[thin_metadata_{pack/unpack}] Fix get_nr_blocks()

It didn't work with block devices.

Cargo.lock

@@ -54,6 +54,11 @@ name = "byteorder"
 version = "1.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "cc"
+version = "1.0.54"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "cfg-if"
 version = "0.1.9"
@@ -168,6 +173,18 @@ dependencies = [
  "adler32 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "nix"
+version = "0.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.54 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.71 (registry+https://github.com/rust-lang/crates.io-index)",
+ "void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "nodrop"
 version = "0.1.14"
@@ -368,6 +385,7 @@ dependencies = [
  "crc32c 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "flate2 1.0.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.71 (registry+https://github.com/rust-lang/crates.io-index)",
+ "nix 0.17.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "nom 5.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-derive 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -405,6 +423,11 @@ name = "version_check"
 version = "0.9.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "void"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "wasi"
 version = "0.9.0+wasi-snapshot-preview1"
@@ -438,6 +461,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f8aac770f1885fd7e387acedd76065302551364496e46b3dd00860b2f8359b9d"
 "checksum bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 "checksum byteorder 1.3.4 (registry+https://github.com/rust-lang/crates.io-index)" = "08c48aae112d48ed9f069b33538ea9e3e90aa263cfa3d1c24309612b1f7472de"
+"checksum cc 1.0.54 (registry+https://github.com/rust-lang/crates.io-index)" = "7bbb73db36c1246e9034e307d0fba23f9a2e251faa47ade70c1bd252220c8311"
 "checksum cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)" = "b486ce3ccf7ffd79fdeb678eac06a9e6c09fc88d33836340becb8fffe87c5e33"
 "checksum clap 2.33.1 (registry+https://github.com/rust-lang/crates.io-index)" = "bdfa80d47f954d53a35a64987ca1422f495b8d6483c0fe9f7117b36c2a792129"
 "checksum crc32c 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "77ba37ef26c12988c1cee882d522d65e1d5d2ad8c3864665b88ee92767ed84c5"
@@ -452,6 +476,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)" = "14b6052be84e6b71ab17edffc2eeabf5c2c3ae1fdb464aae35ac50c67a44e1f7"
 "checksum memchr 2.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "3728d817d99e5ac407411fa471ff9800a778d88a24685968b36824eaf4bee400"
 "checksum miniz_oxide 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "aa679ff6578b1cddee93d7e82e263b94a575e0bfced07284eb0c037c1d2416a5"
+"checksum nix 0.17.0 (registry+https://github.com/rust-lang/crates.io-index)" = "50e4785f2c3b7589a0d0c1dd60285e1188adac4006e8abd6dd578e1567027363"
 "checksum nodrop 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)" = "72ef4a56884ca558e5ddb05a1d1e7e1bfd9a68d9ed024c21704cc98872dae1bb"
 "checksum nom 5.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0b471253da97532da4b61552249c521e01e736071f71c1a4f7ebbfbf0a06aad6"
 "checksum num-derive 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0c8b15b261814f992e33760b1fca9fe8b693d8a65299f20c9901688636cfb746"
@@ -481,6 +506,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "826e7639553986605ec5979c7dd957c7895e93eabed50ab2ffa7f6128a75097c"
 "checksum vec_map 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f1bddf1187be692e79c5ffeab891132dfb0f236ed36a43c7ed39f1165ee20191"
 "checksum version_check 0.9.2 (registry+https://github.com/rust-lang/crates.io-index)" = "b5a972e5669d67ba988ce3dc826706fb0a8b01471c088cb0b6110b805cc36aed"
+"checksum void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6a02e4885ed3bc0f2de90ea6dd45ebcbb66dacffe03547fadbb0eeae2770887d"
 "checksum wasi 0.9.0+wasi-snapshot-preview1 (registry+https://github.com/rust-lang/crates.io-index)" = "cccddf32554fecc6acb585f82a32a72e28b48f8c4c1883ddfeeeaa96f7d8e519"
 "checksum winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)" = "8093091eeb260906a183e6ae1abdba2ef5ef2257a21801128899c3fc699229c6"
 "checksum winapi-i686-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"

