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LD_PRELOAD: add dup2 support so we can use it with dd

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This commit is contained in:
Ronnie Sahlberg
2011-02-13 07:36:26 +11:00
parent 0c6025b01b
commit 52b7ae3152
2 changed files with 148 additions and 68 deletions
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2
README
View File

@@ -94,6 +94,8 @@ Change: 1970-01-01 10:00:00.000000000 +1000
The cat command, which allows you to read/dump a iSCSI LUN to a file :
$ LD_PRELOAD=./bin/ld_iscsi.so cat iscsi://127.0.0.1:3262/iqn.ronnie.test/2 >copy_of_iscsi_lun
Or using dd even :
LD_PRELOAD=./bin/ld_iscsi.so strace -o x -f dd if=iscsi://127.0.0.1:3262/iqn.ronnie.test/2 of=copy_of_LUN bs=10M count=1 bs=1M count=10
The LD_PRELOAD hack is incomplete and needs more functions to be intercepted before becomming fully functional. Patches welcome!

214
src/ld_iscsi.c
View File

@@ -9,17 +9,20 @@
#include <stdio.h>
#include "iscsi.h"
#include "iscsi-private.h"
#include "scsi-lowlevel.h"
#include <sys/syscall.h>
#include <dlfcn.h>
#define ISCSI_FD_MASK 0x7fffff00
#define ISCSI_FD_NUM 0x000000ff
static char *initiator = "iqn.2011-02.ronnie:ld_iscsi";
#define ISCSI_MAX_FD 255
struct iscsi_fd_list {
int is_iscsi;
int dup2fd;
int in_flight;
struct iscsi_context *iscsi;
int lun;
uint32_t block_size;
@@ -27,77 +30,62 @@ struct iscsi_fd_list {
off_t offset;
};
static struct iscsi_fd_list iscsi_fd_list[ISCSI_FD_NUM];
static struct iscsi_fd_list iscsi_fd_list[ISCSI_MAX_FD];
int (*real_open)(__const char *path, int flags, mode_t mode);
int open(const char *path, int flags, mode_t mode)
{
int fd;
if (!strncmp(path, "iscsi:", 6)) {
struct iscsi_context *iscsi;
struct iscsi_url *iscsi_url;
struct scsi_task *task;
struct scsi_readcapacity10 *rc10;
int i;
for (i = 0; i < ISCSI_FD_NUM; i++) {
if (iscsi_fd_list[i].iscsi == NULL) {
iscsi_fd_list[i].iscsi = iscsi_create_context(initiator);
break;
}
}
if (i == ISCSI_FD_NUM) {
iscsi = iscsi_create_context(initiator);
if (iscsi == NULL) {
fprintf(stderr, "ld-iscsi: Failed to create context\n");
errno = ENFILE;
return -1;
}
if (iscsi_fd_list[i].iscsi == NULL) {
fprintf(stderr, "ld-iscsi: Failed to create context\n");
iscsi_fd_list[i].iscsi = NULL;
errno = ENOMEM;
return -1;
}
iscsi_url = iscsi_parse_full_url(iscsi_fd_list[i].iscsi, path);
iscsi_url = iscsi_parse_full_url(iscsi, path);
if (iscsi_url == NULL) {
fprintf(stderr, "ld-iscsi: Failed to parse URL: %s\n",
iscsi_get_error(iscsi_fd_list[i].iscsi));
iscsi_destroy_context(iscsi_fd_list[i].iscsi);
iscsi_fd_list[i].iscsi = NULL;
iscsi_get_error(iscsi));
iscsi_destroy_context(iscsi);
errno = EINVAL;
return -1;
}
iscsi_set_targetname(iscsi_fd_list[i].iscsi, iscsi_url->target);
iscsi_set_session_type(iscsi_fd_list[i].iscsi, ISCSI_SESSION_NORMAL);
iscsi_set_header_digest(iscsi_fd_list[i].iscsi, ISCSI_HEADER_DIGEST_NONE_CRC32C);
iscsi_set_targetname(iscsi, iscsi_url->target);
iscsi_set_session_type(iscsi, ISCSI_SESSION_NORMAL);
iscsi_set_header_digest(iscsi, ISCSI_HEADER_DIGEST_NONE_CRC32C);
if (iscsi_url->user != NULL) {
if (iscsi_set_initiator_username_pwd(iscsi_fd_list[i].iscsi, iscsi_url->user, iscsi_url->passwd) != 0) {
if (iscsi_set_initiator_username_pwd(iscsi, iscsi_url->user, iscsi_url->passwd) != 0) {
fprintf(stderr, "Failed to set initiator username and password\n");
iscsi_destroy_context(iscsi_fd_list[i].iscsi);
