From: Ronnie Sahlberg Date: Mon, 3 Feb 2014 02:03:50 +0000 (-0800) Subject: Add a simple LD_PRELOAD toy to make cat and cp nfs-aware X-Git-Tag: upstream/1.9.6^2~117 X-Git-Url: https://git.piment-noir.org/?a=commitdiff_plain;h=b8c28d541ed467139a5c1ca5b60a9ff0da6331de;p=deb_libnfs.git Add a simple LD_PRELOAD toy to make cat and cp nfs-aware --- diff --git a/README b/README index f717c07..4e312da 100644 --- a/README +++ b/README @@ -86,6 +86,25 @@ Android: AROS: - Build with 'make -f aros/Makefile.AROS' +LD_PRELOAD +========== +examples/ld_nfs.c contains a LD_PRELOADable module that can be used to make +several standard utilities nfs aware. +It is still very incomplete but can be used for basic things such as cat and cp. +Patches to add more coverage is welcome. + +Compile with : +gcc -fPIC -shared -o ld_nfs.so examples/ld_nfs.c -ldl -lnfs + +Then try things like +LD_NFS_DEBUG=9 LD_PRELOAD=./ld_nfs.so cat nfs://127.0.0.1/data/tmp/foo123 + +LD_NFS_DEBUG=9 LD_PRELOAD=./ld_nfs.so cp nfs://127.0.0.1/data/tmp/foo123 nfs://127.0.0.1/data/tmp/foo123.copy + +This is just a toy preload module. Don't open bugs if it does not work. Send +patches to make it better instead. + + RELEASE TARBALLS ================ Release tarballs are available at https://sites.google.com/site/libnfstarballs/li diff --git a/examples/ld_nfs.c b/examples/ld_nfs.c new file mode 100644 index 0000000..0620bd6 --- /dev/null +++ b/examples/ld_nfs.c @@ -0,0 +1,700 @@ +/* + Copyright (C) 2014 by Ronnie Sahlberg + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with this program; if not, see . +*/ + +#define _GNU_SOURCE + +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include +#include + +#define NFS_MAX_FD 255 + +static int debug = 0; + +#ifndef discard_const +#define discard_const(ptr) ((void *)((intptr_t)(ptr))) +#endif + +#define LD_NFS_DPRINTF(level, fmt, args...) \ + do { \ + if ((debug) >= level) { \ + fprintf(stderr,"ld_nfs: "); \ + fprintf(stderr, (fmt), ##args); \ + fprintf(stderr,"\n"); \ + } \ + } while (0); + +struct nfs_fd_list { + int is_nfs; + struct nfs_context *nfs; + struct nfsfh *fh; + + /* so we can reopen and emulate dup2() */ + const char *path; + int flags; + mode_t mode; +}; + +static struct nfs_fd_list nfs_fd_list[NFS_MAX_FD]; + +int (*real_open)(__const char *path, int flags, mode_t mode); + +int open(const char *path, int flags, mode_t mode) +{ + if (!strncmp(path, "nfs:", 4)) { + struct nfs_context *nfs; + struct nfs_url *url; + struct nfsfh *fh = NULL; + int ret, fd; + + LD_NFS_DPRINTF(9, "open(%s, %x, %o)", path, flags, mode); + nfs = nfs_init_context(); + if (nfs == NULL) { + LD_NFS_DPRINTF(1, "Failed to create context"); + errno = ENOMEM; + return -1; + } + + url = nfs_parse_url_full(nfs, path); + if (url == NULL) { + LD_NFS_DPRINTF(1, "Failed to parse URL: %s\n", + nfs_get_error(nfs)); + nfs_destroy_context(nfs); + errno = EINVAL; + return -1; + } + + if (nfs_mount(nfs, url->server, url->path) != 0) { + LD_NFS_DPRINTF(1, "Failed to mount nfs share : %s\n", + nfs_get_error(nfs)); + nfs_destroy_url(url); + nfs_destroy_context(nfs); + errno = EINVAL; + return -1; + } + + if (flags & O_CREAT) { + if ((ret = nfs_creat(nfs, url->file, mode, &fh)) != 0) { + LD_NFS_DPRINTF(1, "Failed to creat nfs file : " + "%s\n", nfs_get_error(nfs)); + nfs_destroy_url(url); + nfs_destroy_context(nfs); + errno = -ret; + return -1; + } + } else { + if ((ret = nfs_open(nfs, url->file, flags, &fh)) != 0) { + LD_NFS_DPRINTF(1, "Failed to open nfs file : " + "%s\n", nfs_get_error(nfs)); + nfs_destroy_url(url); + nfs_destroy_context(nfs); + errno = -ret; + return -1; + } + } + + fd = nfs_get_fd(nfs); + if (fd >= NFS_MAX_FD) { + LD_NFS_DPRINTF(1, "Too many files open"); + nfs_destroy_url(url); + nfs_destroy_context(nfs); + errno = ENFILE; + return -1; + } + + nfs_fd_list[fd].is_nfs = 1; + nfs_fd_list[fd].nfs = nfs; + nfs_fd_list[fd].fh = fh; + nfs_fd_list[fd].path = strdup(path); + nfs_fd_list[fd].flags = flags; + nfs_fd_list[fd].mode = mode; + + nfs_destroy_url(url); + + LD_NFS_DPRINTF(9, "open(%s) == %d", path, fd); + return fd; + } + + return real_open(path, flags, mode); +} + +int open64(const char *path, int flags, mode_t mode) +{ + return open(path, flags | O_LARGEFILE, mode); +} + +int (*real_close)(int fd); + +int close(int fd) +{ + if (nfs_fd_list[fd].is_nfs == 1) { + int i; + + LD_NFS_DPRINTF(9, "close(%d)", fd); + + nfs_fd_list[fd].is_nfs = 0; + + nfs_close(nfs_fd_list[fd].nfs, nfs_fd_list[fd].fh); + nfs_fd_list[fd].fh = NULL; + + nfs_destroy_context(nfs_fd_list[fd].nfs); + nfs_fd_list[fd].nfs = NULL; + + free(discard_const(nfs_fd_list[fd].path)); + nfs_fd_list[fd].path = NULL; + + return 0; + } + + return real_close(fd); +} + +ssize_t (*real_read)(int fd, void *buf, size_t count); + +ssize_t read(int fd, void *buf, size_t count) +{ + if (nfs_fd_list[fd].is_nfs == 1) { + int ret; + + LD_NFS_DPRINTF(9, "read(fd:%d count:%d)", fd, (int)count); + if ((ret = nfs_read(nfs_fd_list[fd].nfs, nfs_fd_list[fd].fh, + count, buf)) < 0) { + errno = -ret; + return -1; + } + return ret; + } + return real_read(fd, buf, count); +} + +ssize_t (*real_pread)(int fd, void *buf, size_t count, off_t offset); +ssize_t pread(int fd, void *buf, size_t count, off_t offset) { + if (nfs_fd_list[fd].is_nfs == 1) { + int ret; + + LD_NFS_DPRINTF(9, "pread(fd:%d offset:%d count:%d)", fd, + (int)offset, (int)count); + if ((ret = nfs_pread(nfs_fd_list[fd].nfs, nfs_fd_list[fd].fh, + offset, count, buf)) < 0) { + errno = -ret; + return -1; + } + return ret; + } + return real_pread(fd, buf, count, offset); +} + +ssize_t (*real_write)(int fd, const void *buf, size_t count); + +ssize_t write(int fd, const void *buf, size_t count) +{ + if (nfs_fd_list[fd].is_nfs == 1) { + int ret; + + LD_NFS_DPRINTF(9, "write(fd:%d count:%d)", fd, (int)count); + if ((ret = nfs_write(nfs_fd_list[fd].nfs, nfs_fd_list[fd].fh, + count, + (char *)discard_const(buf))) < 0) { + errno = -ret; + return -1; + } + return ret; + } + return real_write(fd, buf, count); +} + +ssize_t (*real_pwrite)(int fd, const void *buf, size_t count, off_t offset); +ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset) { + if (nfs_fd_list[fd].is_nfs == 1) { + int ret; + + LD_NFS_DPRINTF(9, "pwrite(fd:%d offset:%d count:%d)", fd, + (int)offset, (int)count); + if ((ret = nfs_pwrite(nfs_fd_list[fd].nfs, nfs_fd_list[fd].fh, + offset, count, + (char *)discard_const(buf))) < 0) { + errno = -ret; + return -1; + } + return ret; + } + return real_pwrite(fd, buf, count, offset); +} + +int (*real_dup2)(int oldfd, int newfd); + +int dup2(int oldfd, int newfd) +{ + close(newfd); + + if (nfs_fd_list[oldfd].is_nfs == 1) { + struct nfs_context *nfs; + struct nfs_url *url; + struct nfsfh *fh = NULL; + int ret, fd; + + LD_NFS_DPRINTF(9, "dup2(%s:%d, %d)", nfs_fd_list[oldfd].path, + oldfd, newfd); + nfs = nfs_init_context(); + if (nfs == NULL) { + LD_NFS_DPRINTF(1, "Failed to create context"); + errno = ENOMEM; + return -1; + } + + url = nfs_parse_url_full(nfs, nfs_fd_list[oldfd].path); + if (url == NULL) { + LD_NFS_DPRINTF(1, "Failed to parse URL: %s\n", + nfs_get_error(nfs)); + nfs_destroy_context(nfs); + errno = EINVAL; + return -1; + } + + if (nfs_mount(nfs, url->server, url->path) != 0) { + LD_NFS_DPRINTF(1, "Failed to mount nfs share : %s\n", + nfs_get_error(nfs)); + nfs_destroy_url(url); + nfs_destroy_context(nfs); + errno = EINVAL; + return -1; + } + + if ((ret = nfs_open(nfs, url->file, nfs_fd_list[oldfd].mode, + &fh)) != 0) { + LD_NFS_DPRINTF(1, "Failed to open nfs file : %s\n", + nfs_get_error(nfs)); + nfs_destroy_url(url); + nfs_destroy_context(nfs); + errno = -ret; + return -1; + } + + /* We could actually end on the right descriptor by chance */ + if (nfs_get_fd(nfs) != newfd) { + if (real_dup2(nfs_get_fd(nfs), newfd) < 0) { + LD_NFS_DPRINTF(1, "Failed to dup2 file : %d", + errno); + return -1; + } + + close(rpc_get_fd(nfs_get_rpc_context(nfs))); + rpc_set_fd(nfs_get_rpc_context(nfs), newfd); + } + + fd = nfs_get_fd(nfs); + if (fd >= NFS_MAX_FD) { + LD_NFS_DPRINTF(1, "Too many files open"); + nfs_destroy_url(url); + nfs_destroy_context(nfs); + errno = ENFILE; + return -1; + } + + nfs_fd_list[fd].is_nfs = 1; + nfs_fd_list[fd].nfs = nfs; + nfs_fd_list[fd].fh = fh; + nfs_fd_list[fd].path = strdup(nfs_fd_list[oldfd].path); + nfs_fd_list[fd].flags = nfs_fd_list[oldfd].flags; + nfs_fd_list[fd].mode = nfs_fd_list[oldfd].mode; + + nfs_destroy_url(url); + + LD_NFS_DPRINTF(9, "dup2(%s) successful", + nfs_fd_list[oldfd].path); + return fd; + } + + return real_dup2(oldfd, newfd); +} + +int (*real_xstat)(int ver, __const char *path, struct stat *buf); + +int __xstat(int ver, const char *path, struct stat *buf) +{ + if (!strncmp(path, "nfs:", 4)) { + int fd, ret; + + LD_NFS_DPRINTF(9, "__xstat(%s)", path); + fd = open(path, 0, 0); + if (fd == -1) { + return fd; + } + + ret = __fxstat(ver, fd, buf); + close(fd); + return ret; + } + + return real_xstat(ver, path, buf); +} + +int (*real_xstat64)(int ver, __const char *path, struct stat64 *buf); + +int __xstat64(int ver, const char *path, struct stat64 *buf) +{ + if (!strncmp(path, "nfs:", 4)) { + int fd, ret; + + LD_NFS_DPRINTF(9, "__xstat64(%s)", path); + fd = open(path, 0, 0); + if (fd == -1) { + return fd; + } + + ret = __fxstat64(ver, fd, buf); + close(fd); + return ret; + } + + return real_xstat64(ver, path, buf); +} + +int (*real_lxstat)(int ver, __const char *path, struct stat *buf); + +int __lxstat(int ver, const char *path, struct stat *buf) +{ + if (!strncmp(path, "nfs:", 4)) { + int fd, ret; + + LD_NFS_DPRINTF(9, "__lxstat(%s)", path); + fd = open(path, 0, 0); + if (fd == -1) { + return fd; + } + + ret = __fxstat(ver, fd, buf); + close(fd); + return ret; + } + + return real_lxstat(ver, path, buf); +} + +int (*real_lxstat64)(int ver, __const char *path, struct stat64 *buf); + +int __lxstat64(int ver, const char *path, struct stat64 *buf) +{ + if (!strncmp(path, "nfs:", 4)) { + int fd, ret; + + LD_NFS_DPRINTF(9, "__lxstat64(%s)", path); + fd = open(path, 0, 0); + if (fd == -1) { + return fd; + } + + ret = __fxstat64(ver, fd, buf); + close(fd); + return ret; + } + + return real_lxstat64(ver, path, buf); +} + +int (*real_fxstat)(int ver, int fd, struct stat *buf); + +int __fxstat(int ver, int fd, struct stat *buf) +{ + if (nfs_fd_list[fd].is_nfs == 1) { + int ret; + struct stat64 st64; + + LD_NFS_DPRINTF(9, "__fxstat(%d)", fd); + if ((ret = nfs_fstat(nfs_fd_list[fd].nfs, nfs_fd_list[fd].fh, + (void *)&st64)) < 0) { + errno = -ret; + return -1; + } + + buf->st_dev = st64.st_dev; + buf->st_ino = st64.st_ino; + buf->st_mode = st64.st_mode; + buf->st_nlink = st64.st_nlink; + buf->st_uid = st64.st_uid; + buf->st_gid = st64.st_gid; + buf->st_rdev = st64.st_rdev; + buf->st_size = st64.st_size; + buf->st_blksize = st64.st_blksize; + buf->st_blocks = st64.st_blocks; + buf->st_atime = st64.st_atime; + buf->st_mtime = st64.st_mtime; + buf->st_ctime = st64.st_ctime; + + LD_NFS_DPRINTF(9, "__fxstat(%d) success", fd); + return ret; + } + + return real_fxstat(ver, fd, buf); +} + +int (*real_fxstat64)(int ver, int fd, struct stat64 *buf); + +int __fxstat64(int ver, int fd, struct stat64 *buf) +{ + if (nfs_fd_list[fd].is_nfs == 1) { + int ret; + struct stat64 st64; + + LD_NFS_DPRINTF(9, "__fxstat64(%d)", fd); + if ((ret = nfs_fstat(nfs_fd_list[fd].nfs, nfs_fd_list[fd].fh, + (void *)&st64)) < 0) { + errno = -ret; + return -1; + } + + buf->st_dev = st64.st_dev; + buf->st_ino = st64.st_ino; + buf->st_mode = st64.st_mode; + buf->st_nlink = st64.st_nlink; + buf->st_uid = st64.st_uid; + buf->st_gid = st64.st_gid; + buf->st_rdev = st64.st_rdev; + buf->st_size = st64.st_size; + buf->st_blksize = st64.st_blksize; + buf->st_blocks = st64.st_blocks; + buf->st_atime = st64.st_atime; + buf->st_mtime = st64.st_mtime; + buf->st_ctime = st64.st_ctime; + + LD_NFS_DPRINTF(9, "__fxstat64(%d) success", fd); + return ret; + } + + return real_fxstat64(ver, fd, buf); +} + +int (*real_fallocate)(int fd, int mode, off_t offset, off_t len); + +int fallocate(int fd, int mode, off_t offset, off_t len) +{ + if (nfs_fd_list[fd].is_nfs == 1) { + LD_NFS_DPRINTF(9, "fallocate(%d)", fd); + errno = EOPNOTSUPP; + return -1; + } + + return real_fallocate(fd, mode, offset, len); +} + +int (*real_ftruncate)(int fd, off_t len); + +int ftruncate(int fd, off_t len) +{ + if (nfs_fd_list[fd].is_nfs == 1) { + int ret; + + LD_NFS_DPRINTF(9, "ftruncate(%d, %d)", fd, (int)len); + if ((ret = nfs_ftruncate(nfs_fd_list[fd].nfs, + nfs_fd_list[fd].fh, + len)) < 0) { + errno = -ret; + return -1; + } + return 0; + } + + return real_ftruncate(fd, len); +} + +int (*real_truncate)(const char *path, off_t len); + +int truncate(const char *path, off_t len) +{ + if (!strncmp(path, "nfs:", 4)) { + int fd, ret; + + LD_NFS_DPRINTF(9, "truncate(%s, %d)", path, (int)len); + fd = open(path, 0, 0); + if (fd == -1) { + return fd; + } + + ret = ftruncate(fd, len); + close(fd); + return ret; + } + + return real_truncate(path, len); +} + +int (*real_fchmod)(int fd, mode_t mode); + +int fchmod(int fd, mode_t mode) +{ + if (nfs_fd_list[fd].is_nfs == 1) { + int ret; + + LD_NFS_DPRINTF(9, "fchmod(%d, %o)", fd, (int)mode); + if ((ret = nfs_fchmod(nfs_fd_list[fd].nfs, + nfs_fd_list[fd].fh, + mode)) < 