diff options
Diffstat (limited to 'contrib/syslinux-4.02/libinstaller/advio.c')
| -rw-r--r-- | contrib/syslinux-4.02/libinstaller/advio.c | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/libinstaller/advio.c b/contrib/syslinux-4.02/libinstaller/advio.c new file mode 100644 index 0000000..56f607d --- /dev/null +++ b/contrib/syslinux-4.02/libinstaller/advio.c @@ -0,0 +1,162 @@ +/* ----------------------------------------------------------------------- * + * + * Copyright 2007-2008 H. Peter Anvin - All Rights Reserved + * Copyright 2010 Intel Corporation; author: H. Peter Anvin + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, Inc., 53 Temple Place Ste 330, + * Boston MA 02111-1307, USA; either version 2 of the License, or + * (at your option) any later version; incorporated herein by reference. + * + * ----------------------------------------------------------------------- */ + +/* + * advio.c + * + * Linux ADV I/O + * + * Return 0 on success, -1 on error, and set errno. + * + */ +#define _GNU_SOURCE + +#include <stdio.h> +#include <stdlib.h> +#include <stddef.h> +#include <stdint.h> +#include <string.h> +#include <unistd.h> +#include <errno.h> +#include <fcntl.h> +#include <sys/stat.h> +#include <sys/types.h> +#include "syslxint.h" +#include "syslxcom.h" + +/* + * Read the ADV from an existing instance, or initialize if invalid. + * Returns -1 on fatal errors, 0 if ADV is okay, 1 if the ADV is + * invalid, and 2 if the file does not exist. + */ +int read_adv(const char *path, const char *cfg) +{ + char *file; + int fd = -1; + struct stat st; + int err = 0; + int rv; + + rv = asprintf(&file, "%s%s%s", path, + path[0] && path[strlen(path) - 1] == '/' ? "" : "/", cfg); + + if (rv < 0 || !file) { + perror(program); + return -1; + } + + fd = open(file, O_RDONLY); + if (fd < 0) { + if (errno != ENOENT) { + err = -1; + } else { + syslinux_reset_adv(syslinux_adv); + err = 2; /* Nonexistence is not a fatal error */ + } + } else if (fstat(fd, &st)) { + err = -1; + } else if (st.st_size < 2 * ADV_SIZE) { + /* Too small to be useful */ + syslinux_reset_adv(syslinux_adv); + err = 0; /* Nothing to read... */ + } else if (xpread(fd, syslinux_adv, 2 * ADV_SIZE, + st.st_size - 2 * ADV_SIZE) != 2 * ADV_SIZE) { + err = -1; + } else { + /* We got it... maybe? */ + err = syslinux_validate_adv(syslinux_adv) ? 1 : 0; + } + + if (err < 0) + perror(file); + + if (fd >= 0) + close(fd); + + free(file); + + return err; +} + +/* + * Update the ADV in an existing installation. + */ +int write_adv(const char *path, const char *cfg) +{ + unsigned char advtmp[2 * ADV_SIZE]; + char *file; + int fd = -1; + struct stat st, xst; + int err = 0; + int rv; + + rv = asprintf(&file, "%s%s%s", path, + path[0] && path[strlen(path) - 1] == '/' ? "" : "/", cfg); + + if (rv < 0 || !file) { + perror(program); + return -1; + } + + fd = open(file, O_RDONLY); + if (fd < 0) { + err = -1; + } else if (fstat(fd, &st)) { + err = -1; + } else if (st.st_size < 2 * ADV_SIZE) { + /* Too small to be useful */ + err = -2; + } else if (xpread(fd, advtmp, 2 * ADV_SIZE, + st.st_size - 2 * ADV_SIZE) != 2 * ADV_SIZE) { + err = -1; + } else { + /* We got it... maybe? */ + err = syslinux_validate_adv(advtmp) ? -2 : 0; + if (!err) { + /* Got a good one, write our own ADV here */ + clear_attributes(fd); + + /* Need to re-open read-write */ + close(fd); + fd = open(file, O_RDWR | O_SYNC); + if (fd < 0) { + err = -1; + } else if (fstat(fd, &xst) || xst.st_ino != st.st_ino || + xst.st_dev != st.st_dev || xst.st_size != st.st_size) { + fprintf(stderr, "%s: race condition on write\n", file); + err = -2; + } + /* Write our own version ... */ + if (xpwrite(fd, syslinux_adv, 2 * ADV_SIZE, + st.st_size - 2 * ADV_SIZE) != 2 * ADV_SIZE) { + err = -1; + } + + sync(); + set_attributes(fd); + } + } + + if (err == -2) + fprintf(stderr, "%s: cannot write auxilliary data (need --update)?\n", + file); + else if (err == -1) + perror(file); + + if (fd >= 0) + close(fd); + if (file) + free(file); + + return err; +} |