NO_OPTIMIZE
static void restore_brk(VA saved_brk, VA restore_begin, VA restore_end)
{
int mtcp_sys_errno;
VA current_brk;
VA new_brk;
/* The kernel (2.6.9 anyway) has a variable mm->brk that we should restore.
* The only access we have is brk() which basically sets mm->brk to the new
* value, but also has a nasty side-effect (as far as we're concerned) of
* mmapping an anonymous section between the old value of mm->brk and the
* value being passed to brk(). It will munmap the bracketed memory if the
* value being passed is lower than the old value. But if zero, it will
* return the current mm->brk value.
*
* So we're going to restore the brk here. As long as the current mm->brk
* value is below the static restore region, we're ok because we 'know' the
* restored brk can't be in the static restore region, and we don't care if
* the kernel mmaps something or munmaps something because we're going to wipe
* it all out anyway.
*/
current_brk = mtcp_sys_brk (NULL);
if ((current_brk > restore_begin) &&
(saved_brk < restore_end)) {
MTCP_PRINTF("current_brk %p, saved_brk %p, restore_begin %p,"
" restore_end %p\n",
current_brk, saved_brk, restore_begin,
restore_end);
mtcp_abort ();
}
new_brk = mtcp_sys_brk (saved_brk);
if (new_brk == (VA)-1) {
MTCP_PRINTF("sbrk(%p): errno: %d (bad heap)\n",
saved_brk, mtcp_sys_errno );
mtcp_abort();
} else if (new_brk > current_brk) {
// Now unmap the just mapped extended heap. This is to ensure that we don't
// have overlap with the restore region.
if (mtcp_sys_munmap(current_brk, new_brk - current_brk) == -1) {
MTCP_PRINTF("***WARNING: munmap failed; errno: %d\n", mtcp_sys_errno);
}
}
if (new_brk != saved_brk) {
if (new_brk == current_brk && new_brk > saved_brk)
DPRINTF("new_brk == current_brk == %p\n; saved_break, %p,"
" is strictly smaller;\n data segment not extended.\n",
new_brk, saved_brk);
else {
if (new_brk == current_brk)
MTCP_PRINTF("error: new/current break (%p) != saved break (%p)\n",
current_brk, saved_brk);
else
MTCP_PRINTF("error: new break (%p) != current break (%p)\n",
new_brk, current_brk);
//mtcp_abort ();
}
}
}
NO_OPTIMIZE
static void restorememoryareas(RestoreInfo *rinfo_ptr)
{
int mtcp_sys_errno;
DPRINTF("Entering copy of restorememoryareas(). Will now unmap old memory"
"\n and restore memory sections from the checkpoint image.\n");
DPRINTF("DPRINTF may fail when we unmap, since strings are in rodata.\n"
"But we may be lucky if the strings have been cached by the O/S\n"
"or if compiler uses relative addressing for rodata with -fPIC\n");
if (rinfo_ptr->use_gdb) {
MTCP_PRINTF("Called with --use-gdb. A useful command is:\n"
" (gdb) info proc mapping");
if (rinfo_ptr->text_offset != -1) {
MTCP_PRINTF("Called with --text-offset 0x%x. A useful command is:\n"
"(gdb) add-symbol-file ../../bin/mtcp_restart %p\n",
rinfo_ptr->text_offset,
rinfo_ptr->restore_addr + rinfo_ptr->text_offset);
#if defined(__i386__) || defined(__x86_64__)
asm volatile ("int3"); // Do breakpoint; send SIGTRAP, caught by gdb
#else
MTCP_PRINTF("IN GDB: interrupt (^C); add-symbol-file ...; (gdb) print x=0\n");
{ int x = 1; while (x); } // Stop execution for user to type command.
