[libcamera-devel] [PATCH v2 1/2] libcamera: ipa_module: add IPA shared library loader
Paul Elder
paul.elder at ideasonboard.com
Wed May 15 00:38:07 CEST 2019
Implement a class to load a struct IPAModuleInfo of a given symbol name
from a .so shared object library.
Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
---
Changes in v2:
- renamed LibLoader class to IPAModule
- added documentation
- added logging
- check that bitness of the shared object is the same as libcamera
- moved symbol loading ("init") to the constructor, and added isValid()
- added elfPointer() to prevent segfaults when reading data from mmap
- moved struct IPAModuleInfo out of IPAModule
- rename getIPAModuleInfo() to IPAModuleInfo(), and make it return a
const reference
- added munmap after the mmap
src/libcamera/include/ipa_module.h | 43 +++++
src/libcamera/ipa_module.cpp | 277 +++++++++++++++++++++++++++++
src/libcamera/meson.build | 2 +
3 files changed, 322 insertions(+)
create mode 100644 src/libcamera/include/ipa_module.h
create mode 100644 src/libcamera/ipa_module.cpp
diff --git a/src/libcamera/include/ipa_module.h b/src/libcamera/include/ipa_module.h
new file mode 100644
index 0000000..9eb0094
--- /dev/null
+++ b/src/libcamera/include/ipa_module.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * ipa_module.h - load IPA module information from shared library at runtime
+ */
+#ifndef __LIBCAMERA_IPA_MODULE_H__
+#define __LIBCAMERA_IPA_MODULE_H__
+
+#include <string>
+
+namespace libcamera {
+
+struct IPAModuleInfo {
+ char name[256];
+ unsigned int version;
+};
+
+class IPAModule
+{
+public:
+ explicit IPAModule(const std::string &libPath, const std::string &symbol);
+
+ bool isValid() const;
+
+ struct IPAModuleInfo const &IPAModuleInfo() const;
+
+private:
+ struct IPAModuleInfo info_;
+
+ bool loaded_;
+ int bitClass_;
+
+ int loadELFIdent(int fd);
+ template<class ElfHeader, class SecHeader, class SymHeader>
+ int loadSymbol(void *data, size_t size, char *map, size_t soSize,
+ const char *symbol);
+ int loadIPAModuleInfo(const char *libPath, const char *symbol);
+};
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_IPA_MODULE_H__ */
diff --git a/src/libcamera/ipa_module.cpp b/src/libcamera/ipa_module.cpp
new file mode 100644
index 0000000..5ca16e8
--- /dev/null
+++ b/src/libcamera/ipa_module.cpp
@@ -0,0 +1,277 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * ipa_module.cpp - load IPA module information from shared library at runtime
+ */
+
+#include "ipa_module.h"
+
+#include <elf.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <iostream>
+
+#include "log.h"
+
+/**
+ * \file ipa_module.h
+ * \brief IPA module information loading
+ */
+
+namespace libcamera {
+
+/**
+ * \struct IPAModuleInfo
+ * \brief Information of an IPA plugin
+ *
+ * This structure contains the information of an IPA plugin. It is loaded,
+ * read, and validated before anything else is loaded from the plugin.
+ *
+ * \var IPAModuleInfo::name
+ * \brief The name of the IPA plugin
+ *
+ * \var IPAModuleInfo::version
+ * \brief The version of the IPA plugin
+ */
+
+LOG_DEFINE_CATEGORY(IPAModule)
+
+template<typename T>
+typename std::remove_extent<T>::type *elfPointer(void *map, off_t offset,
+ size_t fileSize)
+{
+ size_t size = offset + sizeof(T);
+ if (size > fileSize || size < sizeof(T))
+ return nullptr;
+
+ return reinterpret_cast<typename std::remove_extent<T>::type *>
+ (static_cast<char *>(map) + offset);
+}
+
+/**
+ * \class IPAModule
+ * \brief Load IPA module information from an IPA plugin
+ */
+
+/**
+ * \brief Construct an IPAModule instance
+ * \param[in] libPath path to IPA plugin
+ * \param[in] symbol name of IPAModuleInfo to load from libPath
+ *
+ * Loads the IPAModuleInfo of the given symbol from the IPA plugin at libPath.
