Add new syscall: getcwd

This patch adds a new getcwd() syscall that returns the current working
directory to userspace. The implementation is lame because current directory is
tied to an inode instead of a dentry, and there's no way to look up the full
dentry chain.

But whatever, it's a decent start.

Signed-off-by: Pekka Enberg <[email protected]>

fs/inode.c

@@ -169,3 +169,8 @@ int inode_rm(char *path)
 	}
 	return r;
 }
+
+int inode_get_pathname(struct inode *inode, char *pathname, size_t len)
+{
+	return inode->i_ops->get_pathname(inode, pathname, len);
+}

fs/minix/inode.c

@@ -481,6 +481,24 @@ void minix_inode_stat(struct inode *inode, struct file_stat *stat)
 	stat->link = i2mdi(inode)->i_nlinks;
 }
 
+int minix_get_pathname(struct inode *inode, char *pathname, size_t len)
+{
+	struct minix_dentry *de;
+
+	if (len < MINIX_NAME_LEN + 1)
+		return -1;
+
+	de = minix_lookup_dentry(inode, ".", 1, NULL);
+	if (!de)
+		return -1;
+
+	strncpy(pathname, de->d_name, MINIX_NAME_LEN);
+
+	pathname[MINIX_NAME_LEN] = '\0';
+
+	return 0;
+}
+
 void minix_inode_truncate(struct inode *inode)
 {
 	bmap_put_blocks(inode);
@@ -528,6 +546,7 @@ static struct inode_operations minix_dir_iops = {
 	.create = minix_inode_create,
 	.rm = minix_inode_rm,
 	.stat = minix_inode_stat,
+	.get_pathname = minix_get_pathname,
 };
 
 /* regular file operations */

fs/sys.c

@@ -1,5 +1,7 @@
+#include <inode.h>
 #include <print.h>
 #include <file.h>
+#include <slab.h>
 #include <task.h>
 #include <fs.h>
 
@@ -201,3 +203,14 @@ int sys_truncate(int fd)
 	put_file(file);
 	return r;
 }
+
+int sys_getcwd(char *buf, size_t size)
+{
+	struct inode *inode;
+
+	inode = ctask->fs.current_dir;
+	if (!inode)
+		return -1;
+
+	return inode_get_pathname(inode, buf, size);
+}

include/inode.h

@@ -23,6 +23,7 @@ struct inode_operations {
 	int (*rm)(struct inode *, char *, int);
 	void (*stat)(struct inode *, struct file_stat *);
 	void (*truncate)(struct inode *);
+	int (*get_pathname)(struct inode *, char *, size_t);
 };
 
 struct inode {
@@ -58,5 +59,6 @@ extern int inode_rmdir(char *path);
 extern int inode_rm(char *path);
 extern struct inode *inode_sub_lookup_put(struct inode *, char *, int);
 extern int inode_truncate(struct inode *);
+extern int inode_get_pathname(struct inode *, char *, size_t);
 
 #endif	/* inode.h */

include/syscall.h

@@ -30,7 +30,8 @@ typedef u32 (*syscall_t)(u32, u32, u32, u32, u32);
 #define SYS_rmdir	20
 #define SYS_rm		21
 #define SYS_truncate	22
-#define SYS_CALL_MAX	22
+#define SYS_getcwd	23
+#define SYS_CALL_MAX	23
 
 extern int sys_puts(char *);
 extern int sys_gets(char *, int);
@@ -54,5 +55,6 @@ extern void sys_sync(void);
 extern int sys_rmdir(char *);
 extern int sys_rm(char *);
 extern int sys_truncate(int);
+extern int sys_getcwd(char *buf, size_t size);
 
 #endif	/* syscall.h */

kernel/syscall.c

@@ -27,6 +27,7 @@ static syscall_t sys_call_table[SYS_CALL_MAX + 1] = {
 	__sys_call_entry(rmdir),
 	__sys_call_entry(rm),
 	__sys_call_entry(truncate),
+	__sys_call_entry(getcwd),
 };
 
 void do_sys_call(struct regs *reg)

user/include/syscall.h

@@ -30,6 +30,7 @@ struct dir_stat;
 #define SYS_rmdir	20
 #define SYS_rm		21
 #define SYS_truncate	22
+#define SYS_getcwd	23
 
 extern int usys_puts(char *);
 extern int usys_gets(char *, int);
@@ -53,5 +54,6 @@ extern void usys_sync(void);
 extern int usys_rmdir(char *);
 extern int usys_rm(char *);
 extern int usys_truncate(int);
+extern int usys_getcwd(char *buf, size_t size);
 
 #endif	/* syscall.h */

user/include/ulib.h

@@ -30,6 +30,7 @@ extern int rmdir(char *);
 extern int rm(char *);
 extern void sync(void);
 extern int truncate(int);
+extern char *getcwd(char *buf, size_t size);
 
 #define S_IFMT		00170000
 #define S_IFSOCK	0140000

user/libc/file.c

@@ -95,3 +95,11 @@ int truncate(int fd)
 {
 	return usys_truncate(fd);
 }
+
+char *getcwd(char *buf, size_t size)
+{
+	if (usys_getcwd(buf, size))
+		return NULL;
+
+	return buf;
+}

user/libc/syscall.c

@@ -128,3 +128,8 @@ int usys_truncate(int fd)
 {
 	return usyscall(SYS_truncate, (u32)fd, 0, 0, 0, 0);
 }
+
+int usys_getcwd(char *buf, size_t size)
+{
+	return usyscall(SYS_getcwd, (u32)buf, (u32)size, 0, 0, 0);
+}