#endif
}
// Used by util/readdmtcp.sh
// So, we use mtcp_printf to stdout instead of MTCP_PRINTF (diagnosis for DMTCP)
static void mtcp_simulateread(int fd, MtcpHeader *mtcpHdr)
{
int mtcp_sys_errno;
// Print miscellaneous information:
char buf[MTCP_SIGNATURE_LEN+1];
mtcp_memcpy(buf, mtcpHdr->signature, MTCP_SIGNATURE_LEN);
buf[MTCP_SIGNATURE_LEN] = '\0';
mtcp_printf("\nMTCP: %s", buf);
mtcp_printf("**** mtcp_restart (will be copied here): %p-%p\n",
mtcpHdr->restore_addr, mtcpHdr->restore_addr + mtcpHdr->restore_size);
mtcp_printf("**** DMTCP entry point (ThreadList::postRestart()): %p\n",
mtcpHdr->post_restart);
mtcp_printf("**** brk (sbrk(0)): %p\n", mtcpHdr->saved_brk);
mtcp_printf("**** vdso: %p-%p\n", mtcpHdr->vdsoStart, mtcpHdr->vdsoEnd);
mtcp_printf("**** vvar: %p-%p\n", mtcpHdr->vvarStart, mtcpHdr->vvarEnd);
Area area;
mtcp_printf("\n**** Listing ckpt image area:\n");
while(1) {
mtcp_readfile(fd, &area, sizeof area);
if (area.size == -1) break;
if ((area.properties & DMTCP_ZERO_PAGE) == 0 &&
(area.properties & DMTCP_SKIP_WRITING_TEXT_SEGMENTS) == 0) {
void *addr = mtcp_sys_mmap(0, area.size, PROT_WRITE | PROT_READ,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (addr == MAP_FAILED) {
MTCP_PRINTF("***Error: mmap failed; errno: %d\n", mtcp_sys_errno);
mtcp_abort();
}
mtcp_readfile(fd, addr, area.size);
if (mtcp_sys_munmap(addr, area.size) == -1) {
MTCP_PRINTF("***Error: munmap failed; errno: %d\n", mtcp_sys_errno);
mtcp_abort();
}
}
mtcp_printf("%p-%p %c%c%c%c "
// "%x %u:%u %u"
" %s\n",
area.addr, area.addr + area.size,
( area.prot & PROT_READ ? 'r' : '-' ),
( area.prot & PROT_WRITE ? 'w' : '-' ),
( area.prot & PROT_EXEC ? 'x' : '-' ),
( area.flags & MAP_SHARED ? 's'
: ( area.flags & MAP_ANONYMOUS ? 'p' : '-' ) ),
//area.offset, area.devmajor, area.devminor, area.inodenum,
area.name);
}
}
void mtcp_skipfile(int fd, size_t size)
{
VA tmp_addr = mtcp_sys_mmap(0, size, PROT_WRITE | PROT_READ,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (tmp_addr == MAP_FAILED) {
MTCP_PRINTF("mtcp_sys_mmap() failed with error: %d", mtcp_sys_errno);
mtcp_abort();
}
mtcp_readfile(fd, tmp_addr, size);
if (mtcp_sys_munmap(tmp_addr, size) == -1) {
MTCP_PRINTF("mtcp_sys_munmap() failed with error: %d", mtcp_sys_errno);
mtcp_abort();
}
}
NO_OPTIMIZE
static void restart_fast_path()
{
int mtcp_sys_errno;
void *addr = mtcp_sys_mmap(rinfo.restore_addr, rinfo.restore_size,
PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (addr == MAP_FAILED) {
MTCP_PRINTF("mmap failed with error; errno: %d\n", mtcp_sys_errno);
mtcp_abort();
}
size_t offset = (char*)&restorememoryareas - rinfo.text_addr;
rinfo.restorememoryareas_fptr = (fnptr_t)(rinfo.restore_addr + offset);
/* For __arm__
* should be able to use kernel call: __ARM_NR_cacheflush(start, end, flag)
* followed by copying new text below, followed by DSB and ISB,
* to eliminstate need for delay loop. But this needs more testing.
