/* Low level interface to ptrace, for the remote server for GDB.
Copyright (C) 1995, 1996, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
- 2006
- Free Software Foundation, Inc.
+ 2006, 2007 Free Software Foundation, Inc.
This file is part of GDB.
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
+ the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
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., 51 Franklin Street, Fifth Floor,
- Boston, MA 02110-1301, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "server.h"
#include "linux-low.h"
#include <unistd.h>
#include <errno.h>
#include <sys/syscall.h>
+#include <sched.h>
#ifndef PTRACE_GETSIGINFO
# define PTRACE_GETSIGINFO 0x4202
# define PTRACE_SETSIGINFO 0x4203
#endif
-/* ``all_threads'' is keyed by the LWP ID - it should be the thread ID instead,
- however. This requires changing the ID in place when we go from !using_threads
- to using_threads, immediately.
+#ifndef O_LARGEFILE
+#define O_LARGEFILE 0
+#endif
+
+/* If the system headers did not provide the constants, hard-code the normal
+ values. */
+#ifndef PTRACE_EVENT_FORK
+
+#define PTRACE_SETOPTIONS 0x4200
+#define PTRACE_GETEVENTMSG 0x4201
+
+/* options set using PTRACE_SETOPTIONS */
+#define PTRACE_O_TRACESYSGOOD 0x00000001
+#define PTRACE_O_TRACEFORK 0x00000002
+#define PTRACE_O_TRACEVFORK 0x00000004
+#define PTRACE_O_TRACECLONE 0x00000008
+#define PTRACE_O_TRACEEXEC 0x00000010
+#define PTRACE_O_TRACEVFORKDONE 0x00000020
+#define PTRACE_O_TRACEEXIT 0x00000040
+
+/* Wait extended result codes for the above trace options. */
+#define PTRACE_EVENT_FORK 1
+#define PTRACE_EVENT_VFORK 2
+#define PTRACE_EVENT_CLONE 3
+#define PTRACE_EVENT_EXEC 4
+#define PTRACE_EVENT_VFORK_DONE 5
+#define PTRACE_EVENT_EXIT 6
+
+#endif /* PTRACE_EVENT_FORK */
+
+/* We can't always assume that this flag is available, but all systems
+ with the ptrace event handlers also have __WALL, so it's safe to use
+ in some contexts. */
+#ifndef __WALL
+#define __WALL 0x40000000 /* Wait for any child. */
+#endif
+
+#ifdef __UCLIBC__
+#if !(defined(__UCLIBC_HAS_MMU__) || defined(__ARCH_HAS_MMU__))
+#define HAS_NOMMU
+#endif
+#endif
+
+/* ``all_threads'' is keyed by the LWP ID, which we use as the GDB protocol
+ representation of the thread ID.
``all_processes'' is keyed by the process ID - which on Linux is (presently)
the same as the LWP ID. */
struct inferior_list all_processes;
+/* A list of all unknown processes which receive stop signals. Some other
+ process will presumably claim each of these as forked children
+ momentarily. */
+
+struct inferior_list stopped_pids;
+
/* FIXME this is a bit of a hack, and could be removed. */
int stopping_threads;
/* FIXME make into a target method? */
-int using_threads;
+int using_threads = 1;
+static int thread_db_active;
+
+static int must_set_ptrace_flags;
static void linux_resume_one_process (struct inferior_list_entry *entry,
int step, int signal, siginfo_t *info);
static void linux_resume (struct thread_resume *resume_info);
static void stop_all_processes (void);
static int linux_wait_for_event (struct thread_info *child);
+static int check_removed_breakpoint (struct process_info *event_child);
+static void *add_process (unsigned long pid);
struct pending_signals
{
static int use_regsets_p = 1;
#endif
-int debug_threads = 0;
-
#define pid_of(proc) ((proc)->head.id)
/* FIXME: Delete eventually. */
#define inferior_pid (pid_of (get_thread_process (current_inferior)))
+static void
+handle_extended_wait (struct process_info *event_child, int wstat)
+{
+ int event = wstat >> 16;
