linux/tools/perf/util/util.c
Milos Vyletel d7c72606d9 perf tools: Avoid possible race condition in copyfile()
Use unique temporary files when copying to buildid dir to prevent races
in case multiple instances are trying to copy same file. This is done by

- creating template in form <path>/.<filename>.XXXXXX where the suffix is
  used by mkstemp() to create unique file
- change file mode
- copy content
- if successful link temp file to target file
- unlink temp file

At this point the only file left at target path should be the desired
one either created by us or other instance if we raced. This should also
prevent not yet fully copied files to be visible to to other perf
instances that could try to parse them.

On top of that slow_copyfile no longer needs to deal with file mode when
creating file since temporary file is already created and mode is set.

Succesfully tested by myself by running perf record, archive and reading
the data on other system and by running perf buildid-cache on perf
binary itself. I also did revert fix from 0635b0f that to exposes
previously fixed race with EEXIST and recreator test passed sucessfully.

Signed-off-by: Milos Vyletel <milos@redhat.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1433775018-19868-1-git-send-email-milos@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2015-06-10 11:51:24 -03:00

697 lines
12 KiB
C

#include "../perf.h"
#include "util.h"
#include "debug.h"
#include <api/fs/fs.h>
#include <sys/mman.h>
#ifdef HAVE_BACKTRACE_SUPPORT
#include <execinfo.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#include <byteswap.h>
#include <linux/kernel.h>
#include <unistd.h>
#include "callchain.h"
struct callchain_param callchain_param = {
.mode = CHAIN_GRAPH_REL,
.min_percent = 0.5,
.order = ORDER_CALLEE,
.key = CCKEY_FUNCTION
};
/*
* XXX We need to find a better place for these things...
*/
unsigned int page_size;
int cacheline_size;
bool test_attr__enabled;
bool perf_host = true;
bool perf_guest = false;
char tracing_events_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing/events";
void event_attr_init(struct perf_event_attr *attr)
{
if (!perf_host)
attr->exclude_host = 1;
if (!perf_guest)
attr->exclude_guest = 1;
/* to capture ABI version */
attr->size = sizeof(*attr);
}
int mkdir_p(char *path, mode_t mode)
{
struct stat st;
int err;
char *d = path;
if (*d != '/')
return -1;
if (stat(path, &st) == 0)
return 0;
while (*++d == '/');
while ((d = strchr(d, '/'))) {
*d = '\0';
err = stat(path, &st) && mkdir(path, mode);
*d++ = '/';
if (err)
return -1;
while (*d == '/')
++d;
}
return (stat(path, &st) && mkdir(path, mode)) ? -1 : 0;
}
int rm_rf(char *path)
{
DIR *dir;
int ret = 0;
struct dirent *d;
char namebuf[PATH_MAX];
dir = opendir(path);
if (dir == NULL)
return 0;
while ((d = readdir(dir)) != NULL && !ret) {
struct stat statbuf;
if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
continue;
scnprintf(namebuf, sizeof(namebuf), "%s/%s",
path, d->d_name);
ret = stat(namebuf, &statbuf);
if (ret < 0) {
pr_debug("stat failed: %s\n", namebuf);
break;
}
if (S_ISREG(statbuf.st_mode))
