* [PATCH v4 1/2] add internal aliases __opendir, __readdir and __closedir
@ 2019-09-06 19:40 Ismael Luceno
2019-09-06 19:40 ` [PATCH v4 2/2] glob: implement GLOB_ALTDIRFUNC et al Ismael Luceno
0 siblings, 1 reply; 3+ messages in thread
From: Ismael Luceno @ 2019-09-06 19:40 UTC (permalink / raw)
To: musl; +Cc: Ismael Luceno
Signed-off-by: Ismael Luceno <ismael@iodev.co.uk>
---
src/dirent/closedir.c | 4 +++-
src/dirent/opendir.c | 4 +++-
src/dirent/readdir.c | 5 +++--
src/include/dirent.h | 10 ++++++++++
4 files changed, 19 insertions(+), 4 deletions(-)
create mode 100644 src/include/dirent.h
diff --git a/src/dirent/closedir.c b/src/dirent/closedir.c
index e794ae9ca44b..f4249f56e210 100644
--- a/src/dirent/closedir.c
+++ b/src/dirent/closedir.c
@@ -3,9 +3,11 @@
#include <stdlib.h>
#include "__dirent.h"
-int closedir(DIR *dir)
+int __closedir(DIR *dir)
{
int ret = close(dir->fd);
free(dir);
return ret;
}
+
+weak_alias(__closedir, closedir);
diff --git a/src/dirent/opendir.c b/src/dirent/opendir.c
index 5cb84e303fee..4123c81994cd 100644
--- a/src/dirent/opendir.c
+++ b/src/dirent/opendir.c
@@ -5,7 +5,7 @@
#include "__dirent.h"
#include "syscall.h"
-DIR *opendir(const char *name)
+DIR *__opendir(const char *name)
{
int fd;
DIR *dir;
@@ -19,3 +19,5 @@ DIR *opendir(const char *name)
dir->fd = fd;
return dir;
}
+
+weak_alias(__opendir, opendir);
diff --git a/src/dirent/readdir.c b/src/dirent/readdir.c
index 569fc7057737..cb34a258569c 100644
--- a/src/dirent/readdir.c
+++ b/src/dirent/readdir.c
@@ -7,7 +7,7 @@
typedef char dirstream_buf_alignment_check[1-2*(int)(
offsetof(struct __dirstream, buf) % sizeof(off_t))];
-struct dirent *readdir(DIR *dir)
+struct dirent *__readdir(DIR *dir)
{
struct dirent *de;
@@ -26,4 +26,5 @@ struct dirent *readdir(DIR *dir)
return de;
}
-weak_alias(readdir, readdir64);
+weak_alias(__readdir, readdir64);
+weak_alias(__readdir, readdir);
diff --git a/src/include/dirent.h b/src/include/dirent.h
new file mode 100644
index 000000000000..918e123566d4
--- /dev/null
+++ b/src/include/dirent.h
@@ -0,0 +1,10 @@
+#ifndef DIRENT_H
+#define DIRENT_H
+
+#include "../../include/dirent.h"
+
+hidden int __closedir(DIR *);
+hidden DIR *__opendir(const char *);
+hidden struct dirent *__readdir(DIR *);
+
+#endif
--
2.23.0
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH v4 2/2] glob: implement GLOB_ALTDIRFUNC et al
2019-09-06 19:40 [PATCH v4 1/2] add internal aliases __opendir, __readdir and __closedir Ismael Luceno
@ 2019-09-06 19:40 ` Ismael Luceno
2019-09-06 21:42 ` Rich Felker
0 siblings, 1 reply; 3+ messages in thread
From: Ismael Luceno @ 2019-09-06 19:40 UTC (permalink / raw)
To: musl; +Cc: Ismael Luceno
Signed-off-by: Ismael Luceno <ismael@iodev.co.uk>
---
Notes:
Changes since v3:
- Wrap pointers used by GLOB_ALTDIRFUNC on the header to protect from namespace
contamination. GNU and BSD code shouldn't be using "dirent", so it should be
safe.