0) { + errno = -ret; + return -1; + } + return 0; + } + + return real_fchmod(fd, mode); +} + +int (*real_chmod)(const char *path, mode_t mode); + +int chmod(const char *path, mode_t mode) +{ + if (!strncmp(path, "nfs:", 4)) { + int fd, ret; + + LD_NFS_DPRINTF(9, "chmod(%s, %o)", path, (int)mode); + fd = open(path, 0, 0); + if (fd == -1) { + return fd; + } + + ret = fchmod(fd, mode); + close(fd); + return ret; + } + + return real_chmod(path, mode); +} + +static void __attribute__((constructor)) _init(void) +{ + int i; + + if (getenv("LD_NFS_DEBUG") != NULL) { + debug = atoi(getenv("LD_NFS_DEBUG")); + } + + real_open = dlsym(RTLD_NEXT, "open"); + if (real_open == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(open)"); + exit(10); + } + + real_close = dlsym(RTLD_NEXT, "close"); + if (real_close == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(close)"); + exit(10); + } + + real_read = dlsym(RTLD_NEXT, "read"); + if (real_read == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(read)"); + exit(10); + } + + real_pread = dlsym(RTLD_NEXT, "pread"); + if (real_pread == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(pread)"); + exit(10); + } + + real_write = dlsym(RTLD_NEXT, "write"); + if (real_write == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(write)"); + exit(10); + } + + real_pwrite = dlsym(RTLD_NEXT, "pwrite"); + if (real_pwrite == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(pwrite)"); + exit(10); + } + + real_xstat = dlsym(RTLD_NEXT, "__xstat"); + if (real_xstat == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(__xstat)"); + exit(10); + } + + real_xstat64 = dlsym(RTLD_NEXT, "__xstat64"); + if (real_xstat64 == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(__xstat64)"); + } + + real_lxstat = dlsym(RTLD_NEXT, "__lxstat"); + if (real_lxstat == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(__lxstat)"); + exit(10); + } + + real_lxstat64 = dlsym(RTLD_NEXT, "__lxstat64"); + if (real_lxstat64 == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(_lxstat64)"); + exit(10); + } + + real_fxstat = dlsym(RTLD_NEXT, "__fxstat"); + if (real_fxstat == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(__fxstat)"); + exit(10); + } + + real_fxstat64 = dlsym(RTLD_NEXT, "__fxstat64"); + if (real_fxstat64 == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(__fxstat64)"); + exit(10); + } + + real_fallocate = dlsym(RTLD_NEXT, "fallocate"); + if (real_fallocate == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(fallocate)"); + exit(10); + } + + real_dup2 = dlsym(RTLD_NEXT, "dup2"); + if (real_dup2 == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(dup2)"); + exit(10); + } + + real_truncate = dlsym(RTLD_NEXT, "truncate"); + if (real_truncate == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(truncate)"); + exit(10); + } + + real_ftruncate = dlsym(RTLD_NEXT, "ftruncate"); + if (real_ftruncate == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(ftruncate)"); + exit(10); + } + + real_chmod = dlsym(RTLD_NEXT, "chmod"); + if (real_chmod == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(chmod)"); + exit(10); + } + + real_fchmod = dlsym(RTLD_NEXT, "fchmod"); + if (real_fchmod == NULL) { + LD_NFS_DPRINTF(0, "Failed to dlsym(fchmod)"); + exit(10); + } +}