人：bf3019 提问时间：3/18/2021 最后编辑：Bill Lynchbf3019 更新时间：3/19/2021 访问量：193
奇怪的 Malloc 错误（以及涉及此 shell 的其他问题）
Weird Malloc Error (and other problems involving this shell)
问：
我正在为我正在处理的 C 项目开发一个 Shell，每当我直接与存储所有作业和进程的列表交互时，我总是遇到这个奇怪的 Malloc 错误，我总是得到一个奇怪的 Malloc 错误，看起来像这样：
你能帮我弄清楚这东西是怎么回事吗？如果可能的话，也许你也可以给我其他关于如何改进它的建议？因为我真的很感激。
代码如下：
*
* $ gcc shell.c csapp.c -lpthread -o shell
*
*
* $ ./shell
*/
#include "csapp.h"
#define TRUE 1
#define FALSE 0
#define MAXARGS 128
#define MAXCHARS 64
pid_t fg_pid = 0;
int next_jid = 1;
typedef struct list_t
{
pid_t pid;
int jid;
char *runstat;
char *cmdline;
struct list_t *next;
} list_t;
list_t *jobs_list = NULL;
void add_element(list_t **list, pid_t pid, int jid, char *runstat, char *cmdline)
{
list_t *e;
if (*list == NULL) // New empty list.
{
*list = (list_t *) malloc(sizeof(list_t));
(*list)->pid = pid;
(*list)->jid = jid;
(*list)->runstat = strndup(runstat, MAXCHARS);
(*list)->cmdline = strndup(cmdline, MAXCHARS);
(*list)->next = NULL;
}
else // List with at least one element.
{
// Loop through elements, so that e is left
// pointing to the last one in the list.
for (e = *list; e->next != NULL; e = e->next)
; // (Do nothing.)
e->next = (list_t *) malloc(sizeof(list_t));
e = e->next;
e->pid = pid;
e->jid = jid;
e->runstat = strndup(runstat, MAXCHARS);
e->cmdline = strndup(cmdline, MAXCHARS);
e->next = NULL;
}
}
void fg_list_handler(list_t ** list, pid_t pid, int jid) {
}
void change_running_status(list_t **list, pid_t pid, char *runstat) {
//THe code I wrote with changing statuses in the list for programs.
list_t *e;
e = *list;
if (e->next == NULL) {
strncpy(e->runstat, runstat, MAXCHARS);
} else {
for (e; e != NULL; e->next) {
if (pid == e->pid) {
strncpy(e->runstat, runstat, MAXCHARS);
break;
}
}
}
}
void sigint_handler(int signal) {
// Restore default behavior for next SIGINT (which will likely
// come from call to raise at the end of this function).
Signal(SIGINT, SIG_DFL);
if (fg_pid != 0) {
Kill(-fg_pid, SIGINT); //Exits out of the child process (- = Send to group).
printf("Job %d has been terminated by: User Interrupt (SIGINT) \n", fg_pid);
Signal(SIGINT, sigint_handler);
} else {
// Send SIGINT to self. (This time won't be caught be handler,
// will instead cause process to terminate.)
raise(SIGINT);
}
}
void sigtstp_handler(int signal) {
//Restores SIGSTOP to normal behavior.
Signal(SIGTSTP, SIG_DFL);
//Stops the process.
if (fg_pid != 0) {
kill(-fg_pid, SIGTSTP);
printf("Job %d has been stopped by: User Stop (SIGTSTP)\n", fg_pid);
Signal(SIGTSTP, sigtstp_handler);
} else {
raise(SIGTSTP);
}
}
/*
* Populate argv with pointers to places in line where arguments
* begin (and put \0 in buf where arguments end), so that argv[0] is
* pointer to first argument, argv[1] pointer to second, etc.
*
* (You should't need to make any changes to this function.)
*/
int parseline(char *line, char **argv) {
char *cp;
int in_arg = FALSE;
int argc = 0;
int bg = FALSE;
// Go through line, one character at a time, until reaching the
// newline character at the end.
for (cp = line; *cp != '\n'; cp++) {
if (in_arg) {
// If at the end of an argument...
if (*cp == ' ') {
*cp = '\0'; // Mark end of argument.
in_arg = FALSE;
}
} else if (*cp != ' ') { // If at beginning of new argument...
argv[argc++] = cp; // Set argv array element to point to
// new argument.
in_arg = TRUE;
}
}
*cp = '\0'; // Mark end of last argument (which was probably
// followed by \n, not space).
// If at least one argument, and last argument is &, process is
// to be run in background.
if (argc > 0 && *argv[argc - 1] == '&') {
bg = TRUE;
argv[argc - 1] = NULL; // Overwrite address of "&" to mark
// end of argv.
} else { // (Process should run in foreground.)
argv[argc] = NULL; // Mark end of argv.
}
return bg;
}
/*
* If argv[0] is a builtin command, run it and return TRUE. If it's
* not, return FALSE.
*/
int builtin_command(char **argv) {
if (strcmp(argv[0], "quit") == 0) {
// (Don't bother to return, just end the program.)
exit(0);
} else if (strcmp(argv[0], "&") == 0) {
// (Ignore & if it isn't preceded by a command.)
return TRUE;
} else if (strcmp(argv[0], "jobs") == 0) {
// Prints list of background and stopped jobs.
list_t *e;
char *runstat[MAXLINE];
for (e = jobs_list; e != NULL; e = e->next) {
strncpy(runstat, e->runstat, MAXCHARS);
//Eventually going to add an additional argument to allow it to print different lists depending on the argument.