+ * The IPA plugin shared object file must be of the same endianness and
+ * bitness as libcamera.
+ *
+ * Note that isValid() should be called to check if this loading was successful
+ * or not.
+ */
+
+IPAModule::IPAModule(const std::string &libPath, const std::string &symbol)
+ : loaded_(false)
+{
+ int ret = loadIPAModuleInfo(libPath.c_str(), symbol.c_str());
+ if (ret < 0) {
+ loaded_ = false;
+ return;
+ }
+
+ loaded_ = true;
+}
+
+int IPAModule::loadELFIdent(int fd)
+{
+ int ret = lseek(fd, 0, SEEK_SET);
+ if (ret < 0)
+ return -errno;
+
+ unsigned char e_ident[EI_NIDENT];
+ ret = read(fd, e_ident, EI_NIDENT);
+ if (ret < 0)
+ return -errno;
+
+ if (e_ident[EI_MAG0] != ELFMAG0 ||
+ e_ident[EI_MAG1] != ELFMAG1 ||
+ e_ident[EI_MAG2] != ELFMAG2 ||
+ e_ident[EI_MAG3] != ELFMAG3 ||
+ e_ident[EI_VERSION] != EV_CURRENT)
+ return -ENOEXEC;
+
+ if ((e_ident[EI_CLASS] == ELFCLASS32 && sizeof(unsigned long) == 4) ||
+ (e_ident[EI_CLASS] == ELFCLASS64 && sizeof(unsigned long) == 8))
+ bitClass_ = e_ident[EI_CLASS];
+ else
+ return -ENOEXEC;
+
+ int a = 1;
+ unsigned char endianness = *reinterpret_cast<char *>(&a) == 1
+ ? ELFDATA2LSB : ELFDATA2MSB;
+ if (e_ident[EI_DATA] != endianness)
+ return -ENOEXEC;
+
+ return 0;
+}
+
+template<class ElfHeader, class SecHeader, class SymHeader>
+int IPAModule::loadSymbol(void *dst, size_t size, char *map, size_t soSize,
+ const char *symbol)
+{
+ ElfHeader *eHdr = elfPointer<ElfHeader>(map, 0, soSize);
+ if (!eHdr)
+ return -ENOEXEC;
+
+ off_t offset = eHdr->e_shoff + eHdr->e_shentsize * eHdr->e_shstrndx;
+ SecHeader *sHdr = elfPointer<SecHeader>(map, offset, soSize);
+ if (!sHdr)
+ return -ENOEXEC;
+ off_t shnameoff = sHdr->sh_offset;
+
+ /* Locate .dynsym section header. */
+ bool found = false;
+ SecHeader *dynsym;
+ for (unsigned int i = 0; i < eHdr->e_shnum; i++) {
+ offset = eHdr->e_shoff + eHdr->e_shentsize * i;
+ sHdr = elfPointer<SecHeader>(map, offset, soSize);
+ if (!sHdr)
+ return -ENOEXEC;
+
+ offset = shnameoff + sHdr->sh_name;
+ char *name = elfPointer<char>(map, offset, soSize);
+ if (!name)
+ return -ENOEXEC;
+
+ if (sHdr->sh_type == SHT_DYNSYM && !strcmp(name, ".dynsym")) {
+ found = true;
+ dynsym = sHdr;
+ break;
+ }
+ }
+
+ if (!found) {
+ LOG(IPAModule, Error) << "ELF has no .dynsym section";
+ return -ENOEXEC;
+ }
+
+ offset = eHdr->e_shoff + eHdr->e_shentsize * dynsym->sh_link;
+ sHdr = elfPointer<SecHeader>(map, offset, soSize);
+ if (!sHdr)
+ return -ENOEXEC;
+ off_t dynsym_nameoff = sHdr->sh_offset;
+
+ /* Locate symbol in the .dynsym section. */
+ found = false;
+ SymHeader *target_symbol;
+ unsigned int dynsym_num = dynsym->sh_size / dynsym->sh_entsize;
+ for (unsigned int i = 0; i < dynsym_num; i++) {
+ offset = dynsym->sh_offset + dynsym->sh_entsize * i;
+ SymHeader *sym = elfPointer<SymHeader>(map, offset, soSize);