+ struct process_info *new_process;
+
+ if (event == PTRACE_EVENT_CLONE)
+ {
+ unsigned long new_pid;
+ int ret, status;
+
+ ptrace (PTRACE_GETEVENTMSG, inferior_pid, 0, &new_pid);
+
+ /* If we haven't already seen the new PID stop, wait for it now. */
+ if (! pull_pid_from_list (&stopped_pids, new_pid))
+ {
+ /* The new child has a pending SIGSTOP. We can't affect it until it
+ hits the SIGSTOP, but we're already attached. */
+
+ do {
+ ret = waitpid (new_pid, &status, __WALL);
+ } while (ret == -1 && errno == EINTR);
+
+ if (ret == -1)
+ perror_with_name ("waiting for new child");
+ else if (ret != new_pid)
+ warning ("wait returned unexpected PID %d", ret);
+ else if (!WIFSTOPPED (status))
+ warning ("wait returned unexpected status 0x%x", status);
+ }
+
+ ptrace (PTRACE_SETOPTIONS, new_pid, 0, PTRACE_O_TRACECLONE);
+
+ new_process = (struct process_info *) add_process (new_pid);
+ add_thread (new_pid, new_process, new_pid);
+ new_thread_notify (thread_id_to_gdb_id (new_process->lwpid));
+
+ /* Normally we will get the pending SIGSTOP. But in some cases
+ we might get another signal delivered to the group first.
+ If we do, be sure not to lose it. */
+ if (WSTOPSIG (status) == SIGSTOP)
+ {
+ if (stopping_threads)
+ new_process->stopped = 1;
+ else
+ ptrace (PTRACE_CONT, new_pid, 0, 0);
+ }
+ else
+ {
+ new_process->stop_expected = 1;
+ if (stopping_threads)
+ {
+ new_process->stopped = 1;
+ new_process->status_pending_p = 1;
+ new_process->status_pending = status;
+ }
+ else
+ /* Pass the signal on. This is what GDB does - except
+ shouldn't we really report it instead? */
+ ptrace (PTRACE_CONT, new_pid, 0, WSTOPSIG (status));
+ }
+
+ /* Always resume the current thread. If we are stopping
+ threads, it will have a pending SIGSTOP; we may as well
+ collect it now. */
+ linux_resume_one_process (&event_child->head,
+ event_child->stepping, 0, NULL);
+ }
+}
+
/* This function should only be called if the process got a SIGTRAP.
The SIGTRAP could mean several things.
memset (process, 0, sizeof (*process));
process->head.id = pid;
-
- /* Default to tid == lwpid == pid. */
- process->tid = pid;
process->lwpid = pid;
add_inferior_to_list (&all_processes, &process->head);
void *new_process;
int pid;
-#if defined(__UCLIBC__) && !defined(__UCLIBC_HAS_MMU__)
+#if defined(__UCLIBC__) && defined(HAS_NOMMU)
pid = vfork ();
#else
pid = fork ();
setpgid (0, 0);
execv (program, allargs);
+ if (errno == ENOENT)
+ execvp (program, allargs);
fprintf (stderr, "Cannot exec %s: %s.\n", program,
strerror (errno));
new_process = add_process (pid);
add_thread (pid, new_process, pid);
+ must_set_ptrace_flags = 1;
return pid;
}
/* Attach to an inferior process. */
void
-linux_attach_lwp (unsigned long pid, unsigned long tid)
+linux_attach_lwp (unsigned long pid)
{
struct process_info *new_process;
fflush (stderr);
/* If we fail to attach to an LWP, just return. */
- if (!using_threads)
+ if (all_threads.head == NULL)
_exit (0177);
return;
}
+ ptrace (PTRACE_SETOPTIONS, pid, 0, PTRACE_O_TRACECLONE);
+
new_process = (struct process_info *) add_process (pid);
- add_thread (tid, new_process, pid);
+ add_thread (pid, new_process, pid);
+ new_thread_notify (thread_id_to_gdb_id (new_process->lwpid));
/* The next time we wait for this LWP we'll see a SIGSTOP as PTRACE_ATTACH
brings it to a halt. We should ignore that SIGSTOP and resume the process
{
struct process_info *process;
- linux_attach_lwp (pid, pid);
+ linux_attach_lwp (pid);
- /* Don't ignore the initial SIGSTOP if we just attached to this process. */
+ /* Don't ignore the initial SIGSTOP if we just attached to this process.
