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Better mount detection #289

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Merged
wonderwhy-er merged 1 commit into from
Dec 10, 2025
Merged

Better mount detection #289

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47 changes: 43 additions & 4 deletions src/utils/system-info.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -197,19 +197,58 @@ function discoverContainerMounts(isContainer: boolean): DockerMount[] {
const mountsContent = fs.readFileSync('/proc/mounts', 'utf8');
const mountLines = mountsContent.split('\n');

// System filesystem types that are never user mounts
const systemFsTypes = new Set([
'overlay', 'tmpfs', 'proc', 'sysfs', 'devpts', 'cgroup', 'cgroup2',
'mqueue', 'debugfs', 'securityfs', 'pstore', 'configfs', 'fusectl',
'hugetlbfs', 'autofs', 'devtmpfs', 'bpf', 'tracefs', 'shm'
]);

// Filesystem types that indicate host mounts
const hostMountFsTypes = new Set(['fakeowner', '9p', 'virtiofs', 'fuse.sshfs']);

for (const line of mountLines) {
const parts = line.split(' ');
if (parts.length >= 4) {
const device = parts[0];
const mountPoint = parts[1];
const fsType = parts[2];
const options = parts[3];

// Look for user mounts (skip system mounts)
if (mountPoint.startsWith('/mnt/') ||
// Skip system mount points
const isSystemMountPoint =
mountPoint === '/' ||
mountPoint.startsWith('/dev') ||
mountPoint.startsWith('/sys') ||
mountPoint.startsWith('/proc') ||
mountPoint.startsWith('/run') ||
mountPoint.startsWith('/sbin') ||
mountPoint === '/etc/resolv.conf' ||
mountPoint === '/etc/hostname' ||
mountPoint === '/etc/hosts';

if (isSystemMountPoint) {
continue;
}

// Detect user mounts by:
// 1. Known host-mount filesystem types (fakeowner, 9p, virtiofs)
// 2. Device from /run/host_mark/ (docker-mcp-gateway pattern)
// 3. Non-system filesystem type with user-like mount point
const isHostMountFs = hostMountFsTypes.has(fsType);
const isHostMarkDevice = device.startsWith('/run/host_mark/');
const isNonSystemFs = !systemFsTypes.has(fsType);
const isUserLikePath = mountPoint.startsWith('/mnt/') ||
mountPoint.startsWith('/workspace') ||
mountPoint.startsWith('/data/') ||
(mountPoint.startsWith('/home/') && !mountPoint.startsWith('/home/root'))) {

mountPoint.startsWith('/home/') ||
mountPoint.startsWith('/Users/') ||
mountPoint.startsWith('/app/') ||
mountPoint.startsWith('/project/') ||
mountPoint.startsWith('/src/') ||
mountPoint.startsWith('/code/');

if (isHostMountFs || isHostMarkDevice || (isNonSystemFs && isUserLikePath)) {
const isReadOnly = options.includes('ro');
Comment on lines +234 to 252

@coderabbitai coderabbitai Bot Dec 9, 2025

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⚠️ Potential issue | 🟡 Minor

Tighten read-only detection and consider normalizing user-like path heuristics

The combined condition

if (isHostMountFs || isHostMarkDevice || (isNonSystemFs && isUserLikePath)) {

is a solid improvement and should catch many realistic host mounts.

One minor correctness issue:

const isReadOnly = options.includes('ro');

can misclassify mounts such as rw,errors=remount-ro as read-only because ro appears as a substring. It’s safer to parse mount options by token:

- const isReadOnly = options.includes('ro');
+ const mountOptions = options.split(',');
+ const isReadOnly = mountOptions.includes('ro');

This avoids false positives while preserving behavior for true ro mounts.

As an optional polish, you might also consider whether isUserLikePath should distinguish /workspace from /workspace-* (currently startsWith('/workspace') matches both) and whether any additional project-specific prefixes should be centralized/configurable.

🤖 Prompt for AI Agents 
In src/utils/system-info.ts around lines 234 to 252, the read-only detection
uses options.includes('ro') which can falsely match substrings like
"errors=remount-ro"; instead split or tokenize the mount options by comma (and
trim each token) and check for an exact 'ro' token (e.g.,
options.split(',').map(t=>t.trim()).includes('ro')). Update the isReadOnly
assignment to use this tokenized check. Optionally, when updating nearby code,
consider tightening the isUserLikePath heuristics (e.g., match '/workspace'
exactly or use a configurable prefix list) but the immediate fix is to replace
the substring check with a comma-token exact-match check for 'ro'.


mounts.push({
Expand Down