iscsi_fd_list[i].iscsi = NULL;
iscsi_destroy_context(iscsi);
errno = ENOMEM;
return -1;
}
}
if (iscsi_full_connect_sync(iscsi_fd_list[i].iscsi, iscsi_url->portal, iscsi_url->lun) != 0) {
fprintf(stderr, "ld-iscsi: Login Failed. %s\n", iscsi_get_error(iscsi_fd_list[i].iscsi));
if (iscsi_full_connect_sync(iscsi, iscsi_url->portal, iscsi_url->lun) != 0) {
fprintf(stderr, "ld-iscsi: Login Failed. %s\n", iscsi_get_error(iscsi));
iscsi_destroy_url(iscsi_url);
iscsi_destroy_context(iscsi_fd_list[i].iscsi);
iscsi_fd_list[i].iscsi = NULL;
iscsi_destroy_context(iscsi);
errno = EIO;
return -1;
}
task = iscsi_readcapacity10_sync(iscsi_fd_list[i].iscsi, iscsi_url->lun, 0, 0);
task = iscsi_readcapacity10_sync(iscsi, iscsi_url->lun, 0, 0);
if (task == NULL || task->status != SCSI_STATUS_GOOD) {
fprintf(stderr, "ld-iscsi: failed to send readcapacity command\n");
iscsi_destroy_url(iscsi_url);
iscsi_destroy_context(iscsi_fd_list[i].iscsi);
iscsi_fd_list[i].iscsi = NULL;
iscsi_destroy_context(iscsi);
errno = EIO;
return -1;
}
@@ -107,61 +95,109 @@ int open(const char *path, int flags, mode_t mode)
fprintf(stderr, "ld-iscsi: failed to unmarshall readcapacity10 data\n");
scsi_free_scsi_task(task);
iscsi_destroy_url(iscsi_url);
iscsi_destroy_context(iscsi_fd_list[i].iscsi);
iscsi_fd_list[i].iscsi = NULL;
iscsi_destroy_context(iscsi);
errno = EIO;
return -1;
}
iscsi_fd_list[i].block_size = rc10->block_size;
iscsi_fd_list[i].num_blocks = rc10->lba;
iscsi_fd_list[i].offset = 0;
iscsi_fd_list[i].lun = iscsi_url->lun;
fd = iscsi_get_fd(iscsi);
if (fd >= ISCSI_MAX_FD) {
fprintf(stderr, "ld-iscsi: Too many files open\n");
iscsi_destroy_url(iscsi_url);
iscsi_destroy_context(iscsi);
errno = ENFILE;
return -1;
}
iscsi_fd_list[fd].is_iscsi = 1;
iscsi_fd_list[fd].dup2fd = -1;
iscsi_fd_list[fd].iscsi = iscsi;
iscsi_fd_list[fd].block_size = rc10->block_size;
iscsi_fd_list[fd].num_blocks = rc10->lba;
iscsi_fd_list[fd].offset = 0;
iscsi_fd_list[fd].lun = iscsi_url->lun;
scsi_free_scsi_task(task);
iscsi_destroy_url(iscsi_url);
return ISCSI_FD_MASK | i;
return fd;
}
return(real_open(path, flags, mode));
return real_open(path, flags, mode);
}
int (*real_close)(int fd);
int close(int fd)
{
if ((fd & ISCSI_FD_MASK) == ISCSI_FD_MASK) {
if (iscsi_fd_list[fd].is_iscsi == 1) {
int i;
i = fd & ISCSI_FD_NUM;
if (iscsi_fd_list[fd].dup2fd >= 0) {
iscsi_fd_list[fd].is_iscsi = 0;
iscsi_fd_list[fd].dup2fd = -1;
real_close(fd);
return 0;
}
iscsi_destroy_context(iscsi_fd_list[i].iscsi);
iscsi_fd_list[i].iscsi = NULL;
/* are there any FDs dup2ed onto this ? */
for(i = 0; i < ISCSI_MAX_FD; i++) {
if (iscsi_fd_list[i].dup2fd == fd) {
break;
}
}
if (i < ISCSI_MAX_FD) {
int j;
/* yes there are DUPs onto fd, make i the new real device and repoint all other
* duplicates
*/
memcpy(&iscsi_fd_list[i], &iscsi_fd_list[fd], sizeof(struct iscsi_fd_list));
iscsi_fd_list[i].dup2fd = -1;
memset(&iscsi_fd_list[fd], 0, sizeof(struct iscsi_fd_list));
iscsi_fd_list[fd].dup2fd = -1;
iscsi_fd_list[i].iscsi->fd = i;
real_close(fd);
for(j = 0; j < ISCSI_MAX_FD; j++) {
if (j != i && iscsi_fd_list[j].dup2fd == fd) {
iscsi_fd_list[j].dup2fd = i;
}
}
return 0;
}
iscsi_fd_list[fd].is_iscsi = 0;
iscsi_fd_list[fd].dup2fd = -1;
iscsi_destroy_context(iscsi_fd_list[fd].iscsi);
iscsi_fd_list[fd].iscsi = NULL;
return 0;
}
return(real_close(fd));
return real_close(fd);
}
int (*real_fxstat)(int ver, int fd, struct stat *buf);
int __fxstat(int ver, int fd, struct stat *buf)