//Prints the process only if it's currently running in the system.
if (strncmp(e->runstat, "running", MAXCHARS) == 0) {
printf("[%d], %d, %s, %s", e->jid, e->pid, e->runstat, e->cmdline);
}
}
return TRUE;
} else if (strcmp(argv[0], "bg")) {
}
return FALSE;
}
/*
* Evaluate command (a line of arguments).
*/
void eval(char *cmdline, char **envp) {
char *argv[MAXARGS];
char buf[MAXLINE];
int bg;
pid_t pid;
int jid;
char *runstat[MAXLINE];
//Used for my current implementation of status checking.
int status;
// Copy cmdline to buf, use parseline to populate argv based
// on what's in buf (and set bg based on value returned from
// parseline).
strcpy(buf, cmdline);
bg = parseline(buf, argv);
// If at least one argument, and it's not a builtin command...
// (If it is a builtin command the builtin_command function will
// run it too, not just check whether it's builtin.)
if (argv[0] != NULL && !builtin_command(argv)) {
pid = Fork();
if (pid == 0) { // In child.
//Added to work with child processes and groups of processes.
pid = getpid();
setpgid(pid, pid);
if (execve(argv[0], argv, envp) < 0) {
printf("%s is an invalid command.\n", argv[0]);
exit(0);
}
} else if (!bg) { // In parent, child running in foreground.
fg_pid = pid;
strncpy(runstat, "running", MAXCHARS);
jid = next_jid++;
//Testing Print.
printf("[%d] %d %s %s", jid, pid, runstat, cmdline);
add_element(&jobs_list, pid, jid, runstat, cmdline);
if (waitpid(pid, &status, WUNTRACED) != 0)
{
if (fg_pid != 0) {
//added check due to the first if executing down here for no reason.
if (WIFEXITED(status) >= 1) {
strncpy(runstat, "exited", MAXCHARS);
//change_running_status(&jobs_list, pid, runstat);
printf("[%d] %d %s %s", jid, pid, runstat, cmdline);
} else if (WIFSIGNALED(status) >= 1) {
strncpy(runstat, "interrupted", MAXCHARS);
//change_running_status(&jobs_list, pid, runstat);
printf("[%d] %d %s %s", jid, pid, runstat, cmdline);
} else if (WIFSTOPPED(status) >= 1) {
strncpy(runstat, "stopped", MAXCHARS);
change_running_status(&jobs_list, pid, runstat);
printf("[%d] %d %s %s", jid, pid, runstat, cmdline);
}
}
}
fg_pid = 0;
} else { // In parent, child running in background.
//Implemented the whole running thing in my usual crude methods of doing so.
strncpy(runstat, "running", MAXCHARS);
jid = next_jid++;
//runstat = 'Running';
//printf("[%d] %d %s %s", jid, pid, runstat, cmdline);
add_element(&jobs_list, pid, jid, runstat, cmdline);
}
}
}
int main(int argc, char **argv, char **envp) {
char cmdline[MAXLINE];
Signal(SIGINT, sigint_handler);
Signal(SIGTSTP, sigtstp_handler);
while (TRUE) { // exit(0) will be called from builtin_command
// if user enters "quit" command.
printf("> ");
Fgets(cmdline, MAXLINE, stdin);
eval(cmdline, envp);
}
}
答：
-1赞
bf3019
3/18/2021
#1
哦，这还不是全部代码。还有其他几个文件（忽略 CSAPP.c 的错误。当您在编译中使用 lpthread 时，它们会自行解决）。
* csapp.h
*/
/* $begin csapp.h */
#ifndef __CSAPP_H__
#define __CSAPP_H__
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <setjmp.h>
#include <signal.h>
#include <dirent.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <errno.h>
#include <math.h>
#include <pthread.h>
#include <semaphore.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
/* Default file permissions are DEF_MODE & ~DEF_UMASK */
/* $begin createmasks */
#define DEF_MODE S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH
#define DEF_UMASK S_IWGRP|S_IWOTH
/* $end createmasks */
/* Simplifies calls to bind(), connect(), and accept() */
/* $begin sockaddrdef */
typedef struct sockaddr SA;
/* $end sockaddrdef */
/* Persistent state for the robust I/O (Rio) package */
/* $begin rio_t */
#define RIO_BUFSIZE 8192
typedef struct {
int rio_fd; /* Descriptor for this internal buf */
int rio_cnt; /* Unread bytes in internal buf */
char *rio_bufptr; /* Next unread byte in internal buf */
char rio_buf[RIO_BUFSIZE]; /* Internal buffer */
} rio_t;
/* $end rio_t */
/* External variables */
extern int h_errno; /* Defined by BIND for DNS errors */
extern char **environ; /* Defined by libc */
/* Misc constants */
#define MAXLINE 8192 /* Max text line length */
#define MAXBUF 8192 /* Max I/O buffer size */
#define LISTENQ 1024 /* Second argument to listen() */
/* Our own error-handling functions */
void unix_error(char *msg);
void posix_error(int code, char *msg);
void dns_error(char *msg);
void gai_error(int code, char *msg);
void app_error(char *msg);
/* Process control wrappers */
pid_t Fork(void);
void Execve(const char *filename, char *const argv[], char *const envp[]);
pid_t Wait(int *status);