*/
mtcp_memcpy(rinfo.restore_addr, rinfo.text_addr, rinfo.text_size);
mtcp_memcpy(rinfo.restore_addr + rinfo.text_size, &rinfo, sizeof(rinfo));
void *stack_ptr = rinfo.restore_addr + rinfo.restore_size - MB;
#if defined(__INTEL_COMPILER) && defined(__x86_64__)
memfence();
asm volatile (CLEAN_FOR_64_BIT(mov %0,%%esp;)
void mtcp_rename_ckptfile(const char *tempckpt, const char *permckpt)
{
if (mtcp_sys_rename(tempckpt, permckpt) < 0) {
MTCP_PRINTF("error %d renaming %s to %s\n",
mtcp_sys_errno, tempckpt, permckpt);
mtcp_abort ();
}
}
void mtcp_readcs(int fd, char cs)
{
char xcs;
mtcp_readfile (fd, &xcs, sizeof xcs);
if (xcs != cs) {
MTCP_PRINTF("checkpoint section %d next, expected %d\n", xcs, cs);
mtcp_abort ();
}
}
/**
* This function will return the first character of the given file. If the
* file is not readable, we will abort.
*
* @param filename the name of the file to read
* @return the first character of the given file
*/
static char first_char(char *filename)
{
int fd, rc;
char c;
fd = mtcp_sys_open(filename, O_RDONLY, 0);
if(fd < 0)
{
MTCP_PRINTF("ERROR: Cannot open file %s\n", filename);
mtcp_abort();
}
rc = mtcp_sys_read(fd, &c, 1);
if(rc != 1)
{
MTCP_PRINTF("ERROR: Error reading from file %s\n", filename);
mtcp_abort();
}
mtcp_sys_close(fd);
return c;
}
void mtcp_readfile(int fd, void *buf, size_t size)
{
ssize_t rc;
size_t ar = 0;
int tries = 0;
while(ar != size) {
rc = mtcp_sys_read(fd, (char*)buf + ar, size - ar);
if (rc < 0 && rc > -4096) { /* kernel could return large unsigned int */
MTCP_PRINTF("error %d reading checkpoint\n", mtcp_sys_errno);
mtcp_abort();
}
else if (rc == 0) {
MTCP_PRINTF("only read %u bytes instead of %u from checkpoint file\n",
(unsigned)ar, (unsigned)size);
if (tries++ >= 10) {
MTCP_PRINTF(" failed to read after 10 tries in a row.\n");
mtcp_abort();
}
}
ar += rc;
}
}
void mtcp_writefile (int fd, void const *buff, size_t size)
{
char const *bf;
ssize_t rc;
size_t sz, wt;
static char zeroes[MTCP_PAGE_SIZE] = { 0 };
//checkpointsize += size;
bf = buff;
sz = size;
while (sz > 0) {
for (wt = sz; wt > 0; wt /= 2) {
rc = mtcp_sys_write (fd, bf, wt);
if ((rc >= 0) || (mtcp_sys_errno != EFAULT)) break;
}
/* Sometimes image page alignment will leave a hole in the middle of an
* image ... but the idiot proc/self/maps will include it anyway
*/
if (wt == 0) {
rc = (sz > sizeof zeroes ? sizeof zeroes : sz);
//checkpointsize -= rc; /* Correct now, since mtcp_writefile will add rc
// back */
mtcp_writefile (fd, zeroes, rc);
}
/* Otherwise, check for real error */
else {
if (rc == 0) mtcp_sys_errno = EPIPE;
if (rc <= 0) {
MTCP_PRINTF("Error %d writing from %p to checkpoint file.\n",
mtcp_sys_errno, bf);
mtcp_abort ();
}
}
/* It's ok, we're on to next part */
sz -= rc;
bf += rc;
}
}
void __stack_chk_fail_local(void)
{
MTCP_PRINTF("ERROR: Stack Overflow detected.\n");
mtcp_abort();
}
void __stack_chk_guard(void)
{
MTCP_PRINTF("ERROR: Stack Overflow detected.\n");
mtcp_abort();
}
void _Unwind_Resume(void)
{
MTCP_PRINTF("MTCP Internal Error: %s Not Implemented.\n", __FUNCTION__);
mtcp_abort();
}
NO_OPTIMIZE
int main(int argc, char *argv[], char **environ)
{
char *ckptImage = NULL;
MtcpHeader mtcpHdr;
int mtcp_sys_errno;
int simulate = 0;
if (argc == 1) {
MTCP_PRINTF("***ERROR: This program should not be used directly.\n");
mtcp_sys_exit(1);
}
#if 0
MTCP_PRINTF("Attach for debugging.");
{int x=1; while(x);}
#endif
// TODO(karya0): Remove vDSO checks after 2.4.0-rc3 release, and after testing.
