Use -1 instead of EOF for an invalid file descriptor

The POSIX standards specify that the open() and openat() functions
technically return -1, not EOF, on failure -- even though most (perhaps
all) systems define EOF to be -1!

src/fileio.c

@@ -466,7 +466,7 @@ bool save_game (int num)
     // Create the data directory, if needed
     data_dir = data_directory();
     data_dir_fd = data_directory_fileno();
-    if (data_dir != NULL && data_dir_fd == EOF) {
+    if (data_dir != NULL && data_dir_fd == -1) {
 	if (xmkdir(data_dir, S_IRWXU | S_IRWXG | S_IRWXO) != 0) {
 	    // Data directory could not be created
 	    saved_errno = errno;

src/utils.c

@@ -231,7 +231,7 @@ static const unsigned char xor_table[] = {
 
 static char *home_directory_str = NULL;		// Full pathname to home
 static char *data_directory_str = NULL;		// Writable data dir pathname
-static int data_directory_fd    = EOF;		// Data dir file descriptor
+static int data_directory_fd    = -1;		// Data dir file descriptor
 
 static bool is_posix_locale = false;		// Override strfmon()?
 
@@ -418,7 +418,7 @@ const char *data_directory (void)
 		strcat(p, program_name);
 
 		data_directory_fd = open(p, O_DIRECTORY | O_SEARCH);
-		if (data_directory_fd != EOF) {
+		if (data_directory_fd != -1) {
 		    // Directory "$HOME/.trader" exists: use that
 		    data_directory_str = p;
 		} else {
@@ -460,7 +460,7 @@ const char *data_directory (void)
 	}
     }
 
-    if (data_directory_str != NULL && data_directory_fd == EOF) {
+    if (data_directory_str != NULL && data_directory_fd == -1) {
 	data_directory_fd = open(data_directory_str, O_DIRECTORY | O_SEARCH);
     }
 
@@ -473,7 +473,7 @@ const char *data_directory (void)
 
 int data_directory_fileno (void)
 {
-    if (data_directory_fd == EOF) {
+    if (data_directory_fd == -1) {
 	(void) data_directory();
     }
 
@@ -553,7 +553,7 @@ FILE *game_fopen (int gamenum, const char *mode)
     }
 
     ddfd = data_directory_fileno();
-    if (ddfd == EOF) {
+    if (ddfd == -1) {
 	ddfd = AT_FDCWD;
     }
 
@@ -572,7 +572,7 @@ FILE *game_fopen (int gamenum, const char *mode)
     fd = openat(ddfd, gfn, oflag, omode);
     free(gfn);
 
-    return (fd == EOF) ? NULL : fdopen(fd, mode);
+    return (fd == -1) ? NULL : fdopen(fd, mode);
 }
 
 

src/utils.h

@@ -108,12 +108,12 @@ extern const char *data_directory (void);
 /*
   Function:   data_directory_fileno - Return file descriptor of data directory
   Parameters: (none)
-  Returns:    int                   - File descriptor, or EOF on failure
+  Returns:    int                   - File descriptor, or -1 on failure
 
   This function returns the file descriptor of the potentially-writable
-  data directory returned by data_directory(), or EOF (-1) if that
-  directory does not exist.  Note that this function does NOT create the
-  data directory itself.
+  data directory returned by data_directory(), or -1 if that directory
+  does not exist.  Note that this function does NOT create the data
+  directory itself.
 */
 extern int data_directory_fileno (void);
 
@@ -142,11 +142,11 @@ extern char *game_filename (int gamenum);
   Returns:    FILE *     - Pointer to open file structure
 
   This function opens a game file for reading or writing, depending on
-  the contents of mode, returning a pointer to the open file structure.
-  Note that the data directory must be created before calling this
-  function, by checking whether data_directory_fileno() returns EOF: if
-  so, the directory must be created.  NULL is returned (and errno set) if
-  the file cannot be opened successfully.
+  the mode string, returning a pointer to the open file structure.  Note
+  that the data directory must be created before calling this function,
+  by checking whether data_directory_fileno() returns -1: if so, the
+  directory must be created.  NULL is returned (and errno set) if the
+  file cannot be opened successfully.
 */
 extern FILE *game_fopen (int gamenum, const char *mode);