Some loose ends

This is a discussion on Some loose ends within the C Programming forums, part of the General Programming Boards category; Please read the following long commented piece of code. Code: /*This program will scan through a directory if it finds ...

  1. #1
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    Some loose ends

    Please read the following long commented piece of code.

    Code:
    /*This program will scan through a directory
     if it finds subdirectories within it, it will
     check if the name of the directory is a digit
     if it is it will return 1, otherwise a 0. Based
     upon the return value, the program will print the
     details of the process that was matched (a match 
     being a 1). These details are obtained by opening
     a file stream to the processes stat file, and then
     scanning through the details using the fscanf function.
     This program is in essence a mimmick of the ps command. 
    
     Fortunately there are only a few things to iron out now
     here goes. 
     1. When the processes and their details get printed out
        they are not in order. I can't say i really understand
        why this doesn't happen as this line in main should 
        perform this task
    
        count = scandir(path,&direntp,NULL,alphasort);
    
     2. The tty that the process uses seems to report back
        incorecctly, infact the only one it seems to recognise
        is pts/0 it never once mentions ttyx (where x is a number),
        Also some of the time it comes back as null, where as if
        I use the ps command normally those that are null in my version
        have value in the proper version. Here are the lines associated
        with tty.
    
        t_name = ttyname(tty);
        if(t_name == NULL)
          t_name = "?";
    
     3. Getting the run time of the process is not always succesful,
        for example it sometimes gives the correct output such as
        00:00:05 (Hours,Minutes,Seconds). But some of the time it prints
        garble instead eg.
    
        h-@h-@
    
        This seems to suggest to me that the variable time hasn't been assigned
        any value and is just printing non-sense, where as it can be clearly
        seen that this is not the case.
    
        time = getTime(stime);
    
     4. I suppose while i'm asking stuff I might aswell ask for ideas on implementing
        "ps -A" which basically prints all the current processes, not those just
        belonging to the user. Would this involve use of the getuid method??   
    
        */
    
    #include <stdio.h>
    #include <sys/types.h>
    #include <fcntl.h>
    #include <dirent.h>
    #include <stdlib.h>
    #include <sys/stat.h>
    #include <regex.h>
    #include <unistd.h>
    
    #define SIZE 256
    
    /*prototypes*/
    int matchDetails(char* filename,char* path);
    void printDetails(char* filename,char* path);
    char* getTime(int clockticks);
    char *get_regerror(int errcode,regex_t *compiled);
    
    int main(void){
      int result,count,index;   /*Set Conditions*/
      char path[] = "/proc";    /*Path to the proc directory*/
      struct dirent **direntp;  /*Directory entry pointer*/
      struct stat sbuf;         /*Holds information about files*/
    
      if (stat(path,&sbuf) != -1){
        if(S_ISDIR(sbuf.st_mode)){
           count = scandir(path,&direntp,NULL,alphasort);
           if(count){
             char temp[FILENAME_MAX];
             printf("PID      TTY         TIME      CMD\n");
             for(index=0; index<count; ++index){
               strcpy(temp,path);
               result = matchDetails(direntp[index]->d_name,temp);
               if(result > 0)   /*If directory name was matched*/
                 printDetails(direntp[index]->d_name,temp);
               free(direntp[index]);
             }
           }else{
             fprintf(stderr,"Can't open %s\n",path);
             exit(EXIT_FAILURE);
           }
        }else
          return;
      }else{
        fprintf(stderr,"Can't stat %s\n",path);
        return;
      } 
      return EXIT_SUCCESS;
    }
    
    /*Used to find process directories*/
    int matchDetails(char* filename,char* path){
      int status,regstat;
      char *pattern = "[0-9]+"; /*Match digits only*/
      char *result;
      struct stat sbuf;
    
      /*Get the full pathname*/
      strcat(path,"/");
      strcat(path,filename);
    
      /*Stat the full path name*/
      if(stat(path,&sbuf) != -1){
        if(S_ISDIR(sbuf.st_mode)){ /*If a directory*/
          regex_t re;
          if((regstat = regcomp(&re,pattern,REG_EXTENDED | REG_NOSUB)) != 0){
            result = get_regerror(regstat,&re);
            fprintf(stderr,"%s\n",result);
            return(0);
          }
          if((status = regexec(&re,filename,(size_t) 0,NULL,0)) != 0)
            return(0);
          regfree(&re);
        }else
          return(0);
      }else{
        fprintf(stderr,"Can't stat %s\n",filename);
        return(0);
      }
      return(1);
    
