From 101173d6cf8ddc028a975b3ef369da7d31dd78aa Mon Sep 17 00:00:00 2001 From: Ross Burton Date: Fri, 25 Nov 2016 17:35:03 +0000 Subject: lib/oe/qa: handle binaries with segments outside the first 4kb The ELF parser was assuming that the segment tables are in the first 4kb of the binary. Whilst this generally appears to be the case, there have been instances where the segment table is elsewhere (offset 2MB, in this sample I have). Solve this problem by mmap()ing the file instead. Also clean up the code a little whilst chasing the problem. (From OE-Core rev: b88c6bd61e7c3388b3902de1adb5e48a88f2e235) Signed-off-by: Ross Burton Signed-off-by: Armin Kuster Signed-off-by: Richard Purdie --- meta/lib/oe/qa.py | 82 +++++++++++++++++++++++++++---------------------------- 1 file changed, 41 insertions(+), 41 deletions(-) diff --git a/meta/lib/oe/qa.py b/meta/lib/oe/qa.py index fbe719d8ec..22d76dcbcd 100644 --- a/meta/lib/oe/qa.py +++ b/meta/lib/oe/qa.py @@ -1,4 +1,4 @@ -import os, struct +import os, struct, mmap class NotELFFileError(Exception): pass @@ -23,9 +23,9 @@ class ELFFile: EV_CURRENT = 1 # possible values for EI_DATA - ELFDATANONE = 0 - ELFDATA2LSB = 1 - ELFDATA2MSB = 2 + EI_DATA_NONE = 0 + EI_DATA_LSB = 1 + EI_DATA_MSB = 2 PT_INTERP = 3 @@ -34,51 +34,46 @@ class ELFFile: #print "'%x','%x' %s" % (ord(expectation), ord(result), self.name) raise NotELFFileError("%s is not an ELF" % self.name) - def __init__(self, name, bits = 0): + def __init__(self, name): self.name = name - self.bits = bits self.objdump_output = {} - def open(self): - if not os.path.isfile(self.name): - raise NotELFFileError("%s is not a normal file" % self.name) + # Context Manager functions to close the mmap explicitly + def __enter__(self): + return self + + def __exit__(self, exc_type, exc_value, traceback): + self.data.close() + def open(self): with open(self.name, "rb") as f: - # Read 4k which should cover most of the headers we're after - self.data = f.read(4096) + try: + self.data = mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) + except ValueError: + # This means the file is empty + raise NotELFFileError("%s is empty" % self.name) + # Check the file has the minimum number of ELF table entries if len(self.data) < ELFFile.EI_NIDENT + 4: raise NotELFFileError("%s is not an ELF" % self.name) + # ELF header self.my_assert(self.data[0], 0x7f) self.my_assert(self.data[1], ord('E')) self.my_assert(self.data[2], ord('L')) self.my_assert(self.data[3], ord('F')) - if self.bits == 0: - if self.data[ELFFile.EI_CLASS] == ELFFile.ELFCLASS32: - self.bits = 32 - elif self.data[ELFFile.EI_CLASS] == ELFFile.ELFCLASS64: - self.bits = 64 - else: - # Not 32-bit or 64.. lets assert - raise NotELFFileError("ELF but not 32 or 64 bit.") - elif self.bits == 32: - self.my_assert(self.data[ELFFile.EI_CLASS], ELFFile.ELFCLASS32) - elif self.bits == 64: - self.my_assert(self.data[ELFFile.EI_CLASS], ELFFile.ELFCLASS64) + if self.data[ELFFile.EI_CLASS] == ELFFile.ELFCLASS32: + self.bits = 32 + elif self.data[ELFFile.EI_CLASS] == ELFFile.ELFCLASS64: + self.bits = 64 else: - raise NotELFFileError("Must specify unknown, 32 or 64 bit size.") + # Not 32-bit or 64.. lets assert + raise NotELFFileError("ELF but not 32 or 64 bit.") self.my_assert(self.data[ELFFile.EI_VERSION], ELFFile.EV_CURRENT) - self.sex = self.data[ELFFile.EI_DATA] - if self.sex == ELFFile.ELFDATANONE: - raise NotELFFileError("self.sex == ELFDATANONE") - elif self.sex == ELFFile.ELFDATA2LSB: - self.sex = "<" - elif self.sex == ELFFile.ELFDATA2MSB: - self.sex = ">" - else: - raise NotELFFileError("Unknown self.sex") + self.endian = self.data[ELFFile.EI_DATA] + if self.endian not in (ELFFile.EI_DATA_LSB, ELFFile.EI_DATA_MSB): + raise NotELFFileError("Unexpected EI_DATA %x" % self.endian) def osAbi(self): return self.data[ELFFile.EI_OSABI] @@ -90,16 +85,20 @@ class ELFFile: return self.bits def isLittleEndian(self): - return self.sex == "<" + return self.endian == ELFFile.EI_DATA_LSB def isBigEndian(self): - return self.sex == ">" + return self.endian == ELFFile.EI_DATA_MSB + + def getStructEndian(self): + return {ELFFile.EI_DATA_LSB: "<", + ELFFile.EI_DATA_MSB: ">"}[self.endian] def getShort(self, offset): - return struct.unpack_from(self.sex+"H", self.data, offset)[0] + return struct.unpack_from(self.getStructEndian() + "H", self.data, offset)[0] def getWord(self, offset): - return struct.unpack_from(self.sex+"i", self.data, offset)[0] + return struct.unpack_from(self.getStructEndian() + "i", self.data, offset)[0] def isDynamic(self): """ @@ -118,7 +117,7 @@ class ELFFile: def machine(self): """ - We know the sex stored in self.sex and we + We know the endian stored in self.endian and we know the position """ return self.getShort(ELFFile.E_MACHINE) @@ -166,6 +165,7 @@ def elf_machine_to_string(machine): if __name__ == "__main__": import sys - elf = ELFFile(sys.argv[1]) - elf.open() - print(elf.isDynamic()) + + with ELFFile(sys.argv[1]) as elf: + elf.open() + print(elf.isDynamic()) -- cgit v1.2.3-54-g00ecf