/*
   * build-id.c
   *
   * build-id support
   *
   * Copyright (C) 2009, 2010 Red Hat Inc.
   * Copyright (C) 2009, 2010 Arnaldo Carvalho de Melo <acme@redhat.com>
   */

  #include "util.h"

  #include <dirent.h>

  #include <errno.h>

  #include <stdio.h>

  #include <sys/stat.h>
  #include <sys/types.h>

  #include "build-id.h"
  #include "event.h"
  #include "symbol.h"

  #include "thread.h"

  #include <linux/kernel.h>

  #include "debug.h"

  #include "session.h"

  #include "tool.h"

  #include "header.h"
  #include "vdso.h"

  #include "path.h"

  #include "probe-file.h"

  #include "strlist.h"

  #include "sane_ctype.h"

  
  static bool no_buildid_cache;

  int build_id__mark_dso_hit(struct perf_tool *tool __maybe_unused,
  			   union perf_event *event,

  			   struct perf_sample *sample,

  			   struct perf_evsel *evsel __maybe_unused,
  			   struct machine *machine)

  {
  	struct addr_location al;

  	struct thread *thread = machine__findnew_thread(machine, sample->pid,

  							sample->tid);

  
  	if (thread == NULL) {
  		pr_err("problem processing %d event, skipping it.
  ",
  			event->header.type);
  		return -1;
  	}

  	thread__find_addr_map(thread, sample->cpumode, MAP__FUNCTION, sample->ip, &al);

  
  	if (al.map != NULL)
  		al.map->dso->hit = 1;

  	thread__put(thread);

  	return 0;
  }

  static int perf_event__exit_del_thread(struct perf_tool *tool __maybe_unused,

  				       union perf_event *event,

  				       struct perf_sample *sample
  				       __maybe_unused,

  				       struct machine *machine)

  {

  	struct thread *thread = machine__findnew_thread(machine,
  							event->fork.pid,
  							event->fork.tid);

  	dump_printf("(%d:%d):(%d:%d)
  ", event->fork.pid, event->fork.tid,
  		    event->fork.ppid, event->fork.ptid);

  	if (thread) {

  		machine__remove_thread(machine, thread);

  		thread__put(thread);
  	}

  
  	return 0;
  }

  struct perf_tool build_id__mark_dso_hit_ops = {

  	.sample	= build_id__mark_dso_hit,

  	.mmap	= perf_event__process_mmap,

  	.mmap2	= perf_event__process_mmap2,

  	.fork	= perf_event__process_fork,

  	.exit	= perf_event__exit_del_thread,

  	.attr		 = perf_event__process_attr,
  	.build_id	 = perf_event__process_build_id,

  	.ordered_events	 = true,

  };

  int build_id__sprintf(const u8 *build_id, int len, char *bf)
  {
  	char *bid = bf;
  	const u8 *raw = build_id;
  	int i;
  
  	for (i = 0; i < len; ++i) {
  		sprintf(bid, "%02x", *raw);
  		++raw;
  		bid += 2;
  	}

  	return (bid - bf) + 1;

  }

  int sysfs__sprintf_build_id(const char *root_dir, char *sbuild_id)
  {
  	char notes[PATH_MAX];
  	u8 build_id[BUILD_ID_SIZE];
  	int ret;
  
  	if (!root_dir)
  		root_dir = "";
  
  	scnprintf(notes, sizeof(notes), "%s/sys/kernel/notes", root_dir);
  
  	ret = sysfs__read_build_id(notes, build_id, sizeof(build_id));
  	if (ret < 0)
  		return ret;
  
  	return build_id__sprintf(build_id, sizeof(build_id), sbuild_id);
  }
  
  int filename__sprintf_build_id(const char *pathname, char *sbuild_id)
  {
  	u8 build_id[BUILD_ID_SIZE];
  	int ret;
  
  	ret = filename__read_build_id(pathname, build_id, sizeof(build_id));
  	if (ret < 0)
  		return ret;
  	else if (ret != sizeof(build_id))
  		return -EINVAL;
  
  	return build_id__sprintf(build_id, sizeof(build_id), sbuild_id);
  }

  /* asnprintf consolidates asprintf and snprintf */
  static int asnprintf(char **strp, size_t size, const char *fmt, ...)
  {
  	va_list ap;
  	int ret;
  
  	if (!strp)
  		return -EINVAL;
  
