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https://github.com/JakeHillion/drgn.git
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75c3679147
The current mixed Python/C implementation works well, but it has a couple of important limitations: - It's too slow for some common use cases, like iterating over large data structures. - It can't be reused in utilities written in other languages. This replaces the internals with a new library written in C, libdrgn. It includes Python bindings with mostly the same public interface as before, with some important improvements: - Types are now represented by a single Type class rather than the messy polymorphism in the Python implementation. - Qualifiers are a bitmask instead of a set of strings. - Bit fields are not considered a separate type. - The lvalue/rvalue terminology is replaced with reference/value. - Structure, union, and array values are better supported. - Function objects are supported. - Program distinguishes between lookups of variables, constants, and functions. The C rewrite is about 6x as fast as the original Python when using the Python bindings, and about 8x when using the C API directly. Currently, the exposed API in C is fairly conservative. In the future, the memory reader, type index, and object index APIs will probably be exposed for more flexibility.
63 lines
1.4 KiB
C
63 lines
1.4 KiB
C
// Copyright 2018-2019 - Omar Sandoval
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// SPDX-License-Identifier: GPL-3.0+
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#include "internal.h"
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/* This definition was added to elf.h in glibc 2.22. */
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#ifndef SHF_COMPRESSED
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#define SHF_COMPRESSED (1 << 11)
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#endif
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/*
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* glibc added reallocarray() in 2.26, but since it's so trivial, it's easier to
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* duplicate it here than it is to do feature detection.
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*/
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void *realloc_array(void *ptr, size_t nmemb, size_t size)
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{
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size_t bytes;
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if (__builtin_mul_overflow(nmemb, size, &bytes)) {
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errno = ENOMEM;
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return NULL;
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}
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return realloc(ptr, bytes);
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}
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void *malloc_array(size_t nmemb, size_t size)
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{
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size_t bytes;
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if (__builtin_mul_overflow(nmemb, size, &bytes)) {
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errno = ENOMEM;
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return NULL;
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}
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return malloc(bytes);
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}
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struct drgn_error *read_elf_section(Elf_Scn *scn, Elf_Data **ret)
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{
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GElf_Shdr shdr_mem, *shdr;
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Elf_Data *data;
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shdr = gelf_getshdr(scn, &shdr_mem);
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if (!shdr)
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return drgn_error_libelf();
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if (shdr->sh_flags & SHF_COMPRESSED) {
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#if _ELFUTILS_PREREQ(0, 165)
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if (elf_compress(scn, 0, 0) < 0)
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return drgn_error_libelf();
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shdr = gelf_getshdr(scn, &shdr_mem);
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if (!shdr)
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return drgn_error_libelf();
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#else
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return drgn_error_create(DRGN_ERROR_ELF_FORMAT,
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"section is compressed but libelf does not support decompression");
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#endif
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}
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data = elf_getdata(scn, NULL);
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if (!data)
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return drgn_error_libelf();
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*ret = data;
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return NULL;
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}
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