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459 lines
10 KiB
459 lines
10 KiB
/*
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* readdir accelerator
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*
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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 -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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* %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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* %End-Header%
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*
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*/
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#define ALLOC_STEPSIZE 100
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#define MAX_DIRSIZE 0
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#define DEBUG
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/* Util we autoconfiscate spd_readdir... */
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#define HAVE___SECURE_GETENV 1
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#define HAVE_PRCTL 1
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#define HAVE_SYS_PRCTL_H 1
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#ifdef DEBUG
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#define DEBUG_DIR(x) {if (do_debug) { x; }}
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#else
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#define DEBUG_DIR(x)
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#endif
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#define _GNU_SOURCE
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#define __USE_LARGEFILE64
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <stdlib.h>
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#include <string.h>
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#include <dirent.h>
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#include <errno.h>
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#include <dlfcn.h>
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#ifdef HAVE_SYS_PRCTL_H
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#include <sys/prctl.h>
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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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long long d_off;
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unsigned short int d_reclen;
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unsigned char d_type;
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char *d_name;
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};
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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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int pos;
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int direct;
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struct dirent ret_dir;
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struct dirent64 ret_dir64;
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};
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static int (*real_closedir)(DIR *dir) = 0;
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static DIR *(*real_opendir)(const char *name) = 0;
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static DIR *(*real_fdopendir)(int fd) = 0;
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static void *(*real_rewinddir)(DIR *dirp) = 0;
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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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static unsigned long max_dirsize = MAX_DIRSIZE;
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static int num_open = 0;
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#ifdef DEBUG
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static int do_debug = 0;
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#endif
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static char *safe_getenv(const char *arg)
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{
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if ((getuid() != geteuid()) || (getgid() != getegid()))
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return NULL;
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#if HAVE_PRCTL
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if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
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return NULL;
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#else
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#if (defined(linux) && defined(SYS_prctl))
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if (syscall(SYS_prctl, PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
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return NULL;
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#endif
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#endif
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#if HAVE___SECURE_GETENV
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return __secure_getenv(arg);
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#else
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return getenv(arg);
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#endif
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}
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static void setup_ptr()
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{
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char *cp;
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real_opendir = dlsym(RTLD_NEXT, "opendir");
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real_fdopendir = dlsym(RTLD_NEXT, "fdopendir");
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real_closedir = dlsym(RTLD_NEXT, "closedir");
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real_rewinddir = dlsym(RTLD_NEXT, "rewinddir");
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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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if ((cp = safe_getenv("SPD_READDIR_MAX_SIZE")) != NULL) {
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max_dirsize = atol(cp);
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}
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#ifdef DEBUG
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if (safe_getenv("SPD_READDIR_DEBUG")) {
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printf("initialized!\n");
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do_debug++;
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}
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#endif
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}
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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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for (i=0; i < dirstruct->num; i++) {
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free(dirstruct->dp[i].d_name);
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}
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free(dirstruct->dp);
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dirstruct->dp = 0;
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dirstruct->max = dirstruct->num = 0;
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}
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static int ino_cmp(const void *a, const void *b)
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{
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const struct dirent_s *ds_a = (const struct dirent_s *) a;
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const struct dirent_s *ds_b = (const struct dirent_s *) b;
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ino_t i_a, i_b;
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i_a = ds_a->d_ino;
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i_b = ds_b->d_ino;
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if (ds_a->d_name[0] == '.') {
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if (ds_a->d_name[1] == 0)
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i_a = 0;
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else if ((ds_a->d_name[1] == '.') && (ds_a->d_name[2] == 0))
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i_a = 1;
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}
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if (ds_b->d_name[0] == '.') {
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if (ds_b->d_name[1] == 0)
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i_b = 0;
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else if ((ds_b->d_name[1] == '.') && (ds_b->d_name[2] == 0))
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i_b = 1;
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}
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return (i_a - i_b);
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}
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static 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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static void cache_dirstruct(struct dir_s *dirstruct)
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{
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struct dirent_s *ds, *dnew;
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struct dirent64 *d;
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while ((d = (*real_readdir64)(dirstruct->dir)) != NULL) {
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if (dirstruct->num >= dirstruct->max) {
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dirstruct->max += ALLOC_STEPSIZE;
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DEBUG_DIR(printf("Reallocating to size %d\n",
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dirstruct->max));
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dnew = realloc(dirstruct->dp,
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dirstruct->max * sizeof(struct dir_s));
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if (!dnew)
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goto nomem;
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dirstruct->dp = dnew;
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}
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ds = &dirstruct->dp[dirstruct->num++];
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ds->d_ino = d->d_ino;
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ds->d_off = d->d_off;
