diff options
Diffstat (limited to 'util/nvmutil/lib/file.c')
| -rw-r--r-- | util/nvmutil/lib/file.c | 890 |
1 files changed, 890 insertions, 0 deletions
diff --git a/util/nvmutil/lib/file.c b/util/nvmutil/lib/file.c new file mode 100644 index 00000000..b4925ccd --- /dev/null +++ b/util/nvmutil/lib/file.c @@ -0,0 +1,890 @@ +/* SPDX-License-Identifier: MIT + * Copyright (c) 2026 Leah Rowe <leah@libreboot.org> + */ + +#include <sys/types.h> +#include <sys/stat.h> + +#include <errno.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include "../include/common.h" + +/* check that a file changed + */ + +int +same_file(int fd, struct stat *st_old, + int check_size) +{ + struct stat st; + int saved_errno = errno; + + if (st_old == NULL || fd < 0) + goto err_same_file; + + if (fstat(fd, &st) == -1) + return -1; + + if (st.st_dev != st_old->st_dev || + st.st_ino != st_old->st_ino || + !S_ISREG(st.st_mode)) + goto err_same_file; + + if (check_size && + st.st_size != st_old->st_size) + goto err_same_file; + + errno = saved_errno; + return 0; + +err_same_file: + + errno = EIO; + return -1; +} + +/* open() but with abort traps + */ + +void +xopen(int *fd_ptr, const char *path, int flags, struct stat *st) +{ + if ((*fd_ptr = open(path, flags)) == -1) + err(errno, "%s", path); + + if (fstat(*fd_ptr, st) == -1) + err(errno, "%s: stat", path); + + if (!S_ISREG(st->st_mode)) + err(errno, "%s: not a regular file", path); + + if (lseek(*fd_ptr, 0, SEEK_CUR) == (off_t)-1) + err(errno, "%s: file not seekable", path); +} + +/* fsync() the directory of a file, + * useful for atomic writes + */ + +int +fsync_dir(const char *path) +{ + int saved_errno = errno; + + unsigned long pathlen; + unsigned long maxlen; + + char *dirbuf; + int dirfd; + + char *slash; + + struct stat st; + +#if defined(PATH_LEN) && \ + (PATH_LEN) >= 256 + maxlen = PATH_LEN; +#else + maxlen = 1024; +#endif + + dirbuf = NULL; + dirfd = -1; + + pathlen = xstrxlen(path, maxlen); + + if (pathlen >= maxlen) { + fprintf(stderr, "Path too long for fsync_parent_dir\n"); + goto err_fsync_dir; + } + + if (pathlen == 0) + { + errno = EINVAL; + goto err_fsync_dir; + } + + dirbuf = malloc(pathlen + 1); + if (dirbuf == NULL) + goto err_fsync_dir; + + memcpy(dirbuf, path, pathlen + 1); + slash = strrchr(dirbuf, '/'); + + if (slash != NULL) { + *slash = '\0'; + if (*dirbuf == '\0') { + dirbuf[0] = '/'; + dirbuf[1] = '\0'; + } + } else { + dirbuf[0] = '.'; + dirbuf[1] = '\0'; + } + + dirfd = open(dirbuf, O_RDONLY +#ifdef O_DIRECTORY + | O_DIRECTORY +#endif +#ifdef O_NOFOLLOW + | O_NOFOLLOW +#endif + ); + if (dirfd == -1) + goto err_fsync_dir; + + if (fstat(dirfd, &st) < 0) + goto err_fsync_dir; + + if (!S_ISDIR(st.st_mode)) { + fprintf(stderr, "%s: not a directory\n", dirbuf); + goto err_fsync_dir; + } + + /* sync file on disk */ + if (fsync_on_eintr(dirfd) == -1) + goto err_fsync_dir; + + if (close_on_eintr(dirfd) == -1) + goto err_fsync_dir; + + if (dirbuf != NULL) + free(dirbuf); + + errno = saved_errno; + return 0; + +err_fsync_dir: + if (!errno) + errno = EIO; + + if (errno != saved_errno) + fprintf(stderr, "%s: %s\n", path, strerror(errno)); + + if (dirbuf != NULL) + free(dirbuf); + + if (dirfd > -1) + close_on_eintr(dirfd); + + errno = saved_errno; + + return -1; +} + +/* returns ptr to path (string). if local>0: + * make tmpfile in the same directory as the + * file. if local==0, use TMPDIR + * + * if local==0, the 3rd argument is ignored + */ + +char * +new_tmpfile(int *fd, int local, const char *path) +{ + unsigned long maxlen; + struct stat st; + + /* please do not modify the + * strings or I will get mad + */ + char tmp_none[] = ""; + char tmp_default[] = "/tmp"; + char default_tmpname[] = "tmpXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"; + char *tmpname; + + char *base = NULL; + char *dest = NULL; + + unsigned long tmpdir_len = 0; + unsigned long tmpname_len = 0; + unsigned long tmppath_len = 0; + + int fd_tmp = -1; + int flags; + +#if defined(PATH_LEN) && \ + (PATH_LEN) >= 256 + maxlen = PATH_LEN; +#else + maxlen = 1024; +#endif + + tmpname = default_tmpname; + if (local) { + if (path == NULL) + goto err_new_tmpfile; + if (*path == '\0') + goto err_new_tmpfile; + + if (stat(path, &st) == -1) + goto err_new_tmpfile; + + if (!S_ISREG(st.st_mode)) + goto err_new_tmpfile; + + tmpname = (char *)path; + } + + if (local) { + base = tmp_none; + + /* appended to filename for tmp: + */ + tmpdir_len = xstrxlen(default_tmpname, maxlen); + } else { + base = get_tmpdir(); + + if (base == NULL) + base = tmp_default; + if (*base == '\0') + base = tmp_default; + + tmpdir_len = xstrxlen(base, maxlen); + } + + tmpname_len = xstrxlen(tmpname, maxlen); + + tmppath_len = tmpdir_len + tmpname_len; + ++tmppath_len; /* for '/' or '.' */ + + /* max length -1 of maxlen + * for termination + */ + if (tmpdir_len > maxlen - tmpname_len - 1) + goto err_new_tmpfile; + + /* +1 for NULL */ + dest = malloc(tmppath_len + 1); + if (dest == NULL) + goto err_new_tmpfile; + + if (local) { + + *dest = '.'; /* hidden file */ + + memcpy(dest + (unsigned long)1, tmpname, tmpname_len); + + memcpy(dest + (unsigned long)1 + tmpname_len, + default_tmpname, tmpdir_len); + } else { + + memcpy(dest, base, tmpdir_len); + + dest[tmpdir_len] = '/'; + + memcpy(dest + tmpdir_len + 1, tmpname, tmpname_len); + } + + dest[tmppath_len] = '\0'; + + fd_tmp = mkstemp_n(dest); + if (fd_tmp == -1) + goto err_new_tmpfile; + + if (fchmod(fd_tmp, 0600) == -1) + goto err_new_tmpfile; + + flags = fcntl(fd_tmp, F_GETFL); + + if (flags == -1) + goto err_new_tmpfile; + + /* + * O_APPEND would permit offsets + * to be ignored, which breaks + * positional read/write + */ + if (flags & O_APPEND) + goto err_new_tmpfile; + + if (lock_file(fd_tmp, flags) == -1) + goto err_new_tmpfile; + + if (fstat(fd_tmp, &st) == -1) + goto err_new_tmpfile; + + /* + * Extremely defensive + * likely pointless checks + */ + + /* check if it's a file */ + if (!S_ISREG(st.st_mode)) + goto err_new_tmpfile; + + /* check if it's seekable */ + if (lseek(fd_tmp, 0, SEEK_CUR) == (off_t)-1) + goto err_new_tmpfile; + + /* tmpfile has >1 hardlinks */ + if (st.st_nlink > 1) + goto err_new_tmpfile; + + /* tmpfile unlinked while opened */ + if (st.st_nlink == 0) + goto err_new_tmpfile; + + *fd = fd_tmp; + + return dest; + +err_new_tmpfile: + + if (dest != NULL) + free(dest); + + if (fd_tmp > -1) + close_on_eintr(fd_tmp); + + return NULL; +} + +int +lock_file(int fd, int flags) +{ + struct flock fl; + + memset(&fl, 0, sizeof(fl)); + + if ((flags & O_ACCMODE) == O_RDONLY) + fl.l_type = F_RDLCK; + else + fl.l_type = F_WRLCK; + + fl.l_whence = SEEK_SET; + + if (fcntl(fd, F_SETLK, &fl) == -1) + return -1; + + return 0; +} + +/* return TMPDIR, or fall back + * to portable defaults + */ + +char * +get_tmpdir(void) +{ + char *t; + struct stat st; + + t = getenv("TMPDIR"); + + if (t && *t) { + + if (stat(t, &st) == 0 && S_ISDIR(st.st_mode)) { + + if ((st.st_mode & S_IWOTH) && !