Linux programme - different results each run

[ulyses]

Hi i have got quite strange problem. I wrote programme which shows all
runnign processes. This info is get from /proc dir. When a dir that is
process dir is found stat file is read and pid, name and state are get
from it. The thing is that on my machine every time I run it, it gives
different results. Sometimes it shows nothing - most of the times.
Sometimes it shows info about 4 processes. Sometimes it works
correctly. I don't now whats wrong, I 've tried to find the mistake,
but I could'n. I begginer programmer and I don't know how to cope with
this problem. Please help me!

Here is the code:

 
 
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <dirent.h>
#include <stdlib.h>
 
int isNum(char );
int isProcDir(char * );
int showRunningProcesses();
 
int main()
{
 
showRunningProcesses();
 
return 0;
 
}
 
/*
 
Function indicates if char given in data variable is number.
If it is it returns 0. If it is not a number it returns 1.
 
*/
int isNum(char data)
{
 
switch(data)
{
case '0': return 0;
case '1': return 0;
case '2': return 0;
case '3': return 0;
case '4': return 0;
case '5': return 0;
case '6': return 0;
case '7': return 0;
case '8': return 0;
case '9': return 0;
default : return 1;
}
 
}
 
/*
 
Function indicates if char given by *path pointer
is process dir (in /proc file system). If it is it
returns 0. If it is not it returns 1.
 
*/
 
int isProcDir(char *path)
{
struct stat st;
int i;
int path_length;
 
lstat(path, &st);
path_length = strlen(path);
 
//printf("running.. %s\n", path);
//printf("%o", st.st_mode);
if (S_ISDIR(st.st_mode))
return 1;
else if(S_ISLNK(st.st_mode))
return 1;
else if(S_ISCHR(st.st_mode))
return 1;
else if(S_ISBLK(st.st_mode))
return 1;
else if(S_ISFIFO(st.st_mode))
return 1;
else if(S_ISSOCK(st.st_mode))
return 1;
else if(S_ISREG(st.st_mode))
return 1;
else
{
//printf("path: %s \n", path);
//fprintf(stderr, "found");
 
 
for(i=0; i<path_length; i++)
{
if (isNum(path[i]))
{
return 1;
}
}
 
return 0;
}
 
}
 
int showRunningProcesses()
{
 
int i;
DIR *directory, *process_directory;
FILE *fp;
struct dirent *dir_entry;
char *path = (char *)malloc(50);
char *name;
char pid[10], procName[15], state[5];
 
strcat(path,"/proc/");
 
if( ( directory=opendir(path) ) == NULL )
{
fprintf(stderr,    "Couldn't open /proc dir.");
return 1;
 
}
 
while(dir_entry=readdir(directory))
{
 
/*
Check if read directory is process
directory.
*/
 
if( !( isProcDir(dir_entry->d_name) ) )
{
 
//printf("running..");
 
/*
A process directory was found.
*/
 
/*
Add to path variable name of the
process directory and then add "/"
to make path correct.
*/
strcat(path, dir_entry->d_name);
strcat(path,"/");
 
//printf("%s\n", path);
 
if ( (process_directory=opendir(path) ) == NULL)
{
printf("Couldn't open process directory.");
return 1;
}
else
{
strcat(path,"stat");
 
if ( ( fp=fopen(path,"r") ) == NULL)
{
printf("Couldn't open process stat file.");
return 1;
}
else
{
fscanf(fp,"%s", &pid);
printf("PID: %s",pid);
fscanf(fp,"%s", &procName);
printf("\t\tName: %s", procName);
fscanf(fp,"%s", &state);
printf("\t\tState: %s\n", state);
 
fclose(fp);
}
 
}
 
closedir(process_directory);
 
strcpy(path,"");
strcat(path,"/proc/");
 
}
 
}
 
closedir(directory);
 
}
 
 

Thank you,
John

[Keith Thompson]

ul****@autograf.pl writes:

Hi i have got quite strange problem. I wrote programme which shows all
runnign processes. This info is get from /proc dir. When a dir that is
process dir is found stat file is read and pid, name and state are get
from it. The thing is that on my machine every time I run it, it gives
different results. Sometimes it shows nothing - most of the times.
Sometimes it shows info about 4 processes. Sometimes it works
correctly. I don't now whats wrong, I 've tried to find the mistake,
but I could'n. I begginer programmer and I don't know how to cope with
this problem. Please help me!
This is Linux-specific and off-topic in comp.nlag.c. Try
comp.os.linux.programmer.