pid_t Waitpid(pid_t pid, int *iptr, int options);
void Kill(pid_t pid, int signum);
unsigned int Sleep(unsigned int secs);
void Pause(void);
unsigned int Alarm(unsigned int seconds);
void Setpgid(pid_t pid, pid_t pgid);
pid_t Getpgrp();
/* Signal wrappers */
typedef void handler_t(int);
handler_t *Signal(int signum, handler_t *handler);
void Sigprocmask(int how, const sigset_t *set, sigset_t *oldset);
void Sigemptyset(sigset_t *set);
void Sigfillset(sigset_t *set);
void Sigaddset(sigset_t *set, int signum);
void Sigdelset(sigset_t *set, int signum);
int Sigismember(const sigset_t *set, int signum);
int Sigsuspend(const sigset_t *set);
/* Sio (Signal-safe I/O) routines */
ssize_t sio_puts(char s[]);
ssize_t sio_putl(long v);
void sio_error(char s[]);
/* Sio wrappers */
ssize_t Sio_puts(char s[]);
ssize_t Sio_putl(long v);
void Sio_error(char s[]);
/* Unix I/O wrappers */
int Open(const char *pathname, int flags, mode_t mode);
ssize_t Read(int fd, void *buf, size_t count);
ssize_t Write(int fd, const void *buf, size_t count);
off_t Lseek(int fildes, off_t offset, int whence);
void Close(int fd);
int Select(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
struct timeval *timeout);
int Dup2(int fd1, int fd2);
void Stat(const char *filename, struct stat *buf);
void Fstat(int fd, struct stat *buf) ;
/* Directory wrappers */
DIR *Opendir(const char *name);
struct dirent *Readdir(DIR *dirp);
int Closedir(DIR *dirp);
/* Memory mapping wrappers */
void *Mmap(void *addr, size_t len, int prot, int flags, int fd, off_t offset);
void Munmap(void *start, size_t length);
/* Standard I/O wrappers */
void Fclose(FILE *fp);
FILE *Fdopen(int fd, const char *type);
char *Fgets(char *ptr, int n, FILE *stream);
FILE *Fopen(const char *filename, const char *mode);
void Fputs(const char *ptr, FILE *stream);
size_t Fread(void *ptr, size_t size, size_t nmemb, FILE *stream);
void Fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);
/* Dynamic storage allocation wrappers */
void *Malloc(size_t size);
void *Realloc(void *ptr, size_t size);
void *Calloc(size_t nmemb, size_t size);
void Free(void *ptr);
/* Sockets interface wrappers */
int Socket(int domain, int type, int protocol);
void Setsockopt(int s, int level, int optname, const void *optval, int optlen);
void Bind(int sockfd, struct sockaddr *my_addr, int addrlen);
void Listen(int s, int backlog);
int Accept(int s, struct sockaddr *addr, socklen_t *addrlen);
void Connect(int sockfd, struct sockaddr *serv_addr, int addrlen);
/* Protocol independent wrappers */
void Getaddrinfo(const char *node, const char *service,
const struct addrinfo *hints, struct addrinfo **res);
void Getnameinfo(const struct sockaddr *sa, socklen_t salen, char *host,
size_t hostlen, char *serv, size_t servlen, int flags);
void Freeaddrinfo(struct addrinfo *res);
void Inet_ntop(int af, const void *src, char *dst, socklen_t size);
void Inet_pton(int af, const char *src, void *dst);
/* DNS wrappers */
struct hostent *Gethostbyname(const char *name);
struct hostent *Gethostbyaddr(const char *addr, int len, int type);
/* Pthreads thread control wrappers */
void Pthread_create(pthread_t *tidp, pthread_attr_t *attrp,
void * (*routine)(void *), void *argp);
void Pthread_join(pthread_t tid, void **thread_return);
void Pthread_cancel(pthread_t tid);
void Pthread_detach(pthread_t tid);
void Pthread_exit(void *retval);
pthread_t Pthread_self(void);
void Pthread_once(pthread_once_t *once_control, void (*init_function)());
/* POSIX semaphore wrappers */
void Sem_init(sem_t *sem, int pshared, unsigned int value);
void P(sem_t *sem);
void V(sem_t *sem);
/* Rio (Robust I/O) package */
ssize_t rio_readn(int fd, void *usrbuf, size_t n);
ssize_t rio_writen(int fd, void *usrbuf, size_t n);
void rio_readinitb(rio_t *rp, int fd);
ssize_t rio_readnb(rio_t *rp, void *usrbuf, size_t n);
ssize_t rio_readlineb(rio_t *rp, void *usrbuf, size_t maxlen);
/* Wrappers for Rio package */
ssize_t Rio_readn(int fd, void *usrbuf, size_t n);
void Rio_writen(int fd, void *usrbuf, size_t n);
void Rio_readinitb(rio_t *rp, int fd);
ssize_t Rio_readnb(rio_t *rp, void *usrbuf, size_t n);
ssize_t Rio_readlineb(rio_t *rp, void *usrbuf, size_t maxlen);
/* Reentrant protocol-independent client/server helpers */
int open_clientfd(char *hostname, char *port);
int open_listenfd(char *port);
/* Wrappers for reentrant protocol-independent client/server helpers */
int Open_clientfd(char *hostname, char *port);
int Open_listenfd(char *port);
#endif /* __CSAPP_H__ */
/* $end csapp.h */```
评论
0赞
Eugene Sh.