+ if (!sym)
+ return -ENOEXEC;
+
+ offset = dynsym_nameoff + sym->st_name;
+ char *name = elfPointer<char>(map, offset, soSize);
+ if (!name)
+ return -ENOEXEC;
+
+ if (!strcmp(name, symbol) &&
+ sym->st_info & STB_GLOBAL &&
+ sym->st_size == sizeof(struct IPAModuleInfo)) {
+ found = true;
+ target_symbol = sym;
+ break;
+ }
+ }
+
+ if (!found) {
+ LOG(IPAModule, Error) << "IPAModuleInfo symbol not found";
+ return -ENOEXEC;
+ }
+
+ /* Locate and return data of symbol. */
+ offset = eHdr->e_shoff + target_symbol->st_shndx * eHdr->e_shentsize;
+ sHdr = elfPointer<SecHeader>(map, offset, soSize);
+ if (!sHdr)
+ return -ENOEXEC;
+ offset = sHdr->sh_offset + (target_symbol->st_value - sHdr->sh_addr);
+ char *data = elfPointer<char>(map, offset, soSize);
+ if (!data)
+ return -ENOEXEC;
+ memcpy(dst, data, size);
+
+ return 0;
+}
+
+int IPAModule::loadIPAModuleInfo(const char *libPath, const char *symbol)
+{
+ int fd = open(libPath, O_RDONLY);
+ if (fd < 0) {
+ LOG(IPAModule, Error) << "Failed to open IPA library: "
+ << strerror(errno);
+ return fd;
+ }
+
+ int ret = loadELFIdent(fd);
+ if (ret)
+ goto close;
+
+ size_t soSize;
+ char *map;
+ struct stat st;
+ ret = fstat(fd, &st);
+ if (ret < 0)
+ goto close;
+ soSize = st.st_size;
+ map = static_cast<char *>(mmap(NULL, soSize, PROT_READ,
+ MAP_PRIVATE, fd, 0));
+ if (map == MAP_FAILED) {
+ ret = -errno;
+ goto close;
+ }
+
+ if (bitClass_ == ELFCLASS32)
+ ret = loadSymbol<Elf32_Ehdr, Elf32_Shdr, Elf32_Sym>
+ (&info_, sizeof(info_), map, soSize, symbol);
+ else if (bitClass_ == ELFCLASS64)
+ ret = loadSymbol<Elf64_Ehdr, Elf64_Shdr, Elf64_Sym>
+ (&info_, sizeof(info_), map, soSize, symbol);
+ if (ret)
+ goto unmap;
+
+unmap:
+ munmap(map, soSize);
+close:
+ close(fd);
+ return ret;
+}
+
+/**
+ * \brief Check if construction of the IPAModule instance succeeded
+ *
+ * \return true if the constructor succeeded with no errors, false otherwise
+ */
+
+bool IPAModule::isValid() const
+{
+ return loaded_;
+}
+
+/**
+ * \brief Get the loaded IPAModuleInfo
+ *
+ * Check isValid() before calling this.
+ *
+ * \return IPAModuleInfo
+ */
+
+struct IPAModuleInfo const &IPAModule::IPAModuleInfo() const
+{
+ return info_;
+}
+
+} /* namespace libcamera */
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index 8796f49..e5b48f2 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -10,6 +10,7 @@ libcamera_sources = files([
'event_notifier.cpp',
'formats.cpp',
'geometry.cpp',
+ 'ipa_module.cpp',
'log.cpp',
'media_device.cpp',
'media_object.cpp',
@@ -31,6 +32,7 @@ libcamera_headers = files([
'include/device_enumerator_udev.h',
'include/event_dispatcher_poll.h',
'include/formats.h',
+ 'include/ipa_module.h',
'include/log.h',
'include/media_device.h',
'include/media_object.h',
--
2.20.1
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