+ It will be collected by wait shortly. */
process = (struct process_info *) find_inferior_id (&all_processes, pid);
process->stop_expected = 0;
struct thread_info *thread = (struct thread_info *) entry;
struct process_info *process = get_thread_process (thread);
+ /* Make sure the process isn't stopped at a breakpoint that's
+ no longer there. */
+ check_removed_breakpoint (process);
+
+ /* If this process is stopped but is expecting a SIGSTOP, then make
+ sure we take care of that now. This isn't absolutely guaranteed
+ to collect the SIGSTOP, but is fairly likely to. */
+ if (process->stop_expected)
+ {
+ /* Clear stop_expected, so that the SIGSTOP will be reported. */
+ process->stop_expected = 0;
+ if (process->stopped)
+ linux_resume_one_process (&process->head, 0, 0, NULL);
+ linux_wait_for_event (thread);
+ }
+
+ /* Flush any pending changes to the process's registers. */
+ regcache_invalidate_one ((struct inferior_list_entry *)
+ get_process_thread (process));
+
+ /* Finally, let it resume. */
ptrace (PTRACE_DETACH, pid_of (process), 0, 0);
}
-static void
+static int
linux_detach (void)
{
+ delete_all_breakpoints ();
for_each_inferior (&all_threads, linux_detach_one_process);
+ clear_inferiors ();
+ return 0;
+}
+
+static void
+linux_join (void)
+{
+ extern unsigned long signal_pid;
+ int status, ret;
+
+ do {
+ ret = waitpid (signal_pid, &status, 0);
+ if (WIFEXITED (status) || WIFSIGNALED (status))
+ break;
+ } while (ret != -1 || errno != ECHILD);
}
/* Return nonzero if the given thread is still alive. */
static int
-linux_thread_alive (unsigned long tid)
+linux_thread_alive (unsigned long lwpid)
{
- if (find_inferior_id (&all_threads, tid) != NULL)
+ if (find_inferior_id (&all_threads, lwpid) != NULL)
return 1;
else
return 0;
return 0;
if (debug_threads)
- fprintf (stderr, "Checking for breakpoint.\n");
+ fprintf (stderr, "Checking for breakpoint in process %ld.\n",
+ event_child->lwpid);
saved_inferior = current_inferior;
current_inferior = get_process_thread (event_child);
if (stop_pc != event_child->pending_stop_pc)
{
if (debug_threads)
- fprintf (stderr, "Ignoring, PC was changed.\n");
+ fprintf (stderr, "Ignoring, PC was changed. Old PC was 0x%08llx\n",
+ event_child->pending_stop_pc);
event_child->pending_is_breakpoint = 0;
current_inferior = saved_inferior;
if (*childp != NULL)
to_wait_for = (*childp)->lwpid;
+retry:
while (1)
{
ret = waitpid (to_wait_for, wstatp, WNOHANG);
if (to_wait_for == -1)
*childp = (struct process_info *) find_inferior_id (&all_processes, ret);
+ /* If we didn't find a process, one of two things presumably happened:
+ - A process we started and then detached from has exited. Ignore it.