3/18/2021
请编辑您的问题并将此信息添加到其中。
0赞
bf3019
3/18/2021
好吧，我刚刚注册了 Stackoverflow，你们对我的问题表达方式简直是粗鲁无礼。我只是在学习这个系统！给我一些松弛！
0赞
mediocrevegetable1
3/19/2021
@bf3019我相信，当您单击按钮回答自己的问题时，会弹出一个弹出窗口警告您，如果您需要向问题添加任何信息，请对其进行编辑，不要发布答案（这样说是因为我几乎完成了您现在正在做的事情）。此外，我在这里没有看到任何粗鲁或尖刻的评论，这似乎是侮辱性的，毕竟人们正试图帮助你解决你的问题。我们只需要以正确的方式显示所有信息，并知道从哪里开始寻找错误（您在这几篇文章中发布了很多代码）来提供帮助。
0赞
M Oehm
3/19/2021
没有冒犯，但你发布了一大堆代码，真的是一个完整的项目。完全不清楚（对我们来说，一目了然）一切都是如何相互联系的。在屏幕截图中，您只需从 shell 调用，因此问题就在那里。请尽量将问题简化到那个小案例。sleeper
-1赞
bf3019
3/18/2021
#2
csapp.c：
* csapp.c
*/
/* $begin csapp.c */
#include "csapp.h"
/**************************
* Error-handling functions
**************************/
/* $begin errorfuns */
/* $begin unixerror */
void unix_error(char *msg) /* Unix-style error */
{
fprintf(stderr, "%s: %s\n", msg, strerror(errno));
exit(0);
}
/* $end unixerror */
void posix_error(int code, char *msg) /* Posix-style error */
{
fprintf(stderr, "%s: %s\n", msg, strerror(code));
exit(0);
}
void gai_error(int code, char *msg) /* Getaddrinfo-style error */
{
fprintf(stderr, "%s: %s\n", msg, gai_strerror(code));
exit(0);
}
void app_error(char *msg) /* Application error */
{
fprintf(stderr, "%s\n", msg);
exit(0);
}
/* $end errorfuns */
void dns_error(char *msg) /* Obsolete gethostbyname error */
{
fprintf(stderr, "%s\n", msg);
exit(0);
}
/*********************************************
* Wrappers for Unix process control functions
********************************************/
/* $begin forkwrapper */
pid_t Fork(void)
{
pid_t pid;
if ((pid = fork()) < 0)
unix_error("Fork error");
return pid;
}
/* $end forkwrapper */
void Execve(const char *filename, char *const argv[], char *const envp[])
{
if (execve(filename, argv, envp) < 0)
unix_error("Execve error");
}
/* $begin wait */
pid_t Wait(int *status)
{
pid_t pid;
if ((pid = wait(status)) < 0)
unix_error("Wait error");
return pid;
}
/* $end wait */
pid_t Waitpid(pid_t pid, int *iptr, int options)
{
pid_t retpid;
if ((retpid = waitpid(pid, iptr, options)) < 0)
unix_error("Waitpid error");
return(retpid);
}
/* $begin kill */
void Kill(pid_t pid, int signum)
{
int rc;
if ((rc = kill(pid, signum)) < 0)
unix_error("Kill error");
}
/* $end kill */
void Pause()
{
(void)pause();
return;
}
unsigned int Sleep(unsigned int secs)
{
unsigned int rc;
if ((rc = sleep(secs)) < 0)
unix_error("Sleep error");
return rc;
}
unsigned int Alarm(unsigned int seconds) {
return alarm(seconds);
}
void Setpgid(pid_t pid, pid_t pgid) {
int rc;
if ((rc = setpgid(pid, pgid)) < 0)
unix_error("Setpgid error");
return;
}
pid_t Getpgrp(void) {
return getpgrp();
}
/************************************
* Wrappers for Unix signal functions
***********************************/
/* $begin sigaction */
handler_t *Signal(int signum, handler_t *handler)
{
struct sigaction action, old_action;
action.sa_handler = handler;
sigemptyset(&action.sa_mask); /* Block sigs of type being handled */
action.sa_flags = SA_RESTART; /* Restart syscalls if possible */
if (sigaction(signum, &action, &old_action) < 0)
unix_error("Signal error");
return (old_action.sa_handler);
}
/* $end sigaction */
void Sigprocmask(int how, const sigset_t *set, sigset_t *oldset)
{
if (sigprocmask(how, set, oldset) < 0)
unix_error("Sigprocmask error");
return;
}
void Sigemptyset(sigset_t *set)
{
if (sigemptyset(set) < 0)
unix_error("Sigemptyset error");
return;
}
void Sigfillset(sigset_t *set)
{
if (sigfillset(set) < 0)
unix_error("Sigfillset error");
return;
}
void Sigaddset(sigset_t *set, int signum)
{
if (sigaddset(set, signum) < 0)
unix_error("Sigaddset error");
return;
}
void Sigdelset(sigset_t *set, int signum)
{
if (sigdelset(set, signum) < 0)
unix_error("Sigdelset error");
return;
}
int Sigismember(const sigset_t *set, int signum)
{
int rc;
if ((rc = sigismember(set, signum)) < 0)
unix_error("Sigismember error");
return rc;
}
int Sigsuspend(const sigset_t *set)
{
int rc = sigsuspend(set); /* always returns -1 */
if (errno != EINTR)
unix_error("Sigsuspend error");
return rc;
}
/*************************************************************
* The Sio (Signal-safe I/O) package - simple reentrant output
* functions that are safe for signal handlers.
