mirror of https://github.com/vitalif/e2fsprogs
contrib: add thread locking and readdir64_r support to spd_readdir
This is part of a series of improvements from a 2008 version of spd_readdir.c that somehow didn't make it into the version which we checked into e2fsprogs git tree. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>debian-1.42.9
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0b64f50f71
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@ -1,21 +1,22 @@
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/*
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* readdir accelerator
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*
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* (C) Copyright 2003, 2004 by Theodore Ts'o.
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* (C) Copyright 2003, 2004, 2008 by Theodore Ts'o.
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*
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* 2008-06-08 Modified by Ross Boylan <RossBoylan stanfordalumni org>
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* Added support for readdir_r and readdir64_r calls. Note
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* this has not been tested on anything other than GNU/Linux i386,
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* and that the regular readdir wrapper will take slightly more
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* space than Ted's original since it now includes a lock.
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*
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* Compile using the command:
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*
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* gcc -o spd_readdir.so -fPIC -shared spd_readdir.c -ldl
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* gcc -o spd_readdir.so -shared -fpic spd_readdir.c -ldl
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*
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* Use it by setting the LD_PRELOAD environment variable:
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*
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* export LD_PRELOAD=/usr/local/sbin/spd_readdir.so
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*
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* Note that this preload is not going to work for all programs. In
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* particular, although it does supply readdir_r(), it is *not* thread
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* safe. So I can't recommend this as something to be dropped in
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* /etc/ld.so.preload.
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Public
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* License.
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@ -55,6 +56,7 @@
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#else
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#define PR_GET_DUMPABLE 3
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#endif
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#include <pthread.h>
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struct dirent_s {
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unsigned long long d_ino;
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@ -66,6 +68,7 @@ struct dirent_s {
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struct dir_s {
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DIR *dir;
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pthread_mutex_t lock; /* Mutex lock for this structure. */
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int num;
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int max;
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struct dirent_s *dp;
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@ -83,6 +86,8 @@ static struct dirent *(*real_readdir)(DIR *dir) = 0;
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static int (*real_readdir_r)(DIR *dir, struct dirent *entry,
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struct dirent **result) = 0;
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static struct dirent64 *(*real_readdir64)(DIR *dir) = 0;
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static int (*real_readdir64_r)(DIR *dir, struct dirent64 *entry,
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struct dirent64 **result) = 0;
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static off_t (*real_telldir)(DIR *dir) = 0;
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static void (*real_seekdir)(DIR *dir, off_t offset) = 0;
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static int (*real_dirfd)(DIR *dir) = 0;
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@ -124,6 +129,7 @@ static void setup_ptr()
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real_readdir = dlsym(RTLD_NEXT, "readdir");
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real_readdir_r = dlsym(RTLD_NEXT, "readdir_r");
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real_readdir64 = dlsym(RTLD_NEXT, "readdir64");
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real_readdir64_r = dlsym(RTLD_NEXT, "readdir64_r");
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real_telldir = dlsym(RTLD_NEXT, "telldir");
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real_seekdir = dlsym(RTLD_NEXT, "seekdir");
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real_dirfd = dlsym(RTLD_NEXT, "dirfd");
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@ -142,6 +148,8 @@ static void free_cached_dir(struct dir_s *dirstruct)
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{
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int i;
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pthread_mutex_destroy(&(dirstruct->lock));
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if (!dirstruct->dp)
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return;
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@ -181,11 +189,14 @@ static int ino_cmp(const void *a, const void *b)
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struct dir_s *alloc_dirstruct(DIR *dir)
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{
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struct dir_s *dirstruct;
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static pthread_mutexattr_t mutexattr;
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mutexattr.__align = PTHREAD_MUTEX_RECURSIVE;
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dirstruct = malloc(sizeof(struct dir_s));
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if (dirstruct)
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memset(dirstruct, 0, sizeof(struct dir_s));
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dirstruct->dir = dir;
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pthread_mutex_init(&(dirstruct->lock), &mutexattr);
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return dirstruct;
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}
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@ -268,7 +279,7 @@ DIR *fdopendir(int fd)
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if (!real_fdopendir)
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setup_ptr();
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DEBUG_DIR(printf("fdpendir(%d) (%d open)\n", fd, num_open++));
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DEBUG_DIR(printf("fdopendir(%d) (%d open)\n", fd, num_open++));
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dir = (*real_fdopendir)(fd);
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if (!dir)
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return NULL;
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@ -336,19 +347,19 @@ int readdir_r(DIR *dir, struct dirent *entry, struct dirent **result)
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if (dirstruct->direct)
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return (*real_readdir_r)(dirstruct->dir, entry, result);
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pthread_mutex_lock(&(dirstruct->lock));
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if (dirstruct->pos >= dirstruct->num) {
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*result = NULL;
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return 0;
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} else {
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ds = &dirstruct->dp[dirstruct->pos++];
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entry->d_ino = ds->d_ino;
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entry->d_off = ds->d_off;
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entry->d_reclen = ds->d_reclen;
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entry->d_type = ds->d_type;
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strncpy(entry->d_name, ds->d_name, sizeof(entry->d_name));
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*result = entry;
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}
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ds = &dirstruct->dp[dirstruct->pos++];
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entry->d_ino = ds->d_ino;
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entry->d_off = ds->d_off;
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entry->d_reclen = ds->d_reclen;
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entry->d_type = ds->d_type;
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strncpy(entry->d_name, ds->d_name, sizeof(entry->d_name));
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*result = entry;
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pthread_mutex_unlock(&(dirstruct->lock));
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return 0;
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}
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@ -374,6 +385,32 @@ struct dirent64 *readdir64(DIR *dir)
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return (&dirstruct->ret_dir64);
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}
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int readdir64_r (DIR *__restrict dir,
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struct dirent64 *__restrict entry,
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struct dirent64 **__restrict result)
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{
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struct dir_s *dirstruct = (struct dir_s *) dir;
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struct dirent_s *ds;
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if (dirstruct->direct)
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return (*real_readdir64_r)(dir, entry, result);
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pthread_mutex_lock(&(dirstruct->lock));
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if (dirstruct->pos >= dirstruct->num) {
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*result = NULL;
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} else {
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ds = &dirstruct->dp[dirstruct->pos++];
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entry->d_ino = ds->d_ino;
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entry->d_off = ds->d_off;
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entry->d_reclen = ds->d_reclen;
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entry->d_type = ds->d_type;
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strncpy(entry->d_name, ds->d_name,
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sizeof(entry->d_name));
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*result = entry;
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}
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pthread_mutex_unlock(&(dirstruct->lock));
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return 0;
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}
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off_t telldir(DIR *dir)
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{
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struct dir_s *dirstruct = (struct dir_s *) dir;
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@ -404,9 +441,11 @@ void rewinddir(DIR *dir)
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if (dirstruct->direct)
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return;
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pthread_mutex_lock(&(dirstruct->lock));
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dirstruct->pos = 0;
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free_cached_dir(dirstruct);
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cache_dirstruct(dirstruct);
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pthread_mutex_unlock(&(dirstruct->lock));
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}
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int dirfd(DIR *dir)
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