// Without mtcp_check_vdso, CentOS 7 fails on dmtcp3, dmtcp5, others.
#define ENABLE_VDSO_CHECK
// TODO(karya0): Remove this block and the corresponding file after sufficient
// testing: including testing for __i386__, __arm__ and __aarch64__
#ifdef ENABLE_VDSO_CHECK
/* i386 uses random addresses for vdso. Make sure that its location
* will not conflict with other memory regions.
* (Other arch's may also need this in the future. So, we do it for all.)
* Note that we may need to keep the old and the new vdso. We may
* have checkpointed inside gettimeofday inside the old vdso, and the
* kernel, on restart, knows only the new vdso.
*/
mtcp_check_vdso(environ);
#endif
rinfo.fd = -1;
rinfo.use_gdb = 0;
rinfo.text_offset = -1;
shift;
while (argc > 0) {
// Flags for standalone debugging
if (argc == 1) {
// We would use MTCP_PRINTF, but it's also for output of util/readdmtcp.sh
mtcp_printf("Considering '%s' as a ckpt image.\n", argv[0]);
ckptImage = argv[0];
break;
} else if (mtcp_strcmp(argv[0], "--use-gdb") == 0) {
rinfo.use_gdb = 1;
shift;
} else if (mtcp_strcmp(argv[0], "--text-offset") == 0) {
rinfo.text_offset = mtcp_strtol(argv[1]);
shift; shift;
// Flags for call by dmtcp_restart follow here:
} else if (mtcp_strcmp(argv[0], "--fd") == 0) {
rinfo.fd = mtcp_strtol(argv[1]);
shift; shift;
} else if (mtcp_strcmp(argv[0], "--stderr-fd") == 0) {
rinfo.stderr_fd = mtcp_strtol(argv[1]);
shift; shift;
} else if (mtcp_strcmp(argv[0], "--simulate") == 0) {
simulate = 1;
shift;
} else {
MTCP_PRINTF("MTCP Internal Error\n");
return -1;
}
}
if ((rinfo.fd != -1) ^ (ckptImage == NULL)) {
MTCP_PRINTF("***MTCP Internal Error\n");
mtcp_abort();
}
if (rinfo.fd != -1) {
mtcp_readfile(rinfo.fd, &mtcpHdr, sizeof mtcpHdr);
} else {
int rc = -1;
rinfo.fd = mtcp_sys_open2(ckptImage, O_RDONLY);
if (rinfo.fd == -1) {
MTCP_PRINTF("***ERROR opening ckpt image (%s); errno: %d\n",
ckptImage, mtcp_sys_errno);
mtcp_abort();
}
// This assumes that the MTCP header signature is unique.
// We repeatedly look for mtcpHdr because the first header will be
// for DMTCP. So, we look deeper for the MTCP header. The MTCP
// header is guaranteed to start on an offset that's an integer
// multiple of sizeof(mtcpHdr), which is currently 4096 bytes.
do {
rc = mtcp_readfile(rinfo.fd, &mtcpHdr, sizeof mtcpHdr);
} while (rc > 0 && mtcp_strcmp(mtcpHdr.signature, MTCP_SIGNATURE) != 0);
if (rc == 0) { /* if end of file */
MTCP_PRINTF("***ERROR: ckpt image doesn't match MTCP_SIGNATURE\n");
return 1; /* exit with error code 1 */
}
}
DPRINTF("For debugging:\n"
" (gdb) add-symbol-file ../../bin/mtcp_restart %p\n",
mtcpHdr.restore_addr + rinfo.text_offset);
if (rinfo.text_offset == -1)
DPRINTF("... but add to the above the result, 1 +"
" `text_offset.sh mtcp_restart`\n in the mtcp subdirectory.\n");
if (simulate) {
mtcp_simulateread(rinfo.fd, &mtcpHdr);
return 0;
}
rinfo.saved_brk = mtcpHdr.saved_brk;
rinfo.restore_addr = mtcpHdr.restore_addr;
rinfo.restore_end = mtcpHdr.restore_addr + mtcpHdr.restore_size;
rinfo.restore_size = mtcpHdr.restore_size;
rinfo.vdsoStart = mtcpHdr.vdsoStart;
rinfo.vdsoEnd = mtcpHdr.vdsoEnd;
rinfo.vvarStart = mtcpHdr.vvarStart;
rinfo.vvarEnd = mtcpHdr.vvarEnd;
rinfo.post_restart = mtcpHdr.post_restart;
rinfo.motherofall_tls_info = mtcpHdr.motherofall_tls_info;
rinfo.tls_pid_offset = mtcpHdr.tls_pid_offset;
rinfo.tls_tid_offset = mtcpHdr.tls_tid_offset;
rinfo.myinfo_gs = mtcpHdr.myinfo_gs;
restore_brk(rinfo.saved_brk, rinfo.restore_addr,
rinfo.restore_addr + rinfo.restore_size);
getTextAddr(&rinfo.text_addr, &rinfo.text_size);
if (hasOverlappingMapping(rinfo.restore_addr, rinfo.restore_size)) {
MTCP_PRINTF("*** Not Implemented.\n\n");
mtcp_abort();
restart_slow_path();
} else {
restart_fast_path();
}
return 0; /* Will not reach here, but need to satisfy the compiler */
}
/**
* This function will open the checkpoint file stored at the given filename.
