glibc/stdio-common/xbug.c

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


typedef struct _Buffer {
  char *buff;
  int  room, used;
} Buffer;

void InitBuffer (Buffer *b);
void AppendToBuffer (Buffer *b, const char *str, int len);
void ReadFile (Buffer *buffer, FILE *input);

#define INIT_BUFFER_SIZE 10000

void
InitBuffer (Buffer *b)
{
  b->room = INIT_BUFFER_SIZE;
  b->used = 0;
  b->buff = (char *)malloc(INIT_BUFFER_SIZE*sizeof(char));
}

void
AppendToBuffer (Buffer *b, const char *str, int len)
{
  while (b->used + len > b->room) {
    b->buff = (char *)realloc(b->buff, 2*b->room*(sizeof(char)));
    b->room *= 2;
  }
  strncpy(b->buff + b->used, str, len);
  b->used += len;
}

void
ReadFile (Buffer *buffer, FILE *input)
{
  char       buf[BUFSIZ + 1];
  int        bytes;

  buffer->used = 0;
  while (!feof(input) && (bytes = fread(buf, 1, BUFSIZ, input)) > 0) {
    AppendToBuffer(buffer, buf, bytes);
  }
  AppendToBuffer(buffer, "", 1);
}

int
main(int argc, char *argv[])
{
  char filename[] = "xbug.c";
  FILE *input;
  Buffer buffer;

  InitBuffer(&buffer);

  if (!freopen (filename, "r", stdin))
    fprintf(stderr, "cannot open file\n");

  unsetenv ("LD_LIBRARY_PATH");

  if (!(input = popen("/bin/cat", "r")))
    fprintf(stderr, "cannot run \n");

  ReadFile(&buffer, input);
  pclose(input);

  return 0;
}