+ - A process we are controlling has forked and the new child's stop
+ was reported to us by the kernel. Save its PID. */
+ if (*childp == NULL && WIFSTOPPED (*wstatp))
+ {
+ add_pid_to_list (&stopped_pids, ret);
+ goto retry;
+ }
+ else if (*childp == NULL)
+ goto retry;
+
(*childp)->stopped = 1;
(*childp)->pending_is_breakpoint = 0;
&& WIFSTOPPED (*wstatp))
{
current_inferior = (struct thread_info *)
- find_inferior_id (&all_threads, (*childp)->tid);
+ find_inferior_id (&all_threads, (*childp)->lwpid);
/* For testing only; i386_stop_pc prints out a diagnostic. */
if (the_low_target.get_pc != NULL)
get_stop_pc ();
error ("event from unknown child");
current_inferior = (struct thread_info *)
- find_inferior_id (&all_threads, event_child->tid);
+ find_inferior_id (&all_threads, event_child->lwpid);
/* Check for thread exit. */
- if (using_threads && ! WIFSTOPPED (wstat))
+ if (! WIFSTOPPED (wstat))
{
if (debug_threads)
- fprintf (stderr, "Thread %ld (LWP %ld) exiting\n",
- event_child->tid, event_child->head.id);
+ fprintf (stderr, "LWP %ld exiting\n", event_child->head.id);
/* If the last thread is exiting, just return. */
if (all_threads.head == all_threads.tail)
return wstat;
- dead_thread_notify (event_child->tid);
+ dead_thread_notify (thread_id_to_gdb_id (event_child->lwpid));
remove_inferior (&all_processes, &event_child->head);
free (event_child);
continue;
}
- if (using_threads
- && WIFSTOPPED (wstat)
+ if (WIFSTOPPED (wstat)
&& WSTOPSIG (wstat) == SIGSTOP
&& event_child->stop_expected)
{
continue;
}
+ if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGTRAP
+ && wstat >> 16 != 0)
+ {
+ handle_extended_wait (event_child, wstat);
+ continue;
+ }
+
/* If GDB is not interested in this signal, don't stop other
threads, and don't report it to GDB. Just resume the
inferior right away. We do this for threading-related
- signals as well as any that GDB specifically requested
- we ignore. But never ignore SIGSTOP if we sent it
- ourselves. */
+ signals as well as any that GDB specifically requested we
+ ignore. But never ignore SIGSTOP if we sent it ourselves,
+ and do not ignore signals when stepping - they may require
+ special handling to skip the signal handler. */
/* FIXME drow/2002-06-09: Get signal numbers from the inferior's
thread library? */
if (WIFSTOPPED (wstat)
- && ((using_threads && (WSTOPSIG (wstat) == __SIGRTMIN
- || WSTOPSIG (wstat) == __SIGRTMIN + 1))
- || (pass_signals[target_signal_from_host (WSTOPSIG (wstat))]
- && (WSTOPSIG (wstat) != SIGSTOP
- || !event_child->sigstop_sent))))
+ && !event_child->stepping
+ && (
+#ifdef USE_THREAD_DB
+ (thread_db_active && (WSTOPSIG (wstat) == __SIGRTMIN
+ || WSTOPSIG (wstat) == __SIGRTMIN + 1))
+ ||
+#endif
+ (pass_signals[target_signal_from_host (WSTOPSIG (wstat))]
+ && (WSTOPSIG (wstat) != SIGSTOP || !stopping_threads))))
{
siginfo_t info, *info_p;
if (debug_threads)
- fprintf (stderr, "Ignored signal %d for %ld (LWP %ld).\n",
- WSTOPSIG (wstat), event_child->tid,
- event_child->head.id);
+ fprintf (stderr, "Ignored signal %d for LWP %ld.\n",
+ WSTOPSIG (wstat), event_child->head.id);
if (ptrace (PTRACE_GETSIGINFO, event_child->lwpid, 0, &info) == 0)
info_p = &info;
stop_all_processes ();
disable_async_io ();
+ if (must_set_ptrace_flags)
+ {
+ ptrace (PTRACE_SETOPTIONS, inferior_pid, 0, PTRACE_O_TRACECLONE);
+ must_set_ptrace_flags = 0;
+ }
+
/* If we are waiting for a particular child, and it exited,
linux_wait_for_event will return its exit status. Similarly if
the last child exited. If this is not the last child, however,
send another. */