{
if ((fd & ISCSI_FD_MASK) == ISCSI_FD_MASK) {
int i;
i = fd & ISCSI_FD_NUM;
if (iscsi_fd_list[fd].is_iscsi == 1) {
if (iscsi_fd_list[fd].dup2fd >= 0) {
return __fxstat(ver, iscsi_fd_list[fd].dup2fd, buf);
}
memset(buf, 0, sizeof(struct stat));
buf->st_mode = S_IRUSR | S_IRGRP | S_IROTH | S_IFREG;
buf->st_size = iscsi_fd_list[i].num_blocks * iscsi_fd_list[i].block_size;
buf->st_size = iscsi_fd_list[fd].num_blocks * iscsi_fd_list[fd].block_size;
return 0;
}
return(real_fxstat(ver, fd, buf));
return real_fxstat(ver, fd, buf);
}
@@ -182,7 +218,7 @@ int __lxstat(int ver, const char *path, struct stat *buf)
return ret;
}
return(real_lxstat(ver, path, buf));
return real_lxstat(ver, path, buf);
}
int (*real_xstat)(int ver, __const char *path, struct stat *buf);
@@ -196,37 +232,73 @@ ssize_t (*real_read)(int fd, void *buf, size_t count);
ssize_t read(int fd, void *buf, size_t count)
{
if ((fd & ISCSI_FD_MASK) == ISCSI_FD_MASK) {
int i;
if ((iscsi_fd_list[fd].is_iscsi == 1) && (iscsi_fd_list[fd].in_flight == 0)) {
uint64_t offset;
uint32_t num_blocks;
struct scsi_task *task;
i = fd & ISCSI_FD_NUM;
if (iscsi_fd_list[fd].dup2fd >= 0) {
return read(iscsi_fd_list[fd].dup2fd, buf, count);
}
offset = iscsi_fd_list[fd].offset / iscsi_fd_list[fd].block_size * iscsi_fd_list[fd].block_size;
num_blocks = (iscsi_fd_list[fd].offset - offset + count + iscsi_fd_list[fd].block_size - 1) / iscsi_fd_list[fd].block_size;
offset = iscsi_fd_list[i].offset / iscsi_fd_list[i].block_size * iscsi_fd_list[i].block_size;
num_blocks = (iscsi_fd_list[i].offset - offset + count + iscsi_fd_list[i].block_size - 1) / iscsi_fd_list[i].block_size;
task = iscsi_read10_sync(iscsi_fd_list[i].iscsi, iscsi_fd_list[i].lun, offset / iscsi_fd_list[i].block_size, num_blocks * iscsi_fd_list[i].block_size, iscsi_fd_list[i].block_size);
iscsi_fd_list[fd].in_flight = 1;
task = iscsi_read10_sync(iscsi_fd_list[fd].iscsi, iscsi_fd_list[fd].lun, offset / iscsi_fd_list[fd].block_size, num_blocks * iscsi_fd_list[fd].block_size, iscsi_fd_list[fd].block_size);
iscsi_fd_list[fd].in_flight = 0;
if (task == NULL || task->status != SCSI_STATUS_GOOD) {
fprintf(stderr, "ld-iscsi: failed to send read10 command\n");
errno = EIO;
return -1;
}
memcpy(buf, &task->datain.data[iscsi_fd_list[i].offset - offset], count);
iscsi_fd_list[i].offset += count;
memcpy(buf, &task->datain.data[iscsi_fd_list[fd].offset - offset], count);
iscsi_fd_list[fd].offset += count;
scsi_free_scsi_task(task);
return count;
}
return(real_read(fd, buf, count));
return real_read(fd, buf, count);
}
int (*real_dup2)(int oldfd, int newfd);
int dup2(int oldfd, int newfd)
{
close(newfd);
if (iscsi_fd_list[oldfd].is_iscsi == 1) {
int ret;
if (iscsi_fd_list[oldfd].dup2fd >= 0) {
return dup2(iscsi_fd_list[oldfd].dup2fd, newfd);
}
ret = real_dup2(oldfd, newfd);
if (ret < 0) {
return ret;
}
iscsi_fd_list[newfd].is_iscsi = 1;
iscsi_fd_list[newfd].dup2fd = oldfd;
return newfd;
}
return real_dup2(oldfd, newfd);
}
void _init(void)
{
int i;
for(i = 0; i < ISCSI_MAX_FD; i++) {
iscsi_fd_list[i].dup2fd = -1;
}
real_open = dlsym(RTLD_NEXT, "open");
if (real_open == NULL) {
fprintf(stderr, "ld_iscsi: Failed to dlsym(open)\n");
@@ -261,4 +333,10 @@ void _init(void)
fprintf(stderr, "ld_iscsi: Failed to dlsym(read)\n");
exit(10);
}
real_dup2 = dlsym(RTLD_NEXT, "dup2");
if (real_dup2 == NULL) {
fprintf(stderr, "ld_iscsi: Failed to dlsym(dup2)\n");
exit(10);
}
}