OpenE2K/binutils-gdb
12
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity
1c1a69dcae
binutils-gdb/libctf/ctf-impl.h
Nick Alcock 9323dd869d libctf: make ctf_dump not crash on OOM 
ctf_dump calls ctf_str_append extensively but never checks to see if it
returns NULL (on OOM).  If it ever does, we truncate the string we are
appending to and leak it!

Instead, create a variant of ctf_str_append that returns the *original
string* on OOM, and use it in ctf-dump.  It is far better to omit a tiny
piece of a dump on OOM than to omit a bigger piece, and it is also
better to do this in what is after all purely debugging code than it is
to uglify ctf-dump.c with huge numbers of checks for the out-of-memory
case.  Slightly truncated debugging output is better than no debugging
output at all and an out-of-memory message.

New in v4.

libctf/
	* ctf-impl.h (ctf_str_append_noerr): Declare.
	* ctf-util.c (ctf_str_append_noerr): Define in terms of
	ctf_str_append.
	* ctf-dump.c (str_append): New, call it.
	(ctf_dump_format_type): Use str_append, not ctf_str_append.
	(ctf_dump_label): Likewise.
	(ctf_dump_objts): Likewise.
	(ctf_dump_funcs): Likewise.
	(ctf_dump_var): Likewise.
	(ctf_dump_member): Likewise.
	(ctf_dump_type): Likewise.
	(ctf_dump): Likewise.
2019-10-03 17:04:56 +01:00

486 lines
20 KiB
C
Raw Blame History

/* Implementation header.
Copyright (C) 2019 Free Software Foundation, Inc.
This file is part of libctf.
libctf 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 3, 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; see the file COPYING. If not see
<http://www.gnu.org/licenses/>. */
#ifndef _CTF_IMPL_H
#define _CTF_IMPL_H
#include "config.h"
#include <errno.h>
#include <sys/param.h>
#include "ctf-decls.h"
#include <ctf-api.h>
#include <sys/types.h>
#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdint.h>
#include <limits.h>
#include <ctype.h>
#include <elf.h>
#include <bfd.h>
#ifdef __cplusplus
extern "C"
{
#endif
/* Compiler attributes. */
#if defined (__GNUC__)
/* GCC. We assume that all compilers claiming to be GCC support sufficiently
many GCC attributes that the code below works. If some non-GCC compilers
masquerading as GCC in fact do not implement these attributes, version checks
may be required. */
/* We use the _libctf_*_ pattern to avoid clashes with any future attribute
macros glibc may introduce, which have names of the pattern
__attribute_blah__. */
#define _libctf_printflike_(string_index,first_to_check) \
__attribute__ ((__format__ (__printf__, (string_index), (first_to_check))))
#define _libctf_unlikely_(x) __builtin_expect ((x), 0)
#define _libctf_unused_ __attribute__ ((__unused__))
#define _libctf_malloc_ __attribute__((__malloc__))
#endif
/* libctf in-memory state. */
typedef struct ctf_fixed_hash ctf_hash_t; /* Private to ctf-hash.c. */
typedef struct ctf_dynhash ctf_dynhash_t; /* Private to ctf-hash.c. */
typedef struct ctf_strs
{
const char *cts_strs; /* Base address of string table. */
size_t cts_len; /* Size of string table in bytes. */
} ctf_strs_t;
typedef struct ctf_strs_writable
{
char *cts_strs; /* Base address of string table. */
size_t cts_len; /* Size of string table in bytes. */
} ctf_strs_writable_t;
typedef struct ctf_dmodel
{
const char *ctd_name; /* Data model name. */