if (process->stop_expected)
{
+ if (debug_threads)
+ fprintf (stderr, "Have pending sigstop for process %ld\n",
+ process->lwpid);
+
+ /* We clear the stop_expected flag so that wait_for_sigstop
+ will receive the SIGSTOP event (instead of silently resuming and
+ waiting again). It'll be reset below. */
process->stop_expected = 0;
return;
}
fprintf (stderr, "Sending sigstop to process %ld\n", process->head.id);
kill_lwp (process->head.id, SIGSTOP);
- process->sigstop_sent = 1;
}
static void
saved_inferior = current_inferior;
saved_tid = ((struct inferior_list_entry *) saved_inferior)->id;
thread = (struct thread_info *) find_inferior_id (&all_threads,
- process->tid);
+ process->lwpid);
wstat = linux_wait_for_event (thread);
/* If we stopped with a non-SIGSTOP signal, save it for later
&& WSTOPSIG (wstat) != SIGSTOP)
{
if (debug_threads)
- fprintf (stderr, "Stopped with non-sigstop signal\n");
+ fprintf (stderr, "LWP %ld stopped with non-sigstop status %06x\n",
+ process->lwpid, wstat);
process->status_pending_p = 1;
process->status_pending = wstat;
process->stop_expected = 1;
/* Allocate buffer of that many longwords. */
register PTRACE_XFER_TYPE *buffer
= (PTRACE_XFER_TYPE *) alloca (count * sizeof (PTRACE_XFER_TYPE));
+ int fd;
+ char filename[64];
+
+ /* Try using /proc. Don't bother for one word. */
+ if (len >= 3 * sizeof (long))
+ {
+ /* We could keep this file open and cache it - possibly one per
+ thread. That requires some juggling, but is even faster. */
+ sprintf (filename, "/proc/%ld/mem", inferior_pid);
+ fd = open (filename, O_RDONLY | O_LARGEFILE);
+ if (fd == -1)
+ goto no_proc;
+
+ /* If pread64 is available, use it. It's faster if the kernel
+ supports it (only one syscall), and it's 64-bit safe even on
+ 32-bit platforms (for instance, SPARC debugging a SPARC64
+ application). */
+#ifdef HAVE_PREAD64
+ if (pread64 (fd, myaddr, len, memaddr) != len)
+#else
+ if (lseek (fd, memaddr, SEEK_SET) == -1 || read (fd, memaddr, len) != len)
+#endif
+ {
+ close (fd);
+ goto no_proc;
+ }
+
+ close (fd);
+ return 0;
+ }
+ no_proc:
/* Read all the longwords */
for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
{
return 0;
}
+static int linux_supports_tracefork_flag;
+
+/* Helper functions for linux_test_for_tracefork, called via clone (). */
+
+static int
+linux_tracefork_grandchild (void *arg)
+{
+ _exit (0);
+}
+
+static int
+linux_tracefork_child (void *arg)
+{
+ ptrace (PTRACE_TRACEME, 0, 0, 0);
+ kill (getpid (), SIGSTOP);
+ clone (linux_tracefork_grandchild, arg, CLONE_VM | SIGCHLD, NULL);
+ _exit (0);
+}
+
+/* Wrapper function for waitpid which handles EINTR. */
+
+static int
+my_waitpid (int pid, int *status, int flags)
+{
+ int ret;
+ do
+ {
+ ret = waitpid (pid, status, flags);
+ }
+ while (ret == -1 && errno == EINTR);
+
+ return ret;
+}
+
+/* Determine if PTRACE_O_TRACEFORK can be used to follow fork events. Make
+ sure that we can enable the option, and that it had the desired
+ effect. */
+
+static void
+linux_test_for_tracefork (void)
+{
+ int child_pid, ret, status;
+ long second_pid;
+ char *stack = malloc (8192);
+
+ linux_supports_tracefork_flag = 0;
+
+ /* Use CLONE_VM instead of fork, to support uClinux (no MMU). */
+ child_pid = clone (linux_tracefork_child, stack + 2048,
+ CLONE_VM | SIGCHLD, stack + 6144);
+ if (child_pid == -1)
+ perror_with_name ("clone");
+
+ ret = my_waitpid (child_pid, &status, 0);
+ if (ret == -1)
+ perror_with_name ("waitpid");
+ else if (ret != child_pid)
+ error ("linux_test_for_tracefork: waitpid: unexpected result %d.", ret);
