Linux命令实现（4） ls －l

使用了stat（）
终于实现读取文件的详细信息

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <dirent.h>
#include <sys/stat.h>
#include <pwd.h>
#include <grp.h>

void do_ls(char[]);
void dostat(char *);
void show_file_info(char *,struct stat *);
void mode_to_letters(int ,char[]);
char * uid_toi_letters(uid_t);
char * gid_to_name(gid_t);

int main(int argc, char *argv[])
{
if(argc==1)
{
do_ls(".");
}
else
while(--argc)
{
printf("%s:/n",*++argv);
do_ls(*argv);
}

return EXIT_SUCCESS;
}

void do_ls(char dirname[])
{
DIR *dir_ptr;
struct dirent *direntp;
if((dir_ptr=opendir(dirname))==NULL)
{
fprintf(stderr,"ls:cannot open %s/n",dirname);
}
else
{
while((direntp=readdir(dir_ptr))!=NULL)
do_stat(direntp->d_name);
closedir(dir_ptr);
}
}

void do_stat(char *filename)
{
struct stat info;
if(stat(filename,&info)==-1)
{
perror(filename);
}
else
show_file_info(filename,&info);
}

void show_file_info(char *filename,struct stat *info_p)
{
char *uid_to_name(),*ctime(),*gid_to_name(),*filemode();
void mode_to_letters();
char modestr[11];

mode_to_letters(info_p->st_mode,modestr);

printf("%s ",modestr);
printf("%4d ",(int)info_p->st_nlink);
printf("-8s ",uid_to_name(info_p->st_uid));
printf("-8s ",gid_to_name(info_p->st_gid));
printf("%8ld ",(long)info_p->st_size);
printf("%.12s ",4+ctime(&info_p->st_mtime));
printf("%s/n",filename);
}

void mode_to_letters(int mode,char str[])
{
strcpy(str,"----------");
if(S_ISDIR(mode))str[0]='d';
if(S_ISCHR(mode))str[0]='c';
if(S_ISBLK(mode))str[0]='b';

if(mode&S_IRUSR)str[1]='r';
if(mode&S_IWUSR)str[2]='w';
if(mode&S_IXUSR)str[3]='x';

if(mode&S_IRGRP)str[4]='r';
if(mode&S_IWGRP)str[5]='w';
if(mode&S_IXGRP)str[6]='x';

if(mode&S_IROTH)str[7]='r';
if(mode&S_IWOTH)str[8]='w';
if(mode&S_IXOTH)str[9]='x';

}

char *uid_to_name(uid_t uid)
{
struct passwd *getpwuid(),*pw_ptr;
static char numstr[10];

if((pw_ptr=getpwuid(uid))==NULL)
{
sprintf(numstr,"%d",uid);
return numstr;
}
else
return pw_ptr->pw_name;
}

char *gid_to_name(gid_t gid)
{
struct group *getgrgid(),*grp_ptr;
static char numstr[10];
if((grp_ptr=getgrgid(gid))==NULL)
{
sprintf(numstr,"%d",gid);
return numstr;
}
else
return grp_ptr->gr_name;
}