    }
    
    /*Print the process information*/
    void printDetails(char* filename,char* path){
      FILE *f_name;
      int pid,tty,stime;
      char pname[FILENAME_MAX];
      char* t_name;
      char* time;
    
      /*Format the path*/
      strcat(path,"/");
      strcat(path,"stat");
    
      if((f_name = fopen(path,"r")) != NULL){
        fscanf(f_name,"%d %s %*c %*d %*d %*d %d %*d 
               %*u %*u %*u %*u %*u %*d %d",&pid,&pname,&tty,&stime);
        t_name = ttyname(tty);
        time = getTime(stime); 
        if(t_name == NULL)
          t_name = "?";           
        printf("%-9d%-12s%-6s  %s\n",pid,t_name,time,pname);
        fclose(f_name);
      }else
        fprintf(stderr,"Can't open %s\n",path);
    
    }
    
    /*Format jiffies into hours,minutes,seconds*/
    char* getTime(int clockticks){
      float jiffies,result;
      int min,hr,seconds;
      char* time = (char*)malloc(SIZE);
    
      jiffies = 0.01f;
      
      result  = jiffies * clockticks;
      seconds = result;
      min     = seconds/60;
      hr      = min/60;
    
      seconds %= 60; /*MOD it into 0-59*/
      min     %= 60; /*MOD it into 0-59*/
    
      if(hr < 10 && min < 10 && seconds < 10)
        sprintf(time,"0%d:0%d:0%d",hr,min,seconds);
      else if(hr < 10 && min < 10)
        sprintf(time,"0%d:0%d:%d",hr,min,seconds);
      else if(hr < 10 && seconds < 10)
        sprintf(time,"0%d:%d:0%d",hr,min,seconds);
      else if(min < 10 && seconds < 10)
        sprintf(time,"%d:0%d:0%d",hr,min,seconds);
      else if(hr < 10)
        sprintf(time,"0%d:%d:%d",hr,min,seconds);
      else if(min < 10)
        sprintf(time,"%d:0%d:%d",hr,min,seconds);
      else if(seconds < 10)
        sprintf(time,"%d:%d:0%d",hr,min,seconds);
      else
        sprintf(time,"%d:%d:%d",hr,min,seconds);
      free(time); 
    
      return time;
    }
    
    /*Used to store regex errors*/
    char *get_regerror(int errcode,regex_t *compiled){
      size_t length = regerror(errcode,compiled,NULL,0);
      char *buffer = malloc(length);
      (void) regerror(errcode,compiled,buffer,length);
      return buffer;
    }
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  2. #2
    Code Warrior
    Join Date
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    669

    Thumbs up

    The first error is in your library definiton. Library "dirent.h" does not exist, but the library "direct.h" does exist.
    Current projects:
    1) User Interface Development Kit (C++)
    2) HTML SDK (C++)
    3) Classes (C++)
    4) INI Editor (Delphi)

  3. #3
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    Thats not an error, dirent.h does exist but only in unix/linux
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  4. #4
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    Wink

    Ups, sorry about that .
    Current projects:
    1) User Interface Development Kit (C++)
    2) HTML SDK (C++)
    3) Classes (C++)
    4) INI Editor (Delphi)

  5. #5
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    *bump* Comeon you linux gurus
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  6. #6
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    3. Getting the run time of the process is not always succesful,
    for example it sometimes gives the correct output such as
    00:00:05 (Hours,Minutes,Seconds). But some of the time it prints
    garble instead eg.

    h-@h-@

    This seems to suggest to me that the variable time hasn't been assigned
    any value and is just printing non-sense, where as it can be clearly
    seen that this is not the case.

    time = getTime(stime);
    in function getTime().

    could it be that you free time before you return it?
    Last edited by CtrlAltKick; 03-31-2002 at 02:10 PM.

  7. #7
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    Nah i tried commenting that out, still get the same problem.

    EDIT: Hmm could have sworn I tried that, obviously not, neway that seemed to work, oh well 1 down 3 to go
    Last edited by pdstatha; 03-31-2002 at 02:14 PM.
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  8. #8
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    I know why it isn't sorting now, it's cos it sorts alpabetically not numerically. I've looked up the man pages for the qsort, which is defined as the following.

    Code:
    void qsort(void *base, size_t nmemb, size_t size,
                 int (*compar)(const void *, const void *));
    I can't really make much sense of this, how would I implement this function for my purposes??
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