Convert directory reading to generic stream

src/kernel/fat16.c

@@ -205,39 +205,80 @@ typedef struct {
   stream_t stream;
   fs_node_t *node;
   uint64_t offset;
-} fat16_stream_t;
+} fat16_file_stream_t;
 
-static uint64_t stream_write(__attribute__((unused)) const stream_t *self, __attribute__((unused)) const char *from,
-                             __attribute__((unused)) uint64_t bytes) {
+static uint64_t file_stream_write(__attribute__((unused)) const stream_t *self, __attribute__((unused)) const char *from,
+                                  __attribute__((unused)) uint64_t bytes) {
   return (uint64_t)-1;
 }
 
-static uint64_t stream_read(const stream_t *self, uint64_t max, char *to) {
-  fat16_stream_t *fss = (fat16_stream_t *)self;
-  if (fss->offset >= fss->node->size) {
+static uint64_t file_stream_read(const stream_t *self, uint64_t max, char *to) {
+  fat16_file_stream_t *ffs = (fat16_file_stream_t *)self;
+  if (ffs->offset >= ffs->node->size) {
     return 0;
   }
-  uint64_t remaining = fss->node->size - fss->offset;
+  uint64_t remaining = ffs->node->size - ffs->offset;
   uint64_t to_read = remaining > max ? max : remaining;
-  fat16_read(fss->node, fss->offset, to_read, to);
-  fss->offset += to_read;
+  fat16_read(ffs->node, ffs->offset, to_read, to);
+  ffs->offset += to_read;
   return to_read;
 }
 
-static void stream_close(stream_t *self) {
-  fat16_stream_t *fss = (fat16_stream_t *)self;
-  fat16_close(fss->node);
+static void file_stream_close(stream_t *self) {
+  fat16_file_stream_t *ffs = (fat16_file_stream_t *)self;
+  fat16_close(ffs->node);
+  memory_free(self);
+}
+
+typedef struct {
+  stream_t stream;
+  fs_node_t *node;
+  uint64_t index;
+} fat16_directory_stream_t;
+
+static uint64_t directory_stream_write(__attribute__((unused)) const stream_t *self, __attribute__((unused)) const char *from,
+                                       __attribute__((unused)) uint64_t bytes) {
+  return (uint64_t)-1;
+}
+
+static uint64_t directory_stream_read(const stream_t *self, uint64_t max, char *to) {
+  fat16_directory_stream_t *fds = (fat16_directory_stream_t *)self;
+  fs_node_t *node = fat16_open_at(fds->node, fds->index++);
+  if (!node) {
+    return 0;
+  }
+  uint64_t length = string_length(node->name);
+  uint64_t to_read = length + 1 > max ? max : length + 1;
+  memory_copy(node->name, to_read, to);
+  to[max - 1] = '\0';
+
+  return to_read;
+}
+
+static void directory_stream_close(stream_t *self) {
+  fat16_directory_stream_t *fds = (fat16_directory_stream_t *)self;
+  fat16_close(fds->node);
   memory_free(self);
 }
 
 stream_t *fat16_open_stream(const fs_node_t *source) {
-  fat16_stream_t *result = memory_allocate(sizeof(fat16_node_t));
-  result->stream.read = stream_read;
-  result->stream.write = stream_write;
-  result->stream.close = stream_close;
-  result->node = fat16_open_again(source);
-  result->offset = 0;
-  return (stream_t *)result;
+  if (!source->is_dir) {
+    fat16_file_stream_t *result = memory_allocate(sizeof(fat16_file_stream_t));
+    result->stream.read = file_stream_read;
+    result->stream.write = file_stream_write;
+    result->stream.close = file_stream_close;
+    result->node = fat16_open_again(source);
+    result->offset = 0;
+    return (stream_t *)result;
+  } else {
+    fat16_directory_stream_t *result = memory_allocate(sizeof(fat16_directory_stream_t));
+    result->stream.read = directory_stream_read;
+    result->stream.write = directory_stream_write;
+    result->stream.close = directory_stream_close;
+    result->node = fat16_open_again(source);
+    result->index = 0;
+    return (stream_t *)result;
+  }
 }
 
 void fat16_read(const fs_node_t *file, uint64_t offset, uint64_t size, void *to) {

src/kernel/syscall.c

@@ -152,31 +152,6 @@ static exit_code_t spawn(const char *path, uint64_t argc, const char **argv) {
   return code;
 }
 
