M include/cedos/fat.h → include/cedos/fat.h

@@ -9,6 +9,7 @@ void FAT_init();
 int FAT_dir_next(file_t *file, int index, char *fname_buffer);
 int FAT_openat(file_t *root, file_t *handle, const char *fname, int flags);
 uint32_t FAT_read(file_t *file, uint8_t *buffer, uint32_t count);
+off_t FAT_lseek(file_t *file, off_t offset, int whence);
 
 extern file_operations_t FAT_fops;
 

M include/cedos/file.h → include/cedos/file.h

@@ -6,6 +6,11 @@
 #include "cedos/mm/paging.h"
 
 typedef uint32_t fpos_t;
+typedef int32_t off_t;
+
+#define SEEK_SET 0
+#define SEEK_CUR 1
+#define SEEK_END 2
 
 struct file;
 struct file_operations;
@@ -26,12 +31,14 @@ int (*openat)(file_t *root, file_t *handle, const char *fname, int flags);
     int (*read)(file_t *file, char *buffer, uint32_t size);
     int (*write)(file_t *file, char *buffer, uint32_t size);
     int (*dir_next)(file_t *file, int index, char *fname_buffer);
+    off_t (*lseek)(file_t *file, off_t offset, int whence);
 };
 
 int file_init();
 int file_open(const char *pathname, int flags);
 int file_openat(int fd, const char *fname, int flags);
 int file_read(int fd, char *buffer, uint32_t size);
+off_t file_lseek(int fd, off_t offset, int whence);
 int file_write(int fd, char *buffer, uint32_t size);
 int file_dir_next(int fd, int index, char *fname_buffer);
 

M src/kernel/drivers/tty.c → src/kernel/drivers/tty.c

@@ -9,7 +9,8 @@ tty_open,       /* open */
     tty_openat,     /* openat */
     tty_read,       /* read */
     tty_write,      /* write */
-    NULL            /* dir_next */
+    NULL,           /* dir_next */
+    NULL            /* lseek */
 }; 
 
 int tty_open(const char *pathname, int flags) {

M src/kernel/fat.c → src/kernel/fat.c

@@ -12,7 +12,8 @@ NULL,           /* open */
     FAT_openat,     /* openat */
     FAT_read,       /* read */
     NULL,           /* write */
-    FAT_dir_next    /* dir_next */
+    FAT_dir_next,   /* dir_next */
+    FAT_lseek       /* lseek */
 };
 
 typedef struct {
@@ -220,6 +221,7 @@ if (i <= 0) { return -1; }
 
         if (strcmp(buffer, fname) == 0) {
             // file found
+            handle->pos = 0;
             handle->fops = &FAT_fops;
             handle->fat_cluster = first_cluster;
             return 0;
@@ -229,7 +231,7 @@ }
 
 uint32_t FAT_read(file_t *file, uint8_t *buffer, uint32_t count) {
     uint16_t cluster = file->fat_cluster;
-    fpos_t offset = 0; //file->pos;
+    fpos_t offset = file->pos;
     uint32_t size = 0;
 
     uint32_t cluster_size = boot_sect->bytes_per_sect * boot_sect->sect_per_cluster;
@@ -263,5 +265,19 @@ buffer += memcpy_size;
         size += memcpy_size;
     }
 
+    file->pos += size;
+
     return size;
+}
+
+off_t FAT_lseek(file_t *file, off_t offset, int whence) {
+    if (whence == SEEK_SET) {
+        file->pos = offset;
+    } else if (whence == SEEK_CUR) {
+        file->pos += offset;
+    } else if (whence == SEEK_END) {
+        // to be implemented
+    } else {
+        kpanic("Wrong whence!");
+    }
 }

M src/kernel/file.c → src/kernel/file.c

@@ -109,3 +109,11 @@ if (file->fops->dir_next == NULL) { return -1; }
 
     file->fops->dir_next(file, index, fname_buffer);
 }
+
+off_t file_lseek(int fd, off_t offset, int whence) {
+    file_t *file = get_process_local_file(fd);
+
+    if (file->fops->lseek == NULL) { return -1; }
+
+    return file->fops->lseek(file, offset, whence);
+}

M src/kernel/pipe.c → src/kernel/pipe.c

@@ -7,7 +7,8 @@ NULL,           /* open */
     NULL,           /* openat */
     pipe_read,      /* read */
     pipe_write,     /* write */
-    NULL            /* dir_next */
+    NULL,           /* dir_next */
+    NULL            /* lseek */
 };
 
 #define PIPE_BUFFER_SIZE 512