int ctd_code; /* Data model code. */
size_t ctd_pointer; /* Size of void * in bytes. */
size_t ctd_char; /* Size of char in bytes. */
size_t ctd_short; /* Size of short in bytes. */
size_t ctd_int; /* Size of int in bytes. */
size_t ctd_long; /* Size of long in bytes. */
} ctf_dmodel_t;
typedef struct ctf_names
{
ctf_hash_t *ctn_readonly; /* Hash table when readonly. */
ctf_dynhash_t *ctn_writable; /* Hash table when writable. */
} ctf_names_t;
typedef struct ctf_lookup
{
const char *ctl_prefix; /* String prefix for this lookup. */
size_t ctl_len; /* Length of prefix string in bytes. */
ctf_names_t *ctl_hash; /* Pointer to hash table for lookup. */
} ctf_lookup_t;
typedef struct ctf_fileops
{
uint32_t (*ctfo_get_kind) (uint32_t);
uint32_t (*ctfo_get_root) (uint32_t);
uint32_t (*ctfo_get_vlen) (uint32_t);
ssize_t (*ctfo_get_ctt_size) (const ctf_file_t *, const ctf_type_t *,
ssize_t *, ssize_t *);
ssize_t (*ctfo_get_vbytes) (unsigned short, ssize_t, size_t);
} ctf_fileops_t;
typedef struct ctf_list
{
struct ctf_list *l_prev; /* Previous pointer or tail pointer. */
struct ctf_list *l_next; /* Next pointer or head pointer. */
} ctf_list_t;
typedef enum
{
CTF_PREC_BASE,
CTF_PREC_POINTER,
CTF_PREC_ARRAY,
CTF_PREC_FUNCTION,
CTF_PREC_MAX
} ctf_decl_prec_t;
typedef struct ctf_decl_node
{
ctf_list_t cd_list; /* Linked list pointers. */
ctf_id_t cd_type; /* Type identifier. */
uint32_t cd_kind; /* Type kind. */
uint32_t cd_n; /* Type dimension if array. */
} ctf_decl_node_t;
typedef struct ctf_decl
{
ctf_list_t cd_nodes[CTF_PREC_MAX]; /* Declaration node stacks. */
int cd_order[CTF_PREC_MAX]; /* Storage order of decls. */
ctf_decl_prec_t cd_qualp; /* Qualifier precision. */
ctf_decl_prec_t cd_ordp; /* Ordered precision. */
char *cd_buf; /* Buffer for output. */
int cd_err; /* Saved error value. */
int cd_enomem; /* Nonzero if OOM during printing. */
} ctf_decl_t;
typedef struct ctf_dmdef
{
ctf_list_t dmd_list; /* List forward/back pointers. */
char *dmd_name; /* Name of this member. */
ctf_id_t dmd_type; /* Type of this member (for sou). */
unsigned long dmd_offset; /* Offset of this member in bits (for sou). */
int dmd_value; /* Value of this member (for enum). */
} ctf_dmdef_t;
typedef struct ctf_dtdef
{
ctf_list_t dtd_list; /* List forward/back pointers. */
ctf_id_t dtd_type; /* Type identifier for this definition. */
ctf_type_t dtd_data; /* Type node, including name. */
union
{
ctf_list_t dtu_members; /* struct, union, or enum */
ctf_arinfo_t dtu_arr; /* array */
ctf_encoding_t dtu_enc; /* integer or float */
ctf_id_t *dtu_argv; /* function */
ctf_slice_t dtu_slice; /* slice */
} dtd_u;
} ctf_dtdef_t;
typedef struct ctf_dvdef
{
ctf_list_t dvd_list; /* List forward/back pointers. */
char *dvd_name; /* Name associated with variable. */
ctf_id_t dvd_type; /* Type of variable. */
unsigned long dvd_snapshots; /* Snapshot count when inserted. */
} ctf_dvdef_t;
typedef struct ctf_bundle
{
ctf_file_t *ctb_file; /* CTF container handle. */
ctf_id_t ctb_type; /* CTF type identifier. */
ctf_dtdef_t *ctb_dtd; /* CTF dynamic type definition (if any). */
} ctf_bundle_t;
/* Atoms associate strings with a list of the CTF items that reference that
string, so that ctf_update() can instantiate all the strings using the
ctf_str_atoms and then reassociate them with the real string later.