*************************************************************/
/* Private sio functions */
/* $begin sioprivate */
/* sio_reverse - Reverse a string (from K&R) */
static void sio_reverse(char s[])
{
int c, i, j;
for (i = 0, j = strlen(s)-1; i < j; i++, j--) {
c = s[i];
s[i] = s[j];
s[j] = c;
}
}
/* sio_ltoa - Convert long to base b string (from K&R) */
static void sio_ltoa(long v, char s[], int b)
{
int c, i = 0;
int neg = v < 0;
if (neg)
v = -v;
do {
s[i++] = ((c = (v % b)) < 10) ? c + '0' : c - 10 + 'a';
} while ((v /= b) > 0);
if (neg)
s[i++] = '-';
s[i] = '\0';
sio_reverse(s);
}
/* sio_strlen - Return length of string (from K&R) */
static size_t sio_strlen(char s[])
{
int i = 0;
while (s[i] != '\0')
++i;
return i;
}
/* $end sioprivate */
/* Public Sio functions */
/* $begin siopublic */
ssize_t sio_puts(char s[]) /* Put string */
{
return write(STDOUT_FILENO, s, sio_strlen(s)); //line:csapp:siostrlen
}
ssize_t sio_putl(long v) /* Put long */
{
char s[128];
sio_ltoa(v, s, 10); /* Based on K&R itoa() */ //line:csapp:sioltoa
return sio_puts(s);
}
void sio_error(char s[]) /* Put error message and exit */
{
sio_puts(s);
_exit(1); //line:csapp:sioexit
}
/* $end siopublic */
/*******************************
* Wrappers for the SIO routines
******************************/
ssize_t Sio_putl(long v)
{
ssize_t n;
if ((n = sio_putl(v)) < 0)
sio_error("Sio_putl error");
return n;
}
ssize_t Sio_puts(char s[])
{
ssize_t n;
if ((n = sio_puts(s)) < 0)
sio_error("Sio_puts error");
return n;
}
void Sio_error(char s[])
{
sio_error(s);
}
/********************************
* Wrappers for Unix I/O routines
********************************/
int Open(const char *pathname, int flags, mode_t mode)
{
int rc;
if ((rc = open(pathname, flags, mode)) < 0)
unix_error("Open error");
return rc;
}
ssize_t Read(int fd, void *buf, size_t count)
{
ssize_t rc;
if ((rc = read(fd, buf, count)) < 0)
unix_error("Read error");
return rc;
}
ssize_t Write(int fd, const void *buf, size_t count)
{
ssize_t rc;
if ((rc = write(fd, buf, count)) < 0)
unix_error("Write error");
return rc;
}
off_t Lseek(int fildes, off_t offset, int whence)
{
off_t rc;
if ((rc = lseek(fildes, offset, whence)) < 0)
unix_error("Lseek error");
return rc;
}
void Close(int fd)
{
int rc;
if ((rc = close(fd)) < 0)
unix_error("Close error");
}
int Select(int n, fd_set *readfds, fd_set *writefds,
fd_set *exceptfds, struct timeval *timeout)
{
int rc;
if ((rc = select(n, readfds, writefds, exceptfds, timeout)) < 0)
unix_error("Select error");
return rc;
}
int Dup2(int fd1, int fd2)
{
int rc;
if ((rc = dup2(fd1, fd2)) < 0)
unix_error("Dup2 error");
return rc;
}
void Stat(const char *filename, struct stat *buf)
{
if (stat(filename, buf) < 0)
unix_error("Stat error");
}
void Fstat(int fd, struct stat *buf)
{
if (fstat(fd, buf) < 0)
unix_error("Fstat error");
}
/*********************************
* Wrappers for directory function
*********************************/
DIR *Opendir(const char *name)
{
DIR *dirp = opendir(name);
if (!dirp)
unix_error("opendir error");
return dirp;
}
struct dirent *Readdir(DIR *dirp)
{
struct dirent *dep;
errno = 0;
dep = readdir(dirp);
if ((dep == NULL) && (errno != 0))
unix_error("readdir error");
return dep;
}
int Closedir(DIR *dirp)
{
int rc;
if ((rc = closedir(dirp)) < 0)
unix_error("closedir error");
return rc;
}
/***************************************
* Wrappers for memory mapping functions
***************************************/
void *Mmap(void *addr, size_t len, int prot, int flags, int fd, off_t offset)
{
void *ptr;
if ((ptr = mmap(addr, len, prot, flags, fd, offset)) == ((void *) -1))
unix_error("mmap error");
return(ptr);
}
void Munmap(void *start, size_t length)
{
if (munmap(start, length) < 0)
unix_error("munmap error");
}
/***************************************************
* Wrappers for dynamic storage allocation functions
***************************************************/
void *Malloc(size_t size)
{
void *p;
if ((p = malloc(size)) == NULL)
unix_error("Malloc error");
return p;
}
void *Realloc(void *ptr, size_t size)
{
void *p;
if ((p = realloc(ptr, size)) == NULL)
unix_error("Realloc error");
return p;
}
void *Calloc(size_t nmemb, size_t size)
{
void *p;
if ((p = calloc(nmemb, size)) == NULL)
unix_error("Calloc error");
return p;
}
void Free(void *ptr)
{
free(ptr);
}
/******************************************
* Wrappers for the Standard I/O functions.
