On 4/26/14, 7:00 PM, Theodore Ts'o wrote:
> This is useful when creating a filesystem for use with a VM, for
> example.
Ok, backing up to here from the "print if we're creating a file" thread.
Considering the questions about typos in /dev/$FOO etc, why is it desirable
to create the file within mke2fs? If you're making it for a VM, wouldn't
you want to control the creation (i.e. fallocated vs. sparse, for example,
as well as permissions) and not just have things magically happen?
fallocate -l 8g myfile; mkfs.ext4 myfile
or
truncate -s 8589934592 myfile; mkfs.ext4 myfile
doesn't seem all that onerous.
-Eric
> Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
> ---
> misc/mke2fs.c | 3 ++-
> misc/util.c | 20 ++++++++++++++++----
> misc/util.h | 1 +
> 3 files changed, 19 insertions(+), 5 deletions(-)
>
> diff --git a/misc/mke2fs.c b/misc/mke2fs.c
> index fa61e7b..a2b1f65 100644
> --- a/misc/mke2fs.c
> +++ b/misc/mke2fs.c
> @@ -1749,7 +1749,8 @@ profile_error:
> if (optind < argc)
> usage();
>
> - if (!check_plausibility(device_name, 0, &is_device) && !force)
> + if (!check_plausibility(device_name, CREATE_FILE,
> + &is_device) && !force)
> proceed_question();
>
> check_mount(device_name, force, _("filesystem"));
> diff --git a/misc/util.c b/misc/util.c
> index 08ec761..f85942e 100644
> --- a/misc/util.c
> +++ b/misc/util.c
> @@ -13,6 +13,7 @@
> #define _LARGEFILE64_SOURCE
>
> #include "config.h"
> +#include <fcntl.h>
> #include <stdio.h>
> #include <string.h>
> #ifdef HAVE_ERRNO_H
> @@ -21,6 +22,7 @@
> #ifdef HAVE_LINUX_MAJOR_H
> #include <linux/major.h>
> #endif
> +#include <sys/types.h>
> #ifdef HAVE_SYS_STAT_H
> #include <sys/stat.h>
> #endif
> @@ -85,19 +87,29 @@ void proceed_question(void)
> */
> int check_plausibility(const char *device, int flags, int *ret_is_dev)
> {
> - int val, is_dev = 0;
> + int fd, is_dev = 0;
> ext2fs_struct_stat s;
> + int fl = O_RDONLY;
>
> - val = ext2fs_stat(device, &s);
> + if (flags & CREATE_FILE)
> + fl |= O_CREAT;
>
> - if(val == -1) {
> - fprintf(stderr, _("Could not stat %s --- %s\n"),
> + fd = open(device, fl, 0666);
> + if (fd < 0) {
> + fprintf(stderr, _("Could not open %s: %s\n"),
> device, error_message(errno));
> if (errno == ENOENT)
> fputs(_("\nThe device apparently does not exist; "
> "did you specify it correctly?\n"), stderr);
> exit(1);
> }
> +
> + if (ext2fs_fstat(fd, &s) < 0) {
> + perror("stat");
> + exit(1);
> + }
> + close(fd);
> +
> if (S_ISBLK(s.st_mode))
> is_dev = 1;
> #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
> diff --git a/misc/util.h b/misc/util.h
> index 867f4b0..b80d489 100644
> --- a/misc/util.h
> +++ b/misc/util.h
> @@ -19,6 +19,7 @@ extern char *journal_location_string;
> * Flags for check_plausibility()
> */
> #define CHECK_BLOCK_DEV 0x0001
> +#define CREATE_FILE 0x0002
>
> #ifndef HAVE_STRCASECMP
> extern int strcasecmp (char *s1, char *s2);
>
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