sysprof/binfile.c

/* MemProf -- memory profiler and leak detector
 * Copyright 1999, 2000, 2001, Red Hat, Inc.
 * Copyright 2002, Kristian Rietveld
 *
 * Sysprof -- Sampling, systemwide CPU profiler
 * Copyright 2004, 2005, 2006, 2007, Soeren Sandmann
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/* Most interesting code in this file is lifted from bfdutils.c
 * and process.c from Memprof,
 */
#include "config.h"

#include <glib.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdint.h>

#include "binfile.h"
#include "elfparser.h"
#include "util.h"

struct bin_file_t
{
    int		ref_count;
    
    GList *	elf_files;
    
    char *	filename;	
    
    char *	undefined_name;
    
    gulong	text_offset;
    
    gboolean	inode_check;
    ino_t	inode;
};

static ino_t
read_inode (const char *filename)
{
    struct stat statbuf;
    
    if (strcmp (filename, "[vdso]") == 0)
	return (ino_t)0;
    
    if (stat (filename, &statbuf) < 0)
	return (ino_t)-1;
    
    return statbuf.st_ino;
}

static gboolean
already_warned (const char *name)
{
    static GPtrArray *warnings;
    int i;
    
    if (!warnings)
	warnings = g_ptr_array_new ();
    
    for (i = 0; i < warnings->len; ++i)
    {
	if (strcmp (warnings->pdata[i], name) == 0)
	    return TRUE;
    }
    
    g_ptr_array_add (warnings, g_strdup (name));
    
    return FALSE;
}

static const char *const debug_file_directory = DEBUGDIR;

static ElfParser *
get_build_id_file (ElfParser *elf)
{
    const char *build_id;
    GList *tries = NULL, *list;
    char *init, *rest;
    ElfParser *result = NULL;
    char *tmp;
    
    build_id = elf_parser_get_build_id (elf);
    
    if (!build_id)
	return NULL;
    
    if (strlen (build_id) < 4)
	return NULL;
    
    init = g_strndup (build_id, 2);
    rest = g_strdup_printf ("%s%s", build_id + 2, ".debug");
    
    tmp = g_build_filename (
	"/usr", "lib", "debug", ".build-id", init, rest, NULL);
    tries = g_list_append (tries, tmp);
    
    tmp = g_build_filename (
	debug_file_directory, ".build-id", init, rest, NULL);
    tries = g_list_append (tries, tmp);
    
    for (list = tries; list != NULL; list = list->next)
    {
	char *name = list->data;
	ElfParser *parser = elf_parser_new (name, NULL);
	
	if (parser)
	{
	    const char *file_id = elf_parser_get_build_id (parser);
	    
	    if (file_id && strcmp (build_id, file_id) == 0)
	    {
		result = parser;
		break;
	    }
	    
	    elf_parser_free (parser);
	}
    }
    
    g_list_foreach (tries, (GFunc)g_free, NULL);
    g_list_free (tries);
    
    g_free (init);
    g_free (rest);
    
    return result;
}

static ElfParser *
get_debuglink_file (ElfParser   *elf,
		    const char  *filename,
		    char       **new_name)
{
#define N_TRIES 4
    const char *basename;
    char *dir;
    guint32 crc32;
    GList *tries = NULL, *list;
    ElfParser *result = NULL;
    const char *build_id;
    
    if (!elf)
	return NULL;
    
    basename = elf_parser_get_debug_link (elf, &crc32);

    build_id = elf_parser_get_build_id (elf);
    
#if 0
    g_print ("   debug link for %s is %s\n", filename, basename);
#endif
    
    if (!basename)
	return NULL;
    
    dir = g_path_get_dirname (filename);
    
    tries = g_list_append (tries, g_build_filename (dir, basename, NULL));
    tries = g_list_append (tries, g_build_filename (dir, ".debug", basename, NULL));
    tries = g_list_append (tries, g_build_filename ("/usr", "lib", "debug", dir, basename, NULL));
    tries = g_list_append (tries, g_build_filename (debug_file_directory, dir, basename, NULL));
    
    for (list = tries; list != NULL; list = list->next)
    {
	const char *name = list->data;
	ElfParser *parser = elf_parser_new (name, NULL);
	guint32 file_crc;
	const char *file_build_id;
	