* It will check the magic number and take the appropriate action. If the
* magic number is unknown, we will abort. The fd returned points to the
* beginning of the uncompressed data.
* NOTE: related code in ../dmtcp/src/connectionmanager.cpp:open_ckpt_to_read()
*
* @param filename the name of the checkpoint file
* @return the fd to use
*/
static int open_ckpt_to_read(char *filename, char *envp[])
{
int fd;
int fds[2];
char fc;
char *gzip_cmd = "gzip";
static char *gzip_args[] = { "gzip", "-d", "-", NULL };
#ifdef HBICT_DELTACOMP
char *hbict_cmd = "hbict";
static char *hbict_args[] = { "hbict", "-r", NULL };
#endif
char decomp_path[PATH_MAX];
static char **decomp_args;
pid_t cpid;
fc = first_char(filename);
fd = mtcp_sys_open(filename, O_RDONLY, 0);
if(fd < 0) {
MTCP_PRINTF("ERROR: Cannot open checkpoint file %s\n", filename);
mtcp_abort();
}
if (fc == MAGIC_FIRST || fc == 'D') /* no compression ('D' from DMTCP) */
return fd;
else if (fc == GZIP_FIRST
#ifdef HBICT_DELTACOMP
|| fc == HBICT_FIRST
#endif
) { /* Set prog_path */
if( fc == GZIP_FIRST ){
decomp_args = gzip_args;
if( mtcp_find_executable(gzip_cmd, getenv("PATH"),
decomp_path) == NULL ) {
MTCP_PRINTF("ERROR: Cannot find gunzip to decompress ckpt file!\n");
mtcp_abort();
}
}
#ifdef HBICT_DELTACOMP
if( fc == HBICT_FIRST ){
decomp_args = hbict_args;
if( mtcp_find_executable(hbict_cmd, getenv("PATH"),
decomp_path) == NULL ) {
MTCP_PRINTF("ERROR: Cannot find hbict to decompress ckpt file!\n");
mtcp_abort();
}
}
#endif
if (mtcp_sys_pipe(fds) == -1) {
MTCP_PRINTF("ERROR: Cannot create pipe to execute gunzip to decompress"
" checkpoint file!\n");
mtcp_abort();
}
cpid = mtcp_sys_fork();
if(cpid == -1) {
MTCP_PRINTF("ERROR: Cannot fork to execute gunzip to decompress"
" checkpoint file!\n");
mtcp_abort();
}
else if(cpid > 0) /* parent process */ {
decomp_child_pid = cpid;
mtcp_sys_close(fd);
mtcp_sys_close(fds[1]);
return fds[0];
}
else /* child process */ {
fd = mtcp_sys_dup(mtcp_sys_dup(mtcp_sys_dup(fd)));
if (fd == -1) {
MTCP_PRINTF("ERROR: dup() failed! No restoration will be performed!"
" Cancel now!\n");
mtcp_abort();
}
fds[1] = mtcp_sys_dup(fds[1]);
mtcp_sys_close(fds[0]);
if (mtcp_sys_dup2(fd, STDIN_FILENO) != STDIN_FILENO) {
MTCP_PRINTF("ERROR: dup2() failed! No restoration will be performed!"
