[PATCH proxmox 01/26] sys: procfs: don't read from sysfs during unit tests

[Lukas Wagner <l.wagner@proxmox.com>]

When running tests in sbuild, /sys/kernel/mm/ksm/pages_sharing cannot be
read; the test fails with a 'permission denied' error. To solve this, we
move reading the file to the caller, allowing us to provide a static
string an input during the test.

Signed-off-by: Lukas Wagner <l.wagner@proxmox.com>
---
 proxmox-sys/src/linux/procfs/mod.rs | 30 +++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/proxmox-sys/src/linux/procfs/mod.rs b/proxmox-sys/src/linux/procfs/mod.rs
index 202b6a45..d399cdc3 100644
--- a/proxmox-sys/src/linux/procfs/mod.rs
+++ b/proxmox-sys/src/linux/procfs/mod.rs
@@ -434,10 +434,16 @@ pub fn read_meminfo() -> Result<ProcFsMemInfo, Error> {
     let path = "/proc/meminfo";
 
     let meminfo_str = std::fs::read_to_string(path)?;
-    parse_proc_meminfo(&meminfo_str)
+
+    let pages_sharing = match read_firstline("/sys/kernel/mm/ksm/pages_sharing") {
+        Ok(p) => Some(p),
+        Err(err) if err.kind() == std::io::ErrorKind::NotFound => None,
+        Err(err) => bail!("unable to get KSM pages_sharing - {err}"),
+    };
+    parse_proc_meminfo(&meminfo_str, pages_sharing.as_deref())
 }
 
-fn parse_proc_meminfo(text: &str) -> Result<ProcFsMemInfo, Error> {
+fn parse_proc_meminfo(text: &str, pages_sharing: Option<&str>) -> Result<ProcFsMemInfo, Error> {
     let mut meminfo = ProcFsMemInfo {
         memtotal: 0,
         memfree: 0,
@@ -471,10 +477,9 @@ fn parse_proc_meminfo(text: &str) -> Result<ProcFsMemInfo, Error> {
 
     meminfo.swapused = meminfo.swaptotal - meminfo.swapfree;
 
-    meminfo.memshared = match read_firstline("/sys/kernel/mm/ksm/pages_sharing") {
-        Ok(spages_line) => spages_line.trim_end().parse::<u64>()? * 4096,
-        Err(err) if err.kind() == std::io::ErrorKind::NotFound => 0,
-        Err(err) => bail!("unable to get KSM pages_sharing - {err}"),
+    meminfo.memshared = match pages_sharing {
+        Some(pages_sharing) => pages_sharing.trim_end().parse::<u64>()? * 4096,
+        None => 0,
     };
 
     Ok(meminfo)
@@ -482,8 +487,7 @@ fn parse_proc_meminfo(text: &str) -> Result<ProcFsMemInfo, Error> {
 
 #[test]
 fn test_read_proc_meminfo() {
-    let meminfo = parse_proc_meminfo(
-        "MemTotal:       32752584 kB
+    let proc_meminfo = "MemTotal:       32752584 kB
 MemFree:         2106048 kB
 MemAvailable:   13301592 kB
 Buffers:               0 kB
@@ -538,9 +542,14 @@ Hugetlb:               0 kB
 DirectMap4k:      237284 kB
 DirectMap2M:    13281280 kB
 DirectMap1G:    22020096 kB
+";
+
+    let pages_sharing = Some(
+        "2
 ",
-    )
-    .expect("successful parsed a sample /proc/meminfo entry");
+    );
+    let meminfo = parse_proc_meminfo(proc_meminfo, pages_sharing)
+        .expect("successful parsed a sample /proc/meminfo entry");
 
     assert_eq!(meminfo.memtotal, 33538646016);
     assert_eq!(meminfo.memused, 19917815808);
@@ -549,6 +558,7 @@ DirectMap1G:    22020096 kB
     assert_eq!(meminfo.swapfree, 2048);
     assert_eq!(meminfo.swaptotal, 3072);
     assert_eq!(meminfo.swapused, 1024);
+    assert_eq!(meminfo.memshared, 8192);
 }
 
 #[derive(Clone, Debug)]
-- 
2.47.3