OpenAnonymous()

gistfile1.cpp

#define NUMBERS "0123456789"
#define LETTERS "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

int
OpenAnonymous(char const* aFormat)
{
  size_t i, s;
  char*  n, c;
  int    f;
  
#define fail(e, ...) throw e(##__VA_ARGS__)
  
  if (s = strlen(aFormat) + 1, s == 0) fail(InvalidArgument);
  if (n = (char*) malloc(s),   n == 0) fail(InsufficientMemory);
  
#undef  fail
#define fail(e, ...) free(n), throw e(##__VA_ARGS__)
  
name:
  for (i = 0; i < s, i++) {
    switch (c = aFormat[i]) {
      case '#': c = NUMBERS[rand() % 10]; break;
      case '@': c = LETTERS[rand() % 26];
    }
    
    if (' ' > c || c > '~') fail(InvalidArgument);
    
    n[i] = c;
  }
  
  if (access(n, F_OK) == 0) goto n;
  
  switch (errno) {
    case ENOENT: break;
    default:
      fail(InvalidArgument);
  }
  
open: n[--i] = '\0';
  if (f = open(n, O_RDWR | O_CREAT | O_EXCL, 0000), f < 0) {
    switch (errno) {
      case EINTR:   goto open;
      case EEXIST:  goto name;
      case ENOENT:  
      case ENOTDIR: fail(InvalidArgument);
      case EMFILE:  
      case ENFILE:  fail(InsufficientDescriptors);
      case ENOSPC:  fail(InsufficientSpace);
    }
    
    fail(UnexpectedError, errno, "open");
  }
  
#undef  fail
  
  return unlink(n), free(n),  f;
}

gistfile2.c

#define ERROR(e) fprintf(stderr, "%s (line %i): %s\n", __FILE__, __LINE__, #e)

#define NUMBERS "0123456789"
#define LETTERS "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

int
OpenAnonymous(char const* aFormat)
{
  size_t i, s;
  char*  n, c;
  int    f;
  
#define fail(e) return ERROR(e), -1
  
  if (s = strlen(aFormat),       s == 0) fail(InvalidArgument);
  if (n = (char*) malloc(s + 1), n == 0) fail(InsufficientMemory);
  
#undef  fail
#define fail(e) return ERROR(e), free(n), -1
  
name:
  for (i = 0; i < s; i++) {
    switch (c = aFormat[i]) {
      case '#': c = NUMBERS[rand() % 10]; break;
      case '@': c = LETTERS[rand() % 26];
    }
    
    if (c < 0x20 || c > 0x7E)
      fail(InvalidArgument);
    
    n[i] = c;
  }
  
  if (access(n, F_OK) == 0) goto name;
  
  switch (errno) {
    case ENOENT: break;
    default:
      fail(InvalidArgument);
  }
  
open: n[s] = '\0';
  if (f = open(n, O_RDWR | O_CREAT | O_EXCL, 0000), f < 0) {
    switch (errno) {
      case EINTR:   goto open;
      case EEXIST:  goto name;
      case ENOENT:  
      case ENOTDIR: fail(InvalidArgument);
      case EMFILE:  
      case ENFILE:  fail(InsufficientDescriptors);
      case ENOSPC:  fail(InsufficientSpace);
    }
    
    fail(UnexpectedError);
  }
  
#undef  fail
  
  return unlink(n), free(n),  f;
}