  	va_start(ap, fmt);
  	if (*strp)
  		ret = vsnprintf(*strp, size, fmt, ap);
  	else
  		ret = vasprintf(strp, fmt, ap);
  	va_end(ap);
  
  	return ret;
  }

  char *build_id_cache__kallsyms_path(const char *sbuild_id, char *bf,
  				    size_t size)
  {

  	bool retry_old = true;

  	snprintf(bf, size, "%s/%s/%s/kallsyms",
  		 buildid_dir, DSO__NAME_KALLSYMS, sbuild_id);

  retry:
  	if (!access(bf, F_OK))
  		return bf;

  	if (retry_old) {
  		/* Try old style kallsyms cache */

  		snprintf(bf, size, "%s/%s/%s",
  			 buildid_dir, DSO__NAME_KALLSYMS, sbuild_id);

  		retry_old = false;
  		goto retry;
  	}
  
  	return NULL;
  }

  char *build_id_cache__linkname(const char *sbuild_id, char *bf, size_t size)

  {
  	char *tmp = bf;
  	int ret = asnprintf(&bf, size, "%s/.build-id/%.2s/%s", buildid_dir,
  			    sbuild_id, sbuild_id + 2);
  	if (ret < 0 || (tmp && size < (unsigned int)ret))
  		return NULL;
  	return bf;
  }

  char *build_id_cache__origname(const char *sbuild_id)
  {
  	char *linkname;
  	char buf[PATH_MAX];
  	char *ret = NULL, *p;
  	size_t offs = 5;	/* == strlen("../..") */

  	ssize_t len;

  
  	linkname = build_id_cache__linkname(sbuild_id, NULL, 0);
  	if (!linkname)
  		return NULL;

  	len = readlink(linkname, buf, sizeof(buf) - 1);
  	if (len <= 0)

  		goto out;

  	buf[len] = '\0';

  	/* The link should be "../..<origpath>/<sbuild_id>" */
  	p = strrchr(buf, '/');	/* Cut off the "/<sbuild_id>" */
  	if (p && (p > buf + offs)) {
  		*p = '\0';
  		if (buf[offs + 1] == '[')
  			offs++;	/*
  				 * This is a DSO name, like [kernel.kallsyms].
  				 * Skip the first '/', since this is not the
  				 * cache of a regular file.
  				 */
  		ret = strdup(buf + offs);	/* Skip "../..[/]" */
  	}
  out:
  	free(linkname);
  	return ret;
  }

  /* Check if the given build_id cache is valid on current running system */
  static bool build_id_cache__valid_id(char *sbuild_id)
  {
  	char real_sbuild_id[SBUILD_ID_SIZE] = "";
  	char *pathname;
  	int ret = 0;
  	bool result = false;
  
  	pathname = build_id_cache__origname(sbuild_id);
  	if (!pathname)
  		return false;
  
  	if (!strcmp(pathname, DSO__NAME_KALLSYMS))
  		ret = sysfs__sprintf_build_id("/", real_sbuild_id);
  	else if (pathname[0] == '/')
  		ret = filename__sprintf_build_id(pathname, real_sbuild_id);
  	else
  		ret = -EINVAL;	/* Should we support other special DSO cache? */
  	if (ret >= 0)
  		result = (strcmp(sbuild_id, real_sbuild_id) == 0);
  	free(pathname);
  
  	return result;
  }

  static const char *build_id_cache__basename(bool is_kallsyms, bool is_vdso)
  {
  	return is_kallsyms ? "kallsyms" : (is_vdso ? "vdso" : "elf");
  }

  char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size)

  {

  	bool is_kallsyms = dso__is_kallsyms((struct dso *)dso);
  	bool is_vdso = dso__is_vdso((struct dso *)dso);
  	char sbuild_id[SBUILD_ID_SIZE];
  	char *linkname;
  	bool alloc = (bf == NULL);
  	int ret;

  	if (!dso->has_build_id)

  		return NULL;

  	build_id__sprintf(dso->build_id, sizeof(dso->build_id), sbuild_id);
  	linkname = build_id_cache__linkname(sbuild_id, NULL, 0);
  	if (!linkname)
  		return NULL;
  
  	/* Check if old style build_id cache */
  	if (is_regular_file(linkname))
  		ret = asnprintf(&bf, size, "%s", linkname);
  	else
  		ret = asnprintf(&bf, size, "%s/%s", linkname,
  			 build_id_cache__basename(is_kallsyms, is_vdso));
  	if (ret < 0 || (!alloc && size < (unsigned int)ret))
  		bf = NULL;
  	free(linkname);
  
  	return bf;

