[Cluster-devel] [PATCH 4/6] mkfs.gfs2: Use libblkid for checking contents

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

Looks good. Do we need to change the package spec file now we no longer
need file?

Steve.

On Tue, 2013-05-14 at 11:45 +0100, Andrew Price wrote:
> Use libblkid to probe the contents of the target device instead of
> execing 'file'.
> 
> Signed-off-by: Andrew Price <anprice@redhat.com>
> ---
>  gfs2/mkfs/main_mkfs.c | 181 ++++++++++++++------------------------------------
>  1 file changed, 51 insertions(+), 130 deletions(-)
> 
> diff --git a/gfs2/mkfs/main_mkfs.c b/gfs2/mkfs/main_mkfs.c
> index 9949a46..91c89d3 100644
> --- a/gfs2/mkfs/main_mkfs.c
> +++ b/gfs2/mkfs/main_mkfs.c
> @@ -20,6 +20,7 @@
>  #include <libintl.h>
>  #include <sys/ioctl.h>
>  #include <limits.h>
> +#include <blkid.h>
>  
>  #define _(String) gettext(String)
>  
> @@ -123,6 +124,7 @@ static void opts_init(struct mkfs_opts *opts)
>  	opts->rgsize = GFS2_DEFAULT_RGSIZE;
>  	opts->lockproto = "lock_dlm";
>  	opts->locktable = "";
> +	opts->confirm = 1;
>  }
>  
>  #ifndef BLKDISCARD
> @@ -475,105 +477,6 @@ static void opts_check(struct mkfs_opts *opts)
>  
>  }
>  
> -static int get_file_output(int fd, char *buffer, size_t buflen)
> -{
> -	struct pollfd pf = { .fd = fd, .events = POLLIN|POLLRDHUP };
> -	int flags;
> -	int pos = 0;
> -	int rv;
> -
> -	flags = fcntl(fd, F_GETFL, 0);
> -	if (flags < 0)
> -		return flags;
> -
> -	flags |= O_NONBLOCK;
> -	rv = fcntl(fd, F_SETFL, flags);
> -	if (rv < 0)
> -		return rv;
> -
> -	while (1) {
> -		rv = poll(&pf, 1, 10 * 1000);
> -		if (rv == 0)
> -			break;
> -		if (rv < 0)
> -			return rv;
> -		if (pf.revents & POLLIN) {
> -			rv = read(fd, buffer + pos,
> -				   buflen - pos);
> -			if (rv < 0) {
> -				if (errno == EAGAIN)
> -					continue;
> -				return rv;
> -			}
> -			if (rv == 0)
> -				break;
> -			pos += rv;
> -			if (pos >= buflen)
> -				return -1;
> -			buffer[pos] = 0;
> -			continue;
> -		}
> -		if (pf.revents & (POLLRDHUP | POLLHUP | POLLERR))
> -			break;
> -	}
> -	return 0;
> -}
> -
> -static void check_dev_content(const char *devname)
> -{
> -	struct sigaction sa;
> -	char content[1024] = { 0, };
> -	char * args[] = {
> -		(char *)"/usr/bin/file",
> -		(char *)"-bsL",
> -		(char *)devname,
> -		NULL };
> -	int p[2] = {-1, -1};
> -	int ret;
> -	int pid;
> -
> -	ret = sigaction(SIGCHLD, NULL, &sa);
> -	if  (ret)
> -		return;
> -	sa.sa_handler = SIG_IGN;
> -	sa.sa_flags |= (SA_NOCLDSTOP | SA_NOCLDWAIT);
> -	ret = sigaction(SIGCHLD, &sa, NULL);
> -	if (ret)
> -		goto fail;
> -
> -	ret = pipe(p);
> -	if (ret)
> -		goto fail;
> -
> -	pid = fork();
> -
> -	if (pid < 0) {
> -		close(p[1]);
> -		goto fail;
> -	}
> -
> -	if (pid) {
> -		close(p[1]);
> -		ret = get_file_output(p[0], content, sizeof(content));
> -		if (ret) {
> -fail:
> -			printf( _("Content of file or device unknown (do you have GNU fileutils installed?)\n"));
> -		} else {
> -			if (*content == 0)
> -				goto fail;
> -			printf( _("It appears to contain: %s"), content);
> -		}
> -		if (p[0] >= 0)
> -			close(p[0]);
> -		return;
> -	}
> -
> -	close(p[0]);
> -	dup2(p[1], STDOUT_FILENO);
> -	close(STDIN_FILENO);
> -	exit(execv(args[0], args));
> -}
> -
>  static void print_results(struct gfs2_sbd *sdp, uint64_t real_device_size,
>                            struct mkfs_opts *opts, unsigned char uuid[16])
>  {
> @@ -594,30 +497,27 @@ static void print_results(struct gfs2_sbd *sdp, uint64_t real_device_size,
>  	printf("%-27s%s\n", _("UUID:"), str_uuid(uuid));
