A ls -l of sorts

Another common Unix command line tool is ls. The program ls lists the contents of a given directory. In addition the program ls can be used to examine various file properties. For example the following command line call to the program ls used with the -l option

% ls -l GATErrors.h

will print out the following information about the file GATErrors.h

-rw-r--r--  1 leonardo  masters  14477 15 Apr 11:13 GATErrors.h

The first bit of this printout -rw-r--r-- indicates who can read and write the file GATErrors.h; the portion 14477 indicates the length of the file GATErrors.h in bytes, and the portion 15 Apr 11:13 indicates the last write time of the file GATErrors.h. As has become our habit, we will create a ``grid enabled'' version of ls -l. The full program is as follows

#include <stdio.h>
#include "GAT.h"

int main( int argc, char *argv[] )
{
  char writeChar;
  char readChar;
  GATResult result;
  GATFile sourceFile;
  GATContext context;
  unsigned long length;
  GATTime lastWriteTime;
  GATLocation sourceLocation;
  
  /* Check command line syntax */
  if( 2 != argc )
  {
     printf("usage: %s file\n", argv[0]);
     
     return 1;
  }
  
  /* Set result to a memory failure */
  result = GAT_MEMORYFAILURE;
  
  /* Create GATLocation sourceLocation */
  sourceLocation = GATLocation_Create( argv[1] );
  
  /* Check previous GATLocation creation */
  if( NULL != sourceLocation )
  {
      /* Create GATContext context */
      context = GATContext_Create();
      
      /* Check previous GATContext creation */
      if( NULL != context )
      {
        /* Create GATFile sourceFile */
        sourceFile = GATFile_Create( context, sourceLocation, NULL );
        
        /* Check GATFile creation */
        if( NULL != sourceFile )
        {
          /* Obtain  GATFile length */
          result = GATFile_GetLength( sourceFile,  &length );
          
          /* Check call to GATFile_GetLength
          if( GAT_SUCCEEDED( result ) )
          {
            /* Obtain GATFile lastWriteTime */
            result = GATFile_LastWriteTime( sourceFile, &lastWriteTime );
            
            /* Check call to GATFile_LastWriteTime */
            if( GAT_SUCCEEDED( result ) )
            { 
              /* Determine readability */
              result = GATFile_IsReadable( sourceFile );
              
              /* Check call to GATFile_IsReadable */
              if( GAT_SUCCEEDED( result ) )
              {
                /* Set readChar */
                readChar = '-';
                if( GAT_SUCCESS == result )
                {
                  readChar = 'r';
                }
                
                /* Determine writability */
                result = GATFile_IsWritable( sourceFile );
                
                /* Check call to GATFile_IsWritable */
                if( GAT_SUCCEEDED( result ) )
                {
                  /* Set writeChar */
                  writeChar = '-';
                  if( GAT_SUCCESS == result )
                  {
                    writeChar = 'w';
                  }
                  
                  /* Print results in the form: rw length lastWriteTime file */
                  printf( "%c%c %d %d %s\n", 
                           readChar, writeChar, length, 
                           GATTime_GetTime(lastWriteTime), argv[1] );
                }
              }
              
              /* Destroy GATTime */
              GATTime_Destroy( &lastWriteTime );
            }
          }
          
          /* Destroy GATFile sourceFile */
          GATFile_Destroy( &sourceFile );
        }
        
        /* Destroy GATContext context */
        GATContext_Destroy( &context );
      }
      
    /* Destroy GATLocation sourceLocation */
    GATLocation_Destroy( &sourceLocation );
  }
  
  /* Check result for success and print error */
  if( GAT_FAILED( result) )
  {
    printf( "An error has occurred during the delete operation\n");
    
    return 1;
  }
  
  return 0;
}

Again this entire program contains no novel code; so, we will not examine it line by line.