  }

  bool dso__build_id_is_kmod(const struct dso *dso, char *bf, size_t size)
  {

  	char *id_name = NULL, *ch;

  	struct stat sb;

  	char sbuild_id[SBUILD_ID_SIZE];
  
  	if (!dso->has_build_id)
  		goto err;

  	build_id__sprintf(dso->build_id, sizeof(dso->build_id), sbuild_id);
  	id_name = build_id_cache__linkname(sbuild_id, NULL, 0);

  	if (!id_name)
  		goto err;
  	if (access(id_name, F_OK))
  		goto err;
  	if (lstat(id_name, &sb) == -1)
  		goto err;
  	if ((size_t)sb.st_size > size - 1)
  		goto err;
  	if (readlink(id_name, bf, size - 1) < 0)
  		goto err;
  
  	bf[sb.st_size] = '\0';
  
  	/*
  	 * link should be:
  	 * ../../lib/modules/4.4.0-rc4/kernel/net/ipv4/netfilter/nf_nat_ipv4.ko/a09fe3eb3147dafa4e3b31dbd6257e4d696bdc92
  	 */
  	ch = strrchr(bf, '/');
  	if (!ch)
  		goto err;
  	if (ch - 3 < bf)
  		goto err;

  	free(id_name);

  	return strncmp(".ko", ch - 3, 3) == 0;
  err:

  	pr_err("Invalid build id: %s
  ", id_name ? :
  					 dso->long_name ? :
  					 dso->short_name ? :
  					 "[unknown]");

  	free(id_name);

  	return false;
  }

  #define dsos__for_each_with_build_id(pos, head)	\
  	list_for_each_entry(pos, head, node)	\
  		if (!pos->has_build_id)		\
  			continue;		\
  		else
  
  static int write_buildid(const char *name, size_t name_len, u8 *build_id,
  			 pid_t pid, u16 misc, int fd)
  {
  	int err;
  	struct build_id_event b;
  	size_t len;
  
  	len = name_len + 1;
  	len = PERF_ALIGN(len, NAME_ALIGN);
  
  	memset(&b, 0, sizeof(b));
  	memcpy(&b.build_id, build_id, BUILD_ID_SIZE);
  	b.pid = pid;
  	b.header.misc = misc;
  	b.header.size = sizeof(b) + len;
  
  	err = writen(fd, &b, sizeof(b));
  	if (err < 0)
  		return err;
  
  	return write_padded(fd, name, name_len + 1, len);
  }

  static int machine__write_buildid_table(struct machine *machine, int fd)

  {

  	int err = 0;

  	char nm[PATH_MAX];
  	struct dso *pos;

  	u16 kmisc = PERF_RECORD_MISC_KERNEL,
  	    umisc = PERF_RECORD_MISC_USER;
  
  	if (!machine__is_host(machine)) {
  		kmisc = PERF_RECORD_MISC_GUEST_KERNEL;
  		umisc = PERF_RECORD_MISC_GUEST_USER;
  	}

  	dsos__for_each_with_build_id(pos, &machine->dsos.head) {

  		const char *name;
  		size_t name_len;

  		bool in_kernel = false;

  		if (!pos->hit && !dso__is_vdso(pos))

  			continue;
  
  		if (dso__is_vdso(pos)) {
  			name = pos->short_name;

  			name_len = pos->short_name_len;

  		} else if (dso__is_kcore(pos)) {
  			machine__mmap_name(machine, nm, sizeof(nm));
  			name = nm;

  			name_len = strlen(nm);

  		} else {
  			name = pos->long_name;

  			name_len = pos->long_name_len;

  		}

  		in_kernel = pos->kernel ||
  				is_kernel_module(name,
  					PERF_RECORD_MISC_CPUMODE_UNKNOWN);

  		err = write_buildid(name, name_len, pos->build_id, machine->pid,

  				    in_kernel ? kmisc : umisc, fd);

  		if (err)

  			break;

  	}

  	return err;
  }
  
  int perf_session__write_buildid_table(struct perf_session *session, int fd)
  {
  	struct rb_node *nd;
  	int err = machine__write_buildid_table(&session->machines.host, fd);
  
  	if (err)
  		return err;
  
  	for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
  		struct machine *pos = rb_entry(nd, struct machine, rb_node);
  		err = machine__write_buildid_table(pos, fd);
  		if (err)
  			break;
  	}
  	return err;
  }
  
  static int __dsos__hit_all(struct list_head *head)
  {
  	struct dso *pos;
  
  	list_for_each_entry(pos, head, node)
  		pos->hit = true;
  
  	return 0;
  }
  
  static int machine__hit_all_dsos(struct machine *machine)
  {

  	return __dsos__hit_all(&machine->dsos.head);

