aya: refactor handling of /proc/$pid/maps

This commit refactors the handling of /proc/$pid/maps since the
collection previously assumed that all entries here could be
representeted in a HashMap. Those with a path component are stored
in a HashSet for fast lookup via library name. All other entries
are cached in a Vec to allow for filtering based on offsets, required
for supporting USDT probes.

Signed-off-by: Dave Tucker <dave@dtucker.co.uk>

aya/src/programs/uprobe.rs

@@ -3,13 +3,16 @@ use libc::pid_t;
 use object::{Object, ObjectSection, ObjectSymbol};
 use std::{
     borrow::Cow,
+    collections::HashSet,
     error::Error,
     ffi::CStr,
     fs,
     io::{self, BufRead, Cursor, Read},
     mem,
+    num::ParseIntError,
     os::{fd::AsFd as _, raw::c_char},
     path::{Path, PathBuf},
+    str::FromStr,
     sync::Arc,
 };
 use thiserror::Error;
@@ -136,12 +139,17 @@ fn resolve_attach_path<T: AsRef<Path>>(
     };
     let target_str = target.to_str().ok_or_else(invalid_target)?;
     pid.and_then(|pid| {
-        find_lib_in_proc_maps(pid, target_str)
+        ProcMap::new(pid)
-            .map_err(|io_error| UProbeError::FileError {
+            .map_err(|source| UProbeError::ProcMap { pid, source })
-                filename: format!("/proc/{pid}/maps"),
+            .and_then(|proc_map_libs| {
-                io_error,
+                proc_map_libs
+                    .find_library_path_by_name(target_str)
+                    .map_err(|io_error| UProbeError::FileError {
+                        filename: format!("/proc/{pid}/maps"),
+                        io_error,
+                    })
+                    .map(|v| v.map(|v| Cow::Owned(v.to_owned())))
             })
-            .map(|v| v.map(Cow::Owned))
             .transpose()
     })
     .or_else(|| target.is_absolute().then(|| Ok(Cow::Borrowed(target_str))))
@@ -216,7 +224,7 @@ pub enum UProbeError {
     /// There was an error parsing `/etc/ld.so.cache`.
     #[error("error reading `{}` file", LD_SO_CACHE_FILE)]
     InvalidLdSoCache {
-        /// the original [`io::Error`]
+        /// the original [`io::Error`].
         #[source]
         io_error: Arc<io::Error>,
     },
@@ -224,16 +232,16 @@ pub enum UProbeError {
     /// The target program could not be found.
     #[error("could not resolve uprobe target `{path}`")]
     InvalidTarget {
-        /// path to target
+        /// path to target.
         path: PathBuf,
     },
 
     /// There was an error resolving the target symbol.
     #[error("error resolving symbol")]
     SymbolError {
-        /// symbol name
+        /// symbol name.
         symbol: String,
-        /// the original error
+        /// the original error.
         #[source]
         error: Box<dyn Error + Send + Sync>,
     },
@@ -241,49 +249,23 @@ pub enum UProbeError {
     /// There was an error accessing `filename`.
     #[error("`{filename}`")]
     FileError {
-        /// The file name
+        /// The file name.
         filename: String,
-        /// The [`io::Error`] returned from the file operation
+        /// The [`io::Error`] returned from the file operation.
         #[source]
         io_error: io::Error,
     },
-}
-
-fn proc_maps_libs(pid: pid_t) -> Result<Vec<(String, String)>, io::Error> {
-    let maps_file = format!("/proc/{pid}/maps");
-    let data = fs::read_to_string(maps_file)?;
-
-    Ok(data
-        .lines()
-        .filter_map(|line| {
-            let line = line.split_whitespace().last()?;
-            if line.starts_with('/') {
-                let path = PathBuf::from(line);
-                let key = path.file_name().unwrap().to_string_lossy().into_owned();
-                Some((key, path.to_string_lossy().to_string()))
-            } else {
-                None
-            }
-        })
-        .collect())
-}
-
-fn find_lib_in_proc_maps(pid: pid_t, lib: &str) -> Result<Option<String>, io::Error> {
-    let libs = proc_maps_libs(pid)?;
-
-    let ret = if lib.contains(".so") {
-        libs.into_iter().find(|(k, _)| k.as_str().starts_with(lib))
-    } else {
-        libs.into_iter().find(|(k, _)| {
-            k.strip_prefix(lib)
-                .map(|k| k.starts_with(".so") || k.starts_with('-'))
-                .unwrap_or_default()
-        })
-    };
 
-    Ok(ret.map(|(_, v)| v))
+    /// There was en error fetching the memory map for `pid`.