ret = unlink(namebuf);
else if (S_ISDIR(statbuf.st_mode))
ret = rm_rf(namebuf);
else {
pr_debug("unknown file: %s\n", namebuf);
ret = -1;
}
}
closedir(dir);
if (ret < 0)
return ret;
return rmdir(path);
}
static int slow_copyfile(const char *from, const char *to)
{
int err = -1;
char *line = NULL;
size_t n;
FILE *from_fp = fopen(from, "r"), *to_fp;
if (from_fp == NULL)
goto out;
to_fp = fopen(to, "w");
if (to_fp == NULL)
goto out_fclose_from;
while (getline(&line, &n, from_fp) > 0)
if (fputs(line, to_fp) == EOF)
goto out_fclose_to;
err = 0;
out_fclose_to:
fclose(to_fp);
free(line);
out_fclose_from:
fclose(from_fp);
out:
return err;
}
int copyfile_offset(int ifd, loff_t off_in, int ofd, loff_t off_out, u64 size)
{
void *ptr;
loff_t pgoff;
pgoff = off_in & ~(page_size - 1);
off_in -= pgoff;
ptr = mmap(NULL, off_in + size, PROT_READ, MAP_PRIVATE, ifd, pgoff);
if (ptr == MAP_FAILED)
return -1;
while (size) {
ssize_t ret = pwrite(ofd, ptr + off_in, size, off_out);
if (ret < 0 && errno == EINTR)
continue;
if (ret <= 0)
break;
size -= ret;
off_in += ret;
off_out -= ret;
}
munmap(ptr, off_in + size);
return size ? -1 : 0;
}
int copyfile_mode(const char *from, const char *to, mode_t mode)
{
int fromfd, tofd;
struct stat st;
int err = -1;
char *tmp = NULL, *ptr = NULL;
if (stat(from, &st))
goto out;
/* extra 'x' at the end is to reserve space for '.' */
if (asprintf(&tmp, "%s.XXXXXXx", to) < 0) {
tmp = NULL;
goto out;
}
ptr = strrchr(tmp, '/');
if (!ptr)
goto out;
ptr = memmove(ptr + 1, ptr, strlen(ptr) - 1);
*ptr = '.';
tofd = mkstemp(tmp);
if (tofd < 0)
goto out;
if (fchmod(tofd, mode))
goto out_close_to;
if (st.st_size == 0) { /* /proc? do it slowly... */
err = slow_copyfile(from, tmp);
goto out_close_to;
}
fromfd = open(from, O_RDONLY);
if (fromfd < 0)
goto out_close_to;
err = copyfile_offset(fromfd, 0, tofd, 0, st.st_size);
close(fromfd);
out_close_to:
close(tofd);
if (!err)
err = link(tmp, to);
unlink(tmp);
out:
free(tmp);
return err;
}
int copyfile(const char *from, const char *to)
{
return copyfile_mode(from, to, 0755);
}
unsigned long convert_unit(unsigned long value, char *unit)
{
*unit = ' ';
if (value > 1000) {
value /= 1000;
*unit = 'K';
}
if (value > 1000) {
value /= 1000;
*unit = 'M';
}
if (value > 1000) {
value /= 1000;
*unit = 'G';
}
return value;
}
static ssize_t ion(bool is_read, int fd, void *buf, size_t n)
{
void *buf_start = buf;
size_t left = n;
while (left) {
ssize_t ret = is_read ? read(fd, buf, left) :
write(fd, buf, left);
if (ret < 0 && errno == EINTR)
continue;
if (ret <= 0)
return ret;
left -= ret;
buf += ret;
}
BUG_ON((size_t)(buf - buf_start) != n);
return n;
}
/*
* Read exactly 'n' bytes or return an error.
*/
ssize_t readn(int fd, void *buf, size_t n)
{
return ion(true, fd, buf, n);
}
/*
* Write exactly 'n' bytes or return an error.
*/
ssize_t writen(int fd, void *buf, size_t n)
{
return ion(false, fd, buf, n);
}
size_t hex_width(u64 v)
{
size_t n = 1;
while ((v >>= 4))
++n;
return n;
}
static int hex(char ch)
{
if ((ch >= '0') && (ch <= '9'))
return ch - '0';
if ((ch >= 'a') && (ch <= 'f'))
return ch - 'a' + 10;