Changes since v2:
- Rebased
Changes since v1:
- Avoid overwriting the function pointers in glob_t
- Wrap {open,read}dir too
include/glob.h | 10 ++++++++++
src/regex/glob.c | 47 +++++++++++++++++++++++++++++++++++++----------
2 files changed, 47 insertions(+), 10 deletions(-)
diff --git a/include/glob.h b/include/glob.h
index 0ff70bdfeef2..26ea65cd1097 100644
--- a/include/glob.h
+++ b/include/glob.h
@@ -16,7 +16,16 @@ typedef struct {
char **gl_pathv;
size_t gl_offs;
int __dummy1;
+
+#if defined(_BSD_SOURCE) || defined(_GNU_SOURCE)
+ void (*gl_closedir)(void *);
+ struct dirent *(*gl_readdir)(void *);
+ void *(*gl_opendir)(const char *);
+ int (*gl_lstat)(const char *__restrict, struct stat *__restrict);
+ int (*gl_stat)(const char *__restrict, struct stat *__restrict);
+#else
void *__dummy2[5];
+#endif
} glob_t;
int glob(const char *__restrict, int, int (*)(const char *, int), glob_t *__restrict);
@@ -31,6 +40,7 @@ void globfree(glob_t *);
#define GLOB_NOESCAPE 0x40
#define GLOB_PERIOD 0x80
+#define GLOB_ALTDIRFUNC 0x0200
#define GLOB_NOMAGIC 0x0800
#define GLOB_TILDE 0x1000
#define GLOB_TILDE_CHECK 0x4000
diff --git a/src/regex/glob.c b/src/regex/glob.c
index 7780e21ee113..4f329f053fe0 100644
--- a/src/regex/glob.c
+++ b/src/regex/glob.c
@@ -1,7 +1,7 @@
#define _BSD_SOURCE
+#include <sys/stat.h>
#include <glob.h>
#include <fnmatch.h>
-#include <sys/stat.h>
#include <dirent.h>
#include <limits.h>
#include <string.h>
@@ -11,6 +11,14 @@
#include <unistd.h>
#include <pwd.h>
+struct dirfn {
+ void (*closedir)(void *);
+ struct dirent *(*readdir)(void *);
+ void *(*opendir)(const char *);
+ int (*lstat)(const char *restrict, struct stat *restrict);
+ int (*stat)(const char *restrict, struct stat *restrict);
+};
+
struct match
{
struct match *next;
@@ -32,7 +40,7 @@ static int append(struct match **tail, const char *name, size_t len, int mark)
return 0;
}
-static int do_glob(char *buf, size_t pos, int type, char *pat, int flags, int (*errfunc)(const char *path, int err), struct match **tail)
+static int do_glob(char *buf, size_t pos, int type, char *pat, int flags, int (*errfunc)(const char *path, int err), const struct dirfn * const restrict dirfn, struct match **tail)
{
/* If GLOB_MARK is unused, we don't care about type. */
if (!type && !(flags & GLOB_MARK)) type = DT_REG;
@@ -100,11 +108,11 @@ static int do_glob(char *buf, size_t pos, int type, char *pat, int flags, int (*
* or if that fails, use lstat for determining existence to
* avoid false negatives in the case of broken symlinks. */
struct stat st;
- if ((flags & GLOB_MARK) && (!type||type==DT_LNK) && !stat(buf, &st)) {
+ if ((flags & GLOB_MARK) && (!type||type==DT_LNK) && !dirfn->stat(buf, &st)) {
if (S_ISDIR(st.st_mode)) type = DT_DIR;
else type = DT_REG;
}
- if (!type && lstat(buf, &st)) {
+ if (!type && dirfn->lstat(buf, &st)) {
if (errno!=ENOENT && (errfunc(buf, errno) || (flags & GLOB_ERR)))
return GLOB_ABORTED;
return 0;
@@ -124,7 +132,7 @@ static int do_glob(char *buf, size_t pos, int type, char *pat, int flags, int (*
saved_sep = '\\';
}
}
- DIR *dir = opendir(pos ? buf : ".");
+ DIR *dir = dirfn->opendir(pos ? buf : ".");
if (!dir) {
if (errfunc(buf, errno) || (flags & GLOB_ERR))
return GLOB_ABORTED;
@@ -132,7 +140,7 @@ static int do_glob(char *buf, size_t pos, int type, char *pat, int flags, int (*
}
int old_errno = errno;
struct dirent *de;
- while (errno=0, de=readdir(dir)) {
+ while (errno=0, de=dirfn->readdir(dir)) {
