Fixed <stdio.h> file and dereferencing bugs

src/libc/clearerr.c

@@ -1,5 +1,7 @@
 #include "__fileioc_stdio.h"
 
+#include <stdint.h>
+
 void __attribute__((weak)) clearerr(FILE *stream)
 {
     if (stream == NULL ||
@@ -9,7 +11,7 @@ void __attribute__((weak)) clearerr(FILE *stream)
     {
         return;
     }
-
-    _file_streams[stream->slot].eof = 0;
-    _file_streams[stream->slot].err = 0;
+    uint8_t index = stream->slot - 1;
+    _file_streams[index].eof = 0;
+    _file_streams[index].err = 0;
 }

src/libc/fclose.c

@@ -1,5 +1,7 @@
 #include "__fileioc_stdio.h"
 
+#include <stdint.h>
+
 int __attribute__((weak)) fclose(FILE *stream)
 {
     ti_var_t slot;
@@ -14,8 +16,13 @@ int __attribute__((weak)) fclose(FILE *stream)
 
     slot = stream->slot;
 
-    _file_streams[slot - 1].slot = 0;
-
     int status = ti_Close(slot);
-    return (status == 0) ? EOF : 0;
+    if (status == 0)
+    {
+        // failed to close file
+        return EOF;
+    }
+    uint8_t index = slot - 1;
+    _file_streams[index].slot = 0;
+    return 0;
 }

src/libc/feof.c

@@ -2,5 +2,9 @@
 
 int __attribute__((weak)) feof(FILE *stream)
 {
+    if (stream == NULL || stream == stdin || stream == stdout || stream == stderr)
+    {
+        return 0;
+    }
     return stream->eof;
 }

src/libc/ferror.c

@@ -2,5 +2,9 @@
 
 int __attribute__((weak)) ferror(FILE *stream)
 {
+    if (stream == NULL || stream == stdin || stream == stdout || stream == stderr)
+    {
+        return 0;
+    }
     return stream->err;
 }

src/libc/fgetc.c

@@ -2,26 +2,17 @@
 
 int __attribute__((weak)) fgetc(FILE *stream)
 {
-    int c;
-
-    if (stream == NULL)
+    if (stream == NULL || stream == stdout || stream == stderr)
     {
         return EOF;
     }
-
-    if (stream == stdout || stream == stderr)
-    {
-        c = EOF;
-    }
-    else if (stream == stdin)
+    if (stream == stdin)
     {
-        c = getchar();
-    }
-    else
-    {
-        c = ti_GetC(stream->slot);
+        return getchar();
     }
 
+    int c = ti_GetC(stream->slot);
+
     if (c == EOF)
     {
         stream->eof = 1;

src/libc/fopen.c

@@ -5,15 +5,14 @@
 FILE* __attribute__((weak)) fopen(const char *__restrict filename, const char *__restrict mode)
 {
     ti_var_t slot;
-    uint8_t index;
 
     slot = ti_Open(filename, mode);
     if (slot == 0)
     {
         return NULL;
     }
 
-    index = slot - 1;
+    uint8_t index = slot - 1;
     _file_streams[index].slot = slot;
     _file_streams[index].eof = 0;
     _file_streams[index].err = 0;

src/libc/fputc.c

@@ -2,32 +2,21 @@
 
 int __attribute__((weak)) fputc(int c, FILE *stream)
 {
-    int ret;
-
-    if (stream == NULL)
+    if (stream == NULL || stream == stdin)
     {
         return EOF;
     }
-
-    if (stream == stdin)
+    if (stream == stdout || stream == stderr)
     {
-        ret = EOF;
-    }
-    else if (stream == stdout || stream == stderr)
-    {
-        ret = putchar(c);
-    }
-    else
-    {
-        ret = ti_PutC((char)c, stream->slot);
+        return putchar(c);
     }
 
+    int ret = ti_PutC((char)c, stream->slot);
+    /*
+     * `ti_PutC` returns `(unsigned char)c` or `EOF` so we can skip testing for
+     * the case of `ret != (unsigned char)c`
+     */
     if (ret == EOF)
-    {
-        stream->eof = 1;
-    }
-
-    if (ret != c)
     {
         stream->err = 1;
     }

src/libc/fread.c

@@ -2,11 +2,12 @@
 
 size_t __attribute__((weak)) fread(void *ptr, size_t size, size_t count, FILE *__restrict stream)
 {
-    size_t ncount;
-
-    if (stream == NULL ||
-        stream == stdout ||
-        stream == stderr)
+    if (stream == NULL || stream == stdout || stream == stderr)
+    {
+        return 0;
+    }
+    // If size or count is zero, fread returns zero and performs no other action.
+    if (size == 0 || count == 0)
     {
         return 0;
     }
@@ -16,6 +17,7 @@ size_t __attribute__((weak)) fread(void *ptr, size_t size, size_t count, FILE *_
         int c;
         char *p = ptr;
         size_t len = size * count;
+        size_t bytes_read = 0;
 
         for (; len > 0; len--)
         {
@@ -24,12 +26,13 @@ size_t __attribute__((weak)) fread(void *ptr, size_t size, size_t count, FILE *_
                 break;
             }
             *p++ = (char)c;
+            bytes_read++;
         }
 
-        return count;
+        return bytes_read / size;
     }
 
-    ncount = ti_Read(ptr, size, count, stream->slot);
+    size_t ncount = ti_Read(ptr, size, count, stream->slot);
     if (ncount != count)
     {
         stream->err = 1;

src/libc/fseek.c

@@ -1,6 +1,6 @@
 #include "__fileioc_stdio.h"
 
