Abstract getting unique status result into a single method

src/cachedev.rs

@@ -14,9 +14,9 @@ use crate::{
     lineardev::{LinearDev, LinearDevTargetParams},
     result::{DmError, DmResult, ErrorEnum},
     shared::{
-        device_create, device_exists, device_match, get_status, get_status_line_fields,
-        make_unexpected_value_error, parse_device, parse_value, DmDevice, TargetLine, TargetParams,
-        TargetTable, TargetTypeBuf,
+        device_create, device_exists, device_match, get_status, get_status_line,
+        get_status_line_fields, make_unexpected_value_error, parse_device, parse_value, DmDevice,
+        TargetLine, TargetParams, TargetTable, TargetTypeBuf,
     },
     units::{DataBlocks, MetaBlocks, Sectors},
 };
@@ -369,6 +369,8 @@ impl FromStr for CacheDevStatus {
     // Note: This method is not entirely complete. In particular, *_args values
     // may require more or better checking or processing.
     fn from_str(status_line: &str) -> DmResult<CacheDevStatus> {
+        let status_line = get_status_line(status_line, &CACHE_TARGET_NAME)?;
+
         if status_line.starts_with("Error") {
             return Ok(CacheDevStatus::Error);
         }

src/shared.rs

@@ -226,6 +226,27 @@ where
     })
 }
 
+/// Obtain a status line from a line containing the target type as its first
+/// entry. Return an error if the line does not have the expected target type.
+/// Precondition: The line's first entry is the target type, followed by a
+/// space, followed by the actual status values.
+pub fn get_status_line<'a, 'b>(
+    status_line: &'a str,
+    expected_target_type: &'b str,
+) -> DmResult<&'a str> {
+    let target_status_pair: Vec<&str> = status_line.splitn(2, ' ').collect();
+    let target_type = target_status_pair[0];
+    if target_type != expected_target_type {
+        let err_msg = format!(
+            "Expected a \"{}\" target entry but found target type \"{}\" in \"{}\"",
+            expected_target_type, target_type, status_line
+        );
+        return Err(DmError::Dm(ErrorEnum::Invalid, err_msg));
+    }
+
+    Ok(target_status_pair[1])
+}
+
 /// Get fields for a single status line.
 /// Return an error if an insufficient number of fields are obtained.
 pub fn get_status_line_fields<'a>(
@@ -260,11 +281,10 @@ pub fn get_status(status_lines: &[(u64, u64, String, String)]) -> DmResult<Strin
             ),
         ));
     }
-    Ok(status_lines
+    let line = status_lines
         .first()
-        .expect("if length != 1, already returned")
-        .3
-        .to_owned())
+        .expect("if length != 1, already returned");
+    Ok(format!("{} {}", line.2, line.3))
 }
 
 /// Construct an error when parsing yields an unexpected value.

src/thindev.rs

@@ -8,8 +8,9 @@ use crate::{
     core::{DevId, Device, DeviceInfo, DmCookie, DmFlags, DmName, DmOptions, DmUuid, DM},
     result::{DmError, DmResult, ErrorEnum},
     shared::{
-        device_create, device_exists, device_match, get_status, get_status_line_fields, message,
-        parse_device, parse_value, DmDevice, TargetLine, TargetParams, TargetTable, TargetTypeBuf,
+        device_create, device_exists, device_match, get_status, get_status_line,
+        get_status_line_fields, message, parse_device, parse_value, DmDevice, TargetLine,
+        TargetParams, TargetTable, TargetTypeBuf,
     },
     thindevid::ThinDevId,
     thinpooldev::ThinPoolDev,
@@ -219,6 +220,8 @@ impl FromStr for ThinStatus {
     type Err = DmError;
 
     fn from_str(status_line: &str) -> DmResult<ThinStatus> {
+        let status_line = get_status_line(status_line, &THIN_TARGET_NAME)?;
+
         if status_line.starts_with("Error") {
             return Ok(ThinStatus::Error);
         }

src/thinpooldev.rs

@@ -9,9 +9,9 @@ use crate::{
     lineardev::{LinearDev, LinearDevTargetParams},
     result::{DmError, DmResult, ErrorEnum},
     shared::{
-        device_create, device_exists, device_match, get_status, get_status_line_fields,
-        make_unexpected_value_error, parse_device, parse_value, DmDevice, TargetLine, TargetParams,
-        TargetTable, TargetTypeBuf,
+        device_create, device_exists, device_match, get_status, get_status_line,
+        get_status_line_fields, make_unexpected_value_error, parse_device, parse_value, DmDevice,
+        TargetLine, TargetParams, TargetTable, TargetTypeBuf,
     },
     units::{DataBlocks, MetaBlocks, Sectors},
 };
@@ -337,6 +337,8 @@ impl FromStr for ThinPoolStatus {
     type Err = DmError;
 
     fn from_str(status_line: &str) -> DmResult<ThinPoolStatus> {
+        let status_line = get_status_line(status_line, &THINPOOL_TARGET_NAME)?;
+
         if status_line.starts_with("Error") {
             return Ok(ThinPoolStatus::Error);
         }