+    #[error("error fetching libs for {pid}")]
+    ProcMap {
+        /// The pid.
+        pid: i32,
+        /// The [`ProcMapError`] that caused the error.
+        #[source]
+        source: ProcMapError,
+    },
 }
-
 #[derive(Debug)]
 pub(crate) struct CacheEntry {
     key: String,
@@ -450,3 +432,277 @@ fn resolve_symbol(path: &str, symbol: &str) -> Result<u64, ResolveSymbolError> {
         Ok(sym.address() - section.address() + offset)
     }
 }
+
+/// Error reading from /proc/pid/maps.
+#[derive(Debug, Error)]
+pub enum ProcMapError {
+    /// Unable to read /proc/pid/maps.
+    #[error(transparent)]
+    Read(io::Error),
+
+    /// Error parsing an integer.
+    #[error(transparent)]
+    ParseInt(#[from] ParseIntError),
+
+    /// Error parsing a line of /proc/pid/maps.
+    #[error("proc map entry parse error")]
+    Parse,
+}
+
+/// The memory maps of a process.
+///
+/// This is read from /proc/`pid`/maps.
+///
+/// The information here may be used to resolve addresses to paths.
+struct ProcMap {
+    // This is going to be used by USDT probes to resolve virtual addresses to
+    // library paths.
+    _entries: Vec<ProcMapEntry>,
+    libraries: HashSet<PathBuf>,
+}
+
+impl ProcMap {
+    /// Create a new [`ProcMap`] from a given pid.
+    fn new(pid: pid_t) -> Result<Self, ProcMapError> {
+        let maps_file = format!("/proc/{}/maps", pid);
+        let data = fs::read_to_string(maps_file).map_err(ProcMapError::Read)?;
+        Self::from_str(&data)
+    }
+
+    // Find the full path of a library by its name.
+    //
+    // This isn't part of the public API since it's really only useful for
+    // attaching uprobes.
+    fn find_library_path_by_name(&self, lib: &str) -> Result<Option<&str>, io::Error> {
+        let ret = if lib.contains(".so") {
+            self.libraries.iter().find(|p| {
+                p.file_name()
+                    .and_then(|s| s.to_str())
+                    .map(|s| s.starts_with(lib))
+                    .unwrap_or_default()
+            })
+        } else {
+            self.libraries.iter().find(|p| {
+                p.file_name()
+                    .and_then(|s| s.to_str())
+                    .map(|s| {
+                        s.strip_prefix(lib)
+                            .map(|k| k.starts_with(".so") || k.starts_with('-'))
+                            .unwrap_or_default()
+                    })
+                    .unwrap_or_default()
+            })
+        };
+
+        Ok(ret.map(|p| {
+            p.as_os_str()
+                .to_str()
+                .expect("library path should be valid UTF-8")
+        }))
+    }
+}
+
+impl FromStr for ProcMap {
+    type Err = ProcMapError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let mut entries = vec![];
+        let mut libraries = HashSet::new();
+        for line in s.lines() {
+            let entry = ProcMapEntry::from_str(line)?;
+            if let Some(path) = &entry.path {
+                let library_path = PathBuf::from(path);
+                libraries.insert(library_path);
+            }
+            entries.push(entry);
+        }
+        Ok(ProcMap {
+            _entries: entries,
+            libraries,
+        })
+    }
+}
+
+/// A entry that has been parsed from /proc/`pid`/maps.
+///
+/// This contains information about a mapped portion of memory
+/// for the process, ranging from address to address_end.
+#[derive(Debug)]
+struct ProcMapEntry {
+    _address: u64,
+    _address_end: u64,
+    _perms: String,
+    _offset: u64,
+    _dev: String,
+    _inode: u32,
+    path: Option<String>,
+}
+
+impl FromStr for ProcMapEntry {
+    type Err = ProcMapError;
+
+    fn from_str(line: &str) -> Result<Self, Self::Err> {
+        let mut parts = line.split_whitespace();
+        let mut next = || parts.next().ok_or(ProcMapError::Parse);
+        let (address, address_end) = next()?
