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Code Issues Wiki Activity

Bug 561789 - Introduce ElfSymbolIterator

Browse source 
This allows symbol reading on larger executables without
hitting an out of memory error

Note: this should not close the bug, it is just a first step.

Change-Id: I62bb252ff67d88d9bef686760fdc0e9b8240fd02
Signed-off-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
This commit is contained in:
Matthew Khouzam 2020-05-08 13:58:28 -04:00 • committed by Alexander Fedorov
parent 3201a07fc3
commit 84e9a78109
2 changed files with 131 additions and 41 deletions
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22
core/org.eclipse.cdt.core/utils/org/eclipse/cdt/utils/ERandomAccessFile.java
View file

@ -17,6 +17,7 @@ import java.io.EOFException;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteOrder;
/**
* @noextend This class is not intended to be subclassed by clients.
@ -25,13 +26,15 @@ public class ERandomAccessFile extends RandomAccessFile {
private boolean isle;
private long ptr_offset;
int val[] = new int[4];
private final String path;
public ERandomAccessFile(String file, String mode) throws IOException {
super(file, mode);
path = file;
}
public ERandomAccessFile(File file, String mode) throws IOException {
super(file, mode);
this(file.getPath(), mode);
}
public void setEndian(boolean le) {
@ -100,6 +103,14 @@ public class ERandomAccessFile extends RandomAccessFile {
super.seek(offset);
}
/**
* Get the path of the file reader
* @since 6.12
*/
public String getPath() {
return path;
}
@Override
public long getFilePointer() throws IOException {
long ptr = super.getFilePointer();
@ -112,4 +123,13 @@ public class ERandomAccessFile extends RandomAccessFile {
long real_pos = pos + ptr_offset;
super.seek(real_pos);
}
/**
* Get the byte order of the file
* @return {@link ByteOrder#LITTLE_ENDIAN} or {@link ByteOrder#BIG_ENDIAN}
* @since 6.12
*/
public ByteOrder order() {
return isle ? ByteOrder.LITTLE_ENDIAN : ByteOrder.BIG_ENDIAN;
}
}