" Cancel now!\n");
mtcp_abort();
}
mtcp_sys_close(fd);
mtcp_sys_dup2(fds[1], STDOUT_FILENO);
mtcp_sys_close(fds[1]);
mtcp_sys_execve(decomp_path, decomp_args, envp);
/* should not get here */
MTCP_PRINTF("ERROR: Decompression failed! No restoration will be"
" performed! Cancel now!\n");
mtcp_abort();
}
}
else /* invalid magic number */ {
MTCP_PRINTF("ERROR: Invalid magic number in this checkpoint file!\n");
mtcp_abort();
}
}
void __gcc_personality_v0(void)
{
MTCP_PRINTF("MTCP Internal Error: %s Not Implemented.\n", __FUNCTION__);
mtcp_abort();
}
int main (int argc, char *argv[], char *envp[])
{
char magicbuf[MAGIC_LEN], *restorename;
int fd, verify;
size_t restore_size, offset=0;
void *restore_begin, *restore_mmap;
void (*restore_start) (int fd, int verify, pid_t decomp_child_pid,
char *ckpt_newname, char *cmd_file,
char *argv[], char *envp[]);
char cmd_file[PATH_MAX+1];
char ckpt_newname[PATH_MAX+1] = "";
char **orig_argv = argv;
int orig_argc = argc;
environ = envp;
if (mtcp_sys_getuid() == 0 || mtcp_sys_geteuid() == 0) {
mtcp_printf("Running mtcp_restart as root is dangerous. Aborting.\n" \
"If you still want to do this (at your own risk)," \
" then modify mtcp/%s:%d and re-compile.\n",
__FILE__, __LINE__ - 4);
mtcp_abort();
}
// Turn off randomize_va (by re-exec'ing) or warn user if vdso_enabled is on.
mtcp_check_vdso_enabled();
fd = decomp_child_pid = -1;
verify = 0;
shift;
while (1) {
if (argc == 0 || (mtcp_strcmp(argv[0], "--help") == 0 && argc == 1)) {
mtcp_printf("%s", theUsage);
return (-1);
} else if (mtcp_strcmp (argv[0], "--version") == 0 && argc == 1) {
mtcp_printf("%s", VERSION_AND_COPYRIGHT_INFO);
return (-1);
} else if (mtcp_strcmp (argv[0], "--verify") == 0 && argc == 2) {
verify = 1;
restorename = argv[1];
break;
} else if (mtcp_strcmp (argv[0], "--offset") == 0 && argc >= 3) {
offset = mtcp_atoi(argv[1]);
shift; shift;
} else if (mtcp_strcmp (argv[0], "--fd") == 0 && argc >= 2) {
fd = mtcp_atoi(argv[1]);
shift; shift;
} else if (mtcp_strcmp (argv[0], "--gzip-child-pid") == 0 && argc >= 2) {
decomp_child_pid = mtcp_atoi(argv[1]);
shift; shift;
} else if (mtcp_strcmp (argv[0], "--rename-ckpt") == 0 && argc >= 2) {
mtcp_strncpy(ckpt_newname, argv[1], PATH_MAX);
shift; shift;
} else if (mtcp_strcmp (argv[0], "--stderr-fd") == 0 && argc >= 2) {
// If using with DMTCP/jassert, Pass in a non-standard stderr
dmtcp_info_stderr_fd = mtcp_atoi(argv[1]);
shift; shift;
} else if (mtcp_strcmp (argv[0], "--") == 0 && argc == 2) {
restorename = argv[1];
break;
} else if (argc == 1) {
restorename = argv[0];
break;
} else {
mtcp_printf("%s", theUsage);
return (-1);
}
}
// Restore argc and argv pointer
argv = orig_argv;
argc = orig_argc;
/* XXX XXX XXX:
* DO NOT USE mtcp_printf OR DPRINTF BEFORE THIS BLOCK, IT'S DANGEROUS AND
* CAN MESS UP YOUR PROCESSES BY WRITING GARBAGE TO THEIR STDERR FD,
* IF THEY ARE NOT USING IT AS STDERR.