******************************************/
void Fclose(FILE *fp)
{
if (fclose(fp) != 0)
unix_error("Fclose error");
}
FILE *Fdopen(int fd, const char *type)
{
FILE *fp;
if ((fp = fdopen(fd, type)) == NULL)
unix_error("Fdopen error");
return fp;
}
char *Fgets(char *ptr, int n, FILE *stream)
{
char *rptr;
if (((rptr = fgets(ptr, n, stream)) == NULL) && ferror(stream))
app_error("Fgets error");
return rptr;
}
FILE *Fopen(const char *filename, const char *mode)
{
FILE *fp;
if ((fp = fopen(filename, mode)) == NULL)
unix_error("Fopen error");
return fp;
}
void Fputs(const char *ptr, FILE *stream)
{
if (fputs(ptr, stream) == EOF)
unix_error("Fputs error");
}
size_t Fread(void *ptr, size_t size, size_t nmemb, FILE *stream)
{
size_t n;
if (((n = fread(ptr, size, nmemb, stream)) < nmemb) && ferror(stream))
unix_error("Fread error");
return n;
}
void Fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream)
{
if (fwrite(ptr, size, nmemb, stream) < nmemb)
unix_error("Fwrite error");
}
/****************************
* Sockets interface wrappers
****************************/
int Socket(int domain, int type, int protocol)
{
int rc;
if ((rc = socket(domain, type, protocol)) < 0)
unix_error("Socket error");
return rc;
}
void Setsockopt(int s, int level, int optname, const void *optval, int optlen)
{
int rc;
if ((rc = setsockopt(s, level, optname, optval, optlen)) < 0)
unix_error("Setsockopt error");
}
void Bind(int sockfd, struct sockaddr *my_addr, int addrlen)
{
int rc;
if ((rc = bind(sockfd, my_addr, addrlen)) < 0)
unix_error("Bind error");
}
void Listen(int s, int backlog)
{
int rc;
if ((rc = listen(s, backlog)) < 0)
unix_error("Listen error");
}
int Accept(int s, struct sockaddr *addr, socklen_t *addrlen)
{
int rc;
if ((rc = accept(s, addr, addrlen)) < 0)
unix_error("Accept error");
return rc;
}
void Connect(int sockfd, struct sockaddr *serv_addr, int addrlen)
{
int rc;
if ((rc = connect(sockfd, serv_addr, addrlen)) < 0)
unix_error("Connect error");
}
/*******************************
* Protocol-independent wrappers
*******************************/
/* $begin getaddrinfo */
void Getaddrinfo(const char *node, const char *service,
const struct addrinfo *hints, struct addrinfo **res)
{
int rc;
if ((rc = getaddrinfo(node, service, hints, res)) != 0)
gai_error(rc, "Getaddrinfo error");
}
/* $end getaddrinfo */
void Getnameinfo(const struct sockaddr *sa, socklen_t salen, char *host,
size_t hostlen, char *serv, size_t servlen, int flags)
{
int rc;
if ((rc = getnameinfo(sa, salen, host, hostlen, serv,
servlen, flags)) != 0)
gai_error(rc, "Getnameinfo error");
}
void Freeaddrinfo(struct addrinfo *res)
{
freeaddrinfo(res);
}
void Inet_ntop(int af, const void *src, char *dst, socklen_t size)
{
if (!inet_ntop(af, src, dst, size))
unix_error("Inet_ntop error");
}
void Inet_pton(int af, const char *src, void *dst)
{
int rc;
rc = inet_pton(af, src, dst);
if (rc == 0)
app_error("inet_pton error: invalid dotted-decimal address");
else if (rc < 0)
unix_error("Inet_pton error");
}
/*******************************************
* DNS interface wrappers.
*
* NOTE: These are obsolete because they are not thread safe. Use
* getaddrinfo and getnameinfo instead
***********************************/
/* $begin gethostbyname */
struct hostent *Gethostbyname(const char *name)
{
struct hostent *p;
if ((p = gethostbyname(name)) == NULL)
dns_error("Gethostbyname error");
return p;
}
/* $end gethostbyname */
struct hostent *Gethostbyaddr(const char *addr, int len, int type)
{
struct hostent *p;
if ((p = gethostbyaddr(addr, len, type)) == NULL)
dns_error("Gethostbyaddr error");
return p;
}
/************************************************
* Wrappers for Pthreads thread control functions
************************************************/
void Pthread_create(pthread_t *tidp, pthread_attr_t *attrp,
void * (*routine)(void *), void *argp)
{
int rc;
if ((rc = pthread_create(tidp, attrp, routine, argp)) != 0)
posix_error(rc, "Pthread_create error");
}
void Pthread_cancel(pthread_t tid) {
int rc;
if ((rc = pthread_cancel(tid)) != 0)
posix_error(rc, "Pthread_cancel error");
}
void Pthread_join(pthread_t tid, void **thread_return) {
int rc;
if ((rc = pthread_join(tid, thread_return)) != 0)
posix_error(rc, "Pthread_join error");
}
/* $begin detach */
void Pthread_detach(pthread_t tid) {
int rc;
if ((rc = pthread_detach(tid)) != 0)
posix_error(rc, "Pthread_detach error");
}
/* $end detach */
void Pthread_exit(void *retval) {
pthread_exit(retval);
}
pthread_t Pthread_self(void) {
return pthread_self();
}
void Pthread_once(pthread_once_t *once_control, void (*init_function)()) {
pthread_once(once_control, init_function);
}
/*******************************
* Wrappers for Posix semaphores
*******************************/
void Sem_init(sem_t *sem, int pshared, unsigned int value)
{
if (sem_init(sem, pshared, value) < 0)
unix_error("Sem_init error");
}
void P(sem_t *sem)
{
if (sem_wait(sem) < 0)
unix_error("P error");
}
void V(sem_t *sem)
{
if (sem_post(sem) < 0)
unix_error("V error");
}
/****************************************
* The Rio package - Robust I/O functions
****************************************/
/*
* rio_readn - Robustly read n bytes (unbuffered)
*/
/* $begin rio_readn */
ssize_t rio_readn(int fd, void *usrbuf, size_t n)
{
size_t nleft = n;
ssize_t nread;
char *bufp = usrbuf;
while (nleft > 0) {
if ((nread = read(fd, bufp, nleft)) < 0) {
if (errno == EINTR) /* Interrupted by sig handler return */
nread = 0; /* and call read() again */
else
return -1; /* errno set by read() */
}
else if (nread == 0)
break; /* EOF */
nleft -= nread;
bufp += nread;
}
return (n - nleft); /* Return >= 0 */
}
/* $end rio_readn */
/*
* rio_writen - Robustly write n bytes (unbuffered)
*/
/* $begin rio_writen */
ssize_t rio_writen(int fd, void *usrbuf, size_t n)
{
size_t nleft = n;
ssize_t nwritten;
char *bufp = usrbuf;
while (nleft > 0) {
if ((nwritten = write(fd, bufp, nleft)) <= 0) {
if (errno == EINTR) /* Interrupted by sig handler return */
nwritten = 0; /* and call write() again */
else
return -1; /* errno set by write() */
}
nleft -= nwritten;
bufp += nwritten;
}
return n;
}
/* $end rio_writen */
/*
* rio_read - This is a wrapper for the Unix read() function that
* transfers min(n, rio_cnt) bytes from an internal buffer to a user
* buffer, where n is the number of bytes requested by the user and
* rio_cnt is the number of unread bytes in the internal buffer. On
* entry, rio_read() refills the internal buffer via a call to
* read() if the internal buffer is empty.
