From 0c5b9e78200d8a70addfb3a2e47051f800e54fb0 Mon Sep 17 00:00:00 2001
From: Dietmar Maurer <dietmar@proxmox.com>
Date: Sat, 16 Jan 2021 15:15:54 +0100
Subject: [PATCH] tape: sgutils2.rs - add do_out_command()

Make it possible to run commands that writes data.
---
 src/tape/sgutils2.rs | 112 +++++++++++++++++++++++++++++++++++++------
 1 file changed, 97 insertions(+), 15 deletions(-)

diff --git a/src/tape/sgutils2.rs b/src/tape/sgutils2.rs
index 30826074..464acbd9 100644
--- a/src/tape/sgutils2.rs
+++ b/src/tape/sgutils2.rs
@@ -16,6 +16,12 @@ impl Drop for SgPtBase  {
     }
 }
 
+pub const SCSI_PT_RESULT_GOOD:c_int = 0;
+pub const SCSI_PT_RESULT_STATUS:c_int = 1;
+pub const SCSI_PT_RESULT_SENSE:c_int = 2;
+pub const SCSI_PT_RESULT_TRANSPORT_ERR:c_int = 3;
+pub const SCSI_PT_RESULT_OS_ERR:c_int = 4;
+
 #[link(name = "sgutils2")]
 extern {
 
@@ -39,6 +45,12 @@ extern {
         dxfer_ilen: c_int,
     );
 
+    pub fn set_scsi_pt_data_out(
+        objp: *mut SgPtBase,
+        dxferp: *const u8,
+        dxfer_olen: c_int,
+    );
+
     pub fn set_scsi_pt_cdb(
         objp: *mut SgPtBase,
         cdb: *const u8,
@@ -63,6 +75,8 @@ extern {
     pub fn get_scsi_pt_sense_len(objp: *const SgPtBase) -> c_int;
 
     pub fn get_scsi_pt_status_response(objp: *const SgPtBase) -> c_int;
+
+    pub fn get_scsi_pt_result_category(objp: *const SgPtBase) -> c_int;
 }
 
 /// Creates a Box<SgPtBase>
@@ -87,6 +101,19 @@ pub struct SgRaw<'a, F> {
     sense_buffer: [u8; 32],
 }
 
+// alloc page aligned buffer
+pub fn alloc_page_aligned_buffer(buffer_size: usize) -> Result<Box<[u8]> , Error> {
+    let page_size = unsafe { libc::sysconf(libc::_SC_PAGESIZE) } as usize;
+    let layout = std::alloc::Layout::from_size_align(buffer_size, page_size)?;
+    let dinp = unsafe { std::alloc::alloc_zeroed(layout) };
+    if dinp.is_null() {
+        bail!("alloc SCSI output buffer failed");
+    }
+
+    let buffer_slice = unsafe { std::slice::from_raw_parts_mut(dinp, buffer_size)};
+    Ok(unsafe { Box::from_raw(buffer_slice) })
+}
+
 impl <'a, F: AsRawFd> SgRaw<'a, F> {
 
     /// Create a new instance to run commands
@@ -94,15 +121,13 @@ impl <'a, F: AsRawFd> SgRaw<'a, F> {
     /// The file must be a handle to a SCSI device.
     pub fn new(file: &'a mut F, buffer_size: usize) -> Result<Self, Error> {
 
-        let page_size = unsafe { libc::sysconf(libc::_SC_PAGESIZE) } as usize;
-        let layout = std::alloc::Layout::from_size_align(buffer_size, page_size)?;
-        let dinp = unsafe { std::alloc::alloc(layout) };
-        if dinp.is_null() {
-            bail!("alloc SCSI output buffer failed");
-        }
+        let buffer;
 
-        let buffer = unsafe { std::slice::from_raw_parts_mut(dinp, buffer_size)};
-        let buffer = unsafe { Box::from_raw(buffer) };
+        if buffer_size > 0 {
+            buffer = alloc_page_aligned_buffer(buffer_size)?;
+        } else {
+            buffer =  Box::new([]);
+        }
 
         let sense_buffer = [0u8; 32];
 
@@ -114,13 +139,15 @@ impl <'a, F: AsRawFd> SgRaw<'a, F> {
 
         let mut ptvp = boxed_scsi_pt_obj()?;
 
-        unsafe {
-            set_scsi_pt_data_in(
-                &mut *ptvp,
-                self.buffer.as_ptr(),
-                self.buffer.len() as c_int,
-            )
-        };
+        if self.buffer.len() > 0 {
+            unsafe {
+                set_scsi_pt_data_in(
+                    &mut *ptvp,
+                    self.buffer.as_ptr(),
+                    self.buffer.len() as c_int,
+                )
+            };
+        }
 
         unsafe {
             set_scsi_pt_sense(
@@ -140,6 +167,10 @@ impl <'a, F: AsRawFd> SgRaw<'a, F> {
             bail!("no valid SCSI command");
         }
 
+        if self.buffer.len() < 16 {
+            bail!("output buffer too small");
+        }
+
         let mut ptvp = self.create_boxed_scsi_pt_obj()?;
 
         unsafe {
@@ -176,4 +207,55 @@ impl <'a, F: AsRawFd> SgRaw<'a, F> {
 
         Ok(&self.buffer[..data_len])
     }
+
+    /// Run dataout command
+    ///
+    /// Note: use alloc_page_aligned_buffer to alloc data transfer buffer
+    pub fn do_out_command(&mut self, cmd: &[u8], data: &[u8]) -> Result<(), Error> {
+
+        if !unsafe { sg_is_scsi_cdb(cmd.as_ptr(), cmd.len() as c_int) } {
+            bail!("no valid SCSI command");
+        }
+
+        let page_size = unsafe { libc::sysconf(libc::_SC_PAGESIZE) } as usize;
+        if ((data.as_ptr() as usize) & (page_size -1)) != 0 {
+            bail!("wrong transfer buffer alignment");
+        }
+
+        let mut ptvp = self.create_boxed_scsi_pt_obj()?;
+
+        unsafe {
+            set_scsi_pt_data_out(
+                &mut *ptvp,
+                data.as_ptr(),
+                data.len() as c_int,
+            );
+
+            set_scsi_pt_cdb(
+                &mut *ptvp,
+                cmd.as_ptr(),
+                cmd.len() as c_int,
+            );
+         };
+
+        let res = unsafe { do_scsi_pt(&mut *ptvp, self.file.as_raw_fd(), 0, 0) };
+        if res < 0 {
+            let err = nix::Error::last();
+            bail!("do_scsi_pt failed  - {}", err);
+        }
+        if res != 0 {
+            bail!("do_scsi_pt failed {}", res);
+        }
+
+        // todo: what about sense data?
+        let _sense_len = unsafe { get_scsi_pt_sense_len(&mut *ptvp) };
+
+        let status = unsafe { get_scsi_pt_status_response(&mut *ptvp) };
+        if status != 0 {
+            // toto: improve error reporting
+            bail!("unknown scsi error - status response {}", status);
+        }
+
+        Ok(())
+    }
 }