求各位大神的解答，linux一个小程序的问题，至今仍困扰着我！
其实这个程序就是想实现ls -al 的功能 ，但遇到一个问题，让我迟迟没有解决，上代码吧，大家复制代码后试试？
1 #include<stdio.h>
2 #include<stdlib.h>
3 #include<unistd.h>
4 #include<sys/types.h>
5 #include<sys/stat.h>
6 #include<dirent.h>
7 #include<string.h>
8
9
10 #define N_BITS 3
11 #define MAX_PATH 80
12
13 void output_dir_info(const char *new_docunment);
14 void output_file_info(struct stat file);
15
16 int main(int argc,char **argv)
17 {
18 char *docunment_path;
19 docunment_path=(char *)malloc(sizeof(char)*MAX_PATH);
20 getcwd(docunment_path,MAX_PATH);
21 if(argc==1) //read current docunment
22 output_dir_info(docunment_path);
23 else if(argc==2) //panduan pramamter
24 {
25 struct stat stat_file;
26 stat(argv[1],&stat_file);
27 if(S_ISREG(stat_file.st_mode)) //a file
28 {
29 output_file_info(stat_file);
30 }
31 else if(S_ISDIR(stat_file.st_mode)) //a docunment
32 {
33 char *new_docunment;
34 new_docunment=(char *)malloc(sizeof(docunment_pa th)+1+sizeof(argv[1])+1);
35 sprintf(new_docunment,"%s/%s\0",docunment_path,a rgv[1]);
36 output_dir_info(new_docunment); //read dir
37 }
38 }
39 else //input error
40 {
41 fprintf(stderr,"Usage :%s [file_name or dir_name]\n",arg v[0]);
42 }
43
44 return 0;
45 }
46 void output_dir_info(const char *docunment) //read dir
47 {
48 DIR *dirp=NULL;
49 dirp=opendir(docunment);
51 struct dirent *entp=NULL;
52
53 while(NULL!=(entp=readdir(dirp)))
54 {
55 if(strcmp(entp->d_name,"..")==0||strcmp(entp->d_name,"." )==0)
56 {
57 continue;
58 }
59 char *file_path=(char *)malloc(sizeof(docunment)+1+sizeof(entp->d_name)+1);
60 sprintf(file_path,"%s/%s\0",docunment,entp->d_name);
61 struct stat stat_file;
62 stat(file_path,&stat_file);
63 output_file_info(stat_file);
64 }
65 }
66 void output_file_info(struct stat file) //print file
67 {
68 unsigned int i ,mask=0700;
69 unsigned num_temp;
70 static char *perm[]={"---","--x","-w-","-wx","r--","r-x","rw-"," rwx"};
71 for(i=3;i;i--)
72 {
73 num_temp=(file.st_mode&mask)>>(i-1)*N_BITS;
74 printf("%3s",perm[num_temp]);
75 mask>>=N_BITS;
76 }
77 printf("\t%d\t%d\t%ld\t%ld\n",file.st_nlink,file.st_uid,file.st_ size,file.st_atime);
78 }
程序运行时传递一个“目录”作为参数。 问题主要出在line47-line51，当运行到47行时，用gdb单步调试发现char *docunment = 当前的目录路径，但一到line51后，char *docunment的值就不对了？？一直没搞清是为什么？？ 求各位大神帮小弟一把！ 非常感谢
linux
[解决办法]
你59行分配的空间不足吧
char *file_path=(char *)malloc(sizeof(docunment)+1+sizeof(entp->d_name)+1);
那个sizeof(document)是指针本身的大小，通常是4
你这儿应该改为strlen(document)
