/*
    Copyright (C) 2010  ABRT team
    Copyright (C) 2010  RedHat Inc

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    Authors:
       Anton Arapov <anton@redhat.com>
       Arjan van de Ven <arjan@linux.intel.com>
 */

#include "abrtlib.h"
#include "Kerneloops.h"
#include "DebugDump.h"
#include "ABRTException.h"
#include "CommLayerInner.h"

static unsigned hash_oops_str(const char *oops_ptr)
{
	unsigned char old_c;
	unsigned char c = 0;
	unsigned hash = 0;
	while (1)
	{
		old_c = c;
		c = *oops_ptr++;
		if (!c)
			break;
		if (c == '\n') {
			// Exclude some lines which have process name - in some oops classes
			// process name is irrelevant and changes with every oops.
			// Lines we filter out:
			// Pid: 8003, comm: Xorg Not tainted (2.6.27.9-159.fc10.i686 #1)
			// Process Xorg (pid: 8003, ti=f0a0c000 task=f2380000 task.ti=f0a0c000)
			if (strncmp(oops_ptr, "Pid: ", 5) == 0
			 || strncmp(oops_ptr, "Process ", 8) == 0
			) {
				while (*oops_ptr && *oops_ptr != '\n')
					oops_ptr++;
				continue;
			}
		}
		if (!isalnum(old_c)) {
			if (c >= '0' && c <= '9') {
				// Convert all (possibly hex) numbers to just one '0'
				if (c == '0' && *oops_ptr == 'x') // "0xSOMETHING"
					oops_ptr++;
				while (isxdigit(*oops_ptr))
					oops_ptr++;
				c = '0';
			} else
			if ((c|0x20) >= 'a' && (c|0x20) <= 'f') {
				// This *may be* a hex number without 0x prefix: "f0a0c000"
				// Check that it indeed is, and replace with '0'
				const char *oops_ptr2 = oops_ptr;
				while (isxdigit(*oops_ptr2))
					oops_ptr2++;
				// Does it end in a letter which is not a hex digit?
				// (Example: "abcw" is not a hex number, "abc " is)
				if (!isalpha(*oops_ptr2)) {
					// It's "abc " case. Skip the "abc" string
					oops_ptr = oops_ptr2;
					c = '0';
				}
				// else: hash the string as-is
			}
		}
		// TODO: Drop call trace tail - in interrupt-driven oopses,
		// everything before interrupt is irrelevant.
		// Example of call trace part of oops:
		// Call Trace:
		// [<f88e11c7>] ? radeon_cp_resume+0x7d/0xbc [radeon]
		// [<f88745f8>] ? drm_ioctl+0x1b0/0x225 [drm]
		// [<f88e114a>] ? radeon_cp_resume+0x0/0xbc [radeon]
		// [<c049b1c0>] ? vfs_ioctl+0x50/0x69
		// [<c049b414>] ? do_vfs_ioctl+0x23b/0x247
		// [<c0460a56>] ? audit_syscall_entry+0xf9/0x123
		// [<c049b460>] ? sys_ioctl+0x40/0x5c
		// [<c0403c76>] ? syscall_call+0x7/0xb

		/* An algorithm proposed by Donald E. Knuth in The Art Of Computer
		 * Programming Volume 3, under the topic of sorting and search
		 * chapter 6.4.
		 */
		hash = ((hash << 5) ^ (hash >> 27)) ^ c;
	}
	return hash;
}

std::string CAnalyzerKerneloops::GetLocalUUID(const char *pDebugDumpDir)
{
	log(_("Getting local universal unique identification"));

	std::string oops;
	{
		CDebugDump dd;
		dd.Open(pDebugDumpDir);
		dd.LoadText(FILENAME_BACKTRACE, oops);
	}

	unsigned hash = hash_oops_str(oops.c_str());
	hash &= 0x7FFFFFFF;

	return to_string(hash);
}

std::string CAnalyzerKerneloops::GetGlobalUUID(const char *pDebugDumpDir)
{
	return GetLocalUUID(pDebugDumpDir);
}

PLUGIN_INFO(ANALYZER,
            CAnalyzerKerneloops,
            "Kerneloops",
            "0.0.2",
            "Analyzes kernel oopses",
            "anton@redhat.com",
            "https://people.redhat.com/aarapov",
            "");