*/
/* $begin rio_read */
static ssize_t rio_read(rio_t *rp, char *usrbuf, size_t n)
{
int cnt;
while (rp->rio_cnt <= 0) { /* Refill if buf is empty */
rp->rio_cnt = read(rp->rio_fd, rp->rio_buf,
sizeof(rp->rio_buf));
if (rp->rio_cnt < 0) {
if (errno != EINTR) /* Interrupted by sig handler return */
return -1;
}
else if (rp->rio_cnt == 0) /* EOF */
return 0;
else
rp->rio_bufptr = rp->rio_buf; /* Reset buffer ptr */
}
/* Copy min(n, rp->rio_cnt) bytes from internal buf to user buf */
cnt = n;
if (rp->rio_cnt < n)
cnt = rp->rio_cnt;
memcpy(usrbuf, rp->rio_bufptr, cnt);
rp->rio_bufptr += cnt;
rp->rio_cnt -= cnt;
return cnt;
}
/* $end rio_read */
/*
* rio_readinitb - Associate a descriptor with a read buffer and reset buffer
*/
/* $begin rio_readinitb */
void rio_readinitb(rio_t *rp, int fd)
{
rp->rio_fd = fd;
rp->rio_cnt = 0;
rp->rio_bufptr = rp->rio_buf;
}
/* $end rio_readinitb */
/*
* rio_readnb - Robustly read n bytes (buffered)
*/
/* $begin rio_readnb */
ssize_t rio_readnb(rio_t *rp, void *usrbuf, size_t n)
{
size_t nleft = n;
ssize_t nread;
char *bufp = usrbuf;
while (nleft > 0) {
if ((nread = rio_read(rp, bufp, nleft)) < 0)
return -1; /* errno set by read() */
else if (nread == 0)
break; /* EOF */
nleft -= nread;
bufp += nread;
}
return (n - nleft); /* return >= 0 */
}
/* $end rio_readnb */
/*
* rio_readlineb - Robustly read a text line (buffered)
*/
/* $begin rio_readlineb */
ssize_t rio_readlineb(rio_t *rp, void *usrbuf, size_t maxlen)
{
int n, rc;
char c, *bufp = usrbuf;
for (n = 1; n < maxlen; n++) {
if ((rc = rio_read(rp, &c, 1)) == 1) {
*bufp++ = c;
if (c == '\n') {
n++;
break;
}
} else if (rc == 0) {
if (n == 1)
return 0; /* EOF, no data read */
else
break; /* EOF, some data was read */
} else
return -1; /* Error */
}
*bufp = 0;
return n-1;
}
/* $end rio_readlineb */
/**********************************
* Wrappers for robust I/O routines
**********************************/
ssize_t Rio_readn(int fd, void *ptr, size_t nbytes)
{
ssize_t n;
if ((n = rio_readn(fd, ptr, nbytes)) < 0)
unix_error("Rio_readn error");
return n;
}
void Rio_writen(int fd, void *usrbuf, size_t n)
{
if (rio_writen(fd, usrbuf, n) != n)
unix_error("Rio_writen error");
}
void Rio_readinitb(rio_t *rp, int fd)
{
rio_readinitb(rp, fd);
}
ssize_t Rio_readnb(rio_t *rp, void *usrbuf, size_t n)
{
ssize_t rc;
if ((rc = rio_readnb(rp, usrbuf, n)) < 0)
unix_error("Rio_readnb error");
return rc;
}
ssize_t Rio_readlineb(rio_t *rp, void *usrbuf, size_t maxlen)
{
ssize_t rc;
if ((rc = rio_readlineb(rp, usrbuf, maxlen)) < 0)
unix_error("Rio_readlineb error");
return rc;
}
/********************************
* Client/server helper functions
********************************/
/*
* open_clientfd - Open connection to server at <hostname, port> and
* return a socket descriptor ready for reading and writing. This
* function is reentrant and protocol-independent.
*
* On error, returns:
* -2 for getaddrinfo error
* -1 with errno set for other errors.
*/
/* $begin open_clientfd */
int open_clientfd(char *hostname, char *port) {
int clientfd, rc;
struct addrinfo hints, *listp, *p;
/* Get a list of potential server addresses */
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_socktype = SOCK_STREAM; /* Open a connection */
hints.ai_flags = AI_NUMERICSERV; /* ... using a numeric port arg. */
hints.ai_flags |= AI_ADDRCONFIG; /* Recommended for connections */
if ((rc = getaddrinfo(hostname, port, &hints, &listp)) != 0) {
fprintf(stderr, "getaddrinfo failed (%s:%s): %s\n", hostname, port, gai_strerror(rc));
return -2;
}
/* Walk the list for one that we can successfully connect to */
for (p = listp; p; p = p->ai_next) {
/* Create a socket descriptor */
if ((clientfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) < 0)
continue; /* Socket failed, try the next */
/* Connect to the server */
if (connect(clientfd, p->ai_addr, p->ai_addrlen) != -1)
break; /* Success */
if (close(clientfd) < 0) { /* Connect failed, try another */ //line:netp:openclientfd:closefd
fprintf(stderr, "open_clientfd: close failed: %s\n", strerror(errno));
return -1;
}
}
/* Clean up */
freeaddrinfo(listp);
if (!p) /* All connects failed */
return -1;
else /* The last connect succeeded */
return clientfd;
}
/* $end open_clientfd */
/*
* open_listenfd - Open and return a listening socket on port. This
* function is reentrant and protocol-independent.
