Initial import of libdpf.

Co-authored-by: Cursor <cursoragent@cursor.com>

thirdparty/portable-snippets/debug-trap/README.md

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+# Debugging assertions and traps
+
+This is an attempt to provide a fairly portable way to generate traps
+in code. `__builtin_trap` is `_Noreturn`, so the compiler may optimize
+away code found after it, which means you can't really drop into a
+debugger and step through the code after the trap has been hit.
+
+If `PSNIP_NDEBUG` is defined, or `NDEBUG` is defined and `PSNIP_DEBUG`
+is not, `psnip_dbg_assert(expr)` will be preprocessed to nothing
+(i.e., `expr` will not be evaluated). Otherwise it will call
+`psnip_trap` if `expr` evaluates to false.
+
+Knowledge about how to do this portably basically comes from:
+
+ * [scottt/debugbreak](https://github.com/scottt/debugbreak/).
+ * GLib's [G_BREAKPOINT](https://developer.gnome.org/glib/stable/glib-Warnings-and-Assertions.html#G-BREAKPOINT:CAPS) macro.
+ * [TI's Wiki](http://processors.wiki.ti.com/index.php/Software_Breakpoints_in_the_IDE)
+ * Assorted compiler documentation.
+
+On non-hosted platforms we *may* have to fall back on
+`__builtin_trap`. On non-hosted non-GNU-compatible compilers on
+relatively exotic architectures you may end up with an error about
+stdlib.h being missing... if you have a good way to resolve that on
+your platform please contact us.

thirdparty/portable-snippets/debug-trap/debug-trap.h

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+/* Debugging assertions and traps
+ * Portable Snippets - https://github.com/nemequ/portable-snippets
+ * Created by Evan Nemerson <evan@nemerson.com>
+ *
+ *   To the extent possible under law, the authors have waived all
+ *   copyright and related or neighboring rights to this code.  For
+ *   details, see the Creative Commons Zero 1.0 Universal license at
+ *   https://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+#if !defined(PSNIP_DEBUG_TRAP_H)
+#define PSNIP_DEBUG_TRAP_H
+
+#if !defined(PSNIP_NDEBUG) && defined(NDEBUG) && !defined(PSNIP_DEBUG)
+#  define PSNIP_NDEBUG 1
+#endif
+
+#if defined(__has_builtin) && !defined(__ibmxl__)
+#  if __has_builtin(__builtin_debugtrap)
+#    define psnip_trap() __builtin_debugtrap()
+#  elif __has_builtin(__debugbreak)
+#    define psnip_trap() __debugbreak()
+#  endif
+#endif
+#if !defined(psnip_trap)
+#  if defined(_MSC_VER) || defined(__INTEL_COMPILER)
+#    define psnip_trap() __debugbreak()
+#  elif defined(__ARMCC_VERSION)
+#    define psnip_trap() __breakpoint(42)
+#  elif defined(__ibmxl__) || defined(__xlC__)
+#    include <builtins.h>
+#    define psnip_trap() __trap(42)
+#  elif defined(__DMC__) && defined(_M_IX86)
+     static inline void psnip_trap(void) { __asm int 3h; }
+#  elif defined(__i386__) || defined(__x86_64__)
+     static inline void psnip_trap(void) { __asm__ __volatile__("int3"); }
+#  elif defined(__thumb__)
+     static inline void psnip_trap(void) { __asm__ __volatile__(".inst 0xde01"); }
+#  elif defined(__aarch64__)
+     static inline void psnip_trap(void) { __asm__ __volatile__(".inst 0xd4200000"); }
+#  elif defined(__arm__)
+     static inline void psnip_trap(void) { __asm__ __volatile__(".inst 0xe7f001f0"); }
+#  elif defined (__alpha__) && !defined(__osf__)
+     static inline void psnip_trap(void) { __asm__ __volatile__("bpt"); }
+#  elif defined(_54_)
+     static inline void psnip_trap(void) { __asm__ __volatile__("ESTOP"); }
+#  elif defined(_55_)
+     static inline void psnip_trap(void) { __asm__ __volatile__(";\n .if (.MNEMONIC)\n ESTOP_1\n .else\n ESTOP_1()\n .endif\n NOP"); }
+#  elif defined(_64P_)
+     static inline void psnip_trap(void) { __asm__ __volatile__("SWBP 0"); }
+#  elif defined(_6x_)
+     static inline void psnip_trap(void) { __asm__ __volatile__("NOP\n .word 0x10000000"); }
+#  elif defined(__STDC_HOSTED__) && (__STDC_HOSTED__ == 0) && defined(__GNUC__)
+#    define psnip_trap() __builtin_trap()
+#  else
+#    include <signal.h>
+#    if defined(SIGTRAP)
+#      define psnip_trap() raise(SIGTRAP)
+#    else
+#      define psnip_trap() raise(SIGABRT)
+#    endif
+#  endif
+#endif
+
+#if defined(HEDLEY_LIKELY)
+#  define PSNIP_DBG_LIKELY(expr) HEDLEY_LIKELY(expr)
+#elif defined(__GNUC__) && (__GNUC__ >= 3)
+#  define PSNIP_DBG_LIKELY(expr) __builtin_expect(!!(expr), 1)
+#else
+#  define PSNIP_DBG_LIKELY(expr) (!!(expr))
+#endif
+
+#if !defined(PSNIP_NDEBUG) || (PSNIP_NDEBUG == 0)
+#  define psnip_dbg_assert(expr) do { \
+    if (!PSNIP_DBG_LIKELY(expr)) { \
+      psnip_trap(); \
+    } \
+  } while (0)
+#else
+#  define psnip_dbg_assert(expr)
+#endif
+
+#endif /* !defined(PSNIP_DEBUG_TRAP_H) */