Strings can be interned into ctf_str_atom without having refs associated
with them, for values that are returned to callers, etc. Items are only
removed from this table on ctf_close(), but on every ctf_update(), all the
csa_refs in all entries are purged. */
typedef struct ctf_str_atom
{
const char *csa_str; /* Backpointer to string (hash key). */
ctf_list_t csa_refs; /* This string's refs. */
uint32_t csa_offset; /* Strtab offset, if any. */
uint32_t csa_external_offset; /* External strtab offset, if any. */
unsigned long csa_snapshot_id; /* Snapshot ID at time of creation. */
} ctf_str_atom_t;
/* The refs of a single string in the atoms table. */
typedef struct ctf_str_atom_ref
{
ctf_list_t caf_list; /* List forward/back pointers. */
uint32_t *caf_ref; /* A single ref to this string. */
} ctf_str_atom_ref_t;
/* The structure used as the key in a ctf_link_type_mapping, which lets the
linker machinery determine which type IDs on the input side of a link map to
which types on the output side. (The value is a ctf_id_t: another
index, not a type.) */
typedef struct ctf_link_type_mapping_key
{
ctf_file_t *cltm_fp;
ctf_id_t cltm_idx;
} ctf_link_type_mapping_key_t;
/* The ctf_file is the structure used to represent a CTF container to library
clients, who see it only as an opaque pointer. Modifications can therefore
be made freely to this structure without regard to client versioning. The
ctf_file_t typedef appears in <ctf-api.h> and declares a forward tag.
NOTE: ctf_update() requires that everything inside of ctf_file either be an
immediate value, a pointer to dynamically allocated data *outside* of the
ctf_file itself, or a pointer to statically allocated data. If you add a
pointer to ctf_file that points to something within the ctf_file itself,
you must make corresponding changes to ctf_update(). */
struct ctf_file
{
const ctf_fileops_t *ctf_fileops; /* Version-specific file operations. */
struct ctf_header *ctf_header; /* The header from this CTF file. */
unsigned char ctf_openflags; /* Flags the file had when opened. */
ctf_sect_t ctf_data; /* CTF data from object file. */
ctf_sect_t ctf_symtab; /* Symbol table from object file. */
ctf_sect_t ctf_strtab; /* String table from object file. */
ctf_dynhash_t *ctf_prov_strtab; /* Maps provisional-strtab offsets
to names. */
ctf_dynhash_t *ctf_syn_ext_strtab; /* Maps ext-strtab offsets to names. */
void *ctf_data_mmapped; /* CTF data we mmapped, to free later. */
size_t ctf_data_mmapped_len; /* Length of CTF data we mmapped. */
ctf_names_t ctf_structs; /* Hash table of struct types. */
ctf_names_t ctf_unions; /* Hash table of union types. */
ctf_names_t ctf_enums; /* Hash table of enum types. */
ctf_names_t ctf_names; /* Hash table of remaining type names. */
ctf_lookup_t ctf_lookups[5]; /* Pointers to nametabs for name lookup. */
ctf_strs_t ctf_str[2]; /* Array of string table base and bounds. */
ctf_dynhash_t *ctf_str_atoms; /* Hash table of ctf_str_atoms_t. */
uint64_t ctf_str_num_refs; /* Number of refs to cts_str_atoms. */
uint32_t ctf_str_prov_offset; /* Latest provisional offset assigned so far. */
unsigned char *ctf_base; /* CTF file pointer. */
unsigned char *ctf_dynbase; /* Freeable CTF file pointer. */
unsigned char *ctf_buf; /* Uncompressed CTF data buffer. */
size_t ctf_size; /* Size of CTF header + uncompressed data. */
uint32_t *ctf_sxlate; /* Translation table for symtab entries. */