A few things did jump out at me:
int main()
{

showRunningProcesses();

return 0;

}
showRunningProcesses() returns an int; you ignore the result.
/*

Function indicates if char given in data variable is number.
If it is it returns 0. If it is not a number it returns 1.

*/
int isNum(char data)
{

switch(data)
{
case '0': return 0;
case '1': return 0;
case '2': return 0;
case '3': return 0;
case '4': return 0;
case '5': return 0;
case '6': return 0;
case '7': return 0;
case '8': return 0;
case '9': return 0;
default : return 1;
}

}
This is backwards; logically, it should return 0 for false, 1 for
true. Names starting with "is" and a lowercase letter are reserved;
"is_Num" or "is_num" would be ok. And there's already a function that
does exactly what you want: isdigit(), declared in <ctype.h>.
/*

Function indicates if char given by *path pointer
is process dir (in /proc file system). If it is it
returns 0. If it is not it returns 1.

*/
int isProcDir(char *path)
Some of the same comments as above apply here.
{
struct stat st;
int i;
int path_length;

lstat(path, &st);
path_length = strlen(path);

//printf("running.. %s\n", path);
//printf("%o", st.st_mode);
if (S_ISDIR(st.st_mode))
return 1;
else if(S_ISLNK(st.st_mode))
return 1;
else if(S_ISCHR(st.st_mode))
return 1;
else if(S_ISBLK(st.st_mode))
return 1;
else if(S_ISFIFO(st.st_mode))
return 1;
else if(S_ISSOCK(st.st_mode))
return 1;
else if(S_ISREG(st.st_mode))
return 1;
else
{
//printf("path: %s \n", path);
//fprintf(stderr, "found");
for(i=0; i<path_length; i++)
{
if (isNum(path[i]))
{
return 1;
}
}

return 0;
}

}

int showRunningProcesses()
{

int i;
DIR *directory, *process_directory;
FILE *fp;
struct dirent *dir_entry;
char *path = (char *)malloc(50);
char *name;
char pid[10], procName[15], state[5];

strcat(path,"/proc/");

if( ( directory=opendir(path) ) == NULL )
{
fprintf(stderr, "Couldn't open /proc dir.");
return 1;

}

while(dir_entry=readdir(directory))
{

/*
Check if read directory is process
directory.
*/

if( !( isProcDir(dir_entry->d_name) ) )
{

//printf("running..");

/*
A process directory was found.
*/

/*
Add to path variable name of the
process directory and then add "/"
to make path correct.
*/
strcat(path, dir_entry->d_name);
strcat(path,"/");

//printf("%s\n", path);

if ( (process_directory=opendir(path) ) == NULL)
{
printf("Couldn't open process directory.");
return 1;
}
else
{
strcat(path,"stat");

if ( ( fp=fopen(path,"r") ) == NULL)
{
printf("Couldn't open process stat file.");
return 1;
}
else
{
fscanf(fp,"%s", &pid);
printf("PID: %s",pid);
fscanf(fp,"%s", &procName);
printf("\t\tName: %s", procName);
fscanf(fp,"%s", &state);
printf("\t\tState: %s\n", state);

fclose(fp);
}

}

closedir(process_directory);

strcpy(path,"");
strcat(path,"/proc/");

}

}

closedir(directory);

}

[/code]

Thank you,
John

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Tydr Schnubbis]

I'm not a linux programmer, but I found one thing that can make things
not work.

ul****@autograf.pl wrote:

Hi i have got quite strange problem. I wrote programme which shows all
runnign processes. This info is get from /proc dir. When a dir that is
process dir is found stat file is read and pid, name and state are get
from it. The thing is that on my machine every time I run it, it gives
different results. Sometimes it shows nothing - most of the times.
Sometimes it shows info about 4 processes. Sometimes it works
correctly. I don't now whats wrong, I 've tried to find the mistake,
but I could'n. I begginer programmer and I don't know how to cope with
this problem. Please help me!

