From f191b84b5032880f17d3a8973a3b6b21048013dc Mon Sep 17 00:00:00 2001
From: Luke Payne <1432762+lukepayne@users.noreply.github.com>
Date: Sun, 26 Apr 2020 15:59:47 +1000
Subject: [PATCH] Kernel: Added the ability to set the hostname via new syscall
 Userland/hostname: Now takes parameter to set the hostname LibC/unistd: Added
 sethostname function

---
 Kernel/Process.cpp        | 12 ++++++++++++
 Kernel/Process.h          |  1 +
 Kernel/Syscall.h          |  1 +
 Libraries/LibC/unistd.cpp |  6 ++++++
 Libraries/LibC/unistd.h   |  1 +
 Shell/GlobalState.h       |  2 +-
 Userland/hostname.cpp     | 26 ++++++++++++++++++--------
 7 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index ec5befdc5ed..c81e9598ed6 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -712,6 +712,18 @@ int Process::sys$gethostname(char* buffer, ssize_t size)
     return 0;
 }
 
+int Process::sys$sethostname(const char* hostname, ssize_t length)
+{
+    REQUIRE_PROMISE(stdio);
+    if (length < 0)
+        return -EINVAL;
+    LOCKER(*s_hostname_lock, Lock::Mode::Shared);
+    if (length > 64)
+        return -ENAMETOOLONG;
+    *s_hostname = validate_and_copy_string_from_user(hostname, length);
+    return 0;
+}
+
 pid_t Process::sys$fork(RegisterState& regs)
 {
     REQUIRE_PROMISE(proc);
diff --git a/Kernel/Process.h b/Kernel/Process.h
index fb9c505e9ce..0727b7d0e74 100644
--- a/Kernel/Process.h
+++ b/Kernel/Process.h
@@ -223,6 +223,7 @@ public:
     int sys$clock_settime(clockid_t, timespec*);
     int sys$clock_nanosleep(const Syscall::SC_clock_nanosleep_params*);
     int sys$gethostname(char*, ssize_t);
+    int sys$sethostname(const char*, ssize_t);
     int sys$uname(utsname*);
     int sys$readlink(const Syscall::SC_readlink_params*);
     int sys$ttyname_r(int fd, char*, ssize_t);
diff --git a/Kernel/Syscall.h b/Kernel/Syscall.h
index c0820c45a9a..b1b8fa130d9 100644
--- a/Kernel/Syscall.h
+++ b/Kernel/Syscall.h
@@ -63,6 +63,7 @@ namespace Kernel {
     __ENUMERATE_SYSCALL(getcwd)               \
     __ENUMERATE_SYSCALL(gettimeofday)         \
     __ENUMERATE_SYSCALL(gethostname)          \
+    __ENUMERATE_SYSCALL(sethostname)          \
     __ENUMERATE_SYSCALL(chdir)                \
     __ENUMERATE_SYSCALL(uname)                \
     __ENUMERATE_SYSCALL(set_mmap_name)        \
diff --git a/Libraries/LibC/unistd.cpp b/Libraries/LibC/unistd.cpp
index 8b03c9df3e5..03c44bd0601 100644
--- a/Libraries/LibC/unistd.cpp
+++ b/Libraries/LibC/unistd.cpp
@@ -352,6 +352,12 @@ int gethostname(char* buffer, size_t size)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+int sethostname(const char* hostname, ssize_t size)
+{
+    int rc = syscall(SC_sethostname, hostname, size);
+    __RETURN_WITH_ERRNO(rc, rc, -1);
+}
+
 ssize_t readlink(const char* path, char* buffer, size_t size)
 {
     Syscall::SC_readlink_params params { { path, strlen(path) }, { buffer, size } };
diff --git a/Libraries/LibC/unistd.h b/Libraries/LibC/unistd.h
index bf8e80068ce..7ed9ebeee8a 100644
--- a/Libraries/LibC/unistd.h
+++ b/Libraries/LibC/unistd.h
@@ -104,6 +104,7 @@ int stat(const char* path, struct stat* statbuf);
 int sleep(unsigned seconds);
 int usleep(useconds_t);
 int gethostname(char*, size_t);
+int sethostname(const char*, ssize_t);
 ssize_t readlink(const char* path, char* buffer, size_t);
 char* ttyname(int fd);
 int ttyname_r(int fd, char* buffer, size_t);
diff --git a/Shell/GlobalState.h b/Shell/GlobalState.h
index 3a92ca34b66..4558447ad20 100644
--- a/Shell/GlobalState.h
+++ b/Shell/GlobalState.h
@@ -36,7 +36,7 @@ struct GlobalState {
     String username;
     String home;
     char ttyname[32];
-    char hostname[32];
+    char hostname[64];
     uid_t uid;
     struct termios termios;
     struct termios default_termios;
diff --git a/Userland/hostname.cpp b/Userland/hostname.cpp
index 15eba021dd1..5015f62a82a 100644
--- a/Userland/hostname.cpp
+++ b/Userland/hostname.cpp
@@ -36,14 +36,24 @@ int main(int argc, char** argv)
         return 1;
     }
 
-    (void)argc;
-    (void)argv;
-    char buffer[HOST_NAME_MAX];
-    int rc = gethostname(buffer, sizeof(buffer));
-    if (rc < 0) {
-        printf("gethostname() error: %s\n", strerror(errno));
-        return 1;
+    if (argc == 1) {
+      char buffer[HOST_NAME_MAX];
+      int rc = gethostname(buffer, sizeof(buffer));
+      if (rc < 0) {
+          printf("gethostname() error: %s\n", strerror(errno));
+          return 1;
+      }
+      printf("%s\n", buffer);
     }
-    printf("%s\n", buffer);
+    else if (argc == 2) {
+      if (strlen(argv[1]) >= HOST_NAME_MAX) {
+        printf("hostname must be less than %i characters\n", HOST_NAME_MAX);
+        return 1;
+      }
+      else {
+        sethostname(argv[1], strlen(argv[1]));
+      }
+    }
+
     return 0;
 }