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

[Andrew Price <anprice@redhat.com>]

On 14/05/13 11:52, Steven Whitehouse wrote:
> Hi,
>
> Looks good. Do we need to change the package spec file now we no longer
> need file?

Yes, I've made a note to do that when we do the next release along with 
updating the build docs.

Andy

>
> 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();
>
>