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* fileio.c (CHECK_LENGTH): New macro.

Browse source 
(Fexpand_file_name): Use it and get rid of a few more calls
to strlen and strcat.
This commit is contained in:
Dmitry Antipov 2014-09-02 09:44:38 +04:00
parent 068c8b7d6a
commit a4a30aa0ec
2 changed files with 37 additions and 15 deletions
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6
src/ChangeLog
View file

@ -1,3 +1,9 @@
2014-09-02 Dmitry Antipov <dmantipov@yandex.ru>
* fileio.c (CHECK_LENGTH): New macro.
(Fexpand_file_name): Use it and get rid of a few more calls
to strlen and strcat.
2014-09-01 Dmitry Antipov <dmantipov@yandex.ru>
Avoid extra calls to strlen in filesystem I/O routines.

46
src/fileio.c
View file

@ -847,8 +847,15 @@ probably use `make-temp-file' instead, except in three circumstances:
return make_temp_name (prefix, 0);
}
/* The following function does a lot of work with \0-terminated strings.
To avoid extra calls to strlen and strcat, we maintain an important
lengths explicitly. This macro is used to check whether we're in sync. */
#ifdef ENABLE_CHECKING
#define CHECK_LENGTH(str, len) (eassert (strlen (str) == len), len)
#else
#define CHECK_LENGTH(str, len) (len)
#endif /* ENABLE_CHECKING */
DEFUN ("expand-file-name", Fexpand_file_name, Sexpand_file_name, 1, 2, 0,
doc: /* Convert filename NAME to absolute, and canonicalize it.
Second arg DEFAULT-DIRECTORY is directory to start with if NAME is relative
@ -889,7 +896,7 @@ filesystem tree, not (expand-file-name ".." dirname). */)
bool collapse_newdir = 1;
bool is_escaped = 0;
#endif /* DOS_NT */
ptrdiff_t length, newdirlen;
ptrdiff_t length, newdirlen, nmlen, nbytes;
Lisp_Object handler, result, handled_name;
bool multibyte;
Lisp_Object hdir;
@ -1018,14 +1025,16 @@ filesystem tree, not (expand-file-name ".." dirname). */)
default_directory = Fdowncase (default_directory);
#endif
/* Make a local copy of nm[] to protect it from GC in DECODE_FILE below. */
/* Make a local copy of NAME to protect it from GC in DECODE_FILE below. */
nm = xlispstrdupa (name);
nmlen = SBYTES (name);
#ifdef DOS_NT
/* Note if special escape prefix is present, but remove for now. */
if (nm[0] == '/' && nm[1] == ':')
{
is_escaped = 1;
nmlen -= 2;
nm += 2;
}
@ -1035,6 +1044,7 @@ filesystem tree, not (expand-file-name ".." dirname). */)
if (IS_DRIVE (nm[0]) && IS_DEVICE_SEP (nm[1]))
{
drive = (unsigned char) nm[0];
nmlen -= 2;
nm += 2;
}
@ -1043,7 +1053,7 @@ filesystem tree, not (expand-file-name ".." dirname). */)
colon when stripping the drive letter. Otherwise, this expands to
"//somedir". */
if (drive && IS_DIRECTORY_SEP (nm[0]) && IS_DIRECTORY_SEP (nm[1]))
nm++;
nmlen--, nm++;
/* Discard any previous drive specifier if nm is now in UNC format. */
if (IS_DIRECTORY_SEP (nm[0]) && IS_DIRECTORY_SEP (nm[1])
@ -1104,7 +1114,8 @@ filesystem tree, not (expand-file-name ".." dirname). */)
if (IS_DIRECTORY_SEP (nm[1]))
{
if (strcmp (nm, SSDATA (name)) != 0)
name = make_specified_string (nm, -1, strlen (nm), multibyte);
name = make_specified_string
(nm, -1, CHECK_LENGTH (nm, nmlen), multibyte);
}
else
#endif
@ -1125,7 +1136,8 @@ filesystem tree, not (expand-file-name ".." dirname). */)
#else /* not DOS_NT */
if (strcmp (nm, SSDATA (name)) == 0)
return name;
return make_specified_string (nm, -1, strlen (nm), multibyte);
return make_specified_string
(nm, -1, CHECK_LENGTH (nm, nmlen), multibyte);
#endif /* not DOS_NT */
}
}
@ -1158,7 +1170,7 @@ filesystem tree, not (expand-file-name ".." dirname). */)
if (!(newdir = egetenv ("HOME")))
newdir = "";
nm++;
nmlen--, nm++;
/* `egetenv' may return a unibyte string, which will bite us since
we expect the directory to be multibyte. */
#ifdef WINDOWSNT
@ -1211,6 +1223,7 @@ filesystem tree, not (expand-file-name ".." dirname). */)
newdir = SSDATA (hdir);
newdirlen = SBYTES (hdir);
}
nmlen -= (p - nm);
nm = p;
#ifdef DOS_NT
collapse_newdir = 0;
@ -1320,9 +1333,11 @@ filesystem tree, not (expand-file-name ".." dirname). */)
if (!IS_DIRECTORY_SEP (nm[0]))
{
char *tmp = alloca (newdirlen + file_name_as_directory_slop
+ strlen (nm) + 1);
file_name_as_directory (tmp, newdir, newdirlen, multibyte);
strcat (tmp, nm);
+ CHECK_LENGTH (nm, nmlen) + 1);
nbytes = file_name_as_directory (tmp, newdir, newdirlen,
multibyte);
memcpy (tmp + nbytes, nm, nmlen + 1);
nmlen += nbytes;
nm = tmp;
}
adir = alloca (adir_size);
@ -1382,8 +1397,7 @@ filesystem tree, not (expand-file-name ".." dirname). */)
{
/* Ignore any slash at the end of newdir, unless newdir is
just "/" or "//". */
length = newdirlen;
eassert (length == strlen (newdir));
length = CHECK_LENGTH (newdir, newdirlen);
while (length > 1 && IS_DIRECTORY_SEP (newdir[length - 1])
&& ! (length == 2 && IS_DIRECTORY_SEP (newdir[0])))
length--;
@ -1392,7 +1406,7 @@ filesystem tree, not (expand-file-name ".." dirname). */)
length = 0;
/* Now concatenate the directory and name to new space in the stack frame. */
tlen = length + file_name_as_directory_slop + strlen (nm) + 1;
tlen = length + file_name_as_directory_slop + CHECK_LENGTH (nm, nmlen) + 1;
#ifdef DOS_NT
/* Reserve space for drive specifier and escape prefix, since either
or both may need to be inserted. (The Microsoft x86 compiler
@ -1403,6 +1417,7 @@ filesystem tree, not (expand-file-name ".." dirname). */)
target = SAFE_ALLOCA (tlen);
#endif /* not DOS_NT */
*target = 0;
nbytes = 0;
if (newdir)
{
@ -1420,13 +1435,14 @@ filesystem tree, not (expand-file-name ".." dirname). */)
{
memcpy (target, newdir, length);
target[length] = 0;
nbytes = length;
}
}
else
file_name_as_directory (target, newdir, length, multibyte);
nbytes = file_name_as_directory (target, newdir, length, multibyte);
}
strcat (target, nm);
memcpy (target + nbytes, nm, nmlen + 1);
/* Now canonicalize by removing `//', `/.' and `/foo/..' if they
appear. */