if ((ch >= 'A') && (ch <= 'F'))
return ch - 'A' + 10;
return -1;
}
/*
* While we find nice hex chars, build a long_val.
* Return number of chars processed.
*/
int hex2u64(const char *ptr, u64 *long_val)
{
const char *p = ptr;
*long_val = 0;
while (*p) {
const int hex_val = hex(*p);
if (hex_val < 0)
break;
*long_val = (*long_val << 4) | hex_val;
p++;
}
return p - ptr;
}
/* Obtain a backtrace and print it to stdout. */
#ifdef HAVE_BACKTRACE_SUPPORT
void dump_stack(void)
{
void *array[16];
size_t size = backtrace(array, ARRAY_SIZE(array));
char **strings = backtrace_symbols(array, size);
size_t i;
printf("Obtained %zd stack frames.\n", size);
for (i = 0; i < size; i++)
printf("%s\n", strings[i]);
free(strings);
}
#else
void dump_stack(void) {}
#endif
void sighandler_dump_stack(int sig)
{
psignal(sig, "perf");
dump_stack();
exit(sig);
}
void get_term_dimensions(struct winsize *ws)
{
char *s = getenv("LINES");
if (s != NULL) {
ws->ws_row = atoi(s);
s = getenv("COLUMNS");
if (s != NULL) {
ws->ws_col = atoi(s);
if (ws->ws_row && ws->ws_col)
return;
}
}
#ifdef TIOCGWINSZ
if (ioctl(1, TIOCGWINSZ, ws) == 0 &&
ws->ws_row && ws->ws_col)
return;
#endif
ws->ws_row = 25;
ws->ws_col = 80;
}
void set_term_quiet_input(struct termios *old)
{
struct termios tc;
tcgetattr(0, old);
tc = *old;
tc.c_lflag &= ~(ICANON | ECHO);
tc.c_cc[VMIN] = 0;
tc.c_cc[VTIME] = 0;
tcsetattr(0, TCSANOW, &tc);
}
static void set_tracing_events_path(const char *tracing, const char *mountpoint)
{
snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
mountpoint, tracing, "events");
}
static const char *__perf_tracefs_mount(const char *mountpoint)
{
const char *mnt;
mnt = tracefs_mount(mountpoint);
if (!mnt)
return NULL;
set_tracing_events_path("", mnt);
return mnt;
}
static const char *__perf_debugfs_mount(const char *mountpoint)
{
const char *mnt;
mnt = debugfs_mount(mountpoint);
if (!mnt)
return NULL;
set_tracing_events_path("tracing/", mnt);
return mnt;
}
const char *perf_debugfs_mount(const char *mountpoint)
{
const char *mnt;
mnt = __perf_tracefs_mount(mountpoint);
if (mnt)
return mnt;
mnt = __perf_debugfs_mount(mountpoint);
return mnt;
}
void perf_debugfs_set_path(const char *mntpt)
{
snprintf(debugfs_mountpoint, strlen(debugfs_mountpoint), "%s", mntpt);
set_tracing_events_path("tracing/", mntpt);
}
static const char *find_tracefs(void)
{
const char *path = __perf_tracefs_mount(NULL);
return path;
}
static const char *find_debugfs(void)
{
const char *path = __perf_debugfs_mount(NULL);
if (!path)
fprintf(stderr, "Your kernel does not support the debugfs filesystem");
return path;
}
/*
* Finds the path to the debugfs/tracing
* Allocates the string and stores it.
*/
const char *find_tracing_dir(void)
{
const char *tracing_dir = "";
static char *tracing;
static int tracing_found;
const char *debugfs;
if (tracing_found)
return tracing;
debugfs = find_tracefs();
if (!debugfs) {
tracing_dir = "/tracing";
debugfs = find_debugfs();
if (!debugfs)
return NULL;
}
if (asprintf(&tracing, "%s%s", debugfs, tracing_dir) < 0)
return NULL;
tracing_found = 1;
return tracing;
}