  }
  
  int dsos__hit_all(struct perf_session *session)
  {
  	struct rb_node *nd;
  	int err;
  
  	err = machine__hit_all_dsos(&session->machines.host);
  	if (err)
  		return err;
  
  	for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
  		struct machine *pos = rb_entry(nd, struct machine, rb_node);
  
  		err = machine__hit_all_dsos(pos);
  		if (err)
  			return err;
  	}
  
  	return 0;
  }

  void disable_buildid_cache(void)
  {
  	no_buildid_cache = true;
  }

  static bool lsdir_bid_head_filter(const char *name __maybe_unused,

  				  struct dirent *d)

  {
  	return (strlen(d->d_name) == 2) &&
  		isxdigit(d->d_name[0]) && isxdigit(d->d_name[1]);
  }
  
  static bool lsdir_bid_tail_filter(const char *name __maybe_unused,

  				  struct dirent *d)

  {
  	int i = 0;
  	while (isxdigit(d->d_name[i]) && i < SBUILD_ID_SIZE - 3)
  		i++;
  	return (i == SBUILD_ID_SIZE - 3) && (d->d_name[i] == '\0');
  }

  struct strlist *build_id_cache__list_all(bool validonly)

  {
  	struct strlist *toplist, *linklist = NULL, *bidlist;
  	struct str_node *nd, *nd2;
  	char *topdir, *linkdir = NULL;
  	char sbuild_id[SBUILD_ID_SIZE];

  	/* for filename__ functions */
  	if (validonly)
  		symbol__init(NULL);

  	/* Open the top-level directory */
  	if (asprintf(&topdir, "%s/.build-id/", buildid_dir) < 0)
  		return NULL;
  
  	bidlist = strlist__new(NULL, NULL);
  	if (!bidlist)
  		goto out;
  
  	toplist = lsdir(topdir, lsdir_bid_head_filter);
  	if (!toplist) {
  		pr_debug("Error in lsdir(%s): %d
  ", topdir, errno);
  		/* If there is no buildid cache, return an empty list */
  		if (errno == ENOENT)
  			goto out;
  		goto err_out;
  	}
  
  	strlist__for_each_entry(nd, toplist) {
  		if (asprintf(&linkdir, "%s/%s", topdir, nd->s) < 0)
  			goto err_out;
  		/* Open the lower-level directory */
  		linklist = lsdir(linkdir, lsdir_bid_tail_filter);
  		if (!linklist) {
  			pr_debug("Error in lsdir(%s): %d
  ", linkdir, errno);
  			goto err_out;
  		}
  		strlist__for_each_entry(nd2, linklist) {
  			if (snprintf(sbuild_id, SBUILD_ID_SIZE, "%s%s",
  				     nd->s, nd2->s) != SBUILD_ID_SIZE - 1)
  				goto err_out;

  			if (validonly && !build_id_cache__valid_id(sbuild_id))
  				continue;

  			if (strlist__add(bidlist, sbuild_id) < 0)
  				goto err_out;
  		}
  		strlist__delete(linklist);
  		zfree(&linkdir);
  	}
  
  out_free:
  	strlist__delete(toplist);
  out:
  	free(topdir);
  
  	return bidlist;
  
  err_out:
  	strlist__delete(linklist);
  	zfree(&linkdir);
  	strlist__delete(bidlist);
  	bidlist = NULL;
  	goto out_free;
  }

  static bool str_is_build_id(const char *maybe_sbuild_id, size_t len)
  {
  	size_t i;
  
  	for (i = 0; i < len; i++) {
  		if (!isxdigit(maybe_sbuild_id[i]))
  			return false;
  	}
  	return true;
  }
  
