Covert sys_mkdir to sys_mkdirat

5c31e01c · Silas Boyd-Wickizer · d2e856e0 · 5c31e01c · 5c31e01c · 5c31e01c
--- a/include/kern_c.h
+++ b/include/kern_c.h
@@ -29,7 +29,7 @@ long sys_fstat(int, struct stat*);
 long sys_getpid(void);
 long sys_kill(int);
 long sys_link(const char*, const char*);
-long sys_mkdir(const char*);
+long sys_mkdirat(int, const char*);
 long sys_mknod(const char*, int, int);
 long sys_openat(int, const char*, int);
 long sys_pipe(int*);

--- a/include/syscall.h
+++ b/include/syscall.h
@@ -13,7 +13,7 @@
 #define SYS_unlink 12
 #define SYS_fstat  13
 #define SYS_link   14
-#define SYS_mkdir  15
+#define SYS_mkdirat 15
 #define SYS_chdir  16
 #define SYS_dup    17
 #define SYS_getpid 18

--- a/include/user.h
+++ b/include/user.h
@@ -18,6 +18,7 @@ int unlink(const char*);
 int fstat(int fd, struct stat*);
 int link(const char*, const char*);
 int mkdir(const char*);
+int mkdirat(int dirfd, const char *pathname);
 int chdir(const char*);
 int dup(int);
 int getpid(void);

--- a/kernel/bootdata.c
+++ b/kernel/bootdata.c
@@ -39,7 +39,7 @@ long (*syscalls[])(u64, u64, u64, u64, u64) = {
  SYSCALL(getpid),
  SYSCALL(kill),
  SYSCALL(link),
-  SYSCALL(mkdir),
+  SYSCALL(mkdirat),
  SYSCALL(mknod),
  SYSCALL(openat),
  SYSCALL(pipe),

--- a/kernel/sysfile.cc
+++ b/kernel/sysfile.cc
@@ -328,11 +328,25 @@ sys_openat(int dirfd, const char *path, int omode)
 }

 long
-sys_mkdir(const char *path)
+sys_mkdirat(int dirfd, const char *path)
 {
+  struct inode *cwd;
  struct inode *ip;

-  if(argcheckstr(path) < 0 || (ip = create(myproc()->cwd, path, T_DIR, 0, 0)) == 0)
+  if (dirfd == AT_FDCWD) {
+    cwd = myproc()->cwd;
+  } else {
+    // XXX(sbw) do we need the sref while we touch fdir->ip?
+    sref<file> fdir;
+    if (!getfile(dirfd, &fdir) || fdir->type != file::FD_INODE)
+      return -1;
+    cwd = fdir->ip;
+  }
+
+  if (argcheckstr(path) < 0)
+    return -1;
+  ip = create(cwd, path, T_DIR, 0, 0);
+  if (ip == nullptr)
    return -1;
  iunlockput(ip);
  return 0;

--- a/lib/ulib.c
+++ b/lib/ulib.c
@@ -151,6 +151,12 @@ open(const char *path, int omode)
  return openat(AT_FDCWD, path, omode);
 }

+int
+mkdir(const char *path)
+{
+  return mkdirat(AT_FDCWD, path);
+}
+
 extern void __cxa_pure_virtual(void);
 void __cxa_pure_virtual(void)
 { 

--- a/lib/usys.S
+++ b/lib/usys.S
@@ -30,7 +30,7 @@ SYSCALL(mknod)
 SYSCALL(unlink)
 SYSCALL(fstat)
 SYSCALL(link)
-SYSCALL(mkdir)
+SYSCALL(mkdirat)
 SYSCALL(chdir)
 SYSCALL(dup)
 SYSCALL(getpid)