/* Quickly skip non-directories when there's pattern left. */
if (p2 && de->d_type && de->d_type!=DT_DIR && de->d_type!=DT_LNK)
continue;
@@ -157,15 +165,15 @@ static int do_glob(char *buf, size_t pos, int type, char *pat, int flags, int (*
memcpy(buf+pos, de->d_name, l+1);
if (p2) *p2 = saved_sep;
- int r = do_glob(buf, pos+l, de->d_type, p2 ? p2 : "", flags, errfunc, tail);
+ int r = do_glob(buf, pos+l, de->d_type, p2 ? p2 : "", flags, errfunc, dirfn, tail);
if (r) {
- closedir(dir);
+ dirfn->closedir(dir);
return r;
}
}
int readerr = errno;
if (p2) *p2 = saved_sep;
- closedir(dir);
+ dirfn->closedir(dir);
if (readerr && (errfunc(buf, errno) || (flags & GLOB_ERR)))
return GLOB_ABORTED;
errno = old_errno;
@@ -224,6 +232,10 @@ static int expand_tilde(char **pat, char *buf, size_t *pos)
return 0;
}
+static void wrap_closedir(void *p) { __closedir(p); }
+static struct dirent *wrap_readdir(void *d) { return __readdir(d); }
+static void *wrap_opendir(const char *path) { return __opendir(path); }
+
int glob(const char *restrict pat, int flags, int (*errfunc)(const char *path, int err), glob_t *restrict g)
{
struct match head = { .next = NULL }, *tail = &head;
@@ -231,9 +243,24 @@ int glob(const char *restrict pat, int flags, int (*errfunc)(const char *path, i
size_t offs = (flags & GLOB_DOOFFS) ? g->gl_offs : 0;
int error = 0;
char buf[PATH_MAX];
+ struct dirfn dirfn;
if (!errfunc) errfunc = ignore_err;
+ if (flags & GLOB_ALTDIRFUNC) {
+ dirfn.closedir = g->gl_closedir;
+ dirfn.readdir = g->gl_readdir;
+ dirfn.opendir = g->gl_opendir;
+ dirfn.lstat = g->gl_lstat;
+ dirfn.stat = g->gl_stat;
+ } else {
+ dirfn.closedir = wrap_closedir;
+ dirfn.readdir = wrap_readdir;
+ dirfn.opendir = wrap_opendir;
+ dirfn.lstat = lstat;
+ dirfn.stat = stat;
+ }
+
if (!(flags & GLOB_APPEND)) {
g->gl_offs = offs;
g->gl_pathc = 0;
@@ -249,7 +276,7 @@ int glob(const char *restrict pat, int flags, int (*errfunc)(const char *path, i
if ((flags & (GLOB_TILDE | GLOB_TILDE_CHECK)) && *p == '~')
error = expand_tilde(&s, buf, &pos);
if (!error)
- error = do_glob(buf, pos, 0, s, flags, errfunc, &tail);
+ error = do_glob(buf, pos, 0, s, flags, errfunc, &dirfn, &tail);
free(p);
}
--
2.23.0
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v4 2/2] glob: implement GLOB_ALTDIRFUNC et al
2019-09-06 19:40 ` [PATCH v4 2/2] glob: implement GLOB_ALTDIRFUNC et al Ismael Luceno
@ 2019-09-06 21:42 ` Rich Felker
0 siblings, 0 replies; 3+ messages in thread
From: Rich Felker @ 2019-09-06 21:42 UTC (permalink / raw)
To: musl
On Fri, Sep 06, 2019 at 09:40:22PM +0200, Ismael Luceno wrote:
> diff --git a/include/glob.h b/include/glob.h
> index 0ff70bdfeef2..26ea65cd1097 100644
> --- a/include/glob.h
> +++ b/include/glob.h
> @@ -16,7 +16,16 @@ typedef struct {
> char **gl_pathv;
> size_t gl_offs;
> int __dummy1;
> +
> +#if defined(_BSD_SOURCE) || defined(_GNU_SOURCE)
> + void (*gl_closedir)(void *);
> + struct dirent *(*gl_readdir)(void *);
> + void *(*gl_opendir)(const char *);
> + int (*gl_lstat)(const char *__restrict, struct stat *__restrict);
> + int (*gl_stat)(const char *__restrict, struct stat *__restrict);
> +#else
> void *__dummy2[5];
> +#endif
> } glob_t;
I think you need to forward-declare at least struct stat, and possibly
also struct dirent, so that they refer to the same types as the
declarations elsewhere. At least the argument list is a different
scope and declares a *different* struct stat shadowing the file-scope
one if the file-scope one is not already declared.
