diff --git a/library/std/src/sys/dbg.rs b/library/std/src/sys/dbg.rs index 383ed84cfa2..7266a739e78 100644 --- a/library/std/src/sys/dbg.rs +++ b/library/std/src/sys/dbg.rs @@ -105,84 +105,7 @@ mod os { } } -#[cfg(target_os = "linux")] -mod os { - use super::DebuggerPresence; - use crate::fs::File; - use crate::io::Read; - - pub(super) fn is_debugger_present() -> Option { - // This function is crafted with the following goals: - // * Memory efficiency: It avoids crashing the panicking process due to - // out-of-memory (OOM) conditions by not using large heap buffers or - // allocating significant stack space, which could lead to stack overflow. - // * Minimal binary size: The function uses a minimal set of facilities - // from the standard library to avoid increasing the resulting binary size. - // - // To achieve these goals, the function does not use `[std::io::BufReader]` - // and instead reads the file byte by byte using a sliding window approach. - // It's important to note that the "/proc/self/status" pseudo-file is synthesized - // by the Virtual File System (VFS), meaning it is not read from a slow or - // non-volatile storage medium so buffering might not be as beneficial because - // all data is read from memory, though this approach does incur a syscall for - // each byte read. - // - // We cannot make assumptions about the file size or the position of the - // target prefix ("TracerPid:"), so the function does not use - // `[std::fs::read_to_string]` thus not employing UTF-8 to ASCII checking, - // conversion, or parsing as we're looking for an ASCII prefix. - // - // These condiderations make the function deviate from the familiar concise pattern - // of searching for a string in a text file. - - fn read_byte(file: &mut File) -> Option { - let mut buffer = [0]; - file.read_exact(&mut buffer).ok()?; - Some(buffer[0]) - } - - // The ASCII prefix of the datum we're interested in. - const TRACER_PID: &[u8] = b"TracerPid:\t"; - - let mut file = File::open("/proc/self/status").ok()?; - let mut matched = 0; - - // Look for the `TRACER_PID` prefix. - while let Some(byte) = read_byte(&mut file) { - if byte == TRACER_PID[matched] { - matched += 1; - if matched == TRACER_PID.len() { - break; - } - } else { - matched = 0; - } - } - - // Was the prefix found? - if matched != TRACER_PID.len() { - return None; - } - - // It was; get the ASCII representation of the first digit - // of the PID. That is enough to see if there is a debugger - // attached as the kernel does not pad the PID on the left - // with the leading zeroes. - let byte = read_byte(&mut file)?; - if byte.is_ascii_digit() && byte != b'0' { - Some(DebuggerPresence::Detected) - } else { - Some(DebuggerPresence::NotDetected) - } - } -} - -#[cfg(not(any( - target_os = "windows", - target_vendor = "apple", - target_os = "freebsd", - target_os = "linux" -)))] +#[cfg(not(any(target_os = "windows", target_vendor = "apple", target_os = "freebsd")))] mod os { pub(super) fn is_debugger_present() -> Option { None