+            .split_once('-')
+            .ok_or(ProcMapError::Parse)
+            .and_then(|(start, end)| {
+                let start = u64::from_str_radix(start, 16)?;
+                let end = u64::from_str_radix(end, 16)?;
+                Ok((start, end))
+            })?;
+        let perms = next()?;
+        let offset = u64::from_str_radix(next()?, 16)?;
+        let dev = next()?;
+        let inode = next()?.parse()?;
+        let path = parts
+            .next()
+            .and_then(|s| s.starts_with('/').then(|| s.to_string()));
+        Ok(ProcMapEntry {
+            _address: address,
+            _address_end: address_end,
+            _perms: perms.to_string(),
+            _offset: offset,
+            _dev: dev.to_string(),
+            _inode: inode,
+            path,
+        })
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use assert_matches::assert_matches;
+
+    #[test]
+    fn test_parse_proc_map_entry_shared_lib() {
+        let s = "7ffd6fbea000-7ffd6fbec000 r-xp 00000000 00:00 0                          [vdso]";
+        let proc_map = ProcMapEntry::from_str(s).unwrap();
+        assert_eq!(proc_map._address, 0x7ffd6fbea000);
+        assert_eq!(proc_map._address_end, 0x7ffd6fbec000);
+        assert_eq!(proc_map._perms, "r-xp");
+        assert_eq!(proc_map._offset, 0x0);
+        assert_eq!(proc_map._dev, "00:00");
+        assert_eq!(proc_map._inode, 0);
+        assert_eq!(proc_map.path, None);
+    }
+
+    #[test]
+    fn test_parse_proc_map_entry_absolute_path() {
+        let s = "7f1bca83a000-7f1bca83c000 rw-p 00036000 fd:01 2895508                    /usr/lib64/ld-linux-x86-64.so.2";
+        let proc_map = ProcMapEntry::from_str(s).unwrap();
+        assert_eq!(proc_map._address, 0x7f1bca83a000);
+        assert_eq!(proc_map._address_end, 0x7f1bca83c000);
+        assert_eq!(proc_map._perms, "rw-p");
+        assert_eq!(proc_map._offset, 0x00036000);
+        assert_eq!(proc_map._dev, "fd:01");
+        assert_eq!(proc_map._inode, 2895508);
+        assert_eq!(
+            proc_map.path,
+            Some("/usr/lib64/ld-linux-x86-64.so.2".to_string())
+        );
+    }
+
+    #[test]
+    fn test_parse_proc_map_entry_all_zeros() {
+        let s = "7f1bca5f9000-7f1bca601000 rw-p 00000000 00:00 0";
+        let proc_map = ProcMapEntry::from_str(s).unwrap();
+        assert_eq!(proc_map._address, 0x7f1bca5f9000);
+        assert_eq!(proc_map._address_end, 0x7f1bca601000);
+        assert_eq!(proc_map._perms, "rw-p");
+        assert_eq!(proc_map._offset, 0x0);
+        assert_eq!(proc_map._dev, "00:00");
+        assert_eq!(proc_map._inode, 0);
+        assert_eq!(proc_map.path, None);
+    }
+
+    #[test]
+    fn test_parse_proc_map_entry_parse_errors() {
+        assert_matches!(
+            ProcMapEntry::from_str(
+                "zzzz-7ffd6fbea000 r-xp 00000000 00:00 0                          [vdso]"
+            ),
+            Err(ProcMapError::ParseInt(_))
+        );
+
+        assert_matches!(
+            ProcMapEntry::from_str(
+                "zzzz-7ffd6fbea000 r-xp 00000000 00:00 0                          [vdso]"
+            ),
+            Err(ProcMapError::ParseInt(_))
+        );
+
+        assert_matches!(
+            ProcMapEntry::from_str(
+                "7f1bca5f9000-7f1bca601000 r-xp zzzz 00:00 0                          [vdso]"
+            ),
+            Err(ProcMapError::ParseInt(_))
+        );
+
+        assert_matches!(
+            ProcMapEntry::from_str(
+                "7f1bca5f9000-7f1bca601000 r-xp 00000000 00:00 zzzz                          [vdso]"
+            ),
+            Err(ProcMapError::ParseInt(_))
+        );
+
+        assert_matches!(
+            ProcMapEntry::from_str(
