Add basic symlink support.

- sys$readlink + readlink()
- Add a /proc/PID/exe symlink to the process's executable.
- Print symlink contents in ls output.
- Some work on plumbing options into VFS::open().

LibC/dirent.cpp

@@ -8,8 +8,7 @@ extern "C" {
 
 DIR* opendir(const char* name)
 {
-    // FIXME: Should fail if it's not a directory!
-    int fd = open(name);
+    int fd = open(name, O_RDONLY | O_DIRECTORY);
     if (fd == -1)
         return nullptr;
     DIR* dirp = (DIR*)malloc(sizeof(dirp));

LibC/unistd.cpp

@@ -20,10 +20,9 @@ pid_t getpid()
     return Syscall::invoke(Syscall::PosixGetpid);
 }
 
-int open(const char* path)
+int open(const char* path, int options)
 {
-    size_t length = strlen(path);
-    int rc = Syscall::invoke(Syscall::PosixOpen, (dword)path, (dword)length);
+    int rc = Syscall::invoke(Syscall::PosixOpen, (dword)path, (dword)options);
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
@@ -74,5 +73,11 @@ int gethostname(char* buffer, size_t size)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+ssize_t readlink(const char* path, char* buffer, size_t size)
+{
+    int rc = Syscall::invoke(Syscall::PosixReadlink, (dword)path, (dword)buffer, (dword)size);
+    __RETURN_WITH_ERRNO(rc, rc, -1);
+}
+
 }
 

LibC/unistd.h

@@ -7,7 +7,7 @@ extern "C" {
 uid_t getuid();
 gid_t getgid();
 pid_t getpid();
-int open(const char* path);
+int open(const char* path, int options);
 ssize_t read(int fd, void* buf, size_t count);
 int close(int fd);
 pid_t waitpid(pid_t, int* wstatus, int options);
@@ -16,6 +16,7 @@ char* getcwd(char* buffer, size_t size);
 int lstat(const char* path, stat* statbuf);
 int sleep(unsigned seconds);
 int gethostname(char*, size_t);
+ssize_t readlink(const char* path, char* buffer, size_t);
 
 #define WEXITSTATUS(status) (((status) & 0xff00) >> 8)
 #define WTERMSIG(status) ((status) & 0x7f)
@@ -52,4 +53,10 @@ int gethostname(char*, size_t);
 #define S_ISFIFO(m) (((m) & S_IFMT) == S_IFIFO)
 #define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK)
 
+#define O_RDONLY 0
+#define O_WRONLY 1
+#define O_RDWR 2
+#define O_DIRECTORY 00200000
+#define O_NOFOLLOW 00400000
+
 }