  /* Return the valid complete build-id */
  char *build_id_cache__complement(const char *incomplete_sbuild_id)
  {
  	struct strlist *bidlist;
  	struct str_node *nd, *cand = NULL;
  	char *sbuild_id = NULL;
  	size_t len = strlen(incomplete_sbuild_id);
  
  	if (len >= SBUILD_ID_SIZE ||
  	    !str_is_build_id(incomplete_sbuild_id, len))
  		return NULL;
  
  	bidlist = build_id_cache__list_all(true);
  	if (!bidlist)
  		return NULL;
  
  	strlist__for_each_entry(nd, bidlist) {
  		if (strncmp(nd->s, incomplete_sbuild_id, len) != 0)
  			continue;
  		if (cand) {	/* Error: There are more than 2 candidates. */
  			cand = NULL;
  			break;
  		}
  		cand = nd;
  	}
  	if (cand)
  		sbuild_id = strdup(cand->s);
  	strlist__delete(bidlist);
  
  	return sbuild_id;
  }

  char *build_id_cache__cachedir(const char *sbuild_id, const char *name,
  			       bool is_kallsyms, bool is_vdso)

  {
  	char *realname = (char *)name, *filename;
  	bool slash = is_kallsyms || is_vdso;
  
  	if (!slash) {
  		realname = realpath(name, NULL);
  		if (!realname)
  			return NULL;
  	}

  	if (asprintf(&filename, "%s%s%s%s%s", buildid_dir, slash ? "/" : "",
  		     is_vdso ? DSO__NAME_VDSO : realname,
  		     sbuild_id ? "/" : "", sbuild_id ?: "") < 0)

  		filename = NULL;
  
  	if (!slash)
  		free(realname);
  
  	return filename;
  }
  
  int build_id_cache__list_build_ids(const char *pathname,
  				   struct strlist **result)
  {

  	char *dir_name;

  	int ret = 0;

  	dir_name = build_id_cache__cachedir(NULL, pathname, false, false);

  	if (!dir_name)
  		return -ENOMEM;

  	*result = lsdir(dir_name, lsdir_no_dot_filter);
  	if (!*result)

  		ret = -errno;

  	free(dir_name);

  
  	return ret;
  }

  #if defined(HAVE_LIBELF_SUPPORT) && defined(HAVE_GELF_GETNOTE_SUPPORT)

  static int build_id_cache__add_sdt_cache(const char *sbuild_id,
  					  const char *realname)
  {
  	struct probe_cache *cache;
  	int ret;
  
  	cache = probe_cache__new(sbuild_id);
  	if (!cache)
  		return -1;
  
  	ret = probe_cache__scan_sdt(cache, realname);
  	if (ret >= 0) {

  		pr_debug4("Found %d SDTs in %s
  ", ret, realname);

  		if (probe_cache__commit(cache) < 0)
  			ret = -1;
  	}
  	probe_cache__delete(cache);
  	return ret;
  }
  #else
  #define build_id_cache__add_sdt_cache(sbuild_id, realname) (0)
  #endif

  int build_id_cache__add_s(const char *sbuild_id, const char *name,
  			  bool is_kallsyms, bool is_vdso)

  {
  	const size_t size = PATH_MAX;

  	char *realname = NULL, *filename = NULL, *dir_name = NULL,

  	     *linkname = zalloc(size), *tmp;

  	int err = -1;

  	if (!is_kallsyms) {

  		realname = realpath(name, NULL);

  		if (!realname)
  			goto out_free;
  	}

  	dir_name = build_id_cache__cachedir(sbuild_id, name,
  					    is_kallsyms, is_vdso);

  	if (!dir_name)

  		goto out_free;

  	/* Remove old style build-id cache */
  	if (is_regular_file(dir_name))
  		if (unlink(dir_name))
  			goto out_free;

  	if (mkdir_p(dir_name, 0755))

  		goto out_free;

  	/* Save the allocated buildid dirname */
  	if (asprintf(&filename, "%s/%s", dir_name,
  		     build_id_cache__basename(is_kallsyms, is_vdso)) < 0) {

  		filename = NULL;
  		goto out_free;
  	}

  
  	if (access(filename, F_OK)) {
  		if (is_kallsyms) {
  			 if (copyfile("/proc/kallsyms", filename))
  				goto out_free;

  		} else if (link(realname, filename) && errno != EEXIST &&
  				copyfile(name, filename))

  			goto out_free;
  	}

  	if (!build_id_cache__linkname(sbuild_id, linkname, size))

  		goto out_free;
  	tmp = strrchr(linkname, '/');
  	*tmp = '\0';

  
  	if (access(linkname, X_OK) && mkdir_p(linkname, 0755))
  		goto out_free;