+                "7f1bca5f90007ffd6fbea000 r-xp 00000000 00:00 0                          [vdso]"
+            ),
+            Err(ProcMapError::Parse)
+        );
+
+        assert_matches!(
+            ProcMapEntry::from_str("7f1bca5f9000-7f1bca601000 r-xp 00000000"),
+            Err(ProcMapError::Parse)
+        );
+    }
+
+    #[test]
+    fn test_proc_map_find_lib_by_name() {
+        let proc_map_libs = ProcMap::from_str(
+            r#"7fc4a9800000-7fc4a98ad000 r--p 00000000 00:24 18147308                   /usr/lib64/libcrypto.so.3.0.9"# 
+        ).unwrap();
+
+        assert_eq!(
+            proc_map_libs
+                .find_library_path_by_name("libcrypto.so.3.0.9")
+                .unwrap(),
+            Some("/usr/lib64/libcrypto.so.3.0.9")
+        );
+    }
+
+    #[test]
+    fn test_proc_map_find_lib_by_partial_name() {
+        let proc_map_libs = ProcMap::from_str(
+            r#"7fc4a9800000-7fc4a98ad000 r--p 00000000 00:24 18147308                   /usr/lib64/libcrypto.so.3.0.9"# 
+        ).unwrap();
+
+        assert_eq!(
+            proc_map_libs
+                .find_library_path_by_name("libcrypto")
+                .unwrap(),
+            Some("/usr/lib64/libcrypto.so.3.0.9")
+        );
+    }
+
+    #[test]
+    fn test_proc_map_with_multiple_lib_entries() {
+        let proc_map_libs = ProcMap::from_str(
+            r#"7f372868000-7f3722869000 r--p 00000000 00:24 18097875                   /usr/lib64/ld-linux-x86-64.so.2
+            7f3722869000-7f372288f000 r-xp 00001000 00:24 18097875                   /usr/lib64/ld-linux-x86-64.so.2
+            7f372288f000-7f3722899000 r--p 00027000 00:24 18097875                   /usr/lib64/ld-linux-x86-64.so.2
+            7f3722899000-7f372289b000 r--p 00030000 00:24 18097875                   /usr/lib64/ld-linux-x86-64.so.2
+            7f372289b000-7f372289d000 rw-p 00032000 00:24 18097875                   /usr/lib64/ld-linux-x86-64.so.2"#)
+            .unwrap();
+        assert_eq!(
+            proc_map_libs
+                .find_library_path_by_name("ld-linux-x86-64.so.2")
+                .unwrap(),
+            Some("/usr/lib64/ld-linux-x86-64.so.2")
+        );
+    }
+}

xtask/public-api/aya.txt

@@ -4319,6 +4319,43 @@ pub fn aya::programs::trace_point::TracePointLinkId::borrow_mut(&mut self) -> &m
 impl<T> core::convert::From<T> for aya::programs::trace_point::TracePointLinkId
 pub fn aya::programs::trace_point::TracePointLinkId::from(t: T) -> T
 pub mod aya::programs::uprobe
+pub enum aya::programs::uprobe::ProcMapError
+pub aya::programs::uprobe::ProcMapError::Parse
+pub aya::programs::uprobe::ProcMapError::ParseInt(core::num::error::ParseIntError)
+pub aya::programs::uprobe::ProcMapError::Read(std::io::error::Error)
+impl core::convert::From<core::num::error::ParseIntError> for aya::programs::uprobe::ProcMapError
+pub fn aya::programs::uprobe::ProcMapError::from(source: core::num::error::ParseIntError) -> Self
+impl core::error::Error for aya::programs::uprobe::ProcMapError
+pub fn aya::programs::uprobe::ProcMapError::source(&self) -> core::option::Option<&(dyn core::error::Error + 'static)>
+impl core::fmt::Display for aya::programs::uprobe::ProcMapError
+pub fn aya::programs::uprobe::ProcMapError::fmt(&self, __formatter: &mut core::fmt::Formatter<'_>) -> core::fmt::Result
+impl core::fmt::Debug for aya::programs::uprobe::ProcMapError
+pub fn aya::programs::uprobe::ProcMapError::fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result
+impl core::marker::Send for aya::programs::uprobe::ProcMapError
+impl core::marker::Sync for aya::programs::uprobe::ProcMapError
+impl core::marker::Unpin for aya::programs::uprobe::ProcMapError
+impl !core::panic::unwind_safe::RefUnwindSafe for aya::programs::uprobe::ProcMapError