unsigned long ctf_nsyms; /* Number of entries in symtab xlate table. */
uint32_t *ctf_txlate; /* Translation table for type IDs. */
uint32_t *ctf_ptrtab; /* Translation table for pointer-to lookups. */
size_t ctf_ptrtab_len; /* Num types storable in ptrtab currently. */
struct ctf_varent *ctf_vars; /* Sorted variable->type mapping. */
unsigned long ctf_nvars; /* Number of variables in ctf_vars. */
unsigned long ctf_typemax; /* Maximum valid type ID number. */
const ctf_dmodel_t *ctf_dmodel; /* Data model pointer (see above). */
const char *ctf_cuname; /* Compilation unit name (if any). */
char *ctf_dyncuname; /* Dynamically allocated name of CU. */
struct ctf_file *ctf_parent; /* Parent CTF container (if any). */
const char *ctf_parlabel; /* Label in parent container (if any). */
const char *ctf_parname; /* Basename of parent (if any). */
char *ctf_dynparname; /* Dynamically allocated name of parent. */
uint32_t ctf_parmax; /* Highest type ID of a parent type. */
uint32_t ctf_refcnt; /* Reference count (for parent links). */
uint32_t ctf_flags; /* Libctf flags (see below). */
int ctf_errno; /* Error code for most recent error. */
int ctf_version; /* CTF data version. */
ctf_dynhash_t *ctf_dthash; /* Hash of dynamic type definitions. */
ctf_list_t ctf_dtdefs; /* List of dynamic type definitions. */
ctf_dynhash_t *ctf_dvhash; /* Hash of dynamic variable mappings. */
ctf_list_t ctf_dvdefs; /* List of dynamic variable definitions. */
unsigned long ctf_dtoldid; /* Oldest id that has been committed. */
unsigned long ctf_snapshots; /* ctf_snapshot() plus ctf_update() count. */
unsigned long ctf_snapshot_lu; /* ctf_snapshot() call count at last update. */
ctf_archive_t *ctf_archive; /* Archive this ctf_file_t came from. */
ctf_dynhash_t *ctf_link_inputs; /* Inputs to this link. */
ctf_dynhash_t *ctf_link_outputs; /* Additional outputs from this link. */
ctf_dynhash_t *ctf_link_type_mapping; /* Map input types to output types. */
ctf_dynhash_t *ctf_link_cu_mapping; /* Map CU names to CTF dict names. */
/* Allow the caller to Change the name of link archive members. */
ctf_link_memb_name_changer_f *ctf_link_memb_name_changer;
void *ctf_link_memb_name_changer_arg; /* Argument for it. */
ctf_dynhash_t *ctf_add_processing; /* Types ctf_add_type is working on now. */
char *ctf_tmp_typeslice; /* Storage for slicing up type names. */
size_t ctf_tmp_typeslicelen; /* Size of the typeslice. */
void *ctf_specific; /* Data for ctf_get/setspecific(). */
};
/* An abstraction over both a ctf_file_t and a ctf_archive_t. */
struct ctf_archive_internal
{
int ctfi_is_archive;
ctf_file_t *ctfi_file;
struct ctf_archive *ctfi_archive;
ctf_sect_t ctfi_symsect;
ctf_sect_t ctfi_strsect;
void *ctfi_data;
bfd *ctfi_abfd; /* Optional source of section data. */
void (*ctfi_bfd_close) (struct ctf_archive_internal *);
};
/* Return x rounded up to an alignment boundary.
eg, P2ROUNDUP(0x1234, 0x100) == 0x1300 (0x13*align)
eg, P2ROUNDUP(0x5600, 0x100) == 0x5600 (0x56*align) */
#define P2ROUNDUP(x, align) (-(-(x) & -(align)))
/* * If an offs is not aligned already then round it up and align it. */
#define LCTF_ALIGN_OFFS(offs, align) ((offs + (align - 1)) & ~(align - 1))
#define LCTF_TYPE_ISPARENT(fp, id) ((id) <= fp->ctf_parmax)
#define LCTF_TYPE_ISCHILD(fp, id) ((id) > fp->ctf_parmax)
#define LCTF_TYPE_TO_INDEX(fp, id) ((id) & (fp->ctf_parmax))