-int __attribute__((weak)) fseek(FILE *stream, long int offset, int origin)
+int __attribute__((weak)) fseek(FILE *stream, long offset, int origin)
 {
     if (stream == NULL ||
         stream == stdin ||
@@ -9,6 +9,5 @@ int __attribute__((weak)) fseek(FILE *stream, long int offset, int origin)
     {
         return -1;
     }
-
-    return ti_Seek((int)offset, origin, stream->slot);
+    return (ti_Seek((int)offset, origin, stream->slot) == EOF) ? -1 : 0;
 }

src/libc/ftell.c

@@ -1,7 +1,7 @@
 #include "__fileioc_stdio.h"
 #include <stdint.h>
 
-long int __attribute__((weak)) ftell(FILE *stream)
+long __attribute__((weak)) ftell(FILE *stream)
 {
     if (stream == NULL ||
         stream == stdin ||
@@ -14,5 +14,5 @@ long int __attribute__((weak)) ftell(FILE *stream)
     // ti_Tell shouldn't return a value greater than OS_VAR_MAX_SIZE (65512) unless an error occurs
     uint16_t ret = ti_Tell(stream->slot);
     // Convert a result of UINT16_MAX to -1L, leaving other results the same
-    return ((uint16_t)ret + 1) - 1L;
+    return (uint16_t)(ret + 1) - 1L;
 }

src/libc/fwrite.c

@@ -2,34 +2,35 @@
 
 size_t __attribute__((weak)) fwrite(const void *__restrict ptr, size_t size, size_t count, FILE *__restrict stream)
 {
-    size_t ncount;
-
-    if (stream == NULL ||
-        stream == stdin)
+    if (stream == NULL || stream == stdin)
+    {
+        return 0;
+    }
+    // If size or count is zero, fwrite returns zero and performs no other action.
+    if (size == 0 || count == 0)
     {
         return 0;
     }
 
-    if (stream == stdout ||
-        stream == stderr)
+    if (stream == stdout || stream == stderr)
     {
         char *p = (char *)ptr;
         size_t len = size * count;
-        size_t num = 0;
+        size_t bytes_written = 0;
 
         for (; len > 0; len--)
         {
             if (putchar(*p++) == EOF)
             {
                 break;
             }
-            num++;
+            bytes_written++;
         }
 
-        return num / size;
+        return bytes_written / size;
     }
 
-    ncount = ti_Write(ptr, size, count, stream->slot);
+    size_t ncount = ti_Write(ptr, size, count, stream->slot);
     if (ncount != count)
     {
         stream->err = 1;

src/libc/include/stdio.h

@@ -61,9 +61,9 @@ size_t fread(void *__restrict ptr, size_t size, size_t count, FILE *__restrict s
 
 size_t fwrite(const void *__restrict ptr, size_t size, size_t count, FILE *__restrict stream);
 
-long int ftell(FILE *stream) __attribute__((__warn_unused_result__));
+long ftell(FILE *stream) __attribute__((__warn_unused_result__));
 
-int fseek(FILE *stream, long int offset, int origin);
+int fseek(FILE *stream, long offset, int origin);
 
 void rewind(FILE *stream);
 

src/libc/rewind.c

@@ -2,6 +2,11 @@
 
 void __attribute__((weak)) rewind(FILE *stream)
 {
+    if (stream == NULL || stream == stdin || stream == stdout || stream == stderr)
+    {
+        return;
+    }
+
     stream->eof = 0;
 
     (void)fseek(stream, 0L, SEEK_SET);

test/standalone/asprintf_fprintf/src/main.c

@@ -536,19 +536,20 @@ int memccpy_tests(void) {
     for (size_t i = 0; i != sizeof terminal; ++i) {
         void* to = T_memccpy(dest, src, terminal[i], sizeof dest);
 
-        fprintf(file, "Terminal '%c' (%s):\t\"", terminal[i], to ? "found" : "absent");
+        C(fprintf(file, "Terminal '%c' (%s):\t\"", terminal[i], to ? "found" : "absent") > 0);
 
         // if `terminal` character was not found - print the whole `dest`
         to = to ? to : dest + sizeof dest;
 
         for (char* from = dest; from != to; ++from) {
-            fputc(isprint(*from) ? *from : alt, file);
+            unsigned char ch = (unsigned char)(isprint(*from) ? *from : alt);
+            C(fputc((int)ch, file) == (int)ch);
         }
 
-        fputs("\"\n", file);
+        C(fputs("\"\n", file) >= 0);
     }
 
-    fprintf(file, "%c%s", '\n', "Separate star names from distances (ly):\n");
+    C(fprintf(file, "%c%s", '\n', "Separate star names from distances (ly):\n") > 0);
     const char *star_distance[] = {
         "Arcturus : 37", "Vega : 25", "Capella : 43", "Rigel : 860", "Procyon : 11"
     };
@@ -566,14 +567,14 @@ int memccpy_tests(void) {
 
     if (first) {
         *first = '\0';
-        fprintf(file, "%s%c", names_only, '\n');
+        C(fprintf(file, "%s%c", names_only, '\n') > 0);
     } else {
         printf("Error Buffer is too small.\n");
     }
 
-    fseek(file, 0, SEEK_END);
+    C(fseek(file, 0, SEEK_END) == 0);
     int file_size = ftell(file);
-    fseek(file, 0, SEEK_SET);
+    C(fseek(file, 0, SEEK_SET) == 0);
 
     if (file_size <= 0) {
         perror("file_size <= 0");
@@ -1687,9 +1688,11 @@ int run_tests(void) {
     /* nano_fprintf memccpy */
         ret = memccpy_tests();
         free(buf); buf = NULL;
-        fclose(file);
+        if (fclose(file) != 0) {
+            perror("Could not close file");
+        }
         if (remove(file_name) != 0) {
-            perror("Couldn't delete file");
+            perror("Could not delete file");
         }
         if (ret != 0) { return ret; }