1 files changed, 224 insertions, 0 deletions
diff --git a/vendor/object/src/read/elf/hash.rs b/vendor/object/src/read/elf/hash.rs
new file mode 100644
index 0000000..b0130cc
--- /dev/null
+++ b/vendor/object/src/read/elf/hash.rs
@@ -0,0 +1,224 @@
+use core::mem;
+
+use crate::elf;
+use crate::read::{ReadError, ReadRef, Result};
+use crate::{U32, U64};
+
+use super::{FileHeader, Sym, SymbolTable, Version, VersionTable};
+
+/// A SysV symbol hash table in an ELF file.
+///
+/// Returned by [`SectionHeader::hash`](super::SectionHeader::hash).
+#[derive(Debug)]
+pub struct HashTable<'data, Elf: FileHeader> {
+    buckets: &'data [U32<Elf::Endian>],
+    chains: &'data [U32<Elf::Endian>],
+}
+
+impl<'data, Elf: FileHeader> HashTable<'data, Elf> {
+    /// Parse a SysV hash table.
+    ///
+    /// `data` should be from an [`elf::SHT_HASH`] section, or from a
+    /// segment pointed to via the [`elf::DT_HASH`] entry.
+    ///
+    /// The header is read at offset 0 in the given `data`.
+    pub fn parse(endian: Elf::Endian, data: &'data [u8]) -> Result<Self> {
+        let mut offset = 0;
+        let header = data
+            .read::<elf::HashHeader<Elf::Endian>>(&mut offset)
+            .read_error("Invalid hash header")?;
+        let buckets = data
+            .read_slice(&mut offset, header.bucket_count.get(endian) as usize)
+            .read_error("Invalid hash buckets")?;
+        let chains = data
+            .read_slice(&mut offset, header.chain_count.get(endian) as usize)
+            .read_error("Invalid hash chains")?;
+        Ok(HashTable { buckets, chains })
+    }
+
+    /// Return the symbol table length.
+    pub fn symbol_table_length(&self) -> u32 {
+        self.chains.len() as u32
+    }
+
+    /// Use the hash table to find the symbol table entry with the given name, hash and version.
+    pub fn find<R: ReadRef<'data>>(
+        &self,
+        endian: Elf::Endian,
+        name: &[u8],
+        hash: u32,
+        version: Option<&Version<'_>>,
+        symbols: &SymbolTable<'data, Elf, R>,
+        versions: &VersionTable<'data, Elf>,
+    ) -> Option<(usize, &'data Elf::Sym)> {
+        // Get the chain start from the bucket for this hash.
+        let mut index = self.buckets[(hash as usize) % self.buckets.len()].get(endian) as usize;
+        // Avoid infinite loop.
+        let mut i = 0;
+        let strings = symbols.strings();
+        while index != 0 && i < self.chains.len() {
+            if let Ok(symbol) = symbols.symbol(index) {
+                if symbol.name(endian, strings) == Ok(name)
+                    && versions.matches(endian, index, version)
+                {
+                    return Some((index, symbol));
+                }
+            }
+            index = self.chains.get(index)?.get(endian) as usize;
+            i += 1;
+        }
+        None
+    }
+}
+
+/// A GNU symbol hash table in an ELF file.
+///
+/// Returned by [`SectionHeader::gnu_hash`](super::SectionHeader::gnu_hash).
+#[derive(Debug)]
+pub struct GnuHashTable<'data, Elf: FileHeader> {
+    symbol_base: u32,
+    bloom_shift: u32,
+    bloom_filters: &'data [u8],
+    buckets: &'data [U32<Elf::Endian>],
+    values: &'data [U32<Elf::Endian>],
+}
+
+impl<'data, Elf: FileHeader> GnuHashTable<'data, Elf> {
+    /// Parse a GNU hash table.
+    ///
+    /// `data` should be from an [`elf::SHT_GNU_HASH`] section, or from a
+    /// segment pointed to via the [`elf::DT_GNU_HASH`] entry.
+    ///
+    /// The header is read at offset 0 in the given `data`.
+    ///
+    /// The header does not contain a length field, and so all of `data`
+    /// will be used as the hash table values. It does not matter if this
+    /// is longer than needed, and this will often the case when accessing
+    /// the hash table via the [`elf::DT_GNU_HASH`] entry.