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ds->d_reclen = d->d_reclen;
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ds->d_type = d->d_type;
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if ((ds->d_name = malloc(strlen(d->d_name)+1)) == NULL) {
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dirstruct->num--;
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goto nomem;
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}
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strcpy(ds->d_name, d->d_name);
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DEBUG_DIR(printf("readdir: %lu %s\n",
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(unsigned long) d->d_ino, d->d_name));
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}
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qsort(dirstruct->dp, dirstruct->num, sizeof(struct dirent_s), ino_cmp);
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return;
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nomem:
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DEBUG_DIR(printf("No memory, backing off to direct readdir\n"));
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free_cached_dir(dirstruct);
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dirstruct->direct = 1;
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}
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DIR *opendir(const char *name)
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{
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DIR *dir;
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struct dir_s *dirstruct;
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struct stat st;
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if (!real_opendir)
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setup_ptr();
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DEBUG_DIR(printf("Opendir(%s) (%d open)\n", name, num_open++));
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dir = (*real_opendir)(name);
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if (!dir)
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return NULL;
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dirstruct = alloc_dirstruct(dir);
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if (!dirstruct) {
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(*real_closedir)(dir);
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errno = -ENOMEM;
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return NULL;
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}
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if (max_dirsize && (stat(name, &st) == 0) &&
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(st.st_size > max_dirsize)) {
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DEBUG_DIR(printf("Directory size %ld, using direct readdir\n",
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st.st_size));
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dirstruct->direct = 1;
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return (DIR *) dirstruct;
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}
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cache_dirstruct(dirstruct);
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return ((DIR *) dirstruct);
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}
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DIR *fdopendir(int fd)
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{
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DIR *dir;
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struct dir_s *dirstruct;
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struct stat st;
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if (!real_fdopendir)
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setup_ptr();
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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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dirstruct = alloc_dirstruct(dir);
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if (!dirstruct) {
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(*real_closedir)(dir);
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errno = -ENOMEM;
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return NULL;
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}
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if (max_dirsize && (fstat(fd, &st) == 0) &&
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(st.st_size > max_dirsize)) {
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DEBUG_DIR(printf("Directory size %ld, using direct readdir\n",
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st.st_size));
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dirstruct->dir = dir;
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dirstruct->direct = 1;
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return (DIR *) dirstruct;
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}
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cache_dirstruct(dirstruct);
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return ((DIR *) dirstruct);
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}
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int closedir(DIR *dir)
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{
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struct dir_s *dirstruct = (struct dir_s *) dir;
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DEBUG_DIR(printf("Closedir (%d open)\n", --num_open));
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if (dirstruct->dir)
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(*real_closedir)(dirstruct->dir);
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free_cached_dir(dirstruct);
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free(dirstruct);
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return 0;
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}
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struct dirent *readdir(DIR *dir)
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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_readdir)(dirstruct->dir);
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if (dirstruct->pos >= dirstruct->num)
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return NULL;
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ds = &dirstruct->dp[dirstruct->pos++];
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dirstruct->ret_dir.d_ino = ds->d_ino;
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dirstruct->ret_dir.d_off = ds->d_off;
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dirstruct->ret_dir.d_reclen = ds->d_reclen;
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dirstruct->ret_dir.d_type = ds->d_type;
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strncpy(dirstruct->ret_dir.d_name, ds->d_name,
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sizeof(dirstruct->ret_dir.d_name));
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return (&dirstruct->ret_dir);
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}
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int readdir_r(DIR *dir, struct dirent *entry, struct dirent **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_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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} 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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pthread_mutex_unlock(&(dirstruct->lock));
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return 0;
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}
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struct dirent64 *readdir64(DIR *dir)
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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)(dirstruct->dir);
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if (dirstruct->pos >= dirstruct->num)
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return NULL;
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ds = &dirstruct->dp[dirstruct->pos++];
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dirstruct->ret_dir64.d_ino = ds->d_ino;
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dirstruct->ret_dir64.d_off = ds->d_off;
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dirstruct->ret_dir64.d_reclen = ds->d_reclen;
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dirstruct->ret_dir64.d_type = ds->d_type;
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strncpy(dirstruct->ret_dir64.d_name, ds->d_name,
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sizeof(dirstruct->ret_dir64.d_name));
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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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if (dirstruct->direct)
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return (*real_telldir)(dirstruct->dir);
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return ((off_t) dirstruct->pos);
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}
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void seekdir(DIR *dir, off_t offset)
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{
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struct dir_s *dirstruct = (struct dir_s *) dir;
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if (dirstruct->direct) {
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(*real_seekdir)(dirstruct->dir, offset);
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return;
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}
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dirstruct->pos = offset;
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}
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void rewinddir(DIR *dir)
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{
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struct dir_s *dirstruct = (struct dir_s *) dir;
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(*real_rewinddir)(dirstruct->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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{
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struct dir_s *dirstruct = (struct dir_s *) dir;
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int fd = (*real_dirfd)(dirstruct->dir);
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DEBUG_DIR(printf("dirfd %d, %p\n", fd, real_dirfd));
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return fd;
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}
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