150
core/org.eclipse.cdt.core/utils/org/eclipse/cdt/utils/elf/Elf.java
View file

@ -18,13 +18,17 @@ import static org.eclipse.cdt.internal.core.ByteUtils.makeInt;
import static org.eclipse.cdt.internal.core.ByteUtils.makeLong;
import static org.eclipse.cdt.internal.core.ByteUtils.makeShort;
import java.io.Closeable;
import java.io.EOFException;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.channels.FileChannel.MapMode;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.eclipse.cdt.core.CCorePlugin;
import org.eclipse.cdt.core.IAddress;
@ -58,6 +62,7 @@ public class Elf {
private boolean areSectionsMapped; // Have sections been mapped? Used to clean up properly in Elf.Dispose.
protected String EMPTY_STRING = ""; //$NON-NLS-1$
private long elfOffset;
public class ELFhdr {
@ -696,6 +701,7 @@ public class Elf {
public Elf(String file, long offset) throws IOException {
commonSetup(file, offset);
elfOffset = offset;
}
public Elf(String file) throws IOException {
@ -971,7 +977,6 @@ public class Elf {
if (efile != null) {
efile.close();
efile = null;
// ensure the mappings get cleaned up
if (areSectionsMapped)
System.gc();
@ -1073,6 +1078,93 @@ public class Elf {
return sections;
}
/**
* Symbol iterator, iterates over an elf file. Note: the iterator must be closed at the end in order to avoid resource leaks.
*
* TODO: move to another file when @link {@Link Symbol} can be made static.
*/
private class ElfSectionIterator implements Iterator<Symbol>, Closeable {
private final int nbSymbols;
private final ERandomAccessFile innerEfile;
private final Section section;
private final byte arch;
private int position = 0;
public ElfSectionIterator(ERandomAccessFile eFile, byte b, Section sectionToRead, byte architecture)
throws IOException {
int numSyms = 1;
section = sectionToRead;
if (section.sh_entsize != 0) {
numSyms = (int) section.sh_size / (int) section.sh_entsize;
}
section.makeSureNotCompressed();
nbSymbols = numSyms;
innerEfile = new ERandomAccessFile(eFile.getPath(), "r"); //$NON-NLS-1$
innerEfile.setFileOffset(elfOffset);
innerEfile.setEndian(efile.order() == ByteOrder.LITTLE_ENDIAN);
arch = architecture;
}
@Override
public boolean hasNext() {
return position < nbSymbols;
}
@Override
public Symbol next() {
long innerOffset = section.sh_entsize * position + section.sh_offset;
position++;
try {
innerEfile.seek(innerOffset);
Symbol symbol = new Symbol(section);
switch (arch) {
case ELFhdr.ELFCLASS32: {
byte[] addrArray = new byte[ELF32_ADDR_SIZE];
symbol.st_name = innerEfile.readIntE();
innerEfile.readFullyE(addrArray);
symbol.st_value = new Addr32(addrArray);
symbol.st_size = innerEfile.readIntE();
symbol.st_info = innerEfile.readByte();
symbol.st_other = innerEfile.readByte();
symbol.st_shndx = innerEfile.readShortE();
break;
}
case ELFhdr.ELFCLASS64: {
byte[] addrArray = new byte[ELF64_ADDR_SIZE];
symbol.st_name = innerEfile.readIntE();
symbol.st_info = innerEfile.readByte();
symbol.st_other = innerEfile.readByte();
symbol.st_shndx = innerEfile.readShortE();
innerEfile.readFullyE(addrArray);
symbol.st_value = new Addr64(addrArray);
symbol.st_size = innerEfile.readLongE();
if (symbol.st_size < 0) {
throw new NoSuchElementException("Maximal file offset is " + Long.toHexString(Long.MAX_VALUE) + //$NON-NLS-1$
" given offset is " + Long.toHexString(symbol.st_size)); //$NON-NLS-1$
}
break;
}
case ELFhdr.ELFCLASSNONE:
default:
throw new NoSuchElementException("Unknown ELF class " + arch); //$NON-NLS-1$
}
return symbol;
} catch (IOException e) {
throw new NoSuchElementException(e.getMessage());
}
}
@Override
public void close() throws IOException {
innerEfile.close();
}
}
private Symbol[] loadSymbolsBySection(Section section) throws IOException {
int numSyms = 1;
if (section.sh_entsize != 0) {
@ -1080,48 +1172,30 @@ public class Elf {
}
section.makeSureNotCompressed();
ArrayList<Symbol> symList = new ArrayList<>(numSyms);
long offset = section.sh_offset;
for (int c = 0; c < numSyms; offset += section.sh_entsize, c++) {
efile.seek(offset);
Symbol symbol = new Symbol(section);
switch (ehdr.e_ident[ELFhdr.EI_CLASS]) {
case ELFhdr.ELFCLASS32: {
byte[] addrArray = new byte[ELF32_ADDR_SIZE];
symbol.st_name = efile.readIntE();
efile.readFullyE(addrArray);
symbol.st_value = new Addr32(addrArray);
symbol.st_size = efile.readIntE();
symbol.st_info = efile.readByte();
symbol.st_other = efile.readByte();
symbol.st_shndx = efile.readShortE();
try (ElfSectionIterator elfIterator = symbolIterator(section)) {
while (elfIterator.hasNext()) {
Symbol symbol = elfIterator.next();
if (symbol.st_info == 0)
continue;
symList.add(symbol);
}
break;
case ELFhdr.ELFCLASS64: {
byte[] addrArray = new byte[ELF64_ADDR_SIZE];
symbol.st_name = efile.readIntE();
symbol.st_info = efile.readByte();
symbol.st_other = efile.readByte();
symbol.st_shndx = efile.readShortE();
efile.readFullyE(addrArray);
symbol.st_value = new Addr64(addrArray);
symbol.st_size = readUnsignedLong(efile);
}
break;
case ELFhdr.ELFCLASSNONE:
default:
throw new IOException("Unknown ELF class " + ehdr.e_ident[ELFhdr.EI_CLASS]); //$NON-NLS-1$
}
if (symbol.st_info == 0)
continue;
symList.add(symbol);
}
Symbol[] results = symList.toArray(new Symbol[0]);
Arrays.sort(results);
return results;
}
/**
* Get a symbol iterator
* @param section the section to iterate over
* @return an iterator that returns symbols of a given section
* @throws IOException If the file is corrupt
* @since 6.12
*/
public ElfSectionIterator symbolIterator(Section section) throws IOException {
return new ElfSectionIterator(efile, ehdr.e_ident[ELFhdr.EI_CLASS], section, ehdr.e_ident[ELFhdr.EI_CLASS]);
}
public void loadSymbols() throws IOException {
Section symbolsTableSection = null;
Section dynamicSymbolSection = null;
@ -1131,7 +1205,6 @@ public class Elf {
symbolsTableSection = section[0];
symbolsTable = loadSymbolsBySection(section[0]);
} else {
symbolsTableSection = null;
symbolsTable = new Symbol[0];
}
@ -1140,15 +1213,12 @@ public class Elf {
dynamicSymbolSection = section[0];
dynamicSymbols = loadSymbolsBySection(section[0]);
} else {
dynamicSymbolSection = null;
dynamicSymbols = new Symbol[0];
}
if (symbolsTableSection != null) {
// sym = symtab_sym;
symbols = symbolsTable;
} else if (dynamicSymbolSection != null) {
// sym = dynsym_sym;
symbols = dynamicSymbols;
}
}