+    pub fn parse(endian: Elf::Endian, data: &'data [u8]) -> Result<Self> {
+        let mut offset = 0;
+        let header = data
+            .read::<elf::GnuHashHeader<Elf::Endian>>(&mut offset)
+            .read_error("Invalid GNU hash header")?;
+        let bloom_len =
+            u64::from(header.bloom_count.get(endian)) * mem::size_of::<Elf::Word>() as u64;
+        let bloom_filters = data
+            .read_bytes(&mut offset, bloom_len)
+            .read_error("Invalid GNU hash bloom filters")?;
+        let buckets = data
+            .read_slice(&mut offset, header.bucket_count.get(endian) as usize)
+            .read_error("Invalid GNU hash buckets")?;
+        let chain_count = (data.len() - offset as usize) / 4;
+        let values = data
+            .read_slice(&mut offset, chain_count)
+            .read_error("Invalid GNU hash values")?;
+        Ok(GnuHashTable {
+            symbol_base: header.symbol_base.get(endian),
+            bloom_shift: header.bloom_shift.get(endian),
+            bloom_filters,
+            buckets,
+            values,
+        })
+    }
+
+    /// Return the symbol table index of the first symbol in the hash table.
+    pub fn symbol_base(&self) -> u32 {
+        self.symbol_base
+    }
+
+    /// Determine the symbol table length by finding the last entry in the hash table.
+    ///
+    /// Returns `None` if the hash table is empty or invalid.
+    pub fn symbol_table_length(&self, endian: Elf::Endian) -> Option<u32> {
+        // Ensure we find a non-empty bucket.
+        if self.symbol_base == 0 {
+            return None;
+        }
+
+        // Find the highest chain index in a bucket.
+        let mut max_symbol = 0;
+        for bucket in self.buckets {
+            let bucket = bucket.get(endian);
+            if max_symbol < bucket {
+                max_symbol = bucket;
+            }
+        }
+
+        // Find the end of the chain.
+        for value in self
+            .values
+            .get(max_symbol.checked_sub(self.symbol_base)? as usize..)?
+        {
+            max_symbol += 1;
+            if value.get(endian) & 1 != 0 {
+                return Some(max_symbol);
+            }
+        }
+
+        None
+    }
+
+    /// Use the hash table to find the symbol table entry with the given name, hash, and version.
+    pub fn find<R: ReadRef<'data>>(
+        &self,
+        endian: Elf::Endian,
+        name: &[u8],
+        hash: u32,
+        version: Option<&Version<'_>>,
+        symbols: &SymbolTable<'data, Elf, R>,
+        versions: &VersionTable<'data, Elf>,
+    ) -> Option<(usize, &'data Elf::Sym)> {
+        let word_bits = mem::size_of::<Elf::Word>() as u32 * 8;
+
+        // Test against bloom filter.
+        let bloom_count = self.bloom_filters.len() / mem::size_of::<Elf::Word>();
+        let offset =
+            ((hash / word_bits) & (bloom_count as u32 - 1)) * mem::size_of::<Elf::Word>() as u32;
+        let filter = if word_bits == 64 {
+            self.bloom_filters
+                .read_at::<U64<Elf::Endian>>(offset.into())
+                .ok()?
+                .get(endian)
+        } else {
+            self.bloom_filters
+                .read_at::<U32<Elf::Endian>>(offset.into())
+                .ok()?
+                .get(endian)
+                .into()
+        };
+        if filter & (1 << (hash % word_bits)) == 0 {
+            return None;
+        }
+        if filter & (1 << ((hash >> self.bloom_shift) % word_bits)) == 0 {
+            return None;
+        }
+
+        // Get the chain start from the bucket for this hash.
+        let mut index = self.buckets[(hash as usize) % self.buckets.len()].get(endian) as usize;
+        if index == 0 {
+            return None;
+        }
+
+        // Test symbols in the chain.
+        let strings = symbols.strings();
+        let symbols = symbols.symbols().get(index..)?;
+        let values = self
+            .values
+            .get(index.checked_sub(self.symbol_base as usize)?..)?;
+        for (symbol, value) in symbols.iter().zip(values.iter()) {
+            let value = value.get(endian);
+            if value | 1 == hash | 1 {
+                if symbol.name(endian, strings) == Ok(name)
+                    && versions.matches(endian, index, version)
+                {
+                    return Some((index, symbol));
+                }
+            }
+            if value & 1 != 0 {
+                break;
+            }
+            index += 1;
+        }
+        None
+    }
+}