+impl !core::panic::unwind_safe::UnwindSafe for aya::programs::uprobe::ProcMapError
+impl<E> core::any::Provider for aya::programs::uprobe::ProcMapError where E: core::error::Error + core::marker::Sized
+pub fn aya::programs::uprobe::ProcMapError::provide<'a>(&'a self, demand: &mut core::any::Demand<'a>)
+impl<T, U> core::convert::Into<U> for aya::programs::uprobe::ProcMapError where U: core::convert::From<T>
+pub fn aya::programs::uprobe::ProcMapError::into(self) -> U
+impl<T, U> core::convert::TryFrom<U> for aya::programs::uprobe::ProcMapError where U: core::convert::Into<T>
+pub type aya::programs::uprobe::ProcMapError::Error = core::convert::Infallible
+pub fn aya::programs::uprobe::ProcMapError::try_from(value: U) -> core::result::Result<T, <T as core::convert::TryFrom<U>>::Error>
+impl<T, U> core::convert::TryInto<U> for aya::programs::uprobe::ProcMapError where U: core::convert::TryFrom<T>
+pub type aya::programs::uprobe::ProcMapError::Error = <U as core::convert::TryFrom<T>>::Error
+pub fn aya::programs::uprobe::ProcMapError::try_into(self) -> core::result::Result<U, <U as core::convert::TryFrom<T>>::Error>
+impl<T> alloc::string::ToString for aya::programs::uprobe::ProcMapError where T: core::fmt::Display + core::marker::Sized
+pub fn aya::programs::uprobe::ProcMapError::to_string(&self) -> alloc::string::String
+impl<T> core::any::Any for aya::programs::uprobe::ProcMapError where T: 'static + core::marker::Sized
+pub fn aya::programs::uprobe::ProcMapError::type_id(&self) -> core::any::TypeId
+impl<T> core::borrow::Borrow<T> for aya::programs::uprobe::ProcMapError where T: core::marker::Sized
+pub fn aya::programs::uprobe::ProcMapError::borrow(&self) -> &T
+impl<T> core::borrow::BorrowMut<T> for aya::programs::uprobe::ProcMapError where T: core::marker::Sized
+pub fn aya::programs::uprobe::ProcMapError::borrow_mut(&mut self) -> &mut T
+impl<T> core::convert::From<T> for aya::programs::uprobe::ProcMapError
+pub fn aya::programs::uprobe::ProcMapError::from(t: T) -> T
 pub enum aya::programs::uprobe::UProbeError
 pub aya::programs::uprobe::UProbeError::FileError
 pub aya::programs::uprobe::UProbeError::FileError::filename: alloc::string::String
@@ -4327,6 +4364,9 @@ pub aya::programs::uprobe::UProbeError::InvalidLdSoCache
 pub aya::programs::uprobe::UProbeError::InvalidLdSoCache::io_error: alloc::sync::Arc<std::io::error::Error>
 pub aya::programs::uprobe::UProbeError::InvalidTarget
 pub aya::programs::uprobe::UProbeError::InvalidTarget::path: std::path::PathBuf
+pub aya::programs::uprobe::UProbeError::ProcMap
+pub aya::programs::uprobe::UProbeError::ProcMap::pid: i32
+pub aya::programs::uprobe::UProbeError::ProcMap::source: aya::programs::uprobe::ProcMapError
 pub aya::programs::uprobe::UProbeError::SymbolError
 pub aya::programs::uprobe::UProbeError::SymbolError::error: alloc::boxed::Box<(dyn core::error::Error + core::marker::Send + core::marker::Sync)>
 pub aya::programs::uprobe::UProbeError::SymbolError::symbol: alloc::string::String
@@ -5454,6 +5494,9 @@ pub aya::programs::UProbeError::InvalidLdSoCache
 pub aya::programs::UProbeError::InvalidLdSoCache::io_error: alloc::sync::Arc<std::io::error::Error>
 pub aya::programs::UProbeError::InvalidTarget
 pub aya::programs::UProbeError::InvalidTarget::path: std::path::PathBuf
+pub aya::programs::UProbeError::ProcMap
+pub aya::programs::UProbeError::ProcMap::pid: i32
+pub aya::programs::UProbeError::ProcMap::source: aya::programs::uprobe::ProcMapError
 pub aya::programs::UProbeError::SymbolError
 pub aya::programs::UProbeError::SymbolError::error: alloc::boxed::Box<(dyn core::error::Error + core::marker::Send + core::marker::Sync)>
 pub aya::programs::UProbeError::SymbolError::symbol: alloc::string::String