* --Kapil
*/
if (fd != -1 && decomp_child_pid != -1) {
restorename = NULL;
} else if ((fd == -1 && decomp_child_pid != -1) ||
(offset != 0 && fd != -1)) {
mtcp_printf("%s", theUsage);
return (-1);
}
if (restorename) {
#if 1
if (mtcp_sys_access(restorename, R_OK) != 0 && mtcp_sys_errno == EACCES) {
MTCP_PRINTF("\nProcess does not have read permission for\n" \
" checkpoint image (%s).\n" \
" (Check file permissions, UIDs etc.)\n",
restorename);
mtcp_abort();
}
#else
struct stat buf;
int rc = mtcp_sys_stat(restorename, &buf);
if (rc == -1) {
MTCP_PRINTF("Error %d stat()'ing ckpt image %s.",
mtcp_sys_errno, restorename);
mtcp_abort();
} else if (buf.st_uid != mtcp_sys_getuid()) { /*Could also run if geteuid()
matches*/
MTCP_PRINTF("\nProcess uid (%d) doesn't match uid (%d) of\n" \
" checkpoint image (%s).\n" \
"This is dangerous. Aborting for security reasons.\n" \
"If you still want to do this, modify mtcp/%s:%d and"
" re-compile.\n",
mtcp_sys_getuid(), buf.st_uid, restorename,
__FILE__, __LINE__ - 5);
mtcp_abort();
}
#endif
}
if (mtcp_strlen(ckpt_newname) == 0 && restorename != NULL && offset != 0) {
mtcp_strncpy(ckpt_newname, restorename, PATH_MAX);
}
if (restorename!=NULL) fd = open_ckpt_to_read(restorename, envp);
if (offset>0) {
//skip into the file a bit
VA addr = (VA) mtcp_sys_mmap(0, offset, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (addr == MAP_FAILED) {
MTCP_PRINTF("mmap failed with error %d\n", mtcp_sys_errno);
mtcp_abort();
}
mtcp_readfile(fd, addr, offset);
if (mtcp_sys_munmap(addr, offset) == -1) {
MTCP_PRINTF("munmap failed with error %d\n", mtcp_sys_errno);
mtcp_abort();
}
}
mtcp_memset(magicbuf, 0, sizeof magicbuf);
mtcp_readfile (fd, magicbuf, MAGIC_LEN);
if (mtcp_memcmp (magicbuf, MAGIC, MAGIC_LEN) != 0) {
MTCP_PRINTF("'%s' is '%s', but this restore is '%s' (fd=%d)\n",
restorename, magicbuf, MAGIC, fd);
return (-1);
}
/* Set the resource limits for stack from saved values */
struct rlimit stack_rlimit;
#ifdef FAST_CKPT_RST_VIA_MMAP
Area area;
fastckpt_read_header(fd, &stack_rlimit, &area, (VA*) &restore_start);
restore_begin = area.addr;
restore_size = area.size;
#else
mtcp_readcs (fd, CS_STACKRLIMIT); /* resource limit for stack */
mtcp_readfile (fd, &stack_rlimit, sizeof stack_rlimit);
/* Find where the restore image goes */
mtcp_readcs (fd, CS_RESTOREBEGIN); /* beginning of checkpointed libmtcp.so image */
mtcp_readfile (fd, &restore_begin, sizeof restore_begin);
mtcp_readcs (fd, CS_RESTORESIZE); /* size of checkpointed libmtcp.so image */
mtcp_readfile (fd, &restore_size, sizeof restore_size);
mtcp_readcs (fd, CS_RESTORESTART);
mtcp_readfile (fd, &restore_start, sizeof restore_start);
DPRINTF("saved stack resource limit: soft_lim:%p, hard_lim:%p\n",
stack_rlimit.rlim_cur, stack_rlimit.rlim_max);
#endif // FAST_CKPT_RST_VIA_MMAP
mtcp_sys_setrlimit(RLIMIT_STACK, &stack_rlimit);
/* Read in the restore image to same address where it was loaded at time
* of checkpoint. This is libmtcp.so, including both text and data sections
* as a single section. Hence, we need both write and exec permission,
* and MAP_ANONYMOUS, since the data could have changed.