*
* On error, returns:
* -2 for getaddrinfo error
* -1 with errno set for other errors.
*/
/* $begin open_listenfd */
int open_listenfd(char *port)
{
struct addrinfo hints, *listp, *p;
int listenfd, rc, optval=1;
/* Get a list of potential server addresses */
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_socktype = SOCK_STREAM; /* Accept connections */
hints.ai_flags = AI_PASSIVE | AI_ADDRCONFIG; /* ... on any IP address */
hints.ai_flags |= AI_NUMERICSERV; /* ... using port number */
if ((rc = getaddrinfo(NULL, port, &hints, &listp)) != 0) {
fprintf(stderr, "getaddrinfo failed (port %s): %s\n", port, gai_strerror(rc));
return -2;
}
/* Walk the list for one that we can bind to */
for (p = listp; p; p = p->ai_next) {
/* Create a socket descriptor */
if ((listenfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) < 0)
continue; /* Socket failed, try the next */
/* Eliminates "Address already in use" error from bind */
setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, //line:netp:csapp:setsockopt
(const void *)&optval , sizeof(int));
/* Bind the descriptor to the address */
if (bind(listenfd, p->ai_addr, p->ai_addrlen) == 0)
break; /* Success */
if (close(listenfd) < 0) { /* Bind failed, try the next */
fprintf(stderr, "open_listenfd close failed: %s\n", strerror(errno));
return -1;
}
}
/* Clean up */
freeaddrinfo(listp);
if (!p) /* No address worked */
return -1;
/* Make it a listening socket ready to accept connection requests */
if (listen(listenfd, LISTENQ) < 0) {
close(listenfd);
return -1;
}
return listenfd;
}
/* $end open_listenfd */
/****************************************************
* Wrappers for reentrant protocol-independent helpers
****************************************************/
int Open_clientfd(char *hostname, char *port)
{
int rc;
if ((rc = open_clientfd(hostname, port)) < 0)
unix_error("Open_clientfd error");
return rc;
}
int Open_listenfd(char *port)
{
int rc;
if ((rc = open_listenfd(port)) < 0)
unix_error("Open_listenfd error");
return rc;
}
/* $end csapp.c */
0赞
bf3019
3/18/2021
#3
Sleeper.c：
/*
* sleeper.c
*/
/*
* Get csapp.h and csapp.c from http://csapp.cs.cmu.edu/3e/code.html
*
* $ gcc sleeper.c csapp.c -o sleeper
*
* (Ignore any compliation warnings related to code in csapp.c.)
*
* $ ./sleeper
*
* ... CTRL-C to terminate and see message indicating sleeper
* caught SIGINT. CTRL-Z to stop and see message indicating
* sleeper caught SIGTSTP. "jobs" to see list of stopped jobs
* with numerical IDs (including ./sleeper). "fg %1" to restart
* job with ID 1 (i.e., sleeper) and see message indicating
* sleeper caught SIGCONT.
*/
#include "csapp.h"
int pid;
pid_t fg_pid;
void sigint_handler(int signal) {
// Restore default behavior for next SIGINT (which will likely
// come from call to raise at the end of this function).
Signal(SIGINT, SIG_DFL);
printf("\nsleeper (%d) caught SIGINT\n", pid);
// Send SIGINT to self. (This time won't be caught be handler,
// will instead cause process to terminate.)
raise(SIGINT);
}
void sigtstp_handler(int signal) {
// Restore default behavior for next SIGTSTP ...
Signal(SIGTSTP, SIG_DFL);
printf("\nsleeper (%d) caught SIGTSTP\n", pid);
// Send SIGTSTP to self ...
raise(SIGTSTP);
}
void sigcont_handler(int signal) {
// Don't need to restore default behavior of SIGCONT, because
// default (for already running process) is to ignore it.
// Prepare for next SIGTSTP signal.
Signal(SIGTSTP, sigtstp_handler);
printf("\nsleeper (%d) caught SIGCONT\n", pid);
// Don't need to raise SIGCONT, because process is already
// running (and would ignore it).
}
// First command line argument is number of times to sleep. (0
// or no argument means to continue indefinitely.) Second argument
// -q for quiet sleeper.
int main(int argc, char **argv) {
int i, n, q;
n = argc > 1 ? atoi(argv[1]) : 0;
q = argc > 2 && strcmp("-q", argv[2]) == 0;
pid = getpid();
// Override default behavior for SIGINT, SIGTSTP and SIGCONT.
Signal(SIGINT, sigint_handler);
Signal(SIGTSTP, sigtstp_handler);
Signal(SIGCONT, sigcont_handler);
// Sleep 1 second, wake up, go back to sleep...
for (i = 0; n == 0 || i < n; i++) {
Sleep(1);
if (!q) {
printf("sleeper (%d) slept %d second(s)\n", pid, i + 1);
}
}
return 0;
}
1赞
wildplasser
3/19/2021
#4
- 不要使用或在阅读他们的手册页之前
strndup()strncpy() - [使用手册页后，您无论如何都不会使用它们]
- 不要在信号处理程序中使用 and;它们不是信号安全的。
printf()
评论
stdlib.hgcc -Wall -Wextra -g