Simple implementation of Linux basic--LS functions

Simple LS implementation, first, we need to traverse the parameters directory under the various files, and then according to the nature of the file, read the permissions of the file, user group, user name, size, the last time to access, and then according to the name of the order displayed.

The specific function declarations are as follows:

1#include <stdio.h>2#include <stdlib.h>3#include <string.h>4#include <sys/stat.h>5#include <fcntl.h>6#include <unistd.h>7#include <dirent.h>8#include <sys/types.h>9#include <pwd.h>Ten#include <grp.h> One#include <time.h> A #defineCNT 256 - intfile_name (DIR *FP,Char*path,Charname[][cnt]); - voidStr_sort (CharNAME[][CNT],intCNT); the voidMode_to_char (mode_t mode,Char*buf); - Char*time_change (Char*Time ); - voidShowCharNAME[][CNT],intCNT);

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Directory traversal, we need to know the number of files read in the directory, so we need to return the corresponding int value.
The traversal of the directory is implemented as follows:

1 intfile_name (DIR *FP,Char*path,Charname[][cnt])2 {3     intCNT =0;4     structDirent *p;5      while((P = readdir (fp))! =NULL)6     {7         if(STRNCMP (P->d_name,".",1) ==0|| STRNCMP (P->d_name,"..",2) ==0)8             Continue;9 strcpy (name[cnt], path);TenStrcat (name[cnt],"/"); OneStrcat (name[cnt], p->d_name); ACNT + +; -     } - Closedir (FP); the     returnCNT; -}

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Then we need to understand the permissions of the file, and the file permissions are stored in the corresponding parameter char *buf.
The interpretation of file permissions is implemented as follows:

1 voidMode_to_char (mode_t mode,Char*buf)2 {3memset (BUF,'-',Ten);4     if(S_isdir (mode))5buf[0] ='D';6     if(Mode &s_irusr)7buf[1] ='R';8     if(Mode &s_iwusr)9buf[2] ='W';Ten     if(Mode &s_ixusr) Onebuf[3] ='x'; A     if(Mode &s_irgrp) -buf[4] ='R'; -     if(Mode &s_iwgrp) thebuf[5] ='W'; -     if(Mode &s_ixgrp) -buf[6] ='x'; -     if(Mode &S_iroth) +buf[7] ='R'; -     if(Mode &S_iwoth) +buf[8] ='W'; A     if(Mode &S_ixoth) atbuf[9] ='x'; -}

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To be expected, the time display does not need to be so precise, so we should shorten the time accuracy appropriately.
The display of time is implemented as follows:

1 Char*time_change (Char*Time )2 {3     intindex = strlen (time)-1;4      for(; Time[index]! =':'; Index--);5Time[index] =' /';6     returnTime +4;7}

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Then we need to sort by the dictionary order according to the file name.
The implementation of the sort is as follows:

1 voidStr_sort (CharNAME[][CNT],intCNT)2 {3     intindex, POS;4     Charstr[cnt];5      for(pos =1; POS < CNT; POS + +)6     {7 strcpy (str, name[pos]);8          for(index = pos-1; Index >=0; Index--)9             if(strcmp (Name[index], str) >0)Tenstrcpy (Name[index +1], Name[index]); One             Else A                  Break; -strcpy (Name[index +1], str); -     } the}

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Finally, we are writing a simple show () function to display the information for each file.

The show function is implemented as follows:

1 voidShowCharNAME[][CNT],intCNT)2 {3     intindex;4     Charmode[Ten];5     Char*str;6     structstat buf;7      for(index =0; Index < CNT; Index + +)8     {9memset (&buf,0,sizeof(BUF));Ten         if(Stat (Name[index], &buf) = =-1) One         { Aprintf"Stat error!! \ n"); -Exit1); -         } the Mode_to_char (buf.st_mode, mode); -str = CTime (&buf.st_atime); -str =Time_change (str); -         inti; +          for(i = strlen (Name[index])-1; Name[index][i]! ='/'; I--); -i++; +printf"%10s.%2d%5s%5s%5d%13s%s\n", mode, Buf.st_nlink, Getpwuid (buf.st_uid)->pw_name, Getgrgid (buf.st_gid)->gr_name, Buf.st_size, str, name[ Index] +i); A     } at}

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Here's what to note:

Getpwuid () is not returning the username we want, we need a variable--pw_name in the struct, and the same getgrid () should be converted accordingly.

The test code is as follows:

1#include"head.h"2 intMainintargcChar*argv[])3 {4DIR *FP;5     Charname[cnt][cnt];6     intCNT;7fp = Opendir (argv[1]);8     if(fp = =NULL)9     {Tenprintf"Opendir error!! \ n"); OneExit1); A     } -CNT = file_name (FP, argv[1], name); - str_sort (name, CNT); the Show (name, CNT); -     return 0; -}

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Simple implementation of Linux basic--ls features