#define LCTF_INDEX_TO_TYPE(fp, id, child) (child ? ((id) | (fp->ctf_parmax+1)) : \
(id))
#define LCTF_INDEX_TO_TYPEPTR(fp, i) \
((fp->ctf_flags & LCTF_RDWR) ? \
&(ctf_dtd_lookup (fp, LCTF_INDEX_TO_TYPE \
(fp, i, fp->ctf_flags & LCTF_CHILD))->dtd_data) : \
(ctf_type_t *)((uintptr_t)(fp)->ctf_buf + (fp)->ctf_txlate[(i)]))
#define LCTF_INFO_KIND(fp, info) ((fp)->ctf_fileops->ctfo_get_kind(info))
#define LCTF_INFO_ISROOT(fp, info) ((fp)->ctf_fileops->ctfo_get_root(info))
#define LCTF_INFO_VLEN(fp, info) ((fp)->ctf_fileops->ctfo_get_vlen(info))
#define LCTF_VBYTES(fp, kind, size, vlen) \
((fp)->ctf_fileops->ctfo_get_vbytes(kind, size, vlen))
static inline ssize_t ctf_get_ctt_size (const ctf_file_t *fp,
const ctf_type_t *tp,
ssize_t *sizep,
ssize_t *incrementp)
{
return (fp->ctf_fileops->ctfo_get_ctt_size (fp, tp, sizep, incrementp));
}
#define LCTF_CHILD 0x0001 /* CTF container is a child */
#define LCTF_RDWR 0x0002 /* CTF container is writable */
#define LCTF_DIRTY 0x0004 /* CTF container has been modified */
extern ctf_names_t *ctf_name_table (ctf_file_t *, int);
extern const ctf_type_t *ctf_lookup_by_id (ctf_file_t **, ctf_id_t);
extern ctf_id_t ctf_lookup_by_rawname (ctf_file_t *, int, const char *);
extern ctf_id_t ctf_lookup_by_rawhash (ctf_file_t *, ctf_names_t *, const char *);
extern void ctf_set_ctl_hashes (ctf_file_t *);
typedef unsigned int (*ctf_hash_fun) (const void *ptr);
extern unsigned int ctf_hash_integer (const void *ptr);
extern unsigned int ctf_hash_string (const void *ptr);
extern unsigned int ctf_hash_type_mapping_key (const void *ptr);
typedef int (*ctf_hash_eq_fun) (const void *, const void *);
extern int ctf_hash_eq_integer (const void *, const void *);
extern int ctf_hash_eq_string (const void *, const void *);
extern int ctf_hash_eq_type_mapping_key (const void *, const void *);
typedef void (*ctf_hash_free_fun) (void *);
typedef void (*ctf_hash_iter_f) (void *key, void *value, void *arg);
typedef int (*ctf_hash_iter_remove_f) (void *key, void *value, void *arg);
extern ctf_hash_t *ctf_hash_create (unsigned long, ctf_hash_fun, ctf_hash_eq_fun);
extern int ctf_hash_insert_type (ctf_hash_t *, ctf_file_t *, uint32_t, uint32_t);
extern int ctf_hash_define_type (ctf_hash_t *, ctf_file_t *, uint32_t, uint32_t);
extern ctf_id_t ctf_hash_lookup_type (ctf_hash_t *, ctf_file_t *, const char *);
extern uint32_t ctf_hash_size (const ctf_hash_t *);
extern void ctf_hash_destroy (ctf_hash_t *);
extern ctf_dynhash_t *ctf_dynhash_create (ctf_hash_fun, ctf_hash_eq_fun,
ctf_hash_free_fun, ctf_hash_free_fun);
extern int ctf_dynhash_insert (ctf_dynhash_t *, void *, void *);
extern void ctf_dynhash_remove (ctf_dynhash_t *, const void *);
extern void ctf_dynhash_empty (ctf_dynhash_t *);
extern void *ctf_dynhash_lookup (ctf_dynhash_t *, const void *);
extern void ctf_dynhash_destroy (ctf_dynhash_t *);
extern void ctf_dynhash_iter (ctf_dynhash_t *, ctf_hash_iter_f, void *);
extern void ctf_dynhash_iter_remove (ctf_dynhash_t *, ctf_hash_iter_remove_f,
void *);
#define ctf_list_prev(elem) ((void *)(((ctf_list_t *)(elem))->l_prev))
#define ctf_list_next(elem) ((void *)(((ctf_list_t *)(elem))->l_next))
extern void ctf_list_append (ctf_list_t *, void *);
extern void ctf_list_prepend (ctf_list_t *, void *);
extern void ctf_list_delete (ctf_list_t *, void *);
extern int ctf_list_empty_p (ctf_list_t *lp);
extern int ctf_dtd_insert (ctf_file_t *, ctf_dtdef_t *, int);
