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

typedef struct
{
   int width;     /* Maximum line length, excluding terminating LF */
   int height;    /* Line count */
   int size;      /* File size */
   int capacity;  /* Buffer size */
   char *data;    /* File contents */
   char *cursor;  /* Current read position */
} FileInfo;

/* Load file to memory, returns 0 on success */
static int LoadFile(FILE *infile, FileInfo *data)
{
   int read_size;

   do
   {
      data->capacity += 0x10000;
      if( (data->data = realloc(data->data, data->capacity + 1)) == NULL )
         return !puts("Out of memory");
      read_size = fread(data->data + data->size, 1, 0x10000, infile);
      data->size += read_size;
   } while( read_size == 0x10000 );

   /* Always make sure file ends with a LF */
   data->data[data->size] = '\n';
   data->cursor = data->data;
   return 0;
}

/* Get file dimensions */
static void GetFileDimensions(FileInfo *file)
{
   int width;
   int i, j;

   for(i = 0; i < file->size; i = j + 1)
   {
      for(j = i; j < file->size && file->data[j] != '\n'; j++);
      width = j - i;
      if( width > file->width )
         file->width = width;
      file->height++;
   }
}

/* Output concatenated files */
static void Concat(int argc, FileInfo *files)
{
   int max_line_count = 0;
   int i, j, width;

   for(i = 1; i < argc; i++)
   {
      if( files[i].height > max_line_count )
         max_line_count = files[i].height;
   }
   for(i = 0; i < max_line_count; i++)
   {
      for(j = 1; j < argc; j++)
      {
         width = 0;
         if( files[j].cursor - files[j].data < files[j].size )
         {
            while( *(files[j].cursor) != '\n' )
            {
               putchar(*(files[j].cursor));
               width++;
               files[j].cursor++;
            }
            files[j].cursor++;
         }
         for(; width < files[j].width; width++)
            putchar(' ');
      }
      putchar('\n');
   }
}

int main(int argc, char **argv)
{
   int i, j;
   FileInfo *files;
   FILE *infile;

   /* Load files */
   if( (files = (FileInfo*)calloc(sizeof(FileInfo), argc)) == NULL )
      return !puts("Out of memory");
   for(i = 1; i < argc; i++)
   {
      for(j = 1; j < i; j++)
      {
         if( strcmp(argv[i], argv[j]) == 0 )
         {
            /* Duplicate file specified on command line, no need to
               load the same file again.                            */
            memcpy(&files[i], &files[j], sizeof(FileInfo));
            break;
         }
      }
      if( j < i )
         continue;
      if( strcmp(argv[i], "-") == 0 )
      {
         /* Load stdin */
         if( LoadFile(stdin, &files[i]) != 0 )
            return 1;
      }
      else
      {
         if( (infile = fopen(argv[i], "rb")) == NULL )
            return printf("Can not open %s\n", argv[i]);
         j = LoadFile(infile, &files[i]);
         fclose(infile);
         if( j != 0 )
            return 1;
      }
      GetFileDimensions(&files[i]);
   }

   /* Output concatenated files */
   Concat(argc, files);

   /* Don't bother freeing memory */
   return 0;
}