libc: Implement ferror() and feof()

apps/src/init.c

@@ -36,19 +36,13 @@ int main()
     if (!config)
     {
         perror("fopen");
-        // return 1;
+        return 1;
     }
 
     char buf[4096];
 
     size_t nread = fread(buf, sizeof(buf), 1, config);
-    if (nread == 0 && errno != 0) // FIXME: looks like our only way of checking whether a zero-read is an error or eof
-                                  // right now is checking errno, since fread() does not differentiate between the two,
-                                  // and feof() and ferror() are not yet implemented
-    {
-        perror("fread");
-        // return 1;
-    }
+    if (ferror(config)) { perror("fread"); }
     else
     {
         buf[nread] = 0;
@@ -58,11 +52,7 @@ int main()
         printf("%s", buf);
     }
 
-    if (fclose(config) < 0)
-    {
-        perror("fclose");
-        // return 1;
-    }
+    if (fclose(config) < 0) { perror("fclose"); }
 
     printf("\n\nPress any key to restart.\n");
 

libs/libc/include/stdio.h

@@ -8,7 +8,9 @@
 
 typedef struct
 {
-    int fd;
+    int f_fd;
+    int f_eof;
+    int f_err;
 } FILE;
 
 #ifdef __cplusplus
@@ -26,6 +28,9 @@ extern "C"
     int fseek(FILE*, long, int);
     long ftell(FILE*);
     size_t fwrite(const void*, size_t, size_t, FILE*);
+    int ferror(FILE*);
+    int feof(FILE*);
+    void clearerr(FILE*);
     void setbuf(FILE*, char*);
     int vfprintf(FILE*, const char*, va_list);
     int printf(const char*, ...);

libs/libc/src/file.cpp

@@ -9,7 +9,7 @@ extern "C"
 {
     int fclose(FILE* stream)
     {
-        int status = close(stream->fd);
+        int status = close(stream->f_fd);
         if (status < 0)
         {
             int savederr = errno;
@@ -32,20 +32,38 @@ extern "C"
         int fd = open(pathname, O_RDONLY); // FIXME: Use the mode string.
         if (fd < 0) { return 0; }
         FILE* stream = (FILE*)malloc(sizeof(FILE));
-        stream->fd = fd;
+        stream->f_fd = fd;
+        clearerr(stream);
         return stream;
     }
 
     size_t fread(void* buf, size_t size, size_t nmemb, FILE* stream)
     {
-        ssize_t status = read(stream->fd, buf, size * nmemb);
+        ssize_t status = read(stream->f_fd, buf, size * nmemb);
         if (status < 0)
-            return 0; // FIXME: The manual says that fread() does not differentiate between EOF and error, and that
-                      // ferror() and feof() should be called to determine such. So right now, we just mask the error,
-                      // until that is implemented.
+        {
+            stream->f_err = 1;
+            return 0;
+        }
+        if (status == 0) stream->f_eof = 1;
         return (size_t)status;
     }
 
+    int ferror(FILE* stream)
+    {
+        return stream->f_err;
+    }
+
+    int feof(FILE* stream)
+    {
+        return stream->f_eof;
+    }
+
+    void clearerr(FILE* stream)
+    {
+        stream->f_err = stream->f_eof = 0;
+    }
+
     int fseek(FILE*, long, int)
     {
         NOT_IMPLEMENTED("fseek");