extern void ctf_dtd_delete (ctf_file_t *, ctf_dtdef_t *);
extern ctf_dtdef_t *ctf_dtd_lookup (const ctf_file_t *, ctf_id_t);
extern ctf_dtdef_t *ctf_dynamic_type (const ctf_file_t *, ctf_id_t);
extern int ctf_dvd_insert (ctf_file_t *, ctf_dvdef_t *);
extern void ctf_dvd_delete (ctf_file_t *, ctf_dvdef_t *);
extern ctf_dvdef_t *ctf_dvd_lookup (const ctf_file_t *, const char *);
extern void ctf_add_type_mapping (ctf_file_t *src_fp, ctf_id_t src_type,
ctf_file_t *dst_fp, ctf_id_t dst_type);
extern ctf_id_t ctf_type_mapping (ctf_file_t *src_fp, ctf_id_t src_type,
ctf_file_t **dst_fp);
extern void ctf_decl_init (ctf_decl_t *);
extern void ctf_decl_fini (ctf_decl_t *);
extern void ctf_decl_push (ctf_decl_t *, ctf_file_t *, ctf_id_t);
_libctf_printflike_ (2, 3)
extern void ctf_decl_sprintf (ctf_decl_t *, const char *, ...);
extern char *ctf_decl_buf (ctf_decl_t *cd);
extern const char *ctf_strptr (ctf_file_t *, uint32_t);
extern const char *ctf_strraw (ctf_file_t *, uint32_t);
extern const char *ctf_strraw_explicit (ctf_file_t *, uint32_t,
ctf_strs_t *);
extern int ctf_str_create_atoms (ctf_file_t *);
extern void ctf_str_free_atoms (ctf_file_t *);
extern uint32_t ctf_str_add (ctf_file_t *, const char *);
extern uint32_t ctf_str_add_ref (ctf_file_t *, const char *, uint32_t *ref);
extern int ctf_str_add_external (ctf_file_t *, const char *, uint32_t offset);
extern void ctf_str_remove_ref (ctf_file_t *, const char *, uint32_t *ref);
extern void ctf_str_rollback (ctf_file_t *, ctf_snapshot_id_t);
extern void ctf_str_purge_refs (ctf_file_t *);
extern ctf_strs_writable_t ctf_str_write_strtab (ctf_file_t *);
extern struct ctf_archive *ctf_arc_open_internal (const char *, int *);
extern struct ctf_archive *ctf_arc_bufopen (const void *, size_t, int *);
extern void ctf_arc_close_internal (struct ctf_archive *);
extern void *ctf_set_open_errno (int *, int);
extern unsigned long ctf_set_errno (ctf_file_t *, int);
extern ctf_file_t *ctf_simple_open_internal (const char *, size_t, const char *,
size_t, size_t,
const char *, size_t,
ctf_dynhash_t *, int, int *);
extern ctf_file_t *ctf_bufopen_internal (const ctf_sect_t *, const ctf_sect_t *,
const ctf_sect_t *, ctf_dynhash_t *,
int, int *);
extern int ctf_serialize (ctf_file_t *);
_libctf_malloc_
extern void *ctf_mmap (size_t length, size_t offset, int fd);
extern void ctf_munmap (void *, size_t);
extern ssize_t ctf_pread (int fd, void *buf, ssize_t count, off_t offset);
extern void *ctf_realloc (ctf_file_t *, void *, size_t);
extern char *ctf_str_append (char *, const char *);
extern char *ctf_str_append_noerr (char *, const char *);
extern const char *ctf_strerror (int);
extern ctf_id_t ctf_type_resolve_unsliced (ctf_file_t *, ctf_id_t);
extern int ctf_type_kind_unsliced (ctf_file_t *, ctf_id_t);
_libctf_printflike_ (1, 2)
extern void ctf_dprintf (const char *, ...);
extern void libctf_init_debug (void);
extern Elf64_Sym *ctf_sym_to_elf64 (const Elf32_Sym *src, Elf64_Sym *dst);
extern const char *ctf_lookup_symbol_name (ctf_file_t *fp, unsigned long symidx);
/* Variables, all underscore-prepended. */
extern const char _CTF_SECTION[]; /* name of CTF ELF section */
extern const char _CTF_NULLSTR[]; /* empty string */
extern int _libctf_version; /* library client version */
extern int _libctf_debug; /* debugging messages enabled */
#ifdef __cplusplus
}
#endif
#endif /* _CTF_IMPL_H */
Reference in New Issue View Git Blame Copy Permalink