char *get_tracing_file(const char *name)
{
const char *tracing;
char *file;
tracing = find_tracing_dir();
if (!tracing)
return NULL;
if (asprintf(&file, "%s/%s", tracing, name) < 0)
return NULL;
return file;
}
void put_tracing_file(char *file)
{
free(file);
}
int parse_nsec_time(const char *str, u64 *ptime)
{
u64 time_sec, time_nsec;
char *end;
time_sec = strtoul(str, &end, 10);
if (*end != '.' && *end != '\0')
return -1;
if (*end == '.') {
int i;
char nsec_buf[10];
if (strlen(++end) > 9)
return -1;
strncpy(nsec_buf, end, 9);
nsec_buf[9] = '\0';
/* make it nsec precision */
for (i = strlen(nsec_buf); i < 9; i++)
nsec_buf[i] = '0';
time_nsec = strtoul(nsec_buf, &end, 10);
if (*end != '\0')
return -1;
} else
time_nsec = 0;
*ptime = time_sec * NSEC_PER_SEC + time_nsec;
return 0;
}
unsigned long parse_tag_value(const char *str, struct parse_tag *tags)
{
struct parse_tag *i = tags;
while (i->tag) {
char *s;
s = strchr(str, i->tag);
if (s) {
unsigned long int value;
char *endptr;
value = strtoul(str, &endptr, 10);
if (s != endptr)
break;
if (value > ULONG_MAX / i->mult)
break;
value *= i->mult;
return value;
}
i++;
}
return (unsigned long) -1;
}
int filename__read_str(const char *filename, char **buf, size_t *sizep)
{
size_t size = 0, alloc_size = 0;
void *bf = NULL, *nbf;
int fd, n, err = 0;
char sbuf[STRERR_BUFSIZE];
fd = open(filename, O_RDONLY);
if (fd < 0)
return -errno;
do {
if (size == alloc_size) {
alloc_size += BUFSIZ;
nbf = realloc(bf, alloc_size);
if (!nbf) {
err = -ENOMEM;
break;
}
bf = nbf;
}
n = read(fd, bf + size, alloc_size - size);
if (n < 0) {
if (size) {
pr_warning("read failed %d: %s\n", errno,
strerror_r(errno, sbuf, sizeof(sbuf)));
err = 0;
} else
err = -errno;
break;
}
size += n;
} while (n > 0);
if (!err) {
*sizep = size;
*buf = bf;
} else
free(bf);
close(fd);
return err;
}
const char *get_filename_for_perf_kvm(void)
{
const char *filename;
if (perf_host && !perf_guest)
filename = strdup("perf.data.host");
else if (!perf_host && perf_guest)
filename = strdup("perf.data.guest");
else
filename = strdup("perf.data.kvm");
return filename;
}
int perf_event_paranoid(void)
{
int value;
if (sysctl__read_int("kernel/perf_event_paranoid", &value))
return INT_MAX;
return value;
}
void mem_bswap_32(void *src, int byte_size)
{
u32 *m = src;
while (byte_size > 0) {
*m = bswap_32(*m);
byte_size -= sizeof(u32);
++m;
}
}
void mem_bswap_64(void *src, int byte_size)
{
u64 *m = src;
while (byte_size > 0) {
*m = bswap_64(*m);
byte_size -= sizeof(u64);
++m;
}
}
bool find_process(const char *name)
{
size_t len = strlen(name);
DIR *dir;
struct dirent *d;
int ret = -1;
dir = opendir(procfs__mountpoint());
if (!dir)
return -1;
/* Walk through the directory. */
while (ret && (d = readdir(dir)) != NULL) {
char path[PATH_MAX];
char *data;
size_t size;
if ((d->d_type != DT_DIR) ||
!strcmp(".", d->d_name) ||
!strcmp("..", d->d_name))
continue;
scnprintf(path, sizeof(path), "%s/%s/comm",
procfs__mountpoint(), d->d_name);
if (filename__read_str(path, &data, &size))
continue;
ret = strncmp(name, data, len);
free(data);
}
closedir(dir);
return ret ? false : true;
}