QElfParser: rewrite using elf.h

This rewrite uses the actual structures supplied by the system's C
library, so it should be easier to read. It removes hardcoded constants
with little evident meaning in favor of sizeof() and the macros from
that header. It also removes advancing the data pointer in favor of
having absolute offsets.

The resulting implementation is stricter than the original, checking
more fields in the header. Because the QPluginLoader and QFactoryLoader
users may make decisions based on availability of plugins before
attempting to load them, it's better to be stricter here than to fail
later when trying to dlopen() them.

Debugging and testing are much improved. Instead of stored artifacts, I
added a routine to modify a valid plugin to make it invalid, given the
conditions we've found so far.

If you turn debugging on for this category, you'll see things like:

 not-elf.fcqdMq.so : Not an ELF file (invalid signature)
 wrong-word-size.QrnSAx.so : ELF 32-bit LSB (GNU/Linux), version 1, shared library or PIC executable, x86-64
 invalid-word-size.bOkXvp.so : Invalid ELF file (class 0), LSB (GNU/Linux)
 unknown-word-size.ogYKeF.so : Invalid ELF file (class 66), LSB (GNU/Linux)
 wrong-endian.owiElX.so : ELF 64-bit MSB (GNU/Linux), version 1, shared library or PIC executable, x86-64
 invalid-endian.FRxClR.so : ELF 64-bit invalid endianness (0) (GNU/Linux)
 unknown-endian.FfvRrP.so : ELF 64-bit invalid endianness (65) (GNU/Linux)
 elf-version-0.gPTdpQ.so : ELF 64-bit LSB (GNU/Linux), file version 0
 elf-version-2.jlIUUg.so : ELF 64-bit LSB (GNU/Linux), file version 2
 executable.LlXiFp.so : ELF 64-bit LSB (GNU/Linux), version 1, executable, x86-64
 relocatable.UsOYuy.so : ELF 64-bit LSB (GNU/Linux), version 1, relocatable, x86-64
 core-file.hqvNRz.so : ELF 64-bit LSB (GNU/Linux), version 1, core dump, x86-64
 invalid-type.CIJgfS.so : ELF 64-bit LSB (GNU/Linux), version 1, unknown type 259, x86-64
 wrong-arch.UcNmgz.so : ELF 64-bit LSB (GNU/Linux), version 1, shared library or PIC executable, AArch64
 file-version-0.lZYuda.so : ELF 64-bit LSB (GNU/Linux), version 0, shared library or PIC executable, x86-64
 file-version-2.ucfdwL.so : ELF 64-bit LSB (GNU/Linux), version 2, shared library or PIC executable, x86-64
 no-sections.rSjsHh.so : ELF 64-bit LSB (GNU/Linux), version 1, shared library or PIC executable, x86-64
 no-sections.rSjsHh.so : contains 0 sections of 64 bytes at offset 0 ; section header string table (shstrtab) is entry 0
 no-sections.rSjsHh.so : no section table present, not able to find Qt metadata
 qtmetadata-executable.vrxcIf.so : ELF 64-bit LSB (GNU/Linux), version 1, shared library or PIC executable, x86-64
 qtmetadata-executable.vrxcIf.so : contains 42 sections of 64 bytes at offset 997256 ; section header string table (shstrtab) is entry 41
 qtmetadata-executable.vrxcIf.so : shstrtab section is located at offset 996831 size 423
 qtmetadata-executable.vrxcIf.so : section 0 name "" type NULL flags X offset 0x0 size 0x0
 qtmetadata-executable.vrxcIf.so : section 1 name ".note.gnu.property" type NOTE flags AX offset 0x2a8 size 0x30
 qtmetadata-executable.vrxcIf.so : section 2 name ".note.gnu.build-id" type NOTE flags AX offset 0x2d8 size 0x24
 qtmetadata-executable.vrxcIf.so : section 3 name ".hash" type HASH flags AX offset 0x300 size 0x44c
 qtmetadata-executable.vrxcIf.so : section 4 name ".gnu.hash" type 0x6ffffff6 flags AX offset 0x750 size 0x3b8
 qtmetadata-executable.vrxcIf.so : section 5 name ".dynsym" type DYNSYM flags AX offset 0xb08 size 0xd50
 qtmetadata-executable.vrxcIf.so : section 6 name ".dynstr" type STRTAB flags AX offset 0x1858 size 0x15d8
 qtmetadata-executable.vrxcIf.so : section 7 name ".gnu.version" type 0x6fffffff flags AX offset 0x2e30 size 0x11c
 qtmetadata-executable.vrxcIf.so : section 8 name ".gnu.version_r" type 0x6ffffffe flags AX offset 0x2f50 size 0xb0
 qtmetadata-executable.vrxcIf.so : section 9 name ".rela.dyn" type RELA flags AX offset 0x3000 size 0x480
 qtmetadata-executable.vrxcIf.so : section 10 name ".rela.plt" type RELA flags AX offset 0x3480 size 0x7e0
 qtmetadata-executable.vrxcIf.so : section 11 name ".init" type PROGBITS flags AX offset 0x4000 size 0x1b
 qtmetadata-executable.vrxcIf.so : section 12 name ".plt" type PROGBITS flags AX offset 0x4020 size 0x550
 qtmetadata-executable.vrxcIf.so : section 13 name ".plt.got" type PROGBITS flags AX offset 0x4570 size 0x8
 qtmetadata-executable.vrxcIf.so : section 14 name ".text" type PROGBITS flags AX offset 0x4580 size 0x110e
 qtmetadata-executable.vrxcIf.so : section 15 name ".fini" type PROGBITS flags AX offset 0x5690 size 0xd
 qtmetadata-executable.vrxcIf.so : section 16 name ".rodata" type PROGBITS flags AX offset 0x6000 size 0x473
 qtmetadata-executable.vrxcIf.so : section 17 name ".qtversion" type PROGBITS flags AX offset 0x6478 size 0x10
 qtmetadata-executable.vrxcIf.so : section 18 name ".qtmetadata" type PROGBITS flags AX offset 0x64a0 size 0x19b
 qtmetadata-executable.vrxcIf.so : found .qtmetadata section
 qtmetadata-writable.stzwrk.so : ELF 64-bit LSB (GNU/Linux), version 1, shared library or PIC executable, x86-64

Change-Id: I42eb903a916645db9900fffd16a4437af9728eea
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/corelib/plugin/qlibrary.cpp b/src/corelib/plugin/qlibrary.cpp
index 1df6dfeb08..a8c6644bfd 100644
--- a/src/corelib/plugin/qlibrary.cpp
+++ b/src/corelib/plugin/qlibrary.cpp
@@ -193,8 +193,8 @@ static QLibraryScanResult qt_find_pattern(const char *s, qsizetype s_len, QStrin
       More importantly, the pattern string may exist in the debug information due
       to it being used in the plugin in the first place.
     */
-#if defined (Q_OF_ELF)
-    return QElfParser().parse(s, s_len, errMsg);
+#if defined (Q_OF_ELF) && __has_include(<elf.h>)
+    return QElfParser::parse({s, s_len}, errMsg);
 #elif defined(Q_OF_MACH_O)
     return QMachOParser::parse(s, s_len, errMsg);
 #endif