[pbs-devel] [PATCH backup] inspect: don't panic when writing to a broken pipe

[Maximiliano Sandoval]

println [panics] if writing to stdout fails. This can be reproduced by
calling

```
proxmox-backup-debug inspect file {FIXED_INDEX_FILE} | head
```

for example.

[panics] https://doc.rust-lang.org/std/macro.println.html#panics

Signed-off-by: Maximiliano Sandoval <m.sandoval at proxmox.com>
---

This raises the question of where else the same change should be done and
whether it is worth it. Imho wanting to see the first 10 or so chunks of an
index file for debugging purposes should come often enough that this should be
fine here.

 src/bin/proxmox_backup_debug/inspect.rs | 70 ++++++++++++++++---------
 1 file changed, 44 insertions(+), 26 deletions(-)

diff --git a/src/bin/proxmox_backup_debug/inspect.rs b/src/bin/proxmox_backup_debug/inspect.rs
index 321080be3..c75871da9 100644
--- a/src/bin/proxmox_backup_debug/inspect.rs
+++ b/src/bin/proxmox_backup_debug/inspect.rs
@@ -203,16 +203,21 @@ fn inspect_chunk(
     };
 
     if output_format == "text" {
-        println!("CRC: {}", val["crc"]);
-        println!("encryption: {}", val["encryption"]);
-        println!("is-compressed: {}", val["is-compressed"]);
-        println!("size: {}", val["size"]);
-        if let Some(refs) = val["referenced-by"].as_array() {
-            println!("referenced by:");
-            for reference in refs {
-                println!("  {}", reference);
+        fn print_to_stdout(val: Value) -> std::io::Result<()> {
+            let mut stdout = std::io::stdout();
+            writeln!(&mut stdout, "CRC: {}", val["crc"])?;
+            writeln!(&mut stdout, "encryption: {}", val["encryption"])?;
+            writeln!(&mut stdout, "is-compressed: {}", val["is-compressed"])?;
+            writeln!(&mut stdout, "size: {}", val["size"])?;
+            if let Some(refs) = val["referenced-by"].as_array() {
+                writeln!(&mut stdout, "referenced by:")?;
+                for reference in refs {
+                    writeln!(&mut stdout, "  {}", reference)?;
+                }
             }
+            Ok(())
         }
+        let _ = print_to_stdout(val);
     } else {
         format_and_print_result(&val, &output_format);
     }
@@ -311,19 +316,25 @@ fn inspect_file(
     };
 
     if output_format == "text" {
-        println!("size: {}", val["size"]);
-        if let Some(encryption) = val["encryption"].as_str() {
-            println!("encryption: {}", encryption);
-        }
-        if let Some(ctime) = val["ctime"].as_str() {
-            println!("creation time: {}", ctime);
-        }
-        if let Some(chunks) = val["chunk-digests"].as_array() {
-            println!("chunks:");
-            for chunk in chunks {
-                println!("  {}", chunk);
+        fn print_to_stdout(val: Value) -> std::io::Result<()> {
+            let mut stdout = std::io::stdout();
+            writeln!(&mut stdout, "size: {}", val["size"])?;
+            if let Some(encryption) = val["encryption"].as_str() {
+                writeln!(&mut stdout, "encryption: {}", encryption)?;
             }
+            if let Some(ctime) = val["ctime"].as_str() {
+                writeln!(&mut stdout, "creation time: {}", ctime)?;
+            }
+            if let Some(chunks) = val["chunk-digests"].as_array() {
+                writeln!(&mut stdout, "chunks:")?;
+                for chunk in chunks {
+                    writeln!(&mut stdout, "  {}", chunk)?;
+                }
+            }
+            Ok(())
         }
+
+        let _ = print_to_stdout(val);
     } else {
         format_and_print_result(&val, &output_format);
     }
@@ -458,14 +469,21 @@ fn inspect_device(device: String, param: Value) -> Result<(), Error> {
     std::fs::remove_dir(std::path::Path::new(&tmp_mount_path))?;
 
     if output_format == "text" {
-        println!("Device contains {ds_count} stores");
-        println!("---------------");
-        for s in stores {
-            println!(
-                "Datastore at {} | VM: {}, CT: {}, HOST: {}, NS: {}",
-                s["path"], s["vm-count"], s["ct-count"], s["host-count"], s["ns-count"]
-            );
+        fn print_to_stdout(ds_count: i32, stores: &[Value]) -> std::io::Result<()> {
+            let mut stdout = std::io::stdout();
+
+            writeln!(&mut stdout, "Device contains {ds_count} stores")?;
+            writeln!(&mut stdout, "---------------")?;
+            for s in stores {
+                writeln!(
+                    &mut stdout,
+                    "Datastore at {} | VM: {}, CT: {}, HOST: {}, NS: {}",
+                    s["path"], s["vm-count"], s["ct-count"], s["host-count"], s["ns-count"]
+                )?;
+            }
+            Ok(())
         }
+        let _ = print_to_stdout(ds_count, &stores);
     } else {
         format_and_print_result(
             &json!({"store_count": stores.len(), "stores": stores}),
-- 
2.39.5