(st.st_mode & S_ISVTX)) + return NULL; + + return t; + } + } + + if (stat("/tmp", &st) == 0 && S_ISDIR(st.st_mode)) + return "/tmp"; + + if (stat("/var/tmp", &st) == 0 && S_ISDIR(st.st_mode)) + return "/var/tmp"; + + return "."; +} + +/* portable mkstemp + */ + +int +mkstemp_n(char *template) +{ + int fd; + unsigned long i, j; + unsigned long len; + char *p; + + unsigned long xc = 0; + + static char ch[] = + "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; + + unsigned long r; +#if defined(PATH_LEN) && \ + (PATH_LEN) >= 256 + unsigned long max_len = PATH_LEN; +#else + unsigned long max_len = 4096; +#endif + + len = xstrxlen(template, max_len); + + if (len < 6) { + errno = EINVAL; + return -1; + } + + p = template + len; + + while (p > template && p[-1] == 'X') { + --p; + ++xc; + } + + if (xc < 6) { + errno = EINVAL; + return -1; + } + + for (i = 0; i < 200; i++) { + + for (j = 0; j < xc; j++) { + + r = rlong(); + + p[j] = ch[(unsigned long)(r >> 1) % (sizeof(ch) - 1)]; + } + + fd = open(template, + O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW | O_CLOEXEC, 0600); + + if (fd >= 0) + return fd; + + if (errno != EEXIST) + return -1; + } + + errno = EEXIST; + return -1; +} + +/* + * Safe I/O functions wrapping around + * read(), write() and providing a portable + * analog of both pread() and pwrite(). + * These functions are designed for maximum + * robustness, checking NULL inputs, overflowed + * outputs, and all kinds of errors that the + * standard libc functions don't. + * + * Looping on EINTR and EAGAIN is supported. + * EINTR/EAGAIN looping is done indefinitely. + */ + +/* rw_file_exact() - Read perfectly or die + * + * Read/write, and absolutely insist on an + * absolute read; e.g. if 100 bytes are + * requested, this MUST return 100. + * + * This function will never return zero. + * It will only return below (error), + * or above (success). On error, -1 is + * returned and errno is set accordingly. + * + * Zero-byte returns are not allowed. + * It will re-spin a finite number of + * times upon zero-return, to recover, + * otherwise it will return an error. + */ + +long +rw_file_exact(int fd, unsigned char *mem, unsigned long nrw, + off_t off, int rw_type, int loop_eagain, + int loop_eintr, unsigned long max_retries, + int off_reset) +{ + long rval; + long rc; + + unsigned long nrw_cur; + + off_t off_cur; + void *mem_cur; + + unsigned long retries_on_zero; + + rval = 0; + + rc = 0; + retries_on_zero = 0; + + if (io_args(fd, mem, nrw, off, rw_type) == -1) + return -1; + + while (1) { + + /* Prevent theoretical overflow */ + if (rval >= 0 && (unsigned long)rval > (nrw - rc)) + goto err_rw_file_exact; + + rc += rval; + if ((unsigned long)rc >= nrw) + break; + + mem_cur = (void *)(mem + (unsigned long)rc); + nrw_cur = (unsigned long)(nrw - (unsigned long)rc); + if (off < 0) + goto err_rw_file_exact; + off_cur = off + (off_t)rc; + + rval = prw(fd, mem_cur, nrw_cur, off_cur, + rw_type, loop_eagain, loop_eintr, + off_reset); + + if (rval < 0) + return -1; + + if (rval == 0) { + if (retries_on_zero++ < max_retries) + continue; + goto err_rw_file_exact; + } + + retries_on_zero = 0; + } + + if ((unsigned long)rc != nrw) + goto err_rw_file_exact; + + return rw_over_nrw(rc, nrw); + +err_rw_file_exact: + errno = EIO; + return -1; +} + +/* prw() - portable read-write with more + * safety checks than barebones libc + * + * portable pwrite/pread on request, or real + * pwrite/pread libc functions can be used. + * the portable (non-libc) pread/pwrite is not + * thread-safe, because it does not prevent or + * mitigate race conditions on file descriptors + * + * If you need real pwrite/pread, just compile + * with flag: HAVE_REAL_PREAD_PWRITE=1 + * + * A fallback is provided for regular read/write. + * rw_type can be IO_READ (read), IO_WRITE (write), + * IO_PREAD (pread) or IO_PWRITE + * + * loop_eagain does a retry loop on EAGAIN if set + * loop_eintr does a retry loop on EINTR if set + * + * race conditions on non-libc pread/pwrite: + * if a file offset changes, abort, to mitage. + * + * off_reset 1: reset the file offset *once* if + * a change was detected, assuming + * nothing else is touching it now + * off_reset 0: never reset if changed + */ + +long +prw(int fd, void *mem, unsigned long nrw, + off_t off, int rw_type, + int loop_eagain, int loop_eintr, + int off_reset) +{ + long r; + int positional_rw; + struct stat st; +#if !defined(HAVE_REAL_PREAD_PWRITE) || \ + HAVE_REAL_PREAD_PWRITE < 1 + int saved_errno; + off_t verified; + off_t off_orig; + off_t off_last; +#endif + + if (io_args(fd, mem, nrw, off, rw_type) + == -1) { + return -1; + } + + r = -1; + + /* do not use loop_eagain on + * normal files + */ + + if (!loop_eagain) { + /* check whether the file + * changed + */ + + if (check_file(fd, &st) == -1) + return -1; + } + + if (rw_type >= IO_PREAD) + positional_rw = 1; /* pread/pwrite */ + else + positional_rw = 0; /* read/write */ + +try_rw_again: + + if (!positional_rw) { +#if defined(HAVE_REAL_PREAD_PWRITE) && \ + HAVE_REAL_PREAD_PWRITE > 0 +real_pread_pwrite: +#endif + if (rw_type == IO_WRITE) + r = write(fd, mem, nrw); + else if (rw_type == IO_READ) + r = read(fd, mem, nrw); +#if defined(HAVE_REAL_PREAD_PWRITE) && \ + HAVE_REAL_PREAD_PWRITE > 0 + else if (rw_type == IO_PWRITE) + r = pwrite(fd, mem, nrw, off); + else if (rw_type == IO_PREAD) + r = pread(fd, mem, nrw, off); +#endif + + if (r == -1 && (errno == try_err(loop_eintr, EINTR) + || errno == try_err(loop_eagain, EAGAIN))) + goto try_rw_again; + + return rw_over_nrw(r, nrw); + } + +#if defined(HAVE_REAL_PREAD_PWRITE) && \ + HAVE_REAL_PREAD_PWRITE > 0 + goto real_pread_pwrite; +#else + if ((off_orig = lseek_on_eintr(fd, (off_t)0, SEEK_CUR, + loop_eagain, loop_eintr)) == (off_t)-1) { + r = -1; + } else if (lseek_on_eintr(fd, off, SEEK_SET, + loop_eagain, loop_eintr) == (off_t)-1) { + r = -1; + } else { + verified = lseek_on_eintr(fd, (off_t)0, SEEK_CUR, + loop_eagain, loop_eintr); + + /* abort if the offset changed, + * indicating race condition. if + * off_reset enabled, reset *ONCE* + */ + + if (off_reset && off != verified) + lseek_on_eintr(fd, off, SEEK_SET, + loop_eagain, loop_eintr); + + do { + /* check offset