[demrom]

Running an alias with its output redirected can abort in ios_system with Assertion failed: (endFile <= maxPointer). maxPointer is set from the original command string. Alias expansion builds the expanded command in a new allocation and frees the original, but the redirection parser still checks file name ends against the old bound. The assert fires only when the new string lands above the end of the old one, so the outcome depends on where malloc puts it.

This change recomputes maxPointer from the expanded command before redirections are parsed. The same line covers a command name taken from an environment variable ($NAME), which replaces the string the same way; the test does not exercise that path.

tests/alias-redirection.m aliases a registered command with two arguments and runs it with stdout and stderr redirected to files. The alias is padded with 2048 spaces: without the padding the test passed even before the fix. With the command in tests/README.md (Xcode 27.1, arm64 Release, Simulator SDK 27.1, iOS 15 deployment target) and the added line reverted, the test aborts on the assert in three runs out of three. With this change, all three runs return status 7, and each file holds exactly the expected line.