	if (parser)
	{
	    /* If both files have build ids, and they don't match,
	     * there is no point computing a CRC32 that we know
	     * will fail
	     */
	    file_build_id = elf_parser_get_build_id (parser);
	    if (build_id && file_build_id && strcmp (build_id, file_build_id) != 0)
		goto skip;

	    file_crc = elf_parser_get_crc32 (parser);
	    
	    if (file_crc == crc32)
	    {
		result = parser;
		*new_name = g_strdup (name);
		break;
	    }
	    else
	    {
		if (!already_warned (name))
		{
		    g_print ("warning: %s has wrong crc %x, %s has crc %x)\n",
			     name, file_crc, filename, crc32);
		}
	    }

	skip:
	    elf_parser_free (parser);
	}
    }
    
    g_free (dir);
    
    g_list_foreach (tries, (GFunc)g_free, NULL);
    g_list_free (tries);
    
    return result;
}

static GList *
get_debug_binaries (GList      *files,
		    ElfParser  *elf,
		    const char *filename)
{
    ElfParser *build_id_file;
    GHashTable *seen_names;
    GList *free_us = NULL;
    
    build_id_file = get_build_id_file (elf);
    
    if (build_id_file)
	return g_list_prepend (files, build_id_file);
    
    /* .gnu_debuglink is actually a chain of debuglinks, and
     * there have been real-world cases where following it was
     * necessary to get useful debug information.
     */
    seen_names = g_hash_table_new (g_str_hash, g_str_equal);
    
    while (elf)
    {
	char *debug_name;
	
	if (g_hash_table_lookup (seen_names, filename))
	    break;
	
	g_hash_table_insert (seen_names, (char *)filename, (char *)filename);
	
	elf = get_debuglink_file (elf, filename, &debug_name);
	
	if (elf)
	{
	    files = g_list_prepend (files, elf);
	    free_us = g_list_prepend (free_us, debug_name);
	    filename = debug_name;
	}
    }
    
    g_list_foreach (free_us, (GFunc)g_free, NULL);
    g_list_free (free_us);
    
    g_hash_table_destroy (seen_names);
    
    return files;
}

static char **
get_lines (const char *format, pid_t pid)
{
    char *filename = g_strdup_printf (format, pid);
    char **result = NULL;
    char *contents;
    
    if (g_file_get_contents (filename, &contents, NULL, NULL))
    {
        result = g_strsplit (contents, "\n", -1);
	
        g_free (contents);
    }
    
    g_free (filename);
    
    return result;
}

static const uint8_t *
get_vdso_bytes (size_t *length)
{
    static const uint8_t *bytes = NULL;
    static size_t n_bytes = 0;    
    static gboolean has_data;
    
    if (!has_data)
    {
	char **lines = get_lines ("/proc/%d/maps", getpid());
	int i;
	
	for (i = 0; lines[i] != NULL; ++i)
	{
	    char file[256];
	    gulong start;
	    gulong end;
	    int count = sscanf (
		lines[i], "%lx-%lx %*15s %*x %*x:%*x %*u %255s", 
		&start, &end, file);
	    
	    if (count == 3 && strcmp (file, "[vdso]") == 0)
	    {
		n_bytes = end - start;
		
		/* Dup the memory here so that valgrind will only
		 * report one 1 byte invalid read instead of
		 * a ton when the elf parser scans the vdso
		 *
		 * The reason we get a spurious invalid read from
		 * valgrind is that we are getting the address directly
		 * from /proc/maps, and valgrind knows that its mmap()
		 * wrapper never returned that address. But since it
		 * is a legal mapping, it is legal to read it.
		 */
		bytes = g_memdup ((uint8_t *)start, n_bytes);
		
		has_data = TRUE;
	    }
	}
    }
    
    if (length)
	*length = n_bytes;
    
    return bytes;
}

bin_file_t *
bin_file_new (const char *filename)
{
    ElfParser *elf = NULL;
    bin_file_t *bf;
    
    bf = g_new0 (bin_file_t, 1);
    
    bf->inode_check = FALSE;
    bf->filename = g_strdup (filename);
    bf->undefined_name = g_strdup_printf ("In file %s", filename);
    bf->ref_count = 1;
    bf->elf_files = NULL;
    