>  }
>  
> -/**
> - * If path is a symlink, return 1 with *abspath pointing to the absolute path,
> - * otherwise return 0. Exit on errors. The caller must free the memory pointed
> - * to by *abspath.
> - */
> -static int is_symlink(const char *path, char **abspath)
> +static void warn_of_destruction(const char *path)
>  {
>  	struct stat lnkstat;
> +	char *abspath = NULL;
>  
>  	if (lstat(path, &lnkstat) == -1) {
>  		perror(_("Failed to lstat the device"));
>  		exit(EXIT_FAILURE);
>  	}
> -	if (!S_ISLNK(lnkstat.st_mode)) {
> -		return 0;
> -	}
> -	*abspath = canonicalize_file_name(path);
> -	if (*abspath == NULL) {
> -		perror(_("Could not find the absolute path of the device"));
> -		exit(EXIT_FAILURE);
> +	if (S_ISLNK(lnkstat.st_mode)) {
> +		abspath = canonicalize_file_name(path);
> +		if (abspath == NULL) {
> +			perror(_("Could not find the absolute path of the device"));
> +			exit(EXIT_FAILURE);
> +		}
> +		/* Translators: Example: "/dev/vg/lv is a symbolic link to /dev/dm-2" */
> +		printf( _("%s is a symbolic link to %s\n"), path, abspath);
> +		path = abspath;
>  	}
> -	/* Translators: Example: "/dev/vg/lv is a symbolic link to /dev/dm-2" */
> -	printf( _("%s is a symbolic link to %s\n"), path, *abspath);
> -	return 1;
> +	printf(_("This will destroy any data on %s\n"), path);
> +	free(abspath);
>  }
>  
>  static int writerg(int fd, const struct rgrp_tree *rgt, const unsigned bsize)
> @@ -751,6 +651,38 @@ static void sbd_init(struct gfs2_sbd *sdp, struct mkfs_opts *opts, struct lgfs2_
>  	}
>  }
>  
> +static int probe_contents(int fd)
> +{
> +	int ret;
> +	const char *contents;
> +	blkid_probe pr = blkid_new_probe();
> +	if (pr == NULL || blkid_probe_set_device(pr, fd, 0, 0) != 0
> +	               || blkid_probe_enable_superblocks(pr, TRUE) != 0
> +	               || blkid_probe_enable_partitions(pr, TRUE) != 0) {
> +		fprintf(stderr, _("Failed to create probe\n"));
> +		return -1;
> +	}
> +
> +	ret = blkid_do_fullprobe(pr);
> +	if (ret == -1) {
> +		fprintf(stderr, _("Failed to probe device\n"));
> +		return -1;
> +	}
> +
> +	if (ret == 1)
> +		return 0;
> +
> +	if (!blkid_probe_lookup_value(pr, "TYPE", &contents, NULL)) {
> +		printf(_("It appears to contain an existing filesystem (%s)\n"), contents);
> +	} else if (!blkid_probe_lookup_value(pr, "PTTYPE", &contents, NULL)) {
> +		printf(_("It appears to contain a partition table (%s).\n"), contents);
> +	}
> +
> +	blkid_free_probe(pr);
> +
> +	return 0;
> +}
> +
>  void main_mkfs(int argc, char *argv[])
>  {
>  	struct gfs2_sbd sbd;
> @@ -758,9 +690,6 @@ void main_mkfs(int argc, char *argv[])
>  	struct lgfs2_dev_info dinfo;
>  	int error;
>  	unsigned char uuid[16];
> -	char *absname = NULL;
> -	char *fdpath = NULL;
> -	int islnk = 0;
>  	int fd;
>  
>  	opts_init(&opts);
> @@ -783,21 +712,13 @@ void main_mkfs(int argc, char *argv[])
>  	}
>  
>  	opts_check(&opts);
> -	sbd_init(&sbd, &opts, &dinfo, fd);
> +	warn_of_destruction(opts.device);
>  
> -	if (asprintf(&fdpath, "/proc/%d/fd/%d", getpid(), fd) < 0) {
> -		perror(_("Failed to build string"));
> +	error = probe_contents(fd);
> +	if (error)
>  		exit(EXIT_FAILURE);
> -	}
>  
> -	if (!opts.override) {
> -		islnk = is_symlink(opts.device, &absname);
> -		printf(_("This will destroy any data on %s.\n"), islnk ? absname : opts.device);
> -		free(absname);
> -		check_dev_content(fdpath);
> -		opts.confirm = 1;
> -	}
> -	free(fdpath);
> +	sbd_init(&sbd, &opts, &dinfo, fd);
>  
>  	if (opts.confirm && !opts.override)
>  		are_you_sure();