With the above change and:
> diff --git a/src/regex/glob.c b/src/regex/glob.c
> index 7780e21ee113..4f329f053fe0 100644
> --- a/src/regex/glob.c
> +++ b/src/regex/glob.c
> @@ -1,7 +1,7 @@
> #define _BSD_SOURCE
^^^^^^^^^^^
combined, every use of g->[something] in glob() is now undefined
behavior if the caller was using a standard profile where the
__dummy2-containing version of glob_t above is the one that's used.
That's because it's accessing one struct type via an lvalue of a
different struct type.
> +#include <sys/stat.h>
> #include <glob.h>
> #include <fnmatch.h>
> -#include <sys/stat.h>
Unrelated: this change is gratuitous.
> @@ -224,6 +232,10 @@ static int expand_tilde(char **pat, char *buf, size_t *pos)
> return 0;
> }
>
> +static void wrap_closedir(void *p) { __closedir(p); }
> +static struct dirent *wrap_readdir(void *d) { return __readdir(d); }
> +static void *wrap_opendir(const char *path) { return __opendir(path); }
> +
> int glob(const char *restrict pat, int flags, int (*errfunc)(const char *path, int err), glob_t *restrict g)
> {
> struct match head = { .next = NULL }, *tail = &head;
> @@ -231,9 +243,24 @@ int glob(const char *restrict pat, int flags, int (*errfunc)(const char *path, i
> size_t offs = (flags & GLOB_DOOFFS) ? g->gl_offs : 0;
^^^^^^^^^^
These are the accesses that become UB. To make them well-defined,
they'd need to be something like G(g,gl_offs), where
#define G(g,m) (*(1?(void*)((char*)(g)+offsetof(glob_t,m)):&((glob_t){0}).m)
is the cleanest abstraction I can think of for the monstrosity needed
to access "something layout-compatible with glob_t, but not glob_t, at
address g".
Imposing this ugliness to avoid UB is part of why I'm hesitant about
this functionality. I think there should be good motivation for it if
we want to go forward with it.
> int error = 0;
> char buf[PATH_MAX];
> + struct dirfn dirfn;
>
> if (!errfunc) errfunc = ignore_err;
>
> + if (flags & GLOB_ALTDIRFUNC) {
> + dirfn.closedir = g->gl_closedir;
> + dirfn.readdir = g->gl_readdir;
> + dirfn.opendir = g->gl_opendir;
> + dirfn.lstat = g->gl_lstat;
> + dirfn.stat = g->gl_stat;
> + } else {
> + dirfn.closedir = wrap_closedir;
> + dirfn.readdir = wrap_readdir;
> + dirfn.opendir = wrap_opendir;
> + dirfn.lstat = lstat;
> + dirfn.stat = stat;
> + }
> +
> if (!(flags & GLOB_APPEND)) {
> g->gl_offs = offs;
> g->gl_pathc = 0;
> @@ -249,7 +276,7 @@ int glob(const char *restrict pat, int flags, int (*errfunc)(const char *path, i
> if ((flags & (GLOB_TILDE | GLOB_TILDE_CHECK)) && *p == '~')
> error = expand_tilde(&s, buf, &pos);
> if (!error)
> - error = do_glob(buf, pos, 0, s, flags, errfunc, &tail);
> + error = do_glob(buf, pos, 0, s, flags, errfunc, &dirfn, &tail);
> free(p);
> }
Not necessary for correctness, but if we're adding a context structure
that gets passed down to each level of do_glob, we might as well put
the errfunc in it too, and possibly also flags and &tail in it, so
that we reduce the amount of state at each recursion frame rather than
increasing it.
It's likely this would make more sense to do as a separate patch
though, to keep the diffs clear.
Rich
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-09-06 21:42 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2019-09-06 19:40 [PATCH v4 1/2] add internal aliases __opendir, __readdir and __closedir Ismael Luceno
2019-09-06 19:40 ` [PATCH v4 2/2] glob: implement GLOB_ALTDIRFUNC et al Ismael Luceno
2019-09-06 21:42 ` Rich Felker
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