-static uint64_t readdir(const char *path, uint64_t index, uint64_t max, char *to) {
-  fs_node_t *dir = path_open_directory(current_process->root, current_process->cwd, path);
-  if (!dir) {
-    return (uint64_t)-1;
-  }
-  fs_node_t *item = fs_open_at(dir, index);
-  if (!item) {
-    if (dir != current_process->root) {
-      fs_close(dir);
-    }
-    return 0;
-  }
-  uint64_t length = string_length(item->name);
-  uint64_t size = length > max - 1 ? max - 1 : length;
-  memory_copy(item->name, size, to);
-  to[size] = '\0';
-
-  fs_close(item);
-  if (dir != current_process->root) {
-    fs_close(dir);
-  }
-
-  return size;
-}
-
 static uint64_t open(const char *path) {
   if (current_process->free_fd >= MAX_FDS) {
     return (uint64_t)-1;
@@ -203,7 +178,7 @@ static void exit(exit_code_t code) {
   process_switch_to(&current_process->kernel_rsp, current_process->parent->kernel_rsp, VIRT_TO_PHYS(current_process->parent->pml4));
 }
 
-uint64_t syscall_dispatch(uint64_t func, uint64_t arg1, uint64_t arg2, uint64_t arg3, uint64_t arg4) {
+uint64_t syscall_dispatch(uint64_t func, uint64_t arg1, uint64_t arg2, uint64_t arg3, __attribute__((unused)) uint64_t arg4) {
   switch (func) {
   case SYSCALL_READ:
     return read(arg1, arg2, (char *)arg3);
@@ -215,8 +190,6 @@ uint64_t syscall_dispatch(uint64_t func, uint64_t arg1, uint64_t arg2, uint64_t
     return chdir((const char *)arg1);
   case SYSCALL_SPAWN:
     return spawn((const char *)arg1, arg2, (const char **)arg3);
-  case SYSCALL_READDIR:
-    return readdir((const char *)arg1, arg2, arg3, (char *)arg4);
   case SYSCALL_OPEN:
     return open((const char *)arg1);
   case SYSCALL_CLOSE:

src/kernel/syscall.h

@@ -7,7 +7,6 @@
 #define SYSCALL_GETCWD 2
 #define SYSCALL_CHDIR 3
 #define SYSCALL_SPAWN 4
-#define SYSCALL_READDIR 5
 #define SYSCALL_OPEN 6
 #define SYSCALL_CLOSE 7
 #define SYSCALL_EXIT 60

src/user/app/ls/ls.c

@@ -6,21 +6,28 @@
 #define PRINT_D(s) write(1, s, string_length(s));
 
 exit_code_t ls(const char *path) {
-  uint64_t i = 0;
-  while (1) {
-    char out[100];
-    uint64_t s = readdir(path, i, 100, out);
-    if (!s) {
-      return EXIT_CODE_OK;
-    }
-    if (s == (uint64_t)-1) {
-      PRINT_S("ls: path does not exist\n");
+  uint64_t fd = open(path);
+
+  if (fd == (uint64_t)-1) {
+    PRINT_S("ls: path does not exist\n");
+    return EXIT_CODE_GENERAL_FAILURE;
+  }
+
+  char buffer[100];
+  uint64_t bytes;
+  while ((bytes = read(fd, 100, buffer))) {
+    if (bytes == (uint64_t)-1) {
+      PRINT_S("ls: could not read directory\n");
+      close(fd);
       return EXIT_CODE_GENERAL_FAILURE;
     }
-    PRINT_D(out);
+    write(1, buffer, bytes - 1);
     PRINT_S("\n");
-    i++;
   }
+
+  close(fd);
+
+  return 0;
 }
 
 exit_code_t main(uint64_t argc, const char **argv) {

src/user/syscall.asm

@@ -30,13 +30,6 @@ spawn:
     syscall
     ret
 
-global readdir
-readdir:
-    mov r10, rcx
-    mov rax, 5
-    syscall
-    ret
-
 global open
 open:
     mov rax, 6

src/user/syscall.h

@@ -13,8 +13,6 @@ uint64_t chdir(const char *path);
 
 exit_code_t spawn(const char *path, uint64_t argc, const char **argv);
 
-uint64_t readdir(const char *path, uint64_t index, uint64_t max, char *to);
-
 uint64_t open(const char *path);
 
 uint64_t close(uint64_t fd);