again, repeatedly. + * even if off_reset is set, this + * aborts if offsets change again + */ + + verified = lseek_on_eintr(fd, (off_t)0, SEEK_CUR, + loop_eagain, loop_eintr); + + if (off != verified) + goto err_prw; + + if (rw_type == IO_PREAD) + r = read(fd, mem, nrw); + else if (rw_type == IO_PWRITE) + r = write(fd, mem, nrw); + + if (rw_over_nrw(r, nrw) == -1) { + errno = EIO; + break; + } + + } while (r == -1 && + (errno == try_err(loop_eintr, EINTR) || + errno == try_err(loop_eagain, EAGAIN))); + } + + saved_errno = errno; + + off_last = lseek_on_eintr(fd, off_orig, SEEK_SET, + loop_eagain, loop_eintr); + + if (off_last != off_orig) { + errno = saved_errno; + goto err_prw; + } + + errno = saved_errno; + + return rw_over_nrw(r, nrw); +#endif + +err_prw: + errno = EIO; + return -1; +} + +int +io_args(int fd, void *mem, unsigned long nrw, + off_t off, int rw_type) +{ + /* obviously */ + if (mem == NULL) + goto err_io_args; + + /* uninitialised fd */ + if (fd < 0) + goto err_io_args; + + /* negative offset */ + if (off < 0) + goto err_io_args; + + /* prevent zero-byte rw */ + if (!nrw) + goto err_io_args; + + /* prevent overflow */ + if (nrw > (unsigned long)X_LONG_MAX) + goto err_io_args; + + /* prevent overflow */ + if (((unsigned long)off + nrw) < (unsigned long)off) + goto err_io_args; + + if (rw_type > IO_PWRITE) + goto err_io_args; + + return 0; + +err_io_args: + errno = EIO; + return -1; +} + +int +check_file(int fd, struct stat *st) +{ + if (fstat(fd, st) == -1) + goto err_is_file; + + if (!S_ISREG(st->st_mode)) + goto err_is_file; + + return 0; + +err_is_file: + errno = EIO; + return -1; +} + +/* POSIX can say whatever it wants. + * specification != implementation + */ + +long +rw_over_nrw(long r, unsigned long nrw) +{ + /* not a libc bug, but we + * don't like the number zero + */ + if (!nrw) + goto err_rw_over_nrw; + + if (r == -1) + return r; + + if ((unsigned long) + r > X_LONG_MAX) { + + /* Theoretical buggy libc + * check. Extremely academic. + * + * Specifications never + * allow this return value + * to exceed SSIZE_T, but + * spec != implementation + * + * Check this after using + * [p]read() or [p]write() + * + * NOTE: here, we assume + * long integers are the + * same size as SSIZE_T + */ + + goto err_rw_over_nrw; + } + + /* Theoretical buggy libc: + * Should never return a number of + * bytes above the requested length. + */ + if ((unsigned long)r > nrw) + goto err_rw_over_nrw; + + return r; + +err_rw_over_nrw: + + errno = EIO; + return -1; +} + +#if !defined(HAVE_REAL_PREAD_PWRITE) || \ + HAVE_REAL_PREAD_PWRITE < 1 +off_t +lseek_on_eintr(int fd, off_t off, int whence, + int loop_eagain, int loop_eintr) +{ + off_t old; + + old = -1; + + do { + old = lseek(fd, off, whence); + } while (old == (off_t)-1 && ( + errno == try_err(loop_eintr, EINTR) || + errno == try_err(loop_eagain, EAGAIN))); + + return old; +} +#endif + +int +try_err(int loop_err, int errval) +{ + if (loop_err) + return errval; + + return -1; +} + +int +close_on_eintr(int fd) +{ + int r; + int saved_errno = errno; + + do { + r = close(fd); + } while (r == -1 && errno == EINTR); + + if (r > -1) + errno = saved_errno; + + return r; +} + +int +fsync_on_eintr(int fd) +{ + int r; + + do { + r = fsync(fd); + } while (r == -1 && errno == EINTR); + + return r; +} |