  	*tmp = '/';

  	tmp = dir_name + strlen(buildid_dir) - 5;
  	memcpy(tmp, "../..", 5);

  	if (symlink(tmp, linkname) == 0)

  		err = 0;

  
  	/* Update SDT cache : error is just warned */

  	if (realname && build_id_cache__add_sdt_cache(sbuild_id, realname) < 0)

  		pr_debug4("Failed to update/scan SDT cache for %s
  ", realname);

  out_free:
  	if (!is_kallsyms)
  		free(realname);
  	free(filename);

  	free(dir_name);

  	free(linkname);
  	return err;
  }
  
  static int build_id_cache__add_b(const u8 *build_id, size_t build_id_size,

  				 const char *name, bool is_kallsyms,
  				 bool is_vdso)

  {

  	char sbuild_id[SBUILD_ID_SIZE];

  
  	build_id__sprintf(build_id, build_id_size, sbuild_id);

  	return build_id_cache__add_s(sbuild_id, name, is_kallsyms, is_vdso);

  }

  bool build_id_cache__cached(const char *sbuild_id)
  {
  	bool ret = false;

  	char *filename = build_id_cache__linkname(sbuild_id, NULL, 0);

  
  	if (filename && !access(filename, F_OK))
  		ret = true;
  	free(filename);
  
  	return ret;
  }

  int build_id_cache__remove_s(const char *sbuild_id)

  {
  	const size_t size = PATH_MAX;
  	char *filename = zalloc(size),

  	     *linkname = zalloc(size), *tmp;

  	int err = -1;
  
  	if (filename == NULL || linkname == NULL)
  		goto out_free;

  	if (!build_id_cache__linkname(sbuild_id, linkname, size))

  		goto out_free;

  
  	if (access(linkname, F_OK))
  		goto out_free;
  
  	if (readlink(linkname, filename, size - 1) < 0)
  		goto out_free;
  
  	if (unlink(linkname))
  		goto out_free;
  
  	/*
  	 * Since the link is relative, we must make it absolute:
  	 */

  	tmp = strrchr(linkname, '/') + 1;
  	snprintf(tmp, size - (tmp - linkname), "%s", filename);

  	if (rm_rf(linkname))

  		goto out_free;
  
  	err = 0;
  out_free:
  	free(filename);
  	free(linkname);
  	return err;
  }

  static int dso__cache_build_id(struct dso *dso, struct machine *machine)

  {

  	bool is_kallsyms = dso__is_kallsyms(dso);

  	bool is_vdso = dso__is_vdso(dso);
  	const char *name = dso->long_name;
  	char nm[PATH_MAX];
  
  	if (dso__is_kcore(dso)) {
  		is_kallsyms = true;
  		machine__mmap_name(machine, nm, sizeof(nm));
  		name = nm;
  	}
  	return build_id_cache__add_b(dso->build_id, sizeof(dso->build_id), name,

  				     is_kallsyms, is_vdso);

  }
  
  static int __dsos__cache_build_ids(struct list_head *head,

  				   struct machine *machine)

  {
  	struct dso *pos;
  	int err = 0;
  
  	dsos__for_each_with_build_id(pos, head)

  		if (dso__cache_build_id(pos, machine))

  			err = -1;
  
  	return err;
  }

  static int machine__cache_build_ids(struct machine *machine)

  {

  	return __dsos__cache_build_ids(&machine->dsos.head, machine);

  }
  
  int perf_session__cache_build_ids(struct perf_session *session)
  {
  	struct rb_node *nd;
  	int ret;

  	if (no_buildid_cache)
  		return 0;

  	if (mkdir(buildid_dir, 0755) != 0 && errno != EEXIST)

  		return -1;

  	ret = machine__cache_build_ids(&session->machines.host);

  
  	for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
  		struct machine *pos = rb_entry(nd, struct machine, rb_node);

  		ret |= machine__cache_build_ids(pos);

  	}
  	return ret ? -1 : 0;
  }
  
  static bool machine__read_build_ids(struct machine *machine, bool with_hits)
  {

  	return __dsos__read_build_ids(&machine->dsos.head, with_hits);

  }
  
  bool perf_session__read_build_ids(struct perf_session *session, bool with_hits)
  {
  	struct rb_node *nd;
  	bool ret = machine__read_build_ids(&session->machines.host, with_hits);
  
  	for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
  		struct machine *pos = rb_entry(nd, struct machine, rb_node);
  		ret |= machine__read_build_ids(pos, with_hits);
  	}
  
  	return ret;
  }