    if (strcmp (filename, "[vdso]") == 0)
    {
	const guint8 *vdso_bytes;
	gsize length;
	
	vdso_bytes = get_vdso_bytes (&length);
	
	if (vdso_bytes)
	    elf = elf_parser_new_from_data (vdso_bytes, length);
    }
    else
    {
	elf = elf_parser_new (filename, NULL);
    }
    
    if (elf)
    {
	/* We need the text offset of the actual binary, not the
	 * (potential) debug binaries
	 */
	bf->text_offset = elf_parser_get_text_offset (elf);
	
	bf->elf_files = get_debug_binaries (bf->elf_files, elf, filename);
	bf->elf_files = g_list_append (bf->elf_files, elf);
	
	bf->inode = read_inode (filename);
    }
    
    return bf;
}

void
bin_file_free (bin_file_t *bin_file)
{
    if (--bin_file->ref_count == 0)
    {
	g_list_foreach (bin_file->elf_files, (GFunc)elf_parser_free, NULL);
	g_list_free (bin_file->elf_files);
	
	g_free (bin_file->filename);
	g_free (bin_file->undefined_name);
	g_free (bin_file);
    }
}

const bin_symbol_t *
bin_file_lookup_symbol (bin_file_t    *bin_file,
			gulong      address)
{
    GList *list;
    
#if 0
    g_print ("-=-=-=- \n");
    
    g_print ("bin file lookup lookup %d\n", address);
#endif
    
    address -= bin_file->text_offset;
    
#if 0
    g_print ("lookup %d in %s\n", address, bin_file->filename);
#endif
    
    for (list = bin_file->elf_files; list != NULL; list = list->next)
    {
	ElfParser *elf = list->data;
	const ElfSym *sym = elf_parser_lookup_symbol (elf, address);
	
	if (sym)
	{
#if 0
	    g_print ("found  %lx => %s\n", address,
		     bin_symbol_get_name (bin_file, sym));
#endif
	    return (const bin_symbol_t *)sym;
	}
    }
    
#if 0
    g_print ("%lx undefined in %s (textoffset %x)\n",
	     address + bin_file->text_offset,
	     bin_file->filename,
	     bin_file->text_offset);
#endif
    
    return (const bin_symbol_t *)bin_file->undefined_name;
}

gboolean
bin_file_check_inode (bin_file_t *bin_file,
		      ino_t       inode)
{
    if (bin_file->inode == inode)
	return TRUE;
    
    if (!bin_file->elf_files)
	return FALSE;
    
    if (!bin_file->inode_check)
    {
	g_print ("warning: Inode mismatch for %s (disk: "FMT64", memory: "FMT64")\n",
		 bin_file->filename,
		 (guint64)bin_file->inode, (guint64)inode);
	
	bin_file->inode_check = TRUE;
    }
    
    return FALSE;
}

static const ElfSym *
get_elf_sym (bin_file_t *file,
	     const bin_symbol_t *symbol,
	     ElfParser **elf_ret)
{
    GList *list;
    
    for (list = file->elf_files; list != NULL; list = list->next)
    {
	const ElfSym *sym = (const ElfSym *)symbol;
	ElfParser *elf = list->data;
	
	if (elf_parser_owns_symbol (elf, sym))
	{
	    *elf_ret = elf;
	    return sym;
	}
    }
    
    g_critical ("Internal error: unrecognized symbol pointer");
    
    *elf_ret = NULL;
    return NULL;
}

const char *
bin_symbol_get_name (bin_file_t *file,
		     const bin_symbol_t *symbol)
{
    if (file->undefined_name == (char *)symbol)
    {
	return file->undefined_name;
    }
    else
    {
	ElfParser *elf;
	const ElfSym *sym;
	
	sym = get_elf_sym (file, symbol, &elf);
	
	return elf_parser_get_sym_name (elf, sym);
    }
}

gulong
bin_symbol_get_address (bin_file_t      *file,
			const bin_symbol_t *symbol)
{
    if (file->undefined_name == (char *)symbol)
    {
	return 0x0;
    }
    else
    {
	ElfParser *elf;
	const ElfSym *sym;
	
	sym = get_elf_sym (file, symbol, &elf);
	
	return elf_parser_get_sym_address (elf, sym);
    }
}