+ if (! WIFSTOPPED (status))
+ error ("linux_test_for_tracefork: waitpid: unexpected status %d.", status);
+
+ ret = ptrace (PTRACE_SETOPTIONS, child_pid, 0, PTRACE_O_TRACEFORK);
+ if (ret != 0)
+ {
+ ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
+ if (ret != 0)
+ {
+ warning ("linux_test_for_tracefork: failed to kill child");
+ return;
+ }
+
+ ret = my_waitpid (child_pid, &status, 0);
+ if (ret != child_pid)
+ warning ("linux_test_for_tracefork: failed to wait for killed child");
+ else if (!WIFSIGNALED (status))
+ warning ("linux_test_for_tracefork: unexpected wait status 0x%x from "
+ "killed child", status);
+
+ return;
+ }
+
+ ret = ptrace (PTRACE_CONT, child_pid, 0, 0);
+ if (ret != 0)
+ warning ("linux_test_for_tracefork: failed to resume child");
+
+ ret = my_waitpid (child_pid, &status, 0);
+
+ if (ret == child_pid && WIFSTOPPED (status)
+ && status >> 16 == PTRACE_EVENT_FORK)
+ {
+ second_pid = 0;
+ ret = ptrace (PTRACE_GETEVENTMSG, child_pid, 0, &second_pid);
+ if (ret == 0 && second_pid != 0)
+ {
+ int second_status;
+
+ linux_supports_tracefork_flag = 1;
+ my_waitpid (second_pid, &second_status, 0);
+ ret = ptrace (PTRACE_KILL, second_pid, 0, 0);
+ if (ret != 0)
+ warning ("linux_test_for_tracefork: failed to kill second child");
+ my_waitpid (second_pid, &status, 0);
+ }
+ }
+ else
+ warning ("linux_test_for_tracefork: unexpected result from waitpid "
+ "(%d, status 0x%x)", ret, status);
+
+ do
+ {
+ ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
+ if (ret != 0)
+ warning ("linux_test_for_tracefork: failed to kill child");
+ my_waitpid (child_pid, &status, 0);
+ }
+ while (WIFSTOPPED (status));
+
+ free (stack);
+}
+
+
static void
linux_look_up_symbols (void)
{
#ifdef USE_THREAD_DB
- if (using_threads)
+ if (thread_db_active)
return;
- using_threads = thread_db_init ();
+ thread_db_active = thread_db_init (!linux_supports_tracefork_flag);
#endif
}
static void
-linux_send_signal (int signum)
+linux_request_interrupt (void)
{
extern unsigned long signal_pid;
struct process_info *process;
process = get_thread_process (current_inferior);
- kill_lwp (process->lwpid, signum);
+ kill_lwp (process->lwpid, SIGINT);
}
else
- kill_lwp (signal_pid, signum);
+ kill_lwp (signal_pid, SIGINT);
}
/* Copy LEN bytes from inferior's auxiliary vector starting at OFFSET
return 0;
}
-#if defined(__UCLIBC__) && !defined(__UCLIBC_HAS_MMU__)
+#if defined(__UCLIBC__) && defined(HAS_NOMMU)
#if defined(__mcoldfire__)
/* These should really be defined in the kernel's ptrace.h header. */
#define PT_TEXT_ADDR 49*4
}
#endif
+static const char *
+linux_arch_string (void)
+{
+ return the_low_target.arch_string;
+}
+
static struct target_ops linux_target_ops = {
linux_create_inferior,
linux_attach,
linux_kill,
linux_detach,
+ linux_join,
linux_thread_alive,
linux_resume,
linux_wait,
linux_read_memory,
linux_write_memory,
linux_look_up_symbols,
- linux_send_signal,
+ linux_request_interrupt,
linux_read_auxv,
linux_insert_watchpoint,
linux_remove_watchpoint,
linux_stopped_by_watchpoint,
linux_stopped_data_address,
-#if defined(__UCLIBC__) && !defined(__UCLIBC_HAS_MMU__)
+#if defined(__UCLIBC__) && defined(HAS_NOMMU)
linux_read_offsets,
#else
NULL,
#else
NULL,
#endif
+ linux_arch_string,
};
static void
void
initialize_low (void)
{
- using_threads = 0;
+ thread_db_active = 0;
set_target_ops (&linux_target_ops);
set_breakpoint_data (the_low_target.breakpoint,
the_low_target.breakpoint_len);
init_registers ();
linux_init_signals ();
+ linux_test_for_tracefork ();
}
projects / deliverable / binutils-gdb.git / blobdiff