Get read working a little bit more. Need to handle edge cases!

sw/kernel/filesystems/fat32.h

@@ -45,8 +45,8 @@ int8_t fat32_read_cluster(uint32_t cluster, void* buf);
 uint32_t fat32_next_cluster(uint32_t cluster);
 
 int8_t fat32_file_open(const char* filename);
-int8_t fat32_file_read(int8_t fd, void* buf, size_t nbytes);
+size_t fat32_file_read(int8_t fd, void* buf, size_t nbytes);
-int8_t fat32_file_write(int8_t fd, const void* buf, size_t nbytes);
+size_t fat32_file_write(int8_t fd, const void* buf, size_t nbytes);
 int8_t fat32_file_close(int8_t fd);
 
 #endif

sw/kernel/filesystems/fat32_c.c

@@ -13,7 +13,7 @@ int8_t fd_val;
 
 
 //TODO
-int8_t fat32_file_write(int8_t fd, const void* buf, size_t nbytes) {
+size_t fat32_file_write(int8_t fd, const void* buf, size_t nbytes) {
     (void)fd;
     (void)buf;
     (void)nbytes;
@@ -62,7 +62,7 @@ int8_t fat32_file_open(const char* filename) {
     return fd;
 }
 
-int8_t fat32_file_read(int8_t fd, void* buf, size_t nbytes) {
+size_t fat32_file_read(int8_t fd, void* buf, size_t nbytes) {
     uint16_t i;
     uint8_t error;
     size_t offset;
@@ -84,11 +84,17 @@ int8_t fat32_file_read(int8_t fd, void* buf, size_t nbytes) {
     for (i = 0; i < cluster_seq; i++) {
         cluster = fat32_next_cluster(cluster);
     }
+
+    offset = fdesc->file_pos % 512;
+
+    if (offset + nbytes > 512) {
+        cprintf("Need to do something about this!\n");
+    }
     
     fat32_read_cluster(cluster, sd_buf);
-    memcpy(buf, sd_buf, nbytes);
+    memcpy(buf, sd_buf + offset, nbytes);
     fdesc->file_pos += nbytes;
-    return error;
+    return nbytes;
 }
 
 int8_t fat32_read_cluster(uint32_t cluster, void* buf) {

sw/kernel/filesystems/fs.h

@@ -7,14 +7,14 @@
 #include <process/process.h>
 
 /* syscalls for files */
-int8_t file_read(int8_t fd, void* buf, size_t nbytes);
+size_t file_read(int8_t fd, void* buf, size_t nbytes);
-int8_t file_write(int8_t fd, const void* buf, size_t nbytes);
+size_t file_write(int8_t fd, const void* buf, size_t nbytes);
 int8_t file_open(const char* filename);
 int8_t file_close(int8_t fd);
 
 /* syscalls for directories */
-int8_t directory_read(int8_t fd, void* buf, size_t nbytes);
+size_t directory_read(int8_t fd, void* buf, size_t nbytes);
-int8_t directory_write(int8_t fd, const void* buf, size_t nbytes);
+size_t directory_write(int8_t fd, const void* buf, size_t nbytes);
 int8_t directory_open(const char* filename);
 int8_t directory_close(int8_t fd);
 

sw/kernel/process/process.h

@@ -15,8 +15,8 @@
 struct fops {
     int8_t (*open)(const char* filename);
     int8_t (*close)(int8_t fd);
-    int8_t (*read)(int8_t fd, void* buf, size_t nbytes);
+    size_t (*read)(int8_t fd, void* buf, size_t nbytes);
-    int8_t (*write)(int8_t fd, const void* buf, size_t nbytes);
+    size_t (*write)(int8_t fd, const void* buf, size_t nbytes);
 };
 
 struct file_desc {

sw/test_code/fs_test/main.c

@@ -9,14 +9,15 @@ char data [256];
 int main(void) {
     int8_t fd;
     size_t i;
+    size_t nbytes;
     fat32_init();
 
     /* This is what is going to be part of open */
     fd = fat32_file_open("VERYLA~1TXT");
     cprintf("fd: %x\n", fd);
 
-    while (fat32_file_read(fd, data, 256)){
+    while ((nbytes = fat32_file_read(fd, data, 256))){
-        for (i = 0; i < 256; i++) {
+        for (i = 0; i < nbytes; i++) {
             cprintf("%c", data[i]);
         }
     }