Cargo.toml

@@ -11,6 +11,7 @@ clap = "2.33"
 crc32c = "0.4"
 flate2 = "1.0"
 libc = "0.2.71"
+nix = "0.17"
 nom = "5.1"
 num_cpus = "1.13"
 rand = "0.7"

src/file_utils.rs

@@ -1,8 +1,72 @@
-use std::fs;
+use nix::sys::stat;
+use nix::sys::stat::{FileStat, SFlag};
+use std::io;
+use std::fs::File;
+use std::os::unix::io::AsRawFd;
+
+//---------------------------------------
+
+fn check_bits(mode: u32, flag: &SFlag) -> bool {
+    (mode & flag.bits()) != 0
+}
+
+pub fn is_file_or_blk(info: FileStat) -> bool {
+    check_bits(info.st_mode, &stat::SFlag::S_IFBLK) ||
+        check_bits(info.st_mode, &stat::SFlag::S_IFREG)
+}
 
 pub fn file_exists(path: &str) -> bool {
-    return match fs::metadata(path) {
+    match stat::stat(path) {
-        Ok(_) => {true}
+        Ok(info) => {
-        Err(_) => {false}
+            return is_file_or_blk(info);
+        }
+        _ => {
+            // FIXME: assuming all errors indicate the file doesn't
+            // exist.
+            eprintln!("couldn't stat '{}'", path);
+            return false;
         }
     }
+}
+
+//---------------------------------------
+
+const BLKGETSIZE64_CODE: u8 = 0x12;
+const BLKGETSIZE64_SEQ: u8 = 114;
+ioctl_read!(ioctl_blkgetsize64, BLKGETSIZE64_CODE, BLKGETSIZE64_SEQ, u64);
+
+pub fn fail<T>(msg: &str) -> io::Result<T> {
+    let e = io::Error::new(io::ErrorKind::Other, msg);
+    Err(e)
+}
+
+fn get_device_size(path: &str) -> io::Result<u64> {
+    let _file = File::open(path)?; 
+    let fd = File::open(path).unwrap().as_raw_fd();
+    let mut cap = 0u64;
+    unsafe {
+       match ioctl_blkgetsize64(fd, &mut cap) {
+           Ok(_) => {return Ok(cap);}
+           _ => {return fail("BLKGETSIZE64 ioctl failed");}
+       }
+    }
+}
+
+pub fn file_size(path: &str) -> io::Result<u64> {
+    match stat::stat(path) {
+        Ok(info) => {
+            if check_bits(info.st_mode, &SFlag::S_IFREG) {
+                return Ok(info.st_size as u64);
+            } else if check_bits(info.st_mode, &SFlag::S_IFBLK) {
+                return get_device_size(path);
+            } else {
+                return fail("not a regular file or block device");
+            } 
+        }
+        _ => {
+            return fail("stat failed");
+        }
+    }    
+}
+
+//---------------------------------------

src/lib.rs

@@ -4,6 +4,9 @@ extern crate flate2;
 extern crate nom;
 extern crate num_cpus;
 
+#[macro_use]
+extern crate nix;
+
 #[cfg(test)]
 extern crate quickcheck;
 #[cfg(test)]

src/pack/pack.rs

@@ -19,6 +19,7 @@ use rand::prelude::*;
 use std::sync::mpsc::{sync_channel, Receiver};
 
 use crate::pack::node_encode::*;
+use crate::file_utils;
 
 const BLOCK_SIZE: u64 = 4096;
 const MAGIC: u64 = 0xa537a0aa6309ef77;
@@ -192,8 +193,8 @@ where
 }
 
 fn get_nr_blocks(path: &str) -> io::Result<u64> {
-    let metadata = std::fs::metadata(path)?;
+    let len = file_utils::file_size(path)?;
-    Ok(metadata.len() / (BLOCK_SIZE as u64))
+    Ok(len / (BLOCK_SIZE as u64))
 }
 
 fn read_blocks<R>(rdr: &mut R, b: u64, count: u64) -> io::Result<Vec<u8>>