Thread: adding data to the middle of a file from another file

I want to write a program that will look for a specified line in an .asm source file, and place my procedure calls from another file into it. I want it to work sort of like the #include preprocessor directive, but for assembly source. Here's the code I've been using:

Code:

#include <stdio.h>

int find(FILE *fp, char *find)
{
 while ((fscanf(fp, "%c", *find) != 1)
 {
  if (ferror(fp))
  {
   fclose(fp);
   return -1;
  }
  if (feof(fp))
  {
   fclose(fp));
   return -2;
  }
  fscanf(fp, "%*[^\n]");
 }
}
void filecopy(FILE *ipf, FILE *opf)
{
 char c;
 
 while ((c = getc(ipf)) != EOF)
 {
  putc(c, opf);
 }
}
main (int argc, char *argv[])
{
 FILE *fp, *fp2;
 long int found, file_pos, file2_pos;

 if (argc != 3)
 {
  printf("Usage: link filename filename2\n");
  return 2;
 }
 if ((fp = fopen(argv[1], "a+")) == NULL)
 {
  printf("Error: %s cannot be opened.", argv[1]);
  return 1;
 }
 if ((fp2 = fopen(argv[2], "a+")) == NULL)
 {
  printf("Error: %s cannot be opened.", argv[2]);
  return 1;
 }
 found = find(fp, '&');
 if (found == -1)
 {
  printf("File error!");
  return 0;
 }
 if (found == -2)
 {
  printf("No call was made for include macro!");
  return 0;
 }
 fgetpos(fp, &file_pos);
 fgetpos(fp2, &file2_pos
 fseek(fp, 7L, SEEK_CUR);
 fseek(fp2, 0L, SEEK_END);
 fprintf(fp2, "\n");
 filecopy(fp, fp2);
 fsetpos(fp, &file_pos);
 fseek(fp2, 0L, SEEK_SET);
 filecopy(fp2, fp);
 fclose(fp);
 fclose(fp2);
 return 0;
}

If anyone could be so kind as to tell me what i'm doing wrong, I would be extremely pleased! Also, it compiles fine, but it never performs the file routines that i wrote into it.

http://c-faq.com/stdio/insdelrec.html

[edit]And there's a fair amount of other bad in the code you posted -- syntax errors and things mentioned in the FAQ (such as EOF and the return value of [f]getc).

Originally Posted by xixpsychoxix

that site was no help at all. There must be some way to do it, because otherwise the preprocessor couldn't add lines from <stdio.h> or any other file.

I'll be more direct: "The usual solution is simply to rewrite the file." Is this not a simple option?

Either create a new file and write to it from the old file until the point where you want to insert something, then write the insertion, then write the rest of the old file, OR save the contents of the old file past the insertion point, then write over the file from that point, first with the insertion, then with the stored remains of the old file.

Something simple and kinda cat-like might be like this.

Code:

#include <stdio.h>
#include "foo.h"
#include "bar.h"

int main (void)
{
   static const char sname[] = __FILE__;
   FILE *source = fopen(sname, "r");
   if ( source != NULL )
   {
      char hname[256], line[32];
      while ( fgets(line, sizeof line, source) != NULL )
      {
         if ( sscanf(line, "#include \"%255[^\"]\"", hname) == 1 )
         {
            FILE *header = fopen(hname, "r");
            if ( header != NULL )
            {
               while ( fgets(line, sizeof line, header) != NULL )
               {
                  fputs(line, stdout);
               }
            }
            else
            {
               perror(hname);
            }
         }
         else
         {
            fputs(line, stdout);
         }
      }
   }
   else
   {
      perror(sname);
   }
   return 0;
}

I'd leave you to change the streams to suit your needs.

> because otherwise the preprocessor couldn't add lines from <stdio.h> or any other file.
The pre-processor never modifies the original file, it just prints it (with substitutions)

How about includes within includes?

Code:

#include <stdio.h>

void copy ( FILE *out, const char *filename ) {
  char buff[BUFSIZ];
  FILE *in = fopen( filename, "r" );
  if ( in ) {
    while ( fgets( buff, sizeof buff, in ) ) {
      char hname[BUFSIZ];
      if ( sscanf(line, "#include \"%255[^\"]\"", hname) == 1 ) {
        copy( out, hname );
      } else {
        fputs( out, buff );
      }
    }
    fclose( in );
  }
}

int main ( ) {
  copy( stdout, "myfile.asm" );
  return getchar();
}

You mean you want someone to say yet again, you can't just fseek to the middle of a file and expect to be able to insert data.

You can overwrite it, but there is no insert.

There, I've said it again - happy now?