feat: add splitPath and dirFind to sfs

src/sfs.c

@@ -636,3 +636,160 @@ static bool sfsTruncateInode(SfsInode* inode, int32 inodeNum, uint32 newSize)
         inode->blockCount--;
     }
 
+    if (neededBlocks <= sfsDirectBlocks + sfsPtrsPerBlock && inode->doubleIndirect != 0) {
+        uint8 outerBuf[sfsBlockSize];
+        if (blockRead(inode->doubleIndirect, outerBuf)) {
+            uint32* outerPtrs = (uint32*)outerBuf;
+            for (uint32 j = 0; j < sfsPtrsPerBlock; j++) {
+                if (outerPtrs[j] != 0) {
+                    freeDataBlockAbs(outerPtrs[j]);
+                    inode->blockCount--;
+                }
+            }
+        }
+        freeDataBlockAbs(inode->doubleIndirect);
+        inode->doubleIndirect = 0;
+        inode->blockCount--;
+    }
+
+    if (neededBlocks <= sfsDirectBlocks && inode->indirect != 0) {
+        freeDataBlockAbs(inode->indirect);
+        inode->indirect = 0;
+        inode->blockCount--;
+    }
+
+    inode->size = newSize;
+    inode->mtime = inode->ctime = (uint32)rtcNow();
+    return writeInodeRaw(inodeNum, inode);
+}
+
+static bool splitPath(const char* path, char* parentOut, uint64 parentCap, char* leafOut, uint64 leafCap)
+{
+    uint64 len = strlen(path);
+    while (len > 0 && path[len - 1] == '/')
+        len--;
+    if (len == 0)
+        return false;
+
+    int64 slash = -1;
+    for (int64 i = (int64)len - 1; i >= 0; i--)
+        if (path[i] == '/') {
+            slash = i;
+            break;
+        }
+
+    uint64 leafStart, leafLen;
+    if (slash < 0) {
+        parentOut[0] = 0;
+        leafStart = 0;
+        leafLen = len;
+    } else {
+        uint64 plen = (uint64)slash;
+        if (plen >= parentCap)
+            plen = parentCap - 1;
+        memcpy(parentOut, path, plen);
+        parentOut[plen] = 0;
+        leafStart = (uint64)slash + 1;
+        leafLen = len - leafStart;
+    }
+
+    if (leafLen == 0 || leafLen >= leafCap)
+        return false;
+    memcpy(leafOut, path + leafStart, leafLen);
+    leafOut[leafLen] = 0;
+    return true;
+}
+
+static int32 dirFind(int32 dirInode, const char* name, uint64 nameLen)
+{
+    SfsDirEntry entry;
+    uint64 pos = 0;
+    for (;;) {
+        int64 got = sfsReadAt(dirInode, pos, &entry, sizeof(entry));
+        if (got != (int64)sizeof(entry))
+            break;
+        if (strlen(entry.name) == nameLen && memcmp(entry.name, name, nameLen) == 0)
+            return (int32)entry.inode;
+        pos += sizeof(entry);
+    }
+    return -1;
+}
+
+static bool dirAdd(int32 dirInode, const char* name, uint64 nameLen, int32 childInode, uint32 type)
+{
+    if (nameLen == 0 || nameLen >= sfsNameMax)
+        return false;
+    if (dirFind(dirInode, name, nameLen) >= 0)
+        return false;
+
+    SfsDirEntry entry;
+    memset(&entry, 0, sizeof(entry));
+    entry.inode = (uint32)childInode;
+    entry.type = type;
+    memcpy(entry.name, name, nameLen);
+    entry.name[nameLen] = 0;
+
+    uint64 size = sfsSizeOf(dirInode);
+    return sfsWriteAt(dirInode, size, &entry, sizeof(entry)) == (int64)sizeof(entry);
+}
+
+static bool dirRemove(int32 dirInode, const char* name, uint64 nameLen)
+{
+    SfsDirEntry entry;
+    uint64 pos = 0;
+    int64 foundPos = -1;
+    for (;;) {
+        int64 got = sfsReadAt(dirInode, pos, &entry, sizeof(entry));
+        if (got != (int64)sizeof(entry))
+            break;
+        if (strlen(entry.name) == nameLen && memcmp(entry.name, name, nameLen) == 0) {
+            foundPos = (int64)pos;
+            break;
+        }
+        pos += sizeof(entry);
+    }
+    if (foundPos < 0)
+        return false;
+
+    uint64 size = sfsSizeOf(dirInode);
+    uint64 lastPos = size - sizeof(SfsDirEntry);
+    if ((uint64)foundPos != lastPos) {
+        SfsDirEntry last;
+        if (sfsReadAt(dirInode, lastPos, &last, sizeof(last)) != (int64)sizeof(last))
+            return false;
+        if (sfsWriteAt(dirInode, (uint64)foundPos, &last, sizeof(last)) != (int64)sizeof(last))
+            return false;
+    }
+
+    SfsInode inode;
+    if (!readInode(dirInode, &inode))
+        return false;
+    return sfsTruncateInode(&inode, dirInode, (uint32)lastPos);
+}
+
+static int32 createNode(const char* path, uint32 type)
+{
+    if (!isMounted)
+        return -1;
+
+    char parentBuf[256];
+    char leaf[sfsNameMax];
+    if (!splitPath(path, parentBuf, sizeof(parentBuf), leaf, sizeof(leaf)))
+        return -1;
+
+    int32 parentInode = sfsLookup(parentBuf);
+    if (parentInode < 0 || sfsTypeOf(parentInode) != sfsTypeDir)
+        return -1;
+    /* Real Unix directory-write semantics: creating a NEW entry needs
+       write permission on the PARENT directory, mirroring vfs.c's
+       vfsMkdir/resolveOpen create-branch's own equivalent tmpfs check. */
+    if (!vfsPermitted(sfsModeOf(parentInode), sfsUidOf(parentInode), sfsGidOf(parentInode),
+                       currentThreadUid(), currentThreadGid(), fsModeOwnerWrite))
+        return -1;
+    if (dirFind(parentInode, leaf, strlen(leaf)) >= 0)
+        return -1;
+
+    int32 newInode = allocInodeNum();
+    if (newInode < 0)
+        return -1;
+