How to read in file size

[Christopher North-Keys]

> I am using BSD Unix 4.2 on Sun 3's, a Sparc, and on a Encore multimax. I
> do not think this is a machine dependent question, but this info is for
> anyone who might flame me later for not specifing it.
>
> I am aware of the wc (word count) program in unix.  I can use something
> like this in my C program.....
>       system ("wc -c filename") ;

No! (blech!)

See the library function "fstat".  A code fragment from SunOS follows.
The reference to the file size is the line:

    if((*addr_buffer=(char *)calloc(1, statbuf.st_size+1))==NULL)
                                       ^^^^^^^^^^^^^^^

#-------------------------------------------------------------------------

/* I haven't check this include-list for non-essentials */
#include <stdio.h>
#include <sys/file.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <ctype.h>
#include "stdelf.h"

long
SwallowFile(addr_buffer, path)      /* North-Keys, 1989 */
char **addr_buffer, *path;
{
    struct stat statbuf;
    int         in_count;
    int         fd = -1;

    /* Attempt to open desired file */
    if(((fd)=open(path, O_RDONLY))==-1)
    {
        (void)fprintf(stderr, "SwallowFile: %s not opened\n", path);
        return (FAIL);
    }

    if(fstat(fd, &statbuf)==-1)
    {
        (void)fprintf(stderr, "SwallowFile: error on fstat file %s\n", path);
        return (FAIL);
    }

    /* Get a buffer to fit */
    if((*addr_buffer=(char *)calloc(1, statbuf.st_size+1))==NULL)
    {
        (void)fprintf(stderr, "SwallowFile: no space for calloc\n");
        return (FAIL);
    }

    /* Read in the file */
    if((in_count = read(fd, *addr_buffer, statbuf.st_size)) != statbuf.st_size)
    {
        (void)fprintf(stdout,
                      "SwallowFile: error(?) %d/%d bytes read from %s\n",
                      in_count, statbuf.st_size, path);
        (void)free(*addr_buffer);
        return (FAIL);
    }
    return (in_count);
}


-- 
--Christopher Alexander North-Keys----/\--------------------------------------
  Co-founder Group Talisman          /  \/\ ^*^               Harp[@Mcc.Com]
  [*my* opinions]                   /    \ \       Associate Systems Analyst
--------------------------Microelectronics & Computer Technology Corporation--