*/
DPRINTF("restoring anonymous area %p at %p\n", restore_size, restore_begin);
if (mtcp_sys_munmap(restore_begin, restore_size) < 0) {
MTCP_PRINTF("failed to unmap region at %p\n", restore_begin);
mtcp_abort ();
}
#ifdef FAST_CKPT_RST_VIA_MMAP
fastckpt_load_restore_image(fd, &area);
#else
restore_mmap = mtcp_safemmap (restore_begin, restore_size,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_ANONYMOUS | MAP_FIXED | MAP_PRIVATE, -1, 0);
if (restore_mmap == MAP_FAILED) {
#ifndef _XOPEN_UNIX
MTCP_PRINTF("Does mmap here support MAP_FIXED?\n");
#endif
if (mtcp_sys_errno != EBUSY) {
MTCP_PRINTF("Error %d creating %p byte restore region at %p.\n",
mtcp_sys_errno, restore_size, restore_begin);
mtcp_abort ();
} else {
MTCP_PRINTF("restarting due to address conflict...\n");
mtcp_sys_close (fd);
mtcp_sys_execve (argv[0], argv, envp);
}
}
if (restore_mmap != restore_begin) {
MTCP_PRINTF("%p byte restore region at %p got mapped at %p\n",
restore_size, restore_begin, restore_mmap);
mtcp_abort ();
}
mtcp_readcs (fd, CS_RESTOREIMAGE);
mtcp_readfile (fd, restore_begin, restore_size);
#endif
#ifndef __x86_64__
// Copy command line to libmtcp.so, so that we can re-exec if randomized vdso
// steps on us. This won't be needed when we use the linker to map areas.
cmd_file[0] = '\0';
{ int cmd_len = mtcp_sys_readlink("/proc/self/exe", cmd_file, PATH_MAX);
if (cmd_len == -1)
MTCP_PRINTF("WARNING: Couldn't find /proc/self/exe."
" Trying to continue anyway.\n");
else
cmd_file[cmd_len] = '\0';
}
#endif
#ifdef LIBC_STATIC_AVAILABLE
/********************************************************************
* Apparently, there is no consistent way to define LIBC_STATIC_AVAILABLE.
* The purpose of the code below is to be able to use a symbolic debugger
* like gdb when dmtcp_restart calls MTCP. It would print a command that
* you can paste into gdb to allow debugging inside the function restore_start.
* When "ifdef LIBC_STATIC_AVAILABLE" was added, mtcp/Makefile was modified
* to forbid using functions from libc.a like popen. If you want to debug
* restore_start(), you should read the code below and manually calculate
* by hand what this used to automatically calculate. For a semi-automated
* substitute, when you reach restore_start(), call it with (gdb) si
* Then try: (gdb) shell ../utils/gdb-add-libmtcp-symbol-file.py
* where ADDR will be restore_start or an arb. address in restore_start()
********************************************************************/
# ifdef DEBUG
char *p, symbolbuff[256];
FILE *symbolfile;
long textbase; /* offset */
MTCP_PRINTF("restore_begin=%p, restore_start=%p\n",
restore_begin, restore_start);
textbase = 0;
symbolfile = popen ("readelf -S libmtcp.so", "r");
if (symbolfile != NULL) {
while (fgets (symbolbuff, sizeof symbolbuff, symbolfile) != NULL) {
if (memcmp (symbolbuff + 5, "] .text ", 8) == 0) {
textbase = strtoul (symbolbuff + 41, &p, 16);
}
}
pclose (symbolfile);
if (textbase != 0) {
mtcp_printf("\n**********\nmtcp_restart*: The symbol table of the"
" checkpointed file can be\nmade available to gdb."
" Just type the command below in gdb:\n");
mtcp_printf(" add-symbol-file libmtcp.so %p\n",
restore_begin + textbase);
mtcp_printf("Then type \"continue\" to continue debugging.\n");
mtcp_printf("**********\n");
}
}
mtcp_maybebpt ();
# endif
#endif
/* Now call it - it shouldn't return */
(*restore_start) (fd, verify, decomp_child_pid, ckpt_newname, cmd_file, argv, envp);
MTCP_PRINTF("restore routine returned (it should never do this!)\n");
mtcp_abort ();
return (0);
}