Concatenating Struct Value With Char In C Post: 302974356

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Top Forums Programming Concatenating Struct Value With Char In C Post 302974356 by Azrael on Sunday 29th of May 2016 02:09:46 AM

05-29-2016

Registered User

Concatenating Struct Value With Char In C

After googling everything I could, the best I could do with this is get the following warning with -Wall:

Code:

gcc -Wall help.c -o help
help.c: In function �findpid':
help.c:29:25: warning: passing argument 2 of �strncat' from incompatible pointer type
           strncat( pro, &str, 60);
                         ^
In file included from help.c:3:0:
/usr/include/string.h:140:14: note: expected �const char * __restrict__' but argument is of type �char (*)[60]'
 extern char *strncat (char *__restrict __dest, const char *__restrict __src,
              ^

Here's what I have for my code:

Code:

#include <stdio.h>
#include <dirent.h>
#include <string.h>

void findpid(char *filename){

    char pro[60] = "/proc/";
    char fd[5] = "/fd/";
    char pid[7];
    char str[60];
    char dir[60];
    FILE *file;
    file = fopen(filename,"r");
    while(fgets(pid, sizeof(pid), file)!=NULL)
    strtok(pid, "\n"); // Strip newline.
    strncat( pro, pid, 10 );
    strncat( pro, fd, 10 );
    strncat( dir, pro, 10);
    fclose(file);

    DIR *dp;
    struct dirent *ep;

    dp = opendir (pro);
    if (dp != NULL)
      {
        while ((ep = readdir (dp)) != NULL)
          memcpy(str, ep->d_name, 60);
          strncat( pro, &str, 60);
          printf("%s\n", pro);
        (void) closedir (dp);
      }
    else
      perror ("Couldn't open the directory");

}

int main(void)
{
    if (fopen("/var/run/apache2/apache2.pid", "r") != NULL) {
        char filename[] = "/var/run/apache2/apache2.pid";
        findpid(filename);
    }

    else if (fopen("/var/run/httpd/httpd.pid", "r") != NULL) {
        char filename[] = "/var/run/httpd/httpd.pid";
        findpid(filename);
    }
    else if (fopen("/var/run/nginx.pid", "r") != NULL) {
        char filename[] = "/var/run/nginx.pid";
        findpid(filename);
    }
    else {
        printf("Nothing found.\n");
    }

    return (0);
}

If Apache or Nginx are running it should grab the pid from /var/run and list its directory in /proc/$pid/fd. Right now, replacing the code in the while loop with "printf("%s%s\n", pro, ep->d_name);" works just fine. However, my current code dies after listing one directory at that location.

I tried casting, dereferncing pointers and a lot of other things I could think of, but kept getting segmentation faults. Any suggestions greatly appreciated.

Azrael

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LEARN ABOUT DEBIAN

paps

PAPS(1) 						      General Commands Manual							   PAPS(1)

NAME

       paps - UTF-8 to PostScript converter using Pango

SYNOPSIS

       paps [options] files...

DESCRIPTION

       paps reads a UTF-8 encoded file and generates a PostScript language rendering of the file. The rendering is done by creating outline curves
       through the pango ft2 backend.

OPTIONS

       These programs follow the usual GNU command line syntax, with long options starting with  two  dashes  (`-').   A  summary  of  options	is
       included below.

       --landscape
	      Landscape output. Default is portrait.

       --columns=cl
	      Number of columns output. Default is 1.
	      Please notice this option isn't related to the terminal length as in a "80 culums terminal".

       --font=desc
	      Set the font description. Default is Monospace 12.

       --rtl  Do right to left (RTL) layout.

       --paper ps
	      Choose paper size. Known paper sizes are legal, letter and A4. Default is A4.

       Postscript points
	      Each postscript point equals to 1/72 of an inch. 36 points are 1/2 of an inch.

       --bottom-margin=bm
	      Set bottom margin. Default is 36 postscript points.

       --top-margin=tm
	      Set top margin. Default is 36 postscript points.

       --left-margin=lm
	      Set left margin. Default is 36 postscript points.

       --right-margin=rm
	      Set right margin. Default is 36 postscript points.

       --gutter-width=gw
	      Set gutter width. Default is 40 postscript points.

       --help Show summary of options.

       --header
	      Draw page header for each page.

       --markup
	      Interpret the text as pango markup.

       --lpi  Set the lines per inch. This determines the line spacing.

       --cpi  Set the characters per inch. This is an alternative method of specifying the font size.

       --stretch-chars
	      Indicates  that  characters  should be stretched in the y-direction to fill up their vertical space. This is similar to the texttops
	      behaviour.

AUTHOR

       paps was written by Dov Grobgeld <dov.grobgeld@gmail.com>.

       This manual page was written by Lior Kaplan <kaplan@debian.org>, for the Debian project (but may be used by others).

								  April  17, 2006							   PAPS(1)

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