Here is the code:

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

 int isNum(char );
 int isProcDir(char * );
 int showRunningProcesses();

 int main()
 {

     showRunningProcesses();

     return 0;

 }

 /*

 Function indicates if char given in data variable is number.
 If it is it returns 0. If it is not a number it returns 1.

 */
 int isNum(char data)
 {

     switch(data)
     {
         case '0': return 0;
         case '1': return 0;
         case '2': return 0;
         case '3': return 0;
         case '4': return 0;
         case '5': return 0;
         case '6': return 0;
         case '7': return 0;
         case '8': return 0;
         case '9': return 0;
         default : return 1;
     }

 }

 /*

 Function indicates if char given by *path pointer
 is process dir (in /proc file system). If it is it
 returns 0. If it is not it returns 1.

 */

 int isProcDir(char *path)
 {
     struct stat st;
     int i;
     int path_length;

     lstat(path, &st);
     path_length = strlen(path);

     //printf("running.. %s\n", path);
     //printf("%o", st.st_mode);
     if (S_ISDIR(st.st_mode))
         return 1;
     else if(S_ISLNK(st.st_mode))
         return 1;
     else if(S_ISCHR(st.st_mode))
         return 1;
     else if(S_ISBLK(st.st_mode))
         return 1;
     else if(S_ISFIFO(st.st_mode))
         return 1;
     else if(S_ISSOCK(st.st_mode))
         return 1;
     else if(S_ISREG(st.st_mode))
         return 1;
     else
     {
         //printf("path: %s \n", path);
         //fprintf(stderr, "found");


         for(i=0; i<path_length; i++)
         {
             if (isNum(path[i]))
             {
                 return 1;
             }
         }

         return 0;
     }

 }

 int showRunningProcesses()
 {

     int i;
     DIR *directory, *process_directory;
     FILE *fp;
     struct dirent *dir_entry;
     char *path = (char *)malloc(50);

 

If this is C code, you don't need to cast the return value of malloc.

And since you never change the size of the buffer, you can just do this

instead, and then you can remove the first strcat or strcpy too:

 

char path[50] = "/proc/";

     char *name;

     char pid[10], procName[15], state[5];

     strcat(path,"/proc/");

 

strcat won't work on uninitialized strings, use strcpy instead.

     if( ( directory=opendir(path) ) == NULL )

     {

         fprintf(stderr,    "Couldn't open /proc dir.");

         return 1;

     }

     while(dir_entry=readdir(directory))

     {

         /*

         Check if read directory is process

         directory.

         */

         if( !( isProcDir(dir_entry->d_name) ) )

         {

         //printf("running..");

         /*

         A process directory was found.

         */

         /*

         Add to path variable name of the

         process directory and then add "/"

         to make path correct.

         */

         strcat(path, dir_entry->d_name);

         strcat(path,"/");

         //printf("%s\n", path);

         if ( (process_directory=opendir(path) ) == NULL)

         {

             printf("Couldn't open process directory.");

             return 1;

         }

         else

         {

             strcat(path,"stat");

             if ( ( fp=fopen(path,"r") ) == NULL)

             {

                 printf("Couldn't open process stat file.");

                 return 1;

             }

             else

             {

                 fscanf(fp,"%s", &pid);

                 printf("PID: %s",pid);

                 fscanf(fp,"%s", &procName);

                 printf("\t\tName: %s", procName);

                 fscanf(fp,"%s", &state);

                 printf("\t\tState: %s\n", state);

                 fclose(fp);

             }

         }

         closedir(process_directory);

         strcpy(path,"");

         strcat(path,"/proc/");

 

strcpy(path,"") is the same as doing path = '\0'.  Even better, just

delete that line, and just do strcpy(path,"/proc/"). You could also do

path[6] = '\0' instead.

         }

     }

     closedir(directory);

 }